Spore immobilization and its analytical performance for monitoring of aflatoxin M1 in milk.

Immobilization of Bacillus megaterium spores on Eppendorf tubes through physical adsorption has been used in the detection of aflatoxin M1 (AFM1) in milk within real time of 45 ± 5 min using visual observation of changes in a chromogenic substrate. The appearance of a sky-blue colour indicates the absence of AFM1 in milk, whereas no colour change indicates the presence of AFM1 in milk at a 0.5 ppb Codex maximum residue limit. The working performance of the immobilized spores was shown to persist for up to 6 months. Further, spores immobilized on 96-well black microtitre plates by physical adsorption and by entrapment on sensor disk showed a reduction in detection sensitivity to 0.25 ppb within a time period of 20 ± 5 min by measuring fluorescence using a microbiological plate reader through the addition of milk and fluorogenic substrate. A high fluorescence ratio indicated more substrate hydrolysis due to spore-germination-mediated release of marker enzymes of spores in the absence of AFM1 in milk; however, low fluorescence ratios indicated the presence of AFM1 at 0.25 ppb. Immobilized spores on 96-well microtitre plates and sensor disks have shown better reproducibility after storage at 4 °C for 6 months. Chromogenic assay showed 1.38% false-negative and 2.77% false-positive results while fluorogenic assay showed 4.16% false-positive and 2.77% false-negative results when analysed for AFM1 using 72 milk samples containing raw, pasteurized, and dried milk. Immobilization of spores makes these chromogenic and fluorogenic assays portable, selective, cost-effective for real-time detection of AFM1 in milk at the dairy farm, reception dock, and manufacturing units of the dairy industry.

Estimation of lean body weight in older women with hip fracture.

OBJECTIVE: Lean body weight (LBW) decreases with age while total body fat increases, resulting in altered drug pharmacokinetics. A semi-mechanistic equation estimating LBW using height, weight and sex has been developed for potential use across a wide range of body compositions. The aim of this study was to determine the ability of the LBW equation to estimate dual energy x-ray absorptiometry-derived fat free mass (FFM(DXA)) in a population of older women with recent hip fracture. METHODS: Baseline, four and 12 month data obtained from 23 women enrolled in the Sarcopenia and Hip Fracture study were pooled to give 58 measurements. LBW was estimated using the equation: LBW (kg) = (9270 x Wt) / (8780 + (244 x BMI)). Body composition was classified as: 'normal' (BMI <25kg/m(2) and not sarcopenic), 'overweight-obese' (BMI >25kg/m(2) and not sarcopenic), 'sarcopenic' (sarcopenic and BMI <25kg/m(2)), or 'sarcopenic-obese' (sarcopenic and BMI >25kg/m(2)). The ability of the LBW equation to predict FFMDXA was determined graphically using Bland-Altman plots and quantitatively using the method of Sheiner and Beal. RESULTS: The mean ± SD age of female participants women was 83±7 years (n=23). Sarcopenia was frequently observed (65.2%). Bland-Altman plots demonstrated an underestimation by the LBW equation compared to FFMDXA. The bias (95% CI) and precision (95% CI) calculated using the method of Sheiner and Beal was 0.5kg (-0.7, 1.66kg) and 4.4kg (-3.7, 12.4kg) respectively for pooled data. CONCLUSION: This equation can be used to easily calculate LBW. When compared to FFMDXA, the LBW equation resulted in a small underestimation on average in this population of women with recent hip fracture. The degree of bias may not be clinically important although further studies of larger heterogeneous cohorts are needed to investigate and potentially improve the accuracy of this predictive equation in larger clinical cohorts.

The efficacy of exercise as a long-term antidepressant in elderly subjects: a randomized, controlled trial.

BACKGROUND: Pharmacological treatment of depression in geriatric patients is often difficult. Although unsupervised exercise has been shown to benefit younger depressed patients, there is no evidence that unsupervised exercise can be used as a maintenance treatment for depression in elderly patients. Our aim was to test the feasibility and efficacy of unsupervised exercise as a long-term treatment for clinical depression in elderly patients. METHODS: We studied 32 subjects (71.3 +/- 1.2 years of age, mean +/- SE) in a 20-week, randomized, controlled trial, with follow-up at 26 months. Subjects were community-dwelling patients with major or minor depression or dysthymia. Exercisers engaged in 10 weeks of supervised weight-lifting exercise followed by 10 weeks of unsupervised exercise. Controls attended lectures for 10 weeks. No contact was made with either group after 20 weeks until final follow-up. Blinded assessment was made with the Beck Depression Inventory (BDI), the Philadelphia Geriatric Morale Scale, and Ewart's Self Efficacy Scale at 20 weeks and with the BDI and physical activity questionnaire at 26 months. RESULTS: Patients randomized to the exercise condition completed 18 +/- 2 sessions of unsupervised exercise during Weeks 10 to 20. The BDI was significantly reduced at both 20 weeks and 26 months of follow-up in exercisers compared with controls (p <.05-.001). At the 26-month follow-up, 33% of the exercisers were still regularly weight lifting, versus 0% of controls (p <.05). CONCLUSIONS: Unsupervised weight-lifting exercise maintains its antidepressant effectiveness at 20 weeks in depressed elderly patients. Long-term changes in exercise behavior are possible in some patients even without supervision.

A novel potassium channel gene, KCNQ2, is mutated in an inherited epilepsy of newborns.

Idiopathic generalized epilepsies account for about 40% of epilepsy up to age 40 and commonly have a genetic basis. One type is benign familial neonatal convulsions (BFNC), a dominantly inherited disorder of newborns. We have identified a sub-microscopic deletion of chromosome 20q13.3 that co-segregates with seizures in a BFNC family. Characterization of cDNAs spanning the deleted region identified one encoding a novel voltage-gated potassium channel, KCNQ2, which belongs to a new KQT-like class of potassium channels. Five other BFNC probands were shown to have KCNQ2 mutations, including two transmembrane missense mutations, two frameshifts and one splice-site mutation. This finding in BFNC provides additional evidence that defects in potassium channels are involved in the mammalian epilepsy phenotype.

A pore mutation in a novel KQT-like potassium channel gene in an idiopathic epilepsy family.

Epileptic disorders affect about 20-40 million people worldwide, and 40% of these are idiopathic generalized epilepsies (IGEs; ref. 1). Most of the IGEs that are inherited are complex, multigenic diseases. To address basic mechanisms for epilepsies, we have focused on one well-defined class of IGEs with an autosomal-dominant mode of inheritance: the benign familial neonatal convulsions (BFNC; refs 2,3). Genetic heterogeneity of BFNC has been observed. Two loci, EBN1 and EBN2, have been mapped by linkage analysis to chromosome 20q13 (refs 5,6) and chromosome 8q24 (refs 7,8), respectively. By positional cloning, we recently identified the gene for EBN1 as KCNQ2 (ref. 9). This gene, a voltage-gated potassium channel, based on homology, is a member of the KQT-like family. Here we describe an additional member, KCNQ3. We mapped this new gene to chromosome 8, between markers D8S256 and D8S284 on a radiation hybrid map. We screened KCNQ3 for mutations in the large BFNC family previously linked to chromosome 8q24 in the same marker interval. We found a missense mutation in the critical pore region in perfect co-segregation with the BFNC phenotype. The same conserved amino acid is also mutated in KVLQT1 (KCNQ1) in an LQT patient. KCNQ2, KCNQ3 and undiscovered genes of the same family of K+ channels are strong candidates for other IGEs.

A randomized controlled trial of the effect of exercise on sleep.

We tested the hypothesis that exercise would improve subjective sleep quality and activity in depressed elders. A 10-week randomized controlled trial was utilized. Participants consisted of a volunteer sample, aged > 60 with a diagnosis of major or minor depression or dysthymia. A total of 32 subjects aged 60-84 years with a mean age of 71.3 +/- 1.2 years was used. Intervention consisted of a supervised weight-training program three times a week or an attention-control group. Main outcome measures were Pittsburgh Subjective Sleep Quality Index (PSQI), Likert Scale of Subjective Sleep Quality and Quantity. Paffenbarger Activity Index. Geriatric Depression Scale (GDS). Beck Depression Inventory (BDI), Hamilton Rating Scale of Depression (HRSD), and the Medical Outcomes Survey Short Form 36 (SF-36). Results showed that exercise significantly improved all subjective sleep-quality and depression measures. Depression measures were reduced by approximately twice that of controls. Habitual activity was not significantly increased by exercise. Quality of life subscales significantly improved. In a forward stepwise multiple regression, percent improvement in GDS and percent increase in strength remained significant predictors of the improvement in total PSQI score (r = 0.71, p = 0.0002). In conclusion, weight lifting exercise was effective in improving subjective sleep quality, depression, strength, and quality of life without significantly changing habitual activity.

A randomized controlled trial of progressive resistance training in depressed elders.

BACKGROUND: Depression in elderly people may be contributed to by the multiple losses of aging. Exercise has the potential to positively impact many of these losses simultaneously. We tested the hypothesis that progressive resistance training (PRT) would reduce depression while improving physiologic capacity, quality of life, morale, function and self-efficacy without adverse events in an older, significantly depressed population. METHODS: We conducted a 10-week randomized controlled trial of volunteers aged 60 and above with major or minor depression or dysthymia. Subjects were randomized for 10 weeks to either a supervised PRT program three times a week or an attention-control group. RESULTS: A total of 32 subjects aged 60-84, mean age 71.3 +/- 1.2 yr, were randomized and completed the study. No significant adverse events occurred. Median compliance was 95%. PRT significantly reduced all depression measures (Beck Depression Inventory in exercisers 21.3 +/- 1.8 to 9.8 +/- 2.4 versus controls 18.4 +/- 1.7 to 13.8 +/- 2, p = .002; Hamilton Rating Scale of Depression in exercisers 12.3 +/- 0.9 to 5.3 +/- 1.3 versus controls 11.4 +/- 1.0 to 8.9 +/- 1.3, p = .008). Quality of life subscales of bodily pain (p = .001), vitality (p = .002), social functioning (p = .008), and role emotional (p = .02) were all significantly improved by exercise compared to controls. Strength increased a mean of 33% +/- 4% in exercisers and decreased 2% +/- 2% in controls (p < .0001). In a multiple stepwise regression model, intensity of training was a significant independent predictor of decrease in depression scores (r2 = .617, p = .0002). CONCLUSIONS: PRT is an effective antidepressant in depressed elders, while also improving strength, morale, and quality of life.

Dynamic dopaminergic regulation of neuropeptide Y systems in discrete striatal and accumbens regions.

In this study we evaluated the effects of multiple administrations of selective dopamine D1 and D2 receptor agonists and antagonists on striatal, nigral, accumbens, pallidal and cortical neuropeptide Y systems. Treatment with the D1 receptor agonist, SKF 38393, decreased, while that with the D1 receptor antagonist, SCH 23390, increased neuropeptide Y-like immunoreactivity in the globus pallidus and several regions within the caudate-putamen. SCH 23390 did not change accumbens neuropeptide Y-like immunoreactivity levels but SKF 38393 increased neuropeptide Y-like immunoreactivity levels in anterior and decreased neuropeptide Y-like immunoreactivity levels in the posterior nucleus accumbens. Interestingly, reductions in neuropeptide Y-like immunoreactivity content occurred in response to administrations of both D2 receptor agonist, quinpirole, or antagonist, sulpiride, in all identified regions of each structure at some time point. These data suggest that the neuropeptide Y systems studied may be regulated by selective activity at postsynaptic or presynaptic dopamine receptors. They further suggest that within structures such as the caudate-putamen and nucleus accumbens are multiple distinct neuropeptide Y systems which are uniquely influenced by dopamine receptors.

Role of N-methyl-D-aspartate receptors in dopamine D1-, but not D2-, mediated changes in striatal and accumbens neurotensin systems.

The role of N-methyl-D-aspartate (NMDA) receptors in specific D1 and D2 regulation of striatal and accumbens neurotensin (NT) systems was investigated. As demonstrated previously, stimulation of D1 receptors with multiple administrations of SKF 38393 significantly increased striatal and accumbens NT content to approximately 145% of control. These responses were completely blocked by coadministration of the non-competitive NMDA antagonist, MK 801. Previous studies have documented that D2 receptors tonically regulate striatal NT systems. Thus, multiple doses of sulpiride, a D2 antagonist, increased striatal NT content to 167% of control while quinpirole, a D2 agonist, decreased striatal NT content to 58% of control. MK 801 did not alter either striatal NT response to D2 manipulation. As previously reported, levels of accumbens NT changed only in response to D2 blockade and not to D2 stimulation. Thus, sulpiride increased accumbens NT content to 138% of control; this was not blocked by the coadministration of MK 801. NT content also significantly increased after stimulation of glutamate receptors with NMDA. To determine if D1 receptors participate in this NMDA-mediated change, the D1 antagonist SCH 23390 was coadministered. Blockade of D1 receptors did not significantly alter the response of striatal NT systems to NMDA. However, in both striatum and nucleus accumbens, the NMDA effect on NT systems appeared to be lessened. In summary, expression of D1-, but not D2-mediated changes in striatal and accumbens NT systems are markedly dependent on NMDA receptor activity. In comparison, expression of the NMDA-mediated changes in the same NT systems do not appear to be as dependent on D1 receptor activity.

N-Methyl-D-aspartate receptors mediate dopamine-induced changes in extrapyramidal and limbic dynorphin systems.

The N-methyl-D-aspartate (NMDA)-type glutamate receptor was shown to mediate dopamine-induced dynorphin A (Dyn) changes in extrapyramidal and limbic structures. MK801, a potent noncompetitive antagonist of the NMDA receptor, blocked increases in striatal and nigral Dyn content following single and multiple administrations of methamphetamine (METH). Significant attenuation of the METH-induced increases occurred with MK801 doses of 0.1 mg/kg/dose with complete blockade at 2.5 mg/kg/dose. Similar to METH, NMDA itself caused significant increases in striatal and nigral Dyn content. The NMDA-induced increase in striatal Dyn content was blocked by coadministration of an intermediate dose of MK801. The Dyn system associated with the nucleus accumbens responded in a similar manner in that MK801 totally blocked the METH-induced increases; moreover, NMDA elevated the Dyn content in this structure. The inability of MK801 to alter the quinpirole-induced decrease in striatal Dyn content suggests that the NMDA receptor is not involved in the D2 receptor regulation of striatal Dyn systems.

Dopamine-mediated changes in central nervous system neurotensin systems: a role for NMDA receptors.

A role for N-methyl-D-aspartate (NMDA)-type glutamate receptors in mediating the dopaminergic regulation of neurotensin (NT) systems was observed in extrapyramidal and limbic structures. Blockade of the NMDA receptor with the non-competitive antagonist, MK801, prevented increases in striatal and nigral levels of NT following both single and multiple administrations of methamphetamine. Significant attenuation of the methamphetamine-induced changes in the striatal NT system were observed with MK801 doses as low as 0.01 mg/kg per dose. In contrast, administration of NMDA caused significant increases in both striatal and nigral NT. The NMDA-induced increase in striatal NT content, like that caused by methamphetamine, was blocked by MK801. The NT system associated with the nucleus accumbens responded in a similar manner in that MK801 (0.1 mg/kg per dose) totally blocked the methamphetamine-induced increases and NMDA administration elevated the NT levels in this structure. Since the methamphetamine-related changes in NT content have been previously shown to be due to increased activity at dopamine D1 receptors, these results strongly suggest that NMDA receptors play an important role in mediating the dopamine D1 regulation of neurotensin systems. Interestingly, the presence of MK801 had no impact on sulpiride-mediated changes in striatal NT levels, suggesting that the NMDA receptor is not linked with the dopamine D2 receptor regulation of NT pathways.