Rumination moderates the longitudinal associations of awareness of age-related change with depressive and anxiety symptoms

OBJECTIVE

Lower awareness of age-related gains (AARC-gains) and higher awareness of age-related losses (AARC-losses) may be risk factors for depressive and anxiety symptoms. We explored whether: (1) Baseline AARC-gains and AARC-losses predict depressive and anxiety symptoms at one-year follow-up; (2) age and rumination moderate these associations; (3) levels of AARC-gains and AARC-losses differ among individuals with different combinations of current and past depression and/or with different combinations of current and past anxiety.

METHODS

In this one-year longitudinal cohort study participants (N = 3386; mean age = 66.0; SD = 6.93) completed measures of AARC-gains, AARC-losses, rumination, depression, anxiety, and lifetime diagnosis of depression and anxiety in 2019 and 2020. Regression models with tests of interaction were used.

RESULTS

Higher AARC-losses, but not lower AARC-gains, predicted more depressive and anxiety symptoms. Age did not moderate these associations. Associations of lower AARC-gains and higher AARC-losses with more depressive symptoms and of higher AARC-losses with more anxiety symptoms were stronger in those with higher rumination. Individuals with both current and past depression reported highest AARC-losses and lowest AARC-gains. Those with current, but not past anxiety, reported highest AARC-losses.

CONCLUSION

Perceiving many age-related losses may place individuals at risk of depressive and anxiety symptoms, especially those who frequently ruminate.

Oral probiotics in the management of gingivitis in diabetic patients: a double blinded randomized controlled study

Diabetic patients are more prone to develop infections such as periodontal diseases. Bacteriotherapy with the concept of using good bacterial strains to replace the pathogenic ones emerged as a fascinating field due to the increasing incidence of antibiotic resistance. The aim of this study was to evaluate if a particular combination of probiotics (Lactobacillus Reuteri DSM 17938 and Lactobaciullus Reuteri ATCC PTA 5289) is useful in treating gingivitis in diabetic patients. Eighty adult patients with diagnosis of controlled diabetes type II and gingivitis were enrolled for this study and randomized in two groups. Only oral hygiene instructions were given. Bacteriotherapy (Lactobacillus Reuteri) was administered to test group. Outcome measures were presence of Plaque (P.I.) and Bleeding on Probing (B.O.P.). Data were collected at baseline and after 30 days. At 30 days, both groups showed a statistically significant clinical indexes reduction from baseline. More reduction was present in the test group for P.I. (14%±6) and for B.O.P. (18%±4) and was statistically significant (p less than 0.05). Within the limitations of this study, bacteriotherapy can be considered effective in reducing plaque and BOP in patients with controlled diabetes type II and gingivitis.

Effects of the application of high-pressure oxygen on the treatment of periodontal disease in diabetic patients

Purpose

In this study we wanted to observe the improvement in the healing of periodontal tissues in a group of diabetic patients treated with traditional methods compared to another group treated with the addition of oxygen.The potential of oxygen has long been known in the field of plastic surgery, where it is used to treat burns and skin lesions.

Materials and methods

This study consists in a split mouth study which involved 30 patients. We carefully treated them with periodontal therapy using manual and mechanical instrumentation. Then, we applied oxygen in half mouth according to randomization list. Finally we checked up patients after some weeks.

Results

Our results highlight that all areas treated with oxygen application healed more rapidly and better than no treated areas.

Conclusions

All in all, we have demonstrated that oxygen can improve the outcome of non-surgical periodontal treatment in diabetic subjects.

Effectiveness of two different desensitizing varnishes in reducing tooth sensitivity: a randomized double-blind clinical trial

PURPOSE

The aim of this study is to evaluate and compare the effectiveness of two different desensitizing varnishes.

MATERIALS AND METHODS

Ninety healthy adults suffering from tooth sensitivity were divided into three groups. Two different varnishes were used for the study: Fluor Protector S, containing 7700 ppm fluoride (group I), and Cervitec F, containing 1400 ppm fluoride and 0.3% chlorhexidine (group II). A placebo containing water and ethanol was applied for the third group. Tooth sensitivity was collected according the Schiff' scale at baseline and after 30 and 90 days.

RESULTS

Group I and group II improved with statistically significant results. Group III did not show any improvements.

CONCLUSIONS

Desensitizing varnishes are a valid treatment for tooth hypersensitivity.

Calcium transport and extracellular pH in epithelial membranes

Calcium plays a pivotal role in cell adhesion, ATPase function, and in membrane permeability. The molecular mechanism for these diverse actions include: hormonal factors, activation of intracellular mediators, and physical factors such as ionic mobility and pH. To further examine the effects of one physical factor, pH, we designed studies examining Ca transport in the isolated turtle bladder epithelium. This tissue is a high-resistance epithelium which reabsorbs Na and secretes H+. The turtle has only rudimentary parathyroid tissue, the gland does not respond to a lowered plasma Ca, and cyclic AMP is not a primary intracellular mediator. In a series of in vitro experiments, we examined Ca metabolism under conditions simulating metabolic acidosis and alkalosis. Acidosis markedly inhibited the mucosa-to-serosa Ca flux, while alkalosis stimulated it. The effect of acidosis on the mucosa-to-serosa Ca flux was independent of Na transport. Changing serosal pH had no effect on the serosa-to-mucosa Ca flux or on proton secretion. Total tissue Ca concentration, measured using atomic absorption spectrometry, was identical when the extracellular pH varied from 5.4 to 8.4. When epithelial cells were isolated and Ca uptake was measured over a wide pH range, a linear increase in uptake was seen as pH was increased from 4.4 to 8.4. In separated turtle bladder epithelial cells ATP-dependent Ca transport, in the mitochondrial-rich cells, was 4- to 5-fold higher than activity found in the granular cells. The mitochondrial-rich cells comprise approximately 20% of the total epithelial surface and are thought to be the cells primarily involved in proton secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of biofilm control in an elderly patient suffering from rheumatoid arthritis: a case report

The increase in the average age of the population forces dentists and dental hygienists to deal with clinical scenarios typical of the elderly. In old people deep changes present both in systemic and oral health. These changes affect the anatomical and functional integrity of many tissues, such as the mouth. Impairment of patients' oral hygiene becomes manifested by local infections and promotes the pathogenesis of periodontal diseases. There is also a significant increase in autoimmune diseases, which are defined as disorders of the immune system that result in abnormal immune responses. Among the autoimmune diseases of medical interest we report a case of rheumatoid arthritis (RA) strictly related to periodontal disease.

Is the risk of primary hyperparathyroidism increased in patients with untreated breast cancer?

BACKGROUND

An increased frequency of primary hyperparathyroidism (PHP) has been reported in patients with treated breast cancer (BC). PHP has been found in about 7% of BC patients after surgery and radio-, chemio- or hormonal therapy.

AIM

To evaluate the frequency of PHP in untreated BC patients.

SUBJECTS AND METHODS

We evaluated 186 women with BC and 233 women with thyroid cancer (TC, no.=122) or benign thyroid diseases (BTD, no.=111). In all patients, serum calcium, albumin, PTH, and 25-hydroxyvitamin D (25-OH vitD) were measured before any treatment.

RESULTS

Serum calcium concentrations were significantly higher in BC than in TC and BTD groups (median values 9.5 mg/dl, 9.3 mg/dl and 9.3 mg/dl, respectively) but, according to a logistic regression model, calcium was not significantly different between the 3 groups when age was taken into account. In all patients, serum calcium was in the normal range, indicating that no case of overt PHP was present. Five patients (1 in BC, 2 in TC, and 2 in BDT groups) had serum calcium close to the upper limit of normal range, high PTH and low 25-OH vitD, indicating a possible PHP with hypercalcemia masked by concomitant 25-OH vitD deficiency.

CONCLUSIONS

In untreated BC group, no patient had overt PHP and 1/186 (0.5%) presented a possible PHP masked by 25-OH vitD deficiency, a PHP frequency much lower than that observed in treated BC patients. These data suggest that the treatments of BC may be responsible for the increased frequency of PHP reported in previous studies.

Skeletal muscle differentiation: role of dehydroepiandrosterone sulfate

Dehydroepiandrosterone (DHEA) and its sulfonated form dehydroepiandrosterone sulfate (DHEAS) are the main circulating steroid hormones and many epidemiological studies show an inverse relationship between DHEA/DHEAS levels and muscle loss for which the primary cause is the accelerated protein breakdown. The aim of this work was to determine whether DHEA/DHEAS supplementation in differentiating C2C12 skeletal muscle cells might influence the expression of the atrophy-related ubiquitin ligase, MuRF-1, and thereby impact key molecules of the differentiation program. DHEA is the prohormone crucial for sex steroid synthesis, and DHEAS is thought to be its reservoir. However, our preliminary experiments showed that DHEAS, but not DHEA, is able to influence MuRF-1 expression. Therefore, we treated differentiating C2C12 cells with various concentrations of DHEAS and analyzed the expression of MuRF-1, Hsp70, myosin heavy chain (MHC), myogenin, and the activity of creatine kinase. We observed that DHEAS at physiological concentrations downregulates MuRF-1 expression and affects muscle differentiation, as shown by the increased levels of MHC, which is a sarcomeric protein that undergoes MuRF-1-dependent degradation, and also by an increase in creatine kinase activity and myogenin expression, which are two other well-known markers of differentiation. Moreover, we found that DHEAS might have a protective effect on differentiating cells as suggested by the augmented levels of Hsp70, a member of heat shock proteins family that, besides its cytoprotective action, seems to have a regulatory role on key atrophy genes such as MuRF-1. In conclusion, our data shed light on the role of DHEAS at physiologic concentrations in maintaining muscle mass.

Terrestrial gamma-ray flashes as powerful particle accelerators

Strong electric discharges associated with thunderstorms can produce terrestrial gamma-ray flashes (TGFs), i.e., intense bursts of x rays and γ rays lasting a few milliseconds or less. We present in this Letter new TGF timing and spectral data based on the observations of the Italian Space Agency AGILE satellite. We determine that the TGF emission above 10 MeV has a significant power-law spectral component reaching energies up to 100 MeV. These results challenge TGF theoretical models based on runaway electron acceleration. The TGF discharge electric field accelerates particles over the large distances for which maximal voltages of hundreds of megavolts can be established. The combination of huge potentials and large electric fields in TGFs can efficiently accelerate particles in large numbers, and we reconsider here the photon spectrum and the neutron production by photonuclear reactions in the atmosphere.

Gamma-ray localization of terrestrial gamma-ray flashes

Terrestrial gamma-ray flashes (TGFs) are very short bursts of high-energy photons and electrons originating in Earth's atmosphere. We present here a localization study of TGFs carried out at gamma-ray energies above 20 MeV based on an innovative event selection method. We use the AGILE satellite Silicon Tracker data that for the first time have been correlated with TGFs detected by the AGILE Mini-Calorimeter. We detect 8 TGFs with gamma-ray photons of energies above 20 MeV localized by the AGILE gamma-ray imager with an accuracy of ∼5-10° at 50 MeV. Remarkably, all TGF-associated gamma rays are compatible with a terrestrial production site closer to the subsatellite point than 400 km. Considering that our gamma rays reach the AGILE satellite at 540 km altitude with limited scattering or attenuation, our measurements provide the first precise direct localization of TGFs from space.

The SHOX region and its mutations

The short stature homeobox-containing (SHOX) gene lies in the pseudoautosomal region 1 (PAR1) that comprises 2.6 Mb of the short-arm tips of both the X and Y chromosomes. It is known that its heterozygous mutations cause Leri-Weill dyschondrosteosis (LWD) (OMIM #127300), while its homozygous mutations cause a severe form of dwarfism known as Langer mesomelic dysplasia (LMD) (OMIM #249700). The analysis of 238 LWD patients between 1998 and 2007 by multiple authors shows a prevalence of deletions (46.4%) compared to point mutations (21.2%). On the whole, deletions and point mutations account for about 67% of LWD patients. SHOX is located within a 1000 kb desert region without genes. The comparative genomic analysis of this region between genomes of different vertebrates has led to the identification of evolutionarily conserved non-coding DNA elements (CNE). Further functional studies have shown that one of these CNE downstream of the SHOX gene is necessary for the expression of SHOX; this is considered to be typical "enhancer" activity. Including the enhancer, the overall mutation of the SHOX region in LWD patients does not hold in 100% of cases. Various authors have demonstrated the existence of other CNE both downstream and upstream of SHOX regions. The resulting conclusion is that it is necessary to reanalyze all LWD/LMD patients without SHOX mutations for the presence of mutations in the 5'- and 3'-flanking SHOX regions.

Effects of chronic Rhodiola Rosea supplementation on sport performance and antioxidant capacity in trained male: preliminary results

AIM

Rhodiola Rosea, is an adaptogen plant which has been reported to promote fatty acids utilisation, to ameliorate antioxidant function, and to improve body resistance to physical strenuous efforts. The purpose of the present study was to investigate the effects on physical performance as well as on the redox status of a chronic Rhodiola Rosea supplementation in a group of competitive athletes during endurance exercise.

METHODS

Following a chronic supplementation with Rhodiola Rosea for 4 weeks, 14 trained male athletes underwent a cardio-pulmonary exhaustion test and blood samples to evaluate their antioxidant status and other biochemical parameters. These data were compared with those coming from the same athletes after an intake of placebo.

RESULTS

The evaluation of physical performance parameters showed that HR Max, Borg Scale level, VO(2) max and duration of the test were essentially unaffected by Rhodiola Rosea assumption. On the contrary, Rhodiola Rosea intake reduced, in a statistically significative manner, plasma free fatty acids levels. No effect on blood glucose was found. Blood antioxidant status and inflammatory parameters resulted unaffected by Rhodiola Rosea supplementation. Blood lactate and plasma creatine kinase levels were found significantly lower (P<0.05) in Rhodiola Rosea treated subjects when compared to the placebo treated group.

CONCLUSION

Chronic Rhodiola Rosea supplementation is able to reduce both lactate levels and parameters of skeletal muscle damage after an exhaustive exercise session. Moreover this supplementation seems to ameliorate fatty acid consumption. Taken together those observation confirm that Rhodiola Rosea may increase the adaptogen ability to physical exercise.

A comparative study of adduct formation between the anticancer ruthenium(III) compound HInd trans-[RuCl4(Ind)2] and serum proteins

Formation of adducts between the antitumor ruthenium(III) complex [HInd]trans-[RuCl(4)(Ind)(2)] (KP1019) and the plasma proteins serum albumin and serum transferrin was investigated by UV-vis spectroscopy, for metal-to-protein ratios ranging from 1:1 to 5:1. In both cases, formation of tight metal-protein conjugates was observed. Similar spectroscopic features were observed for both albumin and transferrin derivatives implying a similar binding mode of the ruthenium species to these proteins. Surface histidines are the probable anchoring sites for the bound ruthenium(III) ions in line with previous crystallographic results. In order to assess the stability of the KP1019-protein adducts the influence of pH, reducing agents and chelators was analysed by UV-vis spectroscopy. Notably, there was no effect of addition of EDTA on the UV-vis spectra of the conjugates. The pH-stability was high in the pH range 5-8. Experiments with sodium ascorbate showed that there was just some alteration of selected bands. The implications of the present results are discussed in relation to the pharmacological behavior of this novel class of antitumor compounds.

The female athlete triad

The female athlete triad, a syndrome of disordered eating, amenorrhea, and osteoporosis, is now clearly recognized in selected populations of elite athletes. It is often seen in the sports that have an emphasis on "thinness," including gymnastics, figure skating, and ballet. Components of the triad are linked pathophysiologically, leading to significant morbidity and, on occasion, mortality. The disorder is difficult to treat and requires a multidisciplinary approach with intense psychological counseling as the primary focus of attack.

Reaction mechanism between nitric oxide and glutathione mediated by Fe(III) myoglobin

Ferrimyoglobin at pH 7.4 binds nitric oxide to yield nitric oxide adducts. In the presence of glutathione (GSH), nitrosoadducts of Mb(III) react with it to give nitrosoglutathione, whose concentration has been determined with an apparatus based on a specific and sensitive solid-state amperometric gas sensor. The reaction constant between the adduct and glutathione, kGSH = (47 +/- 1) M(-1) x s(-1), obtained by UV-Vis spectroscopy kinetic measurements, is about one-eighth of the constant with OH- determined by other authors. We can explain this fact with the higher nucleophilicity of OH- compared to GSH, due to the bulkiness and charge of the species. It is known that the formation of nitrosothiols starting from nitrite or NO (nitrogen monoxide) and glutathione, in the absence of oxygen, is impossible. Thus, from a biological point of view, it is important to point out that GSH reacts with NO in the presence of ferrimyoglobin, even at physiological pH, to form nitrosoglutathione.

Life-long food restriction prevents renal membrane lipid deposition and lowers renal work in rats

Renal cortical brush-border (BBM), basolateral membrane (BLM), and medullary plasma membrane (mPM) preparations were analyzed to assess the effects of life-long food restriction in aged rats on membrane lipid content. Young male Fischer 344 x Brown-Norway F1 rats consumed food ad libitum (young AL) or were food-restricted (FR, 60% of AL consumption) for either 6 weeks (young FR) or until the age of 30 months old (old FR). Senescent FR rats had 50 per cent decreases in fractional excretion of Na and K (p < 0.001) as compared with the young AL rats. Long-term FR reduced phosphate and titratable acid excretion by 80 per cent (p < 0.001). These values were not significantly different from those observed in young rats during 6 weeks of FR. Food restriction decreased renal Na, K-ATPase activity by 50 per cent (p < 0.001) in both old and young FR animals. Reduction of food intake, in old and young rats, decreased all BBM phospholipid concentrations (phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin) by 50 per cent than in the AL rats (p < 0.001). In BLM, chronic FR resulted only in lower phosphatidylcholine concentration (by 21%, p < 0.05) while phosphatidylethanolamine was increased approximately 80 per cent (p < 0.001). Total phospholipid content in mPM was progressively decreased by 23 per cent (p < 0.05) in the young FR group to be 55 per cent (p < 0.001) in the old FR rats. Cholesterol content was reduced in BBM and mPM by 38 per cent and 25 per cent (p < 0.05), respectively, during long-term FR. Both total phospholipid and cholesterol contents detected in mPM of the old FR rats were significantly lower than those obtained from the young FR animals (by 42%, p < 0.001 and 12%, p < 0.05, respectively). Plasma glucose, blood urea nitrogen, and body weight maintained at significantly lower levels during chronic FR. That life-long FR could prevent renal membrane lipid deposition and could lower renal work may explain the mechanisms that FR can delay the onset and diminish the severity of age-associated renal diseases.

Induction of gene expression via activator protein-1 in the ascorbate protection against UV-induced damage

UV irradiation is a major insult to the skin. We have shown previously that exogenous vitamin C (ascorbate) accumulates in HaCaT keratinocytes, thus conferring the ability to prevent radical formation and cell death elicited by UV-B. Here, we have investigated the potential mechanisms accounting for the cytoprotective effects exerted by this antioxidant. Using a cDNA microarray hybridization, we identified several genes whose expression was up-regulated by ascorbate. We focused on the fra-1 gene, a member of the Fos family of transcription factors that down-regulates activator protein-1 (AP-1) target genes. Both in HaCaT and in normal human epidermal keratinocytes, we found Fra-1 mRNA induction as early as 2 h after ascorbate loading. Electrophoretic mobility-shift assay and antibody supershift analysis revealed that ascorbate modulates AP-1 DNA-binding activity and that Fra-1 is in AP-1 complexes in treated cells. Furthermore, transient-transfection studies, using an AP-1 reporter construct, showed that ascorbate was able to inhibit both basal and UV-B-induced AP-1-dependent transcription. Ascorbate also modulates UV-B-induced AP-1 activity by preventing the phosphorylation and activation of the upstream c-Jun N-terminal kinase (JNK), thus inhibiting phosphorylation of the endogenous c-Jun protein. These data suggest that ascorbate mediates cellular responses aimed at counteracting UV-mediated cell damage and cell death by interfering at multiple levels with the activity of the JNK/AP-1 pathway and modulating the expression of AP-1-regulated genes.

Hormonal insights into the pathogenesis of cyclic idiopathic edema

Cyclic idiopathic edema is a nonlife-threatening syndrome of excessive weight gain. Although the cause is not clear, a number of hormones are postulated to be involved. Altered vascular permeability and increased lymph formation may also be part of the disorder. This article reviews some relevant data as to the pathogenesis of this noninflammatory disorder, concluding with an approach to diagnosis and therapy.

Biochemical and genetic advances in distal renal tubular acidosis

Distal renal tubular acidosis is a constellation of syndromes arising from different derangements of tubular acid transport. Recent advances in the biology of urinary acidification have allowed us to discern various molecular mechanisms responsible for these syndromes. This article relates clinical disorders of distal acidification to the underlying defective mechanisms responsible for them. A clinical classification of these disorders is presented which integrates each disorder with the prevailing serum potassium concentration. That distal renal tubular acidosis can be associated with low, normal, or high serum potassium concentration is now explainable by identifying the specific defect in transport causing each syndrome.

Activation of different lipoxygenase isozymes induces apoptosis in human erythroleukemia and neuroblastoma cells

We investigated the ability of different hydroperoxides generated by lipoxygenase isozymes to induce programmed cell death (PCD) in human cells. Erythroleukemia K562 and neuroblastoma CHP100 cells were used, because they showed high basal activity of lipoxygenase. The hydroperoxides generated by 5-, 12-, or 15-lipoxygenases from linoleate, linolenate, or arachidonate, and the corresponding hydroxides, were able to induce PCD in both cell types, in a concentration- and time-dependent manner. After 24 h, K562 and CHP100 cells showed 2.5- to 3.5-fold more apoptotic bodies than the untreated controls. PCD elicited by lipoxygenase products was independent of intracellular glutathione concentration, and did not require mRNA transcription or protein synthesis. On the other hand, lipoxygenase products evoked an immediate and sustained rise in cytoplasmic calcium (within seconds), followed by mitochondrial uncoupling (within hours). Unlike the hydro(pero)xides, the terminal products of the arachidonate cascade (i.e., leukotrienes, prostaglandins and thromboxane) were not cytotoxic.

Nitric oxide inhibits apoptosis via AP-1-dependent CD95L transactivation

Several inducers of cytotoxic stress promote apoptotic cell death, which, at least in some cases, involves the CD95/CD95 ligand (CD95L) pathway. The induction of the CD95/CD95L pathway can be activated by the activator protein-1 (AP-1)-mediated up-regulation of the CD95L promoter, which is responsible for the induction of apoptosis elicited by stimuli such as etoposide. We show that nitric oxide (NO) represents a regulatory element able to block apoptosis by interfering with this loop. Etoposide- and C6-ceramide-induced apoptosis in Jurkat T cells with different kinetics. Cell death was accompanied by an increase in DNA-binding activity of the transcription factor AP-1, transactivation of the AP-1 site-containing CD95L promoter, and caspase 3-like protease activation. Using different NO-releasing compounds, we found that apoptosis was prevented in a dose-dependent manner. Furthermore, in both models of apoptosis, NO-releasing compounds dose-dependently reduced: (a) the number of the titratable thiol groups (cysteine residues) of c-Jun; (b) induction of AP-1 DNA-binding activity; (c) AP-1-driven transactivation of the CD95L promoter; and (d) caspase activation. In conclusion, our data demonstrate that NO can modulate cell death at an upstream level, by interfering with the ability of AP-1 to induce CD95L expression.

Identification and disruption of an Arabidopsis zinc finger gene controlling seed germination

We describe here the Arabidopsis gene DAG1, encoding a zinc finger transcription factor of the Dof family, and show that it is involved in the control of seed germination. By a reverse genetics approach, we isolated an Arabidopsis mutant line with one T-DNA insertion in DAG1. Seeds from homozygous knockout dag1-1 plants do not develop dormancy and germinate also in the absence of light. Segregation analysis indicates that the effect of the mutation is maternal. Accordingly, in situ mRNA hybridizations reveal expression of DAG1 in the vascular tissue of the flower and maturing fruit but not in the seed.

An auxin-dependent distal organizer of pattern and polarity in the Arabidopsis root

Root formation in plants involves the continuous interpretation of positional cues. Physiological studies have linked root formation to auxins. An auxin response element displays a maximum in the Arabidopsis root and we investigate its developmental significance. Auxin response mutants reduce the maximum or its perception, and interfere with distal root patterning. Polar auxin transport mutants affect its localization and distal pattern. Polar auxin transport inhibitors cause dramatic relocalization of the maximum, and associated changes in pattern and polarity. Auxin application and laser ablations correlate root pattern with a maximum adjacent to the vascular bundle. Our data indicate that an auxin maximum at a vascular boundary establishes a distal organizer in the root.

Studies on 6-aminoquinolones: synthesis and antibacterial evaluation of 6-amino-8-ethyl- and 6-amino-8-methoxyquinolones

From our quantitative structure-activity relationship (QSAR) study on a large set of 6-aminoquinolones, which indicated that a group larger than methyl could be allocated at C-8 position, we have synthesized two new series of 6-aminoquinolones characterized by the presence of an ethyl or a methoxy group at C-8 position. The antibacterial evaluation shows that, while the 8-ethyl derivatives were devoid of any antibacterial activity, the introduction of methoxy group gave compounds with good antibacterial activity, especially against gram-positive bacteria. A tentative explanation of the different behaviours among the 8-substituted analogues is given taking into account both the length and electronic properties of the C-8 groups.

Age-related changes in renal function, membrane protein metabolism, and Na,K-ATPase activity and abundance in hypokalemic F344 x BNF(1) rats

BACKGROUND

Potassium depletion is a common electrolyte abnormality in elderly humans, usually as a consequence of diuretic use or poor oral intake. Hypokalemia is associated with a number of changes in renal function and an increase in some renal membrane transporters; its growth-promoting effect in young animals is well known. With aging, the renal adaptation to a number of challenges is often diminished. We hypothesized that aging is related to decreases in renal function, renal membrane protein metabolism, as well as Na, K-ATPase protein abundance and activity in both control animals as well as in those with potassium depletion.

OBJECTIVE

We examined the effects of dietary-induced hypokalemia in true-aged nonobese rats (30 months old) on renal function, cortical brush border membrane (BBM) and basolateral membrane (BLM) protein metabolism, and Na,K-ATPase protein abundance and activity. We compared the results obtained to those seen in their 4-month-old counterparts similarly treated.

METHODS

Young (4-month-old) and senescent (30-month-old) male Fisher 344 x Brown-Norway F(1) rats (F344 x BNF(1)) were fed either a normal or potassium-deficient diet for 7 days. At 24 h, the U-(14)C-leucine incorporation was measured for determination of protein metabolism in renal BBM and BLM. Cortical BLM vesicle and microdissected proximal convoluted tubule (PCT) Na, K-ATPase activities were determined along with Western blot analysis of the cortical BLM alpha(1) subunit of Na,K-ATPase. Metabolic and renal function parameters were also examined.

RESULTS

Hypokalemia caused hyperbicarbonatemia, hyperglycemia, and azotemia, but only in the senescent animals. The aged control rats had a higher basal level of urine volume, ammonium excretion, and fractional excretion of chloride. By contrast, aging in the F344 x BNF(1) rats was associated with a decrease in plasma aldosterone (by 35%) and phosphate (by 40%) levels as compared with their young controls. Hypokalemia resulted in a significant reduction of plasma aldosterone and a rise in muscle sodium concentration in both age groups; it significantly increased renal BBM and BLM protein concentrations in the young group, while these parameters remained unchanged in the senescent rats. The aged potassium-depleted animals showed a 14% decrease in BBM protein biosynthesis, but there were no changes in the young hypokalemic rats. Both potassium-depleted elderly and young rats had a significant reduction (by 33%) in BLM protein biosynthesis. Hypokalemia significantly increased the Na, K-ATPase activity in both cortical BLM vesicles and in microdissected PCT. The percentage increase in microdissected PCT segments (Na,K-ATPase activity) in elderly potassium-depleted animals was significantly less than that seen in hypokalemic young ones. Aging, per se, was associated with decreased basal microdissected PCT Na,K-ATPase activity in control animals. Hypokalemia had no effect on cortical BLM alpha(1) subunit Na, K-ATPase protein abundance in either age group.

CONCLUSIONS

The present study provides the first evidence in nonobese aged rats as to the metabolic parameters, renal function, renal cortical membrane protein metabolism, and transporter Na,K-ATPase activity and abundance during potassium depletion. The aged nonobese F344 x BNF(1) rats responded differently from their young nonobese counterparts following potassium depletion. These differences may contribute substantially to the effects often encountered in elderly humans receiving diuretics or having a poor dietary potassium intake.

Food restriction beneficially affects renal transport and cortical membrane lipid content in rats

Food restriction (FR) exerts a variety of beneficial effects and may prolong life in both humans and animals. However, studies of its effects on the cortical brush border membrane (BBM) and basolateral membrane (BLM) lipid concentration, which may be pertinent to renal function, have not been reported in detail. We hypothesized that FR would decrease renal work and lower renal membrane lipid concentration. The changes in lipid concentration would be most dramatic in BBM because this membrane is the entry site for the recovery of filtered ions and nutrients. Young male Fischer 344 x Brown-Norway F1 rats consumed food ad libitum (AL) or were food-restricted (FR, 60% of AL consumption) for 6 wk. AL rats had higher fractional excretions of Na(+), K(+), and Cl(-) than did the FR group (P < 0.001). Renal Na,K-ATPase activity in AL rats was 100% higher than in FR rats (P < 0.001), reflecting greater renal work. The work required for renal proton secretion was lower in FR than in the AL rats. In FR rats, all BBM phospholipid concentrations (phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin) were approximately 50% lower than in the AL rats (P < 0.001). In the BLM, food restriction resulted only in lower phosphatidylcholine concentration, while the other phospholipids were unaffected. Plasma and renal membrane (BBM and BLM) cholesterol concentrations were significantly lower in FR than in AL rats. These results show that a nutritionally complete, but energy restricted, diet improves renal function. It also prevents renal membrane lipid deposition and decreases plasma cholesterol. Prolonged food restriction might attenuate the renal injury that occurs in obese humans as a consequence of insulin resistance and atherosclerosis.

Potassium depletion: renal membrane lipid metabolism and Na/H exchanger abundance in aged F344 x BNF1 rats

Potassium depletion (-K) is a common electrolyte abnormality in elderly humans, occurring after diuretic use or poor oral intake. We hypothesized that aging would result in an increase in renal membrane lipid metabolism in both control and -K, and that the Na/H exchanger's protein abundance to -K would be blunted. Young and senescent non-obese male Fisher 344 x Brown-Norway F1 rats (F344 x BNF1) were fed either a normal or a K-deficient diet for 7 days. At 24-h, 32P incorporation was measured for renal cortical brush-border (BBM) and basolateral membrane (BLM) lipid metabolism. All -K animals showed a reduction in total body potassium stores, a fall in plasma aldosterone, a urinary concentrating defect, and an increase in plasma cholesterol and urine ammonium excretion (p < .001). In BBM of both age groups, -K increased phosphatidylserine, sphingomyelin, phosphatidylcholine, and phosphatidylethanolamine concentrations, but 32P incorporation fell. In BLM of young K-depleted rats, however, only phosphatidylcholine concentration increased. In the hypokalemic aged rats, the concentration of all BLM phospholipids rose, whereas 32P incorporation fell. In both membranes, cholesterol concentration and the molar ratio of cholesterol to total phospholipid increased with -K (p < .05). Potassium depletion caused brush-border membrane NHE-3 protein abundance to rise, but only in the young rats. Neither NHE-3 nor basolateral NHE-1 protein abundance was affected in aged animals with -K. These results provide the first evidence, in non-obese aged rats, that selective age-associated modifications occur in membrane lipid metabolism and membrane transporter protein abundance during -K. That aging causes a maladaptive response in brush-border NHE-3 protein expression may have important implications for elderly humans, particularly if they are given diuretics and become potassium depleted.

Role of calcium in the reaction between pyrroloquinoline quinone and pyridine nucleotides monomers and dimers

Redox reactions were carried out in aerobiosis and anaerobiosis between NAD(P) dimers or NAD(P)H and pyrroloquinoline quinone (PQQ) in different buffers. The buffer system and pH significantly affected the oxidation rates of nucleotides and the ESR signal intensity of the PQQ(*) radical formed in anaerobiosis by comproportion between the quinone and quinol forms. The relative reactivity of the four nucleotides toward PQQ was affected by pH and buffer nature. PQQ, which behaves as an electron shuttle from nucleotides to oxygen, was first converted to PQQH(2) and then rapidly reoxidized by oxygen, with formation of hydrogen peroxide. Both NAD(P) dimers and NAD(P)H consumed 1 mol of oxygen per mole of reacted molecule of pyridine nucleotide, yielding 1 or 2 mol of NAD(P)(+) from NAD(P)H or from NAD(P) dimers, respectively. Chelating agents such as EDTA and phytate strongly decreased the reaction rate and the PQQ(*) radical signal intensity. Kinetics carried out in the presence of metal ions showed instead an increased reaction rate in the order Ca(2+) >> Mg(2+) > Na(+) >> K(+). Spectrofluorimetric measurements of PQQ with increasing concentrations of Ca(2+) showed a fluorescence quenching and shift of the maximum emission toward lower wavelengths, while other metal ions showed minor effects, if any. Therefore, it is demonstrated that Ca(2+) binds to PQQ, probably forming a complex which is more reactive with both one-electron (NAD(P) dimers) or two-electron donors (NAD(P)H) in nonenzymic reactions. It is important to recall that Ca(2+) was already found to play active role in PQQ-containing enzymes.

Altered sodium pump alpha and gamma subunit gene expression in nephron segments from hypertensive rats

OBJECTIVE

To determine the qualitative and quantitative expression of alpha and gamma sodium pump subunits in whole kidney and nephron segment RNA from Sprague Dawley rats, spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats.

DESIGN

A novel reverse transcription polymerase chain reaction technique was devised which provides accurate and precise measurement of the number of molecules of specific transcript abundance, a measurement of gene expression. This allows the quantitative comparison of multiple samples across multiple subjects and, since the estimates are accurate rather than relative, can also be used to make quantitative comparisons across expressed genes, such as isoforms and subunits of the heterotrimeric renal sodium pump.

METHODS

We examined which catalytic isoforms were expressed and then quantified transcript abundance in whole kidney and convoluted and straight segments of the proximal tubule.

RESULTS

Alpha 1 and gamma transcripts, but not alpha 2, alpha 3 or alpha 4 isoforms, were consistently observed in nephron segments. Levels of alpha 1 were lower in kidney RNA from 15-16-week-old SHR than in WKY rats of the same age (P = 0.001), but were not different between SHR and WKY in 4-5-week-old animals. No significant difference was observed in gamma subunit abundance in kidney RNA from 4-5-week-old animals; however, at 15-16 weeks, the expression in SHR was one-third that in WKY rats (P = 0.003). In proximal convoluted tubules from 4-5-week-old animals, the level of alpha 1 RNA expression was lower (P = 0.03) in SHR than in WKY rats. In addition, levels of alpha 1 in proximal straight tubule from the 4-5-week-old SHR were also lower than in WKY rats (P = 0.02). This difference was even greater in 15-16-week-old animals: in SHR, alpha 1 expression was less than 20% of the level of expression in WKY rats (P = 0.0003). Expression of the gamma subunit exhibited a similar pattern of downregulation in SHR. In RNA from proximal convoluted tubules and proximal straight tubules from both 4-5- and 15-16-week-old animals, expression of the gamma subunit was demonstrated to be significantly lower in SHR than in WKY rats.

CONCLUSION

The results indicate a coordinate reduction in the abundance of sodium pump alpha and gamma subunits in the proximal tubules of SHR, which occurs early during the development of hypertension.

Design and synthesis of modified quinolones as antitumoral acridones

The bacterial topoisomerase II (DNA gyrase) and the mammalian topoisomerase II represent the cellular targets for quinolone antibacterials and a wide variety of anticancer drugs, respectively. In view of the mechanistic similarities and sequence homologies exhibited by the two enzymes, tentative efforts to selectively shift from an antibacterial to an antitumoral activity was made by synthesizing a series of modified tricyclic quinolones, in which the essential 3-carboxylic function is surrogated by phenolic OH and the classic C-6 fluorine atom is replaced by a NH2 group. The resulting 7-amino-9-acridone derivatives were assayed for their antibacterial as well as cytotoxic activities. No antibacterial activity was found. On the other hand, many derivatives showed significant cytotoxic activity against both HL-60 and P388 leukemias and a wide panel of human and rodent solid tumor cells, derivatives 25 and 26 displaying the best overall antiproliferative activity. Against the LoVo cell line, derivative 25 exhibited higher cytotoxic effects than etoposide.

Experimental studies in distal urinary acidification: bringing the bedside to the bench

The renal tubular acidosis syndromes are nonuremic defects of urinary acidification. They are characterized by a normal anion gap and hyperchloremic metabolic acidosis; plasma potassium may be normal, low, or high, depending on the syndrome present. As new technologies have been applied to biology, we now better understand the basic lesions of these important syndromes.

Drug substitution in transplantation: a National Kidney Foundation White Paper

Specific safeguards to guide the approval process and substitution practices for generic immunosuppressive agents are necessary for the effective delivery of patient care. Currently, the Food and Drug Administration (FDA) requires the demonstration of bioequivalence of generic drugs to innovator drugs in normal healthy subjects, a criterion that may be insufficient for critical-dose drugs. For generic equivalents of critical-dose drugs and for innovator critical-dose drugs, there should be a requirement for replicate studies measuring intrasubject variability and subject-treatment interactions to establish that bioequivalence holds true. Extensive testing of generic drugs in all target patient types is impractical and should not be required. However, when evidence suggests that the bioavailability of a critical-dose drug may vary substantially in certain subgroups, the FDA should require a demonstration of bioequivalence of generic versions to innovator products in these representative target populations. Changes in the approval process for generics should be accompanied by more consistent substitution practices. Pharmacists should notify the prescribing physician and patient whenever a critical-dose drug (generic or brand name) is dispensed in a different formulation from the one the patient has been taking. Therapeutic substitution for such drugs should not be made unless the prescribing physician has granted approval. The health care provider should consider instituting appropriate monitoring whenever patients are switched between generic formulations or between innovator drugs and generic formulations. Patients should be well informed about generic substitutes so that they can participate in treatment choices.

Anemia and cardiovascular complications: iron and EPO impact

Management of end-stage renal disease (ESRD) has been revolutionized by the advent of erythropoietin replacement. We briefly review its characteristics and clinical use. Also emphasized is the importance of iron deficiency in limiting the clinical response to erythropoietin therapy. Iron-replacement therapy in ESRD patients is briefly discussed.

Encephalopathy, hearing loss and retinal occlusions (Susac's syndrome): a new case

We describe a young woman with retinal arteriolar occlusions, encephalopathy, and hearing loss. At present this disorder is known as Susac's syndrome, a microangiopathy of the brain and retina whose pathogenesis is, however, unknown. The article reviews the clinical features of this rare, but not unusual, syndrome that can easily be misdiagnosed as multiple sclerosis.

Renal Na+, K+-ATPase in SHR: studies of activity and gene expression

The mechanism by which increased dietary intake of calcium reduces blood pressure in the spontaneously hypertensive rat is unknown. The present studies were designed to determine if there were alterations in the activity of the major membrane ion translocating pump, sodium, potassium-ATPase (NKA), in the kidneys of hypertensive rats and whether increased dietary calcium intake affected the activity of this enzyme. Fifteen-week old SHR's were found to have lower total ATPase activity in microsomal preparations from the kidney than age matched Wistar-Kyoto animals. Both the ouabain-sensitive component (NKA) and the ouabain-insensitive component were lower in SHR. Increasing dietary calcium intake from 1% to 3% elevated both components of the ATPase activity in SHR, but was without effect in WKY. Measurement of membrane phospholipid composition suggested that altered phospholipid composition did not account for the reduced ATPase activity observed, but indicated a reduced density of ATPase in SHR. A technique has been devised for qualitative and quantitative analysis of Na, K-ATPase alpha isoforms using RT-PCR. This technique reveals that the alpha 1 isoform is the sole catalytic isoform present in the nephron. Accurate and precise quantification of the amount of gene expression in individual nephron segments is reported and will be applied to determine whether dietary calcium influences blood pressure by a mechanism which alters nephron NKA gene expression.

Modeling and analysis of competitive RT-PCR

The present studies demonstrate a theoretical and practical framework for the accurate quantitation of gene expression in RNA extracted from microscopic tissue samples. The approaches are developed around competitive RT-PCR techniques. Assay performance has been examined and validated at both the RT and PCR steps. Our analysis of RT transcription efficiency for a number of native and competitor combinations shows that this property can differ, even for very similar templates. However, this difference is consistent and, once identified and measured, can be removed as an obstacle to accuracy. Using mathematical modeling, we have examined the simulated co-amplification of native and competitor templates in PCR. Useful insights have emerged from such modeling which indicate that differences in initial amplification efficiency and the rate of decay of amplification efficiency during the reaction can rapidly lead to inaccuracy, even while the slope and linearity of log plots of the competitor input and reaction product ratios are close to ideal. Finally, we show here that competitive RT-PCR reactions do not have to remain in the log-linear phase of PCR in order to accomplish accurate and precise quantification. Using appropriate competitors sharing primer binding sites and high internal sequence similarity, identical amplification efficiencies are preserved throughout the reaction. Reaction products, including heteroduplexes formed between native and competitor templates as reactions progress to plateau, can be identified and quantified accurately using the new technique of denaturing HPLC (dHPLC). This analytical technique allows the accuracy of competitive RT-PCR to be preserved beyond the linear phase. The technique has high sensitivity and precision and target abundances as low as 100 copies could be reliably estimated.