Potato native and wound periderms are differently affected by down-regulation of FHT, a suberin feruloyl transferase

Potato native and wound healing periderms contain an external multilayered phellem tissue (potato skin) consisting of dead cells whose cell walls are impregnated with suberin polymers. The phellem provides physical and chemical barriers to tuber dehydration, heat transfer, and pathogenic infection. Previous RNAi-mediated gene silencing studies in native periderm have demonstrated a role for a feruloyl transferase (FHT) in suberin biosynthesis and revealed how its down-regulation affects both chemical composition and physiology. To complement these prior analyses and to investigate the impact of FHT deficiency in wound periderms, a bottom-up methodology has been used to analyze soluble tissue extracts and solid polymers concurrently. Multivariate statistical analysis of LC-MS and GC-MS data, augmented by solid-state NMR and thioacidolysis, yields two types of new insights: the chemical compounds responsible for contrasting metabolic profiles of native and wound periderms, and the impact of FHT deficiency in each of these plant tissues. In the current report, we confirm a role for FHT in developing wound periderm and highlight its distinctive features as compared to the corresponding native potato periderm.

Changes in Cell Wall Polymers and Degradability in Maize Mutants Lacking 3'- and 5'-O-Methyltransferases Involved in Lignin Biosynthesis

Caffeoyl coenzyme A 3-O-methyltransferase (CCoAOMT) and caffeic acid-O-methyltransferase (COMT) are key enzymes in the biosynthesis of coniferyl and sinapyl alcohols, the precursors of guaiacyl (G) and syringyl (S) lignin subunits. The function of these enzymes was characterized in single and double mutant maize plants. In this work, we determined that the comt (brown-midrib 3) mutant plants display a reduction of the flavonolignin unit derived from tricin (a dimethylated flavone), demonstrating that COMT is a key enzyme involved in the synthesis of this compound. In contrast, the ccoaomt1 mutants display a wild-type amount of tricin, suggesting that CCoAOMT1 is not essential for the synthesis of this compound. Based on our data, we suggest that CCoAOMT1 is involved in lignin biosynthesis at least in midribs. The phenotype of ccoaomt1 mutant plants displays no alterations, and their lignin content and composition remain unchanged. On the other hand, the ccoaomt1 comt mutant displays phenotypic and lignin alterations similar to those already described for the comt mutant. Although stems from the three mutants display a similar increase of hemicelluloses, the effect on cell wall degradability varies, the cell walls of ccoaomt1 being the most degradable. This suggests that the positive effect of lignin reduction on cell wall degradability of comt and ccoaomt1 comt mutants is counteracted by changes occurring in lignin composition, such as the decreased S/G ratio. In addition, the role of the flavonolignin unit derived from tricin in cell wall degradability is also discussed.

Cell wall modifications triggered by the down-regulation of Coumarate 3-hydroxylase-1 in maize

Coumarate 3-hydroxylase (C3H) catalyzes a key step of the synthesis of the two main lignin subunits, guaiacyl (G) and syringyl (S) in dicotyledonous species. As no functional data are available in regards to this enzyme in monocotyledonous species, we generated C3H1 knock-down maize plants. The results obtained indicate that C3H1 participates in lignin biosynthesis as its down-regulation redirects the phenylpropanoid flux: as a result, increased amounts of p-hydroxyphenyl (H) units, lignin-associated ferulates and the flavone tricin were detected in transgenic stems cell walls. Altogether, these changes make stem cell walls more degradable in the most C3H1-repressed plants, despite their unaltered polysaccharide content. The increase in H monomers is moderate compared to C3H deficient Arabidopsis and alfalfa plants. This could be due to the existence of a second maize C3H protein (C3H2) that can compensate the reduced levels of C3H1 in these C3H1-RNAi maize plants. The reduced expression of C3H1 alters the macroscopic phenotype of the plants, whose growth is inhibited proportionally to the extent of C3H1 repression. Finally, the down-regulation of C3H1 also increases the synthesis of flavonoids, leading to the accumulation of anthocyanins in transgenic leaves.

AtMYB7, a new player in the regulation of UV-sunscreens in Arabidopsis thaliana

The phenylpropanoid metabolic pathway provides a wide variety of essential compounds for plants. Together with sinapate esters, in Brassicaceae species, flavonoids play an important role in protecting plants against UV irradiation. In this work we have characterized Arabidopsis thaliana AtMYB7, the closest homolog of AtMYB4 and AtMYB32, described as repressors of different branches of phenylpropanoid metabolism. The characterization of atmyb7 plants revealed an induction of several genes involved in flavonol biosynthesis and an increased amount of these compounds. In addition, AtMYB7 gene expression is repressed by AtMYB4. As a consequence, the atmyb4 mutant plants present a reduction of flavonol contents, indicating once more that AtMYB7 represses flavonol biosynthesis. Our results also show that AtMYB7 gene expression is induced by salt stress. Induction assays indicated that AtMYB7 represses several genes of the flavonoid pathway, DFR and UGT being early targets of this transcription factor. The results obtained indicate that AtMYB7 is a repressor of flavonol biosynthesis and also led us to propose AtMYB4 and AtMYB7 as part of the regulatory mechanism controlling the balance of the main A. thaliana UV-sunscreens.

Altered lignin biosynthesis improves cellulosic bioethanol production in transgenic maize plants down-regulated for cinnamyl alcohol dehydrogenase

Cinnamyl alcohol dehydrogenase (CAD) is a key enzyme involved in the last step of monolignol biosynthesis. The effect of CAD down-regulation on lignin production was investigated through a transgenic approach in maize. Transgenic CAD-RNAi plants show a different degree of enzymatic reduction depending on the analyzed tissue and show alterations in cell wall composition. Cell walls of CAD-RNAi stems contain a lignin polymer with a slight reduction in the S-to-G ratio without affecting the total lignin content. In addition, these cell walls accumulate higher levels of cellulose and arabinoxylans. In contrast, cell walls of CAD-RNAi midribs present a reduction in the total lignin content and of cell wall polysaccharides. In vitro degradability assays showed that, although to a different extent, the changes induced by the repression of CAD activity produced midribs and stems more degradable than wild-type plants. CAD-RNAi plants grown in the field presented a wild-type phenotype and produced higher amounts of dry biomass. Cellulosic bioethanol assays revealed that CAD-RNAi biomass produced higher levels of ethanol compared to wild-type, making CAD a good target to improve both the nutritional and energetic values of maize lignocellulosic biomass.

ZmMYB31 directly represses maize lignin genes and redirects the phenylpropanoid metabolic flux

Few regulators of phenylpropanoids have been identified in monocots having potential as biofuel crops. Here we demonstrate the role of the maize (Zea mays) R2R3-MYB factor ZmMYB31 in the control of the phenylpropanoid pathway. We determined its in vitro consensus DNA-binding sequence as ACC(T)/(A) ACC, and chromatin immunoprecipitation (ChIP) established that it interacts with two lignin gene promoters in vivo. To explore the potential of ZmMYB31 as a regulator of phenylpropanoids in other plants, its role in the regulation of the phenylpropanoid pathway was further investigated in Arabidopsis thaliana. ZmMYB31 downregulates several genes involved in the synthesis of monolignols and transgenic plants are dwarf and show a significantly reduced lignin content with unaltered polymer composition. We demonstrate that these changes increase cell wall degradability of the transgenic plants. In addition, ZmMYB31 represses the synthesis of sinapoylmalate, resulting in plants that are more sensitive to UV irradiation, and induces several stress-related proteins. Our results suggest that, as an indirect effect of repression of lignin biosynthesis, transgenic plants redirect carbon flux towards the biosynthesis of anthocyanins. Thus, ZmMYB31 can be considered a good candidate for the manipulation of lignin biosynthesis in biotechnological applications.

The filtrum remodelling with combined Er:YAG CO 2 laser resurfacing

BACKGROUND

Upper lip wrinkles develop with aging and they can be successfully treated with laser resurfacing. The treatment eliminates the wrinkles and, ideally, should also recover the aesthetic configuration.

METHODS

This report includes 32 patients treated for wrinkles of the upper lip with the Derma K. The first pass was done using 29 J/cm2, 5 Hz, 3 mm collimated spot size, plus the CO2 laser 5 W, 50% duty cycle, 50% overlapping. Following this pass, Derma K was reprogrammed to emit only with the Er:YAG at 1.4 J/cm2, 10 Hz, approximately 50% overlapping and with a beam diameter of 3 mm. Then, several passes were done where wrinkles could still be seen, focusing on the area corresponding to the filtrum. Biopsies were taken to examine possible particular implications of underlying muscle and its role in the recovery of anatomic aesthetics of young lip characteristics when using the proposed technique.

RESULTS

Using Derma K resurfacing with extra passes of the Er:YAG at relatively low density, at the aforementioned area, it was possible to achieve the recovery of the aesthetic youthful appearance of the upper lip. Also, the shape of the filtrum recovered its youthful appearance together with the cupid's bow shape. Histology samples collected at the end of resurfacing showed that the laser thermal effect was also related to muscle fibres due to the proximity of this layer to the dermis because of the narrow subcutaneous fat layer.

CONCLUSION

The combination of Er:YAG and CO2 laser of Derma K has potential to enhance the results of resurfacing for elimination of wrinkles of the upper lip. Moreover, the fact that only one laser pass of high energy density is used permits clear and secure control of treatment, preventing complications and obtaining good results.

Effects of skin cleaning modes on the condition of collagen and elastin after laser resurfacing

BACKGROUND

Laser resurfacing is now widely used for the treatment of facial wrinkles, photoaging and acne scars and is usually combined with comparatively aggressive methods of cleaning detritus off the treated area after each laser pass.

OBJECTIVE

This study aims to evaluate two different cleaning methods (damp gauze or damp large-tip cotton buds) in order to elucidate their influence on the healing process, if any. The left or right preauricular area, chosen at random on 10 patients undergoing periocular and perioral resurfacing with the same laser system, was cleaned after each laser pass with damp gauze (Group G) and the contralateral side with the large-tip cotton buds (Group C). Post-resurfacing oedema and erythema were observed in the preauricular areas and rated by the same experienced observer immediately after treatment and at 14, 30, 45, 60 and 90 days.

RESULTS

Oedema was slightly more noticeable initially in Group G patients, but the erythema was more intense and lasted longer in the gauze-cleaned tissue. The sites were biopsied at 90 days and the samples sent for blinded histological evaluation to assess the degree of collagen and elastin fibre compaction. The histology demonstrated that the tissue from Group G achieved, at 90 days, better compaction of collagen and elastin fibres than that from Group C.

CONCLUSIONS

It is suggested that the abrasive action caused by the gauze adds to the existing stimulative inflammatory reaction following CO2 laser resurfacing, which augments the collagen and fibre compaction response in the tissue. Comparatively aggressive cleaning with damp gauze may therefore be preferable to other methods when performing laser resurfacing.

The maize ZmMYB42 represses the phenylpropanoid pathway and affects the cell wall structure, composition and degradability in Arabidopsis thaliana

The involvement of the maize ZmMYB42 R2R3-MYB factor in the phenylpropanoid pathway and cell wall structure and composition was investigated by overexpression in Arabidopsis thaliana. ZmMYB42 down-regulates several genes of the lignin pathway and this effect reduces the lignin content in all lignified tissues. In addition, ZmMYB42 plants generate a lignin polymer with a decreased S to G ratio through the enrichment in H and G subunits and depletion in S subunits. This transcription factor also regulates other genes involved in the synthesis of sinapate esters and flavonoids. Furthermore, ZmMYB42 affects the cell wall structure and degradability, and its polysaccharide composition. Together, these results suggest that ZmMYB42 may be part of the regulatory network controlling the phenylpropanoid biosynthetic pathway.

ZmXTH1, a new xyloglucan endotransglucosylase/hydrolase in maize, affects cell wall structure and composition in Arabidopsis thaliana

Xyloglucan endotransglucosylase/hydrolases (XTHs; EC 2.4.1.207 and/or EC 3.2.1.151) are enzymes involved in the modification of cell wall structure by cleaving and, often, also re-joining xyloglucan molecules in primary plant cell walls. Using a pool of antibodies raised against an enriched cell wall protein fraction, a new XTH cDNA in maize, ZmXTH1, has been isolated from a cDNA expression library obtained from the elongation zone of the maize root. The predicted protein has a putative N-terminal signal peptide and possesses the typical domains of this enzyme family, such as a catalytic domain that is homologous to that of Bacillus macerans beta-glucanase, a putative N-glycosylation motif, and four cysteine residues in the central and C terminal regions of the ZmXTH1 protein. Phylogenetic analysis of ZmXTH1 reveals that it belongs to subgroup 4, so far only reported from Poaceae monocot species. ZmXTH1 has been expressed in Pichia pastoris (a methylotrophic yeast) and the recombinant enzyme showed xyloglucan endotransglucosylase but not xyloglucan endohydrolase activity, representing the first enzyme belonging to subgroup 4 characterized in maize so far. Expression data indicate that ZmXTH1 is expressed in elongating tissues, modulated by culture conditions, and induced by gibberellins. Transient expression assays in onion cells reveal that ZmXTH1 is directed to the cell wall, although weakly bound. Finally, Arabidopsis thaliana plants expressing ZmXTH1 show slightly increased xyloglucan endohydrolase activity and alterations in the cell wall structure and composition.

Risk of acute liver injury associated with the use of drugs: a multicentre population survey

BACKGROUND

Acute liver injury of uncertain aetiology is often drug related and quantitative information about the associated risk is scarce.

AIM

To estimate the risk of acute liver injury associated with the use of drugs.

METHODS

In a population survey study, 126 cases of acute liver injury were prospectively assembled from January 1993 to December 1999, in patients over 15 years of age, in 12 hospitals in Barcelona (Spain). We estimated the relative risk for each drug as the ratio between the incidence of acute liver injury among the exposed population to the drug and the incidence of acute liver injury among those not exposed to it. Drug consumption data were used to estimate the exposed population.

RESULTS

Isoniazid, pyrazinamide, rifampicin, amoxicillin with clavulanic acid, erythromicin, chlorpromazine, nimesulide, and ticlopidine presented the highest risk (point relative risk > 25). Amoxicillin, metoclopramide, captopril and enalapril, furosemide, hydrochlorothiazide, fluoxetine, paroxetine, diazepam, alprazolam, lorazepam, metamizole, low-dose acetylsalicylic acid and salbutamol showed the lowest risk (point relative risk < 5).

CONCLUSIONS

This study provides a risk estimation of serious liver disease for various drugs that will be useful in its diagnosis and management, and when comparing with the drug therapeutic benefit in each indication. Some observed associations would be worth specific studies.

Down-regulation of the maize and Arabidopsis thaliana caffeic acid O-methyl-transferase genes by two new maize R2R3-MYB transcription factors

The maize (Zea mays L.) caffeic acid O-methyl-transferase (COMT) is a key enzyme in the biosynthesis of lignin. In this work we have characterized the involvement of COMT in the lignification process through the study of the molecular mechanisms involved in its regulation. The examination of the maize COMT gene promoter revealed a putative ACIII box, typically recognized by R2R3-MYB transcription factors. We used the sequence of known R2R3-MYB factors to isolate five maize R2R3-MYB factors (ZmMYB2, ZmMYB8, ZmMYB31, ZmMYB39, and ZmMYB42) and study their possible roles as regulators of the maize COMT gene. The factors ZmMYB8, ZmMY31, and ZmMYB42 belong to the subgroup 4 of the R2R3-MYB family along with other factors associated with lignin biosynthesis repression. In addition, the induction pattern of ZmMYB31 and ZmMYB42 gene expression on wounding is that expected for repressors of the maize COMT gene. Arabidopsis thaliana plants over-expressing ZmMYB31 and ZmMYB42 down-regulate both the A. thaliana and the maize COMT genes. Furthermore, the over-expression of ZmMYB31 and ZmMYB42 also affect the expression of other genes of the lignin pathway and produces a decrease in lignin content of the transgenic plants.

Effect of 655-nm diode laser on dog sperm motility

Sperm motility depends on energy consumption. Low-level laser irradiation increases adenosin triphosphate (ATP) production and energy supply to the cell. The aim of this study is to analyse whether the irradiation affects the parameters that characterise dog sperm motility. Fresh dog sperm samples were divided into four groups and irradiated with a 655-nm continuous-wave diode laser with varying doses: 0 (control), 4, 6 and 10 J/cm(2). At 0, 15 and 45 min following irradiation, pictures were taken of all the groups in order to study motility with computer-aided sperm analysis (CASA). Functional tests were also performed. Average path velocity (VAP), linear coefficient (Lin) and beat cross frequency (BCF) were statistically and significantly different when compared to the control. The functional tests also showed a significant difference. At these parameters, the 655-nm continuous-wave diode laser improves the speed and linear coefficient of the sperm.

AtPng1p. The first plant transglutaminase

Studies have revealed in plant chloroplasts, mitochondria, cell walls, and cytoplasm the existence of transglutaminase (TGase) activities, similar to those known in animals and prokaryotes having mainly structural roles, but no protein has been associated to this type of activity in plants. A recent computational analysis has shown in Arabidopsis the presence of a gene, AtPng1p, which encodes a putative N-glycanase. AtPng1p contains the Cys-His-Asp triad present in the TGase catalytic domain. AtPng1p is a single gene expressed ubiquitously in the plant but at low levels in all light-assayed conditions. The recombinant AtPng1p protein could be immuno-detected using animal TGase antibodies. Furthermore, western-blot analysis using antibodies raised against the recombinant AtPng1p protein have lead to its detection in microsomal fraction. The purified protein links polyamines-spermine (Spm) > spermidine (Spd) > putrescine (Put)-and biotin-cadaverine to dimethylcasein in a calcium-dependent manner. Analyses of the gamma-glutamyl-derivatives revealed that the formation of covalent linkages between proteins and polyamines occurs via the transamidation of gamma-glutamyl residues of the substrate, confirming that the AtPng1p gene product acts as a TGase. The Ca(2+)- and GTP-dependent cross-linking activity of the AtPng1p protein can be visualized by the polymerization of bovine serum albumine, obtained, like the commercial TGase, at basic pH and in the presence of dithiotreitol. To our knowledge, this is the first reported plant protein, characterized at molecular level, showing TGase activity, as all its parameters analyzed so far agree with those typically exhibited by the animal TGases.

Nucleotide diversity of the ZmPox3 maize peroxidase gene: relationships between a MITE insertion in exon 2 and variation in forage maize digestibility

BACKGROUND

Polymorphisms were investigated within the ZmPox3 maize peroxidase gene, possibly involved in lignin biosynthesis because of its colocalization with a cluster of QTL related to lignin content and cell wall digestibility. The purpose of this study was to identify, on the basis of 37 maize lines chosen for their varying degrees of cell wall digestibility and representative of temperate regions germplasm, ZmPox3 haplotypes or individual polymorphisms possibly associated with digestibility.

RESULTS

Numerous haplotypes with high diversity were identified. Frequency of nucleotide changes was high with on average one SNP every 57 bp. Nucleotide diversity was not equally distributed among site categories: the estimated pi was on average eight times higher for silent sites than for non-synonymous sites. Numerous sites were in linkage disequilibrium that decayed with increasing physical distance. A zmPox3 mutant allele, carrying an insertion of a transposable element in the second exon, was found in lines derived from the early flint inbred line, F7. This element possesses many structural features of miniature inverted-repeat transposable elements (MITE). The mutant allele encodes a truncated protein lacking important functional sites. An ANOVA performed with a subset of 31 maize lines indicated that the transposable element was significantly associated with cell wall digestibility. This association was confirmed using an additional set of 25 flint lines related to F7. Moreover, RT-PCR experiments revealed a decreased amount of corresponding mRNA in plants with the MITE insertion.

CONCLUSION

These results showed that ZmPox3 could possibly be involved in monolignol polymerisation, and that a deficiency in ZmPox3 peroxidase activity seemingly has a negative effect on cell wall digestibility. Also, genetic diversity analyses of ZmPox3 indicated that this peroxidase could be a relevant target for grass digestibility improvement using specific allele introgressions.

Unsupervised self-testing of airway obstruction by forced oscillation at the patient's home

As active patient cooperation is not required, the forced oscillation technique (FOT) could be suitable for measuring airway obstruction in routine home applications. Nevertheless, FOT has never been used at the patient's home to date. The aim of this study was to assess the feasibility of FOT and the reproducibility of measured respiratory resistance (Rrs) in routine patient self-testing at home. Altogether, nine asthmatic patients self-measured their Rrs with a portable FOT device and spirometry for 10-14 days, in the morning and evening, and before and after bronchodilator inhalation. During each measurement session, the patients carried out four consecutive FOT measurements. Grubbs' discordancy test for detecting outliers was used to evaluate intermeasure reliability. Only 4.9% of Rrs data reported by patients were rejected as artefacts. The coefficient of variation of Rrs was 7.9 +/- 6.3% (mean +/- SD). When compared with spirometry, the per cent change in Rrs for detecting a positive bronchodilator response showed an 83% sensitivity and 72% specificity. Unsupervised self-measurement of respiratory resistance at the patient's home provided results similar to those obtained by a technician in a lung function lab. Forced oscillation technique could be a useful tool for the routine follow-up of asthmatic patients at home.

Characterisation of maize peroxidases having differential patterns of mRNA accumulation in relation to lignifying tissues

Among other enzymes, peroxidases have been proposed to participate in the latest steps of lignin biosynthesis. In order to identify new proteins involved in such mechanism of lignification in maize, we have isolated three cDNAs coding for three different peroxidases, named ZmPox1, ZmPox2, and ZmPox3, respectively. Computational analyses of these three proteins correlate with features typically attributed to heme-containing plant peroxidases of approximately 300 amino acid residues. Although with different expression levels, ZmPox2 and ZmPox3 mRNAs are accumulated in the elongating region of young roots but not in the root tips. In addition, the ZmPox2 mRNA levels are up-regulated by wounding and ethylene treatments. However, ZmPox1 is also expressed in the root tip meristems, where lignification does not occur. Finally, in situ hybridisations indicate that ZmPox2 mRNA localises in vascular tissues and epidermis. Although ZmPox1 mRNA localises in the same regions as ZmPox2 mRNA in root tips, its mRNA is only detected in the epidermis but not in the vascular tissues of young roots, suggesting that the function of ZmPox1 is not correlated to lignification. In addition, although ZmPox3 mRNA is also detected in the regions where lignification occurs, the involvement of this peroxidase in such a mechanism remains to be further investigated due to its very low expression level. Therefore, based on its amino acid sequence and mRNA accumulation and localisation patterns, the involvement of ZmPox2 in the latest steps of lignification is discussed.

Down-regulation of caffeic acid o-methyltransferase in maize revisited using a transgenic approach

Transgenic maize (Zea mays) plants were generated with a construct harboring a maize caffeic acid O-methyltransferase (COMT) cDNA in the antisense (AS) orientation under the control of the maize Adh1 (alcohol dehydrogenase) promoter. Adh1-driven beta-glucuronidase expression was localized in vascular tissues and lignifying sclerenchyma, indicating its suitability in transgenic experiments aimed at modifying lignin content and composition. One line of AS plants, COMT-AS, displayed a significant reduction in COMT activity (15%-30% residual activity) and barely detectable amounts of COMT protein as determined by western-blot analysis. In this line, transgenes were shown to be stably integrated in the genome and transmitted to the progeny. Biochemical analysis of COMT-AS showed: (a) a strong decrease in Klason lignin content at the flowering stage, (b) a decrease in syringyl units, (c) a lower p-coumaric acid content, and (d) the occurrence of unusual 5-OH guaiacyl units. These results are reminiscent of some characteristics already observed for the maize bm3 (brown-midrib3) mutant, as well as for COMT down-regulated dicots. However, as compared with bm3, COMT down-regulation in the COMT-AS line is less severe in that it is restricted to sclerenchyma cells. To our knowledge, this is the first time that an AS strategy has been applied to modify lignin biosynthesis in a grass species.

A portable forced oscillation device for respiratory home monitoring

The increase in the prevalence of chronic respiratory diseases has resulted in a rise in health services provided at home. The forced oscillation technique (FOT) proves to be a useful tool when it is desired to assess lung function noninvasively, and particularly for patients in whom spirometry cannot be applied. As no portable FOT device is currently available, the aim of this study was to design and test a portable FOT system for ambulatory and home care applications. The system devised is based on a microprocessor, which allows online computation of respiratory resistance (Rrs) and reactance (Xrs) and reliability indices. The portable device was compared with a conventional FOT system by using signals from 14 patients with chronic respiratory disease. This device has the same computation capabilities and flexibility as conventional FOT systems and meets the requirements for home application. Rrs (14.2 +/- 6.0 cmH2O x s x L(-1), mean +/- SD) and Xrs (-5.3 +/- 2.7 cmH2O x s x L(-1)) measured at 5 Hz by the portable system virtually coincided with those computed with the reference conventional FOT system: mean differences +/-SD were 0.074 +/- 0.025 and 0.005 +/- 0.009 cmH2O x s x L(-1), respectively. This portable forced oscillation technique device could be a useful tool for monitoring respiratory mechanics in ambulatory and home care applications.

Comparison of the low level laser therapy effects on cultured human gingival fibroblasts proliferation using different irradiance and same fluence

BACKGROUND AND OBJECTIVE

The low level laser therapy (LLLT) has been used in Dentistry to improve wound healing. In order to analyse the effect of LLLT on the in vitro proliferation of gingival fibroblasts we developed a primary culture of human gingival fibroblasts.

STUDY DESIGN/MATERIALS AND METHODS

The cell line named LMF was grown in Dulbecco's Modified Eagle's medium (DME) with either 5% (nutritional deficit) or 10% fetal bovine serum (fbs). Laser irradiation was carried out with diode lasers with the following wavelengths: 670 nm (L1), 780 nm (L2), 692 nm (L3), and 786 nm (L4). The fluence was fixed in 2 J/cm(2). For growth analysis, control (not irradiated) and treated cultures (irradiated) were plated in 60 mm diameter culture dishes for 12 h before the irradiation.

RESULTS

We found that cells cultured in nutritional deficit condition grown in medium supplemented by only 5% fbs presented a cell proliferation rate significantly smaller that cell grown in ideal culture conditions (10% fbs). However, when irradiated, cells in nutritional deficit presented cell growth similar or higher than that of control cells grown in ideal culture conditions. Using the same fluence, the infrared laser induced a higher cell proliferation than visible laser when the power outputs were different. However, lasers of equal power output presented similar effect on cell growth independently of their wavelengths.

CONCLUSIONS

The LLLT acts by improving the in vitro fibroblast proliferation and a smaller laser exposure time results in higher proliferation.

Clinical and histologic effects of facial skin rejuvenation with pulsed- and continuous-wave flash-scanned CO(2) lasers

LEARNING OBJECTIVES

The reader is presumed to have some understanding of the use of lasers in skin resurfacing. After studying the article, the participant should be able to: Physicians may earn 1 hour of Category 1 CME credit by successfully completing the examination based on material covered in this article. The examination begins on page 409.

BACKGROUND

The selection of the ideal laser for facial resurfacing is debatable.

OBJECTIVE

The purpose of the study was to determine whether any clinical and histologic differences existed in short- and long-term results after treatment with the Coherent UltraPulse 5000G laser (a pulsed laser; PL) and the Sharplan Silk Touch laser (a continuous-wave laser [CWL] with a flash scanner).

METHODS

Eight patients underwent facial resurfacing treatment on different areas. In each case, one side was treated with the PL and the other with the CWL. The condition of the patients and the treated tissue were monitored periodically after treatment. Histologic assessment of punch biopsies was performed 3 months and 1 year after treatment with hematoxylin-eosin, Masson trichromic, and Verhoeff's stains.

RESULTS

The areas treated with the PL achieved earlier epithelialization with a good appearance. Longer-lasting erythema was observed on the side treated with the CWL. On a histologic level, although the PL-treated tissue epithelialized more quickly, at 3 months and 1 year the collagen was better compacted and better aligned in the CWL-treated tissue, and the macroscopic appearance of the CWL-treated areas was more enhanced.

CONCLUSIONS

The more active vascularization seen in the CWL-treated tissue, associated with the longer-lasting erythema and possibly greater collateral thermal injury, is possibly the reason for the better collagenization and remodeling of collagen and elastin fibers as compared with the results with the PL-treated tissue. This may explain the longer effect associated with CWL treatment. The clinician would do well to bear in mind the histologic findings as well as the macroscopic clinical results when assessing the long-term effects of laser skin resurfacing. (Aesthetic Surg J 2001;21:399-411.).

Forced oscillation measurements do not affect upper airway muscle tone or sleep in clinical studies

Upper airway obstruction in the sleep apnoea/hypopnoea syndrome (SAHS) can be easily assessed by measuring respiratory impedance with the forced oscillation technique (FOT). This methodology has been proposed as a useful clinical tool both for the diagnosis of sleep breathing disorders and for continuous positive airway pressure (CPAP) titration. However, previous studies suggest that the application of high-frequency pressure oscillation to the upper airway may induce changes in the electroencephalogram (EEG) or upper airway muscle function. The effect of FOT measurements on upper airway muscle tone and EEG in clinical sleep studies was examined. Seven patients with moderate SAHS were included (age: 54+/-11 yrs; apnoea/hypopnoea index: 43+/-21 events x h(-1); body mass index: 30+/-2 kg x m(-2)). Genioglossus surface electromyogram activity (EMGgg) and EEG signal were analysed with and without FOT application (frequency: 5 Hz and 30 Hz; peak-to-peak pressure oscillation: 1 cmH2O) during stable sleep. Measurements were carried out in two different situations. Step 1: applying FOT during episodes of obstructive events or flow limitation; and step 2: during prolonged periods of normal breathing at optimal CPAP. The root mean square of EMGgg activity and fast Fourier analysis (alpha and delta bands) of the EEG signal were performed. The application of FOT did not increase EMGgg activity in any of the situations studied. In addition, no evidence of the effects on EEG was found: alpha/delta relationship: awake:0.70, baseline sleep:0.13, FOT(5 Hz):0.18, FOT(30 Hz):0.11. The presented results suggest that the use of forced oscillation technique over the ranges of frequency and amplitude proposed for clinical sleep studies does not induce changes in upper airway muscle activity and neurological variables in patients with sleep apnoea/hypopnoea syndrome.

Evaluation of a simplified oscillation technique for assessing airway obstruction in sleep apnoea

The forced oscillation technique (FOT) is a noninvasive method that is useful for assessing airway obstruction and for titrating continuous positive airway pressure (CPAP) in patients with sleep apnoea. The aim was to evaluate the routine applicability of a simplified FOT set-up based on recording pressure and flow at the level of the CPAP device, i.e. obviating the need for connecting the transducers to the nasal mask. A correction to account for the tubing and the exhaust port was applied. This simplified FOT was evaluated on nine patients with moderate or severe sleep apnoea during routine CPAP titration. Patient impedance measured by the simplified FOT ([Z]) was compared with actual patient impedance ([Zrs]) measured simultaneously with a reference FOT based on recording pressure and flow at the nasal mask. An excellent agreement was found between [Z] and [Zrs] over the wide range of airway obstruction explored (4.8-72.1 cmH2O x s x L(-1)): [Z] = [Zrs] x 0.86 + 1.3 cmH2O x s x L(-1) (r = 0.99). Moreover, the simplified and the conventional FOT settings detected the same respiratory events during sleep. These results demonstrate that this simplified FOT is applicable for measuring airway obstruction during routine sleep studies in patients with sleep apnoea.

Relevance of linearizing nasal prongs for assessing hypopneas and flow limitation during sleep

Respiratory disturbances in patients with the sleep apnea-hypopnea syndrome (SAHS) may be detected by means of nasal prongs (NP) pressure (PNP). Nevertheless, PNP is nonlinearly related to flow (V). Our aim was to demonstrate the relevance of linearizing P NP for assessing hypopneas and flow limitation in SAHS. V was measured with a pneumotachograph during the hypopneas and flow limitation events in a continuous positive airway pressure (CPAP) titration in six patients with severe SAHS. These flow patterns were reproduced by a flow generator through an analog of the nares and recorded by NP. PNP was linearized [V NP = (PNP)1/2] by a specially designed analog circuit. For each event we used V, P NP, and V NP to compute the hypopnea flow amplitude (HFA) and a flow limitation index (FLI). Owing to NP nonlinearity, PNP considerably misestimated HFA and FLI. By contrast, V NP provided HFA and FLI values that were very close to those obtained from V: HFA (V NP) = 1.098. HFA(V) - 0.063 (r2 = 0.98) and FLI(V NP) = 1.044. FLI(V) + 0.004 (r2 = 0.99). Square-root linearization of NP greatly increases the accuracy of quantifying hypopneas and flow limitation. This procedure, which could be readily carried out in routine practice by means of the analog circuit we developed, is of interest in optimizing the assessment of respiratory sleep disturbances in SAHS.

Immunogold localization of a transglutaminase related to grana development in different maize cell types

A comparative study of the subcellular localization of a plant transglutaminase (TGase; EC 2.3.2.13) in various in vivo and in vitro maize cell types was carried out with a polyclonal antibody raised against a 58 kDa TGase purified from Helianthus tuberosus leaves. Immunocytochemical staining, followed by electron microscopy, showed that this enzyme was markedly present in the grana-appressed thylakoids of mature chloroplasts of the light-exposed cells. Moreover, during embryogenic callus chloroplast differentiation, the abundance of TGase in the grana-appressed thylakoids depended on the degree of grana development and was greater than in mature leaf chloroplasts. In addition to the 58 kDa form, two other forms of the protein (of 77 and 34 kDa) were obtained by Western blot. The 77 kDa form might correspond to the inactive form and was immunodetected in dense vesicles observed in dark-grown embryogenic callus cells. In adult leaves, the enzyme was also markedly present in the grana-appressed thylakoids of the mesophyll cell chloroplasts, though very scarce and dispersed in the bundle-sheath cell chloroplasts (which do not contain grana). The concordance of these localizations with those described for the light-harvesting antenna proteins of the photosystem II suggests that it is possible that this TGase has a functional role in photosynthesis, perhaps modulating the photosynthetic efficiency and the absorption of excess light by means of polyamine conjugation to the antenna proteins.

Involvement of a maize proline-rich protein in secondary cell wall formation as deduced from its specific mRNA localization

A clone encoding a proline-rich protein (ZmPRP) has been obtained from maize root by differential screening of a maturing elongation root cDNA library. The amino acid sequence deduced from the full-length cDNA contains a putative signal peptide and a highly repetitive sequence containing the PEPK motif, indicating that the ZmPRP mRNA may code for a cell wall protein. The PEPK repeat is also found in a previously reported wheat sequence but differs from the repeated sequences found in hydroxyproline-rich glycoproteins (HRGP) and in dicot proline-rich proteins (PRP). In the maize genome, the ZmPRP protein is encoded by a single gene that is expressed in maturing regions of the root, in the hypocotyl and in the pericarp. In these organs, the ZmPRP mRNA accumulates in the xylem and surrounding cells, and in the epidermis. No ZmPRP mRNA was found in the phloem. The pattern of mRNA accumulation is very similar to the one observed for genes coding for proteins involved in lignin biosynthesis and, like most cell wall proteins, ZmPRP synthesis is also induced by wounding. These data support the hypothesis that ZmPRP is a member of a new class of fibrous proteins involved in the secondary cell wall formation in monocot species.

Electron microscopy comparison of CO2 laser flash scanning and pulse technology one year after skin resurfacing

BACKGROUND

The recent adaptation of laser technology in plastic and dermatologic surgery has provided a means to reduce efficiently the irregularities of the surface of the skin. Previous studies have analyzed the short- and medium-term clinical and histologic results of two laser systems: the Sharplan 40C SilkTouch and the 5000C Coherent Ultrapulse with Computer Pattern Generator (CPG). This paper contains the long-term ultrastructural findings observed with the aid of transmission electron microscopy (TEM).

MATERIALS AND METHODS

Twenty skin biopsy specimens were taken from ten Caucasion patients, between 54 and 72 years of age, who had undergone facial skin resurfacing with a CO2 laser 1 year previously. The treated areas of the face were divided into two equal parts. One half of the face was treated with the Sharplan SilkTouch laser and the other half with the Coherent Ultrapulse laser. Using TEM, the cell composition of the epidermis was studied ultrastructurally, as were the dermal-epidermal junction (DEJ) and the different fibers and cells in the superficial and middle dermis.

RESULTS

On the side treated by the Sharplan laser, little melanin was observed, the DEJ was thicker, and there were abundant collagen fibers well compacted in the dermis. Also present was abundant elastin fiber with scarce interstitial spaces. On the side treated by the Coherent, the melanin was abundant and the DEJ was well structured. There were fibroblasts with lax chromatin in the dermis and collagen fibers in the papillary dermis oriented in a vertical and horizontal manner in relation to the epidermis. There was little elastin. The interstitial spaces were abundant.

CONCLUSIONS

The Sharplan laser system seems to provoke a significantly more intense tissue response, with abundant dermal collagen and elastic fibers. This indicates that the Sharplan 40C SilkTouch might produce longer lasting clinical effects.

Maize alpha-tubulin genes are expressed according to specific patterns of cell differentiation

In the past few years many alpha- and beta-tubulin genes of different organisms have been cloned and studied, and in most systems studied they constitute multigene families. In plants, most studies have been done in Arabidopsis thaliana and Zea mays. In this paper, the study of mRNA accumulation by in situ hybridization and the activity of three maize alpha-tubulin gene promoters (tua1, tua2 and tua3) in transgenic tobacco plants are described. In maize, the expression of these three tubulin isotypes differ in the root and shoot apex and is associated with different groups of cells throughout the distinct stages of cell differentiation. In transgenic tobacco plants the promoters of the genes, fused to the uidA reporter gene (GUS), direct expression to the same tissues observed by in situ hybridization experiments. The tua1 promoter is mainly active in cortex-producing meristematic cells and in pollen, whereas tua3 is active in cells which are differentiating to form vascular bundles in the root and shoot apices. The accumulation of tua2 mRNA is detected by RNA blot in a similar form as tua1, but at a very much low level. In situ hybridization indicates that the tua2 mRNA specifically accumulates in the maize root epidermis. No GUS staining was detected in transgenic tobacco plants with the tua2 promoter. The difference in expression of the specific genes may be linked to processes where microtubules have different functions, suggesting that in plants, as in animals, there are differences in the function of the tubulin isotypes.

Effects of silymarin in alcoholic patients with cirrhosis of the liver: results of a controlled, double-blind, randomized and multicenter trial

BACKGROUND/AIMS

Silymarin has protective effects in different experimental conditions, but its efficacy in human liver cirrhosis has not been completely established. Therefore, this study was carried out to determine the effect of silymarin in alcoholics with liver cirrhosis with respect to survival and clinical and laboratory changes.

METHODS

From February 1986 to June 1989, we enrolled 200 alcoholics with histologically or laparoscopically proven liver cirrhosis in a randomized, double-blind multicenter trial comparing 450 mg of silymarin (150 mg/ three times per day) with placebo. The primary outcome was time to death, and the secondary outcome was the progression of liver failure. Additional analyses were also performed in 75 patients in whom anti-hepatitis C virus antibodies were measured after completion of the trial.

RESULTS

One hundred and three patients were assigned to receive silymarin and 97 to receive placebo. The two groups were well matched for demographic and baseline clinical and laboratory features. A 2-year study period was completed in 125 patients (57 receiving silymarin and 68 receiving placebo). Twenty-nine patients (15 receiving silymarin, and 14 receiving placebo) died during the trial. Survival was similar in patients receiving silymarin or placebo. The effect of silymarin on survival was not influenced by sex, the persistence of alcohol intake, the severity of liver dysfunction or by the presence of alcoholic hepatitis in the liver biopsy. Silymarin did not have any significant effect on the course of the disease. No relevant side-effects were observed in any group.

CONCLUSIONS

The results of this study indicate that silymarin has no effect on survival and the clinical course in alcoholics with liver cirrhosis.

A clinical and histological comparison of flashscanning versus pulsed technology in carbon dioxide laser facial skin resurfacing

BACKGROUND

Two different carbon dioxide (CO2) laser systems are currently in use for skin resurfacing. The vast majority of lasers use a pulsed beam, like the Coherent 5000C, but Sharplan uses scanning technology.

OBJECTIVE

We describe a clinical and histological comparison of these two laser technologies in order to determine if there are differences in the outcome.

METHODS

Twenty-two female patients underwent facial skin resurfacing using the Coherent 5000C UltraPulse CPG on one side of the face and the Sharplan Silk Touch on the contralateral side of the face. The clinical appearances were assessed periodically after treatment and punch biopsies were taken preoperatively and after 7, 21, and 90 days. Tissue was stained with Hematoxylin-Eosin, Masson Trichrom, and with the Verhoeff technique. Histological evaluation was performed on randomized samples taken from the same patient. Epidermis/dermis expression, collagen compaction, and elastin fiber quantity were compared to evaluate if any differences existed.

RESULTS

The side treated by Coherent healed more rapidly and with excellent cosmesis. Greater erythema was observed on the Sharplan side, but had disappeared at the 90-day evaluation. At this time the quality of the results was similar with no particular difference between the sides treated by the Coherent or the Sharplan lasers. At the histological level, although tissue recovered faster on the Coherent side at the 7-day control, at 90 days the collagen was better compacted and organized on the Sharplan side. Similarly, the quantity of the elastin was significantly more enhanced on the Sharplan side.

CONCLUSION

Irradiated laser energy density in relation to time, and the way that it is delivered, should play an important role at the moment of producing collagen shrinkage. The SilkTouch delivers laser energy more aggressively, thereby producing a more intense inflammatory tissue reaction, which results in slower recovery of tissue, compared with the Coherent CPG. More active enhancement of vascularization found in the Sharplan is likely to be the reason for a more effective collagen proliferation and compaction. These changes, together with the increase in elastin in the dermis, may produce longer lasting effects in skin resurfacing.

The origin and role of erythema after carbon dioxide laser resurfacing. A clinical and histological study

BACKGROUND

Transient erythema, which can last up to 3 months after carbon dioxide (CO2) laser skin resurfacing, is a usual side effect with pulsed or rapidly scanned CO2 lasers.

OBJECTIVE

We evaluated the cause of erythema in the clinical setting and by histology in order to determine if and how we may decrease it, or even eliminate it.

METHODS

Ten patients who underwent resurfacing were recruited to this study. Skin punch biopsies were taken at 0, 7, 21, and 90 days and analyzed by light microscopy.

RESULTS

Erythema was noticed from about day 8, when the crusting on the skin surface was exfoliated. It reached its maximum intensity after 14 days, and had disappeared by 60-90 days. Histology showed an early inflammatory response, with an immature neopithelium, and rich vascularization. The normal epidermis had returned by 90 days, and during this period there was reduced optical scattering and absorption in melanin.

CONCLUSION

Although the erythema is an unwanted side effect in the patient's eyes, it is to be expected and thus represents the effects of a combination of epidermal immaturity, reduced melanin absorption of light, reduced dermal optical scattering, and increased blood flow secondary to the surgically induced inflammatory response.

Dengue in Spanish travelers returning from the tropics

Dengue is seldom recognized as an imported disease in Europe. A prospective clinical study was carried out in 37 travelers suspected to have dengue infection on their return from dengue-endemic areas. Anti-dengue antibodies were found in 24 of 37 patients (14 recent infections and 10 undetermined). The most common features among the recent infections were fever (100%), thrombocytopenia (61.5%), abnormal liver function tests (61.5%), and rash (53.8%). In one case, denguehemorrhagic fever grade III was confirmed and later followed by depression and suicide of the patient. The possibility of local transmission of dengue in Spain is discussed.

Penetration depth of Ultrapulse carbon dioxide laser in human skin

BACKGROUND

Recent technological advances have dramatically increased the use of lasers in skin resurfacing. The first high-power short-pulse laser, Ultrapulse, has found extensive use in dermatology and plastic surgery for skin resurfacing. Reports for penetration depth are at best anecdotal. To our knowledge this is the first report of histological effects of the Ultrapulse in human skin.

OBJECTIVE

To determine the effect of single and repeated (two or three) Ultrapulse laser impacts on volar forearm skin.

METHOD

The volar surface of the arm in four patients received in adjacent areas either one, two, or three pulses, after anesthesia. The treated areas were immediately biopsied, hematoxylin & eosin prepared, and examined.

RESULTS

Increasing the number of passes correlates with increased depth of penetration and thermal ablation. No significant propagation of destructive thermal energy to adjacent tissue was noted.

CONCLUSION

One impact at the tested parameters ablated most of the epidermis. Two impacts superimposed ablated the entire epidermis and the superficial papillary dermis. Three superimposed impacts penetrated to the reticular dermis.

Periocular skin reshaping by CO2 laser coagulation

When blepharoplasty is performed by transconjunctival route, sometimes the excess of skin created by overlaxness of the lower lid does not retract to achieve the desired cosmetic result. We propose a method for controlled retraction of the eyelid by coagulating the skin using the CO2 laser. Thanks to this approach, the lower eyelid's tone recovers and the desired cosmetic appearance is achieved. Results of 37 patients that were treated by 10 W CO2 laser, 5-mm defocused beam diameter, and pulses of 100 ms, are presented. Follow-up shows that periocular skin reshaping by CO2 laser for laxened eyelid is a safe method and it can be considered a good alternative of treatment for blepharochalasis without skin excision.

The maize caffeic acid O-methyltransferase gene promoter is active in transgenic tobacco and maize plant tissues

The pattern of expression directed by the promoter of the maize caffeic acid O-methyltransferase (COMT) gene was studied by histochemical and fluorometric beta-glucuronidase (GUS) analysis in transgenic maize and tobacco plants. The COMT promoter directs GUS expression to the xylem and the other tissues undergoing lignification, and it responds to wounding and to elicitors. In transgenic maize plants, expression of GUS corresponds to the pattern of expression of the endogenous COMT gene as determined by northern analysis and in situ hybridization. The pattern in transgenic tobacco plants clearly shows that the maize promoter sequence is recognized by tobacco transcriptional factors, in spite of the anatomical differences and the evolutionary distance between these two species. The results suggest that the most significant promoter signals that induce the specific expression of the lignin COMT are conserved in different species.

The brown midrib3 (bm3) mutation in maize occurs in the gene encoding caffeic acid O-methyltransferase

The brown midrib mutations are among the earliest described in maize. Plants containing a brown midrib mutation exhibit a reddish brown pigmentation of the leaf midrib starting when there are four to six leaves. These mutations are known to alter lignin composition and digestibility of plants and therefore constitute prime candidates in the breeding of silage maize. Here, we show that two independent brown midrib3 (bm3) mutations have resulted from structural changes in the COMT gene, which encodes the enzyme O-methyltransferase (COMT; EC 2.1.1.6), involved in lignin biosynthesis. Our results indicate that the bm3-1 allele (the reference mutant allele) has arisen from an insertional event producing a COMT mRNA altered in both size and amount. By sequencing a COMT cDNA clone obtained from bm3-1 maize, a retrotransposon with homology to the B5 element has been found to be inserted near the junction of the 3' coding region of the COMT gene intron. The second bm3 allele, bm3-2, has resulted from a deletion of part of the COMT gene. These alterations of the COMT gene were confirmed by DNA gel blot and polymerase chain reaction amplification analyses. These results clearly demonstrate that mutations at the COMT gene give a brown midrib3 phenotype. Thus, the gene genetically recognized as bm3 is the same as the one coding for COMT.