Influence of metabolic stress and metformin on synaptic protein profile in SH-SY5Y-derived neurons

Insulin resistance (IR) is associated with reductions in neuronal proteins often observed with Alzheimer's disease (AD), however, the mechanisms through which IR promotes neurodegeneration/AD pathogenesis are poorly understood. Metformin (MET), a potent activator of the metabolic regulator AMPK is used to treat IR but its effectiveness for AD is unclear. We have previously shown that chronic AMPK activation impairs neurite growth and protein synthesis in SH-SY5Y neurons, however, AMPK activation in IR was not explored. Therefore, we examined the effects of MET-driven AMPK activation with and without IR. Retinoic acid-differentiated SH-SY5Y neurons were treated with: (1) Ctl: 24 h vehicle followed by 24 h Vehicle; (2) HI: 100 nM insulin (24 h HI followed by 24 h HI); or (3) MET: 24 h vehicle followed by 24 h 2 mM metformin; (4) HI/MET: 24 h 100 nM insulin followed by 24 h 100 nM INS+2 mM MET. INS and INS/MET groups saw impairments in markers of insulin signaling (Akt S473, mTOR S2448, p70s6k T389, and IRS-1S636) demonstrating IR was not recovered with MET treatment. All treatment groups showed reductions in neuronal markers (post-synaptic marker HOMER1 mRNA content and synapse marker synaptophysin protein content). INS and MET treatments showed a reduction in the content of the mature neuronal marker NeuN that was prevented by INS/MET. Similarly, increases in cell size/area, neurite length/area observed with INS and MET, were prevented with INS/MET. These findings indicate that IR and MET impair neuronal markers through distinct pathways and suggest that MET is ineffective in treating IR-driven impairments in neurons.

Long-term memory survives nerve injury and the subsequent regeneration process

A three-neuron network (a central pattern generator [CPG]) is both sufficient and necessary to generate aerial respiratory behavior in the pond snail, Lymnaea stagnalis. Aerial respiratory behavior is abolished following a specific nerve crush that results in axotomy to one of the three CPG neurons, RPeD1. Functional regeneration of the crushed neurite occurs within 10 days, allowing aerial respiratory behavior to be restored. Functional regeneration does not occur if the connective is cut rather than crushed. In unaxotomized snails, aerial respiratory behavior can be operantly conditioned, and following memory consolidation, long-term memory (LTM) persists for at least 2 weeks. We used the Lymnaea model system to determine (1) If in naive animals axotomy and the subsequent regeneration result in a nervous system that is competent to mediate associative learning and LTM, and (2) if LTM survives RPeD1 axotomy and the subsequent regenerative process. We show here that (1) A regenerated nervous system is competent to mediate associative memory and LTM, and (2) LTM survives axotomy and the subsequent regenerative process.

An environmentally benign soybean derived fuel as a blending stock or replacement for home heating oil

The use of bio-derived materials both as fuels and/or as blending stocks becomes more attractive as the price of middle distillate fuels, especially home heating oil, continues to rise. Historically, many biomass and agricultural derived materials have been suggested. One of the most difficult problems encountered with home heating oil is that of storage stability. High maintenance costs associated with home heating oil are, in large part, because of this stability problem. In the present research, Soygold, a soybean derived fuel, was added in concentrations of 10%-20% to both a stable middle distillate fuel and an unstable home heating oil. Fuel instability in this article will be further related to the organo-nitrogen compounds present. The soy-fuel mixtures proved stable, and the addition of the soy liquid enhanced both the combustion properties, and dramatically improved the stability of the unstable home heating oil.

The role of exercise in successful ageing

Older people are often expected to accept a passive role in society. Many physical activities have been shown to benefit the mental and physical health of older people. Nurses can help maintain older people's exercise levels by incorporating programmes into nursing care.

Long-term memory of an operantly conditioned respiratory behaviour pattern in lymnaea stagnalis

The freshwater snail Lymnaea stagnalis breaths bimodally either through its skin (cutaneous respiration) or via a rudimentary lung opening called the pneumostome (aerial respiration). Aerial respiratory behaviour can be operantly conditioned. Animals placed in an aquatic, hypoxic environment received a tactile stimulus to the pneumostome area every time they attempted to breathe. Over a period of five training sessions (2.5 days), the animals learned not to breathe, and the number of stimuli received in the fifth session was significantly lower than in the first session. These changes in the respiratory behaviour following the operant paradigm were shown to persist for at least 24 h. We aimed to determine whether the changes in the learned behaviour would persist for longer. We obtained direct evidence that the behavioural changes following operant conditioning persisted for at least 4 weeks following the last training session. However, we found that the persistence of this memory was dependent upon the training procedure used. Memory persisted longer following a spaced training procedure (4 weeks) as opposed to a massed training procedure (2 weeks). Yoked control animals showed no changes in their respiratory behaviour over the same time periods. However, if these yoked control animals were subjected to an operant conditioning procedure, their ability to learn was not impeded. This study demonstrated that operant conditioning of a behaviour pattern in a molluscan preparation can result in long-term memory and that the persistence of the memory is contingent on the training procedure used. <P>

Operant conditioning of aerial respiratory behaviour in Lymnaea stagnalis

In this study, we operantly conditioned the aerial respiratory behaviour of the freshwater snail Lymnaea stagnalis. Aerial respiration in Lymnaea stagnalis is accomplished by the spontaneous opening and closing of its respiratory orifice, the pneumostome, at the water surface. Weak tactile stimulation of the pneumostome area, when the pneumostome is open, evoked only the pneumostome closure response, which is one aspect of the escape-withdrawal reflex. Pneumostome stimulation resulted in its closure and the termination of aerial respiratory activity. A contingent tactile stimulation paradigm was used to operantly condition the animals. Stimulation of the pneumostome whenever the animal attempted to breathe resulted in significantly fewer attempts to open the pneumostome as training progressed. The latency of the first breath (subsequent to stimulation), the number of breaths and the total breathing time were measured before and after each training period. Significant, quantifiable changes in these behavioural parameters were observed only in the operant conditioning group animals. Control animals receiving tactile stimulation to their pneumostome not contingent upon pneumostome opening movements (yoked controls) or those that were physically prevented from surfacing to breathe (hypoxic controls), did not exhibit significant changes in these behavioural parameters. Our data provide the first direct evidence for operant conditioning of respiration in any animal.

Reprographic paper workers: a preliminary study of occupational risk

1. The purpose of this descriptive retrospective study was to identify the prevalence of illness and medical problems among the reprographic paper employees which might be occupationally linked. 2. A telephone survey was developed and 162 workers were interviewed about self reported health problems, occupational history, and demographics. 3. The findings of the study strongly suggest that prevalence of illness and medical problems among particular workers within the plant might be occupationally linked. 4. The most significant implication of this study is its ability to show clearly the pivotal role that occupational health nurses can play in identifying occupationally linked employee health problems through research.

Detection of DNA-adducts in normal and tumorous human prostate biopsies by p-32 postlabeling

Prostate cancer is the most commonly diagnosed cancer in men and the second leading cause of male cancer deaths in the United States. Several risk factors have been identified for prostate cancer, including increased serum testosterone levels, dietary fat intake, and ethnicity. In attempts to detect DNA damage in prostate tissue, we examined in a pilot study 18 pairs (36 samples) of normal and tumorous tissue biopsies from patients ages 50-76 years. DNA was isolated from frozen tissue by solvent extractions with DNA yield ranging from 392-1925 mu g/g tissue (mean 849 +/- 339 mu g/g). Analysis of the DNA by the nuclease P1-mediated P-32-postlabeling assay revealed the presence of multiple adducts in all DNA samples, irrespective of whether the tissue was normal or tumorous. Adduct levels generally ranged from 1-34 (mean 8 +/- 8) per 10(9) nucleotides for normal tissue and 3-37 (mean 11 +/- 9) per 10(9) nucleotides for tumorous tissue. Our data suggest (i) accumulation of DNA adducts in both normal and tumorous tissues; (ii) chromatographic similarity of certain adducts; and (iii) on an average, somewhat higher adduct levels in tumorous than normal tissue. Due to the small sample size examined, it remains to be determined if these DNA adducts were related to any of the risk factors.

Short report: omeprazole plus antibiotic combinations for the eradication of metronidazole-resistant Helicobacter pylori

Twenty-eight Helicobacter pylori-positive patients with metronidazole-resistant isolates and 25 with metronidazole-sensitive isolates were treated for 14 days with 40 mg omeprazole nocte plus 500 mg amoxycillin t.d.s. Eradication of H. pylori, defined as absence of the organism one month after cessation of treatment, was assessed using the [14C]urea breath test. The eradication rate in patients with metronidazole-resistant isolates was 14/28 (50%) while that in patients was metronidazole-sensitive isolates was 12/25 (48%). In contrast to these encouraging eradication rates, very poor results were obtained with a 7-day course of omeprazole (40 mg nocte) in combination with erythromycin ethylsuccinate (500 mg q.d.s.) and tripotassium dicitrato bismuthate tablets (120 mg q.d.s.). The latter eradication rates were 3/20 (15%) in patients taking erythromycin tablets and 3/19 (16%) in those taking a liquid formulation of erythromycin. All treatment regimens were well tolerated and all patients completed the prescribed course of therapy.

Differential effects of general anaesthetics on identified molluscan neurones in situ and in culture

1. The only unifying principle of general anaesthesia is that general anaesthetics interact with membrane components and no single cellular mechanism appears to explain their widespread effects in the central nervous system. 2. The gastropod mollusc, Lymnaea stagnalis, provides an excellent model system for studies on general anaesthetics because it has large, uniquely identifiable nerve cells. Several of these cells are interneurones with identified neurotransmitters and monosynaptic connections to other cells. 3. Recent work on Lymnaea neurones suggests that calcium currents are depressed by volatile general anaesthetics applied in the clinical range, whilst evidence from other preparations indicates that there is a rise in intracellular calcium concentration following application of these substances. 4. Identified Lymnaea neurones have different responses to applied anaesthetics, irrespective of the anaesthetic used. Following application of halothane, barbiturates and several other anaesthetic agents, some cells gradually become quiescent after a short period, whilst in others a series of paroxysmal depolarizing shifts occur prior to quiescence. 5. Cultured neurones of Lymnaea, Helisoma and related species retain their characteristic action potential types and neurotransmitter identity. Their responses to anaesthetics are similar to those in the intact brain. They may also form synapses in culture. Thus, they are a useful tool for studying the cellular and subcellular actions of general anaesthetics.

Synthesis of methotrexate-antibody conjugates by regiospecific coupling and assessment of drug and antitumor activities

In order to increase the retention of drug activity, regiospecific coupling has been used to synthesize conjugates of methotrexate (MTX, 1) with normal rabbit IgG (NRG) and a mouse anti-human renal cancer monoclonal IgG (Dal K-20). MTX gamma-methyl ester (4) was produced either by selective esterification of MTX or by coupling of 4-amino-4-deoxy-N10-methylpteroic acid (2) with suitable glutamic acid derivatives. The MTX gamma-methyl ester (4) was then converted to the corresponding hydrazide 6. An amide-linked conjugate was formed when the MTX gamma-hydrazide (6) was converted to reactive acylating species 7 by using tert-butyl nitrite or trifluoroacetaldehyde, which were reacted with nucleophilic centers, presumably epsilon-amino groups, in native IgG. A hydrazone-linked conjugate was formed when MTX gamma-hydrazide (6) was reacted directly with IgG that had first been oxidized with periodate to form polyaldehyde IgG. The regiospecifically synthesized conjugates were somewhat more effective inhibitors in vitro of dihydrofolate reductase and of colony formation by human renal cancer (Caki-1) cells than were control nonregiospecific conjugates.

The effect of a high protein diet on leucine and alanine turnover in acid maltase deficiency

Leucine and alanine production rate was measured in 5 patients with acid maltase deficiency in the postabsorptive state, following 6 months on a normal diet with placebo and 6 months on an isocaloric high protein diet (16-22% protein). Whole body leucine production rate, a measure of protein degradation, expressed in terms of lean body mass was significantly greater than in five control subjects. Following the high protein diet, leucine production rate was decreased in four of the five patients but this was not statistically significant. Alanine production rate expressed in terms of lean body mass was significantly greater than in control subjects. After the high protein diet, alanine production rate and concentration were significantly decreased (p less than 0.05). There were no significant improvements in any of the clinically relevant variables measured in these patients. It is possible that a larger increase in protein intake over a longer time period may have a clinical effect.