Functional phenotyping of successful aging in long‐term memory: Preserved performance in the absence of neural compensation

We investigated whether preservation of encoding‐related brain activity patterns in older age reflects successful aging in long‐term memory. Using a statistical matching technique, we identified groups of healthy older adults with different degrees of Functional Activity Deviation during Encoding (FADE) from young adults in a memory network comprising hippocampal, temporal, occipital, and retrosplenial regions. High FADE scores were associated with impairment in recollection, abnormal activity in the default mode network, and lower gray matter density in bilateral ventral prefrontal cortex and left rhinal cortex; a constellation previously associated with increased risk for dementia. Low FADE scores functionally phenotyped successful aging because recollection was well preserved and there was no evidence for compensatory prefrontal activation. Thus, for some individuals successful aging in long‐term memory reflects the preservation of a functionally specific memory network, and can occur in the absence of compensatory brain activity. ©2010 Wiley‐Liss, Inc.     

Himalomycin A and B: isolation and structure elucidation of new fridamycin type antibiotics from a marine Streptomyces isolate

In our screening of marine Streptomycetes for bioactive compounds, in addition to the known metabolites rabelomycin (1), fridamycin D (2b), N-benzylacetamide and N-(2'-phenylethyl)acetamide, two new anthracycline antibiotics designated as himalomycin A (2c) and B (2d) were isolated from the culture broth of the marine Streptomyces sp. isolate B6921. The structure of the new antibiotics was determined by comparison of the NMR data with those of fridamycin D (2b) and by detailed interpretation of mass, 1D and 2D NMR spectra.     

Acetaminophen-induced oxidant stress and cell injury in cultured mouse hepatocytes: protection by N-acetyl cysteine.

The increase in cellular and mitochondrial glutathione disulfide (GSSG) levels and the GSSG:GSH ratio after acetaminophen (AAP) overdose suggest the involvement of an oxidant stress in the pathophysiology. However, the initial severe depletion of hepatocellular glutathione makes quantitative assessment of the oxidant stress difficult. Therefore, we tested the hypothesis that oxidant stress precedes the onset of cell injury in a cell culture model using 2',7'-dichlorofluorescein (DCF) fluorescence as a marker for intracellular oxidant stress. Cultured primary murine hepatocytes were exposed to 5 mM AAP. DCF fluorescence, XTT reduction, lactate dehydrogenase (LDH) release, and trypan blue uptake were determined from 0 to 12 h. After glutathione depletion at 3 h, DCF fluorescence increased by 16-fold and was maintained at that level up to 12 h. At 1.5 h after AAP, a significant decrease of the cellular XTT reduction capacity was observed, which continued to decline until 9 h. Cell necrosis (LDH release, trypan blue uptake) was detectable in 20% of cells at 6 h, with a significant further increase at later time points. Pretreatment with 20 mM N-acetylcysteine (NAC) 1 h before AAP enhanced cellular glutathione content, prevented or attenuated the AAP-induced decrease of GSH levels and XTT reduction capacity, respectively, and reduced the loss of cell viability. Additionally, treatment with NAC 2 h after AAP exposure prevented further deterioration of XTT reduction at 3 h and later, and attenuated cell necrosis. Thus, AAP-induced oxidant stress precedes cell necrosis and, in cultured hepatocytes, the oxidant stress is involved in the propagation of cell injury.     

Biallelic inactivation of the SDHC gene in renal carcinoma associated with paraganglioma syndrome type 3

The etiology and pathogenesis of renal cell carcinoma (RCC) are only partially understood. Key findings in hereditary RCC, which may be site specific or a component of a syndrome, have contributed to our current understanding. Important heritable syndromes of RCC are those associated with pheochromocytoma, especially von Hippel-Lindau disease (VHL) associated with germline VHL mutations, and pheochromocytoma and paraganglioma syndrome (PGL) associated with mutations in one of the four genes (SDHA-D) encoding succinate dehydrogenase. A subset of individuals with SDHB and SDHD germline DNA mutations and variants develop RCC. RCC has never been described as a component of SDHC-associated PGL3. The European-American Pheochromocytoma and Paraganglioma Registry comprises 35 registrants with germline SDHC mutations. A new registrant had carotid body tumor (CBT) and his mother had CBT and bilateral RCC. Blood DNA, paragangliomas, and RCCs were analyzed for mutations and loss-of-heterozygosity (LOH) in/flanking SDHC and VHL. The proband with unilateral CBT had a germline SDHC c.3G>A (p.M1I) mutation. His mutation-positive mother had CBT at age 42, clear cell RCC (ccRCC) at age 68, and papillary RCC (pRCC) at age 69. Both paraganglial tumors showed somatic LOH of the SDHC locus. Both ccRCC and pRCC did not have a somatic SDHC mutation but showed LOH for intragenic and flanking markers of the SDHC locus. LOH was also present for the VHL locus. Our findings suggest that RCC is a component of PGL3. Biallelic inactivation of the SDHC gene may represent a new pathway of pathogenesis of syndromic and nonsyndromic RCC, perhaps of both clear cell and papillary histologies.     

ERP effects of methylphenidate and working memory load in healthy adults during a serial visual working memory task

The objective of the study was to investigate neuronal processing during the encoding, retention and retrieval phases of a serial visual working memory task. Particularly, we were interested in how these phases are affected by working memory load and how processing is modulated by methylphenidate. Healthy adults were asked to memorize the order of four, five or six pictures under methylphenidate (20 mg) and under placebo while brain electrical activity was recorded. On the performance level, the number of correct responses decreased with increasing working memory load. Concerning brain electrical activity, in the encoding phase P3 amplitudes increased at midline electrodes with increasing memory load while load had no effect in the retention and retrieval phase. Medication neither influenced performance nor the different processing stages significantly. Our data provide evidence that during the encoding phase more attentional resources are allocated in trials with higher load as reflected by larger P3 amplitudes.     

Synthesis of Vinylphosphonic Acid Anhydrides and their Copolymerization with Vinylphosphonic Acid

We present the synthesis and characterization of the compounds formed in a mixture of vinylphosphonic acid (VPA) and acetic anhydride used for the radical‐initiated VPA polymerization. High‐molecular‐weight PVPA with up to 109 000 g · mol⁻¹ was obtained from the polymerization of a mixture containing VPA, VPAAnh, VPADiAnh and their acetylated derivatives. Relative reactivities of these compounds were estimated. The resulting polymers were characterized by viscosimetry, light scattering and NMR measurements. The complexity of the polymer structure increases with increasing anhydride content in the reaction feed as can be concluded from the ¹H, ¹³C and ³¹P NMR spectra. This finding is in accordance with a cyclopolymerization mechanism resulting in five‐ and six‐membered anhydride rings within the polymer chain.

     

Three German fibrinogen Aα-chain amyloidosis patients with the p.Glu526Val mutation

Plasma protein fibrinogen variants cause fibrinogen A alpha-chain (AFib) amyloidosis, which presents with hypertension, proteinuria, and azotemia. Six AFib mutations have been reported thus far. We identified three patients who presented with marked proteinuria and serum creatinine elevations. Their kidney biopsies revealed destruction of the glomerular architecture by amyloid deposits with typical, apple-green birefringence in polarized light after Congo red staining. We found immunoreactivity against fibrinogen, which is typical for this type of amyloidosis. We sequenced the FGA exon 5 and demonstrated heterozygosity for the p.Glu526Val mutation in all three cases. This amino acid substitution is the most common fibrinogen A alpha-chain variant causing AFib amyloidosis. The mutation has been reported in individuals of European and American descent but not yet in German patients. AFib amyloidosis should therefore be considered an important differential diagnosis in German patients with renal amyloidosis. In the cases described here, the use of antibodies directed against fibrinogen, followed by direct gene sequencing, revealed the underlying cause.     

Development and validation of the quality of erection questionnaire

IntroductionThere are no psychometrically validated assessment tools designed to solely and specifically evaluate satisfaction with the quality of erections.AimTo develop and psychometrically analyze the Quality of Erection Questionnaire (QEQ), a new patient-reported measure developed to evaluate men’s satisfaction with the quality of their erections.MethodsThe questionnaire was developed through in-depth qualitative interviews of men with erectile dysfunction (ED) in the United States and Australia. An exploratory methodology study was conducted on 65 men with ED. Subsequently, the psychometric properties were confirmed in a larger dataset of 558 men with ED from two combined clinical trials.Main Outcome MeasuresIdentification of potential redundancy or outliers in items (Pearson inter-item correlations); exploratory factor analysis (unrotated and varimax rotated); internal consistency (Cronbach’s alpha); convergent validity (Pearson correlation coefficients between the QEQ total score and domain scores of the International Index of Erectile Function); known-groups validity (ability of the QEQ scores to differentiate between ED severity groups); test–retest reliability (Pearson correlation coefficient).ResultsThe QEQ demonstrated excellent convergent and known-groups validity. Additional analysis demonstrated high internal consistency (Cronbach’s alpha, 0.92). Item analysis demonstrated a unidimensional structure and suggested that satisfaction with hardness may be the key driver for satisfaction with overall quality of erections (r = 0.8). The smaller exploratory study demonstrated good test–retest reliability (r = 0.82).ConclusionsThe QEQ is a six-item, patient-reported measure with a unidimensional structure, which produces a total score that may be transformed to a 0–100 scale. Psychometric analysis confirmed reliability and validity of the QEQ, which solely and specifically evaluates satisfaction of men with the quality of their erections. The QEQ is a potentially useful measure for monitoring and evaluating treatment in those who are bothered by, or concerned about, their erectile function. Porst H, Gilbert C, Collins S, Huang X, Symonds T, Stecher V, and Hvidsten K. Development and validation of the Quality of Erection Questionnaire.     

Adenosine and kidney function

In this review we outline the unique effects of the autacoid adenosine in the kidney. Adenosine is present in the cytosol of renal cells and in the extracellular space of normoxic kidneys. Extracellular adenosine can derive from cellular adenosine release or extracellular breakdown of ATP, AMP, or cAMP. It is generated at enhanced rates when tubular NaCl reabsorption and thus transport work increase or when hypoxia is induced. Extracellular adenosine acts on adenosine receptor subtypes in the cell membranes to affect vascular and tubular functions. Adenosine lowers glomerular filtration rate (GFR) by constricting afferent arterioles, especially in superficial nephrons, and acts as a mediator of the tubuloglomerular feedback, i.e., a mechanism that coordinates GFR and tubular transport. In contrast, it leads to vasodilation in deep cortex and medulla. Moreover, adenosine tonically inhibits the renal release of renin and stimulates NaCl transport in the cortical proximal tubule but inhibits it in medullary segments including the medullary thick ascending limb. These differential effects of adenosine are subsequently analyzed in a more integrative way in the context of intrarenal metabolic regulation of kidney function, and potential pathophysiological consequences are outlined.