A resonant sextuplet of sub-Neptunes transiting the bright star HD 110067

Planets with radii between that of the Earth and Neptune (hereafter referred to as 'sub-Neptunes') are found in close-in orbits around more than half of all Sun-like stars1,2. However, their composition, formation and evolution remain poorly understood3. The study of multiplanetary systems offers an opportunity to investigate the outcomes of planet formation and evolution while controlling for initial conditions and environment. Those in resonance (with their orbital periods related by a ratio of small integers) are particularly valuable because they imply a system architecture practically unchanged since its birth. Here we present the observations of six transiting planets around the bright nearby star HD 110067. We find that the planets follow a chain of resonant orbits. A dynamical study of the innermost planet triplet allowed the prediction and later confirmation of the orbits of the rest of the planets in the system. The six planets are found to be sub-Neptunes with radii ranging from 1.94R⊕ to 2.85R⊕. Three of the planets have measured masses, yielding low bulk densities that suggest the presence of large hydrogen-dominated atmospheres.

Bullous Systemic Lupus Erythematosus Successfully Treated With Intravenous Immunoglobulin and Mycophenolate Mofetil

Bullous systemic lupus erythematosus (BSLE) is a rare autoimmune blistering disorder of cutaneous lupus erythematosus (CLE) that typically manifests as an acute vesiculobullous eruption in a patient with systemic lupus erythematosus (SLE). Also, it can rarely present as the initial clinical manifestation of SLE. There is no established US Food and Drug Administration (FDA) therapy for BSLE. We report a case of a 71-year-old Hispanic woman with SLE and lupus nephritis classes III and V who presented to the hospital with a worsening rash with painful, ruptured blisters involving the upper arms, chest, and back. Our patient did not respond to topical or systemic steroids but improved rapidly to combination therapy with intravenous immunoglobulin (IVIg) and mycophenolate mofetil (MMF).

A detailed regimen of isotretinoin for the successful treatment of severe keratosis pilaris

Although a well-known recommended treatment option, there are currently no studies that describe the detailed regimen of isotretinoin for the treatment of primary keratosis pilaris. Based on previous studies involving other hyperkeratotic disorders, this report describes a safe and effective treatment course of isotretinoin for severe keratosis pilaris.

Aquaporin expression in the fetal porcine urinary tract changes during gestation

The expression of aquaporins (AQPs) in the fetal porcine urinary tract and its relation to gestational age has not been established. Tissue samples from the renal pelvis, ureter, bladder and urethra were obtained from porcine fetuses. Samples were examined by RT-PCR (AQPs 1-11), QPCR (AQPs positive on RT-PCR), and immunohistochemistry. Bladder samples were additionally examined by Western blotting. RNA was extracted from 76 tissue samples obtained from 19 fetuses. Gestational age was 60 (n=11) or 100 days (n=8). PCR showed that AQP1, 3, 9 and 11 mRNA was expressed in all locations. The expression of AQP3 increased significantly at all four locations with gestational age, whereas AQP11 significantly decreased. AQP1 expression increased in the ureter, bladder and urethra. AQP9 mRNA expression increased in the urethra and bladder, but decreased in the ureter. AQP5 was expressed only in the urethra. Immunohistochemistry showed AQP1 staining in sub-urothelial vessels at all locations. Western blotting analysis confirmed increased AQP1 protein levels in bladder samples during gestation. Expression levels of AQP1, 3, 5, 9 and 11 in the urinary tract change during gestation, and further studies are needed to provide insights into normal and pathophysiological water handling mechanisms in the fetus.

Long-term cultivation of a neuroblastoma cell line in medium with reduced serum content as a model system for neuronal aging?

Impaired energy metabolism and increased vulnerability to additional stress are some of the pivotal characteristics of the aging brain. This study was designed to establish a cell culture model for long-term investigations of some mechanisms underlying the process of aging using the neuroblastoma cell line SK-N-MC. As high serum concentrations in the culture medium are a major disadvantage for the investigation of regulatory or toxic influences, the effects of serum reduction in the culture medium on growth, viability and energy metabolism during long-term cultivation were determined. Serum reduction resulted in a decrease in the proliferation rate and in increased vulnerability of the cells, measured as release of lactate dehydrogenase into the culture medium. The rates of glucose consumption and lactate production were elevated, whereas the energetic state was markedly compromised, as was obvious from a 40% reduction of creatine phosphate. The observed increased vulnerability and the decreased energy state of the SK-N-MC cells were even more pronounced after induction of free radicals by addition of FeSO(4) to the medium with reduced serum content. Increased oxidative stress was indicated by elevated cellular contents of glutathione both after serum reduction and after incubation with FeSO(4). It is concluded that the SK-N-MC cells cultured chronically in medium with low serum content display biochemical characteristics that are similar to those observed in aging studies with animal models.

Central insulin resistance as a trigger for sporadic Alzheimer-like pathology: an experimental approach

A growing body of evidence implicates impairments in brain insulin signaling in early sporadic Alzheimer disease (sAD) pathology. However, the most widely accepted hypothesis for AD aetiology stipulates that pathological aggregations of the amyloid beta (Abeta) peptide are the cause of all forms of Alzheimer's disease. Streptozotocin-intracerebroventricularly (STZ-icv) treated rats are proposed as a probable experimental model of sAD. The current work reviews evidence obtained from this model indicating that central STZ administration induces brain pathology and behavioural alterations resembling those in sAD patients. Recently, alterations of the brain insulin system resembling those in sAD have been found in the STZ-icv rat model and are associated with tau protein hyperphosphorylation and Abeta-like aggregations in meningeal vessels. In line with these findings the hypothesis has been proposed that insulin resistance in the brain might be the primary event which precedes the Abeta pathology in sAD.

Brain antioxidant capacity in rat models of betacytotoxic-induced experimental sporadic Alzheimer's disease and diabetes mellitus

It is believed that oxidative stress plays a central role in the pathogenesis of metabolic diseases like diabetes mellitus (DM) and its complications (like peripheral neuropathy) as well as in neurodegenerative disorders like sporadic Alzheimer's disease (sAD). Representative experimental models of these diseases are streptozotocin (STZ)-induced diabetic rats and STZ-intracerebroventricularly (STZ-icv) treated rats, in which antioxidant capacity against peroxyl (ORAC(-ROO)*) and hydroxyl (ORAC(-OH)*) free radical was measured in three different brain regions (hippocampus, cerebellum, and brain stem) by means of oxygen radical absorbance capacity (ORAC) assay. In the brain of both STZ-induced diabetic and STZ-icv treated rats decreased antioxidant capacity has been found demonstrating regionally specific distribution. In the diabetic rats these abnormalities were not associated with the development of peripheral diabetic neuropathy. Also, these abnormalities were not prevented by the icv pretreatment of glucose transport inhibitor 5-thio-D-glucose in the STZ-icv treated rats, suggesting different mechanism for STZ-induced central effects from those at the periphery. Similarities in the oxidative stress alterations in the brain of STZ-icv rats and humans with sAD could be useful in the search for new drugs in the treatment of sAD that have antioxidant activity.

From benefit to damage. Glutamate and advanced glycation end products in Alzheimer brain

The glutamatergic system is the most widespread neurotransmitter system in the mammalian brain. It is connected to the acetylcholinergic neurotransmitter system to form the glutamatergic/aspartatergic-acetylcholinergic circuit, which is the morphobiochemical basis of learning, memory and cognition assisted by the glutamatergic N-methyl-D-aspartate receptor, which mediates long-term potentiation as the fundamental molecular mechanisms of these mental capacities. Glutamate and acetylcholine as ligands of the two neurotransmitter systems are products of the neuronal glucose metabolism as holds true also for advanced glycation end products (AGEs), which are markers of damaged and/or aged proteins. During normal aging, both the neurotransmitters glutamate and acetylcholine undergo strong functional variations. Their synthesis was found to be reduced as a common feature. In contrast, basal release of acetylcholine and receptor number decrease, whereas basal release of glutamate and receptor number increase. AGEs increase during aging obviously preferentially in glutamatergic pyramidal neurons in cerebral cortical layers prone to neurodegeneration. In sporadic Alzheimer disease (SAD), glutamate concentration was shown to fall since it may serve as a substitute for lacking glucose in the beginning of the disease. In contrast, glutamate receptor density was found to be much less involved indicating an excessive activation of the glutamatergic neurotransmitter system particularly via the NMDA receptor, mediating endogenous excitotoxicity. The morphological hallmarks of SAD neuritic plaques and neurofibrillary tangles have been demonstrated to crosslink with AGEs causing an increased rate of free radical production. First data from animal studies and investigations on human beings may indicate that the NMDA receptor antagonist memantine may have beneficial effects on the course of SAD and its clinical symptoms.

Alois Alzheimer revisited: differences in origin of the disease carrying his name

Based on the means of his time, Alois Alzheimer supposed that the disease, later carrying his name, is a disease of older age, and that the pathomorphological structures he described are due to disturbances in brain metabolism. In this contribution, it is discussed which cellular metabolic abnormalities may be representative for age-related sporadic Alzheimer disease (SAD) the predominant form of SAD in contrast to the very rare hereditary early-onset form. In focus are disturbances in glucose/energy metabolism which involve the deficits in acetylcholine, cholesterol and UDP-N-acetylglucosamine beside ATP. Another leading abnormality is the defect in cell membrane composition. The interrelation between abnormal glucose/energy metabolism and membrane defect may be assumed to form the basis for the induction of both the perturbed metabolism of the amyloid precursor protein leading to increased formation of beta-amyloid and hyperphosphorylation of tau-protein destroying cell structures. Alois Alzheimer may have been so prescient to assume most of this 100 years ago.

Differentiated effect of ageing on the enzymes of Krebs’ cycle, electron transfer complexes and glutamate metabolism of non-synaptic and intra-synaptic mitochondria from cerebral cortex

The effect of ageing on the activity of enzymes linked to Krebs' cycle, electron transfer chain and glutamate metabolism was studied in three different types of mitochondria of cerebral cortex of 1-year old and 2-year old male Wistar rats. We assessed the maximum rate (V(max)) of the mitochondrial enzyme activities in non-synaptic perikaryal mitochondria, and in two populations of intra-synaptic mitochondria. The results indicated that: (i) in normal, steady-state cerebral cortex the values of the catalytic activities of the enzymes markedly differed in the various populations of mitochondria; (ii) in intra-synaptic mitochondria, ageing affected the catalytic properties of the enzymes linked to Krebs' cycle, electron transfer chain and glutamate metabolism; (iii) these changes were more evident in intra-synaptic "heavy" than "light" mitochondria. These results indicate a different age-related vulnerability of subpopulations of mitochondria in vivo located into synapses than non-synaptic ones.

Central administration of alloxan impairs glucose tolerance in rats

By means of oral glucose tolerance test (OGTT), we investigated glucose tolerance in rats pre-treated with intracerebroventricular and subcutaneous non-diabetogenic dose of betacytotoxic drug alloxan 7 days before OGTT. Being normoglycemic and normoinsulinemic pre-OGTT, at 30 minutes post-OGTT, alloxan intracerebroventricularly-treated rats had a lower glucose and a higher insulin plasma levels in comparison with controls or alloxan subcutaneously treated animals. Centrally administered alloxan seems to have brain related effect on the regulation of peripheral glucose tolerance and insulin secretion.

Odour and taste sensitivity is associated with body weight and extent of misreporting of body weight

BACKGROUND

Sensory factors are important determinants of appetite and food choices but little is known about the relationship between body weight and sensory capabilities.

OBJECTIVE

To investigate the relationship between measured body weights, misreporting of body weight and sensory capabilities.

DESIGN

In a cross-sectional sensory study, body weight was assessed by measured and self-reported body weight in healthy men (n=130) and women (n=181). Sensory capabilities were assessed as odour detection and identification, and detection for salty, sweet, sour and bitter taste.

RESULTS

Odour detection, odour identification and taste perception scores were lower in subjects with a BMI >or=28 kg/m(2) than in subjects with a BMI <28 kg/m(2) in the age group <65 years whereas in subjects >or=65 years scores were higher in subjects with a BMI >or=28 kg/m(2) than in subjects with a BMI <28 kg/m(2) (BMI*age group: P=0.015, 0.053 and 0.015, respectively). Independent of age, scores were highest in under reporters of body weight (P=0.008, 0.001 and 0.017). Differences in taste perception could be attributed to sour (P=0.015) and bitter (P=0.026) perception, but not to salty or sweet perception.

CONCLUSION

Relationship between sensory capabilities and body mass is age dependent. Compared to overweight subjects, the sensory capabilities of normal weight individuals appear to be higher (<65 years) and lower (>or=65 years). At any age, however, subjects who under reported their body weight show higher sensory capabilities.

Drug and alcohol use among patients admitted to a Danish trauma centre: a prospective study from a regional trauma centre in Scandinavia

OBJECTIVES

The incidence of drug and alcohol use is unknown among Danish trauma patients, and has not been thoroughly investigated in Europe.

METHODS

Patients admitted to the regional trauma centre in Aarhus, Denmark, were prospectively screened by blood and urine tests for the presence of alcohol, and legal and illicit drugs. The correlation with the Injury Severity Score, hospitalization time, and mortality after drug or alcohol intake was investigated.

RESULTS

A quarter of all patients admitted in 1999 and 2000 had an alcohol level exceeding the national legal driving limit of 50 mg/dl, and one or more drugs were found in one in five patients. The presence of any drug or alcohol correlated positively with the Injury Severity Score, whereas alcohol level, hospitalization time, and mortality did not correlate.

CONCLUSION

The rate of trauma patients with a blood serum level of alcohol greater than 100 mg/dl was similar to a previous European study and to US studies. The prevalence of drugs was less, and benzodiazepines were the most used group of drugs in our study. The routine screening of Danish trauma patients in order to implement preventative measures may be beneficial.

Short-term mental activation accelerates the age-related decline of high-energy phosphates in rat cerebral cortex

Aging in rats is associated with a significant decline in brain levels of energy-rich phosphates, including ATP and creatine phosphate. To test the effects of transient mental activity mediated by psychometric testing, and of metabolic inhibition of pyruvate dehydrogenase (PDH) (an enzyme complex that generates acetyl coenzyme A (CoA) to feed the mitochondrial tricarboxylic acid cycle), we compared adult (52 to 64-week-old) and aged (104-week-old) rats with and without intracerebral injections of the PDH inhibitor, bromopyruvate (BP), in the presence and in the absence of extensive psychometric testing by standard passive avoidance and hole board test paradigms. As compared with mental rest, short-term mental activation was associated with higher levels of energy-rich phosphates in the cerebral cortex of both adult and aged animals, but did not prevent the age-dependent decline in these phosphates. ATP turnover was markedly increased by mental activity, but was less pronounced in aged animals. In the hippocampus, less marked changes in the energy pool became obvious. The abnormalities in energy metabolism indicate an age-dependent and stress-accentuated reduction of the capacity to meet such energy-dependent demands as mixed function oxidation in the aged brain. BP did not change brain levels of energy-rich phosphates, indicating that the damage caused by decreased PDH activity can be compensated for both in adult and in aged animals.

Age-related histochemical staining patterns of glycosaminoglycans in cell nuclei of different regions of the rat brain: a pilot study

The brains of 6 rats aged 12 months (adult) and 6 rats aged 24 months (aged) were embedded in paraffin following steady state perfusion with fixation solution. Glycosaminoglycans (GAGs) were demonstrated by histochemical methods using the Alcian blue CEC method in combination with the Feulgen reaction and testis hyaluronidase. Cell nuclei revealed different patterns of GAGs in different layers of the brain cortex and in different cell types. In neuronal cell nuclei of layer 2, no GAGs are found and this may be the case also in certain types of pyramidal cells. There was a reduction of the blue staining components of the chromatin network by hyaluronidase, and also a reduction of the electronmicroscopic contrast by this enzyme in pilot study using a specimen of one animal. The enzyme effects were found to be more marked or even exclusively present in the group of aged animals. Thus, the contents of chrondroitin sulfates or hyluronate which are substrates of the enzyme may be increased either relatively or absolutely in cell nuclei of aged brains whereas GAGs resistant to the enzyme may be reduced in activity. Since GAGs are known to influence DNA activity, the variations demonstrated may be assumed to be of significance for the aging process in postmitotic cells.

Relationship between cerebral energy metabolism in parietotemporal cortex and hippocampus and mental activity during aging in rats

The present investigation demonstrates differences in both formation and utilization of the energy-rich compounds adenosine triphosphate ATP and creatine phosphate (CrP) in behaviorally well and poorly performing inbred male Wistar rats in parietotemporal cerebral cortex and hippocampus with aging from 1 to 2ys. Also, differences in learning and memory capacities (behavior) became obvious. By holeboard testing, good (GP) and poor performers (PP) have been discriminated. The pools of energy-rich phosphates as determined in parietotemporal cerebral cortex and in hippocampus under resting conditions were found to be reduced by nearly 10% for both creatine phosphate and the whole available energy pools in PP as compared to GP. Aging from 1 to 2y diminished the concentrations of energy-rich phosphates in the cerebral areas studied and in both GP and PP under resting conditions. Additionally, an age-related aggravation of the energy deficit became obvious between GP and PP. Repeated mental activation from 1y to 2y resulted in the maintenance of improvement as registered for the mean run time and the number of visited/revisited holes in GP. In contrast, PP deteriorated (mean run time), and could not maintain improvement (number of visited/revisited holes) over time. Repeated mental activation normalized the energy pool by increased formation of the energy-rich compounds ATP and CrP in both cerebral areas studied in GP and PP. However, differences became obvious between GP and PP. The energy-turnover in the latter group was found to be significantly reduced for both cerebral areas studied. GP could meet the enhanced energy demand of mental activation during aging by increasing formation and utilization of energy. PP could increase energy formation but were unable to sufficiently adapt energy utilization under the same conditions. This disturbance in energy metabolism may have impacts on energy-consuming processes in PP which may contribute to the markedly reduced cognitive reserve in PP. In human beings, PP approximately poorly educated people found to be prone to sporadic Alzheimer disease.

Gene expression profile in streptozotocin rat model for sporadic Alzheimer?s disease

Sporadic Alzheimer's disease (SAD), a progressive neurodegenerative disease, is the most common cause of dementia. The etiology of the disease is still unknown, but it is suspected to be a concert of genetic and environmental factors. Intracerebroventricular injection of streptozotocin (STZ), which inhibits insulin receptor function, develops long-term and progressive deficits in learning, memory and cognitive behavior as well as biochemical changes and neuronal degeneration in rats similar to SAD. Micro-array analysis provides a genome-wide, non-biased study of gene expression patterns. The aim of this study was to investigate the gene expression pattern in the STZ animal model for SAD. RNA from rat cortex, striatum and cerebellum were analyzed for gene expression pattern via Affymetrix neurobiology chip-array and confirmed by real-time RT-PCR. Genes such as potassium channels, GABA receptors and glutamate transporter were up regulated, while insulin-like growth factor receptor was down regulated in STZ rats. These pathways may reveal molecular events causing the neuronal death in SAD.

[Pathomechanisms and hypothesis-guided therapeutic strategies for late-onset Alzheimer's disease]

Even though the clinical effectiveness of the presently used pharmaceutical therapy of sporadic Alzheimer Disease seems to be proven sufficient, their effective mechanisms are much less known or are disregarded in the evaluation of the clinical effects. However, it seems to be inevitable to know both clinical effect and effective mechanisms of pharmaceutics in order to be able to judge their adversity and benefit. In reference to the pharmaceutics implemented on sporadic AD in Germany, total different effective mechanisms are shown. In consideration of the shown pathomechanisms which have been recognized for sporadic AD, therapeutic rationales on application of Ginkgo biloba extract (EGb 761) and Memantine are evident. The application of acetylcholinesterase inhibitors, often looked on as agent of choice, is to be considered critically because of the danger of the occurrence of myopathological dysfunction, resp. the Gulf War Syndrome. Sophisticated and hastily advertised therapy strategies with statins or vaccination against beta A4 should not be used because of a lack of sufficient evidence based on the pathophysiological pattern of damage as known in sporadic AD. Future development must take in account that with sporadic AD aging influences cannot or can hardly be influenced. Therapeutic goals should consist to improve the cellular energy status and the membrane functioning.

Memory function and brain glucose metabolism

Memory formation and memory retrieval are subject to complex cellular and molecular processes. Increasing evidence exists that neuronal glucose metabolism and its control by the insulin signal transduction cascade are the main players in such processes. Acetylcholine synthesis depends on the availability of acetyl CoA, provided from glucose breakdown, and insulin, which controls the activity of acetylcholine transferase. ATP is necessary for both synaptic activity and plasticity. This is also true for APPs, the secreted derivative of APP. Trafficking of the latter protein is controlled by insulin and insulin receptor function also acting on activity-regulated cytoskeleton-associated gene expression, which induces biochemical stimuli involved in synaptic activity and plasticity. Any damage in neuronal glucose metabolism and its control may, therefore, cause disturbances in memory function--as is found for example in sporadic Alzheimer's disease. Mimicking these metabolic and behavioral abnormalities in experimental animals, it was found that EGb 761 (definition see editorial) shows beneficial effects both on brain glucose and energy metabolism and on behavior.

Malaria dipsticks beneficial for IMCI in Cambodia

OBJECTIVES

The Integrated Management of Childhood Illness (IMCI) approach and new clinical treatment guidelines to control malaria among children less than 5 years old were introduced recently in Cambodia. This study was conducted to finalize the malaria part of the national IMCI fever chart.

METHODS

A total of 323 sick children 2-59 months old were studied at rural health centres in northern Cambodia from February to April 2000. Cases with fever (by axillary temperature or history) or anaemia (by palmar pallor) were tested with dipsticks for Plasmodium falciparum and Plasmodium vivax in high and low malaria risk areas and, if positive, treated with anti-malarials.

RESULTS

The draft IMCI chart identified children with malaria safely and effectively (sensitivity 14 of 15, approximately 93% and specificity 292 of 308, approximately 95%). The study confirmed the potential of malaria dipsticks as a part of IMCI case management.

CONCLUSION

The Cambodian Ministry of Health will use the studied malaria chart during the Early Implementation Phase of IMCI. Dipsticks able to detect P. falciparum and P. vivax with high sensitivity and acceptable cost will be needed for this purpose. To promote the rational use of dipsticks, the National Centre for Malaria Control, Parasitology and Entomology (Centre National de Malaridogie, Parasitologie et Entomologie, CNM) should list all known malaria risk areas in the country and prepare detailed local maps guiding case management especially in transitional zones.

ATPases of synaptic plasma membranes from hippocampus after ischemia and recovery during ageing

Plasticity and relationships between individual ATPases linked to energy-utilizing systems of hippocampus, a very sensitive functional area to both age and ischemia, were studied during ageing on synaptic plasma membranes of 1-year-old "adult" and 2-year-old "aged" rats after 15 min of complete cerebral ischemia and different reperfusion times (01, 24, 48, 72, and 96 h). Activities of Na+, K+, Mg(2+)-ATPase, Mg(2+)-ATPase ouabain insensitive, Na+, K(+)-ATPase, "direct" or "basal" Mg(2+)-ATPase, and acetylcholinesterase (AChE) were evaluated in synaptic plasma membranes, where they play the major role in the regulation of presynaptic nerve ending homeostasis. This in vivo study of recovery time-course from 15 mins of cerebral ischemia indicated specific biochemical assessments of functional meaning: (a) Na+K(+)-ATPase of synaptic plasma membranes in adult and aged animals is stimulated by ischemia; (b) this "hyperactivity" is more markedly related to adult than to aged animals; (c) these abnormalities still persist after 72 and 96 h during the recirculation times, indicating the delayed postischemic suffering of the brain; (d) specific Mg(2+)-ATPase enzyme system possess a lower catalytic power in aged animals than in adult ones, but remained unaltered in adult animals by ischemia and reperfusion; (e) Mg(2+)-ATPase is stimulated in aged animals by ischemia, further increasing during reperfusion up to 72-96 h, indicating the delayed hyperactivity of hippocampus; (f) the increased metabolic activity of hippocampus is indicated by the increased activity of cholinergic system; (g) integrity of synaptic plasma membranes seems not to be altered by 15 min ischemia to a critical extent to compromise their catalytic functionality during reperfusion; (h) AChE activity increases in both adult and aged at some survival times. There are logical reasons for the hypothesis that the modifications in ATPase's catalytic activities in synaptic plasma membranes, which have been modified by ischemia in presynaptic terminals, may play important functional role during recovery time in cerebral tissue in vivo, especially as regards its responsiveness to noxious stimuli, particularly during the recirculation period from acute (or chronic) brain injury.

[Etiologic and pathogenetic heterogeneity of Alzheimer disease]

The present review discusses whether the clinically and pathologically uniform phenotype of Alzheimer's disease (AD) consists of different subtypes with respect to etiopathogenesis. In a minority of patients with AD, the disease is determined by mutations of genes on chromosomes 1, 14, and 21. The amyloid cascade hypothesis provides a conclusive model for etiopathogenesis of these cases. The majority of patients, however, suffer from the sporadic subtype of AD, the etiopathogenesis of which is presently unknown. This subtype's pathogenesis is determined by a cascade of events, among which age, a disturbance of neuronal insulin receptor function leading to a deficit in acetylcholine and available energy, and membrane instability are the most important factors. The effects of these factors are modulated by the presence or absence of apolipoprotein E4. Thus, the development of this form of AD is characterized by dynamic cellular biological changes in the brain which are independent of the metabolism of the amyloid precursor protein and genetic factors. Therefore, the sporadic subtype of AD may be regarded as an age-associated metabolic disease of the brain.

Effect of Ginkgo biloba extract (EGb761) on glucose metabolism-related markers in streptozotocin-damaged rat brain

To reveal whether an extract of Ginkgo biloba (EGb761) may affect streptozotocin (STZ)-induced impairments in brain glucose metabolism, autoradiographies of [3H]cytochalasin-B binding to the total population of glucose transporters, [125I]insulin binding to insulin receptors, [3H]glyburide binding to sulfonylurea receptors, and radioactive in situ hybridization for GLUT3 mRNA were carried out in hippocampal brain sections of adult rats that have additionally been divided into good performers (GP) and poor performers (PP) by behavioural tests before the experiments. The STZ-induced increases in hippocampal [3H]cytochalasin-B binding to (total) glucose transporters returned to almost normal values following EGb761 treatment, regardless of the experimental animal group (GP or PP) tested. Similarly, the STZ-mediated enhancements in hippocampal insulin receptor binding of GP rats were partially compensated by the treatment with EGb761. The data suggest beneficial effects of EGb671 on impaired brain glucose metabolism, at least under the experimental conditions used in the study presented.

The brain insulin signal transduction system and sporadic (type II) Alzheimer disease: an update

Nosologically, Alzheimer disease may not be considered to be a single disorder in spite of a common clinical phenotype. Only a small proportion of about 5% to 10% of all Alzheimer cases is due to genetic mutations (type I) whereas the great majority of patients was found to be sporadic in origin. It may be assumed that susceptibility genes along with lifestyle risk factors contribute to the causation of the age-related sporadic Alzheimer disease (type II). In this context, the desensitization of the neuronal insulin receptor similar to not-insulin dependent diabetes mellitus may be of pivotal significance. This abnormality along with a reduction in brain insulin concentration is assumed to induce a cascade-like process of disturbances including cellular glucose, acetylcholine, cholesterol, and ATP associated with abnormalities in membrane pathology and the formation of both amyloidogenic derivatives and hyperphosphorylated tau protein. Sporadic Alzheimer disease may, thus, be considered to be the brain type of diabetes mellitus II. Experimental evidence is provided and discussed.

Inhibition of the neuronal insulin receptor. An in vivo model for sporadic Alzheimer disease?

It has been hypothesized that a central even in the early pathogenesis of sporadic Alzheimer disease (SAD) is the dysfunction of the neuronal insulin receptor signal transduction. To prove this, this receptor was inhibited by a triplicate icv application of STZ. Insulin binding sites were upregulated as in SAD. With respect to glucose transport proteins, detailed investigations are necessary.

Brain glucose and energy metabolism abnormalities in sporadic Alzheimer disease. Causes and consequences: an update

It is discussed that Alzheimer disease does not form a nosologic entity. 5 to 10% of all Alzheimer cases are due to inherited abnormalities on chromosomes 1, or 14, or 21, whereas the majority of 90-95% is sporadic in origin. Age-related changes in the composition of membranes and in glucose/energy metabolism along with a sympathetic tone in the brain are assumed to be cellular/molecular risk factors for this disease. In its pathogenesis, the desensitization of the neuronal insulin receptor similar to non-insulin dependent diabetes mellitus may be of pivotal significance. This abnormality along with a reduction in insulin concentration is assumed to induce a cascade-like process of disturbances including decreases in cellular glucose, acetylcholine, cholesterol, and ATP, associated with changes in the metabolism of amino acids and fatty acids. There is evidence that the reductions in the availability of both glucose/energy and insulin contribute to the formation of amyloidogenic derivatives and hyperphosphorylated tau protein. This may indicate that the amyloid cascade hypothesis in not valid for sporadic Alzheimer disease but that the formation of both, amyloidogenic derivatives and hyperphosphorylated tau protein is downstream the origin of this neurodegenerative disease.

Successful breast-feeding as a result of a health education programme for mothers

The present study aims to prove an improvement in breast-feeding practices in mothers who received written instructions for successful breast-feeding and had individual counselling at the time of taking this questionnaire. The instructions were based on the results of a study carried out in Slovenia in 1993 and published in the Journal of Advanced Nursing (1998), 27, 1250-1256 (Hoyer & Pokorn 1998). The variables that were then found statistically significant in the initial and continued breast-feeding became the basis of written instructions for breast-feeding. The results obtained in the new current study were compared with that basic study which included 881 mothers. This was possible because the conditions of breast-feeding between 1993 and 1995 (when the new study was launched) had not changed. The idea of baby-friendly hospital initiative (BFHI) had not yet come into force in Slovenia. The current study comprised 203 pregnant women who were first visited during their 8th month of pregnancy. In order to collect data on breast-feeding and deliver instructions, a field nurse visited each mother eight times until the completion of first year and continued to visit them every third month and for all those who were still breast-feeding after that time, until the end of the lactation period. Statistical analysis was carried out by means of SPSS statistical package and survival analysis. All mothers in the study started breast-feeding. By the end of the first month 84.7% of them were still breast-feeding, while by the end of the third month it dropped to 74.9%, and by the end of the sixth month to 45.8%. Among these, breast-feeding alone was practised in the first week by 25.7%, by the end of the first month by 16.4%, and by the end of the third month by 9.5%. All the observed parameters were better than in the basic study. The mean duration of breast-feeding was 217 days, while the longest duration was 852 days. The survival analysis showed a statistically significant difference in the duration of breast-feeding. In the current study group, mothers weaned their infants at a slower rate than in the group from the year 1993. It has been found that the written instructions as well as personal encouragement by the field nurse exerted a favourable influence on breast-feeding practices, which was taken as a guideline for our further professional work and change of standards in the field of breast-feeding promotion.

Effects of low-level lead on glycolytic enzymes and pyruvate dehydrogenase of rat brain in vitro: relevance to sporadic Alzheimer's disease?

Lead is known to be a potent inhibitor of many enzymes working in the brain, thus possibly inducing functional problems in the brain under pathophysiological conditions. Among such enzymes are those involved in glucose metabolism and energy production. We investigated the inhibitory effects of low-level lead on brain hexokinase (HK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PK) and pyruvate dehydrogenase complex (PDHc) with rat brain homogenate. PDHc was distinctively inhibited when low-dose lead acetate was added last of all (IC50 = 5 microM) to the reaction mixture. The other enzymes were completely resistant to 5 microM of lead acetate. When the homogenate was preincubated with lead acetate HK was dramatically inhibited by low-level lead acetate (1-5 microM), in a manner dependent on both preincubation time and lead concentration. However, the inhibitory effect was abolished by coincubation with its substrates, glucose or ATP. The results suggest that exposure to low levels of lead may increase the risk of cerebral hypometabolism caused by direct inhibition of specific glucose-utilizing enzymes. In this context, lead might be regarded as a risk factor in the abnormal glucose metabolism seen in some kinds of neurodegenerative disorders such as sporadic Alzheimer's disease.

Increase in vulnerability of middle-aged rat brain to lead by cerebral energy depletion

The neurotoxic effects of low-level lead (Pb) during senescence are increasing interests of importance. We investigated the effects of low-level Pb on the brain in a normal condition and a pathophysiological condition of energy shortage that is commonly found in age-related neurological diseases. Middle-aged rats (15 months old) were exposed to 200 mg/l Pb acetate in drinking water for 2 months and thereafter received bilateral intracerebroventricular injections of streptozotocin (STZ). After 1 month's additional exposure to the same level of Pb solution as before the rats were sacrificed. Blood and brain Pb levels were measured by graphite furnace atomic absorption spectrophotometry. Energy-rich phosphate levels in the brain were determined by high-performance liquid chromatography equipped with a UV detector. Astroglial activation and glucose-regulated protein (GRP)94 expression were examined immunohistochemically. Exposure to Pb increased the blood Pb level to 10.8 microg/dl and the brain Pb level to 0.052 microg/g. But a significant additional increase in the brain Pb level, to 0.101 microg/g, became obvious in rats treated with Pb + STZ. Both Pb and STZ induced perturbation in brain energy metabolism, but no further alteration in energy metabolite levels was found in rats treated with Pb + STZ. Astroglial activation and GRP94-positive astrocytes and neurons were found only in the brains of Pb + STZ-treated rats. These results suggest that exposure to low-level Pb can perturb brain energy metabolism and the brain becomes more vulnerable to Pb when it is under energy stress.

Chronic exposure to low-level lead impairs learning ability during aging and energy metabolism in aged rat brain

The neurotoxic effect of chronic exposure to low-level lead (Pb) with advancing age is becoming an important social issue of public health. To examine the effects of low-level Pb treatment on behavior, cognition and brain energy metabolism in aging, we administered 200 ppm Pb acetate to adult (10-month-old) male Wistar rats for 12.5 months. After 12.5 months' exposure, the mean Pb levels in blood and brain had increased to 17.5 µg/dl and 0.07 µg/g, respectively, and the rats showed impaired learning and memory functions in a holeboard spatial memory test. No significant difference was found between experimental and control groups in locomotor activity and passive avoidance tests. By HPLC analysis of energy-rich phosphate concentrations, mild abnormalities were found in parietotemporal cortex and hippocampus, but only the 4.4% decrease of ATP in the parietotemporal cortex was statistically significant. These results suggest that chronic exposure to Pb during aging stage may selectively impair learning and memory functions and may cause slight cerebral energy impairment.

Linear relation between cerebral phosphocreatine concentration and memory capacities during permanent brain vessel occlusions in rats

The present study investigates the interrelation between cerebral energy state and memory capacities in a rat model of stepwise cerebral vessel occlusions. After acute and subchronic permanent vessel occlusions, cortical energy metabolites (ATP, phosphocreatine, ADP, AMP) were detected by high-pressure liquid chromatography (HPLC) analysis, and the effects on learning, memory, and cognitive behavior were evaluated using a hole-board test. The results of the study demonstrated a drastic decrease in energy-rich phosphates by 33% for phosphocreatine and by 44% for ATP after acute vessel occlusions. In addition, rat working and reference memories were strikingly decreased to about 5% of controls. In contrast, two weeks after four-vessel occlusion, the energy state was almost completely restored to control levels. However, a significant decrease in memory capacities was observed in subchronic state. In summary, this study has demonstrated a close linear relationship (p < 0.001) between an impaired cerebral energy state and brain memory dysfunction after acute and permanent cerebral four-vessel occlusion. Thus, this animal model of stepwise reduction of the cerebral blood supply may reflect some clinically relevant processes occurring during cerebrovascular and neurodegenerative diseases.

A disturbance in the neuronal insulin receptor signal transduction in sporadic Alzheimer's disease

Disturbances of glucose and energy metabolism are hypothesized as pathogenetic factors in sporadic dementia of Alzheimer type (SDAT). Insulin and is receptors play an important role in the regulation of brain glucose metabolism and neuronal growth. In postmortem brain cortex in SDAT, the densities of brain insulin receptors were decreased compared to adult controls, but were increased in relation to aged controls. Tyrosine kinase activity, a signal transduction mechanism common to insulin and IGF-1 receptors, was reduced in SDAT in comparison to middle-aged and age-matched control groups. The data are consistent with a neurotrophic role of insulin in the human brain and an upregulation of insulin receptors is SDAT brain as a compensatory mechanism, possibly due to impaired signal transduction mechanism.

Damaged neuronal energy metabolism and behavior are improved by Ginkgo biloba extract (EGb 761)

The standardized extract EGb 761 from the dried green leaves of Ginkgo biloba is a complex mixture of ingredients with an uniquely broad spectrum of pharmacological activities on the central nervous system e.g. in memory enhancing properties and in the regulation of cerebral glucose/energy metabolism. To test these effects on both behavioral and metabolic brain parameters, the animal model of intracerebroventricular (i.c.v.) streptozotocin (STZ) treatment was used. To quantify the experimental data more precisely, animals that were good performers were separated from poor performers by means of the holeboard test before i.c.v. administration of STZ. Good performers only were considered for the study. After a 1-week training period on the holeboard improvement was seen in all animals in learning, memory and cognition, and the improvement was maintained over the investigation period of 12 weeks in the control group. In this group, the energy pool in the cerebral parietotemporal cortex was found to be large and the energy turnover high. After triplicate i.c.v. STZ injection, working memory (WM), reference memory (RM), and passive avoidance (PA) behavior fell off and continued to deteriorate throughout the investigation period. Otherwise there were no significant differences in locomotor activity, excluding the possibility that activity per se might have contributed to the behavioral abnormalities. These were accompanied by a permanent deficit in cerebral energy metabolism. The ongoing deterioration in behavior and the maintained deficit in cerebral energy metabolism occurring after a triplicate i.c.v. STZ injection were significantly slowed down by EGb761. The deficits in learning, memory and cognition were partially compensated, and the disturbances in cerebral energy metabolism returned to almost completely normal values. These findings underscore the beneficial effect of EGb761 that had been reported in dementia disorders.

Brain-derived neurotrophic factor improves long-term potentiation and cognitive functions after transient forebrain ischemia in the rat

We investigated the effect of brain-derived neurotrophic factor (BDNF) on hippocampal long-term potentiation (LTP) and cognitive functions after global cerebral ischemia in the rat. After four-vessel occlusion, BDNF was administered via an osmotic minipump continuously over 14 days intracerebroventricularly. Electrophysiological experiments were performed 14 days after cerebral ischemia. Test stimuli and tetanization were delivered to the Schaffer collaterals of the hippocampus and field excitatory postsynaptic potentials (fEPSP) were recorded in the CA1 region. Cognitive impairment was analyzed repeatedly with a passive avoidance test, a hole-board test, and with an activity center on the same animal. In sham-operated animals, LTP was consistantly induced after delivering a tetanus (increase of initial slope of fEPSP to 173 +/- 12% of baseline; n = 6). After transient forebrain ischemia LTP could not be induced (117 +/- 4% of baseline; n = 7). In ischemic animals treated with BDNF, LTP could be induced (168 +/- 28% of baseline; n = 8). Transient forebrain ischemia resulted in a significant decrease in spatial discrimination performance but not of associative memory. The ratios for working memory (WM) and reference memory (RM) 15 days after ischemia were lower in the ischemic rats (n = 10) than in the sham-operated control animals (n = 10; WM: 22 +/- 6 vs 72 +/- 7; RM: 30 +/- 7 vs 72 +/- 5). Postischemic intracerebroventricular BDNF infusion increased both WM (63 +/- 4; n = 10) and RM (58 +/- 5; n = 10). The spontaneous locomotor activity did not differ significantly in the three groups. These data indicate a protective effect of BDNF for synaptic transmission and cognitive functions after transient forebrain ischemia.

Interrelation between cerebral energy metabolism and behaviour in a rat model of permanent brain vessel occlusion

The present study investigates the interrelation between cerebral energy metabolism and memory capacities after acute and permanent occlusions of carotid and vertebral arteries in adult Wistar rats (n=60). Tissue ATP, phosphocreatine, ADP, AMP and adenosine concentrations were determined in rat brain by high-pressure liquid chromatography (HPLC) analysis. Lactate and pyruvate were measured spectrophotometrically. Rats underwent psychometric testing by means of a holeboard test, closed field activity, and passive avoidance behaviour. Acute cerebral ischaemia was associated with a substantial deficit in energy load (-50%). Cortical adenosine and lactate exhibited a 7- and a 10-fold increase, respectively, in concentration. After 2 weeks of four-vessel occlusion, cortical ATP and phosphocreatine showed a partial enhancement in their concentrations if compared with acute ischaemia. Consequently, energy load (micromol/g) increased from 0.59 to 1.42 in cerebral cortex and from 0.58 to 1.14 in hippocampus under conditions of acute and permanent ischaemia, respectively. While lactate was normalized, adenosine showed a 2-fold increase in its cortical concentration. All animals improved their abilities in learning, memory and cognition after a 7-day training period. Acute vessel occlusion severely decreased working memory (WM), reference memory (RM) and locomotor activity. Simultaneously, the passive avoidance test showed a significant reduction in latency time from 247+/-85 s (sham) to 145+/-132 s. The partial improvement in brain energy state was accompanied by a relative improvement in WM and RM, although both memory capacities remained significantly lower than in controls. The data of the present study demonstrate a linear relationship between cerebral energy metabolism and brain memory capacities after acute and permanent vessel occlusions in rats.

Streptozotocin increases free fatty acids and decreases phospholipids in rat brain

Streptozotocin (STZ) is a diabetogenic drug that disrupts glucose and energy metabolism in brain. To study its effect on brain lipids, tissue concentrations of free fatty acids and phospholipids were measured in the temporal cortex and the hippocampus of adult rats 3 weeks after a single intracerebroventricular (icv) injection of STZ. STZ increased concentrations of palmitic acid and stearic acid in temporal cortex and these of arachidonic acid both in the anterior part of the hippocampus and in CA1. In addition, palmitic acid and stearic acid concentrations were elevated in the anterior hippocampus. In contrast, STZ decreased brain cortex levels of phosphatidylethanolamine and phosphatidylserine. These data show that STZ alters brain lipid metabolism. They suggest that oxidative phospholipid breakdown is accelerated by STZ. These changes may be related to decreased brain glucose utilization and energy formation.