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K M Huang

Publications and source records attributed to K M Huang.

At least 19 recordsLinked to original sources
PubMed2003

Endovascular treatment of brain-stem arteriovenous malformations: safety and efficacy.

Our purpose was to evaluate the safety and efficacy of endovascular treatment of brain-stem arteriovenous malformations (AVMs), reviewing six cases managed in the last 5 years. There were four patients who presented with bleeding, one with a progressive neurological deficit and one with obstructive hydrocephalus. Of the six patients, one showed 100%, one 90%, two 75% and two about 50% angiographic obliteration of the AVM after embolisation; the volume decreased about 75% on average. Five patients had a good outcome and one an acceptable outcome, with a mild postprocedure neurological deficit; none had further bleeding during midterm follow-up. Endovascular management of a brain-stem AVM may be an alternative to treatment such as radiosurgery and microsurgery in selected cases. It may be not as risky as previously thought. Embolisation can reduce the size of the AVM and possibly make it more treatable by radiosurgery and decrease the possibility of radiation injury.

Adolescent↗
PubMed2001

Tissue segmentation-assisted analysis of fMRI for human motor response: an approach combining artificial neural network and fuzzy C means.

The authors have developed an automated algorithm for segmentation of magnetic resonance images (MRI) of the human brain. They investigated the quantitative analysis of tissue-specific human motor response through an approach combining gradient echo functional MRI and automated segmentation analysis. Fifteen healthy volunteers, placed in a 1.5 T clinical MR imager, performed a self-paced finger opposition throughout the activation periods. T1-weighted images (WI), T2WI, and proton density WI were acquired for segmentation analysis. Single-slice axial T2* fast low-angle shot (FLASH) images were obtained during the functional study. Pixelwise cross-correlation analysis was performed to obtain an activation map. A cascaded algorithm, combining Kohonen feature maps and fuzzy C means, was applied for segmentation. After processing, masks for gray matter, white matter, small vessels, and large vessels were generated. Tissue-specific analysis showed a signal change rate of 4.53% in gray matter, 2.98% in white matter, 5.79% in small vessels, and 7.24% in large vessels. Different temporal patterns as well as different levels of activation were identified in the functional response from various types of tissue. High correlation exists between cortical gray matter and subcortical white matter (r = 0.957), while the vessel behaves somewhat different temporally. The cortical gray matter fits best to the assumed input function (r = 0.957) followed by subcortical white matter (r = 0.829) and vessels (r = 0.726). The automated algorithm of tissue-specific analysis thus can assist functional MRI studies with different modalities of response in different brain regions.

Adult↗
PubMed2001

MR imaging of displaced meniscal tears of the knee. Importance of a "disproportional posterior horn sign".

PURPOSE: Meniscal tears associated with displaced fragments are clinically significant. We propose the "disproportional posterior horn sign" as a supportive criterion to identify a posterocentrally displaced meniscal fragment on MR imaging studies. If the meniscal posterior horn in the central portion appears larger than that in the peripheral section, it is considered positive for "disproportional posterior horn sign". MATERIAL AND METHODS: MR images obtained in 42 patients with 43 lesions, confirmed to have displaced meniscal tears, were included in this study. The MR images were retrospectively evaluated for the presence of the "disproportional posterior horn sign", as well as the other known signs. RESULTS: The "disproportional posterior horn sign" was seen in 9 (20.9%) of 43 lesions, including 1 lateral discoid meniscal tear, 5 lateral meniscal tears and 3 medial meniscal tears. Five of them also had other signs of a displaced meniscal fragment. However, the remaining 4 cases only exhibited the "disproportional posterior horn sign". For the other MR signs, the "absent bow tie sign" was detected in 40 (93%) of 43 lesions, the "flipped meniscus sign" in 27 (62.8%) of 43 lesions, the "double posterior cruciate ligament sign" in 17 (39.5%) of 43 lesions and the "notch fragment sign" in 22 (51.2%) of 43 lesions. CONCLUSION: The "disproportional posterior horn sign" is helpful in demonstrating a posterocentrally displaced meniscal fragment, especially when other characteristic signs are unremarkable or absent.

Adolescent↗
PubMed2001

Bilateral anomalous origins of the posterior meningeal artery from the ascending pharyngeal arteries.

We present a rare case of angiographically confirmed dural arteriovenous fistula supplied mainly by the posterior meningeal artery with bilateral anomalous origins from the bilateral ascending pharyngeal arteries. The bilaterality of the origins of the posterior meningeal artery is important in the angiographic diagnosis and management of a dural vascular malformation in the posterior fossa or the posterior part of the falx cerebri.

Adult↗
PubMed2001

Diabetic ketoacidosis and hypogonadotropic hypogonadism in association with transfusional hemochromatosis in a man with beta-thalassemia major.

We report a 23-year-old man with beta-thalassemia major and transfusional hemochromatosis, which manifested as diabetic ketoacidosis and hypogonadotropic hypogonadism. This unusual presentation of diabetic ketoacidosis in hemochromatosis has rarely been reported. Magnetic resonance imaging of the abdomen showed decreased signal intensity in the liver, spleen, and pancreas. In addition, the pituitary gland also showed heterogeneous low signal intensity, compatible with hemochromatosis. He was treated with insulin supplements and pulsatile human chorionic gonadotropin administration. Clinical improvement was noted after hormone replacement. Intensive iron chelation therapy was given to prevent cardiac complications, and to restore his gonadal function. During follow-up, the patient experienced improvement in libido and sexual potency.

Adult↗
PubMed2000

Imaging in the diagnosis and follow-up evaluation of vertebral artery dissection.

The purpose of this report is to discuss the value of ultrasonographic examination in the diagnosis and follow-up evaluation of vertebral artery dissection. We collected data on 8 patients with 11 pathologic vessels: 9 were affected intracranially and 6 were affected extracranially. Four vessels were affected in both intracranial and extracranial segments. Extracranial color-flow duplex sonography could detect abnormalities in every extracranial vertebral artery dissection. Most abnormal findings were non-specific, including severely reduced flow, absence of flow, and absence of diastolic flow. A specific finding (intramural hematoma) was noted in one artery. Abnormal transcranial color-coded sonographic findings included absence of flow, reduced velocity and reversed flow direction. Three intracranial dissecting arteries showed normal findings on transcranial color-coded sonography. Ultrasonographic follow-up study revealed evidence of improvement; this was noted almost exclusively in the extracranial segments of the vertebral artery but infrequently in the intracranial segment. Extracranial color-flow duplex sonography is sensitive in the detection of extracranial vertebral artery dissection, both in initial diagnosis and in follow-up evaluation.

Adult↗
PubMed2000

Factors affecting the outcome of surgical treatment of acromegaly.

PURPOSE: To assess the results of and factors associated with the outcome of surgery for acromegaly. METHODS: We retrospectively examined the medical records of acromegalic patients who underwent trans-sphenoidal adenomectomy at our hospital during the period of January 1991 through August 1997. Preoperative evaluations included measurement of basal serum growth hormone (GH), insulin-like growth factor-I (IGF-I), prolactin (PRL), GH response to oral glucose, and GH and PRL response to bromocriptine, as well as pituitary magnetic resonance (MR) imaging. Postoperative evaluations included measurement of basal serum GH and IGF-I concentrations, and pituitary MR imaging. RESULTS: Thirty patients (14 men) with a mean age of 38 years were included. The mean follow-up period was 50 months (range, 15-90 mo). Ten of the 30 patients (33%) had early postoperative (1 mo after surgery) GH levels of less than 5 ng/mL. Twenty patients (67%) had final postoperative (last follow-up, 15-90 mo after surgery) GH levels of less than 5 ng/mL. Preoperative GH levels were positively correlated with early postoperative GH levels (r = 0.458, p = 0.011) and final postoperative GH levels (r = 0.479, p = 0.007). Early postoperative GH levels were also positively correlated with final postoperative GH levels (r = 0.595, p = 0.001). Tumor grade and stage were not significantly correlated with early or final postoperative GH levels. Thirteen of 21 patients (62%) who had postoperative MR imaging follow-up had residual tumor. There was no surgical mortality. CONCLUSIONS: These results highlight that acromegaly is not easily treated with surgery alone. The preoperative GH level was associated with the surgical outcome.

Acromegaly↗
PubMed1999

Clathrin functions in the absence of heterotetrameric adaptors and AP180-related proteins in yeast.

The major coat proteins of clathrin-coated vesicles are the clathrin triskelion and heterotetrameric associated protein (AP) complexes. The APs are thought to be involved in cargo capture and recruitment of clathrin to the membrane during endocytosis and sorting in the trans-Golgi network/endosomal system. AP180 is an abundant coat protein in brain clathrin-coated vesicles, and it has potent clathrin assembly activity. In Saccharomyces cerevisiae, there are 13 genes encoding homologs of heterotetrameric AP subunits and two genes encoding AP180-related proteins. To test the model that clathrin function is dependent on the heterotetrameric APs and/or AP180 homologs, yeast strains containing multiple disruptions in AP subunit genes, as well as in the two YAP180 genes, were constructed. Surprisingly, the AP deletion strains did not display the phenotypes associated with clathrin deficiency, including slowed growth and endocytosis, defective late Golgi protein retention and impaired cytosol to vacuole/autophagy function. Clathrin-coated vesicles isolated from multiple AP deletion mutants were morphologically indistinguishable from those from wild-type cells. These results indicate that clathrin function and recruitment onto membranes are not dependent upon heterotetrameric adaptors or AP180 homologs in yeast. Therefore, alternative mechanisms for clathrin assembly and coated vesicle formation, as well as the role of AP complexes and AP180-related proteins in these processes, must be considered.

Adaptor Proteins, Vesicular Transport↗
PubMed1999

Solitary vertebral collapse: distinction between benign and malignant causes using MR patterns.

Differentiation of benign from malignant causes of vertebral compression fracture can be difficult at a single location. We studied 37 patients with solitary vertebral collapse (SVC) in the spine using magnetic resonance imaging (MRI). Sixteen of them were found to have a benign cause of SVC, while the remaining 21 were found to have malignancy. The following four MRI characteristics were investigated: ill- or well-defined margin of the intravertebral lesion (P < 0.005); pedicle involvement (P < 0.05); MR enhancement pattern (P < 0.005); and paravertebral soft tissue lesion (PSL) (P < 0.025). It was found that cases of malignant SVC tended to have an ill-defined margin, abnormal signal involvement of the pedicle, a marked and heterogenous MR enhancement pattern, and irregular nodular-type PSL. Pedicle change with expansile lesion totally excluded a benign cause. By using these criteria, we were able to differentiate benign or malignant causes of SVC accurately.

Aged↗
PubMed1999

Diaschisis in chronic viral encephalitis with Koshevnikov syndrome.

The authors report a 61-year-old man with chronic viral encephalitis and Koshevnikov syndrome occurring 42 months after initial symptom of right hemiparesis. Serial computed tomography of the brain showed changes in the attenuation of the left temporal lobe lesion over time. Magnetic resonance images of the brain showed enlargement of left temporoparietooccipital lobes with cortical gyral enhancement on T1-weighted images following intravenous administration of gadolinium-DTPA. 99mTc-HMPAO single-photon emission computerized tomography showed increased radioactivity and hyperperfusion in the left temporoparietal region with paradoxically decreased local tissue perfusion at the contralateral right hemisphere. Follow-up magnetic resonance images of the brain 4 years later showed atrophy of bilateral cerebral hemispheres. We postulate that a "transcallosal diaschisis" with subsequent degeneration is a possible mechanism. A brain biopsy from the left temporal lobe lesion showed pictures compatible with viral encephalitis probably herpes simplex encephalitis.

Atrophy↗
PubMed1999

Cerebral venous thrombosis in patients with nephrotic syndrome--case reports.

The authors describe two cases of cerebral venous thrombosis (CVT) in patients with nephrotic syndrome. The main clinical features of CVT were persistent headache, hemiparesis, and seizure, and the diagnosis was based on magnetic resonance imaging and magnetic resonance angiography. Both showed acquired deficiency of free protein S. The neurologic symptoms remained stationary in the first patient, who received no anticoagulation therapy, but resolved rapidly in the second, treated with intravenous heparin and supplemented with fresh frozen plasma. CVT should be suspected in patients with nephrotic syndrome who present with symptoms of intracranial hypertension or any focal neurologic deficit.

Adolescent↗
PubMed1999

Impact of magnetic resonance imaging on the advancement of medicine.

Magnetic resonance (MR) imaging has had a significant impact in many areas of modern medicine. Because of its good image resolution, tissue characterization, and functional assessment of various organs and systems, MR imaging has become an important modern technology in clinical practice and medical research. MR imaging has great flexibility in viewing anatomic structures in arbitrary imaging planes. With ultrafast MR imaging techniques, images of areas of interest can be obtained in a very short time, with elimination of physiologic motion artifacts. MR angiography obviates the need for catheterization and provides highly detailed images of the vascular anatomy, even of structures as small as the coronary artery. MR cholangiopancreatography provides results comparable to those of endoscopic retrograde cholangiopancreatography in many hepatobiliary diseases. Functional MR imaging is a new tool to evaluate physiologic function. MR spectroscopy has been used to explore the metabolic activity of normal and diseased organs and structures. The applications of MR imaging in clinical medicine and biomedical research are expanding.

Abdominal Neoplasms↗
PubMed1998

Oct-1 binds promoter elements required for transcription of the GnRH gene.

The GnRH gene is exclusively expressed in a discrete population of neurons in the hypothalamus. The promoter-proximal 173 bp of the rat GnRH gene are highly conserved through evolution and are bound by multiple nuclear proteins found in the neuronal cell line, GT1-7, a model for the GnRH-expressing hypothalamic neuron. To explore the protein-DNA interactions that occur within this promoter and the role of these interactions in targeting GnRH gene expression, we have mutagenized individual binding sites in this region. Deoxyribonuclease I protection experiments reveal that footprint 2, a 51-bp sequence that confers a 20-fold induction of the GnRH gene, is comprised of at least three independent protein-binding sites. Transfections of the GnRH promoter-reporter plasmid containing a series of block mutations of footprint 2 into GT1-7 neurons indicate that each of the three putative component sites contributes to transcriptional activity. Mutations in footprint 4 also decrease GnRH gene expression. Footprint 4 and the promoter-proximal site in footprint 2 contain octamer-like motifs, an element that is also present in the neuron-specific enhancer of the rat GnRH gene located approximately 1.6 kb upstream of the promoter. Previous studies in our laboratory have demonstrated that two enhancer octamer sites are bound by the POU-homeodomain transcription factor Oct-1 in GT1-7 cells. We now show that Oct-1 binds the octamer motifs within footprints 2 and 4. Thus, Oct-1 plays a critical role in the regulation of GnRH transcription, binding functional elements in both the distal enhancer and the promoter-proximal conserved region.

Animals↗
PubMed1998

Objective evaluation of oral and maxillofacial sensory nerves.

OBJECTIVE: The purpose of this article is to recommend a set of methods for the clinical objective evaluation of neurosensory nerves and to establish criteria for the clinical objective evaluation of oral and maxillofacial regions in a Chinese population. METHODS: Sensations in the oral and maxillofacial regions of 35 healthy subjects were objectively and quantitatively evaluated by means of two-point discrimination, static light touch, brush directional stroke, and thermal discrimination. RESULTS: Criteria for the clinical neurosensory evaluation were established for the sensations of the oral and maxillofacial regions of healthy Chinese. CONCLUSIONS: Two-point discrimination, static light touch, brush directional discrimination, and thermal discrimination can provide objective, quantitative information for the evaluation of sensory nerve impairment. These convenient methods represent the important tools in the diagnosis and treatment of sensory nerve impairment in oral and maxillofacial regions.

Adolescent↗
PubMed1997

Relationships of orbital computed tomographic findings and activity scores to the prognosis of corticosteroid therapy in patients with Graves' ophthalmopathy.

To elucidate the relationships of orbital computed tomographic findings and activity scores to the prognosis of corticosteroid therapy in patients with Graves' ophthalmopathy, 22 cases were treated with corticosteroid. Orbital computed tomographic was performed before treatment and the maximal muscle areas of rectus muscle bellies were calculated from the coronal images. Activity scores were calculated according to the recommendations of an international ad hoc committee. The clinical severity of the eye disease was based on the NOSPECS classification. Observation of the effectiveness of treatment at 6 months allowed patients to be classified into good responders or poor responders. Twelve of 22 patients (54.5%) belonged to the good responders. The total muscle areas were less in good responders. Although the total muscle areas were significantly correlated with the activity scores, no difference in the activity scores was noted between these two groups. We concluded that although activity score seems to be a predictor of initial responsiveness to anti-inflammatory drugs, the maximal muscle area is a prognostic factor of corticosteroid therapy in patients with Graves' ophthalmopathy.

Adult↗
PubMed1997

Novel functions of clathrin light chains: clathrin heavy chain trimerization is defective in light chain-deficient yeast.

Clathrin is a major coat protein involved in sorting and retention of proteins at the late Golgi and in endocytosis from the cell surface. The clathrin triskelion contains three heavy chains, which provide the structural backbone of the clathrin lattice and three light chains, which are thought to regulate the formation or disassembly of clathrin coats. To better understand the function of the clathrin light chain, we characterized yeast strains carrying a disruption of the clathrin light chain gene (CLC1). Light chain-deficient cells showed phenotypes similar to those displayed by yeast that have a disruption in the clathrin heavy chain gene (CHC1). In clc1-delta cells, the steady state level of the clathrin heavy chain was reduced to 20%-25% of wild-type levels and most of the heavy chain was not trimerized. If CHC1 was overexpressed in clc1-delta cells, heavy chain trimers were detected and several clc1-delta phenotypes were partially rescued. These results indicate that the light chain is important for heavy chain trimerization and the heavy chain still has some function in the absence of the light chain. In yeast, deletion of CHC1 is lethal in strains carrying the scd1-i allele, while strains carrying the scd1-v allele can survive without the heavy chain. In previous studies we isolated several multicopy suppressors of inviability of chc1-delta scd1-i cells. Surprisingly, one of these suppressors, SCD4, is identical to CLC1. Overexpression of CLC1 in viable chc1-delta scd1-v strains rescued some but not all of the phenotypes displayed by these cells. In the absence of the heavy chain, the light chain was not found in a high molecular mass complex, but still associated with membranes. These results suggest that the light chain can function independently of the clathrin heavy chain in yeast.

Clathrin↗
PubMed1997

Magnetic resonance imaging in patients with hemodialysis-related arthropathy.

From April 1993 to December 1993, we prospectively studied the knees of 15 patients (mean age, 48 +/- 11 yr) receiving long-term hemodialysis (mean duration, 9 +/- 4 yr) using magnetic resonance imaging (MRI) techniques including, T1 weighted spin-echo, multiplanar gradient recalled, and postcontrast T1 with chemical shift-selective, fat-saturation pulse sequences. Analysis of these images revealed that the three findings most indicative of hemodialysis-related arthropathy were intramedullary, cortical and soft tissue lesions. Knee pain was significantly correlated with the presence of soft tissue lesions. Cortical lesions were usually associated with soft tissue lesions. Inflammatory changes adjacent to soft tissue lesions were demonstrated in postcontrast studies in all patients with soft tissue lesions. Increases in water content in those lesions appeared to increase the signal intensity. Our results indicate that MRI is useful in demonstrating the extent of hemodialysis-related arthropathy involvement, especially in hemodialysis patients suffering from knee pain.

Adult↗