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Proceedings of the National Academy of... Jun 2006Poly(ADP-ribose) polymerase-1 (PARP-1), when activated by DNA damage, promotes both cell death and inflammation. Here we report that PARP-1 enzymatic activity is...
Poly(ADP-ribose) polymerase-1 (PARP-1), when activated by DNA damage, promotes both cell death and inflammation. Here we report that PARP-1 enzymatic activity is directly inhibited by minocycline and other tetracycline derivatives that have previously been shown to have neuroprotective and anti-inflammatory actions. These agents were evaluated by using cortical neuron cultures in which PARP-1 activation was induced by the genotoxic agents N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or 3-morpholinosydnonimine (SIN-1). In both conditions, neuronal death was reduced by >80% either by 10 muM 3,4-dihydro-5-[4-(1-piperidinyl)butoxy]-1(2H)-isoquinolinone, an established PARP inhibitor, or by 100 nM minocycline. Neuronal NAD(+) depletion and poly(ADP-ribose) formation, which are biochemical markers of PARP-1 activation, were also blocked by 100 nM minocycline. A direct, competitive inhibition of PARP-1 by minocycline (K(i) = 13.8 +/- 1.5 nM) was confirmed by using recombinant PARP-1 in a cell-free assay. Comparison of several tetracycline derivatives showed a strong correlation (r(2) = 0.87) between potency as a PARP-1 inhibitor and potency as a neuroprotective agent during MNNG incubations, with the rank order of potency being minocycline > doxycycline > demeclocycline > chlortetracycline. These compounds are known to have other actions that could contribute their neuroprotective effects, but at far higher concentrations than shown here to inhibit PARP-1. The neuroprotective and antiinflammatory effects of minocycline and other tetracycline derivatives may be attributable to PARP-1 inhibition in some settings.
Topics: Animals; Apoptosis; Cells, Cultured; Dose-Response Relationship, Drug; Enzyme Inhibitors; Mice; Minocycline; Molecular Structure; Neurons; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Recombinant Proteins; Tetracycline
PubMed: 16769901
DOI: 10.1073/pnas.0600554103 -
Congestive Heart Failure (Greenwich,... 2006Hyponatremia as it occurs in the heart failure patient is a multifactorial process. The presence of hyponatremia in the heart failure patient correlates with both the... (Review)
Review
Hyponatremia as it occurs in the heart failure patient is a multifactorial process. The presence of hyponatremia in the heart failure patient correlates with both the severity of the disease and its ultimate outcome. The therapeutic approach to the treatment of hyponatremia in heart failure has traditionally relied on attempts to improve cardiac function while at the same time limiting fluid intake. In more select circumstances, hypertonic saline, loop diuretics, and/or lithium or demeclocycline have been used. The latter two compounds act by retarding the antidiuretic effect of vasopressin but carry with their use the risk of serious renal and/or cardiovascular side effects. Alternatively, agents that selectively block the type 2 vasopressin receptor increase free water excretion without any of the adverse consequences of other therapies. Conivaptan, lixivaptan, and tolvaptan are three such aquaretic drugs. Vasopressin receptor antagonists will redefine the treatment of heart failure-related hyponatremia and may possibly evolve as adjunct therapies to loop diuretics in diuretic-resistant patients.
Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Diuretics; Heart Failure; Humans; Hyponatremia
PubMed: 16470095
DOI: 10.1111/j.1527-5299.2006.04844.x -
The Journal of Biological Chemistry Oct 2005Minocycline is a potent neuroprotective tetracycline in animal models of cerebral ischemia. We examined the protective properties of chlortetracycline (CTC) and...
Minocycline is a potent neuroprotective tetracycline in animal models of cerebral ischemia. We examined the protective properties of chlortetracycline (CTC) and demeclocycline (DMC) and showed that these two tetracyclines were also potent neuroprotective against glutamate-induced neuronal death in vitro and cerebral ischemia in vivo. However, CTC and DMC appeared to confer neuroprotection through a unique mechanism compared with minocycline. Rather than inhibiting microglial activation and caspase, CTC and DMC suppressed calpain activities. In addition, CTC and DMC only weakly antagonized N-methyl-D-aspartate (NMDA) receptor activities causing 16 and 14%, respectively, inhibition of NMDA-induced whole cell currents and partially blocked NMDA-induced Ca2+ influx, commonly regarded as the major trigger of neuronal death. In vitro and in vivo experiments demonstrated that the two compounds selectively inhibited the activities of calpain I and II activated following glutamate treatment and cerebral ischemia. In contrast, minocycline did not significantly inhibit calpain activity. Taken together, these results suggested that CTC and DMC provide neuroprotection through suppression of a rise in intracellular Ca2+ and inhibition of calpains.
Topics: Animals; Anti-Bacterial Agents; Brain Ischemia; Calcium; Calpain; Cell Culture Techniques; Chlortetracycline; Demeclocycline; Enzyme Inhibitors; Glutamic Acid; Mice; Mice, Inbred C57BL; Neurons; Neuroprotective Agents; Receptors, N-Methyl-D-Aspartate
PubMed: 16091365
DOI: 10.1074/jbc.M503113200 -
American Family Physician May 2004Hyponatremia is an important electrolyte abnormality with the potential for significant morbidity and mortality. Common causes include medications and the syndrome of... (Review)
Review
Hyponatremia is an important electrolyte abnormality with the potential for significant morbidity and mortality. Common causes include medications and the syndrome of inappropriate antidiuretic hormone (SIADH) secretion. Hyponatremia can be classified according to the volume status of the patient as hypovolemic, hypervolemic, or euvolemic. Hypervolemic hyponatremia may be caused by congestive heart failure, liver cirrhosis, and renal disease. Differentiating between euvolemia and hypovolemia can be clinically difficult, but a useful investigative aid is measurement of plasma osmolality. Hyponatremia with a high plasma osmolality is caused by hyperglycemia, while a normal plasma osmolality indicates pseudohyponatremia or the post-transurethral prostatic resection syndrome. The urinary sodium concentration helps in diagnosing patients with low plasma osmolality. High urinary sodium concentration in the presence of low plasma osmolality can be caused by renal disorders, endocrine deficiencies, reset osmostat syndrome, SIADH, and medications. Low urinary sodium concentration is caused by severe burns, gastrointestinal losses, and acute water overload. Management includes instituting immediate treatment in patients with acute severe hyponatremia because of the risk of cerebral edema and hyponatremic encephalopathy. In patients with chronic hyponatremia, fluid restriction is the mainstay of treatment, with demeclocycline therapy reserved for use in persistent cases. Rapid correction should be avoided to reduce the risk of central pontine myelinolysis. Loop diuretics are useful in managing edematous hyponatremic states and chronic SIADH. In all instances, identifying the cause of hyponatremia remains an integral part of the treatment plan.
Topics: Algorithms; Humans; Hyponatremia; Inappropriate ADH Syndrome; Osmolar Concentration; Water-Electrolyte Balance
PubMed: 15168958
DOI: No ID Found -
Nefrologia : Publicacion Oficial de La... 2002
Review
Topics: Animals; Antidiuretic Hormone Receptor Antagonists; Aquaporin 2; Aquaporin 6; Aquaporins; Ascites; Benzeneacetamides; Body Water; Demeclocycline; Diuresis; Diuretics; Humans; Kidney Tubules, Collecting; Liver Cirrhosis; Liver Cirrhosis, Experimental; Morpholines; Pyrrolidines; Rats; Receptors, Opioid, kappa; Receptors, Vasopressin; Spiro Compounds; Vasopressins
PubMed: 12107918
DOI: No ID Found -
Journal of Food Protection Jul 2000Performance of Tet-Lux, a newly developed microbiological test for the detection of tetracycline residues in raw milk, based on tetracycline-controlled luminescence... (Comparative Study)
Comparative Study
Qualitative detection of tetracycline residues in milk with a luminescence-based microbial method: the effect of milk composition and assay performance in relation to an immunoassay and a microbial inhibition assay.
Performance of Tet-Lux, a newly developed microbiological test for the detection of tetracycline residues in raw milk, based on tetracycline-controlled luminescence activation of the test bacteria, was evaluated in bovine milks with variable amounts of somatic cells, bacteria, fat, protein, and natural inhibitory compounds. The sensitivity of Tet-Lux was also compared to a commercially available tetracycline immunoassay (Snap, Idexx Laboratories Inc.) and to a microbial inhibition test (Delvotest SP, Gist-Brogades). There were slight differences in the luminescence signals between different milk samples, but no single factor could be pointed out to be responsible for them. There appeared to be a modest inverse relationship between luminescence and increasing fat and protein content. The amount of somatic cells, bacteria, and the natural inhibitors lysozyme and lactoferrin did not affect the luminescence response. The test fulfilled the sensitivity requirement specified by the European Union (maximum residue limit 100 ng/ml for tetracyclines). The Tet-Lux test was clearly more sensitive to all tetracyclines tested (oxytetracycline, tetracycline, chlortetracycline, doxycycline, demeclocycline, methacycline, minocycline) than Delvotest SP, and for five tetracyclines out of seven more sensitive than Snap. The test provides a fast, simple, and robust microbial method for the qualitative detection of tetracycline residues in milk.
Topics: Animals; Anti-Bacterial Agents; Biological Assay; Cattle; Dose-Response Relationship, Drug; Drug Residues; Enzyme-Linked Immunosorbent Assay; Escherichia coli; Immunoassay; Milk; Sensitivity and Specificity; Spectrometry, Fluorescence; Tetracycline
PubMed: 10914667
DOI: 10.4315/0362-028x-63.7.953 -
Applied and Environmental Microbiology Apr 2000The secondary metabolite 6-demethylchlortetracycline (6-DCT), which is produced by Streptomyces aureofaciens, is used as a precursor of semisynthetic tetracyclines....
The secondary metabolite 6-demethylchlortetracycline (6-DCT), which is produced by Streptomyces aureofaciens, is used as a precursor of semisynthetic tetracyclines. Strains that produce 6-DCT also produce a melanin-like pigment (MP). The correlation between MP production and 6-DCT production was investigated by using S. aureofaciens NRRL 3203. Production of both MP and 6-DCT was repressed by phosphate or ammonium ions, suggesting that syntheses of these compounds are controlled by the same regulators. Ten chlortetracycline-producing recombinants were derived from 6-DCT-producing mutant NRRL 3203 by gene replacement. All of the recombinants produced chlortetracycline but not MP, indicating that MP production is the results of a defect in the 6-methylation step and suggesting that the polyketide nonaketideamide is a common intermediate leading to MP as well as 6-DCT. To further examine the possibility that MP might be synthesized via the 6-DCT-biosynthetic pathway, mutants defective in 6-DCT biosynthesis were derived from a 6-DCT producer. Some of these mutants were able to produce MP, while others, including mutants with mutations in the gene encoding anhydrotetracycline oxygenase, an enzyme catalyzing the penultimate step in the pathway, produced neither 6-DCT nor MP. Production of 6-DCT and production of MP were restored simultaneously by integrative transformation with the corresponding 6-DCT-biosynthetic genes, indicating that some of 6-DCT-biosynthetic enzymes are indispensable for MP production. These findings suggest that a defect in the 6-methylation step results in redirection of carbon flux from a certain intermediate in the 6-DCT-biosynthetic pathway to a shunt pathway and results in MP production.
Topics: Anti-Bacterial Agents; Culture Media; Demeclocycline; Gene Expression Regulation, Bacterial; Melanins; Methylation; Multigene Family; Mutation; Pigments, Biological; Plasmids; Recombination, Genetic; Streptomyces aureofaciens
PubMed: 10742218
DOI: 10.1128/AEM.66.4.1400-1404.2000 -
Endocrine Journal Apr 1999To clarify the characteristics of vasopressin (AVP) secretion in patients with the syndrome of inappropriate antidiuresis (SIAD) related to central nervous system...
To clarify the characteristics of vasopressin (AVP) secretion in patients with the syndrome of inappropriate antidiuresis (SIAD) related to central nervous system disorders, we examined the response of AVP secretion to osmotic stimulus by hypertonic saline infusion and analyzed the possible causative factors in six patients with SIAD associated with head trauma or cerebral infarction. Hyponatremia developed after head trauma in four patients and cerebral infarction in two patients. In all patients the clinical state and laboratory findings fulfilled the criteria for SIAD, which was supported by either nonsuppressible plasma AVP levels or effectiveness of treatments with water restriction, demeclocycline, nonpeptide V2 AVP antagonist or diphenylhydantoin. Although patterns of plasma AVP response to the osmotic stimulus varied, plasma AVP concentrations neither increased nor decreased to undetectable levels with a rise in plasma osmolality. In one patient, plasma AVP levels responded to increasing plasma osmolality when plasma osmolality normalized; in which the threshold and the sensitivity of osmostat were normal. In two other patients, AVP secretion responded to plasma osmolality after the treatment. The changes in AVP secretion were not due to nonosmotic stimuli for AVP release. In conclusion, this study shows that patients with SIAD and central nervous system disorders may have persistent AVP secretion with a loss of hypotonic suppression such as found in patients with adrenal insufficiency or depletional hyponatremia in central nervous system disorders, indicating that careful evaluation is necessary to determine the relationship between persistent AVP secretion and the pathogenesis of hyponatremic disorders.
Topics: Aged; Arginine Vasopressin; Cerebral Infarction; Craniocerebral Trauma; Demeclocycline; Female; Follow-Up Studies; Hormone Antagonists; Humans; Hyponatremia; Inappropriate ADH Syndrome; Male; Middle Aged; Phenytoin; Saline Solution, Hypertonic; Water Deprivation; Water-Electrolyte Balance
PubMed: 10460011
DOI: 10.1507/endocrj.46.269 -
Journal of Food Protection May 1999Raw milk samples collected from bulk milk tankers may be screened for the presence of tetracycline antibiotics using rapid screening tests. If tetracycline residues are...
Raw milk samples collected from bulk milk tankers may be screened for the presence of tetracycline antibiotics using rapid screening tests. If tetracycline residues are detected, the milk may be shipped to a laboratory for high-pressure liquid chromatography (HPLC) analysis. Because the milk may be shipped on ice blocks, it is important to know whether tetracycline residues are stable at that temperature and for how long. Control raw milk samples fortified with 50 ppb each chlortetracycline, demeclocycline, methacycline hydrochloride, minocycline, oxytetracycline, and tetracycline were incubated at 4 degrees C or 25 degrees C, then analyzed using a metal chelate affinity chromatography extraction and HPLC. No loss of tetracycline was observed after 48 h of storage at 4 degrees C or 24 h at 25 degrees C. Losses ranging from 4 to 13% and 0 to 18% were noted after 72 h at 4 degrees C and 48 h at 25 degrees C, respectively.
Topics: Animals; Anti-Bacterial Agents; Chromatography, High Pressure Liquid; Drug Residues; Drug Stability; Food Handling; Milk; Reference Standards; Temperature; Tetracyclines
PubMed: 10340680
DOI: 10.4315/0362-028x-62.5.547 -
Bone May 1999Osteoporosis in men is a disease that is increasing in incidence, and with an increasing elderly population it poses a serious health problem. Since both testosterone...
Osteoporosis in men is a disease that is increasing in incidence, and with an increasing elderly population it poses a serious health problem. Since both testosterone (T) and growth hormone (GH) have an anabolic effect on bone and both decrease with aging, we were prompted to test whether the administration of these hormones in combination would increase bone mass in orchiectomized (orx) senile rats more than administration of either agent alone. Twenty-month-old male Wistar rats were divided into five groups with seven animals each: (a) age-matched intact control, (b) orx, (c) orx+GH (2.5 mg/kg/day), (d) orx+T [10 mg/kg, subcutaneous (s.c.), injection given twice a week], and (e) orx+GH+T. Testosterone and GH were given subcutaneously for 4 weeks. Bone histomorphometry of the tibial shaft showed that the orx group had lower cortical bone area than the intact control group. The decrease in cortical bone area was due to increased intracortical porosis as well as decreased periosteal bone formation rate (BFR). Administration of T to the orx animals prevented the development of the porosis and the decrease in periosteal BFR. The bone mineral content (BMC) and bone mineral density (BMD) of the femur as tested by dual-energy X-ray absorptiometry were significantly higher in the orx+T than in the orx group and were not significantly different from that of the intact control group. Administration of GH to the orx rats increased periosteal BFR significantly; however, the BMC and BMD measured were not increased significantly in comparison to the orx group. When GH and T were combined in treatment, the cortical bone area, periosteal BFR, and femoral BMD were all significantly higher than that of the orx and even higher than the intact control rats. Two-way analysis of variance shows that the individual effect of GH and T treatment on the periosteal BFR and cortical bone area was significant. The effect of T, but not GH, on femoral BMC and BMD was also significant; however, there is no synergistic interaction between the two treatments. Four weeks of orx with or without GH or T administration had no significant effect on tibial metaphyseal cancellous bone volume. In conclusion, this short-term study suggests that the combined intervention of GH and T in androgen-deficient aged male rats may have an independent effect in preventing osteopenia. The significant effect of GH+T may be attributed to the prevention of intracortical porosis, and an increase in periosteal bone formation and cortical bone mass.
Topics: Absorptiometry, Photon; Aging; Animals; Body Weight; Bone Density; Bone Development; Demeclocycline; Drug Synergism; Femur; Human Growth Hormone; Humans; Male; Orchiectomy; Rats; Rats, Wistar; Testosterone
PubMed: 10321909
DOI: 10.1016/s8756-3282(99)00018-6