Biomedical subjects

S L Howng

Publications and source records attributed to S L Howng.

At least 19 recordsLinked to original sources

PubMed2006

The effect of an adenosine A1 receptor agonist in the treatment of experimental subarachnoid hemorrhage-induced cerebrovasospasm.

BACKGROUND: Adenosine is a potent vasodilator and an important modulator of cardiovascular function. It has been postulated that nitric oxide (NO) is involved in adenosine-induced vasodilation. This study was designed to examine the effect of an adenosine A1 agonist, N6-cyclopentyladenosine (CPA), in the prevention of subarachnoid haemorrhage (SAH)-induced vasospasm. Method. Experimental SAH was induced in Sprague-Dawley rats by injecting 0.3 mL autogenous blood into the cisterna magna. Intraperitoneal injections of CPA (0.003 mg/kg), or vehicle were administered 5 min and 24 hours after induction of SAH. The degree of vasospasm was determined by averaging the cross sectional areas of the basilar artery 2 days after SAH. Expressions of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in basilar artery were evaluated. Findings. There were no significant differences among the control and treated groups in physiological parameters recorded before sacrifice. When compared with animals in the control group, cross-sectional area of basilar arteries areas in the SAH only, SAH plus vehicle and SAH plus CPA groups were reduced by 19% (p < 0.01), 22% (p < 0.01), and 9% (p = 0.133), respectively. The cross-sectional areas of the CPA-treated group differed significantly from those of the SAH only and SAH plus vehicle group (p < 0.05). Induction of iNOS-mRNA and protein in basilar artery by SAH was not significantly diminished by CPA. The SAH-induced suppression of eNOS-mRNA and protein were relieved by CPA treatment. Conclusions. This is the first evidence to show an adenosine A1 receptor agonist is effective in partially preventing SAH-induced vasospasm without significant cardiovascular complications. The mechanisms of adenosine A1 receptor agonists in attenuating SAH-induced vasospasm may be, in part, related to preserve the normal eNOS expression after SAH. Inability in reversing the increased iNOS expression after SAH may lead to the incomplete anti-spastic effect of CPA.

Adenosine↗

PubMed2005

Fracture of anterior cervical plate implant--report of two cases.

Anterior cervical plate is a convenient and popular implant employed after corpectomy and bone grafting for traumatic or degenerative cervical spine disease. Although short-segment anterior cervical surgery may adequately be managed with anterior plate fixation alone, multilevel anterior cervical constructs exhibit a relatively high complication rate warranting a simultaneous posterior fusion. We report two patients undergoing two-level anterior corpectomy/fusion with a fixed anterior plate alone and exhibiting plate fracture in conjunction with pseudoarthrosis. The instrument failure was mainly attributed to pseudoarthrosis. However, improper contouring of the plate causing microstructural damage might create a weak point and contributed to this unusual hardware failure.

Bone Plates↗

PubMed2005

Simultaneous multiple hypertensive intracerebral haemorrhages.

BACKGROUND: Simultaneous occurrence of multiple intracerebral haemorrhages (ICHs) in different arterial territories is a rare clinical event which has been reported to be associated with cerebral amyloid angiopathy, venous sinus thrombosis, coagulopathy, vasculitis, haemorrhagic transformation of cerebral infarcts and multiple intracranial pathologies such as vascular anomalies or tumours. Although hypertension is the most common etiological factor for the development of spontaneous single intracerebral bleeding, its role in simultaneous multiple ICHs is not clear. METHODS: The authors have reviewed all patients with non-traumatic ICH admitted to Kaohsiung Medical University Hospital from 1993 to 2002. Ten hypertensive patients with simultaneous multiple ICHs were found. For the purpose of comparison, another 600 cases with solitary hypertensive ICH were also reviewed as a control group. Computerized tomographic scans and medical records concerning patients' histories, clinical presentations, locations of haematomas, associated risk factors, and outcome were analyzed. FINDINGS: The mean age and sex distribution were similar in both patient groups. Bilateral putaminal or thalamic haemorrhages were the most common combinations of simultaneous bleedings. As for the individual location of haematoma, there was a strong preponderance for the supratentorial space with the thalamus being the most preferable site. The duration of hypertension was longer and the percentage of previous stroke was higher in patients with multiple ICHs. Other associated risk factors were similar in both groups except for higher incidence of hypercholesterolemia in multiple ICHs group. Patients with simultaneous multiple ICHs had a much worse outcome compared to those with solitary ICH. CONCLUSIONS: As with solitary ICH, hypertension is still the most important etiological factor for simultaneous multiple ICHs. The widespread and prolonged degeneration of intracerebral arterioles predispose patients to the development of multiple ICHs, which could be justified by the longer history of hypertension and higher incidence of former strokes. Only hypercholesterolemia was identified to be significantly associated with this unusual brain event in our study. The mechanism underlying the development of simultaneous multiple ICHs is not clear although structural and haemodynamic changes of first haemorrhage may be responsible for the second one. Poorer outcome in patients with multiple ICHs can be explained by the concomitant destruction of crossing and non-crossing fiber tracts and bilateral diaschisis phenomenon.

Aged↗

PubMed2004

Rac1 gene mutations in human brain tumours.

AIMS: Rac1 is a member of the Ras superfamily of small GTPase and plays a fundamental role in cytoskeleton reorganization, regulation of gene expression and cell proliferation, and cellular transformation. Though recent studies point to an involvement of rac1 in tumorigenesis, little is known about the alteration of rac1 gene in human brain tumours. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR), TA cloning, and DNA sequencing were performed to detect rac1 gene mutations in the surgical specimens of 45 human brain tumours. RESULTS: Twelve of 45 cases had base changes in the rac1 gene. The frequency of rac1 alterations was seven of 18 meningiomas, three of 14 astrocytomas, one of seven pituitary adenomas, and one of four metastatic brain tumours. No mutation was detected in acoustic neurilemomas. The subtypes of seven meningiomas include three meningotheliomatous, two atypical, one transitional and one angioblastic meningioma. Three astrocytomas had rac1 gene mutation, including one grade II, one grade III, and one grade IV astrocytoma. All of single base changes were transitions, five of them being T to C transitions. Sites of rac1 mutation were found in codons 34, 41 (two cases), 42 (two cases), 43, 44, 46 and 58. These mutations are mainly localized in the putative effector-domain of rac1 gene and may enhance the activity of rac1, which increases the survival of brain tumours. CONCLUSION: Our results suggest that rac1 gene may play a role in some brain tumours of divergent histogenesis and that the alterations of rac1 gene may contribute to tumorigenesis and/or metastasis.

Adolescent↗

PubMed2004

Massive intracerebral air embolism associated with meningitis and lumbar spondylitis: case report.

BACKGROUND: Massive intracerebral air embolism is a rare pathologic state and never in association with meningitis and lumbar spondylitis. To the best of our knowledge, our presented case is the first of a massive intracerebral air embolism associated with meningitis and lumbar spondylitis of Klebsiella pneumonia. CASE DESCRIPTION: A 55-year-old man presented with a high fever and low back pain. Blood culture showed Klebsiella pneumonia. Lumbar computed tomography (CT) revealed discitis at L1-2 and L2-3 levels and paraspinal abscess in which air was found. Despite management with antibiotics, patient's consciousness deteriorated, and brain CT revealed diffuse intravenous air embolism and severe brain swelling. Cerebrospinal fluid (CSF) examination demonstrated bacterial meningitis, and the CSF culture showed Klebsiella pneumonia. Later, septic shock occurred and patient expired. CONCLUSION: Intracerebral air embolism can occur in the Klebsiella pneumonia meningitis that resulted from lumbar spondylitis and sepsis.

Cerebral Veins↗

PubMed2003

The conditional probabilities of survival in patients with anaplastic astrocytoma or glioblastoma multiforme.

BACKGROUND: By the use of conditional probabilities of survival, we studied the yearly survival rates for individual tumor survivors. METHODS: Conditional survival rate was estimated in 114 consecutive patients with anaplastic astrocytoma or glioblastoma multiforme. Conditional probabilities of surviving some years given survival to a specific period of time after craniotomy and 95% confidence intervals were calculated in the individual tumor survivors. RESULTS: The estimated median survival was 30 months for 45 patients with anaplastic astrocytoma and 12 months for 69 patients with glioblastoma multiforme. The conditional probabilities of surviving next one year given survival to 1 year, 2 years, 3 years, 4 years, or 5 years after craniotomy for anaplastic astrocytoma were 86.2%, 75.0%, 85.9%, 77.8%, or 85.7%, respectively; for glioblastoma multiforme 64.8%, 58.7%, 85.7%, 80.0%, or 75.0%, respectively. The conditional probability of surviving to 5 years given survival to 2 years after craniotomy for anaplastic astrocytoma, i.e., surviving an additional 3 years, was 50.1%, which was better than observed 5-year survival rate (28.6%); for glioblastoma multiforme it was 40.2%, which also was better than observed 5-year survival rate (12.4%). CONCLUSIONS: The conditional probability of survival was a good method to clinically predict yearly survival rate for individual tumor survivors. In addition, the method can estimate the probabilities of surviving next some years given survival to a specific period of time after craniotomy. It also showed a more encouraging result than observed survival rate in patients with supratentorial malignant astrocytomas.

Adult↗

PubMed2001

Prevention of cerebral vasospasm by a capsaicin derivative, glyceryl nonivamide, in an experimental model of subarachnoid hemorrhage.

BACKGROUND: Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) remains a major complication in patients suffering from SAH. In our previous study, we reported that stimulating vascular K(+) channel activity prevented the development of cerebral vasospasm. Recent evidence indicates that glyceryl nonivamide (GLNVA), a capsaicin derivative, has a vasorelaxant effect on the aortic vascular smooth muscle due to the release of coronary calcitonin gene-related peptide, which in turn stimulates K(+) channel opening. The purpose of the present study was to examine the preventive effects of GLNVA on vasospasm. METHODS: New Zealand white rabbits were subjected to experimental SAH by injecting autologous blood into the cisterna magna. GLNVA or vehicle was injected intrathecally immediately after the induction of SAH. All animals were killed by perfusion-fixation at 48 hours after SAH. The basilar arteries were removed and sectioned, and their cross-sectional areas were measured. RESULTS: The average cross-sectional areas of basilar arteries were reduced by 69% and 71% in the SAH only and SAH plus vehicle groups, respectively, when compared with the healthy controls. After treatment with 0.35, 1.75, and 3.5 mg/kg GLNVA in rabbits subjected to SAH the average cross-sectional area was decreased by 46%, 12% and 2%, respectively, when compared with the healthy controls. The protective effect of GLNVA achieved statistical significance at all dosages. Morphologically, corrugation of the internal elastic lamina of vessels was often observed in the vehicle-treated group, but was not prominent in the GLNVA-treated groups or healthy controls. CONCLUSION: The findings showed that GLNVA dose-dependently attenuated cerebral vasospasm after SAH in the rabbit. These results suggest that intrathecal administration of GLNVA could be an effective strategy for preventing cerebral vasospasm after SAH.

Animals↗

PubMed2001

Preoperative and postoperative seizures in patients with astrocytic tumours: analysis of incidence and influencing factors.

To evaluate the incidence and influencing factors related to preoperative and postoperative seizures, a retrospective analysis was performed in 190 patients with astrocytic tumours. Preoperative seizures occurred in 50 (26%) patients and 27 (54%) of the m had recurrent seizures. Late-onset seizures developed after craniotomy in 11 (8%) of 140 patients. Seizures at presentation were significantly correlated with age at diagnosis (P=0.0204) and pathological grade of tumour (P=0.0040). The patients aged less than 40 years had a high risk of seizures at presentation (odds ratio=3.076, P=0.0134). Postoperative seizures were significantly associated with the presence of preoperative seizures (P<0.0001), type or duration of preoperative seizures (P<0.0001, P<0.0001, respectively) and serum level of anticonvulsant drug (P=0.0068). However, only the presence of preoperative seizures had a potential for prediction of postoperative seizures when evaluated by logistic regression model (odds ratio=20.859, P=0.0001). Fifty-nine percent of patients with recurrent seizures and 64% of patients with late-onset seizures had seizures which occurred within 6 months after craniotomy. Despite therapeutic anticonvulsant levels, most postoperative seizures were associated with tumour recurrence or haemorrhage. Postoperative seizures commonly occurred relatively soon after craniotomy and prophylactic anticonvulsants should be given. In patients with postoperative seizures, particularly in the presence of therapeutic anticonvulsant level, brain computed tomography should be performed to exclude tumour recurrence or haemorrhage.

Adolescent↗

PubMed2001

Traumatic lumbar spinal subdural hematoma--a case report.

A 74-year-old woman suffered from lower legs weakness after a motor vehicle accident. Magnetic resonance imaging (MRI) on the seventh posttraumatic day, revealed a lumbar spinal subdural hematoma at the level of L4-5. After surgical intervention to remove the subdural hematoma, the patient made a complete recovery.

Aged↗

PubMed2001

Trigeminal neuralgia caused by nasopharyngeal carcinoma with skull base invasion--a case report.

We report a case of nasopharyngeal carcinoma with skull invasion, whose chief complaint was left-sided facial pain, which mimicked trigeminal neuralgia, and in whom there was no palpable neck mass. The magnetic resonance imaging (MRI) revealed an infiltrated lesion with abnormal signal intensity in the left nasopharynx, involving the left retro- and parapharyngeal space. The lesion was pathology-proven through biopsy of the nasopharynx to be a non-keratinizing carcioma. The patient received 6000 rad radiotherapy combined with 5-Fluorouracil(5-FU) and Cisplatin, and has been well after 2 years' follow-up.

Female↗

PubMed2000

Genomic organization and molecular characterization of the human ninein gene.

The centrosome plays a key role in the formation of the mitotic spindle, cell polarity, and cell locomotion. Previously we identified a novel centrosomal associated protein hNinein using GSK-3beta as a bait in the yeast two-hybrid assay. In this report, the hNinein genome was found to correspond to 29 exons of genomic sequence on human chromosome 14q22. Promoter analysis predicts that hNinein contains a TATA, two CCAAT, and three GC boxes. The promoter exhibits the following potential transcription factor binding sites: Sp1, p300, and AP-1. In addition, an alternatively spliced isoform, encoded a 2041-amino-acid protein of 237,900 Da, which was designated hNinein-Lm (GenBank AF302773). The hNinein-Lm genome was found to correspond to 28 exons (2'-29). Amino acid sequence comparison with hNinein showed that hNinein-Lm exhibited an EF-hand Ca2+ binding domain in the N-terminus which similar to mouse ninein. Northern blot showed that this hNinein-Lm isoform was expressed more than hNinein in tissues examined. Differential RT-PCR combining Southern blotting also showed that hNinein-Lm is much more abundant compared to hNinein. Two forms of ninein may also imply the status of ninein associated with a pair of the centrioles in the centrosome structure. Furthermore, molecular characterization shows that human ninein is oligomerized at the C-terminal end which overlapped with GSK-3beta binding site, suggesting that oligomerization of ninein may be regulated by GSK-3beta phosphorylation.

Alternative Splicing↗

PubMed2000

Cloning and characterization of a novel human ninein protein that interacts with the glycogen synthase kinase 3beta.

Using human glycogen synthase kinase 3beta (GSK-3beta) as bait in the yeast two-hybrid system, we identified a novel human centrosome associated protein, hNinein. When the full length cDNA of hNinein was sequenced, it showed that an open reading frame encoded a protein consisting of 2047 amino acids with a predicted molecular mass of 239 kDa. The features of this protein include a potential GTP binding site, a large coiled-coil domain together with four leucine zipper domains and a GSK-3beta binding site. Fluorescence microscopy experiment showed that hNinein is localized in the pericentriolar matrix of the centrosome. In addition, hNinein also showed to react with centrosomal autoantibody sera. Our findings suggest that hNinein may be involved in the formation of centrosome matrix and interacts with the GSK-3beta, implying that it may also be regulated by GSK-3beta phosphorylation signaling.

Amino Acid Sequence↗

PubMed2000

Three rat brain alternative splicing dynamin-like protein variants: interaction with the glycogen synthase kinase 3beta and action as a substrate.

Dynamin-like protein, a large GTP-binding protein, has recently been cloned, and studies have shown that it may be involved in the formation of coated vesicles. In this report, three different alternatively spliced dynamin-like protein variants (DLP1-WT, -11, and -37) from rat brain were identified by reverse transcription/polymerase chain reaction (RT-PCR). One novel rat alternatively spliced variant (DLP1-37), not described previously, was identified. We examined the interaction of these three rat brain dynamin-like protein variants with glycogen synthase kinase 3beta (Gsk-3beta) using the yeast two-hybrid screening, in vitro binding assay, and immunoprecipitation analysis. It was found that all three examined rat brain dynamin-like protein variants can bind to Gsk-3beta. Moreover, in vitro kinase (phosphorylation) assay showed that mammalian dynamin-like protein acts as a substrate for glycogen synthase kinase 3beta. These data suggest that Gsk-3beta may participate in a functional role in dynamin-like proteins in vesicle trafficking.

Alternative Splicing↗

PubMed2000

The recovery potential of central conduction disorder in hypothyroid rats.

In an aim to detect the dysfunction of central nervous system among rats with varied durations of hypothyroidism and to elucidate the recovery potential after thyroxine replacement, a series of BAEP were conducted and compared with age-matched controls. BAEP was performed in five groups of the hypothyroid animals 1, 3, 5, 7, and 9 months after thyroidectomy respectively. Following initial electrophysiological assessment, thyroxine replacement was administered to each group of hypothyroid rats, and BAEP was performed at two month intervals, up to two successive normal studies or six months after the initiation of therapy, whichever came first. Before thyroxine treatment, prolonged I-V interpeak latency was the most consistent abnormal finding in all groups of hypothyroid rats, and longer hypothyroid state correlated well with more severe central conduction disorder. Hearing impairment was also noted among those with long duration of hypothyroidism. After thyroxine replacement, the central conduction dysfunction usually returned to normal if the hypothyroid state was not more than 5 months in duration. However, when hypothyroid state persisted over 7 months or more, there would be an incomplete recovery for central conduction disorder. The present study brings out the concept of 'therapeutic window' in reversing the central nervous dysfunction caused by hypothyroidism in adult rats.

Age Factors↗

PubMed2000

Delayed administration of the K+ channel activator cromakalim attenuates cerebral vasospasm after experimental subarachnoid hemorrhage.

BACKGROUND: Delayed cerebral vasospasm remains an unpredictable and inadequately treated complication of aneurysmal subarachnoid hemorrhage (SAH). Recent evidence indicates that the potassium channel activator cromakalim is capable of limiting cerebral vasospasm in rabbits when administered immediately after experimental SAH (i.e. before spastic constriction has been initiated). However, the ultimate clinical value of cromakalim for treating vasospasm will depend in part on its effectiveness when administered after SAH-induced constriction has already been initiated. The present study examined the effects of cromakalim on vasospasm when treatment was initiated after SAH-induced constriction was underway. METHODS: New Zealand white rabbits were subjected to experimental SAH by injecting autologous blood into the cisterna magna. Cromakalim (0.03, 0.1 or 0.3 mg/kg) or vehicle was injected intravenously at 8 hour intervals beginning 24 hours post-SAH. Animals were killed by perfusion fixation 48 hours after SAH. Basilar arteries were removed and sectioned, and cross-sectional area was measured. FINDINGS: The average cross sectional areas of basilar arteries were reduced by 64% and 68% in the SAH-only and SAH + vehicle groups, respectively. Treatment with cromakalim dose-dependently attenuated SAH-induced constriction. The groups treated with 0.03, 0. 1, and 0.3 mg/kg cromakalim exhibited average decreases in cross-sectional area of 57%, 42%, and 19%, respectively. INTERPRETATION: These findings indicate that cromakalim dose-dependently attenuates cerebral vasospasm when administered 24 hours after experimental SAH in the rabbit. The results suggest K(ATP) channel activators, such as cromakalim. could be of benefit for reversing cerebral vasospasm after aneurysmal SAH.

Animals↗

PubMed2000

Intracranial meningiomas and epilepsy: incidence, prognosis and influencing factors.

In a retrospective study of a consecutive series of 222 surgically treated meningiomas, it was found that 26.6% of the patients presented epilepsy as their initial symptom. In this group, surgical excision of the intracranial meningiomas stopped the epilepsy in about 62.7% of the patients. But approximately one-fifth of the patients with intracranial meningiomas and no history of preoperative epilepsy developed new onset postoperative seizures. Of the patients with early onset of postoperative epilepsy, epilepsy appeared in 66.7% within first 48 h after surgery. Of the patients with postoperative epilepsy, 71.2% were seizure-free following 1 year of anticonvulsant therapy. Regarding preoperative existing factors, intracranial meningiomas located at supratentorium, convexity, and with evidence of or severe peritumoral edema significantly contributed to preoperative epilepsy. And in patients with preoperative epilepsy, those tumors with evidence of or severe perifocal edema and cerebral edema at the operative site were significantly more likely to suffer from postoperative epilepsy.

Adolescent↗

PubMed2000

The conditional survival statistics for survivors with primary supratentorial astrocytic tumors.

BACKGROUND: Relative survival rates can offer a general description of tumor outcome and, traditionally, are used for surveillance and comparison purposes. However, they are not informative for individual tumor survivors. Conditional survival estimates can calculate the probability of surviving next some years given survival to a specific period of time after craniotomy for individual tumor survivors. However, clinically, they have not been used for predicting the tumor outcome. METHODS: We calculated conditional probabilities of survival within 6 years after craniotomy in 112 patients with primary supratentorial astrocytic tumors and evaluated factors affecting the survival time more than 2 years after craniotomy. RESULTS: Our data showed that the conditional probability of survival can predict yearly survival rate when patients survive for a specific period of time. The conditional survival rates within 6 years after craniotomy were always higher than those evaluated by relative survival rates. Overall, the longer the patients survived, the higher the conditional probabilities of surviving sixth year postoperatively were. CONCLUSION: Our study demonstrates the conditional probabilities of survival have good availability and are important estimates for individual tumor survivors.

Adolescent↗

PubMed2000

Differential expression of four human dynamin-like protein variants in brain tumors.

Dynamin-like protein, a large GTP-binding protein, has recently been cloned, and studies have suggested that it is involved in the formation of coated vesicles. In this report, the differential expression of four human dynamin-like protein splice variants (HdynIV-wildtype [WT], -11, -26, and -37) from various brain tumors was identified by reverse transcription/polymerase chain reaction (RT-PCR). One novel variant (HdynIV-11), not described previously, was identified. The four alternatively spliced variants exhibited tissue specificity in normal tissues. The HdynIV-WT was strongly expressed in the brain, whereas HdynIV-37 was expressed in all tissues examined. Moreover, HdynIV-26 was dominant in the liver and apparently overexpressed in all astrocytomas and most meningiomas and adenomas. This report suggests that HdynIV-26 may cause aberrant protein trafficking and alter vesicle formation in brain tumors. Our results also suggest that dynamin-like protein is associated with various brain tumors and, more importantly, that aberrant expression of the HdynIV-26 variant may play a role in brain tumorigenesis.

Adenoma↗