Advances in mycobacterial isocitrate lyase targeting and inhibitors.

Isocitrate lyase plays a key role for survival of Mycobacterium tuberculosis in the latent form during a chronic stage of infection. This enzyme is important for M. tuberculosis during steady stage growth when it converts isocitrate to succinate and glyoxylate. Then, the glyoxylate is condensed with acetyl-CoA to form malate by malate synthase. The carbon conserving glyoxylate pathway has not been observed in mammals; therefore, it has been determined as a potential drug target for discovery of a new antituberculosis agent. Novel active molecules should shorten the duration of therapy, prevent resistance development and eliminate latent disease. The review summarizes recent progresses in isocitrate lyase inhibitors, overviews structural analogues of several metabolic intermediates (3-nitropropionate, 3-bromopyruvate, itaconate, itaconic anhydride), peptide inhibitors, and recently developed inhibitors with various chemical structures. The largest inhibitory activity against isocitrate lyase (IC(50) of 0.10 ± 0.01 µM) and concomitantly a significant antimycobacterial activity has been presented by fluoroquinolone derivative 1-cyclopropyl-7-[3,5-dimethyl-4-(3-nitropropanoyl)piperazin-1-yl]-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid, which has incorporated 3-nitropropionyl group as one of the structural analogue of succinate, a metabolic intermediate.

Antiviral activity of substituted salicylanilides--a review.

Chemotherapy of viral infections is still challenging. Salicylanilides demonstrated a wide range of biological activities including antiviral potency and the review summarizes this field. Niclosamide was described to be able to affect coronaviruses. Some salicylanilides and salicylamides could inhibit HIV virus by targeting of HIV-1 integrase or reverse transcriptase. Hepatitis C virus is another virus, which could be potentially afflicted by salicylanilides on the level of two enzymes--NS3 protease and NS5B RNA polymerase. Nitazoxanide is a nitrothiazole derivative of salicylamide useful for the treatment of protozoal and bacterial infections with an extended range of antiviral activity and innovative mechanism of action, especially against hepatitis and influenza viruses or rotaviruses. Nitazoxanide, its metabolite tizoxanide and their derivatives are a very promising stream in the development of new antiviral compounds. In this review, we summarize the antiviral activity of structures containing salicylanilide and partly salicylamide moiety.

Isolation and characterization of dcw cluster from Streptomyces collinus producing kirromycin.

A 4.5-kb BamHI fragment of chromosomal DNA of Streptomyces collinus containing gene ftsZ was cloned and sequenced. Upstream of ftsZ are localized genes ftsQ, murG, and ftsW, and downstream is yfiH. Gene ftsA is not adjacent to ftsZ or other genes of the cloned fragment. Protein FtsZ was isolated and characterized with respect to its binding to GTP and GTPase activity. The binding of GTP to FtsZ was Ca(2+) or Mg(2+) dependent with an optimum at 10 mM. The rate of GTP hydrolysis by FtsZ was stimulated by KCl. The presence of Ca(2+) (3-5 mM) resulted in a significant increase of GTPase activity. Higher concentrations of Ca(2+) than 5 mM had an inhibitory effect on GTPase activity. These results indicate that divalent ions (Ca(2+) or Mg(2+)) can be involved in regulation of GTP binding and hydrolysis of FtsZ. The maximum level of FtsZ was detected in aerial mycelium when spiral loops and sporulation septa were formed. FtsZ is degraded after finishing sporulation septa.

Er:YAG and alexandrite laser radiation propagation in root canal and its effect on bacteria.

OBJECTIVE: The objective of this study was to compare the bactericidal effect of the Er:YAG (wavelength 2.94 microm) and the Alexandrite (wavelength 0.75 microm) laser radiation. The spreading laser energy in the surrounding hard dental tissues round the root canal was evaluated and the bactericidal effect of both these different laser wavelengths was analyzed. SUMMARY BACKGROUND DATA: The use of a laser to clean and shape the root canal space is the latest method used for cleaning of root canals. The interest in laser endodontics was concentrated on the possibility to extirpate the contents of the root canal, to sterilize and to "melt" the walls of the root canals. The previous reports were performed with CO2, excimer, argon, Nd:YAG, Ho:YAG, and Er:YAG lasers. METHODS: Er:YAG laser system (2.94 microm, energy 100 mJ or 300 mJ, repetition rate 1 Hz, 30 pulses) and alexandrite laser system (0.75 microm, energy 250 mJ, repetition rate 1 Hz, 30 pulses) were prepared and three experimental arrangements were used during the measurements. First the energy transport through the tooth tissue was observed (frontal and side experimental setups) and then, the bactericidal effect was evaluated. RESULTS: It was demonstrated that due to the absorption in the hydroxyapatite and water content in the dentin, the Er:YAG laser radiation is fully absorbed in the root canal wall. This direct influence of the radiation could be expected only close to the sapphire tip. It was found that the tissue, which was not directly affected by the laser radiation, cannot be disinfected by the subablative effect of Er:YAG laser radiation. In the second part of the experiment the real bactericidal effect of Er:YAG ablative energy (300 mJ) could be observed. It was also shown that the alexandrite laser radiation with a wavelength of 0.75 microm spreads through the canal system space and leaks into the surrounding tooth tissues. Both lasers have bactericidal effect. CONCLUSIONS: The pulsed Er:YAG and alexandrite lasers can be efficiently used for killing dental bacteria but the spreading of their radiation in the tooth tissues are different.

[Local immune defects--products of free oxygen radicals]. / Lokálne imunodefekty--produkty volných kyslíkových radikálov.

The discussion about the supporting task of four main active oxygen dependent mechanisms mediating and modulating immune signals was included in the work, along with the discussion on antioxidants influencing these mechanisms. The former include xanthine-oxidase, cyclooxygenase, lipoxygenase, aldehyde oxygenase metabolic chains. Currently, we are just beginning to realize that active oxygen and antioxidants can modulate the induction of physiological signals, and that these effects are not limited to the immune system. The effects of antioxidant treatment could represent neutralization of harmful radicals, albeit they can simply represent modulation of complex biochemical events which are essential parts of normal metabolism. Some natural antioxidants, e.g. alfa-to-copherol, ascorbic acid and beta-carotens are very good means of the primary prevention, but with acute failure of local antioxidants, they do not prevent the excessive production of proliferative inflammatory tissue. Tirilazad-mesylate has threefold beneficial influences: first as an inhibitor of the creation of oxygen radicals, second as a scavenger or quencher of free oxygen radicals, and finally in the arrangement of the defects in the phospholipid bilayer and possible receptors of macrophages, as well as T cells. The drug is suitable for active modulation of locally changed immune reactions and thus it rejects harmful proliferative inflammation in the subdural space. Until recently it has been eliminated by surgical procedure. The authors expel the thick (0.8 cm) subdural collection of the proliferative inflammatory product by tandem treatment which includes methylprednisolon+tirilazad-mesylate for three days, followed by fourteen days of methylprednisolon, which was gradually decreased in daily oral doses. This is a revolutionary change in the treatment of similar intracranial processes. (Fig. 4, Ref. 21.)

[Single-photon emission-computed tomography in the diagnosis of cerebrovascular diseases]. / Príspevok jednofotónovej emisnej pocítacovej tomografie k diagnostike cievnych ochorení mozgu.

BACKGROUND: SPECT-HM-PAO allows to detect the regional cerebral blood flow and total diminution of the brain perfusion still before morphological substrate evolution in CT scan, without invasive technologies. SEARCH GOAL: The authors have analyzed data obtained by SPECT-99mTc HM-PAO in the group of 46 patients suffering from cerebrovascular disorders and they have compared them with results aimed by CT scans. Both, the SPECT-99mTc HM-PAO and CT scan were performed within 48 hours or later after the onset of the stroke; some of CT scans were repeatedly performed. RESULTS: They discovered 40 positive and 6 negative SPECT-HM-PAO findings, 26 positive and 20 negative CT scans. SPECT investigation more frequently discovers circulatory failures in the clinically altered hemisphere than the CT scan does in a substrate; SPECT discloses hypoperfusion of the clinically unaltered hemisphere if silent hypoperfusion is present. The ipsilateral foci of CT substrates were significantly less frequently observed (p < 0.001) than some ipsilateral regional hypoperfusions. Not only the number, but also size and extent of hypoperfusional foci searched by SPECT are significantly higher and wider than the numbers and dimensions of substrates observed by CT (p < 0.001). CONCLUSION: CT scan diagnostic possibilities are restricted by the time factor (CT examinations performed within 48 hours since the onset of the stroke are significantly less frequently positive than those performed later-p < 0.001). SPECT examination has not such a limiting time factor (p > 0.05). MEANING: Hence SPECT-HM-PAO renders early, long lasting and wide information on the restriction of the overall and regional perfusion, independently of the fact as to whether the reduction of cerebral perfusion is, or is not going to result in ischemic necrosis and/or ischemic sclerosis. SPECT renders correlation of the perfusion disorder earlier, wider in space, and more frequently than the CT scan, and therefore it is a prerequisite to the disclosure of the mentioned silent focal blood flow reductions. (Graph 12, Fig. 3, Ref. 4.)

[A new therapeutic approach in trophic defects of the lower extremities]. / Nový lécebný prístup u trofických defektu dolních koncetin.

The authors describe the case of a 60-year-old woman patient with a crural ulcer with a traumatic, arterial, venous and lymphatic aetiology. After three-year unsuccessful treatment by conventional methods and surgery a combination of hyperbaric oxygen therapy and plastic surgery was used. This rational therapeutic approach was very effective and the authors recommend its introduction into routine practice.

[Changes in hemostasis in persons exposed to a change in atmospheric pressure]. / Zmeny hemostázy u osob ve zmeneném atmosférickém tlaku.

In eight healthy volunteers--four professional and four amateur divers--in a hyperbaric chamber simulated diving was implemented, corresponding to the most frequently encountered conditions of diving activities in Czechoslovakia. Throughout the trial indicators of haemostasis were investigated. Under the selected model conditions changes of the investigated parameters developed which can be considered indicators of a latent process of disseminated coagulation and the so-called syndrome of silent bubbles.

[Treatment of ischemic cerebrovascular accidents with hyperbaric oxygenation]. / Lécba ischemických mozkových cévních príhod hyperbaroxií.

The authors present eleven year's experience with comprehensive treatment of patients who suffered an ischemic cerebrovascular attack. This comprises so-called conventional treatment of cerebrovascular attacks and also hyperbaroxia, i.e. administration of oxygen under high partial pressure. The authors used a therapeutic pressure of 0.2 MPa for 90 minutes in individual exposures. Of 31 treated patients 23 improved, i.e. 76%; eight improved slightly, eight significantly and seven substantially. The condition of the remainder did not change. Hyperbaroxia should therefore be used everywhere where this method is available.

[Sudden cerebrovascular accidents in the District of Martin. The clinical picture and epidemiologic data]. / Náhle cievne mozgové príhody v okrese Martin. Klinický obraz a epidemiologické údaje.

The authors investigated stroke morbidity (incidence, prevalence) and mortality, established register, and analyzed the epidemiological situation of this disease in the Martin district. Precondition for this study has been in 35 years neurological following the stroke patients at four neurological out-patients departments of the district and their hospitalization at the Neurological Clinic in Martin. During the period from 1983-1986 559 patients with an average age of 64.1 +/- 12.8 years (the range being 4-97 years) were treated at the above institutions. During four years of the study the average incidence of the stroke was 108/100.000/year. The mortality of the group 45/100.000/year is, as compared with world-wide statistics, low and is due to the care devoted to stroke patients for many years. The calculated, so-called expected prevalence, is 920 +/- 147/100.000 and can be explained by the relatively low mortality. In the Turiec region there are some 1012 +/- 162 stroke patients. This number was obtained by calculation for the number of inhabitants of the Martin District.

Enhancement of the Arthus reaction and suppression of delayed type hypersensitivity (DTH) by pluronic F-68, a detergent frequently used to prepare perfluorocarbon emulsions.

The effect of a 20% w/v RM101 (perfluorobutyltetrahydrofuran) emulsion containing 5% w/v of the detergent Pluronic F-68 or 5% w/v Pluronic F-68 given alone on the Arthus reaction and on delayed type hypersensitivity (DTH) were evaluated in female A/J mice. The test substances were administered i.v. at 1% body weight at 0,4,7,14 and 28 days prior to the i.p. immunization with 10(7) sheep red blood cells (SRBC). The increase in footpad swelling at 4 h (Arthus reaction) and at 24 h (DTH) after elicitation with the s.c. administration of 10(8) SRBC into the left footpad was used to assess immune competence. Pluronic F-68 given alone enhanced the Arthus reaction only when administered on day 0 of immunization. Pluronic F-68 given alone, as well as the perfluorocarbon emulsion containing Pluronic F-68, suppressed the 24 h DTH for as long as 4 days prior to immunization. Nonemulsified perfluorocarbon, on the other hand, had no effect on either the Arthus reaction or on DTH. The immunostimulatory agent, levamisole, administered (10 mg/kg i.p.) 1.5-2 h prior to immunization with SRBC counteracted both the Arthus reaction and the DTH response produced by Pluronic F-68. The present data clearly demonstrate that the changes in Arthus reaction and the DTH response are due to the Pluronic F-68 used to emulsify the RM101 perfluorocarbon; the changes induced by the detergent in these two immune parameters probably involve separate mechanisms.

Protective effects of trifluralin on benzo(a)pyrene-induced tumors in A/J mice.

Trifluralin, a widely used herbicide, added to the diet before the p.o. administration of benzo(a)pyrene (BP) and fed continuously, significantly inhibited the induction of lung and forestomach tumors in female A/J mice. Dietary intake of trifluralin before the administration of BP resulted in a significant increase in glutathione in lung and forestomach but not in liver and glandular stomach. Trifluralin treatment also inhibited the binding of [3H]BP to liver and lung DNA, as well as to protein in the liver. Under these conditions, the protection against BP-induced lung tumors and perhaps forestomach tumors may be due to an elevation of tissue glutathione, resulting in a decreased binding of reactive metabolites of BP to macromolecules at these sites. The results indicate that trifluralin has a "blocking" effect in its inhibition of BP-induced tumors. Our studies show that trifluralin also inhibits chemical carcinogenesis in lung and forestomach when started in the diet 1 day after the administration of BP and fed continuously thereafter. In the case of lung, although maximum inhibition of tumors occurred when trifluralin was started 1 day after BP, there was significant protection at all time intervals (0 to 7 days) against lung tumors. The finding that trifluralin protects against BP tumorigenesis when started in the diet after the administration of the carcinogen clearly demonstrates that trifluralin also has a "suppressive" effect against BP-induced tumors.

[Severe peripartum acidosis of the mature newborn infant (umbilical artery pH less than or equal to 7.00)--early morbidity and early growth]. / Schwere peripartale Azidose des reifen Neugeborenen (NApH less than or equal to 7,00)--Frühmorbidität und frühe Entwicklung.

Early morbidity and neurological development in 40 term infants with UApH less than or equal to 7,00 (6,60-7,00) were investigated. Group 1: 18 infants (45%) responded well to the measures of primary resuscitation--they never revealed any neurological symptoms and their growth and development were normal. Group 2: 15 infants (37,5%) who responded less well to primary resuscitation initially had mild to moderate neurological symptoms subsiding during the first few days of life. There were 2 cases of necrotizing enterocolitis and 4 cases of moderate meconium aspiration syndrome. Apgar scores, pH and blood-gases were worse than in group 1. At discharge and on follow-up all children appeared clinically normal. Group 3: 7 infants (17,5%) with severe neurological signs were not responding well to resuscitation. They were referred to the intensive care nursery and treated for cerebral edema (hyperventilation, pentobarbital, steroids). 2 infants with severe meconium aspiration syndrome recovered entirely. Two children had evidence of cerebral involvement as demonstrated by means of computerized tomography of the head, but were normal on follow-up. Three children with distinct signs of cerebral palsy developed cerebral atrophy and microcephaly, presumably due to hypoxic-ischemic encephalopathy. Early morbidity, comprising all 22 infants from group 2 and 3 amounts to 55%, morbidity up to an average age of 14,7 month includes 5 infants from group 3 (suspected cerebral lesions in 2, microcephalus in 3) and thus comes to 12,5% of the total.