Fine-mapping of a major locus for Fusarium wilt resistance in flax (Linum usitatissimum L.)

KEY MESSAGE

Fine-mapping of a locus on chromosome 1 of flax identified an S-lectin receptor-like kinase (SRLK) as the most likely candidate for a major Fusarium wilt resistance gene. Fusarium wilt, caused by the soil-borne fungal pathogen Fusarium oxysporum f. sp. lini, is a devastating disease in flax. Genetic resistance can counteract this disease and limit its spread. To map major genes for Fusarium wilt resistance, a recombinant inbred line population of more than 700 individuals derived from a cross between resistant cultivar 'Bison' and susceptible cultivar 'Novelty' was phenotyped in Fusarium wilt nurseries at two sites for two and three years, respectively. The population was genotyped with 4487 single nucleotide polymorphism (SNP) markers. Twenty-four QTLs were identified with IciMapping, 18 quantitative trait nucleotides with 3VmrMLM and 108 linkage disequilibrium blocks with RTM-GWAS. All models identified a major QTL on chromosome 1 that explained 20-48% of the genetic variance for Fusarium wilt resistance. The locus was estimated to span ~ 867 Kb but included a ~ 400 Kb unresolved region. Whole-genome sequencing of 'CDC Bethune', 'Bison' and 'Novelty' produced ~ 450 Kb continuous sequences of the locus. Annotation revealed 110 genes, of which six were considered candidate genes. Fine-mapping with 12 SNPs and 15 Kompetitive allele-specific PCR (KASP) markers narrowed down the interval to ~ 69 Kb, which comprised the candidate genes Lus10025882 and Lus10025891. The latter, a G-type S-lectin receptor-like kinase (SRLK) is the most likely resistance gene because it is the only polymorphic one. In addition, Fusarium wilt resistance genes previously isolated in tomato and Arabidopsis belonged to the SRLK class. The robust KASP markers can be used in marker-assisted breeding to select for this major Fusarium wilt resistance locus.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

[Venezuelan consensus guidelines on the use of magnetic resonance in diagnosis and follow up of patients with multiple sclerosis]

INTRODUCTION

The clinical use of magnetic resonance (MR) in patients with multiple sclerosis (MS) has advanced markedly over the past few years. Several groups around the world have developed consensus guidelines about the role of MR in MS at diagnosis and during follow up. However, in some regions is difficult to extrapolate the recommendations.

AIM

To provide recommendations for the implementation of MR in MS patients at diagnosis and follow up in Venezuela.

DEVELOPMENT

A group of experts from Venezuela that included neurologists and radiologists, by using the online surveys methodology as well as face to face meetings developed the intended consensus for the use of MR during the diagnosis and follow up of MS patients in Venezuela. Seventeen recommendations were established based on published evidence and the expert opinion. Recommendations focused on the role of conventional MR techniques and brain atrophy measurement in MS patients both at diagnosis and during follow-up.

CONCLUSIONS

The recommendations of this consensus guidelines attempts to optimize the health care and management of patients with MS in Venezuela.

Apoptotic markers in cultured fibroblasts correlate with brain metabolites and regional brain volume in antipsychotic-naive first-episode schizophrenia and healthy controls

Cultured fibroblasts from first-episode schizophrenia patients (FES) have shown increased susceptibility to apoptosis, which may be related to glutamate dysfunction and progressive neuroanatomical changes. Here we determine whether apoptotic markers obtained from cultured fibroblasts in FES and controls correlate with changes in brain glutamate and N-acetylaspartate (NAA) and regional brain volumes. Eleven antipsychotic-naive FES and seven age- and gender-matched controls underwent 3-Tesla magnetic resonance imaging scanning. Glutamate plus glutamine (Glx) and NAA levels were measured in the anterior cingulate (AC) and the left thalamus (LT). Hallmarks of apoptotic susceptibility (caspase-3-baseline activity, phosphatidylserine externalization and chromatin condensation) were measured in fibroblast cultures obtained from skin biopsies after inducing apoptosis with staurosporine (STS) at doses of 0.25 and 0.5 μM. Apoptotic biomarkers were correlated to brain metabolites and regional brain volume. FES and controls showed a negative correlation in the AC between Glx levels and percentages of cells with condensed chromatin (CC) after both apoptosis inductions (STS 0.5 μM: r = -0.90; P = 0.001; STS 0.25 μM: r = -0.73; P = 0.003), and between NAA and cells with CC (STS 0.5 μM induction r = -0.76; P = 0.002; STS 0.25 μM r = -0.62; P = 0.01). In addition, we found a negative correlation between percentages of cells with CC and regional brain volume in the right supratemporal cortex and post-central region (STS 0.25 and 0.5 μM; P < 0.05 family-wise error corrected (FWEc)). We reveal for the first time that peripheral markers of apoptotic susceptibility may correlate with brain metabolites, Glx and NAA, and regional brain volume in FES and controls, which is consistent with the neuroprogressive theories around the onset of the schizophrenia illness.

New treatment for faecal incontinence using zinc-aluminium ointment: a double-blind randomized trial

AIM

In a randomized double-blind study the therapeutic effect of a novel zinc-aluminium ointment was compared with placebo in patients with faecal incontinence.

METHOD

A randomized double-blind trial was performed. Patients who met the inclusion criteria were randomized to receive the ointment or a placebo. All were evaluated prior to and 3 weeks after ointment application, using the Wexner incontinence score and the Fecal Incontinence Quality of Life (FIQL) score.

RESULTS

Fifty patients were randomized and six were lost to follow-up, leaving 24 in the treatment and 20 in the placebo group. The average ages were 61.3 and 60.7 years. The respective Wexner scores prior to intervention were 16.6 and 16.7. They decreased significantly after treatment to 8.5 and 13.1 (P<0.001 and P=0.002 respectively). There was a significant difference in the final scores, favouring the treatment group (P=0.001). The FIQL scores for the treatment group were also significantly better in all parameters compared with those of the placebo group.

CONCLUSION

The study shows that the zinc-aluminium based ointment decreases faecal incontinence significantly compared with placebo.

Deletions and duplications of the 15q11-q13 region in spermatozoa from Prader-Willi syndrome fathers

Prader-Willi syndrome (PWS) is a genomic disorder mostly caused by deletions of 15q11-q13 region (70%). It has been suggested that the particular genomic architecture of 15q11-q13 region, characterized to be flanked by low copy repeats, could predispose it to Non-Allelic Homologous Recombination (NAHR). However, no studies in gametes of fathers of PWS individuals have been published to date. The objective of the study was to assess the incidence of 15q11-q13 deletions and duplications in spermatozoa from PWS fathers and to appraise the value of the data obtained for the estimation of the risk of recurrence for the syndrome. Semen samples from 16 fathers of PWS individuals and 10 control donors, were processed by triple-color fluorescence in situ hybridization. A customized combination of probes was used to discriminate between normal, deleted and duplicated sperm genotypes. A minimum of 10,000 sperm were scored for every single sample. A significant increase in the frequency of 15q11-q13 deletions and duplications were observed in PWS fathers (0.90 +/- 0.14%) compared with control donors (0.47 +/- 0.07%). Ten out of 16 individuals contributed to this population increase (P < 0.01), suggesting a predisposition for 15q11-q13 reorganizations. Statistical differences were observed in the frequency of 15q11-q13 deletions and duplications in fathers of PWS individuals (0.59 versus 0.31%; P = 0.001), indicating that intra-chromatid NAHR exchanges also substantially contribute to the rearrangements. Results demonstrated the increased susceptibility of some fathers of PWS individuals to generate 15q11-q13 deletions, suggesting that the screening of anomalies in sperm should be advisable as a valuable complement for genetic counseling.

[Epidemiologic studies of cerebellopontine angle tumors surgically treated in Maracaibo, Venezuela, in 1985-1999]

OBJECTIVE

To analyze the epidemiological, clinical and neuropathological data of cases of cerebellopontine angle (CPA) tumors.

MATERIAL AND METHODS

The clinical records, neuroimaging and neuropathological studies of 50 patients with diagnosis of CPA tumor operated in different hospitals of Maracaibo, Venezuela, during the lapse January 1st, 1985-December 31, 1999 were reviewed. The variables age, gender, side of the lesion and neuropathological diagnosis were analyzed.

RESULTS

A 2:1 female to male ratio was observed. Median age was 48 +/- 12.7 years. Acoustic neuromas (AN) represented 48% of the cases, whereas nonacoustic neuroma tumors (NANT) made up for the rest (52%). Meningiomas were the second more commonly diagnosed lesions, they constituted 32% of the cases. Meningiomas and AN were more frequent in women, their ratios being 7:1 and 1.6:1, respectively. In 60% of the cases the signs and symptoms became eloquent in patients of the fourth and fifth decades of life.

CONCLUSIONS

The difference between our results and the ones previously reported in the medical literature are due in part to the predominance of female patients in our series. Endocrinologic, genetic and biochemical factors could also be responsible; nevertheless, this does not constitute the objective of the present study.

[Causes of dementia in Maracaibo, Venezuela: a re-evaluation]

INTRODUCTION AND OBJECTIVES

In a previous report we analyzed the causes of dementia in an autopsy population from four hospitals of Maracaibo, Venezuela. Our results showed that vascular dementia (VD) accounted for 86.7% of all clinically diagnosed demented patients, whereas no cases of Alzheimer's disease (AD) were neuropathologically demonstrated. Six years later, we undertook a similar study, in order to re-evaluate the frequency of the different causes of dementia in our country.

MATERIAL AND METHODS

We studied 611 adult brains obtained from autopsies performed during the period 1992-1998; 39 of these came from clinically demented patients.

RESULTS

Vascular dementia was disclosed in 33 cases (84.6%), five cases (12.82%) showed evidence of specific causes for dementia other than VD or AD, and in one of the cases (2.56%) the neuropathological changes were specific for AD.

CONCLUSIONS

Our current results confirm the conclusions of our previous study and contrast with the vast majority of reports in the medical literature regarding the frequency of the different causes of dementia, except for studies from China, Japan and Russia that yielded similar findings as ours. At present, further investigations are being undertaken in order to come up with possible explanations for these differences.

Hallervorden-Spatz disease: two new early childhood onset cases

Hallervorden-Spatz disease is a rare, autosomal-recessive hereditary condition characterized by early onset of progressive movement alterations such as dystonia, rigidity, and choreoathetosis, which is usually associated with pyramidal signs and mental deterioration. The authors report two cases for which diagnosis of Hallervorden-Spatz disease was based on clinical manifestations that appeared during the first year of life, illness progression, and late-stage magnetic resonance imaging findings. The possibility that these two cases, along with other previously described rare instances with similar clinical features, be considered as a variant of subtype of the early-onset type of Hallervorden-Spatz disease is suggested. The need to differentiate these cases from cases of static encephalopathy with mental retardation and motor impairment is also stressed.

Solitary fibrous tumor of the meninges

Intracranial fibrous tumors are unusual growths that occur almost exclusively in young individuals. Most of these lesions are intra-axial, however, on extremely rare occasions they arise from the leptomeninges and compress the adjacent brain. The authors report the case of a benign solitary fibrous tumor of the meninges in a 14-year-old girl who presented with a 5-month history of generalized headaches. NMR imaging displayed a left parietal mass, which mimicked a meningioma.

[Application of RUG-T18 classification system to elderly patients admitted to a university hospital]

BACKGROUND

Among case mix classifications, the best for hospitalized elders is the Resource Utilization Groups (RUG) system, which allows a better location of patients, resource administration and the design of health care strategies for elderly people.

AIM

To report the results of RUG-T18 classification of elderly patients admitted to an university hospital.

PATIENTS AND METHODS

RUG-T18 classification was applied to 210 patients aged 75.2 +/- 7.2 years old, 108 male, admitted to the Clinical Hospital of the Catholic University of Chile.

RESULTS

The clinical classification of assessed patients was rehabilitation in 50.9% of cases, special care in 10.5%, clinically complex in 37.1% and reduced physical functions in 0.5%. None had behavioral alterations. There were no differences between subjects older or younger than 75 years old. Daily life activities showed that help was required for sphincter control in 46% of patients, for feeding in 44% and for mobilization in 64% (28% of patients required help from two or more people). Geriatric assessment showed that, since 1993, the proportion of elders with greater functional derangement increased from 18 to 28%, and the proportion of those with mental disturbances from 4 to 12%, specially among those over 75 years old.

CONCLUSIONS

Most elders admitted to the hospital are classified in the superior categories of the RUG-T18 system and have severe mental and functional limitations. These patients require a multidisciplinary approach with a great emphasis in rehabilitation.

[Central nervous system infection by free-living amebas: report of 3 Venezuelan cases]

INTRODUCTION

Infection of the Central Nervous System by free living amebas is an unusual event, 344 cases have been reported to date. The disease becomes evident in two different clinical fashions: Primary Amebic Meningoencephalitis (PAM) caused by Naegleria fowleri and Granulomatous Amebic Encephalitis (GAE) induced by Spp. of Acanthamoeba and Balamuthia.

CLINICAL CASES

The authors report three new cases from Venezuela. Case 1. 34 years old man, with a chief complaint of general malaise, headache and fever, a diagnosis of common cold was made and the patient was treated as such, he did not improve and was admitted to the hospital with deterioration of his clinical status; the patient died 10 days after the onset of his illness which was determined to be GAE produced by Balamuthia mandrillaris. Case 2. 8 years old female admitted to the hospital because of fever, headache and generalized seizures of sudden onset; neurocysticercosis was diagnosed and following improvement the patient was discharged and readmitted on two occasions because of relapse and worsening of her illness, she died 2 months after the onset of her disease that was diagnosed by autopsy as GAE due to Balamuthia mandrillaris. Case 3. 16 years old male, previously healthy, who following immersion in a water tank was admitted to the hospital because of meningeal irritation that progressed to coma and death in a 7 day lapse; autopsy revealed PAM by Naegleria fowleri. The two cases of GAE due to Balamuthia mandrillaris occurred in apparently immunocompetent individuals, contrary to the statement that these microorganisms are opportunistic.

CONCLUSION

We believe that neurological infection by amphizoic amebas is being underdiagnosed, probably due to ignorance regarding this pathology or because of a very low autopsy rate in most countries.

[Geriatric evaluation of elderly patients at a university hospital]

The aim of this work was to evaluate general aspects, medical diagnoses, degree of disability, mental status and social support of hospitalized elders using a Geriatric Assessment Scale, devised at the Catholic University. Ninety eight hospitalized subjects (58 female, aged 60 to 74 years old) were surveyed before discharge. Results showed that 34% had serious handicaps in their daily living and required third party help, 14% had a moderate cognitive impairment and that 12% lacked social or family support. We conclude that the scale is useful, easy to use and allows to obtain a thorough diagnosis of hospitalized elders.

Isolation of a fibrinolytic protease, M4, from venom of Crotalus molossus molossus (northern blacktail rattlesnake)

M4, a fibrinolytic protease, was isolated from the venom of Crotalus molossus molossus. It has a pI of 9.6 and a molecular weight of 27,000. The protease hydrolyzes the A alpha and B beta chains of fibrinogen, and the alpha and beta chains of fibrin. This activity was inhibited by EDTA and restored by Ca2+ or Zn2+, but not Mg2+. The protease hydrolyzed hide power azure and casein, but it had no effect on collagen, hyaluronic acid, complement or synthetic substrates for thrombin, plasmin or kallikrein. Subcutaneous injections into mice with doses as high as 100 micrograms did not cause hemorrhage. This protease may have therapeutic use as a thrombolytic agent.

Isolation of two hemorrhagic toxins from Crotalus basiliscus basiliscus (Mexican west coast rattlesnake) venom and their effect on blood clotting and complement

1. Two hemorrhagic toxins of mol. wt 27,000 (B1) and 27,500 (B2) and pI 9.8 and 5.2 respectively were isolated from Crotalus basiliscus venom. 2. The two proteinases did not cross-react antigenically. 3. Both toxins caused hemorrhage in mice and each was capable of hydrolyzing hide power azure, casein, collagen and fibrin. 4. B1 hydrolyzed the A alpha, B beta and gamma chains of fibrinogen. B2 hydrolyzed the A alpha and B beta chains of fibrinogen, but not the gamma chain. 5. Both proteinases inactivated guinea pig complement.