Metabolic resistance to deltamethrin is mediated by P450 and esterases in common bed bugs Cimex lectularius L. (Heteroptera: Cimicidae)

The infestations of Cimex lectularius L. (Heteroptera: Cimicidae) registered in the last decades have been influenced by several human activities, including international tourism and commerce. Moreover, the development of insecticide resistance and careless pest control strategies contributed to the dispersal of bed bugs. Given the complexity of the topic, distinguishing physiological and molecular mechanisms involved in resistance can help design proper control tools and limit the resistance spread. Here we determined the susceptibility to deltamethrin and imidacloprid in bed bugs collected in Italy. Also, we assessed the role of esterases and P450 monooxygenases by direct enzymatic activity measurement and inhibition by synergism bioassays. Our results showed that the field-collected colony exhibited high resistance ratios to imidacloprid and deltamethrin (757 and >60,000 times, respectively) compared to the susceptible colony. Moreover, resistant bed bugs showed increased activity of esterases and P450 monooxygenases. The synergistic effect of piperonyl butoxide (PBO) suggests the significant contribution of both enzymatic groups as detoxification pathways implicated in pyrethroid-resistant bed bugs. Further investigations are needed to unravel the biochemical and molecular basis involved in the resistant phenotype for developing novel strategies for pest control.

Priming of Defense Systems and Upregulation of MYC2 and JAZ1 Genes after Botrytis cinerea Inoculation in Methyl Jasmonate-Treated Strawberry Fruits

Several attempts have been made to study the effects of methyl jasmonate (MeJA) on plants in the past years. However, the comparative effects of the number and phenological time of MeJA applications on the activation of defense systems is currently unknown in strawberries. In the present research, we performed three field treatments during strawberry (Fragaria× ananassa 'Camarosa') fruit development and ripening which consisted of differential MeJA applications at flowering (M3), and the large green (M2 and M3) and red ripe (M1, M2, and M3) fruit stages. We also checked changes in gene expression related to plant defense against Botrytis cinerea inoculation post-harvest. In M3 treatment, we observed an upregulation of the anthocyanin and lignin contents and the defense-related genes, encoding for chitinases, β-1,3-glucanases and polygalacturonase-inhibiting proteins, after harvest (0 hpi), along with the jasmonate signaling-related genes FaMYC2 and FaJAZ1 at 48 h after B. cinerea inoculation (48 hpi) during postharvest storage. Although we did not find differences in gray mold incidence between the MeJA treatments and control, these results suggest that preharvest MeJA treatment from the flowering stage onwards (M3) primes defense responses mediated by the upregulation of different defense-related genes and retains the upregulation of MYC2 and JAZ1 at 48 hpi.

An overview of environmental arsenic issues and exposure risks in Uruguay

Evidence for low-dose health effects of Arsenic (As) in humans is still controversial and presents a major public health issue in several countries worldwide. It is not clear yet, whether there is a lower safe threshold for arsenic in drinking water among other possible sources such as food, below which, exposures are not harmful. In Uruguay, safe drinking water is supplied to 94% of the population by a state company (OSE) and As levels in workplaces and food are officially regulated. This paper aims to present and discuss the issues regarding arsenic exposure risks to the environment and human population, which are being addressed in a multidisciplinary manner in Uruguay since 2007. An overview is given on both the background and the current situation, presenting reports and research studies conducted on these problems by various academic, state, and private institutions that deal with regulations, surveillance, and health care. Scientific research on geogenic As levels in groundwater indicates As levels above those recommended by the WHO for drinking water (10 μg L^-1) in different Uruguayan aquifers. There is a lack of baseline studies concerning Uruguayan residents that are exposed to As in drinking water over time. Furthermore, there is a need for data on environmental chemical exposure that could be associated with disease or death in the country. In addition, only a few As risk exposure assessment studies in children, adults, and workers using biomarkers in urine are available. Furthermore, this paper presents As levels in a rice growing region and the spatial distribution of groundwater arsenic data compared to a national cancer atlas database as ongoing research advances. Multidisciplinary research projects and local future actions are also described. This contribution constitutes a first attempt to develop a feasible health risk assessment of low-dose arsenic exposure in this Latin-American country.

Long-term effectiveness of irreversible electroporation in a murine model of colorectal liver metastasis

Irreversible electroporation (IRE) has recently gained in popularity as an ablative technique, however little is known about its oncological long-term outcomes. To determine the long-time survival of animals treated with a high dose of IRE and which histological changes it induces in tumoral tissue, IRE ablation was performed in forty-six athymic-nude mice with KM12C tumors implanted in the liver by applying electric current with different voltages (2000 V/cm, 1000 V/cm). The tumors were allowed to continue to grow until the animals reached the end-point criteria. Histology was harvested and the extent of tumor necrosis was semi-quantitatively assessed. IRE treatment with the 2000 V/cm protocol significantly prolonged median mouse survival from 74.3 ± 6.9 days in the sham group to 112.5 ± 15.2 days in the 2000 V/cm group. No differences were observed between the mean survival of the 1000 V/cm and the sham group (83.2 ± 16.4 days, p = 0.62). Histology revealed 63.05% ± 23.12 of tumor necrosis in animals of the 2000 V/cm group as compared to 17.50% ± 2.50 in the 1000 V/cm group and 25.6% ± 22.1 in the Sham group (p = 0.001). IRE prolonged the survival of animals treated with the highest electric field (2000 V/cm). The animals in this group showed significantly higher rate of tumoral necrosis.

Irreversible electroporation of the liver: is there a safe limit to the ablation volume?

Irreversible electroporation is a fast-growing liver ablation technique. Although safety has been well documented in small ablations, our aim is to assess its safety and feasibility when a large portion of liver is ablated. Eighty-seven mice were subjected to high voltage pulses directly delivered across parallel plate electrodes comprising around 40% of mouse liver. One group consisted in 55 athymic-nude, in which a tumor from the KM12C cell line was grown and the other thirty-two C57-Bl6 non-tumoral mice. Both groups were subsequently divided into subsets according to the delivered field strength (1000 V/cm, 2000 V/cm) and whether or not they received anti-hyperkalemia therapy. Early mortality (less than 24 hours post-IRE) in the 2000 V/cm group was observed and revealed considerably higher mean potassium levels. In contrast, the animals subjected to a 2000 V/cm field treated with the anti-hyperkalemia therapy had higher survival rates (OR = 0.1, 95%CI = 0.02–0.32, p < 0.001). Early mortality also depended on the electric field magnitude of the IRE protocol, as mice given 1000 V/cm survived longer than those given 2000 V/cm (OR = 4.7, 95%CI = 1.8–11.8, p = 0.001). Our findings suggest that ionic disturbances, mainly due to potassium alterations, should be warned and envisioned when large volume ablations are performed by IRE.

Cigarette smoke condensate inhibits collagen gel contraction and prostaglandin E2 production in human gingival fibroblasts

BACKGROUND

Granulation tissue remodeling and myofibroblastic differentiation are critically important events during wound healing. Tobacco smoking has a detrimental effect in gingival tissue repair. However, studies evaluating the effects of cigarette smoke on these events are lacking.

MATERIAL AND METHODS

We used gingival fibroblasts cultured within free-floating and restrained collagen gels to simulate the initial and final steps of the granulation tissue phase during tissue repair. Collagen gel contraction was stimulated with serum or transforming growth factor-β1. Cigarette smoke condensate (CSC) was used to evaluate the effects of tobacco smoke on gel contraction. Protein levels of alpha-smooth muscle actin, β1 integrin, matrix metalloproteinase-3 and connective tissue growth factor were evaluated through Western blot. Prostaglandin E(2) (PGE(2)) levels were determined through ELISA. Actin organization was evaluated through confocal microscopy.

RESULTS

CSC reduced collagen gel contraction induced by serum and transforming growth factor-β1 in restrained collagen gels. CSC also altered the development of actin stress fibers in fibroblasts cultured within restrained collagen gels. PGE(2) levels were strongly diminished by CSC in three-dimensional cell cultures. However, other proteins involved in granulation tissue remodeling and myofibroblastic differentiation such as alpha-smooth muscle actin, β1 integrin, matrix metalloproteinase-3 and connective tissue growth factor, were unmodified by CSC.

CONCLUSIONS

CSC may alter the capacity of gingival fibroblasts to remodel and contract a collagen matrix. Inhibition of PGE(2) production and alterations of actin stress fibers in these cells may impair proper tissue maturation during wound healing in smokers.

Gingival wound healing: an essential response disturbed by aging?

Gingival wound healing comprises a series of sequential responses that allow the closure of breaches in the masticatory mucosa. This process is of critical importance to prevent the invasion of microbes or other agents into tissues, avoiding the establishment of a chronic infection. Wound healing may also play an important role during cell and tissue reaction to long-term injury, as it may occur during inflammatory responses and cancer. Recent experimental data have shown that gingival wound healing is severely affected by the aging process. These defects may alter distinct phases of the wound-healing process, including epithelial migration, granulation tissue formation, and tissue remodeling. The cellular and molecular defects that may explain these deficiencies include several biological responses such as an increased inflammatory response, altered integrin signaling, reduced growth factor activity, decreased cell proliferation, diminished angiogenesis, reduced collagen synthesis, augmented collagen remodeling, and deterioration of the proliferative and differentiation potential of stem cells. In this review, we explore the cellular and molecular basis of these defects and their possible clinical implications.

Defective Wound-healing in Aging Gingival Tissue

Aging may negatively affect gingival wound-healing. However, little is known about the mechanisms underlying this phenomenon. The present study examined the cellular responses associated with gingival wound-healing in aging. Primary cultures of human gingival fibroblasts were obtained from healthy young and aged donors for the analysis of cell proliferation, cell invasion, myofibroblastic differentiation, and collagen gel remodeling. Serum from young and old rats was used to stimulate cell migration. Gingival repair was evaluated in Sprague-Dawley rats of different ages. Data were analyzed by the Mann-Whitney and Kruskal-Wallis tests, with a p value of .05. Fibroblasts from aged donors showed a significant decrease in cell proliferation, migration, Rac activation, and collagen remodeling when compared with young fibroblasts. Serum from young rats induced higher cell migration when compared with serum from old rats. After TGF-beta1 stimulation, both young and old fibroblasts demonstrated increased levels of alpha-SMA. However, alpha-SMA was incorporated into actin stress fibers in young but not in old fibroblasts. After 7 days of repair, a significant delay in gingival wound-healing was observed in old rats. The present study suggests that cell migration, myofibroblastic differentiation, collagen gel remodeling, and proliferation are decreased in aged fibroblasts. In addition, altered cell migration in wound-healing may be attributable not only to cellular defects but also to changes in serum factors associated with the senescence process.

Effects of cigarette smoke and nicotine on cell viability, migration and myofibroblastic differentiation

BACKGROUND AND OBJECTIVE

Several studies have analysed the role of nicotine as a prominent agent affecting wound repair in smokers. However, tobacco smoke contains several components that may alter gingival wound healing. The present study aimed to analyse the roles of cigarette smoke condensate (CSC) and nicotine on cell viability, cell migration/invasion and myofibroblastic differentiation using primary cultures of human gingival fibroblasts.

MATERIAL AND METHODS

To compare the effects of CSC and nicotine, gingival fibroblasts were stimulated with CSC (0.4–500 lg/mL) and the corresponding nicotine concentrations (0.025–32 lg/mL) present in research cigarettes (1R3F). Cell viability was evaluated through the MTS assay. Cell migration and invasion were assessed through scratch wound assays, collagen nested matrices and trans well migration. a-Smooth muscle actin production was evaluated by western blotting.

RESULTS

Cigarette smoke condensate at 50 lg/mL induced a moderate increase in cell viability, whereas the corresponding nicotine concentration (3.2 lg/mL) did not produce this response. Cigarette smoke condensate at 250 lg/mL, but not nicotine at 16 lg/mL (the corresponding nicotine concentration), induced cell death. Both nicotine and CSC stimulated cell migration (50 lg/mL CSC; 3.2 lg/mL nicotine). At 150 lg/mL, CSC inhibited cell migration; however, the corresponding concentration of nicotine (9.6 lg/mL), did not have this effect. Although both nicotine and CSC inhibited a-smooth muscle actin production, only the latter induced a statistically significant effect on this response.

CONCLUSION

Cigarette smoke condensate may stimulate cell survival and migration at low concentrations and inhibit these cell responses at higher levels of exposure. Moreover, CSC may interfere in myofibroblastic differentiation.These results show that cigarette smoke, but not nicotine, may significantly alter cell viability, cell migration and myofibroblastic differentiation in gingival mesenchymal cells.

Simvastatin alters fibroblastic cell responses involved in tissue repair

BACKGROUND AND OBJECTIVE

Statins have been used to control hypercholesterolemia. However, these drugs also exert pleiotropic effects that include the modulation of inflammation and cell signaling. The present study has analyzed the effects of simvastatin on several cell responses involved in tissue repair, including cell adhesion, cell migration and invasion, actin cytoskeleton remodeling and cell viability.

MATERIAL AND METHODS

Primary cultures of gingival fibroblasts were stimulated with simvastatin. Cell adhesion was evaluated using a colorimetric assay. Cell spreading was evaluated microscopically. Cell migration and invasion were assessed using a scratch wound-healing assay and a bicameral cell culture system, respectively. Changes in actin cytoskeleton and focal adhesion assembly were evaluated through immunofluorescence for actin, vinculin and active β1 integrin. Rac activation was evaluated by means of a pull-down assay. Cell viability was assessed using a colorimetric assay that determines mitochondrial functionality. Data analysis was performed using the Mann-Whitney U-test.

RESULTS

Simvastatin diminished cell adhesion and spreading over a fibronectin matrix. It also altered the closure of scratch wounds induced on cell monolayers and cell invasion through a Transwell system. Simvastatin-treated cells displayed an altered lamellipodia with poorly developed focal adhesion contacts and reduced levels of β1 integrin activation. During cell spreading, simvastatin diminished Rac activation.

CONCLUSION

The present study shows that simvastatin may alter cell migration by disrupting the cell signaling networks that regulate the actin cytoskeleton dynamics. This mechanism may affect the response of gingival mesenchymal cells during wound healing.

Triclosan inhibits tumor necrosis factor-alpha-stimulated urokinase production in human gingival fibroblasts

BACKGROUND AND OBJECTIVES

Destruction of the supporting periodontal tissues is mediated by the action of several proteolytic enzymes. Urokinase is a serine protease that plays a key role in connective tissue destruction through conversion of plasminogen into plasmin. The present study was conducted to evaluate the effect of triclosan on the production and activity of urokinase in cultured gingival fibroblasts.

MATERIAL AND METHODS

Urokinase production was studied in primary cultures of human gingival fibroblasts stimulated with tumor necrosis factor-alpha. Urokinase activity and production were evaluated using casein zymography and western blotting, respectively. Urokinase mRNA expression was evaluated using the reverse transcription-polymerase chain reaction. Triclosan was used to interfere with this stimulatory effect. The roles of different cell-signaling cascades involved in urokinase production were assessed through western blotting and immunofluorescence using several cell-signaling inhibitors.

RESULTS

Tumor necrosis factor-alpha was found to be a strong stimulus for urokinase production and triclosan was able to inhibit this response at the protein and mRNA levels. Triclosan was also able to inhibit conversion of plasminogen into plasmin. Tumor necrosis factor-alpha-stimulated urokinase production was shown to be dependent on the nuclear factor-kappaB and c-Jun N-terminal kinase signaling pathways. Triclosan inhibited c-Jun N-terminal kinase phosphorylation and c-Jun production.

CONCLUSIONS

Within the limits of this study, these results show that triclosan may inhibit urokinase production and plasminogen activation in gingival fibroblasts through modulation of the c-Jun N-terminal kinase signaling pathway.

Cigarette smoke condensate stimulates urokinase production through the generation of reactive oxygen species and activation of the mitogen activated protein kinase pathways in human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Tobacco smoking is a significant risk factor for periodontal disease. It has been suggested that smoking may alter connective tissue remodeling in the periodontium. In the present study, we investigated whether cigarette smoke condensate modulates the production of the serine protease urokinase in human gingival fibroblasts.

MATERIAL AND METHODS

Primary cultures of human gingival fibroblasts were stimulated with cigarette smoke condensate. Urokinase production was evaluated through casein zymography and western blotting. Plasmin activation was assessed by means of a radial diffusion assay. The roles of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and reactive oxygen species in cigarette smoke condensate-stimulated urokinase production were studied using distinct selective inhibitors (SP600125, PD98059, N-acetyl cysteine). Reactive oxygen species production was determined using a fluorometric assay. Activation of ERK and JNK pathways were evaluated using western blots.

RESULTS

In gingival fibroblasts, cigarette smoke condensate potently stimulated urokinase production and plasmin activation. Cigarette smoke condensate-stimulated urokinase production was dependent on the activity of ERK/JNK pathways and was inhibited by the reactive oxygen species scavenger, N-acetyl cysteine. Cigarette smoke condensate strongly stimulated ERK and JNK phosphorylation and the generation of reactive oxygen species.

CONCLUSION

Cigarette smoke condensate stimulates urokinase production and plasmin activation in gingival fibroblasts. Moreover, cigarette smoke condensate-stimulated urokinase production depends on both the activation of ERK/JNK pathways and on the generation of intracellular reactive oxygen species. These results show that cigarette smoke may alter connective tissue remodeling by inducing production of the urokinase-type plasminogen activator through specific signaling pathways.

A modified commercial scanner as an image plate for table-top optical applications

A reliable, accurate, and inexpensive optical detector for table-top applications is described here. Based on a commercial high resolution office scanner coupled to a projection plate, the detector offers a large image plate surface, allowing recording of sizeable images without systematic errors associated with coupling optics aberrations. Several tests on distance-dependent and steady interference patterns are presented and discussed. The extension to other types of optical measurements by substituting the projection plate is proposed.

n-pentanol at high pressures: Rotational isomerism in the liquid phase and the liquid-solid phase transition

The vibrational spectrum of liquids constituted of chain molecules is difficult to analyze because it may have contributions of different rotational isomers. In turn, with a proper vibrational assignment, this feature allows us to extract information about the effect of temperature or pressure on the molecular conformations in the liquid state. In this regard, the information on the vibrational spectrum in the solid phase greatly simplifies the vibrational analysis of the different rotational conformers existing in the liquid, as the molecules usually present all-trans conformations in the crystalline state. Here we report room-temperature Raman experiments on n-pentanol performed in a sapphire-anvil cell up to 3 GPa. A detailed analysis of the liquid-solid phase transition occurring at 1.3 GPa is provided. The analysis of the Raman spectrum in the solid phase allows the identification of the bands due to the different rotational isomers present in the liquid. The analysis of the spectral region corresponding to skeletal vibrations of the carbon chain (800-1200 cm(-1)) indicates that gauche conformers are promoted by the application of pressure. The analysis of the intensity ratio of those bands assigned to trans and gauge conformations is used to calculate the change in molecular volume ascribed to the trans-gauge isomerization process. We find a value similar to that found in n-alkanes, i.e., -0.88 cm(3) mol(-1). In addition, we find indication that pressure varies the proportions of the different gauge conformers. Thus, it appears that the GTTt to TGTt transition in the carbon chain is favored at high pressures. As expected, a smaller change in the molecular volume accompanies this conformation change.

Light-scattering study of vibrational relaxation in liquid xylenes

Brillouin spectra obtained in dynamic light-scattering experiments are reported for the three isomeric xylenes (ortho-, meta-, and paradimethylbenzenes) between 288 and 363 K. Limiting sound velocities and relaxation times, as obtained from the polarized spectra using the theory developed by Mountain [J. Res. Natl. Bur. Stand. 70A, 207 (1966)], reveal the existence of a relaxation process. Our results suggest that the relaxation process in liquid xylenes has a purely vibrational nature. Vibrational-translational energy exchanges in xylenes are analyzed in terms of available molecular models and compared to those previously obtained for toluene and benzene. The results presented here confirm the important role played by the molecular geometry in the vibrational relaxation process, as the relative arrangement of the methyl groups has significant effect in determining the relaxing vibrational modes.

Pressure tuning of the Fermi resonance in liquid methanol: Implications for the analysis of high-pressure vibrational spectroscopy experiments

It has been argued that pressure tuning allows for unambiguous assignment of the nonperturbed bands involved in the Fermi coupling of molecular systems in the condensed phase. Here we study the pressure evolution of the Fermi resonance occurring in liquid methanol between the symmetric methyl-stretch fundamental and the methyl-bending overtones. Our analysis is based on Raman experiments in both stretching and bending fundamental regions, which are used to evaluate the effect of pressure on accidental degeneracies occurring in the vibrational spectra of liquid methanol. We emphasize that the difference in frequency of the Fermi doublet constitutes the governing quantity to determine the condition at which the exact degeneracy of the unperturbed modes occurs. Analysis based on the intensity ratio of the Fermi doublet must be disregarded. We confirm the necessity of measuring the full vibrational spectrum under pressure in order to obtain the Fermi coupling parameters unambiguously and to give a correct assignment of the bands involved in the resonance phenomenon. We also analyze the possible occurrence of several simultaneous resonance effects using a multilevel perturbation model. This model provides an appropriate description of the frequencies observed in the experiments over the whole pressure range if we consider that the main resonance occurs between nu3 and 2nu10, in contrast to previous assignments. Our global analysis leads to some general rules concerning measurement and interpretation of high-pressure vibrational spectroscopy experiments.

Phase transitions and hindered rotation in dimethylacetylene at high pressures probed by Raman spectroscopy

We present Raman spectroscopy experiments in dimethylacetylene (DMA) using a sapphire anvil cell up to 4 GPa at room temperature. DMA presents phase transitions at 0.2 GPa (liquid to phase I) and 0.9 GPa, which have been characterized by changes in the Raman spectrum of the sample. At pressures above 2.6 GPa several bands split into two components, suggesting an additional phase transition. The Raman spectrum of the sample above 2.6 GPa is identical to that found for the monoclinic phase II (C2/m) at low temperatures, except for an additional splitting of the band assigned to the fourfold degenerated asymmetric methyl stretch. The global analysis of the Raman spectra suggests that the observed splitting is due to the loss of degeneracy of the methyl groups of the DMA molecule in phase II. According to the above interpretation, crystal phase II of DMA extends from 0.9 GPa to pressures close to 4 GPa. Between 0.9 and 2.6 GPa, the methyl groups of the DMA molecules rotate almost freely, but the rotation is hindered on further compression.

Corticolous species of Trichothelium (Ascomycota: Porinaceae)

A survey of corticolous crustose lichen collections in connection with the Flora Neotropica project revealed a number of undescribed species of Trichothelium. While a few typically foliicolous taxa may occasionally be found on bark, five species seem to be exclusively corticolous, all with a Trentepohlia photobiont. Three of them are new species: T. angustisporum, T. caudatum, and T. kalbii spp. nov. A key is provided to all five corticolous species, accompanied by data on their distribution and ecology. A considerable range extension is reported for T. horridulum, with new collections from Costa Rica and north-eastern Brazil.

Molecular characterization of two natural hotspots in the Drosophila buzzatii genome induced by transposon insertions

Transposable elements (TEs) have been implicated in the generation of genetic rearrangements, but their potential to mediate changes in the organization and architecture of host genomes could be even greater than previously thought. Here, we describe the naturally occurring structural and nucleotide variation around two TE insertions in the genome of Drosophila buzzatii. The studied regions correspond to the breakpoints of a widespread chromosomal inversion generated by ectopic recombination between oppositely oriented copies of a TE named Galileo. A detailed molecular analysis by Southern hybridization, PCR amplification, and DNA sequencing of 7.1 kb surrounding the inversion breakpoints in 39 D. buzzatii lines revealed an unprecedented degree of restructuring, consisting of 22 insertions of ten previously undescribed TEs, 13 deletions, 1 duplication, and 1 small inversion. All of these alterations occurred exclusively in inverted chromosomes and appear to have accumulated after the insertion of the Galileo elements, within or close to them. The nucleotide variation at the studied regions is six times lower in inverted than in noninverted chromosomes, suggesting that most of the observed changes originated in only 84,000 years. Galileo elements thus seemed to promote the transformation of these, otherwise normal, chromosomal regions in genetically unstable hotspots and highly efficient traps for transposon insertions. The particular features of two new Galileo copies found indicate that this TE belongs to the Foldback family. Together, our results strengthen the importance of TEs, and especially DNA transposons, as inducers of genome plasticity in evolution.

Molecular characterization of two natural hotspots in the Drosophila buzzatii genome induced by transposon insertions

Transposable elements (TEs) have been implicated in the generation of genetic rearrangements, but their potential to mediate changes in the organization and architecture of host genomes could be even greater than previously thought. Here, we describe the naturally occurring structural and nucleotide variation around two TE insertions in the genome of Drosophila buzzatii. The studied regions correspond to the breakpoints of a widespread chromosomal inversion generated by ectopic recombination between oppositely oriented copies of a TE named Galileo. A detailed molecular analysis by Southern hybridization, PCR amplification, and DNA sequencing of 7.1 kb surrounding the inversion breakpoints in 39 D. buzzatii lines revealed an unprecedented degree of restructuring, consisting of 22 insertions of ten previously undescribed TEs, 13 deletions, 1 duplication, and 1 small inversion. All of these alterations occurred exclusively in inverted chromosomes and appear to have accumulated after the insertion of the Galileo elements, within or close to them. The nucleotide variation at the studied regions is six times lower in inverted than in noninverted chromosomes, suggesting that most of the observed changes originated in only 84,000 years. Galileo elements thus seemed to promote the transformation of these, otherwise normal, chromosomal regions in genetically unstable hotspots and highly efficient traps for transposon insertions. The particular features of two new Galileo copies found indicate that this TE belongs to the Foldback family. Together, our results strengthen the importance of TEs, and especially DNA transposons, as inducers of genome plasticity in evolution.

Posteroventral pallidotomy in Parkinson's disease

OBJECTIVE

We analyse the clinical aspects, results and reliability of posteroventral pallidotomy (PVP) carried out as treatment for the principal symptoms and treatment induced complications in patients with Parkinson's disease (PD).

PATIENTS AND METHODS

Between August 1995 January 1998, 17 patients with PD were treated surgically, 13 patients with PVP. A pre- and post-surgical clinical evaluation was carried out. Riechert's Stereotactic System (MHT, Freiburg, Germany) was used. Ventriculography under stereotactic conditions was used in the PVP procedures, Laitinen's co-ordinates as anatomical target, and electrical stimulation for physiological determination. 3 4 radiofrequency lesions were made at 83 degrees C for 20". The mean age was 60 +/- 10.8 years, ages ranging from 45-79 years. 8 (60.5%) of the patients were male. The cardinal symptoms of the series were bradykinesia and rigidity. The duration of the illness ranged from 8.6 +/- 3.7 years with a range of 4-15 years. 7 (53.8%) presented with a duration of 10 years or more. 6 (46,2%) of the patients underwent left PVP, the remaining 7 (53.8%) right PVP. Only one patient received treatment with right PVP and ipsilateral thalamotomy in the same surgical procedure. The mean post-surgical follow up was 16 +/- 7 months, with a range of 2 to 26 months.

RESULTS

An up to date evaluation was carried out on all patients showing significant changes after PVP in UPDRS motor (P < 0.005), complete rigidity relief (P < 0.005), bradykinesia relief (P < 0.005) and complete tremor relief (P < 0.005). An important improvement in contralateral dyskinesia was noted after PVP. A subjective evaluation of the results showed excellent results in 4 (30.8%) patients, good in 6 (46.2%) and fair in 3 (23%). No significant correlation was found between age and duration of illness (P = 0.7). Two patients suffered slight side effects, one patient with worsening of hypophonia whilst the other suffered subjective visual impairment controlled by normal post operative ophthalmological examinations. There was no peri-operative mortality.

CONCLUSION

PVP is considered a safe and effective surgical method for the treatment of both the principal symptoms of PD and the complications of DOPA medication.

Antimicrobial susceptibility of anaerobic and aerobic bacteria isolated from patients with mixed infections in Nicaragua

The agar dilution method was used to test the activity of ampicillin, benzylpenicillin, cefoxitin, imipenem, clindamycin, metronidazole, chloramphenicol, gentamicin, methicillin and vancomycin against 241 anaerobic and 227 aerobic bacteria isolated from 136 patients with intraabdominal infections and 49 with nonintraabdominal infections. Beta-lactamase production was tested in all strains. Overall, imipenem, metronidazole and chloramphenicol were the most active antimicrobial agents against anaerobic bacteria followed by clindamycin. Only the Bacteroides fragilis group was shown to be less susceptible to clindamycin (MIC90 8 mg/l). Ampicillin and cefoxitin were the least active beta-lactam antibiotics against the most common isolated B. fragilis group strains (MIC(90) >1024 and 64 mg/l, respectively) and against Escherichia coli strains (MIC(90) >1024 and >1024 mg/l, respectively). Chloramphenicol showed low activity against the Gram-negative aerobic bacteria, while gentamicin had good activity against the aerobic bacteria tested, except for E. coli and Pseudomonas. Among the Gram-positive aerobic and anaerobic bacteria tested, Staphylococcus aureus was shown to be less susceptible to beta-lactam antibiotics (29&#37; were methicillin resistant). No vancomycin-resistant S. aureus strains were found. A good correlation between beta-lactamase production and beta-lactam resistance was observed.

Recombination rate predicts inversion size in Diptera

Most species of the Drosophila genus and other Diptera are polymorphic for paracentric inversions. A common observation is that successful inversions are of intermediate size. We test here the hypothesis that the selected property is the recombination length of inversions, not their physical length. If so, physical length of successful inversions should be negatively correlated with recombination rate across species. This prediction was tested by a comprehensive statistical analysis of inversion size and recombination map length in 12 Diptera species for which appropriate data are available. We found that (1) there is a wide variation in recombination map length among species; (2) physical length of successful inversions varies greatly among species and is inversely correlated with the species recombination map length; and (3) neither the among-species variation in inversion length nor the correlation are observed in unsuccessful inversions. The clear differences between successful and unsuccessful inversions point to natural selection as the most likely explanation for our results. Presumably the selective advantage of an inversion increases with its length, but so does its detrimental effect on fertility due to double crossovers. Our analysis provides the strongest and most extensive evidence in favor of the notion that the adaptive value of inversions stems from their effect on recombination.

Generation of a widespread Drosophila inversion by a transposable element

Although polymorphic inversions in Drosophila are very common, the origin of these chromosomal rearrangements is unclear. The breakpoints of the cosmopolitan inversion 2j of D. buzzatii were cloned and sequenced. Both breakpoints contain large insertions corresponding to a transposable element. It appears that the two pairs of target site duplications generated upon insertion were exchanged during the inversion event, and that the inversion arose by ectopic recombination between two copies of the transposon that were in opposite orientations. This is apparently the mechanism by which transposable elements generate natural inversions in Drosophila.

Generation of a widespread Drosophila inversion by a transposable element

Although polymorphic inversions in Drosophila are very common, the origin of these chromosomal rearrangements is unclear. The breakpoints of the cosmopolitan inversion 2j of D. buzzatii were cloned and sequenced. Both breakpoints contain large insertions corresponding to a transposable element. It appears that the two pairs of target site duplications generated upon insertion were exchanged during the inversion event, and that the inversion arose by ectopic recombination between two copies of the transposon that were in opposite orientations. This is apparently the mechanism by which transposable elements generate natural inversions in Drosophila.

Stereotactic neurosurgery in children and adolescents

Between March 1992 and January 1998, 100 stereotactic procedures were carried out in our Stereotactic Department. Of these, 24 were performed on patients under 18 years of age, 22 of them under a local anaesthetic and sedation. The ages of these patients ranged between 4 months and 18 years. The stereotactic procedures carried out were: 15 cerebral biopsies, 5 iodine-125 implants, 4 implantations of Rickham reservoirs with ventricular catheter, with additional holes to establish a connection between the cyst content and the ventricular system (internal drainage): 2 of these patients had arachnoidal cysts in the pineal region, 1 a thalamic neuroepithelial cyst and 1 a cystic craniopharyngioma, with excellent control of hydrocephalus. All cerebral biopsies were positive, including 3 in which brain stem tumours were detected. Of the 5 patients treated by brachytherapy, 4 had pilocytic astrocytomas and 1 an anaplastic astrocytoma. The sites of the tumours for which implants were used were the thalamus in 4 cases, and the basal ganglia (corpus striatum) in 1. In only 2 cases was there some transistory morbidity, and mortality was nil. The stereotactic procedures in this varied group were well tolerated, with low morbidity and mortality rates, which proves that this method is effective and safe for patients. It can also be used for the diagnosis of brain stem tumours. Midline cysts can also be treated by means of internal drainage with catheters (a minimally invasive form of surgery).

Comparative mapping of cosmids and gene clones from a 1.6 Mb chromosomal region of Drosophila melanogaster in three species of the distantly related subgenus Drosophila

The successful hybridization of cosmid clones from Drosophila melanogaster (Sophophora subgenus) to the salivary gland chromosomes of other species as distantly related as those in the Drosophila subgenus attests their great potential for unravelling genome evolution. We have carried out, using 28 cosmids and 13 gene clones, a study of the organization of the D. melanogaster 95A-96A chromosomal region in three Drosophila subgenus species: D. repleta, D. buzzattii and D. virilis. These clones were first used to built an accurate map of this 1.6 Mb region of D. melanogaster chromosome 3R (Muller's element E). Then, they were hybridized and mapped to the homologous chromosome 2 of the other three distantly related species. The studied region is disseminated over 13 different sites of chromosome 2 in the Drosophila subgenus species, which implies a minimum of 12 inversion breakpoints fixed between the two subgenera. Extrapolation to the entire chromosome gives 90 fixed inversions. The D. melanogaster Pp1-96A-Acr96Aa segment conserved in D. repleta and D. buzzatii is longer than previously thought and is also conserved in D. virilis. In addition, three other D. melanogaster segments conserved in the three Drosophila subgenus species were found. Finally, our data indicate significant statistical differences in the evolution rate of Muller's element E among lineages, a result that agrees well with the previous cytogenetic data.

Antimicrobial susceptibility of anaerobic bacteria from the intestinal microflora of healthy children and antimicrobial-treated children in Nicaragua

The objective of this study was to determine the antimicrobial susceptibility of anaerobic bacteria from the intestinal microflora of healthy children who had not been treated with antimicrobial agents since birth or at 1, 3, 6, 12, 18 and 24 months of age, as well as from children of the same ages treated with the most commonly used antimicrobial agents in Nicaragua. A total of 947 Bacteroides and 745 Clostridium strains were isolated from 67 healthy and 94 antimicrobial-treated children. The minimal inhibitory concentrations of ampicillin, cefoxitin, imipenem, clindamycin, metronidazole and chloramphenicol were determined by the agar dilution method. Detection of ss-lactamase was made by the nitrocefin assay. No bacterial strains resistant to imipenem, clindamycin, metronidazole or chloramphenicol were found. The susceptibility of Bacteroides species to ampicillin and cefoxitin isolated from antimicrobial-treated children decreased progressively as the children reached 24 months of age, from 88% to 78% and from 94% to 81%, respectively. All the Bacteroides strains isolated from the healthy children were 100% susceptible to cefoxitin when they were <=12 months and 92% susceptible after this age; the susceptibility of Bacteroides strains to ampicillin in these children was from 91% at 1 month to 86% at 24 months of age. All Clostridium strains were susceptible to ampicillin and cefoxitin. The ss-lactamase production was seen only in Bacteroides species. These data indicate that a rational use of antimicrobial agents is needed to avoid the development of resistance in anaerobic bacteria.

[Neuro-ophthalmological alternations in patients with pituitary adenomas and intrasellar arachnoidocele]

INTRODUCTION, MATERIAL AND METHODS: We studied 103 patients with hypophyseal tumors aged between 15 and 74, with a marked predominance of females. Results. Of these, 49 patients were diagnosed as having macroadenomas (47.5%), 27 with microadenomas (26.2%), 25 with arachnoidoceles (24.3%) and two with craniopharyngiomas (1.9%). Of the total there were 78.9% functioning tumors of which the commonest was prolactinoma.

CONCLUSIONS

Kinetic and static perimetry complement each other as diagnostic methods to obtain information about damage to the visual pathway caused by these tumors.

[Clinical characteristics of Cuban epidemic neuropathy]

INTRODUCTION

At the beginning of 1992 an epidemic neuropathy was seen in Cuba.

MATERIAL AND METHODS

To determine the clinical characteristics we studied the clinical and neurological features, cerebrospinal fluid, and did neurophysiological investigations and sural nerve biopsies.

RESULTS

Sixty patients were studied. Of these, 42 (70%) had polyneuropathy which was predominantly peripheral and 18 (30%) had combined forms. Most patients had asthenia and weight loss. The polyneuropathic effects were mainly in the legs. In 33.3% of the patients there were distal autonomic effects and sphincter disorders. Only 7 patients had hypoacusia. However, subclinical neurosensorial hypoacusia was seen in 33.3%. Optic neuropathy affected central vision bilaterally and symmetrically with temporal pallor of the papilla in half the cases. In 3 patients there was loss of ganglionar nerve fibres of the papillo-macula bundle. The contrast sensitivity visual test was abnormal in some patients with peripheral polyneuropathy, showing subclinical optic neuropathy in these cases. Sensory neuroconduction suggested axonal neuropathy in 30 patients, demyelinating neuropathy in 5 patients, while the remainder were normal. Motor neuroconduction was normal in most patients. Sural nerve biopsy of 27 patients showed axon damage in 96.2% of cases.

CONCLUSIONS

The clinical picture is similar to that seen in nutritional deficiencies and toxic processes.