Assessment of the environmental risk of long-chain aliphatic alcohols

An environmental assessment of long-chain alcohols (LCOH) has recently been conducted under the OECD SIDS High Production Volume (HPV) Program via the Global International Council of Chemical Associations (ICCA) Aliphatic Alcohols Consortium. LCOH are used primarily as intermediates, as a precursor to alcohol-based surfactants and as alcohol per se in a wide variety of consumer product applications. Global production volume is approximately 1.58 million metric tonnes. The OECD HPV assessment covers linear to slightly branched LCOH ranging from 6 to 22 alkyl carbons (C). LCOH biodegrade exceptionally rapidly in the environment (half-lives on the order of minutes); however, due to continuous use and distribution to wastewater treatment systems, partitioning properties, biodegradation of alcohol-based surfactants, and natural alcohol sources, LCOH are universally detected in wastewater effluents. An environmental risk assessment of LCOH is presented here by focusing on the most prevalent and toxic members of the linear alcohols, specifically, from C(12-15). The assessment includes environmental monitoring data for these chain lengths in final effluents of representative wastewater treatment plants and covers all uses of alcohol (i.e., the use of alcohol as a substance and as an intermediate for the manufacturing of alcohol-based surfactants). The 90th percentile effluent discharge concentration of 1.979microg/L (C(12)-C(15)) was determined for wastewater treatment plants in 7 countries. Chronic aquatic toxicity studies with Daphnia magna demonstrated that between C(13) and C(15) LCOH solubility became a factor and that the structure-activity relationship was characterized by a toxicity maximum between C(13) and C(14). Above C(14) the LCOH was less toxic and become un-testable due to insolubility. Risk quotients based on a toxic units (TU) approach were determined for various scenarios of exposure and effects extrapolation. The global average TU ranged from 0.048 to 0.467 depending on the scenario employed suggesting a low risk to the environment. The fact that environmental exposure calculations include large fractions of naturally derived alcohol from animal, plant, and microbially mediated biotransformations further supports a conclusion of low risk.

Patellar tendon reflex as a predictor of improving motor paralysis in complete paralysis due to cervical cord injury

STUDY DESIGN

A retrospective study.

OBJECTIVE

We have encountered several cases of complete sensorimotor paralysis in which patellar tendon reflex (PTR) was demonstrated approximately 3 days after injury and improvement of motor paralysis was subsequently achieved. We considered that PTR apparent in the early stage after injury may offer an index to predict improvements in motor paralysis.

MATERIALS AND METHODS

A total of 142 patients assessed as ASIA Impairment Scale A on admission from 1979 to 1998 were included in the study. The patients who demonstrated PTR within 72 h after injury were classified as the PTR(+) group and those who did not constituted the PTR(-) group. With regard to the method of motor paralysis assessment at about 6 months after injury, patients assessed as ASIA Impairment Scale A or B (that is, complete motor paralysis) were classified as 'Non-recovered', whereas those assessed as ASIA Impairment Scale C, D or E (that is, showing obvious improvement of motor paralysis) were considered as 'Recovered'.

RESULTS

A significant difference was noted between groups, with the Recovered group including 16 of the 17 PTR(+) patients (94.1%) and 11 of the 115 PTR(-) patients (9.6%) (P<0.0001).

CONCLUSION

The results obtained indicate that motor paralysis recovery could be expected at a very high rate among patients demonstrating PTR within 72 h of injury. As all physicians should be familiar with the PTR, this seems to represent a simple and highly useful sign to predict improvements in motor paralysis during the acute stage of cervical cord injury.

Clinical application of a handy intraoperative measurement device for lumbar segmental instability

We describe the development of a new device that permits handy intraoperative measurement of lumbar segmental instability. The subjects comprised 80 patients with lumbar degenerative disease. Relationships between preoperative radiological assessments and extended distance as measured using our new device were investigated. Mean extended distance measured using the device was 3.7 +/- 1.9 mm. Correlation coefficients between angular motion and extended distance, and translational motion and extended distance were 0.76 and 0.66, respectively, revealing significant positive relationships between these values (p < 0.01 each). The correlation coefficient between the intervertebral endplate angle on the flexion film and extended distance was -0.78, showing a significant negative relationship (p < 0.01). In conclusion, the device for intraoperative measurement of lumbar segmental instability that we have developed appears to permit simple measurement of intervertebral instability and provides operators with valuable information for selecting operative methods of spinal fusion or instrumentation.

Direction of the formation of anterior lumbar vertebral osteophytes

Background

X-ray images of lumbar degenerative diseases often show not only claw osteophytes, but also pairs of osteophytes that form in a direction away from the adjacent disc. We have investigated the direction of the formation of anterior lumbar vertebral osteophytes across the lumbar vertebrae using a sufficient number of lumbar radiographs, because osteophytes images can provide essential information that will contribute to the understanding of the pathology and progress of lumbar spine degeneration.

Methods

The direction of the formation of 14,250 pairs of anterior lumbar vertebral osteophytes across the adjacent intervertebral discs in 2,850 patients who were all over 60 years old was investigated. Anterior lumbar vertebral osteophytes were distributed into six groups based on the direction of extension of each pair of osteophytes across the intervertebral disc space.

Results

In L1–L2 and L2–L3, the number of patients classified into groups B (the pair of osteophytes extended in the direction of the adjacent disc) and C (almost complete bone bridge formation by a pair of osteophytes across the intervertebral disc space) was larger than that classified into group D (the pair of osteophytes extended in a direction away from the adjacent disc). In L3–L4, L4–L5 and L5-S1, the number of patients in group D was greater than that of patients belonging to groups B and C.

Conclusion

Our study showed that pairs of osteophytes frequently formed in the direction of the adjacent disc in the upper lumbar vertebrae (L1–L2 and L2–L3) and in the direction away from the adjacent disc in middle or lower lumbar vertebrae (L3–L4, L4–L5, and L5-S1).

Changes in water content of intervertebral discs and paravertebral muscles before and after bed rest

BACKGROUND

Although low back pain can be principally produced or increased during action, it may also be induced or enhanced in the morning after bed rest. During bed rest, tissue edema (increased water content) may occur. In this study, we measured the changes in water content in the intervertebral disc and the paravertebral muscle before and after bed rest using a magnetization transfer magnetic resonance imaging (MT-MRI) technique that permits measuring water content in tissues.

METHODS

A total of 20 student volunteers were enrolled in this study. MT-MRI evaluation was performed before and after bed rest. To measure water content in the intervertebral disc and paravertebral muscle, two MRI sequences were performed using MT pulse-off and MT pulse-on. Based on the two images obtained, the equivalent cross-relaxation rate (ECR) was calculated.

RESULTS

The ECR for intervertebral discs was significantly lower after bed rest than before bed rest (P < 0.01). The ECR for paravertebral equivalent cross-relaxation rate muscles was significantly higher after bed rest than before bed rest (P < 0.05).

CONCLUSION

We obtained results indicating that after bed rest the water content in the intervertebral disc and the paravertebral muscle was increased and decreased, respectively.

Tadpole system as new lumbar spinal instrumentation

Background

There have been reports of serious complications associated with pedicle screw fixation, including nerve root injuries caused by accidental screw insertion. We have developed a new system of lumbar spinal instrumentation that we call Tadpole system^®. The purposes of this report were to show the results of a biomechanical study and the short-term outcome of a clinical study, as well as to determine the usefulness of this system.

Methods

The Tadpole system^® lumbar spinal fusion is a hook-and-rod system according to which the spine is stabilized using 2 sets of 2 spinous processes each that are held in place by 4 hooks tandemly connected to a rod. The biomechanical study was done using 5 human lumbar cadaveric spines, and the range of motion (ROM) was examined in a non-treatment model, an injured model, a pedicle screw fixation model and a Tadpole system^® model. For the short-term clinical study the Tadpole system^® was used in 31 patients, and the factors analyzed were operation time, time required for spinal instrumentation, amount of intraoperative bleeding, postoperative improvement rate of the Japanese Orthopaedic Association (JOA) score for lumbar spinal disorders, instrumentation failure, spinous process fracture, spinal fluid leakage, nerve root injury, postoperative infection, and bone fusion 2 years after the operation.

Results

The ROM in the Tadpole system^® model was slightly bigger than that in the pedicle screw fixation model, but smaller than that in the normal control model. These biomechanical data indicated that the Tadpole system^® provided fairly good stability. The mean operation time was 79 min, the mean time required for spinal instrumentation was 8 min, and the mean amount of intraoperative bleeding was 340 mL. The mean postoperative improvement rate of JOA score was 70.9 ± 24.8%. Instrumentation failure (dislocation of a hook) occurred in one patient, and none of the patients developed spinous process fracture, spinal fluid leakage, nerve root injury, or postoperative infection. Two years after the operation, bone union was confirmed in 29 of the 31 patients (93.5%).

Conclusion

We conclude that this system is a useful, easy-to-use and safe spinal instrumentation technique for lumbar fusion surgery.

Hypertrophic change of facet joint in the cervical spine

BACKGROUND

There have been few studies on degenerative changes of the cervical facet joint. This study was conducted to examine the image and clinical characteristics of patients with cervical facet hypertrophy and the significance of such characteristics.

MATERIALS AND METHODS

The subjects were 215 patients with degenerative disease of the cervical spine, and they were divided into a hypertrophic change (+) group (32 patients) and a hypertrophic change (-) group (183 patients). We defined that if the distance between the tangential line on the posterior border of the vertebral body and the tip of the superior articular process was 7 mm or over by CT, it was regarded as hypertrophic change (+). Data was analyzed using Fisher's exact test, and differences were considered significant at p<0.05.

RESULTS

The level at which hypertrophic change of the facet joint was observed was C3/4 in eight patients, C4/5 in 14, C5/6 in six, C6/7 in one, C3/4 + C4/5 in one, and C4/5 + C5/6 in two. Of the 32 patients in the hypertrophic change (+) group, 30 had an unilateral hypertrophic change. There was a significantly (p<0.05) greater proportion (28 of 32 patients, 87.5%) of males in the hypertrophic change (+) group than in the hypertrophic change (-) group, and neck pain was observed significantly more frequently in the hypertrophic change (+) group (25 of 32 patients, 78.1%).

CONCLUSION

The results showed that hypertrophic change of the facet joint occurred at mid-level of the cervical spine, usually unilaterally, was more frequent in males, and was associated with neck pain.

Mutational analysis of EGFR signaling pathway genes in lung adenocarcinomas

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Background: About fifty percent of lung adenocarcinomas harbor somatic mutations in six genes that encode signaling proteins in the EGFR signaling pathway, i.e. EGFR, HER2/ERBB2, HER4/ERBB4, PIK3CA, BRAF, and KRAS. We performed mutational profiling of a large cohort of lung adenocarcinomas to uncover other somatic mutations that could contribute to lung tumorigenesis. Methods: We analyzed genomic DNA from 261 resected, clinically well-annotated non-small cell lung cancer (NSCLC) specimens. 90% of tumors were adenocarcinomas, and 10% were squamous cell carcinomas. The coding sequences of 39 genes, encoding proteins mostly in the EGFR signaling cascade and FGFR1–4, were screened for somatic mutations via high-throughput dideoxynucleotide sequencing of PCR-amplified gene products. Mutations were considered to be somatic only if they were found in an independent tumor-derived PCR product but not in matched normal tissue. Results: First-pass analysis of 9 MB of tumor sequence identified 199 distinct types of genetic variants that differed from published reference sequences. At least one variant was found in each gene analyzed. In addition to 6 variants found in RAS genes, we further examined the 94 variants localized to exons encoding the kinase domain of respective proteins. We have thus far identified known somatic mutations in EGFR, KRAS, BRAF, and PIK3CA, in addition to a number of previously unreported single nucleotide polymorphisms (SNPs). Conclusions: Mutational profiling of genes that encode for components of the EGFR signaling pathway has revealed multiple putative genetic variants in lung adenocarcinomas. Further analysis of potential somatic mutations is in progress.

No significant financial relationships to disclose.

Physical characteristics of patients with developmental cervical spinal canal stenosis

There has been only one report on the physical characteristics of patients with developmental cervical spinal canal stenosis. The objective of this consecutive clinical study was to identify the physical characteristics of patients with developmental cervical spinal canal stenosis. The subjects were 243 patients with cervical spine disease who received treatment in our department between April 2001 and March 2002. These patients were divided into two groups (the groups of patients with and without spinal canal stenosis) on the basis of their lateral cervical spine radiographs. The six items examined were height, weight, sitting height, inter inner canthal distance, upper arm length, and head circumference in each patient, and then their values were compared between the two groups. The mean inter inner canthal distance was 2.7 cm in the group of patients with spinal canal stenosis and 3.5 cm in the group of patients without spinal canal stenosis; a significant difference (P < 0.01) was observed. Regarding height, weight, sitting height, upper arm length, and head circumference, no significant difference was found while comparing the two groups. In conclusion, developmental cervical spinal canal stenosis seems to be highly likely in patients with smaller inter inner canthal distance.

A new evaluation method for lumbar spinal instability: passive lumbar extension test

BACKGROUND AND PURPOSE

Although many studies have described clinical examination measures for the diagnosis of lumbar spinal instability, few of them have investigated the sensitivity and specificity of the measures that were used. The authors devised a passive lumbar extension (PLE) test for assessing lumbar spinal instability. The purpose of this study was to investigate the sensitivity, specificity, and positive likelihood ratio of this test.

SUBJECTS AND METHODS

The PLE test as well as the instability catch sign, painful catch sign, and apprehension sign tests were done for 122 subjects with lumbar degenerative diseases. The subjects were divided into 2 groups-instability positive and instability negative-on the basis of findings on flexion-extension films of the lumbar spine. The sensitivity, specificity, predictive values, and positive likelihood ratio of each test were investigated.

RESULTS

The sensitivity and specificity of the PLE test were 84.2% and 90.4%, respectively. These values were higher than those of other signs. The positive likelihood ratio of the PLE test was 8.84 (95% confidence interval=4.51-17.33).

DISCUSSION AND CONCLUSION

The PLE test is an effective method for examining patients for lumbar spinal instability and can be performed easily in an outpatient clinic.

Suicide during hospitalization in patients with spinal disease

STUDY DESIGN

A retrospective study.

OBJECTIVE

To examine the frequency and current status of the incidence of deaths by suicide of patients with spinal diseases during hospitalization.

SUMMARY OF BACKGROUND DATA

It was reported that most cases of deaths by suicide during hospitalization were patients admitted to the psychiatric ward. There were no reports to the incidence of death by suicide during hospitalization in patients with spinal diseases.

METHODS

Of 69,861 patients admitted to the Department of Orthopedics of 28 affiliated hospitals of our university between September 1997 and August 2002, 14,987 patients with spinal diseases were targeted for this study. We examined the number of deaths by suicide during hospitalization.

RESULTS

Of the 14,987 patients with spinal diseases, there were 5 deaths (0.03%) by suicide during hospitalization. There were no deaths by suicide in 54,874 patients with orthopedic diseases other than spinal diseases.

CONCLUSION

In the treatment of patients with spinal diseases, it seemed important for spinal surgeons to provide comprehensive treatment for the whole patient by paying attention to the relationship between a patient and a physician, in particular, by carefully observing the psychologic status of a patient.

Effects of driving on low back pain

BACKGROUND

Many previous studies have demonstrated that driving a car is a risk factor for low back pain (LBP). We have frequent contact with medical representatives who often drive cars for business, and have noticed that many of them suffer from LBP.

AIMS

To investigate how driving affected the occurrence of LBP in medical representatives.

METHODS

Questionnaire survey of all medical representatives working in Mie Prefecture (Japan).

RESULTS

A total of 551 medical representatives replied (92%). We divided the subjects into Group A (with LBP) and Group B (without LBP). There was no significant difference in mean age, height, weight or duration of continuous employment between the two groups. Mean total mileage was 342 539 km in Group A and 251 945 km in Group B (P < 0.05). There was no significant difference in estimated daily mileage or estimated daily driving time between the two groups. As for backrest inclination, most of the respondents in Group A chose 105 degrees and the majority in Group B chose 120 degrees (P < 0.001).

CONCLUSION

The total mileage was significantly higher in Group A than in Group B. We considered that the risk for LBP increased as the lumbar spine load accumulated day by day while driving a car almost every day without a holiday.

Clinical profile of long-term survivors of breast or thyroid cancer with metastatic spinal tumours

Patients with breast or thyroid cancer with metastatic spinal tumours are expected to survive relatively longer than patients with other cancers with metastatic spinal tumours. The purpose of this study was to determine the clinical characteristics of long-term survivors of breast or thyroid cancer with metastatic spinal tumours. We studied the clinical profile of long-term survivors by comparing the characteristics of nine patients who had survived for at least 5 years after a spinal operation with the characteristics of 16 patients who had not. Our results showed that the longer the time from the diagnosis of the primary cancer to the spinal operation, the longer patients with breast or thyroid cancer and metastatic spinal tumours would survive. Six of the eight patients (75.0%) who had undergone the spinal operation at least 5 years after the diagnosis of the primary cancer survived especially long. In conclusion, the duration from the diagnosis of the primary cancer to the spinal operation is very useful for predicting a prognosis in patients with breast or thyroid cancer and metastatic spinal tumours.

Development of 6-Axis Material Tester for Measuring Mechanical Spine Properties

Because mechanical spine properties having multiple degrees of freedom (DOF) are generally difficult to measure, we developed a parallel 6-axis material tester with hybrid position/force control. We give examples of 6-axis testing and results of material tests using polyurethane rubber and animal spines.

[Quality of life in patients with metastatic spinal tumors]

The authors investigated the postoperative quality of life in 89 patients with metastatic spinal tumors. As the results of our study, it was found that spinal surgery could maintain or improve the quality of life, and then most of patients with poor quality of life had multiple spine/bone metastasis or brain/spinal cord metastasis.

Prevalence of osteoarthritis, osteoporotic vertebral fractures, and spondylolisthesis among the elderly in a Japanese village

PURPOSE

To study the prevalence of osteoarthritis, osteoporotic vertebral fractures, and spondylolisthesis among elderly residents of a Japanese village and to examine the correlation between radiographic evidence of abnormality and lower back pain.

METHODS

205 men (mean age, 70.7 years) and 323 women (mean age, 70.5 years) in a Japanese village participated in this cross-sectional study. Plain lateral radiographs were taken from the lower thoracic spine to the sacral spine. They were evaluated by 3 independent orthopaedic surgeons for degree of osteoarthritis (using Weiner grading system) and the presence of osteoporotic vertebral fractures and spondylolisthesis.

RESULTS

The prevalence of osteoarthritis in elderly Japanese villagers was 38.3%, whereas that of osteoporotic vertebral fractures and spondylolisthesis was 17.8% and 8.9%, respectively. There was no significant difference in osteoarthritis between men and women, but osteoporotic vertebral fractures and spondylolisthesis were significantly more common in females (p<0.01). No significant correlation was observed between lower back pain and radiographic evidence of degenerative spinal disease.

CONCLUSION

The prevalence of spondylolisthesis in elderly Japanese was much lower than that in whites or African Americans. The prevalence of osteoarthritis or osteoporotic vertebral fractures was comparable with other English or US studies. Radiographic evidence of osteoarthritis, osteoporotic vertebral fractures, and spondylolisthesis is not necessarily associated with lower back pain.

Solution structure of the C-terminal transcriptional activator domain of FixJ from Sinorhizobium meliloti and its recognition of the fixK promoter

FixJ is a response regulator of the two-component signal transduction pathway involved in the transcriptional activation of nitrogen fixation genes of Sinorhizobium meliloti. Upon phosphorylation, FixJ transcriptionally activates the fixK and nifA promoters. We identified a FixJ recognition sequence of 16 bp in the high affinity binding site of the fixK promoter by means of a gel shift assay. In addition, the solution structure of the truncated C-terminal DNA binding domain of FixJ (FixJC) was solved by NMR spectroscopy. FixJC contains five alpha-helices that encode a typical helix-turn-helix motif as a potential DNA binding core with the highest structural similarity toward the C-terminal DNA binding domain of NarL. The addition of the DNA fragment containing the recognition sequence of the high affinity FixJ binding site resulted in intermediate to slow exchange interactions on the NMR time scale in the spectrum of FixJC, while the exchange was rapid in the case of control DNA. These spectral data suggest that more than one molecule of FixJC binds to the recognition sequence, although FixJC alone is present in monomeric form in solution. This result is consistent with a scenario in which a transcriptionally active species of FixJ is a homodimer of the phosphorylated form.

Pre-and postoperative psychological characteristics in mothers of patients with idiopathic scoliosis

The purpose of the present study was to clarify changes in the psychological state of mothers of patients with idiopathic scoliosis, and to clarify relationships between the psychological states of the mothers and patients. The Maudsley personality inventory (MPI) was administered to 30 patients with idiopathic scoliosis who underwent surgery and their mothers preoperatively and at about 1 year postoperatively. We investigated the relationships between preoperative MPI scores and postoperative scores in patients and their mothers, respectively, and the relationships between MPI scores for patients and mothers. The results of the present study revealed that patients became more extroverted following surgery, while mothers displayed reduced neurotic tendencies. In conclusion, the mothers of patients who undergo corrective treatment for scoliosis may have experienced a substantial psychological burden before surgery, and doctors who treat patients with scoliosis should bear this point in mind.

Assessment of gait and balance in patients with spinal diseases using the leg reposition test

We devised a new leg reposition test, to assess gait and balance in patients with spinal diseases. This study included 344 patients who were scheduled to undergo spine surgery; 14 (4.1%) patients showed positive results. These 14 patients had worse gait status than leg reposition test-negative patients both preoperatively and postoperatively. The leg reposition test is a simple procedure, and requires no specialized equipment. This study showed that the leg reposition test has a strong relation with gait status, and therefore a high clinical significance regarding the assessment of preoperative gait and balance and prediction of postoperative gait status.

A case of idiopathic spinal cord herniation with duplicated dura mater

The patient was a 48-year-old man in whom a slow progression in walking difficulty occurred over a year. Magnetic resonance imaging (MRI) and computed tomography myelography (CTM) revealed duplicated dura mater from T1 to T12 and spinal cord herniation in the inner layer of the dura at the T4-T5 level. Idiopathic spinal cord herniation with duplicated dura mater was diagnosed, and surgery was performed. Intraoperative findings were of an elliptical defect of about 1 cm in the inner layer of the dura at the T4-T5 level, into which the spinal cord was herniated. A 1.5-cm cephalocaudal incision was created in the inner layer of the dura, and the incarcerated spinal cord was released, resulting in resolution of gait disturbance and an excellent postoperative clinical course. We reviewed the reports of 11 cases of idiopathic spinal cord herniation with duplicated dura mater and summarized the clinical and imaging characteristics as follows: 1) A hernial orifice was found at the T4-T6 level, 2) cross-sectional MRI or CTM showed a "snowman-like" deformation of the spinal cord, and 3) symptoms were often improved by widening the hernia orifice.

Phosphoglyceride crystal deposition disease in the spine: a case report

The authors report phosphoglyceride crystal deposition disease in the spine after a lumbar anesthetic given at the time of appendectomy. A 76-year-old Japanese woman with increasing lumbar pain was transported to our hospital in an ambulance. She had tumor-like lesions that had repeatedly appeared in injured soft tissues for >20 years. Osteolytic changes were detected by x-ray in the 12th thoracic vertebra and the 4th lumbar vertebra. Compression of the left L4 nerve root was detected by myelography, and a tumor corresponding to the left L3-L4 intervertebral foramen was determined by computed tomography. An operation to achieve posterior decompression and fusion was performed. The histopathologic tests on this coarse matter revealed a radial deposition of needle crystals and a strong foreign matter reaction in the periphery. Based on the above analyses, the deposited crystals were regarded as phosphoglyceride. Phosphoglyceride crystal deposition disease is characterized by the deposition of crystals of the phospholipid called phosphoglyceride in sites especially susceptible to invasion, such as surgical sites. To our best knowledge, only three cases of phosphoglyceride crystal deposition disease, including this one, have been reported.

Outcome of late surgical treatment in patients with incomplete paraplegia due to spinal degenerative diseases

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

To assess the outcome of late surgical intervention in patients with incomplete paraplegia due to spinal degenerative diseases.

SETTING

Three men and four women with cervical or thoracic spinal degenerative diseases, who preoperatively were unable to walk for more than 6 months in Mie prefecture, Japan.

METHODS

Review of clinical records and questionnaire survey regarding the walking ability of patients 2 years after surgery.

RESULTS

All seven patients were unable to walk postoperatively.

CONCLUSION

A late surgical intervention may not lead to functional recovery in patients with spinal degenerative disease who were unable to walk for at least 6 months.

Inheritance of early elongation ability in floating rice revealed by diallel and QTL analyses

In floating rice, stem elongation begins much earlier than in non-floating rice, which is the major survival mechanism for flooding. Inheritance of this early elongation ability was studied using diallel and quantitative trait locus (QTL) analyses. The diallel analysis was undertaken using a set of 6x6 half-diallel crosses involving four floating ("Goai", "Habiganj Aman VIII", "Badal 106", and Oryza rufipogon strain W120) and two non-floating ("Latisail" and "Patnai 23") parents. The additive gene effects were higher than the dominant effects. The dominant alleles were concentrated in the cultivated floating parents (("Goai", "Habiganj Aman VIII", "Badal 106"), whereas the recessive alleles were in the wild floating parent (W120). A QTL analysis using a "Patnai 23" x "Goai" F(2) population detected two putative QTLs. Of these QTLs, the one on chromosome 12 behaved as a partially dominant major gene that explained more than half of the total genetic variation.