bluuebunny/crossref_metadata_2025 huggingface dataset:
Cortisol-Secreting Adrenal Adenomas Express 11β-Hydroxysteroid Dehydrogenase Type-2 Gene yet Possess Low 11β-HSD2 Activity
Authors: Mazzocchi Giuseppina , Aragona Francesco , Malendowicz Ludwik K. , Gottardo Lucia , Nussdorfer Gastone G.
Published: August 2007

Background

11β-hydroxysteroid dehydrogenase Type-2 (11β-HSD2) is an unidirectional enzyme that catalyzes the conversion of glucocorticoid hormones cortisol and corticosterone (B) into their corresponding inactive forms, cortisone, and 11-dehydrocorticosterone (DH-B). We have provided evidence that 11β-HSD2 is expressed as messenger RNA (mRNA) and protein in human adrenocortical cells, where its activity is inhibited in vitro by the main glucocorticoid agonists, adrenocorticotropic hormone (ACTH) and angiotensin-II. It seemed worthwhile, therefore, to study the gene expression and activity of 11β-HSD2 in cortisol-secreting adrenocortical adenomas.

Methods

Three adrenal adenomas that produced Cushing syndrome were recruited. Three normal adrenal glands were obtained from patients who underwent unilateral nephrectomy with ipsilateral adrenalectomy for renal cancer. 11β-HSD2 gene expression was studied by reverse transcription-polymerase chain reaction (RT-PCR) in adenoma and normal adrenocortical tissue. Cortisol, B, cortisone, and DH-B production by adenoma and adrenal slices in vitro was assayed by quantitative high-performance liquid chromatography (HPLC), and the activity of 11β-HSD2 was evaluated by measuring the conversion of [3H]-cortisol to [3H]-cortisone.

Results

RT-PCR allowed the detection of the 11β-HSD2 mRNA in the three adrenal adenomas and normal adrenal cortices examined. Under basal conditions, adenoma slices secreted higher amounts of cortisol and B, but markedly lower amounts of cortisone and DH-B than adrenal slices. ACTH raised cortisol and B production from both specimens, and it lowered cortisone and DH-B yield. The level basal conversion of [3H]-cortisol to [3H]-cortisone was notably less in adenomas than in adrenals, and ACTH decreased it in both tissues.

Conclusions

Collectively, our findings indicate that cortisol-secreting adrenal adenomas express the 11β-HSD2 gene, but the activity of the enzyme is suppressed in adenomas when compared with the normal adrenal cortex. We advance the hypothesis that the elevated local concentration of steroid hormones that occur in adenomas down-regulates 11β-HSD2 activity, thereby contributing to their abnormal steroidogenic function.
Beneficial Intervention of Experimental Colitis by Passive Cigarette Smoking through the Modulation of Cytokines in Rats
Authors: Ko Joshua Ka-Shun , Sham Ngai-Fung , Guo Xin , Cho Chi-Hin
Published: August 2007

Background

Epidemiologic observations have indicated that cigarette smoking decreases the risk of ulcerative colitis, but the modes of action remain anonymous. The present study aimed to investigate the beneficial effects of passive cigarette smoking using an animal colitis model. We hypothesized that the underlying mechanisms may involve immunoregulation of cytokines.

Methods

Experimental colitis was induced in rats by enema administration of 2,4-dinitrobenzene sulfonic acid (DNBS). Passive cigarette smoking by rats was performed for 1 hour once daily, from 3 days before DNBS enema until they were sacrificed on day 8. Other groups of DNBS-treated rats received therapeutic treatment of cyclosporin A or pentoxifylline, a tumor necrosis factor (TNF)-α inhibitor. Macroscopic and histologic damage were graded, and the colonic levels of different cytokines and the levels/activities of parameters related to neutrophil activation were also measured.

Results

DNBS-induced colonic damage was improved in passive-cigarette-smoking rats. This was accompanied by attenuation of the elevated colonic myeloperoxidase and inducible nitric oxide synthase activities and leukotriene B4 level. Likewise, the augmentation in colonic levels of TNF-α, interleukin (IL)-1β, and IL-6 in colitis rats was also alleviated by passive cigarette smoking. In contrast, the deprivation of colonic IL-10 during colitis was preserved in cigarette-smoking rats. These effects were similarly accomplished by pentoxifylline and, to some degree, by cyclosporin A.

Conclusions

The results support the idea that the beneficial effects of passive cigarette smoking in experimental colitis involved immunoregulation of cytokines in colonic tissues.
Circadian Phase Resetting in Older People by Ocular Bright Light Exposure
Authors: Klerman E.B. , Duffy J.F. , Dijk D.-J. , Czeisler C.A.
Published: August 2007

Background

Aging is associated with frequent complaints about earlier bedtimes and waketimes. These changes in sleep timing are associated with an earlier timing of multiple endogenous rhythms, including core body temperature (CBT) and plasma melatonin, driven by the circadian pacemaker. One possible cause of the age-related shift of endogenous circadian rhythms and the timing of sleep relative to clock time is a change in the phase-shifting capacity of the circadian pacemaker in response to the environmental light-dark cycle, the principal synchronizer of the human circadian system.

Methods

We studied the response of the circadian system of 24 older men and women and 23 young men to scheduled exposure to ocular bright light stimuli. Light stimuli were 5 hours in duration, administered for 3 consecutive days at an illuminance of ˜10,000 lux. Light stimuli were scheduled 1.5 or 3.5 hours after the CBT nadir to induce shifts of endogenous circadian pacemaker to an earlier hour (phase advances) or were scheduled 1.5 hours before the CBT nadir to induce shifts to a later hour (phase delays). The rhythms of CBT and plasma melatonin assessed under constant conditions served as markers of circadian phase.

Results

Bright light stimuli elicited robust responses of the circadian timing system in older people; both phase advances and phase delays were induced. The magnitude of the phase delays did not differ significantly between older and younger individuals, but the phase advances were significantly attenuated in older people.

Conclusions

The attenuated response to light stimuli that induce phase advances does not explain the advanced phase of the circadian pacemaker in older people. The maintained responsiveness of the circadian pacemaker to light implies that scheduled bright light exposure can be used to treat circadian phase disturbances in older people.
Adenosine and Hemodialysis in Humans
Authors: Guieu Régis , Brunet Philippe , Sampol Jérome , Bechis Guy , Fenouillet E. , Mege J.L. , Capo C. , Vitte J. , Ibrahim Z. , Carrega L. , Lerda D. , Rochat Hervé , Berland Yvon , Dussol Bertrand
Published: August 2007

Background

Infections and hypotension are serious complications that develop during hemodialysis (HD) treatment. Adenosine (ADO), a strong hypotensive and immunosuppressive agent, may participate in these two HD complications, because high concentrations of ADO metabolites are found in dialyzed human plasma. ADO, which is released by endothelial cells, is quickly transformed into inosine (INO) by plasmatic ADO deaminase (ADA) and mononuclear cell ADO deaminase (MCADA). In plasma, the degradation of ADO into INO and its uptake by red blood cells (RBC) are both very rapid, resulting in the short half-life of ADO in blood.

Methods

Using liquid chromatography, we evaluated ADO and INO plasma concentrations before and after HD session.

Results

Before the HD session, ADO and INO plasma concentrations were higher in hemodialyzed patients than in controls and in peritoneally dialyzed patients. At the end of the HD session, ADO plasma concentration was increased. ADO plasma concentration for the undialyzed patients was in the same range as that of the controls. Before HD, ADA activity was higher in hemodialyzed patients (559±349 IU) than in controls (219±48 IU), and the activity rose during the session (665±135 IU). ADA activity in the undialyzed patients (222±80 IU) was in the same range as that of the controls (219±48 IU). Before the HD session, the MCADA activity (247±144 IU) was lower than in controls (624±99 IU). HD did not modify ADO RBC uptake. ADO inhibited mononuclear cell proliferation and interferon-γ production in humans. Finally, as much as 50 μM INO does not inhibit ADO uptake by RBC and does not modify ADA and MCADA activities.

Conclusions

These data indicate that chronic HD inhibited MCADA activity and increased ADO plasma concentration. Both high ADO plasma concentration and low MCADA activity may be involved in dialysis-induced immune system failure and thereby favor infectious diseases.
Central Role of the Adipocyte in the Metabolic Syndrome
Authors: Bergman Richard N. , Van Citters Gregg W. , Mittelman Steven D. , Dea Melvin K. , Hamilton-Wessler Marianthe , Kim Stella P. , Ellmerer Martin
Published: August 2007

Insulin resistance is associated with a plethora of chronic illnesses, including Type 2 diabetes, dyslipidemia, clotting dysfunction, and colon cancer. The relationship between obesity and insulin resistance is well established, and an increase in obesity in Western countries is implicated in increased incidence of diabetes and other diseases. Central, or visceral, adiposity has been particularly associated with insulin resistance; however, the mechanisms responsible for this association are unclear. Our laboratory has been studying the physiological mechanisms relating visceral adiposity and insulin resistance. Moderate fat feeding of the dog yields a model reminiscent of the metabolic syndrome, including visceral adiposity, hyperinsulinemia, and insulin resistance. We propose that insulin resistance of the liver derives from a relative increase in the delivery of free fatty acids (FFA) from the omental fat depot to the liver (via the portal vein). Increased delivery results from 1) more stored lipids in omental depot, 2) severe insulin resistance of the central fat depot, and 3) possible regulation of visceral lipolysis by the central nervous system. The significance of portal FFA delivery results from the importance of FFA in the control of liver glucose production. Insulin regulates liver glucose output primarily via control of adipocyte lipolysis. Thus, because FFA regulate the liver, it is expected that visceral adiposity will enhance delivery of FFA to the liver and make the liver relatively insulin resistant. It is of interest how the intact organism compensates for insulin resistance secondary to visceral fat deposition. While part of the compensation is enhanced B-cell sensitivity to glucose, an equally important component is reduced liver insulin clearance, which allows for a greater fraction of B-cell insulin secretion to bypass liver degradation, to enter the systemic circulation, and to result in hyperinsulinemic compensation. The signal(s) resulting in B-cell up-regulation and reduced liver insulin clearance with visceral adiposity is (are) unknown, but it appears that the glucagon-like peptide (GLP-1) hormone plays an important role. The integrated response of the organism to central adiposity is complex, involving several organs and tissue beds. An investigation into the integrated response may help to explain the features of the metabolic syndrome.
Lowering of Circulating Free-Fatty Acids Levels and Reduced Expression of Leptin in White Adipose Tissue in Postobesity Status
Authors: Greco Aldo V. , Mingrone Geltrude , Vettor Roberto , Manco Melania , Rosa Giuseppina , Capristo Esmeralda , Federspil Giovanni , Castagneto Marco , Gasbarrini Giovanni
Published: August 2007

Background

Our aim was to investigate the regulation of the gene expression of leptin in subcutaneous adipose tissue biopsies in morbid obesity before and after biliopancreatic diversion (BPD).

Methods

Longitudinal study in morbidly obese subjects investigated twice: before and 6 months after BPD. Fourteen morbidly obese women, 37±13 years old and with a body mass index of 51.6±8.2 kg/m2, were studied before and 6 months after BPD (40.6±8.0 kg/m2). Using reverse transcriptase polymerase chain reaction analysis, the mRNA expression of leptin was investigated in adipose tissue. Plasma leptin was measured by radioimmunoassay; plasma insulin was measured by microparticle enzyme immunoassay. Free fatty acids (FFA) were measured using a colorimetric kit.

Results

A significant decrease in leptin mRNA level was observed in comparison with pretreatment in BPD patients (59±34 vs 143±85 arbitrary units, P <0.01). A strict relationship between adipose tissue leptin mRNA and plasma leptin either before ( R2=0.80, P <0.0001) or after BPD ( R2=0.86, P <0.0001) and between plasma FFA concentration and insulin either before ( R2=0.65, P <0.001) or after BPD ( R2=0.92, P <0.0001) was observed. Finally, a significant correlation was found between changes in FFA and insulin ( R2=0.64, P <0.001), insulin and leptin ( R2=0.88, P <0.0001), and insulin and leptin mRNA ( R2=0.83, P <0.0001).

Conclusion

These data demonstrate a high correlation between leptin mRNA expression in adipose tissue and plasma leptin in postobese subjects after BPD. The significant relationship between both leptin mRNA and plasma leptin with insulin suggests that circulating insulin might regulate leptin expression. It might be hypothesized that plasma FFA concentration can act on the insulin secretion and subsequently on the leptin secretory pathway.
Saliva Analysis in the Clinical Setting: Revisiting an Underused Diagnostic Tool
Authors: Nagler Rafael M. , Hershkovich Oded , Lischinsky Sophie , Diamond Eric , Reznick Abraham Z.
Published: August 2007

Background

One purpose of this study was to compare various biochemical and immunological parameters in blood and saliva that are routinely evaluated only in the blood for general medical requirements. Another purpose was to concomitantly compare these and other oral/salivary parameters differentially in whole, parotid, and submandibular and sublingual saliva to examine the source of those parameters and their specific concentrations.

Methods

Twelve healthy individuals (6 women, 6 men) were examined in the blood-saliva comparison study, and 30 healthy individuals (15 women, 15 men) were studied in the intersalivary comparison study.

Results

On the basis of the results we obtained, we suggest a classification scheme using a whole saliva compositional profile as a diagnostic tool in the evaluation of systemic and/or local pathologies. This system may be used to analyze various components of saliva beyond those analyzed in this study, thereby increasing the clinician/s ability to locate and assess specific pathologies. We also suggest that consideration be given to the use of compositional saliva analysis in the diagnosis of general medical conditions in which there is a high correlation between the salivary and blood concentrations of relevant components.

Conclusion

We think that saliva analysis is a useful, worthwhile diagnostic tool because saliva collection is noninvasive, easy, and inexpensive and may be performed by the patient with no need for the involvement of medical personnel, if so desired.
In Vivo Treatment with Granulocyte Colony-Stimulating Factor does not Delay Apoptosis in Human Neutrophils by Increasing the Expression of the Vacuolar Proton ATPase
Authors: Zimbelman Julie , Thurman Gail , Leavey Patrick J. , Ellison Misoo C. , Ambruso Daniel R.
Published: August 2007

Background

Neutrophils die by apoptosis, and in vivo administration of granulocyte colony-stimulating factor (G-CSF) delays this apoptotic cell death. G-CSF administered in vitro correlates delayed apoptosis with upregulation of the vacuolar proton ATPase (v-ATPase). Because this enzyme requires assembly of membrane and cytosolic domains to function, we hypothesized that in vivo G-CSF would increase synthesis and assembly of v-ATPase components to delay apoptosis.

Methods

Volunteers received G-CSF for 5 days, and each had a paired control. Neutrophils were isolated from subjects before the first and after the fifth injection. Proteins from cytosol or plasma membrane or from whole cell lysates were resolved by SDS-polyacrylamide gel electrophoresis and immunoblotted with antibody to the 33kDa v-ATPase E subunit. Densitometry quantified immunoreactivity.

Results

No significant increase on the E subunit occurred between treated and control groups.

Conclusion

In vivo G-CSF does not increase the amount of v-ATPase in neutrophils. Although G-CSF in vivo delays apoptosis, the mechanism(s) by which this occurs is not known.
Overexpression of the Complementary DNA for Human Glutamine: Fructose-6-Phosphate Amidotransferase in Mesangial Cells Enhances Glucose-Induced Fibronectin Synthesis and Transcription Factor Cyclic Adenosine Monophosphate-Responsive Element Binding Phosphorylation
Authors: Singh Lalit P. , Alexander Michelle , Greene Kenneith , Crook Errol D.
Published: August 2007

Hyperglycemia-induced alterations in mesangial cell function and extracellular matrix protein (ECM) accumulation are seen in diabetic glomerulopathy. The hexosamine biosynthesis pathway (HBP) is implicated in mediating several metabolic effects of high glucose (HG) in cells. This pathway converts fructose-6-phosphate to glucosamine (GlcN)-6-phosphate by the rate-limiting enzyme glutamine:fructose-6-phosphate amidotransferase (GFA). We have previously shown that metabolism of glucose through the HBP regulates the effects of glucose on ECM (fibronectin) synthesis and transcription factor (cyclic adenosine monophosphate-responsive element binding [CREB]) phosphorylation in SV-40-transformed rat kidney mesangial cells. UDP- N-acetyl-GlcN is the end product of the HBP and serves as a precursor for O-linked serine/threonine glycosylation of cytoplasmic and nuclear proteins. Here we show that culturing mesangial cells in HG and GlcN increases the level of O- N-acetylglucosamine in several cytoplasmic and nuclear proteins. Inhibition of O-glycosylation by benzyl-2-acetamido-2-deoxy-α-D-galactopyranoside blocks both HG and GlcN-induced fibronectin synthesis and CREB phosphorylation. To further support the hypothesis that the HBP mediates HG-induced ECM synthesis, a complementary deoxyribonucleic acid (DNA) for human GFA was stably expressed in mesangial cells. Mesangial and GFA-overexpressing cells were cultured in 5 to 25 mM glucose for 48 hours. GFA-overexpressing cells were more sensitive to glucose as they demonstrated increases in fibronectin and CREB phosphorylation at lower glucose concentrations than seen in control cells. In addition, the response to 25 mM glucose for both proteins was increased in GFA when compared with controls. There is no difference in DNA synthesis and cellular adenosine triphosphate levels between the two cell lines. These results suggest that the HBP is a glucose sensor and mediator of the effects of hyperglycemia in the diabetic mesangium.
Effect of Desirable Fasting Triglycerides on the Postprandial Response to Dietary Fat
Authors: Miller Michael , Zhan Min , Georgopoulos Angeliki
Published: August 2007

Background

The National Cholesterol Education Program (NCEP) recently revised the “desirable” fasting triglyceride (TG) to < 150 mg/dL, and levels exceeding 200 mg/dL are defined as “high.”

Methods

To evaluate the postprandial response to dietary fat, 50 studies were conducted in nonobese, normocholesterolemic subjects. Following an overnight fast, subjects consumed an oral fat load (70 g/m2), and postprandial triglyceride (ppTG) measurements were assessed at 2, 4, 6, and 8 hours. Subjects were divided by fasting TG cutpoints of 100 and 150 mg/dL.

Results

The prevalence of ppTG samples exceeding 200 mg/dL was significantly lower with fasting TG < 100 mg/dL ( n = 116) compared with TG 100 to 150 mg/dL ( n = 56) (8% versus 25%; p = .004, chi-square analysis). In addition, fasting TG < 100 mg/dL ( n = 29) was associated with a reduced mean 4-hour peak ppTG level compared with fasting TG > 100 mg/dL ( n = 21) (125 mg/dL versus 249.8 mg/dL; p < .0001). Multiple linear regression analysis identified fasting TG as the most important determinant of the postprandial response after adjustment for other covariates ( p = .0005).

Conclusions

Because ppTG-rich lipoproteins contribute to coronary heart disease risk, fasting TG < 100 mg/dL may be a more desirable cutpoint than fasting TG < 150 mg/dL in coronary heart disease risk factor assessment.
Gallium-Inducible Transferrin-Independent Iron Acquisition is a Property of Many Cell Types: Possible Role of Alterations in the Plasma Membrane
Authors: Olakanmi Oyebode , Stokes John B. , Britigan Bradley E.
Published: August 2007

Background

We have previously shown that human myeloid cell types can acquire large amounts of iron (Fe)3+from low-molecular-weight chelates by a process that is independent of adenosine triphosphate and dramatically increased by gallium (Ga) and other multivalent cationic metals.

Methods

To provide further insight into the mechanism responsible and its relevance to other cellular systems, we investigated Fe acquisition from nitrilotriacetic acid (NTA) by several myeloid and nonmyeloid cell lines in the presence and absence of Ga.

Results

Most nonmyeloid cells examined exhibited similar ability to acquire Fe from NTA. Ga increased the apparent maximum velocity (Vmax), with minimal changes in apparent Michaelis constant ( Km), of all cell lines. Both erythrocytes and erythrocyte ghosts acquired Fe from NTA, which increased with Ga exposure, analogous to nucleated cells. However, liposomes made from phospholipids did not exhibit Ga-inducible Fe association. Enzymes that modify surface proteins and carbohydrates did not alter HL-60 cell Fe acquisition. Modifying HL-60 membrane fatty acid content had only a minimal effect. Ga exposure did not change membrane potential or fluidity. However, electron microscopy suggested that Ga alters plasma membrane physical properties.

Conclusion

Multivalent cations appear to induce changes in cell membranes that may alter their interaction with Fe3+and probably other multivalent cations.
Parameters for Measurement of Oxidative Stress in Diabetes Mellitus: Applicability of Enzyme-Linked Immunosorbent Assay for Clinical Evaluation
Authors: Noiri Eisei , Tsukahara Hirokazu
Published: August 2007

Investigations of the mechanisms involved in the onset and progression of diabetes have recently confronted the role of reactive oxygen species (ROS) and oxidative stress. Prolonged exposure to hyperglycemic conditions induces nonenzymatic glycation of protein via the so-called Maillard reaction, resulting in Schiff-base products and Amadori products that engender ROS production. These processes initiate and exacerbate micro- and macrovascular complications in diabetes. Increased oxidative stress is induced by excessive ROS production and inadequate antioxidant defenses. Recently, oxidative stress status markers have been associated directly with the severity and prognosis of diabetes. To examine oxidative stress, reliable and high-throughput methods are needed to examine large numbers of clinical samples. The emerging availability of enzyme-linked immunosorbent assay (ELISA) for oxidative stress status markers allows its application to assessment of various pathophysiologic conditions, including diabetes. This review outlines the recent achievements of ELISA application for clinical studies elucidating oxidative stress. It introduces the potential applicability of ELISA for investigating oxidative stress in diabetes.
Host Cells Reduce Glucose Uptake and Glycogen Deposition in Response to Hepatic Insulin Gene Therapy
Authors: Porter Marty H. , Paveglio Sara A. , Zhang Jin-an , Olson Darin E. , Campbell Adam G. , Thulé Peter M.
Published: August 2007

Background

Hepatic insulin gene therapy (HIGT) restores weight gain and near-normal glycemia in rodent models of insulin- deficient diabetes mellitus. However, the effect of transgenic insulin on endogenous genes and recipient cell function is relatively unexplored. To investigate hepatocellular effects of transgenic insulin expression, we evaluated intermediary glucose metabolism in primary cultured hepatocytes treated with HIGT.

Methods

Rat hepatocytes were transduced with adenovirus expressing a glucose-responsive human insulin transgene and cultured in high-glucose and high-insulin conditions. We determined glycogen content in cell cultures and intact liver directly. Glycogenolysis was compared using glucose production of cultured cells. Glucose uptake, oxidative, and glycolytic processing were determined by radiotracer analysis or direct end-product assessment. Quantitative real-time reverse transcriptase polymerase chain reaction was used to determine expression of glucose transporter 2 (GLUT2) and glucokinase genes. GLUT2 protein abundance was determined by Western blot analysis.

Results

HIGT-treated hepatocytes contained significantly less glycogen than either untreated hepatocytes or those treated with an empty virus. Glucose release owing to glycogenolysis remained normal. However, HIGT treatment significantly impaired glucose uptake and processing. Metabolic synthetic processes were not generally inhibited, as indicated by enhanced β-hydroxybutyrate secretion. While preserving cell viability, HIGT treatment diminished expression of both glucokinase and GLUT2. In HIGT-treated streptozocin-treated diabetic rats, total liver glycogen was intermediate between diabetic animals and normal controls.

Conclusions

These results suggest gene-specific effects in recipient hepatocytes following HIGT treatment and underscore the need for expanded studies examining host cell responses to the transfer of metabolically active transgenes.
Outcomes of National Institutes of Health Peer Review of Clinical Grant Applications
Authors: Kotchen Theodore A. , Lindquist Teresa , Miller Sostek Anita , Hoffmann Raymond , Malik Karl , Stanfield Brent
Published: August 2007

Purpose

We previously reported that National Institutes of Health (NIH) peer review outcomes in 2002 were slightly but significantly less favorable for grant applications for clinical research than for laboratory research. The present analysis was undertaken to determine if factors related to the review process might contribute to this difference.

Methods

The impact of each of the following factors on median priority scores and funding rates for clinical and nonclinical R01 grant applications was evaluated: (1) the percentage of clinical applications assigned for review to a study section, (2) the requested direct costs, and (3) the clinical research experience of the reviewers.

Results

Confirming our previous observation, in both 1994 and 2004, median priority scores and funding rates for R01 applications were less favorable for clinical research. In 1994, clinical applications did not fare as well in study sections reviewing relatively low percentages of clinical applications. This was not the case in 2004. Although requested direct costs were greater for clinical than for nonclinical R01 applications, median priority scores within each category were actually more favorable for applications requesting greater funding. Assignment of priority scores was not different for reviewers with or without experience conducting clinical research.

Conclusion

These data do not support the hypothesis that the less favorable review outcomes for clinical applications are related to these review factors. We suggest that peer review outcomes for clinical research will benefit from the recent refinement of NIH review criteria, emphasizing the unique contributions of clinical investigation, and from increased training opportunities for clinical investigators.
Influence of the Dialysis Membrane on Markers of Tissue Ischemia
Authors: Carrega Louis , Giaime Philippe , Montserrat Colette , Vincente Olivia , Brunet Philippe , Dussol Bertrand , Berland Yvon , Guieu Regis
Published: August 2007

Background

Hemodialysis (HD) is often accompanied by adverse effects, such as tissue ischemia. We have already observed an increase in plasma adenosine (ADO) levels during HD sessions, which may be the result of tissue ischemia. Here we evaluate the influence of the dialysis membrane on two sensitive and early markers of ischemia: ADO and ischemia-modified albumin (IMA).

Methods

We included in the study 50 patients with end-stage renal failure, 39 hemodialyzed (mean age 61 ± 24 years; 24 male; membranes: 23 synthetic and 16 cellulose based) and 11 undialyzed (mean age 55 ± 12 years; 6 male), and 10 healthy subjects (mean age 47 ± 11 years; 4 male). We compensated for hemoconcentration during HD by measuring either the IMA to albumin (Alb) or the ADO to Alb ratio.

Results

Under basal conditions, the IMA to Alb ratio was not significantly different in patients and controls and HD did not significantly modify this ratio. Conversely, the ADO to Alb ratio (mean ± SD in μmol/g) was higher in patients before HD compared with either undialyzed patients or controls (before HD: 0.077 ± 0.02; undialyzed patients: 0.026 ± 0.11; controls: 0.022 ± 0.01). During HD, there was a significant increase in the ADO to Alb ratio (before HD: 0.077 ± 0.02; after HD: 0.09 ± 0.029; p < .01). We found no significant difference in the IMA to Alb or ADO to Alb ratio using either synthetic or cellulose-based membranes.

Conclusions

We concluded that ADO is a more sensitive marker of ischemia than IMA and that, under our HD conditions, the ischemia caused by HD was very weak, independent of the dialysis membrane.
Thiazolidinediones and Progression of Renal Disease in Patients with Diabetes
Authors: Goyal Abhijeet , Crook Errol D.
Published: August 2007

Objective

Thiazolidinediones (TZDs) are used in the treatment of type 2 diabetes mellitus (T2DM) and appear to have beneficial effects on markers of cardiovascular or renal risk that are independent of glycemic control. We examined the effects of TZDs on renal survival in a predominantly black population with T2DM.

Methods

We performed a retrospective case-control study in patients with T2DM seen in our nephrology clinic in 2001 to 2002. Cases had T2DM and were on a TZD at presentation or for ≥ 6 months over follow-up. Controls were matched for sex, age, duration of T2DM, and initial creatinine. Reaching end-stage renal disease (ESRD) was the primary end point.

Results

From 387 records, 43 cases (34 blacks, 31 females) and 106 controls (96 blacks, 83 females) were identified. The baseline characteristics were similar for both groups. Both groups had moderate renal disease (estimated glomerular filtration rate ≈ 40-45 mL/min). Cases had lower systolic blood pressure over follow-up (p = .02), but there was no difference in glycemic control or use of insulin. Renal survival was better among cases (age- and gender-adjusted odds ratio for reaching ESRD 0.17 [95% confidence interval 0.03-0.8]; p = .03). When adjusted for systolic blood pressure over follow-up, the tendency for improved renal survival in cases remained but was no longer significant.

Conclusion

We conclude that TZDs may protect against the progression of renal disease in T2DM. Prospective studies are required to determine the effects of TZDs on renal survival in T2DM.
Inducible Nitric Oxide Synthase Inhibitors Reduce Urinary Markers of Systemic Oxidant Stress in Murine Proliferative Lupus Nephritis
Authors: Njoku Chinedu J. , Patrick Kennerly S. , Ruiz Philip , Oates Jim C.
Published: August 2007

Background

Proliferative lupus nephritis (PLN) is characterized by increased expression of inducible nitric oxide (NO) synthase (iNOS). Inhibition of iNOS with NG-monomethyl L-arginine (L-NMMA) abrogates renal disease in two models of murine PLN, but the mechanism of this effect is unknown. Reactive oxygen species have both direct and indirect pathogenic effects in inflammatory lesions and are therefore potentially an important therapeutic target in PLN. We hypothesized that inhibition of iNOS activity would reduce ROS production in murine PLN.

Methods

A dose escalation of L-NMMA (0, 20, 100, and 500 mg/kg/day) was performed in New Zealand Black × New Zealand White F1 (NZB/W) mice with active renal disease. Twenty-four-hour urine nitrate + nitrite (NOX) was measured with a chemiluminescence NO analyzer. Twenty-four-hour urine 8-isoprostane F2α (8-iso-PGF2α) was measured by gas chromatography-negative ion chemical ionization mass spectrometry. MRL-MpJFASlpr (MRL/lpr) and NZB/W mice were divided into three groups and given either L-NMMA, L-N6-iminoethyl-lysine (L-NIL), or distilled water for 2 weeks. Urine NOX and 8-iso-PGF2α were determined after 2 weeks.

Results

L-NMMA reduced both urine NOX and 8-iso-PGF2α levels in a dose-dependent fashion in NZB/W and MRL/lpr mice. Urine NOX and 8-iso-PGF2α levels were highly correlated. Both specific (L-NIL) and nonspecific (L-NMMA) iNOS inhibition reduced urine NOX and 8-iso-PGF2α levels in both models of murine PLN.

Conclusion

These findings suggest that iNOS activity is a major source of reactive oxidant stress in these models of murine PLN. Future studies will address the pathogenic role of reactive oxygen stress in PLN.
Atrial Natriuretic Peptides: Anticancer Agents
Authors: Vesely David L.
Published: August 2007

Atrial natriuretic peptides (ANPs) consist of a family of six peptide hormones that are synthesized by three different genes and then stored as three different prohormones. Within the 126-amino acid ANP prohormone are four peptide hormones: long-acting natriuretic peptide (LANP), vessel dilator, kaliuretic peptide, and ANP, whose main known biologic properties are blood pressure regulation and maintenance of plasma volume. The newest discovered property of these peptide hormones is their anticancer effects. Vessel dilator, LANP, kaliuretic peptide, and ANP decrease the number of human pancreatic adenocarcinoma cells in culture by 65%, 47%, 37%, and 34%, respectively, within 24 hours at their 1 μM concentrations. Similar results have been found with breast adenocarcinomas, squamous cell lung cancer, and small cell lung cancer cells, each associated with an 83% or greater inhibition of deoxyribonucleic acid (DNA) synthesis by these four peptide hormones. Brain natriuretic peptide has no effects even when increased 100-fold (ie, 100 μM). C-type natriuretic peptide has no effects when increased 10-fold, but when increased 100-fold, it decreases 39% of the cancer cells. At this higher 100 μM concentration, vessel dilator kills 92% of the cancer cells within 24 hours. The four peptide hormones synthesized by the ANP gene given subcutaneously via osmotic pumps in athymic mice with human pancreatic adenocarcinomas completely stop the growth of these adenocarcinomas at 1 week. Vessel dilator, LANP, and kaliuretic peptide within 1 week decrease the volume by 49%, 28%, and 11% of the human pancreatic adenocarcinomas, which, with current anticancer treatment, have a mean survival of only 4 months.
Natriuretic Peptides in Acute and Chronic Kidney Disease and during Renal Replacement Therapy
Authors: Hörl Walter H.
Published: August 2007

Plasma levels of natriuretic peptides are elevated in patients with chronic kidney disease owing to impairment of renal function, hypertension, hypervolemia, and/or concomitant heart disease. Proteinuria and/or immunosuppression also contribute to enhanced plasma levels and increased urinary excretion of natriuretic peptides. Atrial natriuretic peptide (ANP) and particularly brain natriuretic peptide (BNP) levels are linked independently to left ventricular mass and function and predict total and cardiovascular mortality. ANP and BNP decrease significantly during hemodialysis treatment but increase again during the interdialytic interval. Intraperitoneal administration of ANP decreases peritoneal fluid and glucose absorption, as well as lymphatic flow rate. Successful kidney transplant normalizes the plasma levels of natriuretic peptides in the majority of patients. In experimental animals but not in humans, ANP administration protects against ischemic acute renal failure. Since proANP31-67 peptide does not cause hypotension, this vessel dilator may protect the kidney during acute renal failure by intrarenal vasodilation and stimulation of endogenous prostaglandin E2 synthesis.
Determinants of Natriuretic Peptide Production by the Heart: Basic and Clinical Implications
Authors: de Bold Adolfo J. , Kuroski de Bold Mercedes L.
Published: August 2007

The cardiac natriuretic peptides (NPs) atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) are polypeptide hormones synthesized, stored, and secreted by cardiac muscle cells (cardiocytes). The NPs modulate extracellular fluid volume and blood pressure and have potent growth-regulating properties, which make them of great interest for cardiac remodeling in acute myocardial infarction and congestive heart failure. We have observed that the production of NP can be coordinately or discoordinately regulated. In the former type, muscle stretch-elicited secretion triggers signals mediated by Gi/o protein, whereas agonists such as endothelin 1 independently signal through Gq. Discoordinated regulation is observed following stimulations by some cytokines, which selectively up-regulate BNP. This regulation takes place at the translational and transcriptional levels and is dependent on a p38 signaling pathway. Further details of processes regulating NP secretion need to be defined to develop a comprehensive view of the endocrine function of the heart. Nevertheless, translational research in the area of NPs has demonstrated the usefulness of these hormones as a marker of disease and as potential therapeutic agents. The latter application of NP is particularly attractive given that ANF and BNP possess pharmacologic actions that require polypharmacy in the treatment of acute myocardial infarction and congestive heart failure.
Guanosine Triphosphatase Activation Occurs Downstream of Calcineurin in Cardiac Hypertrophy
Authors: Richardson Kenneth E. , Tannous Paul , Berenji Kambeez , Nolan Bridgid , Bayless Kayla J. , Davis George E. , Rothermel Beverly A. , Hill Joseph A.
Published: August 2007

There is great interest in deciphering mechanisms of maladaptive remodeling in cardiac hypertrophy in the hope of affording clinical benefit. Potential targets of therapeutic intervention include the cytoplasmic phosphatase calcineurin and small guanosine triphosphate-binding proteins, such as Rac1 and RhoA, all of which have been implicated in maladaptive hypertrophy. However, little is known about the interaction—if any—between these important signaling molecules in hypertrophic heart disease. In this study, we examined the molecular interplay among these molecules, finding that Rho family guanosine triphosphatase signaling occurs either downstream of calcineurin or as a required, parallel pathway. It has been shown that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibition blocks hypertrophy, and we report here that “statin” therapy effectively suppresses small G protein activation and blunts hypertrophic growth in vitro and in vivo. Importantly, despite significant suppression of hypertrophy, clinical and hemodynamic markers remained compensated, suggesting that the hypertrophic growth induced by this pathway is not required to maintain circulatory performance.
Role of the Mitogen-Activated Protein Kinases in Cytokine-Mediated Inhibition of Insulin Gene Expression
Authors: Chin-Chance Catherine V.T. , Newman Marsha V. , Aronovitz Amy , Blomeier Herman , Kruger Jessica , Lee Eun-Jig , Lowe William L.
Published: August 2007

Background

Following islet transplant, inflammatory cells in the vicinity of the transplant graft elaborate cytokines that contribute to islet graft dysfunction. To better understand the mechanism for this effect of cytokines on graft function, we examined the impact of cytokines on intracellular signaling and insulin promoter activity in pancreatic beta cells.

Methods

Two pancreatic beta cell lines, RINm5F and MIN6 cells, were transfected with a rat insulin promoter (RIP) luciferase fusion gene and treated with a combination of cytokines, including 5 ng/mL interleukin-1β + 10 ng/mL tumor necrosis factor α + 25 ng/mL interferon-γ. The effect of cytokines on beta cell transcription factors and signaling pathways was analyzed by real-time reverse transcriptase polymerase chain reaction and Western blotting.

Results

Treatment for 48 hours with the combination of cytokines decreased insulin 1 messenger ribonucleic acid (mRNA) levels to 51% and 38% and RIP1 activity to 16% and 30% of control levels in RINm5F and MIN6 cells, respectively. The level of mRNAs encoding transcription factors important for insulin gene expression and beta cell function, including MafA, PDX-1, Nkx6.1, and Pax6, was also decreased by cytokine treatment. Cytokines increased phosphorylation of ERK and c-Jun NH2-terminal kinase (JNK) in RINm5F and MIN6 cells but had no effect on p38 kinase phosphorylation. Neither JNK nor ERK inhibition had a significant effect on cytokine-mediated inhibition of RIP1 activity.

Conclusion

Beyond modulating beta cell survival, cytokines inhibit insulin promoter activity, which likely contributes to islet dysfunction following islet transplant. This effect appears to be mediated, in part, via altered expression of transcription factors important for insulin gene expression.
Preparing Data for Analysis Using Microsoft Excel
Authors: Elliott Alan C. , Hynan Linda S. , Reisch Joan S. , Smith Janet P.
Published: August 2007

A critical component essential to good research is the accurate and efficient collection and preparation of data for analysis. Most medical researchers have little or no training in data management, often causing not only excessive time spent cleaning data but also a risk that the data set contains collection or recording errors. The implementation of simple guidelines based on techniques used by professional data management teams will save researchers time and money and result in a data set better suited to answer research questions. Because Microsoft Excel is often used by researchers to collect data, specific techniques that can be implemented in Excel are presented.
Intradermal Capsaicin Causes Dose-Dependent Pain, Allodynia, and Hyperalgesia in Humans
Authors: Scanlon Graham C. , Wallace Mark S. , Ispirescu Sorin J. , Schulteis Gery
Published: August 2007

Background

Intradermal capsaicin is a human pain model that produces reliable pain and sensitization. This model facilitates controlled testing of analgesic efficacy via a crossover design while minimizing confounding variables in clinical pain states and retaining sufficient power with small samples.

Methods

To determine the lowest dose of capsaicin that produces consistent neurosensory measures, we administered 0.1, 1, 10, or 100 μg to healthy volunteers in a blinded manner ( N = 19). Pain scores were recorded at 0, 5, 10, 15, and 60 minutes on a visual analog scale from 0 to 100. Areas and intensities of mechanical allodynia (foam brush stimulus) and pinprick hyperalgesia (von Frey test) were quantified at 15 and 60 minutes, as were flare areas.

Results

Capsaicin produced dose-dependent increases in spontaneous pain ( p = .013), the area and intensity of mechanical allodynia ( p = .006 and p < .001, respectively), the area and intensity of pinprick hyperalgesia ( p = .010 and p = .014, respectively), and the flare area ( p = .010). The 10 μg dose produced greater spontaneous pain than the 1 μg dose ( p = .017). The 100 μg dose produced greater spontaneous pain than the 10 μg, but the difference was not statistically significant.

Conclusion

The 10 and 100 μg capsaicin doses produced robust pain measures across a range of modalities, and lower doses produced minimal effects. Whereas most studies use 100 μg, using a lower dose is reasonable and may facilitate detection of subtle analgesic effects—particularly with nonopioid analgesics—and drugs can be tested in lower doses, minimizing adverse side effects.
Diagnosis and Treatment of Peripheral Arterial Disease Compared with Other Atherosclerotic Vascular Diseases in a University Primary Care Clinic
Authors: Ismail Hassan M. , Jackson Kyoo , Smith Daniel
Published: August 2007

Background

Despite the fact that peripheral arterial disease (PAD) significantly increases the risk of cardiovascular mortality, it is significantly underdiagnosed and undertreated. The purpose of this study was to evaluate the practice at a northeast Tennessee university primary care clinic regarding the diagnosis and treatment of PAD.

Methods

A retrospective medical record survey was conducted to evaluate practice patterns in diagnosing and treating PAD in a university primary care clinic. A clinic population of 711 patients was selected using International Classification of Diseases-9 codes for coronary artery disease (CAD), cerebovascular disease (CVD), and/or PAD. A sample of 180 patients (25.3%) was randomly selected using a systematic statistical method. Of these, 125 patients met the diagnostic criteria for CAD, CVD, and/or PAD. The study covered a 3-year period, from July 2001 until June 2004. Demographic and other data, including the use of antiplatelet therapy, were collected.

Results

One hundred ten patients met all of the inclusion and exclusion criteria. Thirty-nine percent were males, and 61% were females. Overall, 79% had CAD, 53% had CVD, and 25% had PAD. Almost half of the patients had some combination of these. Only about 2% had PAD only compared with 36% with CAD only and 17% with CVD only. Although the prevalence of CAD and CVD (among other atherosclerotic vascular diseases) in our clinic was comparable to national figures, the prevalence of PAD was significantly lower ( p = .004). The overall use of any antiplatelet agent was 84.2% for patients with only CAD and 80% for only CVD. There was not an adequate number of patients with only PAD to evaluate the use of antiplatelet therapy in this group.

Conclusion

The low prevalence of PAD only (most PAD patients had coexisting CAD and CVD) indicates that PAD is underdiagnosed at our clinic. There was suboptimal use of aspirin and other antiplatelet drugs among patients with atherosclerotic vascular disease.