Postmortem brain fatty acid profile of levodopa-treated Parkinson disease patients and parkinsonian monkeys

Fatty acids play a critical role in brain function but their specific role in the pathophysiology of Parkinson disease (PD) and levodopa-induced motor complications is still unknown. From a therapeutic standpoint, it is important to determine the relation between brain fatty acids and PD because the brain fatty acid content depends on nutritional intake, a readily manipulable environmental factor. Here, we report a postmortem analysis of fatty acid profile by gas chromatography in the brain cortex of human patients (12 PD patients and nine Controls) as well as in the brain cortex of monkeys (four controls, five drug-naive MPTP monkeys and seven levodopa-treated MPTP monkeys). Brain fatty acid profile of cerebral cortex tissue was similar between PD patients and Controls and was not correlated with age of death, delay to autopsy or brain pH. Levodopa administration in MPTP monkeys increased arachidonic acid content (+7%; P < 0 .05) but decreased docosahexaenoic acid concentration (-15%; P < 0.05) and total n-3:n-6 polyunsaturated fatty acids ratio (-27%; P < 0.01) compared to drug-naive MPTP animals. Interestingly, PD patients who experienced motor complications to levodopa had higher arachidonic acid concentrations in the cortex compared to Controls (+13.6%; P < 0.05) and to levodopa-treated PD patients devoid of motor complications (+14.4%; P < 0.05). Furthermore, PD patients who took an above-median cumulative dose of levodopa had a higher relative amount of saturated fatty acids but lower monounsaturated fatty acids in their brain cortex (P < 0.01). These results suggest that changes in brain fatty acid relative concentrations are associated with levodopa treatment in PD patients and in a non-human primate model of parkinsonism.

Genetic associations between cathepsin D exon 2 C-->T polymorphism and Alzheimer's disease, and pathological correlations with genotype

Genetic variations represent major risk factors for Alzheimer's disease (AD). While familial early onset AD is associated with mutations in the amyloid precursor protein and presenilin genes, only the e4 allele of the apolipoprotein E (APOE) gene has so far been established as a genetic risk factor for late onset familial and sporadic AD. It has been suggested that the C-->T (224Ala-->Val) transition within exon 2 of the cathepsin D gene (CTSD) might represent a risk factor for late onset AD. The objective of this study was to investigate whether possession of the CTSD exon 2 T allele increases the risk of developing AD, and to determine whether this modulates the amyloid pathology of the disease in conjunction with, or independent of, the APOE e4 allele. Blood samples were obtained from 412 patients with possible or probable AD and brain tissues from a further 148 patients with AD confirmed by postmortem examination. CTSD and APOE genotyping were performed by PCR on DNA extracted from blood, or from frontal cortex or cerebellum in the postmortem cases. Pathological measures of amyloid beta protein (Abeta), as plaque Abeta40 and Abeta42(3) load and degree of cerebral amyloid angiopathy were made by image analysis or semiquantitative rating, respectively. CTSD genotype frequencies in AD were not significantly different from those in control subjects, nor did these differ between cases of early or late onset AD or between younger and older controls. There was no gene interaction between the CTSD T and APOE e4 alleles. The amount of plaque Abeta40 was greater in patients carrying the CTSD T allele than in non-carriers, and in patients bearing APOE e4 allele compared with non-carriers. Possession of both these alleles acted synergistically to increase levels of plaque Abeta40, especially in those individuals who were homozygous for the APOE e4 allele. Possession of the CTSD T allele had no effect on plaque Abeta42(3) load or degree of CAA. Possession of the CTSD T allele does not increase the risk of developing AD per se, but has a modulating effect on the pathogenesis of the disorder by increasing, in concert with the APOE e4 allele, the amount of Abeta deposited as senile plaques in the brain in the form of Abeta40.

Leptin secretion after a high-fat meal in normal-weight rats: strong predictor of long-term body fat accrual on a high-fat diet

The objective of this study was to investigate meal-related endocrine changes that permit one to identify Sprague-Dawley rats at normal weight that are prone (OP) vs. resistant (OR) to obesity. In blood collected via chronic cardiac catheters, a 2-h high-fat meal (HFM, 50% fat, 40 kcal) at dark onset caused a significant increase in leptin, insulin, and triglycerides compared with premeal levels. Similar to patterns in already obese compared with lean rats on a high-fat diet, these meal-induced endocrine changes in normal-weight rats on lab chow were almost twofold larger in OP rats that, compared with OR rats, subsequently accumulated 100% more fat mass on a chronic high-fat diet. These exaggerated endocrine changes were similarly observed in blood collected using a simpler tail vein puncture procedure. In three separate experiments, the HFM-induced rise in leptin was found to be the strongest, positive correlate (r = +0.58, +0.62 and +0.64) of long-term body fat accrual. The lowest (2-5 ng/ml) vs. highest (6-9 ng/ml) scores for this post-HFM leptin measurement identified distinct OR and OP subgroups, respectively, when they were similar in body weight (340-350 g), premeal leptin (2.6-3.4 ng/ml), and meal size (40 kcal). Subsequent tests in these normal-weight OP rats revealed a distinct characteristic compared with OR rats, namely, exaggerated HFM-induced rise in expression of the orexigenic peptide galanin in the paraventricular nucleus. Thus, with this HFM-induced leptin measurement, OP rats can be identified while still at normal weight and then investigated for mechanisms that contribute to their excessive body fat accrual on a high-fat diet.

The apolipoprotein E epsilon4 allele selectively increases the risk of frontotemporal lobar degeneration in males

OBJECTIVE

To determine whether polymorphic variations in the apolipoprotein E gene (APOE) are associated with increased risk of frontotemporal lobar degeneration (FTLD) when mutation in tau gene is absent.

METHODS

The APOE gene was genotyped by polymerase chain reaction from DNA routinely extracted from blood or brain tissues. The APOE epsilon4 allele frequency in 198 patients with FTLD not associated with mutations in tau gene was compared with that of a control group of 756 normal individuals drawn from the same geographical region. Analyses were done according to clinical subtype or sex.

RESULTS

The APOE epsilon4 allele frequency (19.4%) was increased (p = 0.01) in FTLD v the whole control group (14.1%), while the APOE epsilon2 allele frequency in FTLD (6.5%) was slightly lower than in controls (8.0%) (NS). The APOE epsilon4 allele frequency in men with FTLD (22.3%) was greater (p = 0.002) than in male controls (12.3%); the frequency in women (16.3%) was similar to that in female controls (14.8%) (NS). The APOE epsilon2 allele frequency in men with FTLD was 4.9% while in male controls it was 9.5% (p = 0.06), but there was no difference in women (7.5% v 7.9%, NS). Neither the APOE epsilon2 nor APOE epsilon4 allele frequency varied significantly between any of the clinical subtypes.

CONCLUSIONS

In FTLD not associated with mutations in tau gene, possession of APOE epsilon4 allele in men roughly doubles the chances of developing disease, whereas this has no impact upon disease risk in women.

Single Molecule Study of Perylene Orange Photobleaching in Thin Sol−Gel Films

The paper reports on photobleaching mechanisms of perylene orange embedded in thin sol-gel films, derived from single molecule studies. The experimental configuration uses wide-field illumination and one photon excitation of the molecules. Measurements have been performed both at ambient conditions and under vacuum in order to get information on the influence of oxygen on photobleaching in such porous samples. We have also recorded the evolution of photobleaching with respect to the excitation intensity. The results demonstrate that photobleaching from excited states higher than the first singlet and triplet states has a nonnegligible contribution as soon as the excitation energy exceeds a few hundred W/cm2 and that this process is favored in the presence of air. The study also demonstrates that perylene orange in sol-gel films is not a very efficient emitter but that photobleaching can be slow, which explains the interest for perylene orange as a good candidate to produce long lifetime solid-state lasers when embedded in monoliths of sol-gel.

Different forms of obesity as a function of diet composition

OBJECTIVE

To characterize the phenotype of obesity on a high-carbohydrate diet (HCD) as compared to a high-fat diet (HFD) or moderate-fat diet (MFD).

METHODS AND PROCEDURES

In four experiments, adult Sprague-Dawley rats (275-300 g) were maintained for several weeks on a: (1) HFD with 50% fat; (2) balanced MFD with 25% fat; or (3) HCD with 10% fat/65% carbohydrate. Then, based on the amount of body fat accumulated in four dissected fat pads, the animals were subgrouped as lean (lowest tertile) or obese (highest tertile) and characterized with multiple measures.

RESULTS

The obese rats of these diet groups, with 70-80% greater body fat than the lean animals, exhibited elevated levels of leptin and insulin and increased activity of lipoprotein lipase in adipose tissue (aLPL), with no change in muscle LPL. Characteristics common to the obese rats on the HFD or MFD, but not seen on the HCD, were hyperphagia, elevated circulating levels of triglycerides (TG), nonesterified fatty acids (NEFA) and glucose, and a significant increase in beta-hydroxyacyl-CoA dehydrogenase (HADH) activity in muscle, reflecting its greater capacity to metabolize fat. This was accompanied by a significant increase in expression of the peptide, galanin (GAL), in the paraventricular nucleus (PVN), as measured by in situ hybridization and real-time quantitative PCR, and also in GAL peptide immunoreactivity. These measures of GAL were consistently, positively correlated with circulating TG levels and also with HADH activity in muscle. In contrast to these fat-associated changes, rats that became obese on an HCD maintained normal caloric intake and levels of TG, NEFA, and glucose. They also showed no change in PVN GAL mRNA or peptide. Instead, they exhibited a significant reduction in HADH activity compared to the lean animals, along with increased activity of phosphofructokinase in muscle, a key enzyme in glycolysis.

CONCLUSION

Specific characteristics of obesity, including expression of hypothalamic peptides, are dependent upon diet composition. Whereas obesity on an HFD is associated with hyperphagia and elevated lipids, fat metabolism in muscle, and fat-stimulated peptides such as GAL, obesity on an HCD with a similar increase in body fat shows none of these characteristics and instead exhibits a metabolic pattern in muscle that favors carbohydrate over fat oxidation. These results suggest the existence of multiple forms of obesity with different underlying mechanisms that are diet dependent.

[Pregnancy beyond age 40 in 382 women: a retrospective study in Reunion Island]

OBJECTIVE

To examine obstetrical and neonatal outcomes among women age 40 years and older.

MATERIAL AND METHODS

There was a retrospective study including 382 pregnant women at least 40 years of age and 7786 controls aged 20-34, stratified according to parity. Associations between maternal age and pregnancy outcomes were assessed using Pearson's chi(2) test, Fischer exact test, Student test or Mann and Whitney test, as appropriate.

RESULTS

Maternal age 40 and over was associated with an increased risk for gestational diabetes (multiparas: OR 3.2, 95%CI 2.2-4.8; grandmultiparas: 2.8, 1.6-5.0), chronic diabetes (multiparas: 3.5, 1.04-10.6), chronic hypertension (multiparas: 3.1, 1.5-6.1; grandmultiparas: 12.1, 3.3-53.2), pregnancy-induced hypertension (nulliparas: 4.6, 1.01-17.3; multiparas: 2.6, 1.3-5.4) and preclampsia (multiparas: 2.9, 1.1-7.2). The risk for cesarean section was 2-fold higher in older multiparas and grandmultiparas. The same was true for the rate of operative vaginal delivery. The rate of fetal chromosomal abnormalities was 7-fold higher in older gravidas. Rates of fetal death were significantly increased in the cohort of older pregnant women (nulliparas: 11.2, 2.9-44.0; multiparas: 3.9, 1.4-10.9).

CONCLUSION

Pregnancy at age 40 and over is associated with high rates of obstetrical complications, cesarean sections and operative vaginal deliveries, emphasizing the importance of rigorous antenatal care.

Assessment of vascular reactivity in rat brain glioma by measuring regional blood volume during graded hypoxic hypoxia

While morphological and molecular events during angiogenesis in brain glioma have been extensively studied, the functional properties of tumour vessels have yet received little attention. We have determined changes in regional blood volume (BV) during graded hypoxic hypoxia using susceptibility contrast magnetic resonance imaging in a model of rat brain glioma. Nine anaesthetised and ventilated rats with C6 glioma were subjected to incremental reduction in the fraction of inspired oxygen (FiO₂): 0.35, 0.25, 0.15, 0.12, 0.10 and reoxygenation to 0.35. At each episode, BV was determined in peritumoral, intratumoral and contralateral regions. Baseline BV values (FiO₂ of 0.35) were higher in peritumoral than in the contralateral and intratumoral regions. Progressive hypoxia resulted in a graded increase in BV in contralateral and peritumoral regions. At FiO₂ of 0.10, BV increases were comparable between these two regions: 49±22% (s.d.) and 28±17% with respect of control values, respectively. These BV changes reversed during the reoxygenation episode. By contrast, the intratumoral region had a significant increase in BV at FiO₂ of 0.10 only, with no evidence of return to the basal value during reoxygenation. Immunohistochemical staining of α-smooth muscle actin confirmed reactivity of vessels in the peritumoral region. Our findings indicate that peritumoral vessels present a vascular reactivity to hypoxia, which is comparable to that of nontumoral vessels. A method is thus available for noninvasively demonstrating whether any particular vascular modifying strategy results in the desired outcome in terms of tumour blood volume changes.

Vascular reactivity to norepinephrine and acetylcholine after chronic intermittent hypoxia in mice

This study assessed the early vascular reactivity changes in mice after exposure to 14 days intermittent hypoxia (IH) with active or inactive sympathetic nervous system (SNS). Hindquarters of mice exposed to 14 days of IH, sham exposed mice or unhandled mice were perfused at constant flow with Krebs-Albumin (5%). Changes in perfusion pressure were assessed after injection of several doses of norepinephrine in anaesthetized mice (active SNS) or in euthanized mice (inactive SNS). Response to several doses of acetylcholine was recorded after precontraction of hindquarter vascular bed by methoxamine in euthanized mice. Vasoconstrictor response was increased after IH for high dose of NE (50 microg) in euthanized mice and for all doses of NE (2-10-50 microg) in anaesthetized mice, but no change in vasodilatation was observed. These findings suggest that 14 days of IH altered vascular reactivity of mice hindquarter in an early pattern. Vasoconstriction was enhanced, particularly with active SNS, while there was no dysfunction of endothelium-relaxation.

Specific Raman signatures of a dimetallofullerene peapod

We report on the Raman spectroscopy of a dimetallofullerene peapod, (La(2)@C(80))(m)@SWNT. Drastic changes are observed with respect to pristine nanotubes. A sharp intense line at 142 cm(-1) is interpreted as a signature of polymerization of the encapsulated metallofullerenes. Additional strong signatures appear at about 400, 520, and 640 cm(-1), respectively. Their intensity suggests the existence of an enhancement effect. The stiffening and the up-shift of the G-band modes appear to imply that a charge transfer process between the nanotube and the peas occurs.

CAG/CTG repeat expansions at the Huntington's disease-like 2 locus are rare in Huntington's disease patients

The authors report a large series of patients with Huntington disease (HD)-like phenotype without CAG repeat expansions in the IT15 gene that were screened for the newly identified CAG/CTG expansion in the gene encoding junctophilin-3. Normal alleles in controls had from 8 to 28 repeats. A single patient of North African origin with typical HD carried an allele with 50 uninterrupted repeats, representing approximately 2% of the non-IT15 HD patients tested. Therefore, further genetic heterogeneity is expected in HD.

Frequency response of renal sympathetic nervous activity to aortic depressor nerve stimulation in the anaesthetized rat

1. The contribution of central baroreceptor reflex pathways to the dynamic regulation of sympathetic nervous activity (SNA) has not been properly examined thus far. The aim of this study was to characterize the transfer function of the central arc of the baroreceptor reflex (from baroreceptor afferent activity to SNA) over a wide range of frequencies. 2. In nine baroreceptor-intact and six sino-aortic baroreceptor-denervated rats anaesthetized with urethane, the renal SNA was recorded while applying sinusoidal stimulation to the aortic depressor nerve at 26 discrete frequencies ranging from 0.03 to 20 Hz. At each modulation frequency, cross-power spectrum analysis using a fast Fourier transform algorithm was performed between the stimulation and renal SNA, which provided the transfer function of the central arc. 3. In both baroreceptor intact and denervated rats, the transfer gain increased by a factor of about three between 0.03 and 1 Hz. At higher frequencies, the gain decreased but remained above the static gain of the system up to 12 Hz. There was a slight phase lead up to 0.4 Hz, then a continuously increasing phase lag. A three-element linear model satisfactorily described the experimental transfer function. The model combined a derivative gain (corner frequency approximately 0.15 Hz), an overdamped second-order low-pass filter (natural frequency approximately 1 Hz) and a fixed time delay (approximately 100 ms). 4. These results indicate that the central arc of the baroreceptor reflex shows derivative properties that are essential for compensating the filtering of fast oscillations of baroreceptor afferent activity and thus for the generation of fast oscillations of renal SNA (e.g. those related to the cardiac cycle).

Effect of alpha-adrenoceptor blockade on the 0.4 Hz sympathetic rhythm in conscious rats

1. The present study examined the origin of the 0.4 Hz rhythm in renal sympathetic nerve activity (RSNA) in rats. It was anticipated that, after elimination of 0.4 Hz oscillations of arterial pressure (AP) by alpha-adrenoceptor blockade, the persistence or disappearance of a 0.4 Hz rhythm in RSNA would point to an endogenous (central oscillator) or baroreflex origin, respectively. 2. Arterial pressure and RSNA were recorded in seven conscious rats, before and after acute alpha-adrenoceptor blockade with phentolamine (5 mg/kg, i.v.). In each condition, power and coherence spectra were calculated over 15 min periods of rest. 3. In control conditions, highly coherent AP and RSNA oscillations were observed near 0.4 Hz. After phentolamine administration, spectral power in the mid-frequency (0.27-0.74 Hz) band was significantly reduced for both AP and RSNA and maximum power was shifted towards 0.7 Hz. 4. The disappearance of the RSNA rhythm at 0.4 Hz after phentolamine administration favours the hypothesis of a baroreflex origin. The new oscillation near 0.7 Hz can derive either from the activity of a previously unrecognized central oscillator or from a faster feedback mechanism involving cotransmitters of noradrenaline acting with shorter time constants (e.g. ATP).

Sympathetic modulation of blood pressure variability

Although sympathetic nervous activity (SNA) displays oscillations synchronous with the heart beat and respiration, and between 0.1-0.4 Hz, it is apparent that each of these frequencies does not have the same effect on the vasculature. Frequencies above 1 Hz do not produce oscillations in the vasculature but instead contribute to the mean level of vasoconstriction. Slower oscillations in SNA result in a cycle of vasoconstriction and vasodilation within the vasculature, the amplitude of which, generally decreases with increasing frequency. Some studies indicate that, within the same species, differences exist in the frequency responses between vascular beds, such as the skin and gut. This differential responsiveness is also found between the medullary and cortical vasculature regions of the rabbit kidney. Low-pass filter properties have been described in the iliac circulation of rats, and evidence has been provided that noradrenaline reuptake mechanisms are not the frequency limiting step of the vasculature response. Recent studies on isolated rat vascular smooth muscle cells suggest that sympathetic modulation of vascular tone is limited by the alpha-adrenoceptor signal transduction into the cells and not by an intrinsic inability of the cells to contract and relax at higher rates.

[Autoregulation of renal blood flow and blood pressure variability in the conscious rat]

It is often proposed that autoregulatory mechanisms prevent acute changes in systemic blood pressure (BP) from being transmitted to the glomerular capillary circulation. However, it is not known whether renal blood flow (RBF) is still autoregulated when the kidney is exposed to exaggerated BP fluctuations, in particular hypertensive episodes. The aim of the present study was therefore to evaluate the efficacy of renal autoregulatory responses in an animal model of BP lability, the sinoaortic denervated (SAD) rat. BP and RBF were simultaneously recorded in 8 SAD (2 wks before study) and 8 baroreceptor intact (INT) Sprague-Dawley rats during approximately 3 h of spontaneous activity. The left kidney used for RBF recordings was denervated to prevent the interference of changes in renal sympathetic tone with autoregulatory responses. The SAD procedure modified neither the mean BP nor the mean RBF levels (111 +/- 1 mmHg and 11.3 +/- 1.3 mL/min in INT rats: 113 +/- 6 mmHg and 11.1 +/- 0.9 mL/min in SAD rats). However, SAD strongly increased the BP variability (coefficient of variation: 5.9 +/- 0.2% and 18.2 +/- 1.1% in INT and SAD rats, respectively). In spite of this marked BP lability, RBF variability was not significantly affected by the SAD procedure (9.1 +/- 0.8% and 12.4 +/- 1.6% in INT and SAD rats, respectively). In SAD rats, spontaneous hypertensive episodes (top 1% of BP values: 174 +/- 10 mmHg) did not induce increases in RBF (10.5 +/- 1.0 ml/min). Fast Fourier transform analysis revealed that in SAD rats, autoregulatory mechanisms attenuated approximately 80% of BP fluctuations in the 0.0015-0.01 Hz frequency range, suggesting a major involvement of the tubuloglomerular feedback. In conclusion, autoregulatory mechanisms have an ample capacity to protect the kidney against spontaneous BP fluctuations in the conscious rat. Consequently, BP variability per se is probably not detrimental to the kidney, as long as autoregulatory mechanisms are normally functioning.

Renal blood flow dynamics and arterial pressure lability in the conscious rat

It is not known whether renal blood flow (RBF) is still autoregulated when the kidney is exposed to large transient blood pressure (BP) fluctuations such as those occurring spontaneously in conscious sinoaortic baroreceptor-denervated (SAD) rats. In this study, BP and RBF were simultaneously recorded in 8 SAD rats (2 weeks before study) and 8 baroreceptor-intact rats during approximately 3 hours of spontaneous activity. The kidney used for RBF recordings was denervated to prevent the interference of changes in renal sympathetic tone with autoregulatory mechanisms. In intact rats, RBF variability (coefficient of variation 9.1+/-0.8%) was larger (P<0.02) than BP variability (5.9+/-0.2%). This was mainly because of slow changes in RBF that were unrelated to BP and also to a prominent oscillation of RBF of approximately 0.25-Hz frequency. Autoregulatory patterns were identified at frequencies <0.1 Hz and provided a modest attenuation of BP fluctuations. In SAD rats, RBF variability (12.4+/-1.6%) was lower (P<0.02) than BP variability (18.2+/-1.1%). Autoregulation powerfully attenuated BP changes <0.1 Hz (normalized transfer gain 0.21+/-0.02 in the 0.0015- to 0.01-Hz frequency range) but at the expense of an oscillation located at approximately 0.05 Hz that possibly reflected the operation of the tubuloglomerular feedback. Large transient hypertensive episodes were not translated into RBF changes in SAD rats. We conclude that autoregulatory mechanisms have an ample capacity to protect the kidney against spontaneous BP fluctuations in the conscious rat. This capacity is not fully used under normal conditions of low BP variability.

Vessel size imaging

Vessel size imaging is a new method that is based on simultaneous measurement of the changes Delta R(2) and Delta R(2)(*) in relaxation rate constants induced by the injection of an intravascular superparamagnetic contrast agent. Using the static dephasing approximation for Delta R(2)(*) estimation and the slow-diffusion approximation for Delta R(2) estimation, it is shown that the ratio Delta R(2)/Delta R(2)(*) can be expressed as a function of the susceptibility difference between vessels and brain tissue, the brain water diffusion coefficient, and a weighted mean of vessel sizes. Comparison of the results with 1) the Monte Carlo simulations used to quantify the relationship between tissue parameters and susceptibility contrast, 2) the experimental MRI data in the normal rat brain, and 3) the histologic data establishes the validity of this approach. This technique, which allows images of a weighted mean of the vessel size to be obtained, could be useful for in vivo studies of tumor vascularization. Magn Reson Med 45:397-408, 2001.