Reversible cerebral vasoconstriction syndrome in Guillain-Barre syndrome: a case report and literature review

BACKGROUND

Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by transient constriction of cerebral arteries, leading to severe headache and potential complications. The association between RCVS and Guillain-Barre syndrome (GBS) is rare and poorly understood and warrants further investigation.

METHODS

A detailed case of RCVS in a patient with GBS was presented, followed by a comprehensive literature review. PubMed, Embase, and Google Scholar were searched for relevant cases and studies.

RESULTS

The case involved a 62-year-old woman with GBS who developed RCVS. The literature review identified three additional reported cases. RCVS in GBS primarily affected middle-aged women and presented with a variety of neurological symptoms. Neuroimaging showed reversible vasoconstriction in the cerebral arteries, along with other complications such as posterior reversible encephalopathy syndrome, subarachnoid hemorrhage, and infarcts. While the treatment for GBS consisted mainly of intravenous immunoglobulin, specific treatments for RCVS remain unclear.

CONCLUSIONS

The coexistence of RCVS and GBS is a rare occurrence. RCVS in GBS may result from the disruption of cerebral vascular tone regulation, possibly influenced by GBS-related dysautonomia and consequent high blood pressure. Recognizing RCVS in GBS patients is critical for appropriate management.

Acute Hemorrhagic Encephalomyelitis in the Context of MOG Antibody-Associated Disease. Comment on Chen et al. Rapid Progressive Fatal Acute Hemorrhagic Encephalomyelitis. Diagnostics 2023, 13, 2481

The study by Chen et al. of a 56-year-old man diagnosed with acute hemorrhagic encephalomyelitis (AHEM) had a significant impact on us. The authors provided a comprehensive account of their diagnostic journey and emphasized the need to differentiate myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) from AHEM. However, recent research suggests that AHEM may not be an isolated entity, but rather a phenotype within MOGAD. The patient's clinical presentation included MRI brain lesions characteristic of MOGAD in addition to hemorrhagic abnormalities. These findings raise the possibility that AHEM in this case represents a MOGAD phenotype. In conclusion, it is important to recognize the potential association between AHEM and MOGAD, especially when distinct MOGAD brain MRI patterns are present, as in this case.

Serum neurofilament light chain levels are correlated with the infarct volume in patients with acute ischemic stroke

Neurofilament light chains (NfLs) are promising biomarkers of neuroaxonal damage in stroke patients. We investigated the correlations between NfL levels and infarct volume, initial stroke severity, and functional outcomes at discharge in patients with acute ischemic stroke. We prospectively included 15 patients with first-ever acute ischemic stroke and 8 age- and sex-matched healthy controls without other neurological disorders. Serum NfL levels were measured using the single-molecule array (Simoa) technique twice within 24 hours of admission (NfL1D) and on the seventh hospital day (NfL7D) in patients with stroke and once in healthy controls. We assessed the infarct volume on diffusion-weighted magnetic resonance imaging using the free software ITK-SNAP. Serum NfL1D levels in stroke patients were significantly higher (28.4 pg/mL; interquartile range [IQR], 43.0) than in healthy controls (14.5 pg/mL; IQR, 3.2; P = .005). Temporal pattern analyses demonstrated that NfL7D levels were increased (114.0 pg/mL; IQR, 109.6) compared to NfL1D levels in all stroke patients (P = .001). There was a strong correlation between NfL7D levels and infarct volume (R = 0.67, P = .007). The difference between NfL1D and NfL7D (NfLdiff levels) was strongly correlated with the infarct volume (R = 0.63; P = .013). However, there was no statistically significant correlation between NfL levels and the initial stroke severity or functional outcomes at discharge. NfL levels in the subacute stage of stroke and the NfL difference between admission and 7th day of hospital were correlated with infarct volume in patients with acute ischemic stroke.

Reperfusion Therapy in Acute Ischemic Stroke with Active Cancer: A Meta-Analysis Aided by Machine Learning

OBJECTIVES

While the prevalence of active cancer patients experiencing acute stroke is increasing, the effects of active cancer on reperfusion therapy outcomes are inconclusive. Thus, we aimed to compare the safety and outcomes of reperfusion therapy in acute stroke patients with and without active cancer.

MATERIALS AND METHODS

A comprehensive literature search was conducted for studies comparing the effects of intravenous thrombolysis (IVT) or endovascular treatment (EVT) in ischemic stroke patients with and without active cancer. The literature was screened using both a manual and machine learning algorithm approach. The outcomes evaluated were symptomatic intracerebral hemorrhage (sICH), all-type intracerebral hemorrhage (aICH), successful recanalization, favorable outcomes (modified Rankin Scale, 0-2), and mortality. We calculated the pooled odds ratio (OR) and 95% confidence interval (CI) using the random-effects model from the included studies.

RESULTS

Seven studies were analyzed in this meta-analysis. IVT (n = 1012) was associated with an increased risk of sICH (OR, 9.80; 95% CI, 3.19-30.13) in the active cancer group. However, no significant differences in aICH, favorable outcomes, and mortality were found between groups. Although sICH and successful recanalization in the EVT group (n = 2496) were similar, we observed fewer favorable outcomes (OR, 0.55; 95% CI, 0.33-0.93) and a high prevalence of mortality (OR, 2.91; 95% CI, 1.89-4.47) in the active cancer group.

CONCLUSIONS

Reperfusion therapy may benefit selected patients with acute ischemic stroke with active cancer, considering the comparable clinical outcomes of IVT and procedure-related outcomes of EVT. These results should be cautiously interpreted and confirmed in future well-designed large-scale studies.

Initiation of Guideline-Matched Oral Anticoagulant in Atrial Fibrillation-Related Stroke

BACKGROUND AND PURPOSE

To evaluate the outcome events and bleeding complications of the European Society of Cardiology (ESC) guideline-matched oral anticoagulant therapy for patients with acute ischemic stroke and atrial fibrillation (AF).

METHODS

Patients with acute ischemic stroke and AF from a nationwide multicenter registry (Korean ATrial fibrillaTion EvaluatioN regisTry in Ischemic strOke patieNts [K-ATTENTION]) between January 2013 and December 2015 were included in the study. Patients were divided into the ESC guideline-matched and the non-matched groups. The primary outcome was recurrence of any stroke during the 90-day follow-up period. Secondary outcomes were major adverse cerebrovascular and cardiovascular events, ischemic stroke, intracranial hemorrhage, acute coronary syndrome, allcause mortality, and major hemorrhage. Propensity score matching and logistic regression analyses were performed to assess the effect of the treatments administered.

RESULTS

Among 2,321 eligible patients, 1,126 patients were 1:1 matched to the ESC guidelinematched and the non-matched groups. As compared with the non-matched group, the ESC guideline-matched group had a lower risk of any recurrent stroke (1.4% vs. 3.4%; odds ratio [OR], 0.41; 95% confidence interval [CI], 0.18 to 0.95). The risk of recurrent ischemic stroke was lower in the ESC guideline-matched group than in the non-matched group (0.9% vs. 2.7%; OR, 0.32; 95% CI, 0.11 to 0.88). There was no significant difference in the other secondary outcomes between the two groups.

CONCLUSIONS

ESC guideline-matched oral anticoagulant therapy was associated with reduced risks of any stroke and ischemic stroke as compared with the non-matched therapy.

Statin Effects in Atrial Fibrillation-Related Stroke: A Systematic Review and Meta-Analysis

Background: Statins lower the risk of recurrent stroke and mortality and improve outcomes in patients with ischemic stroke. However, the effects of statins on atrial fibrillation (AF)-related stroke are not well-established. Our study aims to investigate the effects of statin therapy on the clinical outcomes in patients with AF-related stroke.

Methods: Electronic databases (MEDLINE, Embase, and Scopus) were searched for previous studies on the effects of pre- and post-stroke statins on the clinical outcomes in AF-related stroke patients. The primary outcome was all-cause mortality. Secondary outcomes included recurrent ischemic stroke, acute coronary events, major adverse cardiovascular events (MACE), and short-term functional outcomes. We extracted hazard ratios (HRs) or odds ratios (ORs) with 95% confidence interval (CI) from each study and pooled them through a meta-analysis.

Results: A total of eight studies (five on post-stroke statins and three on pre-stroke statins) with 12,216 patients were included in the analysis. Post-stroke statin therapy reduced the risk of all-cause mortality (HR, 0.63; 95% CI, 0.55–0.74). This beneficial effect was sustained regardless of statin intensity. However, no significant associations were observed between statin therapy and a reduction in the risk of recurrent ischemic stroke, acute coronary events, or MACE. Pre-stroke statin use was associated with a lower risk of poor short-term functional outcomes (OR, 0.63; 95% CI, 0.47–0.85).

Conclusions: Statin therapy for AF-related stroke may reduce all-cause mortality and improve functional outcomes. Randomized controlled studies are warranted to confirm the effects of statins on the outcomes of AF-related stroke.

Predictive value of free fatty acid levels in embolic stroke of undetermined source: A retrospective observational study

The present study aimed to investigate the predictive value of free fatty acid (FFA) in embolic stroke of undetermined source (ESUS) according to the presence of potential embolic sources (PES) after extensive etiologic evaluation.This was a retrospective observational study based on a single-center registry from January 2011 to July 2017. Stroke subtypes were determined through laboratory findings, brain, and angiographic imaging, carotid ultrasonography, transthoracic echocardiography, and 24-hour Holter monitoring. If ESUS was suspected, transesophageal echocardiography was additionally performed. Patients were classified into ESUS with PES and ESUS without PES. PES included mitral annular calcification, mitral valve prolapse, patent foramen ovale, atrial septal aneurysm, spontaneous echo contrast, ventricular aneurysm, and high-risk plaques of aortic arch, or carotid bulb. We compared clinical and laboratory findings between the two groups.Of a total of 110 ESUS patients, 61 patients (55.5%) had no PES. Patients with ESUS without PES had higher levels of serum FFA, systolic blood pressure, diastolic blood pressure (DBP), and left atrial (LA) enlargement compared with those of ESUS with PES. Multivariable analysis demonstrated that the FFA level, DBP, and LA volume index were associated with ESUS without PES [odds ratio (OR) 1.038, 95% confidence interval (CI) 1.019-1.058 for FFA/10 μEq/L, OR 1.414, 95% CI 1.037-1.928 for DBP/10 mm Hg, and OR 1.073, 95% CI 1.009-1.141 for LA volume index].Higher levels of FFA, DBP, and LA volume index are associated with ESUS without PES, highlighting the need to identify the role of these markers in ESUS through further large-scale, multi-center and prospective studies.

Lower Glucose Level Associated With Increased Risk for Post-Dural Puncture Headache

OBJECTIVE AND BACKGROUND

Post-dural puncture headache is the most common significant adverse event following lumbar puncture. In this study, we investigated the possible systemic factors associated with risk for post-dural puncture headache (PDPH).

METHODS

We performed a retrospective cohort study in 969 patients who underwent diagnostic lumbar puncture following a standardized protocol. We compared the clinical and laboratory profiles of the post-dural puncture headache group and non-headache group. We also identified independent factors associated with the incidence of post-dural puncture headache.

RESULTS

A total of 48 patients (5%) reported headache; 12 of these patients (25%) received a therapeutic epidural blood patch and the remaining 36 patients improved with conservative treatment. After adjusting for other variables that could be related to PDPH, we found that the development of post lumbar puncture headache was independently associated with age (OR: 0.97, 95% CI: 0.95-0.99, P = .001) and serum glucose levels (OR: 0.98, 95% CI: 0.97-0.99, P = .008).When the patients were classified by age, serum glucose levels were persistently lower in patients with PDPH vs those patients without PDPH in all age groups, with more clearly significant differences observed in the elderly (age <30 years, 103.4 mg/dL vs 106.3 mg/dL, P = .716; >60 years, 111.8 mg/dL vs 137.3 mg/dL, P = .023).

CONCLUSIONS

Low glucose levels were inversely associated with risk for post-dural puncture headache. Patients with low serum glucose should be carefully monitored for headache after lumbar puncture.

Abstract TP435: Oral Anticoagulant Therapy Adherent to ESC Guidelines Reduces the Risk of Recurrent Stroke in Patients With Atrial Fibrillation

Introduction: Oral anticoagulant therapy is the primary treatment for the prevention of recurrent ischemic stroke in patients with atrial fibrillation (AF). Early anticoagulant therapy can be beneficial for the prevention of recurrent ischemic stroke, however, also can provoke symptomatic intracranial hemorrhage. This study aims to evaluate the efficacy and safety of standard oral anticoagulant therapy adherent to the European Society of Cardiology (ESC) guidelines compared to early oral anticoagulant therapy.

Methods: Acute ischemic stroke patients with AF were included from a nationwide multicenter registry (K-ATTENTION). The primary outcome was recurrent all-type stroke during 90 days of follow-up. Secondary outcomes were major adverse cardiovascular events (MACE), ischemic stroke, intracranial hemorrhage, acute coronary syndrome, all-cause death, and major hemorrhage. The propensity score was used to match the baseline characteristics between the two treatment groups.

Results: Among 2,321 eligible patients, 532 patients with standard anticoagulation were matched to 532 patients with early anticoagulation. Eight participants (1.5%) with standard anticoagulation had recurrence of all-type stroke compared with 19 (3.5%) of participants with early anticoagulation (odds ratio [OR], 0.41; 95% confidence interval [CI], 0.18-0.95; P=0.038). Standard anticoagulation was also associated with reduced risk of recurrent ischemic stroke (OR, 0.30; 95% CI, 0.11-0.82; P=0.019). Other secondary outcomes, including intracranial hemorrhage and major hemorrhage, appeared not to be informative.

Conclusions: In conclusion, standard oral anticoagulant therapy adherent to ESC guidelines reduces the risk of recurrent all-type stroke and ischemic stroke compared to early oral anticoagulant therapy.

Prestroke Antiplatelet Agents in First-Time Ischemic Stroke Are Related to Subtypes

BACKGROUND

It is not well known whether prestroke antiplatelet agents (PAs) are associated with the subtypes of ischemic stroke.

METHODS

We screened patients in a hospital-based stroke registry. Patients who were admitted with a diagnosis of first-time ischemic stroke within 5 days of symptom onset were included. Ischemic stroke subtypes were classified in accordance with the Trial of ORG 10172 in Acute Stroke Treatment classification based on stroke mechanism: large-artery atherosclerosis (LA), cardioembolism (CE), small vessel occlusion (SVO), other determined (OC) or undetermined causes (UC). Multinomial logistic regression analyses were performed to evaluate the effect of PA on stroke subtypes before and after propensity score matching.

RESULTS

Among 3,025 patients, 748 (24.7%) were taking antiplatelet agents prior to stroke. After propensity score matching, 1,190 patients were ultimately included. The PA group was associated with strokes caused by SVO rather than LA in multinomial logistic regression of an unmatched dataset. However, multivariable analysis after propensity score matching demonstrated that PA use was associated with a higher probability of SVO and CE (OR 2.05, p < 0.001 and OR 1.62, p = 0.05, respectively) compared with LA.

CONCLUSIONS

PAs were associated with specific index stroke subtypes.

Power motion-mode Doppler signature: a useful tool for assessing middle cerebral artery stenosis

PURPOSE

To identify power motion-mode Doppler (PMD) patterns and assess their diagnostic value for the diagnosis of middle cerebral artery (MCA) stenosis.

METHODS

Retrospective analyses of PMD data were performed for the identification of specific patterns related to MCA stenosis. The interrater reliability and the validity of these patterns were studied, using magnetic resonance angiography and conventional transcranial Doppler sonography as gold standards.

RESULTS

Three PMD patterns were identified: the so-called black-hole, the white-hole, and the diastolic-band patterns in 58 among 178 MCAs. The mean flow velocity was significantly higher in arterial segments with the black-hole patterns and lower in segments with the diastolic-band pattern compared with the segments with normal patterns. The interrater reliability was good for each pattern. The black-hole pattern or its combination with the white-hole pattern showed the highest validity.

CONCLUSION

Despite some limitations, the black-hole PMD pattern or its combination with the white-hole pattern appeared as a reliable and valid marker for the diagnosis of MCA stenosis.

Abstract 3305: Intensive Lipid-lowering and Early Functional Outcome in Acute Ischemic Stroke: Propensity Score Matching Analysis

Background This retrospective case-control study was designed to compare the effect of early high-dose atorvastatin treatment on early functional outcome in acute ischemic stroke patients using propensity score matching (PSM).

Study design and population Acute ischemic stroke patients were selected from prospectively collected hospital-based stroke registry. Because the purpose of this study was comparing two treatment strategies for statin treatment, patients with cardioembolic stroke subtype or other-etiology were excluded. Patients were allocated into two groups: Intensive treatment group (atorvastatin 80mg; IT) and conventional treatment group (atorvastatin 10-40mg or other lipid-lowering agent; CT). All the patients were prescribed for aspirin 300mg at admission except for the patients who were considered for thrombolysis. After admission, the patients were prescribed for antithrombotics according to the clinical decision of the attending physician. All other practice guidelines except management of dyslipidemia were followed for previously published guidelines for management of stroke patients. Detailed demographic factors, vascular risk factors, laboratory parameters and vascular imaging were recorded. The end points were composed of two parameters. First, early neurological deterioration (END) defined as 4 points or more deterioration of National Institute of Health Stroke Score (NIHSS) from admission to the seventh hospital day. In case of discharge before the seventh hospital day, NIHSS at discharge was substituted for that of the seventh hospital day. Second, favorable outcome was defined as 0-2 of modified Rankin Score (mRS) measured at 3 months from the onset of stroke. Because baseline characteristics between the groups was supposed to be different, propensity score matching was performed to adjust for potential selection biases and confounding. A logistic regression model was fitted relating treatment strategies (IT and CT) to pretreatment patient characteristics. For the comparison between IT and CT in terms of END and favorable outcome, McNemar test were performed.

Results: Among the study population, data of 178 patients for IT and 218 patients for CT were collected. Between the groups, history of previous stroke, TOAST classification, and previous medication of clopidogrel showed significant difference. There was no significant difference of 90-day favorable outcome and END. After PSM, 116 patients for each group were selected. There was no significant difference of baseline characteristics between the groups after PSM. There was no significant difference between IT and CT in terms of 90-day favorable outcome (75.3% in IT and 78.4% in CT, p = 0.457) and END (IT 72.3%, CT 78.6%, p = 0.097).

Conclusion In this study, effect of intensive lipid-lowering treatment in acute stroke patients was negligible in terms of early functional outcome.

Joubert syndrome presenting with young-age onset ischemic stroke: a possible etiologic association

Joubert syndrome is a rare genetic disorder of childhood that is characterized by hypoplasia or agenesis of the cerebellar vermis in addition to brainstem malformations. Ataxia, hypotonia, developmental delay, and apnea-hyperpnea are the most prominent clinical symptoms of Joubert syndrome, but this condition can also affect multiple organs, making the clinical phenomenology of Joubert syndrome quite diverse. Seizures are the most common neurological complications of Joubert syndrome, but its neurological sequelae are poorly described because Joubert syndrome is very rare. Here we report an acute ischemic stroke in a 21-year-old woman with Joubert syndrome who had no conventional risk factors for early onset cerebrovascular disease. To date, this is the first report of an ischemic stroke in a patient with Joubert syndrome, and we believe this case may suggest an association between Joubert syndrome and extremely early onset cerebrovascular disease.

Neoplastic meningitis presenting with acute cerebellar ataxia

Acute cerebellar ataxia is a rare initial presenting feature of neoplastic meningitis (NM), particularly in gastric cancer. The authors report a 61-year-old woman with acute cerebellar ataxia secondary to NM from gastric cancer, which was not accompanied by other symptoms commonly associated with NM at initial presentation. It is suggested that NM should be considered in the differential diagnosis of cancer patients with acute cerebellar ataxia.

Transient increase in intrathoracic pressure as a contributing factor to cardioembolic stroke

Background

The hemodynamic effects of increased intrathoracic pressure (ITP) have been the focus of many investigations. However, very little is known about the effects of elevated ITP on the occurrence of stroke.

Case Report

Four young patients with a cardioembolic source of stroke were examined. In all cases the stroke was preceded by an increase in ITP that occurred during coughing, vomiting, or sexual intercourse.

Conclusions

We suggest that cardioembolic stroke is facilitated by situations in which ITP is elevated.

Marker-assisted selection for identification of plant regeneration ability of seed-derived calli in rice (Oryza sativa L.)

Quantitative trait loci (QTL), associated with the ability of plant regeneration from seed-derived callus of rice, were mapped using a recombinant inbred (RI) population from Milyang 23/Gihobyeo. Each flanking marker, RZ474 and RZ575, tightly linked to two QTLs (qSGR-3-1 and qSGR-3-2) that are located on chromosome 3 was used in marker-assisted selection (MAS). These markers were tested on IR 36/MG RI036 (F3), Milyang 23/MG RI036 (F3), and forty-one rice cultivars. A restriction fragment length polymorphism (RFLP) marker, RZ575, that is located on chromosome 3 could effectively differentiate lines with high and poor regeneration ability, based on marker genotypes. This marker might be applicable for screening rice germplasms with high regeneration ability. Its introgression into elite lines might also be valuable in breeding programs to develop highly responsive genotypes to tissue culture.

Quantitative trait loci mapping associated with plant regeneration ability from seed derived calli in rice (Oryza sativa L.)

Quantitative trait loci (QTLs), which are associated with the ability of plant regeneration from seed derived calli, were detected using a recombinant inbred (RI) population from a cross between 'Milyang 23 (toingil)' and 'Gihobyeo (japonica)' in rice (Oryza sativa L.). A tongil type cultivar, 'Milyang 23', has a lower frequency of callus induction and plant regeneration than those of japonica 'Gihobyeo'. Transgressive segregations were observed for the callus induction rate and plant regeneration ability from seed derived calli of the RI population. An interval mapping analysis was used to identify the QTL controlling the plant regeneration ability. Two QTLs for the callus induction rate were detected on chromosomes 1 and 2, explaining the 10.9% total phenotypic variation. Four QTLs that are associated with the plant regeneration ability were located on chromosomes 2, 3, and 11, accounting for 25.7% of the total phenotypic variation.

Analysis of expressed sequence tags from Brassica rapa L. ssp. pekinensis

Non-redundant expressed sequence tags (ESTs) were generated from six different organs at various developmental stages of Chinese cabbage, Brassica rapa L. ssp. pekinensis. Of the 1,295 ESTs, 915 (71%) showed significantly high homology in nucleotide or deduced amino acid sequences with other sequences deposited in databases, while 380 did not show similarity to any sequences. Briefly, 598 ESTs matched with proteins of identified biological function, 177 with hypothetical proteins or non-annotated Arabidopsis genome sequences, and 140 with other ESTs. About 82% of the top-scored matching sequences were from Arabidopsis or Brassica, but overall 558 (43%) ESTs matched with Arabidopsis ESTs at the nucleotide sequence level. This observation strongly supports the idea that gene-expression profiles of Chinese cabbage differ from that of Arabidopsis, despite their genome structures being similar to each other. Moreover, sequence analyses of 21 Brassica ESTs revealed that their primary structure is different from those of corresponding annotated sequences of Arabidopsis genes. Our data suggest that direct prediction of Brassica gene expression pattern based on the information from Arabidopsis genome research has some limitations. Thus, information obtained from the Brassica EST study is useful not only for understanding of unique developmental processes of the plant, but also for the study of Arabidopsis genome structure.

Hormonal cross-talk between auxin and ethylene differentially regulates the expression of two members of the 1-aminocyclopropane-1-carboxylate oxidase gene family in rice (Oryza sativa L.)

Two cDNA clones, pOS-ACO2 and pOS-ACO3, encoding 1-aminocyclopropane-1-carboxylate (ACC) oxidase were isolated from rice seedling cDNA library. pOS-ACO3 is a 1,299 bp full-length clone encoding 321 amino acids (Mr=35.9 kDa), while pOS-ACO2 is 1,072 bp long and is a partial cDNA clone encoding 314 amino acids. These two deduced amino acid sequences share 70% identity, and display a high degree of sequence identity (72-92%) with previously isolated pOS-ACO1 of deepwater rice. The chromosomal location studies show that OS-ACO2 is positioned on the long arm of chromosome 9, while OS-ACO3 on the long arm of chromosome 2 of rice genome. A marked increase in the level of OS-ACO2 transcript was observed in IAA-treated etiolated rice seedlings, whereas the OS-ACO3 mRNA was greatly accumulated by ethylene treatment. Results of ethylene inhibitor studies indicated that auxin promotion of the OS-ACO2 transcription was not mediated through the action of auxin-induced ethylene. Thus, it appears that there are two groups of ACC oxidase transcripts in rice plants, either auxin-induced or ethylene-induced. The auxin-induced OS-ACO2 expression was partially inhibited by ethylene, while ethylene induction of OS-ACO3 transcription was completely blocked by auxin. These results indicate that the expression of ACC oxidase genes is regulated by complex hormonal networks in a gene specific manner in rice seedlings. Okadaic acid, a potent inhibitor of protein phosphatase, effectively suppressed the IAA induction of OS-ACO2 expression, suggesting that protein dephosphorylation plays a role in the induction of ACC oxidase by auxin. A scheme of the multiple regulatory pathways for the expression of ACC oxidase gene family by auxin, ethylene and protein phosphatase is presented.

Structure and expression of the AWI 31 gene specifically induced by wounding in Arabidopsis thaliana

Differential screening of an Arabidopsis cDNA library constructed from the plant tissues harvested 1 h after wounding resulted in the isolation of wound-inducible cDNA clones (Kim et al., 1994). The cDNA clones could be broadly classified into two groups according to the expression time of their transcripts. Nine clones from the 10 different wound-inducible cDNAs were rapidly induced, reaching a maximum level in approximately 1-1.5 h and then were progressively reduced after wounding. The cDNA clone AWI 31 showed steady accumulation of the transcripts and reached the maximum value at a later time point of 2.5 h and then started to decline. The corresponding gene of the AWI 31 in which the coding region was interrupted by an intron, had an open reading frame that predicted a protein of 386 amino acids. However, the gene product did not show any significant homology to other known proteins in the database. Northern hybridization study using the cDNA probe revealed that the gene was not regulated by other environmental stresses such as drought, high salt, low temperature, or a DPE herbicide treatment, indicating that the cDNA clone AWI 31 was specifically induced by wounding.

The semidwarf gene, sd-1, of rice (Oryza sativa L.). II. Molecular mapping and marker-assisted selection

To establish the location of the semidwarf gene, sd-1, the anthocyanin activator (A), purple node (Pn), purple auricle (Pau), and the isozyme locus, EstI-2, in relation to DNA markers on the molecular linkage map of rice, 20 RFLP markers, previously mapped to the central region of chromosome 1 (McCouch et al. 1988), were mapped onto an F2 population derived from the cross Taichung 65 (A,Pn,Pau)/Taichung 65 (sd-1). sd-1 and EstI-2 were determined to be linked most tightly to RFLP markers RG 109 and RG 220, which cosegregated with each other. The distance between these RFLP markers and sd-1 was estimated to be 0.8 cM, based on an observed recombination value of 0.8%. The order of genes and markers in this region of chromosome 1 was determined to be sd-1 - (EstI-2 - RG220 - RG109) - RG381 - A - Pn - Pau. To test the efficacy of selection for sd-1 based on these linked markers, 50-day-old F2 seedlings derived from another cross, Milyang 23/Gihobyeo, were analyzed for marker genotype. At this age, the semidwarf character could not be clearly detected based on phenotype. In addition, plant height was normally distributed in this population, making it difficult to unambiguously identify plants carrying sd-1. Thirteen seedlings homozygous for the sd-1-associated allele at EstI-2, RG220 and RG109, and 13 seedlings homozygous for the Sd-1-associated allele at all three marker loci were selected for further genetic analysis. At 20 days after heading, the culm lengths of these 26 plants were measured and the expected phenotype was confirmed in every case. These 26 plants were then selfed for four generations and F6 lines were again evaluated to determine whether any recombination among the three molecular markers, or between these markers and the sd-1 gene, could be detected. No recombinants were identified, confirming the tight linkage of these loci and the usefulness of genotypic selection for this recessive semidwarf character prior to the time when it can be evaluated based on phenotype.

The semidwarf gene, sd-1, of rice (Oryza sativa L.). I. Linkage with the esterase locus, Estl-2

The linkage relationship between the semidwarf gene (sd-1) and the isozyme locus EstI-2 was elucidated using segregating populations derived from crosses between several semidwarf testers and tall rice varieties. Bimodal distributions for culm length were observed in F2 populations of three cross combinations, including Shiokari/Shiokari (sd-1), Taichung 65 (A,Pn,Pau)/Taichung 65 (sd-1), and Milyang 23/Kasalath. Taking the valley of the distribution curves as the dividing point, two height classes were apparent with a segregation ratio of 3 tall∶1 short, demonstrating this character to be under the control of a single recessive gene. An inheritance study of esterase isozymes, based on isoelectric focusing (IEF), showed that the EstI-2 locus had two active allozymes of monomeric structure and one null form, which were designated "a", "b", and "n", respectively (Eun et al. 1990). Semidwarf testers such as Shiokari (sd-1), Taichung 65 (sd-1) and Milyang 23 have an active allozyme designated as EstI-2(aa), while the tall parents, Shiokari and Taichung 65 (A,Pn,Pau), have the active allozyme, EstI-2(bb), and Kasalath has a null form of the allozyme, EstI-2(nn). By dividing F2 populations based on EstI-2 allozyme patterns, culmlength distributions exhibited trimodal curves. Most of the short plants had the homozygous EstI-2(aa) pattern of the short parents, most of the tall plants had the homozygous pattern, EstI-2(bb) or EstI-2(nn), and most of the intermediate plants had the heterozygous EstI-2(ab) or EstI-2(an) banding pattern. Einkage analysis indicated that sd-1 and EstI-2 were tightly linked. These findings were also confirmed by segregation analyses in F3 progenies. No recombinants among 171 F3 families from the Shiokari/Shiokari (sd-1) combination, five recombinants among 267 F3 families from Taichung 65 (A,Pn,Pau)/Taichung 65(sd-1), and only two recombinants out of 237 F3 families from Milyang 23/Kasalath, were found. The recombination values were 0, 1.87 and 0.8%, respectively.