HD-Zip II transcription factors control distal stem cell fate in Arabidopsis roots by linking auxin signaling to the FEZ/SOMBRERO pathway

In multicellular organisms, specialized tissues are generated by specific populations of stem cells through cycles of asymmetric cell divisions, where one daughter undergoes differentiation and the other maintains proliferative properties. In Arabidopsis thaliana roots, the columella - a gravity-sensing tissue that protects and defines the position of the stem cell niche - represents a typical example of a tissue whose organization is exclusively determined by the balance between proliferation and differentiation. The columella derives from a single layer of stem cells through a binary cell fate switch that is precisely controlled by multiple, independent regulatory inputs. Here, we show that the HD-Zip II transcription factors (TFs) HAT3, ATHB4 and AHTB2 redundantly regulate columella stem cell fate and patterning in the Arabidopsis root. The HD-Zip II TFs promote columella stem cell proliferation by acting as effectors of the FEZ/SMB circuit and, at the same time, by interfering with auxin signaling to counteract hormone-induced differentiation. Overall, our work shows that HD-Zip II TFs connect two opposing parallel inputs to fine-tune the balance between proliferation and differentiation in columella stem cells.

Incremental net benefit of wearable devices for home monitoring of chronically ill patients

Background

Hospital overcrowding is a growing problem worldwide. Studies demonstrated that up to 40% to 67% of hospitalizations of residents in nursing homes may be avoidable, causing health and economic damages. Furthermore, research shows that for non-critical patients there are arguably no differences between home and hospital recovery in terms of health outcomes, with a preference for home settings in most patients. During COVID-19 pandemic, telemedicine and homecare increased its range of possible intervention, allowing efficient and cost-effective processes of care. Transdermal sensors are indeed a cheap and easy to use alternative to conventional instruments, allowing a continuously operative and ready-to-use tool to care providers. This systematic review aims to map the application fields of these technologies, demonstrating their accuracy and assessing their cost-effectiveness in chronically ill home-assisted patients.

Methods

Articles were retrieved from Scopus, Web of Science, and PubMed. The dominance ranking matrix (DRM) tool was applied to allow a qualitative synthesis of the studies. Incremental net benefits (INBs) were estimated and meta-analysis was implemented to pool INBs across studies. A comparison between wearables and conventional tools accuracy was simultaneously carried out through a literature review.

Results

The database search identified 1156 publications of which six articles were considered eligible for the meta-analysis. According to DRM, 80% of evaluated studies showed the cost-effectiveness of wearable devices. The pooled INB of wearables over conventional measurement was estimated at US$1280 (95% CI US$952 - US$2849). In 85% of evaluated wearables the accuracy resulted comparable to conventional measurement tools.

Conclusions

Wearables performances resulted as accurate as conventional methods and their application cost-effective. A continuous measurement of parameters may relate to a better process of care for chronically ill outpatients.

Key messages

• Wearables are a cheap and accurate alternative to conventional life parameters measurement tools.

• Technology evolution might soon reduce the pressure on hospitals, changing the care process of chronically ill outpatients allowing continuous evaluation of their health status.

Algorithms and Artificial Intelligence in Primary Care for conscious drug use: a systematic review

 

Primary care is a growing medical field willing to become a more integrated and technological asset. Although big changes already happened and more investments have been made, a limited amount of literature describes processes and technologies there applied or to be used. This paper aims to evaluate the efficacy and usability of different types of algorithms in primary care to improve drug safety by speeding up processes and achieving greater accuracy opening the path to providing better healthcare overall. The PICO model was adopted, three electronic databases (PubMed, Cochrane, Web of Science) were searched using appropriate keywords. Selected studies were assessed for quality and risk of bias using the National Institutes of Health Quality Assessment of Controlled Intervention Studies. Data were analysed using descriptive statistic, comparison of drug usage between algorithms or artificial intelligence application and usual care was performed using a χ2 test(α = 0.05). Out of 2207,19 studies were included,37% of them regarding error prevention,21% drug interactions,21% drug monitoring,16% drug prescription,5% drug administration. Results showed an easier and safer medication use in 74% of studies, a loss of safeness and accuracy in 16%; 10% of total studies did not come up with a valid esteem of results either for inadequate availability of the AI machine or because of the heterogeneity of the results in different settings. The evaluation of errors prevention, 40% of total studies, showed the most statistically significant results with 88% of positive outcomes from AI application. The results support that this technological approach to drugs management could contribute to the safety of treatment and to increase patients' and general practitioners' satisfaction. The application of AI or algorithms is significantly associated with a reduction of drug use errors (p < 0.05). Future studies should work toward establishing a gold standard to measure AI performances.

Key messages

Artificial Intelligence and Algorithms in primary care have the potentiality to disrupt patient care with a safer and faster medication management. A comparison between Artificial Intelligence or algorithms and standard clinical practice may help finding the medication fields where a technological support could lead to better results.

[Fragility in a Public Health perspective: principles and tools for a "life course" approach prevention- oriented]

The Covid-19 pandemic significantly increased the workload for the Italian Health Service. There is few information in the literature on the pediatric population and on the management of pediatric hospitals. The aim of this article is to describe the management of healthcare services during Covid-19 emergency in Regina Margherita Children's Hospital. The Regina Margherita Children's Hospital is specialized in the prevention, diagnosis and treatment of pediatric diseases. About 1000 health worker work in this Hospital and 278 hospitalization places are available.

Renewing primary care: the bottom-up experience of an Italian health professional movement

Sustainability of the National Health Systems (NHS) has been facing different challenges. A community-oriented Comprehensive Primary Health Care (CommOr C-PHC) could help its survival. Such a framework, focused on health promotion, primary prevention, not communicable disease management, requires new capabilities among health professionals. Considering teamwork and interprofessional collaboration (IPC) as PHC core elements, there is growing recognition of the need of interprofessional education (IPE). Nevertheless, italian medical education is distant from other disciplines and mainly based on hospital care settings. Since this situation represents an obstacle to implement a CommOr C-PHC model of health service, new ways of training students and retraining actual health workers should be developed.

The aim of the project is to design IPE programs and to improve IPC within the C-PHC framework, shared learning environments placed in the community were developed.

At the end of 2017 a group of young italian health professionals (public health resident, young general practitioner, social assistant, nurse, medical anthropologist, etc) founded the Campaign “2018 Primary Health care: Now or never”, a cultural movement of public health advocacy. Its goals are: The creation of a common cultural background through the study of PHC evidence and best italian and international practices. Organization of workshops all over Italy: peer education training session, site-visits, lectures with Italian and foreigner health professionals, based on need assessment methods.

Individuation of learning environments placed in the community and in a primary care setting where students can apprehend social determinants of health, exercise critical thinking and develop transprofessional knowledge.

Key messages

Young health professionals from Italy, starting from the need for a different educational framework, based on IPE, created a movement to defend the NHS and promote PHC principles. The success and large participation of a national campaign sustaining PHC and aimed at promoting interprofessional education shows the need for a change in the medical education field.

A public health Italian ethical movement to sustain the beveridge model: health promotion and equity

Worldwide sustainability of the National Health Systems (NHS) has been facing different challenges, such as population ageing, epidemiologic transition and deep social transformations. All these changes are struggling Italian welfare state and its public NHS. Following the principle of the Right to Health of the Declaration of Human Right and the Italian Constitution, a group of young health professionals from all over Italy founded a campaign called “2018 Primary Health care: Now or Never”(PHC Campaign) reminding WHO report of 2008 “primary Health Care: Now more than never”. This movement promotes a reform of the NHS focusing on comprehensive-PHC (C-PHC) and health promotion to guarantee sustainability of the Beveridge model italian system, fight health inequalities and answer the complexity of population needs in a period of spending cuts.

Since the beginning, the movement started an educational program through the study of the literature and the research of the Italian and international best practices of C-PHC and community health promotion. As a result, to achieve the goal of this project, PHC campaign organized peer education training sessions, educational site-visit of some Italian best practices, lectures and workshops with Italian and foreigner health professionals experts on the field. Several national and regional events had been organized all over Italy. Members of “PHC” Campaign have been invited to write books, news on web-based newspapers on this topic and participate in congresses. To date, PHC campaign might be considered one of the strongest not-institutional voices in Italy in supporting the public beveridge-model NHS

Moved from a strong ethical health policy view underlined the importance of the Right-to-Health and of a C-PHC based NHS, since the beginning, “2018 Primary Health care: Now or Never” Movement identified three asset of action: advocacy, education/knowledge and diffusion.

Key messages

The experience showed the importance of health professionals engagement in public health topics such as sustainability of public NHS in order to promote a reform towards health promotion and equity. PHC Campaign is an example of how a bottom-up ethical movement on public health from different Health professionals could actively contribute to promoting cultural and health policy change.

Multiple Links between HD-Zip Proteins and Hormone Networks

HD-Zip proteins are unique to plants, and contain a homeodomain closely linked to a leucine zipper motif, which are involved in dimerization and DNA binding. Based on homology in the HD-Zip domain, gene structure and the presence of additional motifs, HD-Zips are divided into four families, HD-Zip I–IV. Phylogenetic analysis of HD-Zip genes using transcriptomic and genomic datasets from a wide range of plant species indicate that the HD-Zip protein class was already present in green algae. Later, HD-Zips experienced multiple duplication events that promoted neo- and sub-functionalizations. HD-Zip proteins are known to control key developmental and environmental responses, and a growing body of evidence indicates a strict link between members of the HD-Zip II and III families and the auxin machineries. Interactions of HD-Zip proteins with other hormones such as brassinolide and cytokinin have also been described. More recent data indicate that members of different HD-Zip families are directly involved in the regulation of abscisic acid (ABA) homeostasis and signaling. Considering the fundamental role of specific HD-Zip proteins in the control of key developmental pathways and in the cross-talk between auxin and cytokinin, a relevant role of these factors in adjusting plant growth and development to changing environment is emerging.

Outcomes of the calcaneo-stop procedure for the treatment of juvenile flatfoot in young athletes

PURPOSE

Flexible flatfoot (FFF) is a widespread condition in juvenile patients. If symptomatic, FFF can require surgical treatment. The calcaneo-stop procedure has shown excellent clinical and radiographic outcomes and low rates of complications. The aim of the present study was to assess the sport practice of young athletes affected by FFF having undergone the calcaneo-stop procedure.

METHODS

Between 2008 and 2016, 68 sport practitioners were bilaterally treated by the calcaneo-stop procedure, for a total of 136 FFF cases. Clinical evaluation, including the American Orthopedic Foot and Ankle Score (AOFAS), the Yoo et al score and The Foot & Ankle Disability Index (FADI) and FADI Sport scores were assessed. Radiographic evaluation was based on measurement of talar declination, Costa-Bertani's angle and calcaneal pitch.

RESULTS

Mean follow-up was 57.6 months (sd 16.8). The AOFAS score mean increased from 79.3 (sd 5.7) to 97.3 (sd 4.5) three years after surgery. The Yoo score improved from 3.1 (sd 1.0) preoperatively to 11.7 (sd 0.6) three years after surgery. The FADI Sport subscale mean improved from 74.1 (sd 10.4) preoperatively to 95.9 (sd 4.9) three years after surgery.Costa-Bertani's angle decreased from 156.1° (sd 4.2°) to 135.8° (sd 7.3°) at three years postoperatively; mean talar declination angle decreased from 44.2° (sd 6.3°) to 30.6° (sd 3.2°) at three years postoperatively and mean calcaneal pitch increased from 12.6° (sd 2.3°) to 16.3° (sd 1.3°) at three years postoperatively.

CONCLUSION

Adolescent patients who underwent the calcaneo-stop procedure reported satisfactory outcomes in terms of clinical and radiological evaluations. Moreover, our results showed an improvement of sport activity levels, with patients recovering sports activity within three months of surgery and without limitation in the execution of preferred activities.

LEVEL OF EVIDENCE

IV.

Arabidopsis HD-Zip II proteins regulate the exit from proliferation during leaf development in canopy shade

The shade avoidance response is mainly evident as increased plant elongation at the expense of leaf and root expansion. Despite the advances in understanding the mechanisms underlying shade-induced hypocotyl elongation, little is known about the responses to simulated shade in organs other than the hypocotyl. In Arabidopsis, there is evidence that shade rapidly and transiently reduces the frequency of cell division in young first and second leaf primordia through a non-cell-autonomous mechanism. However, the effects of canopy shade on leaf development are likely to be complex and need to be further investigated. Using combined methods of genetics, cell biology, and molecular biology, we uncovered an effect of prolonged canopy shade on leaf development. We show that persistent shade determines early exit from proliferation in the first and second leaves of Arabidopsis. Furthermore, we demonstrate that the early exit from proliferation in the first and second leaves under simulated shade depends at least in part on the action of the Homeodomain-leucine zipper II (HD-Zip II) transcription factors ARABIDOPSIS THALIANA HOMEOBOX2 (ATHB2) and ATHB4. Finally, we provide evidence that the ATHB2 and ATHB4 proteins work in concert. Together the data contribute new insights on the mechanisms controlling leaf development under canopy shade.

Multiple Pathways in the Control of the Shade Avoidance Response

To detect the presence of neighboring vegetation, shade-avoiding plants have evolved the ability to perceive and integrate multiple signals. Among them, changes in light quality and quantity are central to elicit and regulate the shade avoidance response. Here, we describe recent progresses in the comprehension of the signaling mechanisms underlying the shade avoidance response, focusing on Arabidopsis, because most of our knowledge derives from studies conducted on this model plant. Shade avoidance is an adaptive response that results in phenotypes with a high relative fitness in individual plants growing within dense vegetation. However, it affects the growth, development, and yield of crops, and the design of new strategies aimed at attenuating shade avoidance at defined developmental stages and/or in specific organs in high-density crop plantings is a major challenge for the future. For this reason, in this review, we also report on recent advances in the molecular description of the shade avoidance response in crops, such as maize and tomato, and discuss their similarities and differences with Arabidopsis.

NORMAL NUTRITIONAL COMPONENTS AND EFFECTS ON BONE METABOLISM IN PREVENTION OF OSTEOPOROSIS

Osteoporosis is the most common bone disease, affecting millions of people and causing a high risk of fractures and a loss of quality of life. It is characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. A primary method of prevention, in order to reduce the risk of fractures, is represented by an appropriate lifestyle and a correct diet. There are potentially numerous nutrients and dietary components that can influence bone health, and these range from macronutrients to micronutrients as well as bioactive food ingredients. The purpose of this review is to overview osteoporosis, including its definition, etiology, and incidence, and then provide some information on possible dietary strategies for optimizing bone health and preventing osteoporosis. A correct diet to prevent osteoporosis should contain adequate amounts of calcium, vitamins D and K, protein, and fatty acids. The effects of these elements are briefly discussed, reporting on their correlation with bone benefits.

Performance of the CLS Spotorno uncemented stem in the third decade after implantation

In 2012 we reviewed a consecutive series of 92 uncemented THRs performed between 1986 and 1991 at our institution using the CLS Spotorno stem, in order to assess clinical outcome and radiographic data at a minimum of 21 years. The series comprised 92 patients with a mean age at surgery of 59.6 years (39 to 77) (M:F 43;49). At the time of this review, seven (7.6%) patients had died and two (2.2%) were lost to follow-up. The 23-year Kaplan-Meier survival rates were 91.5% (95% confidence intervals (CI) 85.4% to 97.6%; 55 hips at risk) and 80.3% (95% CI, 71.8% to 88.7%; 48 hips at risk) respectively, with revision of the femoral stem or of any component as endpoints. At the time of this review, 76 patients without stem revision were assessed clinically and radiologically (mean follow-up 24.0 years (21.5 to 26.5)). For the 76 unrevised hips the mean Harris hip score was 87.1 (65 to 97). Femoral osteolysis was detected in five hips (6.6%) only in Gruen zone 7. Undersized stems were at higher risk of revision owing to aseptic loosening (p = 0.0003). Patients implanted with the stem in a varus position were at higher risk of femoral cortical hypertrophy and thigh pain (p = 0.0006 and p = 0.0007, respectively). In our study, survival, clinical outcome and radiographic data remained excellent in the third decade after implantation. Nonetheless, undersized stems were at higher risk of revision owing to aseptic loosening.

Congenital idiopathic talipes equinovarus: an evaluation in infants treated by the Ponseti method

BACKGROUND

Congenital talipes equinovarus (CTEV) is a common but still not fully understood disorder of the lower limb. It is usually defined as a fixation of the foot in adduction, supination, and varus. Different treatment options exist including the Ponseti method.

AIM

We report here the results obtained in infants with CTEV treated by the Ponseti method.

PATIENTS AND METHODS

Eighty two patients (114 clubfeet) were enrolled at the Orthopaedic Clinic of Catania University during the period of March 2004 to January 2010 and followed prospectively up to February 2011: 56 patients (68.29%) were male, the anomaly was bilateral in 32 (39%) cases, unilateral in 50 (60.9%) in the right side in 28 (56%). The mean age at initiation of treatment was 14 days (range 3-81 days), severity of the club foot deformity by the Pirani Severity score was 5.56 points (range 4.3-6 points). Total numbers of Ponseti casts before tenotomy, details of tenotomy, and compliance with CTEV brace were recorded. Clinical evaluation was performed using the functional Ponseti Scoring System. Mean follow up was 4 years: range 13-83 months.

RESULTS

An average of 6.6 casts was necessary before performing the tenotomy. Tenotomy was performed by a single surgeon (V.P.) in a total of 68 patients (82.93%) always in an operating room under general anaesthesia by a percutaneous approach at a mean age of 106 days (range 45-213 days). Compliance with CTEV brace was satisfactory in 79 patients (96.3%). Functional Ponseti Scores were good/excellent in 79 (96.34%) patients (109 clubfeet; 95.61%). Only 3 patients; 3.7% (5 clubfeet; 4.4%) suffered relapse. Poor compliance with the Denis Browne splint was thought to be the main cause of failure.

CONCLUSIONS

The Ponseti method provides an excellent outcome at follow up in the treatment of congenital idiopathic clubfoot.

The bHLH proteins BEE and BIM positively modulate the shade avoidance syndrome in Arabidopsis seedlings

The shade avoidance syndrome (SAS) refers to a set of plant responses initiated after perception by the phytochromes of light with a reduced red to far-red ratio, indicative of vegetation proximity or shade. These responses, including elongation growth, anticipate eventual shading from potential competitor vegetation by overgrowing neighboring plants or flowering to ensure production of viable seeds for the next generation. In Arabidopsis thaliana seedlings, the SAS includes dramatic changes in gene expression, such as induction of PHYTOCHROME RAPIDLY REGULATED 1 (PAR1), encoding an atypical basic helix-loop-helix (bHLH) protein that acts as a transcriptional co-factor to repress hypocotyl elongation. Indeed, PAR1 has been proposed to act fundamentally as a dominant negative antagonist of conventional bHLH transcription factors by forming heterodimers with them to prevent their binding to DNA or other transcription factors. Here we report the identification of PAR1-interacting factors, including the brassinosteroid signaling components BR-ENHANCED EXPRESSION (BEE) and BES1-INTERACTING MYC-LIKE (BIM), and characterize their role as networked positive regulators of SAS hypocotyl responses. We provide genetic evidence that these bHLH transcriptional regulators not only control plant growth and development under shade and non-shade conditions, but are also redundant in the control of plant viability. Our results suggest that SAS responses are initiated as a consequence of a new balance of transcriptional regulators within the pre-existing bHLH network triggered by plant proximity, eventually causing hypocotyls to elongate.

Dynamics of the shade-avoidance response in Arabidopsis

Shade-intolerant plants perceive the reduction in the ratio of red light (R) to far-red light (FR) as a warning of competition with neighboring vegetation and display a suite of developmental responses known as shade avoidance. In recent years, major progress has been made in understanding the molecular mechanisms underlying shade avoidance. Despite this, little is known about the dynamics of this response and the cascade of molecular events leading to plant adaptation to a low-R/FR environment. By combining genome-wide expression profiling and computational analyses, we show highly significant overlap between shade avoidance and deetiolation transcript profiles in Arabidopsis (Arabidopsis thaliana). The direction of the response was dissimilar at the early stages of shade avoidance and congruent at the late ones. This latter regulation requires LONG HYPOCOTYL IN FAR RED1/SLENDER IN CANOPY SHADE1 and phytochrome A, which function largely independently to negatively control shade avoidance. Gene network analysis highlights a subnetwork containing ELONGATED HYPOCOTYL5 (HY5), a master regulator of deetiolation, in the wild type and not in phytochrome A mutant upon prolonged low R/FR. Network analysis also highlights a direct connection between HY5 and HY5 HOMOLOG (HYH), a gene functionally implicated in the inhibition of hypocotyl elongation and known to be a direct target of the HY5 transcription factor. Kinetics analysis show that the HYH gene is indeed late induced by low R/FR and that its up-regulation depends on the action of HY5, since it does not occur in hy5 mutant. Therefore, we propose that one way plants adapt to a low-R/FR environment is by enhancing HY5 function.

TGF-β1 exposure induces epithelial to mesenchymal transition both in CSCs and non-CSCs of the A549 cell line, leading to an increase of migration ability in the CD133+ A549 cell fraction

Metastasis is the leading cause of death by cancer. Non-small-cell lung cancer (NSCLC) represents nearly 85% of primary malignant lung tumours. Recent researches have demonstrated that epithelial-to-mesenchymal transition (EMT) plays a key role in the early process of metastasis of cancer cells. Transforming growth factor-β1 (TGF-β1) is the major inductor of EMT. The aim of this study is to investigate TGF-β1's effect on cancer stem cells (CSCs) identified as cells positive for CD133, side population (SP) and non-cancer stem cells (non-CSCs) identified as cells negative for CD133, and SP in the A549 cell line. We demonstrate that TGF-β1 induces EMT in both CSC and non-CSC A549 sublines, upregulating the expression of mesenchymal markers such as vimentin and Slug, and downregulating levels of epithelial markers such as e-cadherin and cytokeratins. CSC and non-CSC A549 sublines undergoing EMT show a strong migration and strong levels of MMP9 except for the CD133(-) cell fraction. OCT4 levels are strongly upregulated in all cell fractions except CD133(-) cells. On the contrary, wound size reveals that TGF-β1 enhances motility in wild-type A549 as well as CD133(+) and SP(+) cells. For CD133(-) and SP(-) cells, TGF-β1 exposure does not change the motility. Finally, assessment of growth kinetics reveals major colony-forming efficiency in CD133(+) A549 cells. In particular, SP(+) and SP(-) A549 cells show more efficiency to form colonies than untreated corresponding cells, while for CD133(-) cells no change in colony number was observable after TGF-β1 exposure. We conclude that it is possible to highlight different cell subpopulations with different grades of stemness. Each population seems to be involved in different biological mechanisms such as stemness maintenance, tumorigenicity, invasion and migration.

Arabidopsis HD-Zip II transcription factors control apical embryo development and meristem function

The Arabidopsis genome encodes ten Homeodomain-Leucine zipper (HD-Zip) II proteins. ARABIDOPSIS THALIANA HOMEOBOX 2 (ATHB2), HOMEOBOX ARABIDOPSIS THALIANA 1 (HAT1), HAT2, HAT3 and ATHB4 are regulated by changes in the red/far red light ratio that induce shade avoidance in most of the angiosperms. Here, we show that progressive loss of HAT3, ATHB4 and ATHB2 activity causes developmental defects from embryogenesis onwards in white light. Cotyledon development and number are altered in hat3 athb4 embryos, and these defects correlate with changes in auxin distribution and response. athb2 gain-of-function mutation and ATHB2 expression driven by its promoter in hat3 athb4 result in significant attenuation of phenotypes, thus demonstrating that ATHB2 is functionally redundant to HAT3 and ATHB4. In analogy to loss-of-function mutations in HD-Zip III genes, loss of HAT3 and ATHB4 results in organ polarity defects, whereas triple hat3 athb4 athb2 mutants develop one or two radialized cotyledons and lack an active shoot apical meristem (SAM). Consistent with overlapping expression pattern of HD-Zip II and HD-Zip III gene family members, bilateral symmetry and SAM defects are enhanced when hat3 athb4 is combined with mutations in PHABULOSA (PHB), PHAVOLUTA (PHV) or REVOLUTA (REV). Finally, we show that ATHB2 is part of a complex regulatory circuit directly involving both HD-Zip II and HD-Zip III proteins. Taken together, our study provides evidence that a genetic system consisting of HD-Zip II and HD-Zip III genes cooperates in establishing bilateral symmetry and patterning along the adaxial-abaxial axis in the embryo as well as in controlling SAM activity.

Colonization and movement of GFP-labeled Clavibacter michiganensis subsp. michiganensis during tomato infection

The vascular pathogen Clavibacter michiganensis subsp. michiganensis is responsible for bacterial wilt and canker of tomato. Pathogenicity of this bacterium is dependent on plasmid-borne virulence factors and serine proteases located on the chromosomal chp/tomA pathogenicity island (PAI). In this study, colonization patterns and movement of C. michiganensis subsp. michiganensis during tomato infection was examined using a green fluorescent protein (GFP)-labeled strain. A plasmid expressing GFP in C. michiganensis subsp. michiganensis was constructed and found to be stable in planta for at least 1 month. Confocal laser-scanning microscopy (CLSM) of inoculated stems showed that the pathogen extensively colonizes the lumen of xylem vessels and preferentially attaches to spiral secondary wall thickening of the protoxylem. Acropetal movement of the wild-type strain C. michiganensis subsp. michiganensis NCPPB382 (Cmm382) in tomato resulted in an extensive systemic colonization of the whole plant reaching the apical region after 15 days, whereas Cmm100 (lacking the plasmids pCM1 and pCM2) or Cmm27 (lacking the chp/tomA PAI) remained confined to the area surrounding of the inoculation site. Cmm382 formed biofilm-like structures composed of large bacterial aggregates on the interior of xylem walls as observed by CLSM and scanning electron microscopy. These findings suggest that virulence factors located on the chp/tomA PAI or the plasmids are required for effective movement of the pathogen in tomato and for the formation of cellular aggregates.

Plant adaptation to dynamically changing environment: the shade avoidance response

The success of competitive interactions between plants determines the chance of survival of individuals and eventually of whole plant species. Shade-tolerant plants have adapted their photosynthesis to function optimally under low-light conditions. These plants are therefore capable of long-term survival under a canopy shade. In contrast, shade-avoiding plants adapt their growth to perceive maximum sunlight and therefore rapidly dominate gaps in a canopy. Daylight contains roughly equal proportions of red and far-red light, but within vegetation that ratio is lowered as a result of red absorption by photosynthetic pigments. This light quality change is perceived through the phytochrome system as an unambiguous signal of the proximity of neighbors resulting in a suite of developmental responses (termed the shade avoidance response) that, when successful, result in the overgrowth of those neighbors. Shoot elongation induced by low red/far-red light may confer high relative fitness in natural dense communities. However, since elongation is often achieved at the expense of leaf and root growth, shade avoidance may lead to reduction in crop plant productivity. Over the past decade, major progresses have been achieved in the understanding of the molecular basis of shade avoidance. However, uncovering the mechanisms underpinning plant response and adaptation to changes in the ratio of red to far-red light is key to design new strategies to precise modulate shade avoidance in time and space without impairing the overall crop ability to compete for light.

Sequential expression of bacterial virulence and plant defense genes during infection of tomato with Clavibacter michiganensis subsp. michiganensis

The molecular interactions between Clavibacter michiganensis subsp. michiganensis and tomato plant were studied by following the expression of bacterial virulence and host-defense genes during early stages of infection. The C. michiganensis subsp. michiganensis genes included the plasmid-borne cellulase (celA) and the serine protease (pat-1), and the serine proteases chpC and ppaA, residing on the chp/tomA pathogenicity island (PAI). Gene expression was measured following tomato inoculation with Cmm382 (wild type), Cmm100 (lacking the plasmids pCM1 and pCM2), and Cmm27 (lacking the PAI). Transcriptional analysis revealed that celA and pat-1 were significantly induced in Cmm382 at initial 12 to 72 h, whereas chpC and ppaA were highly expressed only 96 h after inoculation. Interdependence between the expression of chromosomal and of plasmid-located genes was revealed: expression of celA and pat-1 was substantially reduced in the absence of the chp/tomA PAI, whereas chpC and ppaA expressions were reduced in the absence of the virulence plasmids. Transcription of chromosomal genes involved in cell wall degradation (i.e., pelA1, celB, xysA, and xysB), was also induced at early stages of infection. Expression of the host-defense genes, chitinase class II and pathogenesis-related protein-5 isoform was induced in the absence of the PAI at early stages of infection, suggesting that PAI-located genes are involved in suppression of tomato basal defenses.

The Arabidopsis homeodomain-leucine zipper II gene family: diversity and redundancy

The Arabidopsis genome contains 10 genes belonging to the HD-Zip II family including ATHB2 and HAT2. Previous work has shown that ATHB2 is rapidly and strongly induced by light quality changes that provoke the shade avoidance response whereas HAT2 expression responds to auxin. Here, we present a genome-wide analysis of the HD-Zip II family. Phylogeny reconstruction revealed that almost all of the HD-Zip II genes can be subdivided into 4 clades (alpha-delta), each clade comprising 2-3 paralogs. Gene expression studies demonstrated that all the gamma and delta genes are regulated by light quality changes. Kinetics of induction, low R/FR/high R/FR reversibility and auxin response analyses strongly suggested that HAT1, HAT3 and ATHB4, as ATHB2, are under the control of the phytochrome system whereas HAT2 is up-regulated by low R/FR as a consequence of the induction of the auxin signaling pathway provoked by FR-rich light. Root and shoot digital in situ revealed that gamma and delta genes are also tightly regulated during plant development with both distinct and overlapping patterns. Phenotypes of gain of function and dominant negative lines demonstrated that one or more of the HD-Zip II gamma genes negatively regulate cell proliferation during leaf development in a high R/FR light environment. Finally, target gene analysis using a chimeric transcription factor (HD-Zip2-V-G), known to activate ATHB2 target genes in a glucocorticoid-dependent manner, revealed that all the 10 HD-Zip II genes can be recognized by the HD-Zip 2 domain in vivo, implying an intricate negative feedback network.

A novel regulatory circuit underlying plant response to canopy shade

A plant growing in the field has the unique ability to sense the presence of other plants growing near by and adjust its growth rate accordingly. This ability to detect neighbors, which is referred to as shade avoidance response, is mediated by members of the phytochrome family which detect light in the red (R) and far-red (FR) region of the spectrum. Work done by several laboratories has shown that low R/FR provides the signal for shade avoidance response during which the elongation of stem-like organs occurs at the expense of leaf development. However, the mechanism by which the low R/FR signal is transduced to attenuate leaf development has remained largely unknown. In the August issue of Genes and Development, we have shown that low R/FR rapidly and transiently arrests the growth of the leaf primordium. By exploiting mutant analysis in combination with genome wide expression profiling, we have identified a novel regulatory circuit underlying plant response to canopy shade. Together, the data demonstrate that the growth arrest induced by low R/FR depends on auxin-induced cytokinin breakdown in pre-procambial cells of developing primordia. In this addendum, we discuss open questions to be addressed in the future.

Canopy shade causes a rapid and transient arrest in leaf development through auxin-induced cytokinin oxidase activity

A plant grown under canopies perceives the reduction in the ratio of red (R) to far-red (FR) light as a warning of competition, and enhances elongation growth in an attempt to overgrow its neighbors. Here, we report that the same low R/FR signal that induces hypocotyl elongation also triggers a rapid arrest of leaf primordium growth, ensuring that plant resources are redirected into extension growth. The growth arrest induced by low R/FR depends on auxin-induced cytokinin breakdown in incipient vein cells of developing primordia, thus demonstrating the existence of a previously unrecognized regulatory circuit underlying plant response to canopy shade.

Functional analysis of transcription factors by microparticle bombardment

This chapter describes a method for rapid gene expression assays in Arabidopsis. Three distinct plasmids are codelivered into leaves by microparticle bombarment. The first one carries a transacting factor gene driven by the cauliflower mosaic virus (CaMV) 35S promoter. The second plasmid includes a reporter luciferase (LUC) gene transcribed from a promoter containing the TF binding site(s). The third plasmid contains a reference beta-glucuronidase (GUS) gene transcribed from the 35S-CaMV promoter, which is used to normalize data derived from independent experiments. This method could be applied to study systematically the functional properties of Arabidopsis transcription factors as well as to identify promoters and control region(s) regulated by specific transcription factors.

A dynamic balance between gene activation and repression regulates the shade avoidance response in Arabidopsis

Plants grown under dense canopies perceive through the phytochrome system a reduction in the ratio of red to far-red light as a warning of competition, and this triggers a series of morphological changes to avoid shade. Several phytochrome signaling intermediates acting as positive regulators of accelerated elongation growth and induction of flowering in shade avoidance have been identified. Here we report that a negative regulatory mechanism ensures that in the presence of far-red-rich light an exaggerated plant response does not occur. Strikingly, this unpredicted negative regulatory mechanism is centrally involved in the attenuation of virtually all plant responses to canopy shade.

Riluzole restores motor activity in rats with post-traumatic peripheral neuropathy

Riluzole is a presynaptic inhibitor of glutamate release with neuroprotective properties. In order to evaluate the effects of riluzole on motor activity in post-traumatic peripheral neuropathy (PTPN), the sciatic nerve of Wistar male rats was exposed monolaterally and subjected to crushing for one min by a surgical forceps. Animals received an intraperitoneal treatment with riluzole (2, 4 or 8 mg/kg per day), diclofenac (5, 10 or 20 mg/kg) or with vehicle for 3 days. Motor activity and coordination was evaluated in a circular open field and in the rotorod test. The treatment with riluzole stimulated ambulation in PTPN rats and improved their motor performance and coordination. The effect of treatment with riluzole on locomotor activity was greater than that of treatment with diclofenac and was dose-dependent. Furthermore, in contrast to vehicle- and diclofenac-treated rats, animals treated with riluzole showed a long-lasting improvement of locomotor activity as it was assessed 7 days after the end of treatment. These findings suggest that riluzole may improve motor performance in PTPN, and this does not depend on its antinociceptive activity. Its neuroprotective properties are possibly involved in this effect.

Heterotopic ossification after total hip replacement and the HLA system in the Sicilian population

Heterotopic ossification (HO) is a frequent complication following total hip arthroplasty (THA). At present, the etiology HO is unknown, however, genetic predisposition may be a cause of HO in individuals in whom no risk factors can be detected. The goal of this study was to investigate the HLA system, searching for any correlation with the presence of HO after THA. Thirty-five patients of Sicilian origin were operated on between January 1997 and January 1999 for cementless THA under regional anesthesia. The entire series was divided into three groups and all underwent histocompatibility typing. Group I was made up of 10 patients who presented with HO Brooker grades 1 and 2 after THA; group 2 comprised 7 patients affected by grades 3 and 4 HO after THA; and group 3 was made up of 18 subjects who presented with one or more preoperative risk factors for developing peri-prosthetic HO before undergoing THA. No positivity for HLA-B27 antigen was observed, but there was as an increase in HLA-B18 (with respect to that in the Sicilian population) in patients with HO following THA. The main conclusion from the study is that there is a strong correlation between the presence of the antigens HLA-A2 and HLA-B18 in patients with HO grades 3 and 4.

Innate immunity in plants

Studies of receptors and signal-transduction components that play a role in plant disease resistance have revealed remarkable similarities with innate immunity pathways in insects and mammals. In plants, specific receptors encoded by disease-resistance genes interact with products of microbial effector genes to activate defence responses. Resistance proteins have been found to have motifs in common with components of immune response pathways in mammals and invertebrates, and to rely on similar downstream signalling components. In the future, the sharing of ideas among plant and animal biologists is likely to broaden our understanding of defence responses in diverse organisms.

Signal recognition and transduction mediated by the tomato Pto kinase: a paradigm of innate immunity in plants

Plant disease resistance is the result of an innate host defense mechanism, which relies on the ability of the plant to recognize pathogen invasion and to efficiently mount defense responses. In tomato, resistance to the pathogen Pseudomonas syringae is mediated by the specific interaction between the plant serine/threonine kinase Pto and the bacterial protein AvrPto. This article reviews molecular and biochemical properties that confer to Pto the capability to function as an intracellular receptor and to activate a signaling cascade leading to the induction of defense responses.

Subjects positive for hepatitis C virus RNA with normal aminotransferase levels, a "trompe l'oeil" clinical picture?

BACKGROUND

Quite often subjects affected by chronic hepatitis C virus infection have no clinical signs of liver disease and serum aminotransferase values never go beyond the upper limit of normal. Yet these subjects, defined "asymptomatic HCV carriers", often have active viral replication and various degrees of histological damage.

AIMS

To verify, in a population of antibody to hepatitis C virus carriers, if normal serum aminotransferase values in hepatitis C virus-RNA positive differed considerably from those in hepatitis C virus-RNA negative subjects.

SUBJECTS/METHODS

We followed 24 anti-hepatitis C virus-positive subjects (15 hepatitis C virus-RNA positive and 9 negative) by measuring alanine and aspartate aminotransferase levels at 3-month intervals for a median of 40 months (range 6-77).

RESULTS

Determinations resulted repeatedly and rigorously within the normal range in all participants. Alanine aminotransferase values were higher in hepatitis C virus-RNA positives than in negatives (mean +/- SD: 0.609+/-0.172 vs 0.434+/-0.153 times the upper limit of normal; p<O.001). Aspartate aminotransferase values in both groups reflected the same consistent difference (mean +/- SD: 0.652+/-0.170 vs 0.528+/-0.151 times the upper limit of normal, p<0.001).

CONCLUSIONS

Our findings demonstrate that biochemical activity exists in asymptomatic hepatitis C virus-RNA-positive carriers, but it is so slight that serum aminotransferase levels do not go beyond the upper limit of normal. With the prevailing range of normality, serum aminotransferase determination is a helpful but not reliable marker of disease activity in chronic hepatitis C virus infection. The normal range for aminotransferases needs to be redefined in order to set up a more accurate diagnostic profile of subjects with chronic hepatitis C virus infection.

Thr38 and Ser198 are Pto autophosphorylation sites required for the AvrPto-Pto-mediated hypersensitive response

The tomato Pto kinase confers resistance to Pseudomonas syringae pv. tomato expressing the AvrPto protein. To elucidate the role of Pto autophosphorylation in disease resistance, eight sites autophosphorylated by Pto in vitro were identified by a combination of HPLC purification of tryptic phosphopeptides, MALDI-TOF/MS analysis and Edman degradation. Mutational analysis of the autophosphorylation sites revealed that Pto residues Thr38 and Ser198 are required for AvrPto-Pto- mediated elicitation of a hypersensitive response in the plant. Thr38, which is the main Pto autophosporylation site and is located outside the kinase catalytic domain, was also required for Pto kinase activity and its physical interaction with AvrPto, the Pti1 kinase and the transcription factor Pti4. Ser198, located in the Pto activation domain, was dispensable for kinase activity and for interaction with AvrPto. However, a mutation at this site resulted in altered Pto interactions with the Pti1 kinase and the Pto interactors of unknown function Pti3 and Pti10. These results suggest that autophosphorylation events at Pto Thr38 and Ser198 are required for signal transduction by Pto and participate in distinct molecular mechanisms.

The major site of the pti1 kinase phosphorylated by the pto kinase is located in the activation domain and is required for pto-pti1 physical interaction

The Pto and Pti1 serine/threonine protein kinases are key components of the signaling pathway leading to speck disease resistance in tomato. The two kinases physically interact in the yeast two-hybrid system, and Pto specifically phosphorylates Pti1 in vitro. In this study, we identified and characterized the major Pti1 site phosphorylated by Pto. Pto was expressed in Escherichia coli as a maltose-binding fusion protein (MBP-Pto), and used to phosphorylate in vitro a kinase deficient Pti1 protein fused to glutathione S-transferase (GST-Pti1[K96N]). The major phosphopeptide derived from trypsin digestion of phosphorylated GST-Pti1(K96N) was partially purified by reverse-phase HPLC and analyzed by matrix assisted laser desorption/ionization mass spectrometry. Its mass corresponded to phosphopeptide LHSTR, which lies in the Pti1 kinase activation domain at amino acid position 230-234. By phosphoamino acid analysis, Thr233 was determined to be the phosphorylation site of peptide LHSTR. Mutations of Thr233 reduced dramatically Pti1 phosphorylation by MBP-Pto and Pti1 autophosphorylation, providing evidence that the same Pti1 site is involved in the two reactions. Moreover, phosphorylation of Thr233 appeared to be required for Pto-Pti1 physical interaction, as a mutation of this site to alanine, but not to aspartate, abolished the interaction between Pto and Pti1 in the yeast two-hybrid system.

The ethylene-inducible PK12 kinase mediates the phosphorylation of SR splicing factors

The tobacco PK12 is induced by the plant hormone ethylene and is a member of the LAMMER family of protein kinases. Members of this family contain in their C-terminus a unique 'EHLAMMERI/VLGPLP' motif of unknown function, and are related to cyclin- and mitogen-activated protein (MAP)-dependent kinases. The animal members of this class play a role in differentiation. They phosphorylate and physically interact with serine/arginine-rich (SR) splicing factors in vivo to alter their activity and the splicing of target mRNAs. SR proteins have been recently described in plants. The capability of PK12 LAMMER kinase to bind and phosphorylate SR proteins was tested in vitro by kinase and binding assays. The tobacco PK12 phosphorylated both animal and plant SR proteins and specifically interacted with the plant splicing factor atSRp34/SR1. In addition, by site-directed mutagenesis, the LAMMER motif was found to be required for PK12 kinase activity but was not necessary for substrate binding. Consistent with a role in phosphorylation of splicing factors, PK12 was found to localize to the nucleus when transiently over-expressed in suspension cells.

Shade avoidance responses are mediated by the ATHB-2 HD-zip protein, a negative regulator of gene expression

The ATHB-2 gene encoding an homeodomain-leucine zipper protein is rapidly and strongly induced by changes in the ratio of red to far-red light which naturally occur during the daytime under the canopy and induce in many plants the shade avoidance response. Here, we show that elevated ATHB-2 levels inhibit cotyledon expansion by restricting cell elongation in the cotyledon-length and -width direction. We also show that elevated ATHB-2 levels enhance longitudinal cell expansion in the hypocotyl. Interestingly, we found that ATHB-2-induced, as well as shade-induced, elongation of the hypocotyl is dependent on the auxin transport system. In the root and hypocotyl, elevated ATHB-2 levels also inhibit specific cell proliferation such as secondary growth of the vascular system and lateral root formation. Consistent with the key role of auxin in these processes, we found that auxin is able to rescue the ATHB-2 lateral root phenotype. We also show that reduced levels of ATHB-2 result in reciprocal phenotypes. Moreover, we demonstrate that ATHB-2 functions as a negative regulator of gene expression in a transient assay. Remarkably, the expression in transgenic plants of a derivative of ATHB-2 with the same DNA binding specificity but opposite regulatory properties results in a shift in the orientation of hypocotyl cell expansion toward radial expansion, and in an increase in hypocotyl secondary cell proliferation. A model of ATHB-2 function in the regulation of shade-induced growth responses is proposed.

Clinical outcome of chronic hepatitis C in patients treated with interferon: comparison between responders and non-responders

AIM

To evaluate the prognosis of chronic hepatitis C in relation to interferon therapy response and the persistence of therapeutic benefits.

PATIENTS/METHODS

We studied the clinical outcome of 191 patients with chronic infection (152 chronic hepatitis C and 39 cirrhosis) treated with recombinant alpha-interferon (3-6 MU on alternate days for 1 year) during a mean period of 47 months (range 22.5-73.8). Control tests were done at 6-month intervals. HCV RNA was determined pre- and post-treatment in all participants, but continued yearly in long-term responders. The appearance of cirrhosis was estimated using a non-invasive method that utilizes a model based on clinical, instrumental and biochemical variables. Ascites, encephalopathy, haemorrhage, hepatocellular carcinoma, and death were considered liver-disease-related events.

RESULTS

A total of 39 patients were long-term responders, 36 relapsers, and 116 non-responders; 92% of long-term responders cleared HCV RNA and remained negative throughout the study period. The 3 HCV-RNA-positive long-term responders continued being so. No biochemical relapse was observed in long-term responders regardless of virological status. New cirrhosis was observed in 3/30 relapsers, in 9/85 non-responders, and in no long-term responders. Overall, 9 episodes of severe events occurred in 20% of cirrhotics and in 0.6% of chronic hepatitis, all non-responders.

CONCLUSIONS

Long-term response interrupts the progression to cirrhosis and reduces the incidence of severe complications. Multivariate analysis revealed that "baseline diagnosis of cirrhosis" was the only independent factor predictive of an unfavourable outcome of chronic HCV-related liver disease.

The Arabidopsis Athb-8, -9 and -14 genes are members of a small gene family coding for highly related HD-ZIP proteins

We report the isolation and characterization of two Arabidopsis homeobox genes highly related to the Athb-8 gene. The full-length cDNAs encode proteins of 841 and 852 amino acids which we have designated Athb-9 and -14, respectively. Athb-8, -9 and -14 are members of a small family of HD-Zip proteins (HD-ZIP III) characterized by a HD-Zip motif confined to the N-terminus of the polypeptide. The spatial organization of the HD-Zip domain of Athb-8, -9 and -14 is different from that of the Athb-1 (a member of the HD-ZIP I family) and Athb-2 (a member of the HD-ZIP II family) HD-Zip domains. DNA binding analysis performed with random-sequence DNA templates showed that the Athb-9 HD-Zip (HD-Zip-9) domain, but not the Athb-9 HD alone, binds to DNA. The HD-Zip-9 domain recognizes a 11 bp pseudopalindromic sequence (GTAAT(G/C)ATTAC), as determined by selecting high-affinity binding sites from random-sequence DNA. Moreover, gel retardation assays demonstrated that the HD-Zip-9 domain binds to DNA as a dimer. These data support the notion that the HD-ZIP III domain interacts with DNA recognition elements in a fashion similar to the HD-ZIP I and II domains.

Recognition specificity for the bacterial avirulence protein AvrPto is determined by Thr-204 in the activation loop of the tomato Pto kinase

The Pto kinase confers resistance in tomato to P. syringae pv. tomato strains expressing the AvrPto protein. Physical interaction of the Pto kinase and AvrPto protein in the plant cell initiates host defense responses. The recognition event between these two proteins is very specific; AvrPto does not interact with other closely related kinases, including the Fen kinase, which shares 80% amino acid identity with Pto. By using Pto-Fen chimeric proteins and site-directed mutagenesis, we found that Thr-204 is required for Pto interaction with AvrPto in a yeast two-hybrid system and for recognition specificity in a tobacco leaf transient assay. Substitution of Thr-204 into the Fen kinase allowed that kinase to interact with AvrPto and to confer an AvrPto-specific defense response in tobacco leaves. Thus, simple mutations appear capable of giving rise to new resistance gene specificities.

Biochemical properties of two protein kinases involved in disease resistance signaling in tomato

In tomato plants, resistance to bacterial speck disease is mediated by a phosphorylation cascade, which is triggered by the specific recognition between the plant serine/threonine protein kinase Pto and the bacterial AvrPto protein. In the present study, we investigated in vitro biochemical properties of Pto, which appears to function as an intracellular receptor for the AvrPto signal molecule. Pto and its downstream effector Pti1, which is also a serine/threonine protein kinase, were expressed in Escherichia coli as maltose-binding protein and glutathione S-transferase fusion proteins, respectively. The two kinases each autophosphorylated at multiple sites as determined by phosphopeptide mapping. In addition, Pto and Pti1 autophosphorylation occurred via an intramolecular mechanism, as their specific activity was not affected by their molar concentration in the assay. Moreover, an active glutathione S-transferase-Pto fusion failed to phosphorylate an inactive maltose-binding protein-Pto(K69Q) fusion excluding an intermolecular mechanism of phosphorylation for Pto. Pti1 phosphorylation by Pto was also characterized and found to occur with a Km of 4.1 microM at sites similar to those autophosphorylated by Pti1. Pto and the product of the recessive allele pto phosphorylated Pti1 at similar sites, as observed by phosphopeptide mapping. This suggests that the inability of the kinase pto to confer resistance to bacterial speck disease in tomato is not caused by altered recognition specificity for Pti1 phosphorylation sites.

Chronic hepatitis C long-term responders to human leukocyte interferon-alpha therapy: persistence of a sustained biochemical and virological response during 5 years of surveillance

OBJECTIVES

To define the biochemical and virological course and IgM response to HCV-core protein in long-term responders (LTRs) during a long surveillance (5 years).

DESIGN

From 1989 to 1991, 98 patients (pts) with biopsy-proven chronic hepatitis C were enrolled into this study. These pts underwent human leukocyte interferon-alpha (LE-IFN alpha) therapy at the prolonged schedule (3 MU thrice weekly for 1 year).

METHODS

Serum alanine-aminotransferases (ALTs) were assessed monthly during and until 1 year after treatment, then every 3 months during the observation period. Qualitative and quantitative HCV RNA and HCV IgM were measured in all pts on baseline samples and in LTRs also after treatment and every following year.

RESULTS

Based on serum ALT course, the pts were defined as: LTRs (14 pts), if their serum ALT levels returned to the normal range during therapy and remained so for at least 1 year afterwards; responders with relapse (RRs, 20 pts), if their serum ALT levels returned to the normal range during therapy but increased after ending treatment; and non-responders (NRs, 64 pts), if their serum ALT levels remained abnormal throughout therapy. No significant differences were seen regarding IgM anti-HCV positivity and serum ALT levels among the three groups. LTRs (12 HCV-RNA negative and two HCV-RNA positive at the end of treatment) maintained their virological status and not one of them experienced an elevation of serum ALT levels throughout the surveillance.

CONCLUSION

Patients affected by chronic hepatitis C and treated with interferon, but who did not experience a biochemical or virological relapse within the first year of follow-up would not relapse later on; thus, we are able to conclude that these subjects made a complete recovery.

DNA-binding specificity of the homeodomain-leucine zipper domain

Homeodomain-leucine zipper (HD-Zip) proteins are putative transcription factors identified only in plants. The study of the DNA-binding properties of the ATHB-1 and -2 HD-Zip (HD-Zip-1 and -2) domains showed that they interact with DNA as homodimers and recognize two distinct 9 bp pseudopalindromic sequences, CAAT(A/T)ATTG (BS-1) and CAAT(G/C)ATTG (BS-2), respectively, as determined by selecting high-affinity binding sites from random-sequence DNA. Here, we report a mutational analysis of the HD-Zip-2 domain. We determined that conserved amino acid residues of helix 3, Val47 and Asn51, and Arg55 are essential for the DNA-binding activity of the HD-Zip-2 domain. We demonstrated that the preferential recognition of a G/C base-pair at the central position by the HD-Zip-2 domain is abolished either by the replacement of Arg55 with lysine or by the substitution of Glu46 and Thr56 with the corresponding residues of the HD-Zip-1 domain (alanine and tryptophan, respectively). In contrast, substitution of Arg55 with lysine in the HD-Zip-1 domain significantly reduced DNA-binding activity without changing the specificity of recognition. Finally, we determined that differences in residues outside helix 3 further contribute to the DNA-binding specificity of the HD-Zip domain. Taken together, the data strongly suggest that the preferential recognition of BS-2 and -1 by the HD-Zip-2 and -1 domains, respectively, may be attributable to a distinct orientation of the side-chain of Arg55 in these two domains.

Circulating fragments of myelin-associated alpha 6 beta 4 integrin in Guillain-Barré syndrome

Guillain-Barré-Strohl syndrome (GBS) is an acute peripheral neuropathy causing reversible myelin damage. alpha 6 beta 4 is a laminin receptor of Schwann cells and myelin. Along with myelin breakdown, alpha 6 beta 4 immunoreactivity might be detected in patients' sera and provide a marker for monitoring GBS course. MAbs to beta 4 and alpha 6 were used in an ELISA test to detect protein in GBS serum samples as in normal individuals. In 66% GBS patients, alpha 6 beta 4 immunoreactivity was detected while controls were negative. The level of beta 4 was followed in different patients and found to fluctuate, always being positive in at least one sample. Treatment lowered immunoreactivity in two beta 4-positive GBS sera. Then, circulating alpha 6 beta 4 fragments represent a novel marker of extensive peripheral myelin damage and may be used to validate clinical diagnosis of GBS, evaluate its course and activity.

[Dental enamel hypoplasia in a group of celiac disease patients. Clinico-epidemiologic correlations]

BACKGROUND

The aim of present study was to carry out a personal clinical-epidemiological research concerning a possible correlation between coeliac disease and enamel hypoplasia.

MATERIALS AND METHODS

Forty-five patients of Cam-pania, aged between 2 and 26 years old, with a diagnosis of coeliac disease (diagnosis in accordance with recent protocol ESPGAN), were subjected to a careful dental examination: at the same time a control-group formed by 105 healthy subjects, of the same province, age- and sex-matched with coeliac patients was examined.

RESULTS

The finding of enamel hypoplasias was more significant in coeliac patients (11 cases with a percentage of 2.4%) than in controls (5 cases with a percentage of 4.7%).

CONCLUSIONS

The percent rate, if on the one hand is lower than in Finnic studies, on the other hand fundamentally reflects the results of studies on the same topic carried out by other Italian groups. Furthermore also in this research the involvement of milk-teeth is observed as reported by other authors. This appears to confirm a clear association between coeliac disease and dental hard tissues alterations.

PK12, a plant dual-specificity protein kinase of the LAMMER family, is regulated by the hormone ethylene

The ethylene signal is transduced in plant cells via phosphorylation events. To identify protein kinases whose levels of expression are modulated by the plant hormone ethylene, we utilized a differential reverse transcriptase-polymerase chain reaction approach using mRNA extracted from ethylene-treated and untreated tobacco leaves. An ethylene-induced cDNA clone, PK12, encoding a protein kinase, was isolated. PK12 is a new member of the recently defined LAMMER family of protein kinases, which has been identified in mammals, flies, yeasts, and plants. The LAMMER kinases are related to the cell cycle-dependent CDC2-type kinases and are characterized by their similarity at kinase subdomain X. The recombinant PK12 protein autophosphorylates in vitro on serine, threonine, and tyrosine residues, thereby making it a member of the dual-specificity protein kinases. Immunoprecipitation of PK12 from plant extracts and kinase assay revealed that the apparent PK12 activity is rapidly and transiently increased when plants are treated with ethylene. By using in situ hybridization, we detected accumulation of the PK12 transcript in leaves after ethylene treatment and in the untreated flower abscission zone. The tissue in this zone is known to constitutively express ethylene-regulated genes.