Distribution of Pseudocercospora species causing Sigatoka leaf diseases of banana in Uganda and Tanzania

Sigatoka leaf diseases are a major constraint to banana production. A survey was conducted in Tanzania and Uganda to assess the distribution of Pseudocercospora species and severity of Sigatoka leaf diseases. Pseudocercospora species were identified using species-specific primers. Sigatoka-like leaf diseases were observed in all farms and on all cultivars, but disease severity varied significantly (P < 0.001) between countries, districts/regions within countries, altitudinal ranges and banana cultivars. In all regions except Kilimanjaro, P. fijiensis, the causal agent of black Sigatoka, was the only pathogen associated with Sigatoka disease. Mycosphaerella musae was associated with Sigatoka-like symptoms in Kilimanjaro region. Black Sigatoka disease was more severe in Uganda, with a mean disease severity index (DSI) of 37.5%, than in Tanzania (DSI = 19.9%). In Uganda, black Sigatoka disease was equally severe in Luwero district (mean DSI = 40.4%) and Mbarara district (mean DSI = 37.9%). In Tanzania, black Sigatoka was most severe in Kagera region (mean DSI = 29.2%) and least in Mbeya region (mean DSI = 11.5%). Pseudocercospora fijiensis, the most devastating sigatoka pathogen, was detected at altitudes of up to 1877 m a.s.l. This range expansion of P. fijiensis, previously confined to altitudes lower than 1350 m a.s.l. in East Africa, is of concern, especially for smallholder banana farmers growing the susceptible East African Highland bananas (EAHB). Among the banana varieties sampled, the EAHB, FHIA hybrids and Mchare were the most susceptible. Here, the loss of resistance in Yangambi KM5, a banana variety previously resistant to P. fijiensis, is reported for the first time.

Understanding groundwater salinization mechanisms to secure freshwater resources in the water-scarce city of Maputo, Mozambique

In this study hydrochemical, isotopic and multivariate statistical tools are combined with a recharge analysis and existing geophysical data to improve understanding of major factors controlling freshwater occurrence and the origins of high salinities in the multi-layered coastal aquifer system of the Great Maputo area in Mozambique. Access to freshwater in this semi-arid area is limited by an inefficient public supply network, scarce surface waters, long droughts and an increasing population growth. Groundwater has a large potential to enhance water security, but its exploitation is threatened by both coastal and inland salinization mechanisms that are poorly understood. A GIS approach is utilized to classify potential recharge zones based on hydrogeological properties and land use/cover, whereas potential recharge rates are estimated through a root zone water balance method. In combination with water stable isotope data results reveal that extreme rainfall events provide the most relevant contributions to recharge, and interception and evaporation play an important role in the low recharge areas. Hierarchical clustering of hydrochemical and isotopic data allows the classification of six water groups, varying from fresh to brackish/salt waters. Corresponding scatter plots and PHREEQC modelling show evaporation and mixing with seawater (up to 5%) as major processes affecting salinity in the area. The co-occurrence of high alkalinity and Cl concentrations, in combination with piezometric and geo-electrical data, suggests that: 1) inland brackish/salt groundwater is caused by mixing with seawater trapped within clay layers; and 2) brackish/salt surface waters result from seepage of brackish groundwater into rivers and wetlands, followed by evaporation, hence increasing salinity and δ¹⁸O values. Mixing with small fractions of trapped seawater as main salinity source, rather than halite dissolution, is further corroborated by Br/Cl ratios of brackish/salt water samples near the ocean ratio. Cation exchange upon salinization is mainly observed in the semi-confined aquifer, while freshening takes place in the phreatic aquifer, particularly in areas presenting high recharge rates.

Complications of endovenous lasers

Endovenous laser ablation (EVLA) and radiofrequencey ablation have become the procedures of choice for the treatment of superficial venous insufficiency. Their minimally invasive technique and safety profile when compared with operative saphenectomy have led to this change. As EVLA has replaced saphenectomy as the procedure of choice, the distribution of complications has changed. We evaluated the most common and most devastating complications in the literature including burns, nerve injury, arterio-venous fistula (AVF), endothermal heat-induced thrombosis and deep venous thrombosis. The following review will discuss the most frequently encountered complications of treatment of superficial venous insufficiency using EVLA. The majority of the complications described can be avoided with the use of good surgical technique and appropriate duplex ultrasound guidance. Overall, EVLA has an excellent safety profile and should be considered among the first line for treatment of superficial venous reflux.

Experience and technique for the endovascular management of iatrogenic subclavian artery injury

BACKGROUND

Inadvertent subclavian artery catheterization during attempted central venous access is a well-known complication. Historically, these patients are managed with an open operative approach and repair under direct vision via an infraclavicular and/or supraclavicular incision. We describe our experience and technique for endovascular management of these injuries.

METHODS

Twenty patients were identified with inadvertent iatrogenic subclavian artery cannulation. All cases were managed via an endovascular technique under local anesthesia. After correcting any coagulopathy, a 4-French glide catheter was percutaneously inserted into the ipsilateral brachial artery and placed in the proximal subclavian artery. Following an arteriogram and localization of the subclavian arterial insertion site, the subclavian catheter was removed and bimanual compression was performed on both sides of the clavicle around the puncture site for 20 min. A second angiogram was performed, and if there was any extravasation, pressure was held for an additional 20 min. If hemostasis was still not obtained, a stent graft was placed via the brachial access site to repair the arterial defect and control the bleeding.

RESULTS

Two of the 20 patients required a stent graft for continued bleeding after compression. Both patients were well excluded after endovascular graft placement. Hemostasis was successfully obtained with bimanual compression over the puncture site in the remaining 18 patients. There were no resultant complications at either the subclavian or the brachial puncture site.

CONCLUSION

This minimally invasive endovascular approach to iatrogenic subclavian artery injury is a safe alternative to blind removal with manual compression or direct open repair.

O6-Methylguanine-DNA-methyltransferase in recurring anaplastic ependymomas: PCR and immunohistochemistry

Ependymomas are the third most common brain tumor in children. The post surgical management is controversial. There are no convincing data on an effective role for chemotherapy. O(6)-Methylguanine-DNA-Methyltransferase (MGMT) is a DNA repair protein considered to be a chemosensitivity predictor. Hypermethylation of the MGMT gene promoter is an important cause of MGMT inactivation. We evaluated the MGMT gene promoter methylation and the immunohistochemical MGMT protein expression in 12 recurrent anaplastic ependymomas affecting children. Our purpose was to investigate the molecular rationale of the administration of alkylating agents to children affected by recurrent anaplastic ependymomas. All ependymomas lacked MGMT promoter hypermethylation and 9 (75%) showed high MGMT protein expression (>50% tumoral cells). Differences between different recurrences in the same patient were not observed. These results may indicate MGMT as a factor of chemoresistance to alkylating drugs in anaplastic ependymomas and support the uncertainties regarding the actual benefit of chemotherapy for patients with anaplastic ependymomas.

Diffuse and focal brain stem tumors in childhood: prognostic factors and surgical outcome. Experience in a single institution

OBJECTIVE

Brainstem tumors (BSTs) are usually gliomas and are divided into diffuse BSTs (DBSTs) and focal BSTs (FBSTs). The aim of this study is to investigate the different outcomes of these two entities.

METHODS

Thirty-one patients with BSTs were admitted to our institution from 1995 to 2003. Patients with DBSTs were treated with locoregional radiotherapy (1.8 Gy/day for 54 Gy) and weekly vincristine for radiosensitization (1.5 mg/sm for six total doses). Patients with FBSTs underwent surgical resection. Chemotherapy and/or radiotherapy were considered in progression.

RESULTS AND CONCLUSIONS

Fourteen patients were diagnosed as having DBSTs. The responses to treatment were ten cases of partial response, three of stable disease, and one of progressive disease. General and/or neurological symptoms improved in more than 80% of patients. The median time from diagnosis to progression and to death were, nonetheless, 8 (range of 3-13) and 13 (range of 4-25) months, respectively, with a 2-year overall survival rate of 12.3% [standard error (SE) 11.2]. Seventeen patients were diagnosed as having FBSTs. Gross total removal was achieved in 4/17 cases, subtotal removal in 7/17, and partial removal in 6/17. There was one surgery-related death. Eight out of 17 patients had adjuvant chemo- and/or radiotherapy after progression: 6/8 are without neurological symptoms and 2/8 have died due to tumor progression. The 4-year overall and disease-free survival rates are 87.4 (SE 8.4) and 58.8% (SE 11.9), respectively, the extent of resection being the most important prognostic factor (p=0.012). DBSTs continue to carry a dismal prognosis, thus demanding new treatment modalities; FBSTs can be treated surgically and patients benefit from a better prognosis.

Influence of thyroid in nervous system growth

Nervous system growth and differentiation are closely correlated with the presence of iodine and thyroid hormones in initial development stages. In the human species, encephalon maturation during the first quarter of pregnancy is affected according to recent studies by the transplacenta passage of maternal thyroid hormones while it depends on initial iodiothyronin secretion by the foetal gland after the 12th week of pregnancy. Thyroid hormone deficiency during nervous system development causes altered noble nervous cells, such as the pyramidal cortical and Purkinje cells, during glial cell proliferation and differentiation alike. Neurons present cell hypoplasia with reduced axon count, dendritic branching, synaptic spikes and interneuron connections. Oligodendrocytes decrease in number and average myelin content consequently drops. Biochemical studies on hypothyroid rats have demonstrated alterations to neuron intraplasmatic microtubule content and organisation, changed mitochondria number and arrangement and anomalies in T3 nuclear and citoplasmatic receptor maturation. Alterations to microtubules are probably responsible for involvement of the axon-dendrite system, and are the consequence of deficient thyroid hormone action on the mitochondria, the mitochondria enzymes and proteins associated with microtubules. Nuclear and citoplasmatic receptors have been identified and gene clonation studies have shown two families of nuclear receptors that include several sub-groups in their turn. A complex scheme of temporal and spatial expression of these receptors exists, so they probably contribute with one complementary function, although their physiological role differs. The action of thyroid hormones occurs by changing cell protein levels because of their regulation at the transcriptional or post-transcriptional level. Genes submitted to thyroid hormone control are either expressed by oligodendrytes, which are myelin protein coders or glial differentiation mediators, or are nervous cell specific, genes coding neurotropins or proteins involved in synaptic excitation. The use of new PMRS and MRI non-invasive techniques has enabled identification of metabolic and biochemical markers for alterations in the encephalon of untreated hypothyroid children. Even an excess of thyroid hormones during early nervous system development can cause permanent effects. Hyperthyroidism in fact initially induces accelerated maturation process including cell migration and differentiation, extension of dendritic processes and synaptogenesis but a later excess of thyroid hormones causes reduction of the total number of dendritic spikes, due to early interruption of neuron proliferation. Experimental studies and clinical research have clarified not only the correlation between nervous system maturation and thyroid function during early development stages and the certain finding from this research is that both excess and deficient thyroid hormones can cause permanent anatomo-functional alterations to the nervous system.

Chiari type I anomalies in children and adolescents: minimally invasive management in a series of 53 cases

The authors studied the role of the sole posterior fossa bony decompression in the management of symptomatic children affected by Chiari type I anomalies. The series in the pediatric literature of this subject were reviewed and compared with that presented in this article. From May 1994 to December 1998, 53 patients (3 months to 26 years) were observed. They were divided into: asymptomatic patients (27), who received no surgical treatment and were only subject to clinical observation; symptomatic patients (brain stem compression 16, syringomyelia 10, including 7 with holocord). All the symptomatic patients were treated with the same surgical approach: bony decompression of posterior fossa with removal of the posterior arch of C-1 and the outer layer of the dura without dural opening. In all 16 (100%) of the 16 patients with brain stem compression the symptoms resolved or improved; in patients with syringomyelia the symptoms were resolved or improved in 94.4% of cases. Two children required further surgery after 13 and 24 months, respectively. This series seems to demonstrate that even a simple extradural surgical approach, with a lower rate of postoperative complications and short stay in hospital, is sufficient to arrest the disease and to improve the symptomatology in a high percentage of cases (97.2%), which is comparable to that achieved with other, more aggressive, procedures.

Factors at onset predictive of lasting remission in pediatric patients with Graves' disease followed for at least three years

Seventeen pediatric patients (mean age at diagnosis 10 yr and 9 mo +/- 2 yr and 9 mo) with Graves' disease treated with 0.3-0.7 mg/kg/day methimazole and followed for at least three years, during which drug suspension was attempted on attainment of good clinical and metabolic compensation, were retrospectively studied to look for factors predictive of lasting remission present at onset. Lasting remission was defined as a clinical and laboratory picture of euthyroidism lasting at least one year in the absence of treatment at the end of the follow-up. A distinction was drawn between patients who reached remission after one or two courses (groups 1 and 2) and those who never attained a lasting remission (group 3). TRAb (TBIAb) levels at onset were the only factor significantly correlated with the response to treatment. Age at diagnosis, goiter size and fT3 and fT4 concentrations were not significantly correlated with the clinical picture. The series was too small to allow any assessment of the real importance of these factors, though a generally better response was displayed by children over 11 years old, without appreciable or with very small goiter and moderately increased thyroid hormone levels at onset (fT3 < 25 pg/ml in 10/10 in groups 1 and 2 and 2/7 in group 3 patients; fT4 < 40 pg/ml in 7/10 in groups 1 and 2 and 3/7 in group 3 patients). It was also found that better results were obtained when the initial drug course was protracted for at least two years.

Growth hormone, insulin-like growth factor-I and somatostatin in human fetus, newborn, mother plasma and amniotic fluid

During pregnancy, organism development and its differentiation are stimulated and modulated by fetal and placental hormones. However the exact role played by all the different growth factors has not been explained yet. This study summarizes knowledge about secretion, regulation and role of GH, IGF-1 and SRIF during perinatal age. It also reports the results of researches into GH, IGF-1 and SRIF in amniotic fluid, in mothers and in newborns at delivery and at four days of age. Amniotic fluid GH levels proved significantly higher during middle pregnancy that at delivery (p < 0.001); a significant difference was also found between mean GH concentrations observed in amniotic fluid collected at delivery in preterm and full-term pregnancies. In amniotic fluid, significant reductions of SRIF and IGF-1 concentrations correspond to a sudden decrease of GH concentration during the last months of pregnancy. Fetal serum GH levels resulted higher than venous cordonal GH concentration at birth (p < 0.001). High levels of IGF-1 were found in the amniotic fluid and in the maternal plasma. These values were higher than those observed in cord blood during pregnancy or at delivery. Preterm and full-term newborns showed similar serum GH levels at birth and at the age of 4 days. Mean GH values in newborns, both at birth and at the age of 4 days, proved to be significantly higher than the values of their mothers (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[Neonatal hepatic cholestasis with particular regard for the use of radioisotopes in its diagnosis]

The aim of this study was to assess the diagnostic sensitivity and specificity of hepatobiliary scintigraphy using a 99mTc-HIDA compound to differentiate intrahepatic cholestasis from extrahepatic forms during the first months of life. The tracer used was acid N-(2,6)-diethylacetanylido-iminodiacetic (diethyl-HIDA) with almost exclusively biliary excretion and a high concentration of radioactivity in the bile. Each neonate was injected with 0.5 mg/kg i.v. of the compound marked with a dose of 99mTc equivalent to 80-100 microCi/kg. Scintigraphic recordings were carried out every 10' for the first hour and further controls were performed at 2, 3, 4, 8 and 24 hours. Scintiphotos were obtained using a Polaroid scintillation camera, PHO Gamma V. Fifty-four patients were included in the study (34 males and 20 females) aged between 4 days and 3 months old. All patients were clinically suspected of pathologies involving the hepatobiliary tract. All cases were affected by persistent jaundice (total bilirubin between 1.8 and 39.6 mg%) with predominantly direct bilirubin (range 1.5-26.2 mg%), acholic feces and hyperchromic urine. Hepato-biliary scintigraphy revealed an intestinal excretion of tracer in 31 out of the 54 neonates examined, excluding the presence of an extrahepatic obstruction of the biliary tract. On the other hand, only 13 out of 23 cases in which no enteric excretion of the tracer was observed, was the final diagnosis one extrahepatic cholestasis. Scintigraphic tests therefore showed a 100% sensitivity associated with a specificity of only 56.52%. This demonstrates that the finding of tracer in the intestine is pathognomonic of the permeability of extrahepatic biliary ducts and that biliary atresia can be ruled out. On the contrary, the absence of the intestinal excretion of the tracer is nor constantly associated with biliary atresia. This study has confirmed this finding in 10 cases of intrahepatic cholestasis (4 hypoplasias of the intrahepatic biliary tract, 3 thick bile syndromes, 3 cases of hepatitis due to cytomegalovirus). In conclusion, the Authors state that hepato-biliary scintigraphy represents a straightforward and non-invasive diagnostic method which enables the permeability of the biliary tract to be assessed in subjects with jaundice.

[Thyroid hormones and the development of the nervous system]

The growth and differentiation of the central nervous system are closely related to the presence of iodine and thyroid hormones. During the first trimester of human pregnancy the development of the nervous system depends entirely on the availability of iodine; after 12 week of pregnancy it depends on the initial secretion of iodothyronine by the fetal thyroid gland. During the early stages of the development of the nervous system a thyroid hormone deficit may provoke alterations in the maturation of both noble nervous cells (cortical pyramidal cells, Purkinje cells) and glial cells. Hypothyroidism may lead to cellular hypoplasia and reduced dendritic ramification, gemmules and interneuronal connections. Experimental studies in hypothyroid rats have also shown alterations in the content and organization of neuronal intracytoplasmatic microtubules, the biochemical maturation of synaptosomes and the maturation of nuclear and cytoplasmatic T3 receptors. Excess thyroid hormones during the early stages of development may also cause permanent damage to the central nervous system. Hyperthyroidism may initially induce an acceleration of the maturation processes, including the migration and differentiation of cells, the extension of the dendritic processes and synaptogenesis. An excess of thyroid hormones therefore causes neuronal proliferation to end precociously leading to a reduction of the total number of gemmules. Experimental research and clinical studies have partially clarified the correlation between the maturation of the nervous system and thyroid function during the early stages of development; both a deficit and excess of thyroid hormones may lead to permanent anatomo-functional damage to the central nervous system.(ABSTRACT TRUNCATED AT 250 WORDS)

[Defects of thyroid hormone synthesis: nosographic study and proposal for a protocol for differential diagnosis]

In addition to the forms of congenital hypothyroidism caused by dysgenesis of the thyroid gland (agenesia, ectopy), this phenomenon may be caused by enzyme deficiencies of the thyroid hormone synthetic process. These defects, which are hereditary and transmitted as recessive autosomic characters, are clinically manifest in homozygotic subjects in the form of goitres which appears during the neonatal age or, as in more common, during later infancy. At present, mass neonatal screening allows this phenomenon to be diagnosed during the first days of life. The diagnosis of hypothyroidism caused by enzyme deficiency is made on the basis of radioisotopic and ultrasonic studies, and by the assay of plasma levels of thyroglobulin. The exact definition of the specific enzyme activity which is lacking in each case is more complex and has still to be resolved. This study describes the biochemical and pathogenetic characteristics of the different thyroid hormone synthesis defects and includes the findings of previously published diagnosis tests in order to identify the missing enzymatic activity. Lastly, a protocol for the differential diagnosis of the various types of defect is outlined. A specific etiological definition of the altered thyroid metabolism, while providing further insight into the physiopathology of the thyroid and the epidemiology of enzymatic hormone synthesis defects, should not be a motive for delaying the start of substitutive therapy at the earliest possible stage.

[Kawasaki disease in a subject with G6PD deficiency]

A case of Kawasaki disease in an 8 year old boy affected by G6PD deficiency is described. The patient couldn't be treated with aminosalicylic acid but he received 400 mg/Kg/die of gammaglobulin from 13th to 18th day. No coronary complications occurred, even if coagulopathy was documented, and platelets activation was back to normal three months after the beginning of the disease.

Thyroid and growth: thyroid hormones and development of the nervous system

Growth and differentiation of nervous system are closely influenced by the presence of iodine and thyroid hormones during the first stages of development. The deficiency of thyroid hormones causes alterations of the maturation of the upper nervous cells (pyramidal cortical, Purkinje's cells) and of the glial cells with cell hypoplasia and reduction of dendritic branching, of synaptic spines and interneuronal connections. Experimental studies in hypothyroid rats evidenced impairments in the content and organization of intra-cytoplasmic microtubulin, in the biochemical maturation in synaptosomes and in the maturation of the nuclear and cytoplasmic receptors for T3.