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Persistent mitochondrial dysfunction and perinatal exposure to antiretroviral nucleoside analogues.

BACKGROUND: Zidovudine is commonly administered during pregnancy to prevent mother-to-child HIV-1 transmission. We investigated mitochondrial toxic effects in children exposed to zidovudine in utero and after birth. METHODS: We analysed observations of a trial of tolerance of combined zidovudine and lamivudine and preliminary results of a continuing retrospective analysis of clinical and biological symptoms of mitochondrial dysfunction in children born to HIV-1-infected women in France. Mitochondrial dysfunction was studied by spectrophotometry and polarography of respiratory-chain complexes in various tissues. FINDINGS: Eight children had mitochondrial dysfunction. Five, of whom two died, presented with delayed neurological symptoms and three were symptom-free but had severe biological or neurological abnormalities. Four of these children had been exposed to combined zidovudine and lamivudine, and four to zidovudine alone. No child was infected with HIV-1. All children had abnormally low absolute or relative activities of respiratory-chain complexes I, IV, or both months or years after the end of antiretroviral treatment. No mutation currently associated with constitutional disease was detected in any patient. INTERPRETATION: Our findings support the hypothesis of a link between mitochondrial dysfunction and the perinatal administration of prophylactic nucleoside analogues. Current recommendations for zidovudine monotherapy should however be maintained. Further assessment of the toxic effects of these drugs is required.

Acidosis, Lactic↗

Effects of water-borne copper on metallothionein and lipid peroxidation in the marine amphipod Gammarus locusta.

The aim of the current work was to determine over 10 days the effects of water-borne exposure of the marine amphipod Gammarus locusta to 4 microgCu l(-1) on the metallothionein (MT; measured by differential pulse polarography) protection system and lipid peroxidation (LP: thiobarbituric acid-reactive malondialdehyde equivalents) as a measure of oxidative damage. MT levels in exposed animals increased significantly at day 2 (36% > control; P < 0.001) and remained high at days 6 and 10 (55 and 38%, respectively, P < 0.001). The maximum level of MT at day 6 coincided with the highest Cu body-burden. LP increased within I day of exposure, indicative of Cu as an oxidative stressor. However, in contrast to MT, the highest LP level was seen at day 4 (68% > control, P < 0.001) before returning to control values by day 6, indicating a protective role of MT against the pro-oxidant effects of Cu.

Amphipoda↗

Evaluating environmental contamination in Ria Formosa (Portugal) using stress indexes of Spartina maritima.

Species of Spartina are potentially useful for biomonitoring coastal systems because they are abundant in the intertidal and have a wide geographic distribution in temperate zones. In this study, three indexes of physiological stress, thiolic protein concentration, adenylic energy charge (AEC) index [AEC = ATP + 0.5ADP/(ATP + ADP + AMP)] and photosynthetic efficiency (Fv/Fm), are measured in Spartina maritima plants collected at four sites and compared with metal concentrations in the sediments and Spartina tissues. Two sites were close to urban centers and two were located further away, in less contaminated areas. Concentrations of copper, cadmium, lead and zinc were determined by atomic absorption spectrophotometry, thiolic proteins were determined by polarography and adenilic nucleotides were determined by high performance liquid chromatography. Photosynthetic efficiencies were measured with a fluorometer. The sediments of sites closer to urban centers had higher concentrations of metals than the sites located further away. Metal concentration within plants did not follow this spatial pattern, probably due to spatial differences in metal bioavailability, uptake rates, internal transport and excretion processes. Concentrations of all metals studied were higher in underground plant structures than aerial, except cadmium whose levels were not significantly different. On the other hand, the stress indexes followed the spatial pattern of metals in the sediment. Thiolic protein concentrations were higher in plants from polluted sites, and were three to four times higher in aerial than in underground plant structures. Leaf AEC ratios and photosynthetic efficiencies were lower in plants from polluted sites indicating that they were growing under stressful conditions. We conclude that the use of these indexes in S. maritima represent a useful tool to monitor contamination in Ria Formosa lagoon as they provide an integrated measure of the toxicological burden of contamination.

Environmental Monitoring↗

Examination of in vivo influences on bioluminescent microbial assessment of corrosion product toxicity.

The composition of ionically dissolved and precipitated corrosion products from both free corrosion of ASTM F75 Co-Cr-Mo and galvanostatic polarization of Co-Cr-Mo and F138 316L stainless steel was determined using differential pulse polarography and inductively coupled plasma atomic emission spectroscopy. A bacterial bioluminescence assay, Microtox, was used to assess the toxicity of the solid and dissolved corrosion products produced by galvanostatic polarization and the individual ions within them. The role of in vivo salinity, temperature, and protein content as modulators of corrosion product toxicity assessment was investigated empirically and mechanistically. Co-Cr-Mo products were found to be more toxic than those of 316L, and the most toxic ions were Cr6+, Ni2+, and Co2+. Ringer's solution potentiated the toxicity of the more toxic metal ions and reduced the toxicity of the less toxic ions. Using theoretical analysis in conjunction with experimental measurements, the ions in both alloys were found to interact in an antagonistic fashion. The presence of albumin was found to decrease metal toxicity, presumably by chelation.

Albumins↗

Chemical and physical speciation of arsenic in a small pond receiving gold mine waste effluent.

The chemical and physical speciation of arsenic in a small pond that receives wastewater from a gold mine operation in western Victoria, Australia was studied using differential pulse polarography. By using different sample pretreatments, distinction between the physical states (dissolved or particulate As), between the oxidation states (As(III) or As(V)), and between the degrees of lability (labile or strongly bound) was achieved. The results are interpreted in terms of the physicochemical properties with reference to the use of the pond as a settlement dam for gold mining effluent. The speciation of arsenic was found to vary markedly with the physicochemical properties of the water. A model for the behavior of arsenic in the pond is proposed.

Animals↗

Release of NO by a nitrosyl complex upon activation by the mitochondrial reducing power.

The reaction of trans-[Ru(NH(3))(4)P(OEt)(3)NO](3+) and mitochondria was investigated through differential pulse polarography and fluorimetry. The nitrosyl complex undergoes one-electron reduction centered on the NO ligand site. The reaction between the mitochondrial reductor and trans-[Ru(NH(3))(4)P(OEt)(3)NO](3+) exhibits a second order specific rate constant calculated as k=2 x 10(1) M(-1) s(-1). The reduced species, trans-[Ru(NH(3))(4)P(OEt)(3)NO](2+), quickly releases NO, yielding trans-[Ru(NH(3))(4)P(OEt)(3)H(2)O](2+). The low toxicities of both trans-[Ru(NH(3))(4)P(OEt)(3)(NO)](2+) and trans-[Ru(NH(3))(4)P(OEt)(3)H(2)O](2+) and its ability to release NO after reductive activation in a biological medium make the nitrosyl compound a useful model of a hypotensive drug.

Animals↗

Metal-ion speciation in blood plasma incorporating the bisphosphonate, 1-hydroxy-4-aminopropilydenediphosphonate (APD), in therapeutic radiopharmaceuticals.

In the quest for more effective pain palliation radiopharmaceuticals for metastatic bone cancer, this paper relates results obtained with 166Ho complexed to the bone-seeking bisphosphonate, 1-hydroxy-4-aminopropililydenediphosphonate (APD). APD is itself a bone cancer pain palliation agent and this work was therefore driven by the idea that the energetic beta-particle emitter, 166Ho, coupled with APD could afford a highly effective radiopharmaceutical in the treatment of bone cancer. Complex-formation constants for important blood plasma metal-ions were measured by potentiometry or polarography at 37 degrees C and I = 150 mmol dm-3. The latter technique was used for systems where precipitates formed at ligand-to-metal ratios appropriate for potentiometry. For trivalent lanthanides, neither electrochemical technique could be used. Animal tests showed that the 166Ho-APD complex was taken up primarily by the liver due to precipitation or colloid formation.

Animals↗

Airborne lead in the Springfield, Missouri, area during a 19-year period (1975-1993).

Concentrations of airborne lead at Springfield, Missouri, in 1975-1993 have been determined by analysis of particulate material collected on glass-fiber filters during the 19-year period. Nitric acid-soluble lead in 1100 samples collected at a total of 19 monitoring stations was determined by atomic absorption spectroscopy and by differential pulse polarography. Ambient concentrations of airborne lead were found to decrease steadily (by more than 90%) during this period in spite of increases in area population and in automobile traffic. The decrease is significantly correlated with national trends in total emissions of lead to the atmosphere and with US ambient lead levels. Airborne lead from a coal-fired power plant was small compared with that from gasoline burning.

Journal Article↗

The induction of metallothionein in tissues of the Norway lobster Nephrops norvegicus following exposure to cadmium, copper and zinc: the relationships between metallothionein and the metals.

Nephrops norvegicus were exposed simultaneously to cadmium, copper and zinc over an 18-day period. Exposure concentrations were control, 1, 5 and 25 microg litre(-1) for cadmium and copper and 8, 40 and 200 microg litre(-1) for zinc. Concentrations of cadmium, copper, zinc and metallothionein were measured in homogenates of both the gill and the hepatopancreas. Quantification of metallothionein was carried out by differential pulse polarography. Cadmium concentrations increased significantly in the gill and hepatopancreas of both male and female animals in response to increases in exposure concentration. In contrast, the concentration of copper and zinc increased significantly in the gills of males, but not in females. In the hepatopancreas, neither copper nor zinc resulted in significant changes in concentrations of these metals. Metallothionein concentrations in the gill and hepatopancreas were increased significantly in relation to metal exposure in both males and females. Concentrations of cadmium and metallothionein in both the gill and hepatopancreas of males and females were positively correlated. Copper in the hepatopancreas also showed positive relationships with MT concentrations in males, but not in females. This study suggested that cadmium MTs in the gill and hepatopancreas of Nephrops norvegicus could be used as a sensitive tool to detect cadmium contamination in the lobsters, although this was not true for copper and zinc.

Journal Article↗

Effect of zenarestat, an aldose reductase inhibitor, on endoneurial blood flow in experimental diabetic neuropathy of rat.

The effects of zenarestat, an aldose reductase inhibitor, on endoneurial blood flow (NBF) were explored in streptozotocin-induced diabetic rats. Rats were maintained on a diet of containing 0.09% zenarestat for 8 weeks, then NBF in the sciatic nerve was measured using microelectrode hydrogen polarography. NBF in the diabetic control rats was significantly lower than values in age-matched control rats, however, NBF was not significantly altered in diabetic rats treated with zenarestat. Direct application of nitric oxide synthase inhibitor, NG-nitro-L-arginine, did not affect NBF in diabetic control rats, whereas this application significantly reduced NBF both in age-matched control and zenarestat treated diabetic rats. Considerable levels of zenarestat were confirmed in the sciatic nerve in the drug treated rats. These data suggest that aldose reductase, such as zenarestat, might restore or prevent the alteration of endoneurial blood flow resulting from an impairment of nitric oxide function.

Aldehyde Reductase↗

Local sensory ganglion ischemia induced by endothelin vasoconstriction: vulnerability of diabetic neurons and microvessels.

In some disorders of the peripheral nervous system, it is relevant to understand how sensory neurons respond to selective ganglion ischemia. Sensory dorsal root ganglia may be susceptible to ischemic damage and irretrievable neuron loss because of their metabolic requirements. In diabetes, heightened sensitivity to ischemia associated with elevated endothelin levels might render ganglia particularly vulnerable. In this work, we created a model of local sensory ganglion ischemia by generating intense local vasoconstriction from applied endothelin-1 (ET). In this model, we compared relative vulnerability of L5 ganglia microvessels and neurons to ET in streptozotocin-induced diabetic rats and nondiabetic controls. Diabetic ganglia had reductions in baseline core ganglion blood flow (GBF) measured using microelectrode hydrogen clearance polarography and ET induced particularly profound declines. Serial GBF measurements made using a laser Doppler flowmetry probe also indicated that diabetic ganglia exposed to ET had a marked prolongation in its action. Neuron perikarya and proximal axon segments were more vulnerable in diabetes. Neurons exhibited loss of neurofilament labeling, dissolution of the neurons, replacement of neurons with "nests of Nageotte," displacement of nuclei to the periphery of perikarya, and nuclear labeling with TUNEL. Both intraganglionic axons and downstream sural sensory axons developed evidence of axonal degeneration. Local endothelin-induced vasoconstriction of microvessels supplying dorsal root ganglia provides a selective model of ischemia. Diabetic vessels and neurons, exposed to a greater depth and duration of ischemia from endothelin, are especially vulnerable.

Animals↗

Determination of chlordiazepoxide, diazepam, and their major metabolites in blood or plasma by spectrophotodensitometry.

An analytical procedure was developed for the determination of chlordiazepoxide, diazepam and their major metabolites in blood or plasma. Demoxepam, a metabolite of chlordiazepoxide, is determined by spectrofluorometry after extraction. The remaining compounds are determined by spectrophotodensitometry after thin-layer chromatographic separation. The sensitivity limit of the spectrofluorometric determination of demoxepam is 0.1 to 0.2 microgram while that of the spectrophotodensitometric determination of chlordiazepoxide, diazepam and their N-desmethyl metabolites is 0.05 to 0.2 microgram. The sensitivity and specificity of the assay renders it suitable for monitoring plasma levels of chlordiazepoxide and its major metabolites following single or chronic oral administration of chlordiazepoxide hydrochloride. The sensitivity limit for diazepam and nordiazepam, its major metabolite, renders the assay useful only for the determination of plasma concentrations resulting from high dosage of diazepam. The assay was used to determine chlordiazepoxide and its metabolites following oral administration of Librium. The data showed a significant correlation to those obtained on the same specimens by differential pulse polarography and by radioimmunoassay.

Chlordiazepoxide↗

Analysis of cystine in human blood for monitoring of cases of burns.

Various diseases cause abnormalities in the composition of blood and urine by increase or decrease of concentrations of its constituents or through the appearance of new compounds therein. The analysis of blood samples obtained from a healthy individual and burns patients, for its cystine contents has been done successfully using direct current poloragraphy (DCP), differential pulse polarography (DPP) and differential pulse anodic stripping voltammetry (DPASV). The observed data was analysed statistically. The standard deviation and coefficient of variance of the data proved high reliability and accuracy of the method. In Bredicka Cobaltous solution (0.001 M CoCl(2)+0.1 M NH(4)OH+0.1 M NH(4)Cl) at pH 8.5+/-0.02, cystine present in blood samples produces two step catalytic hydrogen reduction wave with peak potential (E(P)) values equal to -l.22 and -1.46 V vs SCE. The height of the second wave was found to be proportional to cystine concentration. Blood samples obtained from a healthy individual and those from cases of burns having different percentages (16, 13, 9 and 6%) were analysed. Monitoring of the recovery of a patient (burn case 58%) after different time intervals during the treatment period was also done, till the patient was relieved from the hospital. The method has proved to be convenient and less time consuming for the clinical purpose.

Burns↗

Voltammetric determination of josamycin (a macrolide antibiotic) in dosage forms and spiked human urine.

The voltammetric behaviour of josamycin (a macrolide antibiotic) has been studied using direct current (DC(t)) alternating current (AC(t)) and differential pulse polarography (DPP). In Britton-Robinson buffers, josamycin developed cathodic waves over the pH range 7-12. At pH 10, a well-defined cathodic wave with diffusion current constant of 1.06 +/- 0.19 (n = 5) was obtained. The wave was characterized as being diffusion-controlled; and partially affected by adsorption phenomenon. The current-concentrations plots are rectilinear over the range 10-60 and 6-50 microg/ml using DC(t) mode and DPP mode, respectively. The minimum detectability limit was 1.2 microg/ml (1.9 x 10(-6) M) adopting the DPP mode. A method was proposed for the determination of josamycin in its tablets adopting both DC(t) and DPP modes. The results obtained were in good agreement with those given by the manufacturer. The method was extended to the in-vitro determination of the drug in spiked human urine; the % recovery was 98.06 +/- 1.76% (n = 5). The number of electrons involved in the reduction process was accomplished and a proposal of the electrode reaction was presented.

Anti-Bacterial Agents↗

Stripping voltammetric and polarographic techniques for the determination of anti-fungal ketoconazole on the mercury electrode.

The electroanalytical behaviour of ketoconazole in Britton-Robinson buffer is described. The reduction process on the hanging mercury drop electrode (HMDE) gives rise to one peak over -1.6 V (vs. Ag/AgCl/sat.KCl), within the pH range studied (4.7-9.6). The results showed that the reduction of ketoconazole is irreversible and the limiting current is adsorption controlled. The dependence of the peak current on the concentration was studied by means of different polarographic and voltammetric techniques. Using adsorptive stripping differential pulse voltammetry (AdS-DPV), the detection limit (DL) reached was 5.3 x 10(-11) mol l(-1). Two procedures, based on differential pulse polarography (DPP) and AdS-DPV in aqueous medium were developed for the determination of ketoconazole in a gel formulation and spiked urine samples, respectively.

Antifungal Agents↗

Diabetes causes an early reduction in autonomic ganglion blood flow in rats.

Impaired blood flow to peripheral nerve trunks makes a major contribution to the neuropathic complications of diabetes mellitus. Comparatively little attention has been paid to perfusion abnormalities for the cell bodies of origin of the autonomic and sensory nerves, although they are severely affected in diabetic neuropathy. The aim was to examine the time course of changes in superior cervical ganglion (SCG) perfusion in streptozotocin-induced diabetic rats. Ganglion blood flow, measured by hydrogen clearance microelectrode polarography, was approximately 70 ml min(-1) 100 g(-1). One week of diabetes caused a 46% perfusion deficit, which was maintained (54%) over 24 weeks. Thus, an early, profound, and long-lived reduction in ganglion perfusion may deleteriously affect neural cell body function and could contribute to autonomic neuropathy.

Aging↗

Comparison of German St. John's wort products according to hyperforin and total hypericin content.

OBJECTIVES: To compare the hyperforin and hypericin content of currently available St. John's wort products and to determine their batch-to-batch reproducibility. DESIGN: Representative products were obtained either directly from the manufacturer or purchased from pharmacies in and around Frankfurt, Germany. For five batches from each of the eight manufacturers, 10 individual dosage forms (tablets or capsules) were analyzed for both hyperforin and hypericin content. SETTING: Laboratories of the Institute of Pharmaceutical Chemistry at Johann Wolfgang Goethe University, Frankfurt, Germany. PRODUCTS: Eight German St. John's wort products containing from 250 mg to 612 mg dry extract were studied. Three of these products are capsules, four are film-coated tablets, and one is a sugar-coated tablet. Two of the products (Jarsin 300 and Neuroplant 300) are also available in the United States. METHODS: Hyperforin concentrations were analyzed by high-performance liquid chromatography. Total hypericin concentrations were determined by polarography, an electrochemical method. Concentrations were compared among different batches of the same product and among products from different manufacturers. RESULTS: The products contained widely differing amounts of hypericin and hyperforin, even after correcting for differences in the amount of extract per dose. Some products demonstrated consistent concentrations of hyperforin and hypericin from batch to batch, others exhibited pronounced interbatch variability. CONCLUSION: The St. John's wort preparations studied exhibited large differences in hypericin and hyperforin content and are not interchangeable for the treatment of mild-to-moderate depression. Pharmacists should take this variability into account when counseling patients on the use of St. John's wort products.

Anti-Bacterial Agents↗

The effects of local cooling on canine spinal cord blood flow.

The internal spinal cord blood flow was measured in dogs at the site of local cooling using hydrogen polarography. Blood flow decreased to 50% of the normothermic values during cooling of the cord to a central temperature of 16 degrees Celsius. Upon cessation of cooling internal blood flow rapidly returned to normal values. Implications of this finding for the treatment of spinal cord injury are discussed.

Animals↗