AB0596 PREDICTORS, LONG TERM CLINICAL AND TREATMENT OUTCOMES IN SOUTH ASIAN PATIENTS WITH IDIOPATHIC INFLAMMATORY MYOSITIS: A SINGLE CENTER STUDY

Background:

Idiopathic inflammatory myositis (IIM) are a heterogeneous group of immune-mediated disorders with varied presentations and multiple organ involvement. Data on long term outcome among South Asian patients with IIM is sparse.

Objectives:

To study the long term clinical outcome, treatment responses and factors predicting outcome among adult patients with IIM

Methods:

Patients diagnosed as ‘Idiopathic Inflammatory Myositis’ under the department of Clinical Immunology and Rheumatology at CMC, Vellore, India were screened retrospectively. Patients aged 18 years and above, satisfying Bohan and Peter criteria, having follow up of one year or more with atleast two outpatient or inpatient visits between January 2010 and April 2019 were included in this study. Those patients with connective tissue disease associated myositis were not included. Details on muscle weakness, extramuscular involvement, muscle enzymes and treatment administered were recorded at baseline, 3, 6, 12, 18, 24 months and yearly thereafter. After assessing their cumulative response, categorization of patients into complete and partial responders was done. Complete responders were defined as patients with persistent muscle power of more than 4/5 and/or MMT 8 more than 76/80, complete resolution of skin, articular and lung involvement (if any) as well as muscle enzymes less than twice the upper limit of normal without any documented flares during the entire follow up period. Patients not satisfying the said criterias were grouped as Partial responders. Disease free survival duration was also analyzed.

Results:

Out of 310 patients of IIM identified, 187 (60.3%) patients satisfied the inclusion criteria. Women were 2.2 times more than men and mean age at symptom onset was 35.7±12.6 years. Dermatomyositis was the predominant myositis subtype seen. All patients were put on steroids with the mean dose being 45.9 ± 18.6 mg/day. At baseline, the key immunosuppressants used were methotrexate in 44.9% and mycophenolate in 37.6% patients. The median follow up duration was 48 (25-80) months. An associated malignancy was diagnosed in 3.2% after a median duration of 24.5 months. Five patients expired after a median duration of 80 months from diagnosis. Normal muscle power was attained in 76.1% patients and 88.6% were vocational by the last follow up visit. Steroids were discontinued in 56.7% patients after a median duration of 24 months (p=0.0002). Discontinuation of the immunosuppressant was feasible in 10.2% patients after a median duration of 44 months. Assessment of the cumulative responses revealed a relapsing and remitting course in 45.9%. Outcome predictors in univariate analysis were Jo-1 status, presence of arthritis, interstitial lung disease and pericardial effusion at baseline. On multivariate analysis, absence of pericardial effusion (p=0.011) and interstitial lung disease (p=0.067) at baseline were found to be predictors of complete response. Disease free survival probability estimated at 5 years and 10 years was 91.6% and 72.4% respectively. Estimating the probability gender wise, males achieved disease free status earlier than females.

Conclusion:

A favorable clinical and functional outcome was seen in a significant proportion of these patients with IIM on long term follow up. Pericardial effusion and ILD were identified as predictors of poor clinical outcome.

References:

[1]Taborda AL, Azevedo P, Isenberg DA. Retrospective analysis of the outcome of patients with idiopathic inflammatory myopathy: a long-term follow-up study. Clin Exp Rheumatol. 2014 Apr; 32(2):188–93.

Acknowledgments:

Nil

Disclosure of Interests:

None declared

Head to head comparison of adverse effects and efficacy between high dose deflazacort and high dose prednisolone in systemic lupus erythematosus: a prospective cohort study

BACKGROUND

Deflazacort (DFZ), an oxazoline derivative of prednisolone (PDN), has a dose equivalence of 1.2:1 (mg) to PDN. No study to date has compared adverse effects and efficacy of high doses of DFZ as against high-dose PDN in systemic lupus erythematosus (SLE).

OBJECTIVES

To compare adverse effects of high dose DFZ and PDN in SLE patients, especially in terms of cushingoid features and gain in body weight, 3 and 6 months after initiation of these agents.

METHODS

In both the steroid arms, the following outcome parameters were assessed at 3 and 6 months: (a) cushingoid features by Cushing's Severity Index (CSI) (b) hirsutism by modified Ferriman Gallwey score (c) weight gain by difference (Δ, delta) of weight (in kilograms).

RESULTS

Patients on PDN had 1.6 kg (3.2%) and 2 kg (5.1%) higher median weight gain as compared to those on DFZ at 3 and 6 months respectively ( p = 0.012 and 0.001). PDN caused 10% and 22.2% higher increment in median hirsutism scores as compared to DFZ at 3 months and 6 months follow-up, respectively ( p = 0.004 and 0.002). PDN caused 100% higher increase in median CSI scores than DFZ at 6 months ( p = 0.03). There was no significant difference by generalized estimation equation between the groups with respect to changes in SLEDAI, renal SLEDAI, anti-dsDNA titres and C3/C4 levels. There were two serious infections (requiring hospitalization/intravenous antibiotics) in the PDN group, while none in the DFZ group.

CONCLUSION

Comparable intake and tapering of high dose DFZ and PDN in active SLE revealed 2-fold less weight gain, 2.5-fold less hirsutism and 1.5-fold lower cushingoid severity index as well as lower glycaemic elevation in the DFZ group as compared to PDN group. Both had similar efficacy.

Demodex canis targets TLRs to evade host immunity and induce canine demodicosis

Widespread incidence of Demodex mites throughout the mammalian class and occasional serious and fatal outcomes in dogs warrant an insight into the host-parasite interface especially. Therefore, this study was aimed to unravel the interplay between innate immune response and canine demodicosis. The dogs diagnosed to have natural clinical demodicosis were allocated into two groups; dogs with localized demodicosis (LD) and with generalized demodicosis (GD). The expression of toll-like receptors (TLRs) 2, 4 and 6 genes in peripheral blood mononuclear cells of these dogs was quantified by real-time PCR. Significantly increased TLR2 gene expression, while significantly diminished TLR4 and TLR6 gene expressions were observed in demodicosed dogs (LD and GD) as compared with the healthy ones. Even the expression of TLR2 gene was found to differ significantly between the dogs with LD and GD. Therefore, it can be inferred that clinical demodicosis in dogs is coupled with an up-regulation of TLR2 and down-regulation of TLR4 and TLR6 gene expressions. Overexpression of TLR2 gene might be responsible for Demodex-induced clinical manifestations, while TLR4 and TLR6 gene down-regulations could be the paramount strategy of Demodex mites to elude the host-immune interface.

Discovery of novel drug sensitivities in T-PLL by high-throughput ex vivo drug testing and mutation profiling

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive neoplasm of mature T-cells with an urgent need for rationally designed therapies to address its notoriously chemo-refractory behavior. The median survival of T-PLL patients is <2 years and clinical trials are difficult to execute. Here we systematically explored the diversity of drug responses in T-PLL patient samples using an ex vivo drug sensitivity and resistance testing platform and correlated the findings with somatic mutations and gene expression profiles. Intriguingly, all T-PLL samples were sensitive to the cyclin-dependent kinase inhibitor SNS-032, which overcame stromal-cell-mediated protection and elicited robust p53-activation and apoptosis. Across all patients, the most effective classes of compounds were histone deacetylase, phosphoinositide-3 kinase/AKT/mammalian target of rapamycin, heat-shock protein 90 and BH3-family protein inhibitors as well as p53 activators, indicating previously unexplored, novel targeted approaches for treating T-PLL. Although Janus-activated kinase-signal transducer and activator of transcription factor (JAK-STAT) pathway mutations were common in T-PLL (71% of patients), JAK-STAT inhibitor responses were not directly linked to those or other T-PLL-specific lesions. Overall, we found that genetic markers do not readily translate into novel effective therapeutic vulnerabilities. In conclusion, novel classes of compounds with high efficacy in T-PLL were discovered with the comprehensive ex vivo drug screening platform warranting further studies of synergisms and clinical testing.

Enhanced sensitivity to glucocorticoids in cytarabine-resistant AML

We sought to identify drugs that could counteract cytarabine resistance in acute myeloid leukemia (AML) by generating eight resistant variants from MOLM-13 and SHI-1 AML cell lines by long-term drug treatment. These cells were compared with 66 ex vivo chemorefractory samples from cytarabine-treated AML patients. The models and patient cells were subjected to genomic and transcriptomic profiling and high-throughput testing with 250 emerging and clinical oncology compounds. Genomic profiling uncovered deletion of the deoxycytidine kinase (DCK) gene in both MOLM-13- and SHI-1-derived cytarabine-resistant variants and in an AML patient sample. Cytarabine-resistant SHI-1 variants and a subset of chemorefractory AML patient samples showed increased sensitivity to glucocorticoids that are often used in treatment of lymphoid leukemia but not AML. Paired samples taken from AML patients before treatment and at relapse also showed acquisition of glucocorticoid sensitivity. Enhanced glucocorticoid sensitivity was only seen in AML patient samples that were negative for the FLT3 mutation (P=0.0006). Our study shows that development of cytarabine resistance is associated with increased sensitivity to glucocorticoids in a subset of AML, suggesting a new therapeutic strategy that should be explored in a clinical trial of chemorefractory AML patients carrying wild-type FLT3.

Defining the content of individual physiotherapy and occupational therapy sessions for stroke patients in an inpatient rehabilitation setting. Development, validation and inter-rater reliability of a scoring list

Objective : To develop a valid and reliable scoring list to define the content of individual physiotherapy and occupational therapy sessions for stroke patients in inpatient rehabilitation.

Design : A list was developed based on previous lists, neurological textbooks and recorded therapy sessions. Content validity was verified and inter-rater reliability evaluated on videos of treatment sessions. In each of four rehabilitation centres, a researcher recorded and scored five physiotherapy and five occupational therapy sessions. These 40 treatment sessions were also scored by the first author. The scores of the researchers and first author were statistically compared.

Settings and subjects : Forty stroke patients in four European rehabilitation centres.

Results : The scoring list consists of 49 subcategories, divided into 12 categories: mobilization; selective movements; lying (balance); sitting (balance); standing (balance); sensory and visual perceptual training and cognition; transfers; ambulatory activities; personal activities of daily living; domestic activities of daily living; leisure- and work-related activities; and miscellaneous. Comparing the frequency of occurrence of the categories resulted in intraclass correlation coefficients, indicating high reliability for eight categories, good for one, and fair for two. One category was not observed. Spearman rank correlation coefficients were high to very high for 24 subcategories and moderate for four. Twenty-one subcategories contained too few observations to enable calculation of Spearman rank correlation coefficients. Average point-to-point percentage of agreement in time of the treatment sessions equalled 76.6 ± 16.2%.

Conclusions : The list is a valid and reliable tool for describing the content of physiotherapy and occupational therapy for stroke patients.

Association of oxidative status and semen characteristics with seminal plasma proteins of buffalo semen

To study the influence of season on oxidative status of buffalo semen and their association with semen characteristics and seminal plasma proteins, ejaculates were collected twice a week in winter, summer and rainy seasons from six adult Bhadawari buffalo bulls. The neat semen was analyzed for semen characteristics immediately after collection and oxidative status viz. lipid peroxidation (LPO), catalase (CAT), super oxide dismutase (SOD) activity, and total protein (TP) were estimated in seminal plasma. The protein profiling was carried out by one-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The significant effect of season was observed on TP, SOD activity and % protein fractions of seminal plasma proteins of buffalo bulls. The TP values showed positive correlation with ejaculate volume (EV), sperm concentration (SC), and % live-dead (LD) and negative correlation with progressive motility (PM), and hypo-osmotic swelling test (HOST). The SOD activity showed positive correlation with PM, LD, HOST and % acrosoamal integrity (AI). Besides that, results showed correlation of TP with 6.5, 38 and 66 kDa proteins, LPO with 70, 72, 84 and 86 kDa proteins, CAT with 70 kDa and 86 kDa proteins, and SOD with 6.5, 24.5, 44.5, 70 and 72 kDa proteins. In conclusion, this study indicated that TP and SOD activity of seminal plasma of buffalo bulls were influenced by season and were found to be associated with some of the semen characteristics and expression of seminal plasma proteins.

Novel drug candidates for blast phase chronic myeloid leukemia from high-throughput drug sensitivity and resistance testing

Chronic myeloid leukemia in blast crisis (CML BC) remains a challenging disease to treat despite the introduction and advances in tyrosine kinase inhibitor (TKI) therapy. In this study we set out to identify novel candidate drugs for CML BC by using an unbiased high-throughput drug testing platform. We used three CML cell lines representing different types of CML blast phases (K562, EM-2 and MOLM-1) and primary leukemic cells from three CML BC patients. Profiling of drug responses was performed with a drug sensitivity and resistance testing platform comprising 295 anticancer agents. Overall, drug sensitivity scores and the drug response profiles of cell line and primary cell samples correlated well and were distinct from other types of leukemia samples. The cell lines were highly sensitive to TKIs and the clinically TKI-resistant patient samples were also resistant ex vivo. Comparison of cell line and patient sample data identified new candidate drugs for CML BC, such as vascular endothelial growth factor receptor and nicotinamide phosphoribosyltransferase inhibitors. Our results indicate that these drugs in particular warrant further evaluation by analyzing a larger set of primary patient samples. The results also pave way for designing rational combination therapies.

Regulatory and effector T cells changes in remission and resistant state of childhood nephrotic syndrome

Idiopathic minimal change disease is a disorder of T-cell dysfunction. The relative predominance of regulatory T cells (Tregs), Th1, and Th2 cells in nephrotic syndrome (NS) remains controversial. Imbalance in peripheral blood regulatory and effector T cells (Teff) are linked to cell mediated immune response and may be associated with steroid response in NS. Peripheral blood CD4 + CD25 + FoxP3 + (Tregs), CD4 + IFN-γ⁺ (Th1), and CD4 + IL-4 + (Th2) lymphocytes were analyzed in 22 steroid-sensitive NS (SSNS) patients in sustained remission, 21 steroid-resistant NS (SRNS) and 14 healthy controls. The absolute percentage values and ratio of Th1/Tregs, Th2/Tregs, and Th1/Th2 were compared between SSNS, SRNS and control subjects. The percentage of Tregs was lower in SRNS patients (P = 0.001) compared with that of SSNS and healthy control. The percentage of Th1 cells was higher in SRNS (P = 0.001) compared to that of SSNS patients; however, it was similar to healthy controls (P = 1.00). The percentage of Th2 cells in SRNS (P = 0.001) was higher as compared to SSNS and controls. The ratio of Th1/Treg cells in SRNS (P = 0.001) was higher as compared to SSNS patients and controls. The ratio of Th2/Treg was also higher in SRNS as compared to SSNS and controls. The ratio of Th1/Th2 cells in SSNS, SRNS, and healthy controls were similar. The cytokines secretion complemented the change in different T-cell subtypes in SSNS, SRNS and healthy controls. However, the IFN-γ secretion in healthy controles was low inspite of similar percentage of Th1 cells among SRNS cases. We conclude that greater ratio of Tregs compared to that Th1 and Th2 favor steroid sensitivity and reverse ratio results in to SRNS. The difference in ratio is related to pathogenesis or it can be used as marker to predict steroid responsiveness needs further evaluation.

Normal fetal nasal bone length at 14 to 28 weeks of gestation

The fetal nasal bone length (FNBL) is a recent sonographic marker included in second trimester genetic sonography which varies with race and ethnicity. The importance of measuring FNBL is in the prenatal diagnosis of Down's syndrome (DS), the most common chromosomal abnormality. Nasal bone hypoplasia or absence is one of the frequent features of DS. Different studies conducted in different parts of the world have established FNBL in different races. But, reference values for normal fetal nasal bone length are yet to be established for Nepalese population. So, the aim of this study was to determine normal FNBL in second trimester. Objective was to create normal reference values for fetal nasal bone in Nepalese population. A cross sectional study was carried out on 150 second trimester pregnancy cases referred for antenatal ultrasound to Department of Radiology at Nepal Medical College and Teaching Hospital between May 2014 and July 2014. Cases included all the clinically normal second trimester pregnancy in which fetal nasal bone could be visualized in midsagittal plane. Table demonstrating normal FNBL corresponding to weeks of gestation was generated using IBM SPSS Statistics Version 20. There was linear increase in mean FNBL with gestational age. Minimum mean FNBL was 2.93 mm at 14 weeks and maximum was 7.89 mm at 27 weeks. Age of patients ranged from 17 to 35 years. Normal FNBL values in Nepalese population corroborates with those published in Western literature but with variation. Hence, reference values for local population become more relevant for antenatal ultrasound practices in Nepal.

Prospective blood pressure measurement in renal transplant recipients

Blood pressure (BP) control at home is difficult when managed only with office blood pressure monitoring (OBPM). In this prospective study, the reliability of BP measurements in renal transplant patients with OBPM and home blood pressure monitoring (HBPM) was compared with ambulatory blood pressure monitoring (ABPM) as the gold standard. Adult patients who had living-related renal transplantation from March 2007 to February 2008 had BP measured by two methods; OBPM and ABPM at pretransplantation, 2^nd, 4^th, 6^th, and 9^th months and all the three methods: OBPM, ABPM, and HBPM at 6 months after transplantation. A total of 49 patients, age 35 ± 11 years, on prednisolone, tacrolimus, and mycophenolate were evaluated. A total of 39 were males (79.6%). Systolic BP (SBP) and diastolic BP (DBP) measured by OBPM were higher than HBPM when compared with ABPM. When assessed using OBPM and awake ABPM, both SBP and DBP were significantly overestimated by OBPM with mean difference of 3-12 mm Hg by office SBP and 6-8 mm Hg for office DBP. When HBPM was compared with mean ABPM at 6 months both the SBP and DBP were overestimated by and 7 mm Hg respectively. At 6 months post transplantation, when compared with ABPM, OBPM was more specific than HBPM in diagnosing hypertension (98% specificity, Kappa: 0.88 vs. 89% specificity, Kappa: 0.71). HBPM was superior to OBPM in identifying patients achieving goal BP (89% specificity, Kappa: 0.71 vs. 50% specificity Kappa: 0.54). In the absence of a gold standard for comparison the latent class model analysis still showed that ABPM was the best tool for diagnosing hypertension and monitoring patients reaching targeted control. OBPM remains an important tool for the diagnosis and management of hypertension in renal transplant recipients. HBPM and ABPM could be used to achieve BP control.

Anticancer compound ABT-263 accelerates apoptosis in virus-infected cells and imbalances cytokine production and lowers survival rates of infected mice

ABT-263 and its structural analogues ABT-199 and ABT-737 inhibit B-cell lymphoma 2 (Bcl-2), BCL2L1 long isoform (Bcl-xL) and BCL2L2 (Bcl-w) proteins and promote cancer cell death. Here, we show that at non-cytotoxic concentrations, these small molecules accelerate the deaths of non-cancerous cells infected with influenza A virus (IAV) or other viruses. In particular, we demonstrate that ABT-263 altered Bcl-xL interactions with Bcl-2 antagonist of cell death (Bad), Bcl-2-associated X protein (Bax), uveal autoantigen with coiled-coil domains and ankyrin repeats protein (UACA). ABT-263 thereby activated the caspase-9-mediated mitochondria-initiated apoptosis pathway, which, together with the IAV-initiated caspase-8-mediated apoptosis pathway, triggered the deaths of IAV-infected cells. Our results also indicate that Bcl-xL, Bcl-2 and Bcl-w interact with pattern recognition receptors (PRRs) that sense virus constituents to regulate cellular apoptosis. Importantly, premature killing of IAV-infected cells by ABT-263 attenuated the production of key pro-inflammatory and antiviral cytokines. The imbalance in cytokine production was also observed in ABT-263-treated IAV-infected mice, which resulted in an inability of the immune system to clear the virus and eventually lowered the survival rates of infected animals. Thus, the results suggest that the chemical inhibition of Bcl-xL, Bcl-2 and Bcl-w could potentially be hazardous for cancer patients with viral infections.

In Vitro Anticancer Activity of the Root, Stem and Leaves of Withania Somnifera against Various Human Cancer Cell Lines

Withania Somnifera Dunal know as Ashwagandha belong Solanaceae family. It is extensively used in most of the Indian herbal pharmaceuticals and nutraceuticals. The current study, evaluate in vitro cytotoxicity in 50% ethanol extract of root, stem and leaves of Withania Somnifera against five human cancer cell lines of four different tissues i.e. PC-3, DU-145 (prostrate), HCT-15 (colon), A-549 (lung) and IMR-32 (neuroblastoma). Root, stem and leaves extracts showed cytotoxicity activity ranging 0-98% depending on the cell lines but maximum activity was found in 50% ethanol extract of leaves of Withania Somnifera. Ethanol extract of leaves obtained from treatments T2, T3, T4 and T5 showed strong activity against PC-3 and HCT-15 with 80-98% growth inhibition, while the 50% ethanol extract of leaves from T1 treatment showed a minimum of 39% and T3 treatment showed a maximum of 98% growth inhibition against HCT-15. This investigation is the first report of the anticancer activity in various parts of Withania Somnifera cultivated in fly ash amended soil.

Need of Improvement in Emergency Medical Service in Urban Cities

Introduction: An effective Emergency Medical Service system does not exist in Nepal. For an effective EMS system to be developed the scale of the problem and the existing facilities need to be studied. Methods: Prospective observational study was carried out on 1964 patients attending Emergency Department at Patan Hospital during one month period of September 2006. The patients were specifically enquired on mode of transport used, place of origin and whether they called for an ambulance or not. Patients triage category at the time of triaging was also noted. Information on ambulance service were collected by direct interview with the service providers and the total number of patients attending Emergency Departments daily were collected from the major hospitals of the urban Lalitpur and Kathmandu. MS Excel and SPSS software were used for data entry, editing and analysis.Results: Total 9.9% patients arrived in ambulance whereas 53.6% came in a Taxi, 11.4% came in private vehicle, 13.5 % came by bus, 5.4% came by bike and the rest 6.2% came by other modes of transportation. Only 13.5% of triage category I patients took the ambulance. There were 31 service providers with 49 ambulances and 720 patients per day attend Emergency Departments in the surveyed area. Conclusions: Very less number of patients use the ambulance service for emergency services. The available ambulances are not properly equipped and do not have trained staff and as such are only a means of transportation to the hospitals of urban Lalitpur and Kathmandu.Key Words: ambulance, emergency medical service, para-medics, triage Need of Improvement in Emergency Medical Service in Urban Cities Gongal R,1Dhungana B,1Regmi S,1Nakarmi M,2Yadav B11Patan Hospital, Lalitpur, Nepal, 2Health Care Foundation, Kathmandu, NepalCorrespondence:Dr. Rajesh GongalDepartment of SurgeryPatan Hospital, Patan, Nepal.Email: rajgongal@yahoo.comORIGINAL ARTICLE J Nepal Med Assoc 2009;48(174):139-43INTRODUCTIONThe sophisticated Emergency Medical Service (EMS) is limited to developed country only. Many developing countries are now slowly developing such system although most services are localized to the urban areas.1-5 Although inadquate ambulance services are available in the capital city of Nepa

Need of improvement in emergency medical service in urban cities

INTRODUCTION

An effective Emergency Medical Service system does not exist in Nepal. For an effective EMS system to be developed the scale of the problem and the existing facilities need to be studied.

METHODS

Prospective observational study was carried out on 1964 patients attending Emergency Department at Patan Hospital during one month period of September 2006. The patients were specifically enquired on mode of transport used, place of origin and whether they called for an ambulance or not. Patients triage category at the time of triaging was also noted. Information on ambulance service were collected by direct interview with the service providers and the total number of patients attending Emergency Departments daily were collected from the major hospitals of the urban Lalitpur and Kathmandu. MS Excel and SPSS software were used for data entry, editing and analysis.

RESULTS

Total 9.9% patients arrived in ambulance whereas 53.6% came in a Taxi, 11.4% came in private vehicle, 13.5 % came by bus, 5.4% came by bike and the rest 6.2% came by other modes of transportation. Only 13.5% of triage category I patients took the ambulance. There were 31 service providers with 49 ambulances and 720 patients per day attend Emergency Departments in the surveyed area.

CONCLUSIONS

Very less number of patients use the ambulance service for emergency services. The available ambulances are not properly equipped and do not have trained staff and as such are only a means of transportation to the hospitals of urban Lalitpur and Kathmandu.

Flavanone glycosides from Alhagi pseudalhagi

Two new flavanone glycosides, alhagitin and alhagidin, have been isolated from the whole plant of Alhagi pseudalhagi and their structures established respectively as naringenin 5-methyl ether 4'-glucoside and hesperitin 7-galactosyl(1-->2)[rhamnosyl(1-->6)]glucoside by chemical and spectroscopic methods.

The mechanism and inheritance of adult plant leaf rust resistance in 12 wheat lines

Twelve lines of wheat (Triticum aestivum L.) were developed that had susceptible infection types to leaf rust (Puccinia recondita Rob. ex Desm. f.sp. tritici) race UN 15 in the seedling stage but were resistant in the adult plant stage in the field. The lines were developed from four crosses, each involving four parents (eight in total) that had originally been selected for adult plant or field resistance to stem rust (Puccinia graminis Pers. f.sp. tritici Eriks, and Henn.). The objectives of the present study were to determine the mechanism of resistance to leaf rust and its inheritance in the 12 lines. The 12 lines were grown in an artificially inoculated field nursery in Saskatoon, coefficients of infection (CI) were determined at four dates, and the areas under the disease progress curve (AUDPC) were calculated. Four representative lines were grown in a growth chamber to measure the latent period and pustule size at the two-leaf and flag-leaf stages. Eight lines were crossed and backcrossed to a susceptible check and the parents, F1, F2, F3, and BC1F2 generations were grown in a field nursery. The 12 lines showed wide ranges in CI and AUDPC but all were significantly more resistant than the susceptible check. The four lines studied in the growth chamber had longer latent periods and smaller pustules than the susceptible check at both stages. The differences tended to be greater at the flag-leaf stage. The inheritance studied showed that resistance was recessive or partially recessive and was controlled by two or more genes in each line of the eight lines. In three of the eight lines, Lr34 may be one of the genes and in the other five both Lr13 and Lr34 could be present. However, additional genes are clearly involved. A single gene by itself had only a small effect, but in two and three gene combinations the effects appeared to be greater. This type of resistance appears to occur frequently and may be durable because its complex inheritance may make it more difficult for the rust fungus to overcome. It should be used in breeding wheat for areas where leaf rust is a major problem.