Biomedical subjects

I H Chen

Publications and source records attributed to I H Chen.

At least 37 records · Page 2Linked to original sources

PubMed1999

Routine donor leg angiography before vascularized free fibula transplantation is not necessary: a prospective study in 120 clinical cases.

To evaluate the value of routine preoperative angiographies of donor sites, 120 patients with free fibula osteoseptocutaneous flap transplantations were included in this prospective study, which consisted of preoperative evaluation of dorsalis pedis and tibial posterior artery pulsation and angiographies of the donor legs (120 patients) and contralateral legs (111 patients). Both pedal pulses were palpable in 114 patients, and only one pulse was palpable in six patients. The respective nonpalpable foot pulses were detectable with pencil Doppler in five patients, but they were not detectable in one patient. Intraoperatively, the latter patient had a relatively hypertrophied peroneal artery as compared with both the tibial posterior and tibial anterior arteries. The angiographic result was arteria peronea magna. The other five patients showed intraoperatively and angiographically normal-sized major arteries of the lower leg. In three patients with normal pedal pulses, hypoplasias of either the tibial anterior or tibial posterior arteries were found intraoperatively. These findings corresponded with the angiographical results. In all patients (n = 119), except one with peroneal artery hemangioma, free osteoseptocutaneous fibula flap was harvested from the originally planned leg without subsequent sequelae to the respective donor leg. In 231 leg angiographies, only 7 cases (3 percent) with abnormalsized major lower leg arteries were described. The diagnoses in these cases were hypoplasia of either the tibial posterior or tibial anterior artery (4 cases), arteria peronea magna (2 cases, one of which was a false positive), absence of peroneal artery combined with hypoplastic tibial posterior artery (1 case), and hemangioma of the peroneal artery (1 case). From this prospective study, it was determined that routine preoperative angiography of the donor leg before fibula transplantation is not justified. It does not add relevant new information about donor leg vascularity, provided that the clinical evaluation of the pedal pulses is well conducted. The only two conditions that may require a preoperative donor leg angiography are abnormal pedal pulses or significant previous lower leg trauma.

Adolescent↗

PubMed1999

Donor site morbidity after suprafascial elevation of the radial forearm flap: a prospective study in 95 consecutive cases.

From March of 1995 to November of 1997, 95 free radial forearm flaps for orofacial reconstructions were performed and included in this prospective study of donor site morbidity. All flaps were elevated using the suprafascial dissection technique. Donor site closure was performed with either split-thickness skin grafts (64 cases) or full-thickness skin grafts (31 cases). Among the 95 flaps, there were two complete flap losses and one partial flap loss because of arterial thrombosis. One orocutaneus fistula was successfully treated with a pedicled pectoralis major flap. At the donor site, the rate of complete take of skin graft was 94 percent in 95 patients. Functional and aesthetic results evaluated at least 6 months postoperatively in 50 patients revealed no significant change in grip power, pulp-to-pulp pinch power, or wrist movement in the complete skin graft take group (45 cases), whereas in the partial skin graft failure group (5 cases), both grip power and movement were significantly decreased. There was no remarkable cold intolerance in any of the 50 patients. Critical evaluations of sensory change revealed numbness distal to the donor site in 54 percent of the patients. However, dysesthesia was usually mild and improved spontaneously as time passed. Aesthetic outcome was rated as good or fair in 98 percent of the cases. The results of this prospective study show that suprafascial elevation of the radial forearm flap is superior to the classic elevation technique, particularly with regard to a higher rate of immediate complete take of skin grafts, thus avoiding impairment of range of motion and strength of the donor hand.

Adult↗

PubMed1999

Sensation recovery on innervated radial forearm flap for hemiglossectomy reconstruction by using different recipient nerves.

The objectives of this study were (1) to determine the extent of sensory recovery on hemitongues reconstructed with innervated radial forearm flaps and (2) to assess the influence of various clinical and surgical factors over the return of sensation, including the use of different recipient nerves for neurorrhaphy. Twenty-eight patients with tongue cancer who underwent hemiglossectomy and primary reconstruction with innervated radial forearm flaps over a 3-year period were studied. Mean postoperative follow-up was 18.2 months (range 6 to 32 months). Sensory recovery was assessed in a blind manner by two examiners that used (1) static two-point discrimination, (2) light touch sensation, (3) pain perception, and (4) hot and cold temperature perception. Different surfaces were assessed with each method on the reconstructed hemitongue and on the intact contralateral hemitongue (used as control). The following factors and their relationship with flap sensory recovery were analyzed: age, smoking history, size of the reconstructed defect, administration of postoperative radiation therapy, recipient nerve, and neurorrhaphy technique. Comparative statistical analysis (p < 0.05) between both hemitongues was performed using paired t test followed by Bonferroni correction for static two-point discrimination and light touch sensation. Fisher exact test analysis was used for pinprick and hot and cold temperature perception. The control side was ignored in analyzing the effects of the risk factors. The tip, dorsal aspect, ventral surface, and floor of mouth on the reconstructed hemitongue had comparable static two-point discrimination when compared with the intact hemitongue. Light touch sensation was also similar in the tip and dorsal aspect of both hemitongues; however, a statistically significant difference (p < 0.05) was observed on the ventral surface and floor of mouth of the reconstructed hemitongues. Likewise, pain perception was significantly decreased in the floor of the mouth, compared with other surfaces. No clearly dependent association was established between return of flap sensation and age, tobacco use, and size of the reconstructed defect. Light touch sensation, pain, and temperature perception were significantly decreased when the patients had received postoperative radiation therapy. In addition, all four sensory tests were significantly diminished (p < 0.05) when the recipient nerve used for neurorrhaphy was a nerve other than the lingual or the inferior alveolar nerve, and also when an end-to-side nerve repair was used. Sensation recovery of the innervated radial forearm flap after hemitongue reconstruction approaches normal compared with the contralateral intact hemitongue. Lower return of sensation may be anticipated in patients who receive postoperative radiotherapy. Good recovery of sensation is predictable when either the lingual or inferior alveolar nerve is used for neurorrhaphy, in contrast to using other recipient nerves.

Adult↗

PubMed1999

Microsurgical reconstruction in recurrent oral cancer: use of a second free flap in the same patient.

Primary microsurgical reconstruction is the treatment of choice for ablative defects of oral carcinoma. As a result of this trend, more and more patients with recurrent oral carcinoma who have been initially treated with surgical excision and reconstructed with free flaps are being seen. However, a second microsurgical reconstruction attempt in these cases raises questions about the flap choices, availability of recipient vessels, and effects of previous treatment modalities. Herein, 35 patients with perioral carcinoma who had two successive tumor resections and reconstruction with free flaps on each occasion are presented. A total of 75 free tissue transfers were carried out for the first and second reconstructions. After the first tumor resection, 28 radial forearm fasciocutaneous flaps, 7 fibula osteoseptocutaneous flaps, 1 iliac osteomyocutaneous flap, and 2 rectus abdominis myocutaneous flaps were used. For reconstruction after the recurrence, 17 radial forearm fasciocutaneous flaps, 13 fibula osteoseptocutaneous flaps, 3 rectus abdominis myocutaneous flaps, 2 anterolateral thigh flaps, 1 jejunum flap, and 1 tensor fasciae latae flap were used. More vascularized bone transfers were performed during the second reconstruction since the excision for the recurrence frequently required segmental mandibulectomy. The complete flap survival rate was 97.3 percent and 94.6 percent with a reexploration rate of 7.9 percent and 13.5 percent for the first and second free tissue transfers, respectively. The mean follow-up time throughout the procedures was 37.5 months. Disease-free interval between reconstructions was 20.8 months. At the time of evaluation, 54.3 percent of the patients were surviving an average of 19 months since the second reconstruction. The results suggest that free flaps represent an important option in reconstruction of recurrent perioral carcinoma cases undergoing reexcision. When used in this indication they are as safe and effective as the initial procedure.

Adult↗

PubMed1999

Free fibula osteoseptocutaneous-pedicled pectoralis major myocutaneous flap combination in reconstruction of extensive composite mandibular defects.

Lateral composite mandibular defects resulting from excision of advanced oral carcinoma often require mandible, intra-oral lining, external face, and soft-tissue bulk reconstruction. Ignorance of importance soft-tissue deficit in those patients may cause significant morbidity and functional loss. Such defects, therefore, can be reconstructed best with a double free flap technique. However, this procedure may not be feasible for every patient or surgeon. An alternative procedure is a free fibula osteoseptocutaneous flap combined with a pedicled pectoralis major myocutaneous flap. This combination was used in reconstruction of extensive composite mandibular defects in 14 patients with T3/T4 oral squamous cell carcinoma. All patients were men, and the average age was 54.3 years. The septocutaneous paddle of the fibula flap was used for the mucosal lining of the defects while the bony part established the rigid mandibular continuity. The pectoralis major flap then covered the external skin defect in the face and cheek, and the dead spaces left by the extirpated masticator muscles, buccal fat, and parotid gland. One free fibula flap failed totally, and one pectoralis major flap developed marginal necrosis. At the time of final evaluation, nine patients (64.3 percent) were alive, surviving an average of 25.7 months. All patients eventually regained their oral continence and an acceptable cosmetic appearance. In conclusion, the fibula osteoseptocutaneous flap plus regional myocutaneous flap choice is a successful and technically less demanding alternative to the double free flap procedures in reconstruction of extensive lateral mandibular defects.

Adult↗

PubMed1999

Management of secondary soft-tissue deficits following microsurgical head and neck reconstruction by means of another free flap.

Secondary soft-tissue deficits may develop following a microsurgical reconstruction in the head and neck region because of inadequate planning or chronic effects of radiotherapy. Although most cases could be managed with alternative methods, free flaps might be necessary in difficult cases. Herein are described 11 cases of microsurgical head and neck reconstruction in which secondary soft-tissue deficits required transfer of another soft-tissue free flap. All patients had malignant tumors treated with surgical resection, and their defects were reconstructed with free flaps. Seven patients received either preoperative or postoperative adjunctive radiotherapy. These patients gradually developed signs and symptoms of soft-tissue deficiency in the reconstructed area, and a soft-tissue free flap transfer was required for treatment within an average of 21.5 months of their initial reconstruction. Five rectus abdominis, one rectus femoris, one latissimus dorsi, one tensor fasciae latae myocutaneous, one radial forearm, one medial arm, and one dorsalis pedis flap were used for this purpose. All flaps survived completely. The average follow-up time was 32 months. Significant improvement was achieved in all cases, and no further major surgical procedures were required. Secondary soft-tissue deficits that could not be predicted or prevented during the initial microsurgical reconstruction may be treated successfully by a subsequent free soft-tissue transfer in selected cases.

Adult↗

PubMed1999

Anesthesia for ankylosing spondylitis patients undergoing transpedicle vertebrectomy.

BACKGROUND: Ankylosing Spondylitis (AS) patients present specific challenges to the anesthesiologists. Airway management, central venous access, positioning, neuraxial monitoring and protection as well as management of massive blood loss may prove to be difficult. We retrospectively reviewed the anesthetic management of consecutive AS patients who underwent transpedicle vertebrectomy (TPV). METHODS: To secure airway and administer anesthesia, we used awake fiberoptic endotracheal intubation. The central venous access was attempted through the infraclavicular approach. The positioning was made possible with modification of the operation table and padding. The neuraxial monitoring was done with both somatosensory evoked potentials (SSEPs) and the modified transcranial magnetic evoked potential (tcMMEP). The spinal cord protection was attempted with deliberate hypothermia. To prevent massive blood loss we did controlled hypotension, and autotransfusion. RESULTS: Fiberoptic endotracheal intubation was done smoothly in all cases except two. In one of these two cases, endotracheal intubation was successful only after cricothyroidectomy and retrograde intubation. In the other case antegrade stiff catheter guided intubation was attempted to overcome the acute angulation cause by fixed cervical flexion. Central venous access through infraclavicular approach was agreeable except one case of pneumothorax. Massive rapid blood loss during vertebral osteotomy, occurred in one patient with fall of the mean blood pressure to 20 mmHg and ventricular tachycardia for 10 min, during which all the SSEPs and tcMMEP activities disappeared. The patient recovered without sequelae. CONCLUSIONS: Although it is extremely challenging, with proper planning, anticipation of difficulties and meticulous work in airway management, central venous catheterization and positioning as well as prevention of neurological injury and massive bleeding, we successfully accomplished fine job of anesthesia for the AS patients presented for correction of severe kyphosis.

Adult↗

PubMed1998

Reliability of the venae comitantes in venous drainage of the free radial forearm flaps.

The radial venae comitantes are usually considered as an accessory venous outflow tract in the free radial forearm flap because of their smaller size and thinner structure when compared with those of the cephalic vein. To evaluate the reliability of the deep venous system, a single radial vena comitans anastomosis was performed to serve as the sole venous outflow tract in 94 consecutive radial forearm free flap transfers. The suprafascial dissection technique was used in flap elevation, which allowed preservation of the cephalic vein and the dorsal branch of the radial nerve. In all cases, the external diameter of at least one vena comitans was adequate (< or = 1.5 mm) to perform a smooth microvascular anastomosis; in none of the cases was a venous anastomosis failure detected. Preselected use of a single vena comitans for the venous drainage of radial forearm free flaps was proven to be reliable and was preferred because of the ease of flap dissection and better donor site appearance.

Adult↗

PubMed1998

Increased C-type natriuretic peptide mRNA expression in the kidney of diabetic rats.

To investigate the responsiveness of renal-synthesized C-type natriuretic peptide (CNP) to changes in water and electrolyte balance, we measured renal CNP mRNA levels, plasma CNP concentrations and urinary CNP excretion rates in streptozotocin-induced diabetic rats eating a normal (0.26% NaCl) or low (0.04% NaCl) salt diet. Using reverse transcription-PCR followed by Southern blot analysis, we found that renal cortical and medullary CNP mRNA levels were markedly enhanced in diabetic rats from the 14th day and remained enhanced with an accompanying elevation of urinary CNP excretion rates for the entire 60-day study period. All increases of renal CNP mRNA and urinary CNP excretion rates in diabetic rats were attenuated in low salt diet-treated diabetic rats as well as insulin-treated diabetic rats. These results demonstrate that renal CNP synthesis is enhanced in diabetic rats and the increase of renal CNP mRNA is ameliorated by salt restriction and insulin treatment. These results imply that renal-synthesized CNP is responsive to the alteration of water and electrolyte homeostasis in diabetic rats.

Animals↗

PubMed1998

Modified transcranial electromagnetic motor evoked potential obtained with train-of-four monitor for scoliosis surgery.

BACKGROUND: To monitor the spinal cord with somatosensory evoked potential (SSEP) is an accepted adjunct in the surgical correction of spinal deformities, but it does not directly assess the motor function. The use of motor evoked potential (MEP) has thus been introduced in an effort to meet this important need. METHODS: This preliminary report concerned 30 cases of scoliosis who underwent surgical correction under the surveillance of modified transcranial electromagnetic motor evoked potential (tcMMEP). Train-of four (TOF) stimulator output was connected to an electromagnetic stimulator. The rate of repetition and interval of stimulation were controlled by TOF stimulator. Electromyographic (EMG) signals were obtained from the abductor hallucis muscle of both feet and interpreted as MEP activity. Anesthesia was made possible by propofol as a basic agent and isoflurane as supplement. Analgesia was obtained with sufentanil and fentanyl and amnesia enhanced by midazolam. Atracurium mixed with vecuronium in a ratio of 4:1 by weight in possible lowest dose was given to provide adequate muscle relaxation yet without the molestation of rapid reversal upon the request of wake-up test by the surgeon. Deliberate hypothermia and controlled hypotension were also applied since they did not interfere with the tcMMEP signals. RESULTS: Although no attempt was made to control the level of muscle relaxation at T1 more than 30%, tcMMEP signals could be obtainable during induction, at the time of surgical correction and at the end of the operation. TcMMEP onset latency was 27.32 +/- 0.45 msec on the left side and 27.27 +/- 0.54 msec on the right side. The amplitude was 3.52 +/- 1.97 mV on the left side and 4.05 +/- 1.22 mV on the right side. CONCLUSIONS: The modified tcMMEP is so stable and convincing that research for similar modification is now undergoing with the other brand of TOF monitor by our team.

Adolescent↗

PubMed1997

CYP2E1 genetic polymorphisms and risk of nasopharyngeal carcinoma in Taiwan.

BACKGROUND: Nasopharyngeal carcinoma occurs disproportionately among individuals of Chinese descent. The cytochrome P450 2E1 enzyme (CYP2E1) is known to activate nitrosamines and other carcinogens that are possibly involved in the development of this disease. Certain alleles of the CYP2E1 gene are thought to be more highly expressed than others, and their distribution varies between Asian and Caucasian populations. We conducted a case-control study to investigate whether such variations affect the risk of developing nasopharyngeal cancer. METHODS: Three hundred sixty-four patients with nasopharyngeal carcinoma (96% of 378 eligible patients) and 320 control subjects (86% of 374 eligible subjects) were studied. A risk factor questionnaire was administered to participants to assess factors postulated to be linked to nasopharyngeal carcinoma. Peripheral blood was obtained from all subjects and DNA was purified from nucleated cells. A polymerase chain reaction-based restriction fragment length polymorphism assay that used the restriction enzymes Rsa I and Dra I was used to detect wild-type and variant forms of the CYP2E1 gene. RESULTS: Individuals homozygous for an allele of the CYP2E1 gene that is detected by Rsa I digestion (c2 allele) were found to have an increased risk of nasopharyngeal carcinoma (relative risk [RR] = 2.6; 95% confidence interval [CI] = 1.2-5.7); this effect was limited to nonsmokers (RR = 9.3; 95% CI = 2.7-32) and was not affected by alcohol consumption. CONCLUSIONS: Our findings suggest that the CYP2E1 genotype is a determinant of nasopharyngeal carcinoma risk.

Adult↗

PubMed1997

Primary cervical neuroblastoma in infants.

Although neuroblastoma is a relatively common malignancy of childhood, it is rarely of cervical origin. We encountered two cases of primary cervical neuroblastoma in infants. The first case was in a newborn who presented with noisy breathing, dyspnea, and choking on feeding soon after birth. Physical examination disclosed a left retropharyngeal mass near the midline causing aerodigestive compromise. Magnetic resonance imaging showed a well-defined hyperintense mass in the corresponding region. The infant underwent complete surgical excision of the mass 1 month after birth. The pathology report confirmed neuroblastoma. Horner's syndrome developed soon after surgery but resolved spontaneously within 6 months. No recurrence was noted during a 3-year follow-up period. The second patient, a 5-month-old female, presented with stridor and shortness of breath of 2-weeks' duration due to a right cervical mass. Magnetic resonance imaging showed a parapharyngeal mass suggestive of neuroblastoma. Complete surgical excision was done at the expense of sacrificing the sympathetic nerve trunk. The pathologic diagnosis was moderately differentiated neuroblastoma. No recurrence was noted when the patient was seen 2 years after surgery, although right-sided Horner's syndrome persisted. Surgical intervention can result in a good prognosis for low stage cervical neuroblastomas; however, long-term follow-up is important.

Female↗

PubMed1996

Biomechanical evaluation of subcortical versus bicortical screw purchase in anterior cervical plating.

The purpose of this in vitro study is to compare the stabilities provided by anterior cervical H-plating with screws purchased either subcortically or bicortically on porcine cervical spines. Nine porcine cervical spines (C3-C4) were challenged by 12 Nm in extension followed by 6 Nm in flexion in 6 consecutive steps, i.e., (1) when disc was intact, (2) after discectomy. Subsequently, a tricortical bone graft was inserted to simulate interbody fusion. Each specimen was tested again (3) when plated with 16 mm screws to purchase subcortically and (4) after cyclic loading (f = 0.5 Hz, n = 1000), (5) when plated with 30 mm screws to purchase bicortically and (6) after cyclic loading. Neutral zone and range of motion were parameters normalized for comparison. The results showed comparable stability in constructs plated with screws purchased either subcortically or bicortically before cyclic loading. Cyclic loading deteriorated construct-bone relation in both groups, yet bicortically purchased screws rendered additional stability in anterior cervical plating.

Animals↗

PubMed1996

Atlantoaxial arthrodesis using Halifax interlaminar clamps reinforced by halo vest immobilization: a long-term follow-up experience.

Thirty-two patients who underwent atlantoaxial arthrodesis using Halifax interlaminar clamps and halo vests between January 1989 and December 1992 were reviewed. The atlantoaxial instabilities were related to trauma in 16 patients, including 14 patients with unstable odontoid fractures, 1 patient with a complex C2 fracture, and 1 patient with a disrupted transverse ligament. Of the other 16 patients, whose atlantoaxial instabilities were nontraumatic in origin, 9 had instabilities that were secondary to rheumatoid arthritis, 1 had instability that was secondary to tuberculous infection, and 6 had instabilities that were caused by os odontoideum. The patients were followed postoperatively with lateral cervical radiographs for an average of 37 months (range, 16-59 mo). Solid atlantoaxial arthrodeses were achieved in all (100%) of these 32 patients after 32 to 111 days (average, 84.5 d) of halo immobilization, indicating atlantoaxial arthrodeses can be reasonably anticipated when Halifax interlaminar clamps with autogenous iliac bone grafting are reinforced by halo vest immobilization for 3 months.

Adolescent↗

PubMed1996

[Pulmonary and paradoxical embolism after total knee replacement--a case report].

Pneumatic tourniquet and hone cement are often applied in orthopaedic surgery. In lower limb surgery, deep vein thrombosis may occur after release of tourniquet, causing embolism of lungs and vital organs. Paradoxical embolism may develop if the patients present extracardiac or intracardiac right to left shunt, such as atrial septum defect, etc. A 60-year-old female patient suffered from osteoarthritis of both knees was admitted for total knee replacement (TKR). Pneumatic tourniquet was inflated on the operated leg for the orthopaedic surgery which lasted for 2h. Dyspnea, sinus tachycardia and abdominal pain were noted after TKR. Blood gases analysis showed arterial hypoxemia and respiratory alkalosis. Chest X-ray revealed diffused bilateral pulmonary infiltration, pulmonary trunk engorgement, and decreased lung markings. Two days after TKR under the impression of peritonitis, she received exploratory laparotomy in which ischemic bowel and gall bladder were found. Pulmonary and paradoxical embolism were diagnosed, both of which were the well-known complications of TKR with tourniquet and bone cement application. The patient finally succumbed because of multiple organ failures.

Embolism, Paradoxical↗

PubMed1995

Variance in the measurement of sagittal lumbar spine range of motion among examiners, subjects, and instruments.

STUDY DESIGN: Repeated measurements were made of lumbar sagittal range of motion by 14 examiners using three different measurement instruments. OBJECTIVES: To determine the reliability of lumbar range of motion measurements among examiners, subjects, and instruments, and to determine whether variance is due to subject inconsistency, examiner inconsistency, differences between examiners, or differences between instruments. SUMMARY OF BACKGROUND DATA: Measurements of lumbar spine range of motion are widely used in research and clinical applications as well as in disability rating systems for patients with low back pain. METHODS: Fourteen examiners measured the sagittal range of motion. Using three instruments, 18 healthy subjects were measured twice in a randomized sequence with blinded readings when performing full flexion, and partial flexion to a defined midpoint. None of the examiners routinely used the particular instruments in their practices. RESULTS: The mean test-retest reliability was 4.9 degrees. The intraexaminer reliability did not differ significantly among the examiners. Furthermore, there was no systematic difference resulting from instruments or posture condition. However, there was a statistically significant variance among examiners--i.e., a poor interexaminer reliability. CONCLUSION: The most likely explanation for these findings is the variability among examiners in locating bony landmarks. The results indicate that range of motion measurements must be interpreted with caution in clinical, research, and disability applications. Test administrator training may improve results, but this could not be determined from this study.

Adolescent↗

PubMed1995

The effects of lateral trunk bending on muscle recruitments when resisting nonsagittally symmetric bending moments.

STUDY DESIGN: Surface electromyographic activities were measured in 15 subjects as they maintained a static laterally bent trunk posture and resisted sagittally symmetric and asymmetric moments applied to their torsos. The moment magnitudes were 20 and 40 Nm and had transverse plane directional components in 30 degrees increments surrounding the subjects' torsos. OBJECTIVES: To quantify the myoelectric responses from eight trunk muscles as asymmetric loads were applied to the laterally bent torso. SUMMARY OF BACKGROUND DATA: Asymmetric material handling frequently results in lateral bending of the torso. Each of these factors have been linked via epidemiologic investigations to the incidence of low back disorders. Little information is available that describes the response of the trunk muscles when the trunk is bent to the side. METHODS: Subjects stood in a reference frame and adjusted their trunk posture to marks on a video display that indicated when a 20 degrees lateral bend to the right had been achieved. Moments were applied to the torso by connecting weights via cables and pulleys to a chest harness. Electromyographic activities were recorded bilaterally from the erector spinae, latissimus dorsi rectus abdominis, and external oblique muscles. RESULTS: The electromyographic data indicated that the muscles showed the greatest activity when they were in opposition to the applied sagittal and frontal plane moments. The left external oblique showed the greatest response and was sensitive to the widest range of moment direction conditions. All of the muscles, except for the left latissimus dorsi, at times contributed antagonistic moments in the sagittal plane or the frontal plane, or in both planes. These data were compared with previously obtained data from an upright neutral posture. CONCLUSIONS: Statistical analyses indicated that the responses of both external obliques and the left erector spinae to the moment direction conditions were significantly different between the laterally bent and neutral postures.

Abdominal Muscles↗

PubMed1995

Overlapping initiator and TATA box functions in the basal core promoter of hepatitis B virus.

The regulation of transcription of the hepatitis B virus core promoter is an important event in the viral life cycle. Two messages, precore and pregenomic RNAs, that are initiated 30 nucleotides apart are produced by the core promoter. Precore RNA encodes nucleocapsid protein and pregenomic RNA core and polymerase. The latter transcript also serves as a template for viral genome replication via reverse transcription. We have previously defined a basal core promoter, which contains four TA-rich sequences (TA1 through TA4) but no canonical TATA element, that can direct transcription of both messages. In this study, we demonstrated that a stretch of 15 nucleotides containing TA4 is sufficient to direct precise initiation of both precore and pregenomic transcripts. This sequence can function as both an initiator and a TATA element. Mutational analysis further revealed that sequences essential for either function are colocalized. The significance of this finding with respect to the basal transcription mechanism and regulation of viral gene expression is discussed.

Base Sequence↗