Mitochondrial DNA damage and altered membrane potential (delta psi) in pancreatic acinar cells induced by reactive oxygen species

BACKGROUND

Reactive oxygen species (ROS) have been implicated in the induction of acute pancreatitis. Mitochondria possess a distinct genome (mtDNA) that is more susceptible to ROS-induced damage than nuclear DNA (nDNA). The purpose of our study was to determine the effect of ROS on mitochondrial function and membrane potential (delta psi mt), to identify signal transduction mechanisms activated by ROS, and to quantify damage to mtDNA in an in vitro pancreatitis model.

METHODS

Pancreatic acinar cells, AR4-2J, were treated with saline solution (control) or hydrogen peroxide (H2O2), a representative ROS. Mitochondrial function was assessed with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay; to determine delta psi mt, rhodamine-123 uptake was measured. Intracellular calcium levels and c-Jun N-terminal kinase activity was determined; gel mobility shift assays were performed to assess induction of the transcription factor NF-kappa B. To quantitate DNA damage, a novel polymerase chain reaction-based procedure was performed.

RESULTS

Mitochondrial function and delta psi mt were significantly decreased with oxidative damage. H2O2 treatment resulted in increased intracellular calcium levels, activation of c-Jun N-terminal kinase, and induction of NF-kappa B DNA binding. Treatment of AR4-2J cells with H2O2 resulted in selective mtDNA damage; nDNA was not affected.

CONCLUSIONS

Our data demonstrate that pancreatic mtDNA is more susceptible to oxidative damage than nDNA; this damage is associated with decreases in mitochondrial function and delta psi mt and activation of downstream signal transduction pathways. Mitochondrial damage mediated by ROS may play a central role in pancreatic cell injury associated with acute pancreatitis.

Glyphosate effects on phenolic metabolism of nodulated soybean (Glycine max L. merr.)

Glyphosate is a herbicide that blocks the shikimic acid pathway. Three Bradyrhizobium japonicum strains with different sensitivities to glyphosate were used to test the effect of this herbicide on the phenolic metabolism of nodulated soybeans and on the bacteroid nitrogenase activity. Glyphosate caused an inhibition in the bacteroid nitrogenase activity that was related with the sensitivity of the nodule-forming strains. Both leaves and nodules accumulated huge amounts of shikimate and phenolic acids (mainly protocatechuic acid), indicating that the herbicide was translocated to the nodule and disturbed phenolic metabolism. However, this accumulation was not clearly related to the sensitivity of the different strains. Bacteroids from control plants were incubated with the same concentration of shikimate, and phenolic acid accumulated in glyphosate-treated plants. Despite the high levels found in nodules, they were not responsible for the decrease of the nitrogenase activity. Glyphosate by itself caused a small inhibition of the bacteroid nitrogenase activity.

Gastroesophageal reflux in diabetes mellitus

OBJECTIVE

Although abnormal gastroesophageal (GE) reflux is the most frequent alteration of the gastrointestinal tract, its prevalence in diabetes mellitus (DM) is not widely known. The objective of this study was to analyze both the presence of abnormal GE reflux in diabetic patients with no esophageal symptoms and the influence of cardiovascular autonomic neuropathy (CVAN) in the development of abnormal GE reflux.

METHODS

Fifty insulin-dependent diabetic patients, averaging 29.2 +/- 9.0 yr of age, who had had diabetes for > 5 yr and showed no symptoms or history of gastroesophageal disease, were compared with a control group composed of 36 healthy volunteers (18 men, 18 women) whose average age was 35.9 +/- 10.1 yr. The cardiovascular autonomic nervous system was examined in the diabetics and control subjects who complied with inclusion criteria. Long-term (24-h) ambulatory esophageal pH monitoring was performed, as well as a manometric study of the lower esophageal sphincter.

RESULTS

The parameters obtained from the monitoring showed significant differences (p < 0.01) between DM and control subjects. Abnormal GE reflux, defined as any percentage of time with esophageal pH < 4 exceeding 3.5% of total time (8.7 +/- 5.6%; range, 4.1-24.4%), was detected in 14 patients. Diabetic subjects were classified according to cardiovascular autonomic neuropathy tests (without CVAN [n = 19, 38%] and with abnormal CVAN tests [n = 31, 62%]). The pH monitoring parameters showed significant differences between these two groups (p < 0.05).

CONCLUSIONS

A higher prevalence (28%) of abnormal GE reflux appeared among asymptomatic diabetic patients than among the general population. The presence of abnormal GE reflux in diabetic patients was associated with the existence of cardiovascular autonomic neuropathy (abnormal GE reflux = 38.7% in diabetic patients with abnormal CVAN tests vs 10.5% in diabetic patients without CVAN).

Pregnant rat uterus expresses high levels of the type 3 iodothyronine deiodinase

Although thyroid hormones are critically important for the coordination of morphogenic processes in the fetus and neonate, premature exposure of the embryo to levels of the hormones present in the adult is detrimental and can result in growth retardation, malformations, and even death. We report here that the pregnant rat uterus expresses extremely high levels of the type 3 iodothyronine deiodinase (D3), which inactivates thyroxine and 3,3', 5-triiodothyronine by 5-deiodination. Both D3 mRNA and activity were present at the implantation site as early as gestational day 9 (E9), when expression was localized using in situ hybridization to uterine mesometrial and antimesometrial decidual tissue. At later stages of gestation, uterine D3 activity remained very high, and the levels exceeded those observed in the placenta and in fetal tissues. After days E12 and E13, as decidual tissues regressed, D3 expression became localized to the epithelial cells lining the recanalized uterine lumen that surrounds the fetal cavity. These findings strongly suggest that the pregnant uterus, in addition to the placenta, plays a critical role in determining the level of exposure of the fetus to maternal thyroid hormones.

Long-term prognosis in women with normal dobutamine stress echocardiography

Although the long-term prognosis for patients with a normal dobutamine stress echocardiographic result is good, most studies have focused on men. We assessed the long-term cardiac prognosis for women by reviewing the cases of 100 women who underwent dobutamine stress echocardiography for suspected coronary artery disease and found that women with a normal result have an excellent long-term cardiac prognosis.

Left ventricular diastolic function in normal human pregnancy

BACKGROUND

Little information is available about changes in left ventricular diastolic function during pregnancy. We used mitral inflow and pulmonary venous flow profiles to evaluate left ventricular diastolic function in 37 healthy pregnant women 26 to 41 years old (mean, 32 years).

METHODS AND RESULTS

Echocardiographic studies were performed at the end of each trimester. Eight subjects (control group) underwent similar testing 1 to 3.5 months (mean, 1.7 months) postpartum. During pregnancy, the cardiac output increased significantly as a result of an increased heart rate and, to a lesser degree, stroke volume. Significantly decreased systemic vascular resistance and increased left ventricular mass were also noted. Peak mitral flow velocity in early diastole (E) increased 13. 3% during the first trimester and remained at the high end of normal throughout pregnancy. Peak A-wave velocity (A) increased maximally in the third trimester. Compared with control subjects, first-trimester subjects had a significantly increased E/A ratio. The ratio subsequently decreased, reflecting the augmented A-wave velocity. Pulmonary venous peak systolic forward flow velocity increased, peaking in the second trimester (nonsignificant), but returned to baseline levels postpartum. The pulmonary venous diastolic time-velocity integral decreased significantly from the first to the third trimester. Peak pulmonary venous reverse flow velocity at atrial contraction increased significantly, without being markedly changed in duration.

CONCLUSIONS

Pregnancy, a chronic, natural volume-overload state, has important effects on hemodynamic and echocardiographic variables. Based on pulmonary venous flow and left ventricular inflow velocities, our results provide a standard reference concerning diastolic filling dynamics by trimester.

Fps1p controls the accumulation and release of the compatible solute glycerol in yeast osmoregulation

The accumulation of compatible solutes, such as glycerol, in the yeast Saccharomyces cerevisiae, is a ubiquitous mechanism in cellular osmoregulation. Here, we demonstrate that yeast cells control glycerol accumulation in part via a regulated, Fps1p-mediated export of glycerol. Fps1p is a member of the MIP family of channel proteins most closely related to the bacterial glycerol facilitators. The protein is localized in the plasma membrane. The physiological role of Fps1p appears to be glycerol export rather than uptake. Fps1 delta mutants are sensitive to hypo-osmotic shock, demonstrating that osmolyte export is required for recovery from a sudden drop in external osmolarity. In wild-type cells, the glycerol transport rate is decreased by hyperosmotic shock and increased by hypo-osmotic shock on a subminute time scale. This regulation seems to be independent of the known yeast osmosensing HOG and PKC signalling pathways. Mutants lacking the unique hydrophilic N-terminal domain of Fps1p, or certain parts thereof, fail to reduce the glycerol transport rate after a hyperosmotic shock. Yeast cells carrying these constructs constitutively release glycerol and show a dominant hyperosmosensitivity, but compensate for glycerol loss after prolonged incubation by glycerol overproduction. Fps1p may be an example of a more widespread class of regulators of osmoadaptation, which control the cellular content and release of compatible solutes.

Ablating the ischemia-reperfusion injury in non-heart-beating donor kidneys

BACKGROUND

The objective of this study was to determine if allopurinol (AL) and/or trifluoperazine (TFP) added to the Belzer machine preservation solution (MPS) improves the function of non-heart-beating donor (NHBD) canine kidneys.

METHODS

Anesthetized canines underwent bilateral dissection of the renal vessels, obtaining baseline flow. After removing one kidney (heart-beating donor [HBD]), the dog was exsanguinated. After remaining in situ for 120 min (30-min warm ischemia time, 90-min cold ischemia time), the second kidney was removed (NHBD), flushed, biopsied, and weighed. The kidneys were machine-perfused separately for 20 hr, and pressure, flow, and resistance were measured serially. The kidneys were randomly assigned to a perfusate group (G): G1=MPS, G2=MPS+TFP, G3=MPS+AL, and G4=MPS+TFP+AL. Kidneys were implanted separately into a single recipient dog. Flow, resistance, and urine output were measured serially for 4 hr. Blood and urine samples and kidney biopsies were then obtained. All measurements were standardized to 100 g of kidney weight.

RESULTS

HBD kidneys functioned better than NHBD kidneys in all groups, as expected. Although perfusate G1 was the most effective solution for HBD kidneys, the TFP additive (perfusate G2) more effectively reversed the vasospastic effects of ischemia/reperfusion for NHBD than the MPS solution (G1) with or without other additives. In HBD kidneys, the addition of AL resulted in the best creatinine clearance; however, AL was less effective than MPS alone in NHBD kidneys. TFP+AL together were completely ineffective in preserving renal function, regardless of whether the kidneys were from HBD or NHBD.

CONCLUSIONS

MPS+TFP more effectively protected renal function against reperfusion injury in the NHBD than MPS alone, AL, or AL+TFP. AL exerts a salutary effect on creatinine clearance in HBD but not in the NHBD. The TFP and AL combination should not be used together with the MPS in machine preservation of kidneys.

Fast partial-differential synthesis of the matching polynomial of C72-100

The Thesis algorithm uses partial-differential edge operators and a grammatical structure to generate and avoid expanding the Matching Polynomial. To run the algorithm efficiently, the vertexes of fullerene graphs C60-100 were sorted into three-dimensional sectors.

High phosphate level directly stimulates parathyroid hormone secretion and synthesis by human parathyroid tissue in vitro

Phosphate retention plays an important role in the pathogenesis of secondary hyperparathyroidism in patients with renal failure. In in vitro studies, high extracellular phosphate levels directly stimulate PTH secretion in rat and bovine parathyroid tissue. The present study evaluates the effect of high phosphate levels on the secretion of PTH and the production of prepro PTH mRNA in human hyperplastic parathyroid glands. The study includes parathyroid glands obtained from patients with primary adenomas and from hemodialysis and kidney-transplant patients with diffuse and nodular secondary hyperplasia. The experiments were performed in vitro using small pieces of parathyroid tissue. The ability of high calcium levels to decrease PTH secretion was less in adenomas than in secondary hyperplasia; among the secondary hyperplasia, nodular was less responsive to an increase in calcium than diffuse hyperplasia. In diffuse hyperplasia, PTH secretion was increased in response to 3 and 4 mM phosphate compared with 2 mM phosphate, despite a high calcium concentration in the medium; prepro PTH mRNA levels increased after incubation in 4 mM phosphate. Similar results were obtained with nodular hyperplasia, except that the elevation of PTH secretion in response to 3 mM phosphate did not attain statistical significance. In adenomas, high calcium concentrations (1.5 mM) did not result in inhibition of PTH secretion, independent of the phosphate concentration, and the prepro PTH mRNA was not significantly increased by high phosphate levels. In conclusion, first, the PTH secretory response to an increase in calcium concentration is less in nodular than diffuse hyperplasia; second, high phosphate levels directly affect PTH secretion and gene expression in patients with advanced secondary hyperparathyroidism.

Neovascularization by cardiomyoplasty

Nowadays cardiomyoplasty is used in cases of cardiac insufficiency as an alternative to cardiac transplant for patients with very developed ischemic cardiopathy, refractory to pharmacological treatment and without possibility of revascularization by using conventional techniques.

OBJECTIVES

Our Cardiovascular Research Group has proposed as an objective, the detection of any possible myocardial neovascularization through the muscle used for cardiomyoplasty. In the case that there are new blood vessels to the diseased myocardium through the latissimus dorsi muscle flap in which it is wrapped and which aids it mechanically, it would be possible to confirm the working hypothesis that cardiomyoplasty not only improves the cardiocirculatory function mechanically but also facilitates a better blood flow to the ischemic myocardium.

MATERIALS AND METHODS

The cardiomyoplasty technique is described using an experimental model of myocardial ischemia. The vascular cast is achieved by injecting methacrylate simultaneously into both the coronary tree and the wide dorsal muscle. In 15 experiments the connections between the coronary vascular system and the vascular structure of the latissimus dorsil muscle flap are demonstrated by several methods.

CONCLUSIONS

We have demonstrated that cardiomyoplasty, as well as improving ventricular function, favours the revascularization of the myocardium. Cardiomyoplasty could be indicated for cases of ischemic cardiopathy in patients in whom it is not possible to perform direct revacularization using conventional methods.

Stereoscopic visualization of three-dimensional ultrasonic data applied to breast tumours

OBJECTIVE

This paper presents a technique for stereoscopic visualization applied to three-dimensional (3D) ultrasonic breast data.

METHODS

A motorized acquisition system has been designed to translate regularly a linear-phased array transducer, in order to provide a series of parallel echographic slices of the breast. During acquisition, the breast is compressed between a plane support and a plexiglass plate to avoid breast motion. A window in this plate provides access for ultrasonic exploration. From the series of cross-sectional scans, a 3D volume is formed by interpolation between the successive ultrasonic images. A stereoscopic computer-graphic method has been developed to visualize these 3D ultrasonic data. Two conical transparent projections of the volume are computed from two slightly different viewpoints. These two projections make up the stereoscopic pair. This pair is displayed on a stereoscopic monitor for the visualization of the 3D data with the depth dimension.

RESULTS

The acquisition system and the method for computing the stereo-echograms were validated using an agar gel phantom. In vivo breast experiments were also performed.

CONCLUSION

Visualization of stereo-echographic projections improves the perception of depth and shape of breast tumours.

Pituitary apoplexy: a transient benign presentation mimicking mild subarachnoid hemorrhage with negative angiography

We report on a patient who presented with isolated transient headache as the only manifestation of pituitary apoplexy. A high index of suspicion and MRI led to the diagnosis. Copyright 1998 Lippincott Williams & Wilkins

Rapid diagnosis of extrapulmonary tuberculosis by ligase chain reaction amplification

A rapid amplification-based test for the diagnosis of extrapulmonary tuberculosis, the LCx Mycobacterium tuberculosis Assay from Abbott Laboratories, was evaluated. Results from the LCx M. tuberculosis Assay were compared with those from culture and the final clinical diagnosis for each patient. A total of 526 nonrespiratory specimens from 492 patients were tested. The specimens included urine; feces; lymph node exudates; pleural, cerebrospinal, articular, and ascitic fluids; tissue biopsies; gastric aspirates; purulent exudates; blood; and bone marrow aspirates. After combination of the culture results and the patient's clinical data, a total of 135 specimens were collected from 122 patients with a diagnosis of extrapulmonary tuberculosis. The sensitivity, specificity, and positive and negative predictive values for the LCx M. tuberculosis Assay were 77.7, 98.7, 95.2, and 93.1%, respectively; these values rose in resolved cases of TB to 78.5, 100, 100, and 93.1%, respectively. For 37 (27.4%) specimens from patients smear positive for the disease and 98 (72.6%) specimens from patients smear negative for the disease, the sensitivities of the LCx M. tuberculosis Assay were 100 and 71.1%, respectively. Statistically significant differences (P < 0.01) in sensitivities were found between culture and the LCx M. tuberculosis Assay. These differences were even greater among smear-negative specimens. The results demonstrate that the LCx M. tuberculosis Assay will provide rapid and valuable information for the diagnosis of extrapulmonary tuberculosis.

Descending cervical mediastinitis

Descending cervical mediastinitis is an uncommonly reported presentation of infection originating in the head or neck and descending into the mediastinum, which is fraught with impressive morbidity and mortality rates of 30% to 40% or more. We present the INOVA-Fairfax-Alexandria Hospital experience with descending cervical mediastinitis, January 1, 1986, to April 1, 1997; in addition we review the English-language medical and surgical literature with regard to this entity. Computed tomography and magnetic resonance imaging serve to aid both diagnosis and management. The application of broad-spectrum antibiotics should initially be empiric, with an eye to coverage of mixed aerobic and anaerobic infections. Definitive treatment mandates early and aggressive surgical intervention. All affected tissue planes, cervical and mediastinal, must be widely debrided, often leaving them open for frequent packing and irrigation. The treating physician must remain always alert to the further extension of infection, which, if it occurs, must be further debrided and drained. Tracheostomy serves a dual role of further opening cervical fascial planes and securing an often compromised airway.

Relevant residues of DRbeta1 third hypervariable region contributing to the expression and to severity of rheumatoid arthritis (RA) in Mexicans

Rheumatoid arthritis (RA) is a chronic autoimmune disease leading to destruction of the joints. Residues at positions 67-74 of the DRB1 third hypervariable region are involved in susceptibility (S) and resistance (P) to RA. DNA from 83 patients and 175 controls, all of them Mexican Mestizos were oligotyped using PCR-SSOP and PCR-SSP. The (S) alleles are DRB*0404 (p = 0.000004), *0401 (p = 0.007) and *1001 (p = 0.008). Those associated with P are DRB1*0701 (p = 0.0001); *1101 (p = 0.01); *1503 (p = 0.02); *0801 (p = 0.04); *1401 (p = 0.04). Susceptibility/protection are recessive traits; SS genotypes are increased in the patients (p = 0.0003) while PP genotypes are decreased in them (p = 0.00004). The motif at 67-74 and the valine or glycine at position 86 are relevant in the development and severity of RA in Mexicans. The associations suggest that residues 67, 70, 71 are central for susceptibility. The P alleles have D-70 or carry V-86 in the absence of D-70. Thus, susceptibility/protection depends on the combination of basic residues at these positions and a non-polar aa at 86 contributes to resistance. Severity is also HLA influenced. DQA1*03011-DQB1*0302 are associated to severe lesions in the presence of any DR4 subtype. Analyzing different ethnic groups is essential to elucidate the etiopathogenesis of RA.

Delapril slows the progression of atherosclerosis and maintains endothelial function in cholesterol-fed rabbits

The renin-angiotensin system is an important modulator of arterial blood pressure and inhibitors of the angiotensin-converting enzyme (ACE-Is) and are currently used in the treatment of hypertension. The pleiotropic actions exerted by angiotensin II (AngII) on the functionality of the vessel wall may have pro-atherosclerotic outcomes; evidence for an anti-atherosclerotic effect of ACE-Is has been presented and an antioxidant effect has been attributed to thiol-containing ACE-Is, like Captopril. The present study has been undertaken to investigate the effect of Delapril, a lipophilic ACE-I, on the development of atherosclerosis in cholesterol-fed rabbits. While it did not correct hyperlipidemia, Delapril dose dependently inhibited the development of atherosclerosis, expressed as aortic area covered by lesions (23.3+/-4.1, 21.3+/-2.4 and 18.5+/-3.3% with Delapril at the daily dose of 5, 10 and 20 mg/kg, respectively, versus 38.2%+/-6.4 for control animals) and its effect was similar to that of Captopril (14.5+/-5.1% at the daily dose of 25 mg/kg). Furthermore, Delapril partially and dose dependently restored endothelium-dependent relaxation, which is impaired in vessels from hypercholesterolemic animals (51.80+/-12.18, 59.74+/-5.16, 69.13+/-8.70 maximal percent relaxation versus 48.26+/-3.05% for the untreated control and 67.67+/-6.72% for Captopril-treated animals). An antioxidant mechanism is unlikely to explain this data, since Delapril does not contain thiol groups. These observations suggest that Delapril may represent an effective pharmacological approach for the treatment of atherosclerosis during its early phases.

Rapid, low-technology MIC determination with clinical Mycobacterium tuberculosis isolates by using the microplate Alamar Blue assay

A colorimetric, microplate-based Alamar Blue assay (MABA) method was used to determine the MICs of isoniazid (INH), rifampin, streptomycin (SM), and ethambutol (EMB) for 34 Peruvian Mycobacterium tuberculosis isolates (including both pansensitive and multidrug-resistant strains) and the H37Rv strain by using bacterial suspensions prepared directly from solid media. Results for all isolates were available within 8 days. Discordant results were observed on initial tests for 3 of 16 INH-susceptible isolates, 5 of 31 EMB-susceptible isolates, and 2 of 4 SM-resistant isolates (by the BACTEC 460 system). The overall agreements between the MICs obtained by MABA and the results obtained with the BACTEC 460 system were 87.9% for initial results and 93.6% after retesting 12 of 17 samples with discrepant results. Interpretation of MABA endpoints improved with technical experience. The MABA is a simple, rapid, low-cost, appropriate technology which does not require expensive instrumentation and which makes use of a nontoxic, temperature-stable reagent.

Susceptibility of Lutzomyia longipalpis (Diptera: Psychodidae) to selected insecticides in an endemic focus of visceral leishmaniasis in Venezuela

A field population of Lutzomyia longipalpis from La Rinconada, Lara State, an endemic focus of visceral leishmaniasis in Venezuela, was tested for susceptibility to organochlorine (DDT 2%), carbamate (propoxur 0.01%), organophosphate (malathion 2%, fenitrothion 1%, and pirimiphos methyl 1%), and pyrethroid (deltamethrin 0.06%, lambdacyhalothrin 0.06%, and permethrin 0.2%) insecticides. Susceptibility to the insecticides tested was evaluated in the field population of L. longipalpis and compared with a laboratory reference strain. The (LT95) to propoxur and malathion insecticides for the field population was lower than the LT95 for the laboratory reference strain, demonstrating high susceptibility to these compounds. A low level of resistance at LT50 (< 3-fold) was found for fenitrothion, pirimiphos methyl, and permethrin insecticides, but no resistance was detected at LT95. No significant resistance at the LT50 and LT95 was detected for the pyrethroids deltamethrin and lambdacyhalothrin. The susceptibility levels of L. longipalpis to the insecticides tested are discussed in view of a future control program against endophilic vectors of leishmaniases based on the use of pesticides.