Effects of dipalmitoylphosphatidylcholine liposomes on high affinity transport of choline and synthesis of acetylcholine in cerebral cortical synaptosomes in the rat

The presynaptic cholinergic effects of the phospholipid dipalmitoylphosphatidylcholine were investigated in non-depolarized synaptosomes from the cerebral cortex of the rat. This naturally-occurring phospholipid, in the form of small unilamellar vesicles (3.0 mg/ml), inhibited both high affinity uptake of [3H] choline and the synthesis of [3H] acetylcholine. This lipid-induced inhibition was apparently competitive, since it was observed at 1 microM but not 20 microM extracellular concentration of choline. These results indicate that dipalmitoylphosphatidylcholine may reduce the synthesis of acetylcholine in resting nerve terminals.     

Structure of cerebral arterioles in cystathionine beta-synthase-deficient mice

We examined effects of hyperhomocysteinemia on structure and mechanics of cerebral arterioles. We measured plasma total homocysteine (tHcy) and pressure, diameter, and cross-sectional area of the vessel wall in maximally dilated cerebral arterioles in heterozygous cystathionine beta-synthase-deficient (CBS(+/-)) mice and wild-type (CBS(+/+)) littermates that were provided with drinking water that was unsupplemented (control diet) or supplemented with 0.5% L-methionine (high-methionine diet). Plasma tHcy was 5.0+/-1.1 micro mol/L in CBS(+/+) mice and 8.3+/-0.9 micro mol/L in CBS(+/-) mice (P<0.05 versus CBS(+/+) mice) fed the control diet. Plasma tHcy was 17.2+/-4.6 micro mol/L in CBS(+/+) mice and 21.2+/-3.9 micro mol/L in CBS(+/-) mice (P<0.05) fed the high-methionine diet. Cross-sectional area of the vessel wall was significantly increased in CBS(+/-) (437+/-22 micro m(2)) mice fed control diet and CBS(+/+) (442+/-36 micro m(2)) and CBS(+/-) (471+/-46 micro m(2)) mice fed high-methionine diet relative to CBS(+/+) (324+/-18 micro m(2)) mice fed control diet (P<0.05). During maximal dilatation, the stress-strain curves in cerebral arterioles of CBS(+/-) mice on control diet and CBS(+/+) and CBS(+/-) mice on high-methionine diet were shifted to the right of the curve in cerebral arterioles of CBS(+/+) mice on control diet, an indication that distensibility of cerebral arterioles was increased in mice with elevated levels of plasma tHcy. Thus, hyperhomocysteinemia in mice was associated with hypertrophy and an increase in distensibility of cerebral arterioles. These findings suggest that hyperhomocysteinemia promotes cerebral vascular hypertrophy and altered cerebral vascular mechanics, both of which may contribute to the increased incidence of stroke associated with hyperhomocysteinemia.     

From microbiota toward gastro-enteropancreatic neuroendocrine neoplasms: Are we on the highway to hell?

Gut microbiota is represented by different microorganisms that colonize the intestinal tract, mostly the large intestine, such as bacteria, fungi, archaea and viruses. The gut microbial balance has a key role in several functions. It modulates the host’s metabolism, maintains the gut barrier integrity, participates in the xenobiotics and drug metabolism, and acts as protection against gastro-intestinal pathogens through the host’s immune system modulation. The impaired gut microbiota, called dysbiosis, may be the result of an imbalance in this equilibrium and is linked with different diseases, including cancer. While most of the studies have focused on the association between microbiota and gastrointestinal adenocarcinomas, very little is known about gastroenteropancreatic (GEP) neuroendocrine neoplasms (NENs). In this review, we provide an overview concerning the complex interplay between gut microbiota and GEP NENs, focusing on the potential role in tumorigenesis and progression in these tumors.

     

One-Carbon Metabolism in Alzheimer’s Disease and Parkinson’s Disease Brain Tissue

Disruptions in one-carbon metabolism and elevated homocysteine have been previously implicated in the development of dementia associated with Alzheimer’s disease (AD) and Parkinson’s disease (PD). Moreover, a PD diagnosis itself carries substantial risk for the development of dementia. This is the first study that explores alterations in one-carbon metabolism in AD and PD directly in the human brain frontal cortex, the primary center of cognition. Applying targeted liquid chromatography–tandem mass spectrometry (LC-MS/MS), we analyzed post-mortem samples obtained from 136 subjects (35 AD, 65 PD, 36 controls). We found changes in one-carbon metabolites that indicate inefficient activation of cystathionine β-synthase (CBS) in AD and PD subjects with dementia, the latter seemingly accompanied by a restricted re-methylation flow. Levodopa–carbidopa is known to reduce available vitamin B6, which would explain the hindered CBS activity. We present evidence of temporary non-protein-bound homocysteine accumulation upon levodopa intake in the brain of PD subjects with dementia but not in non-demented PD subjects. Importantly, this homocysteine elevation is not related to levodopa dosage, disease progression, or histopathological markers but exclusively to the dementia status. We hypothesize that this levodopa-induced effect is a direct cause of dementia in PD in susceptible subjects with reduced re-methylation capacity. Furthermore, we show that betaine best correlates with cognitive score even among PD subjects alone and discuss nutritional recommendations to improve one-carbon metabolism function.     

Plasma homocysteine levels and folate status in children with sickle cell anemia.

PURPOSE: A sensitive inverse relationship between plasma homocysteine concentration and folate status has been demonstrated. Although children with sickle cell anemia (SCA) are at potential risk for folate deficiency, plasma homocysteine levels have not been reported in such patients. Therefore, a study was designed to assess plasma homocysteine levels as a marker of folate status. DESIGN: Plasma homocysteine concentrations were measured in 120 children with SCA (102 in steady state and 18 during an acute complication) who had never received supplemental folic acid. Folate status was directly assessed in 34 of these patients. RESULTS: Plasma homocysteine levels in the patients with SCA and control subjects were similar. The mean value +/- 1 SD was 5.8+/-2.5 micromol/L (range, 1.6 to 14.1 micromol/L) in the patients with SCA and 6.1+/-2.7 micromol/L (range, 1.7 to 15.3 micromol/L) in 73 pediatric control subjects. In a subpopulation of the study group (34 children), simultaneous serum folate, red cell folate, and total homocysteine concentrations were also measured. Their serum folate and red cell folate concentrations were normal: 12.4+/-10.0 nmol/L (range, 1 to 42 nmol/L) and 604+/-374.7 nmol/L (range, 205 to 1741 nmol/L), respectively. There was no correlation of plasma homocysteine concentration with various clinical or laboratory measures or with red cell folate concentration. CONCLUSION: Folate stores in children with SCA not receiving folic acid supplements are adequate despite an underlying hemolytic anemia.     

Homocysteine levels in preterm infants: is there an association with intraventricular hemorrhage? a prospective cohort study

Background  

The purpose of this study was to characterize total homocysteine (tHcy) levels at birth in preterm and term infants and identify associations with intraventricular hemorrhage (IVH) and other neonatal outcomes such as mortality, sepsis, necrotizing enterocolitis, bronchopulmonary dysplasia, and thrombocytopenia.     

Elevated S-adenosylhomocysteine in Alzheimer brain: influence on methyltransferases and cognitive function

Summary. Hyperhomocysteinemia is common in Alzheimers disease and is negatively correlated with cognitive function. Hyperhomocysteinemia can increase S-adenosylhomocysteine (SAH), a potent methyltransferase inhibitor. This study investigates the role of brain SAH in the cognitive and neurological disruption in Alzheimers disease. SAH was significantly (26%) higher in prefrontal cortex of Alzheimer patients than normals. Brain homogenates from Alzheimer patients inhibited an exogenous methyltransferase 15% more than normal homogenates (P<.001). Brain SAH levels correlated (r=.508) with methyltransferase inhibition by brain homogenates. Methyltransferase inhibition by Alzheimer brain homogenates correlated inversely with cognitive function as determined by MMSE (r=–0.36). Phenylethanolamine N-methyltransferase (PNMT) and catechol O-methyltransferase (COMT) activities were more than 30% lower (P<0.001) in Alzheimer than normal brains. Brain PNMT activity correlated significantly with cognitive function (r=0.243), age of Alzheimers onset (r=0.272), and choline acetyltransferase activity (r=0.333), but negatively with neurofibrillary tangles (r=–0.332). COMT activity also correlated significantly with cognitive function (r=0.324), age of disease onset (r=0.209), choline acetyltransferase activity (r=0.326), levels of synaptophysin (r=0.506), and negatively with tangles (r=–0.216 P=0.039). Elevated SAH in Alzheimer brain inhibits methyltransferases and is related to markers of disease progression and cognitive impairment.