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Biomedical subjects

C L Lin

Publications and source records attributed to C L Lin.

At least 109 records · Page 6Linked to original sources

Primary intraventricular hemorrhage in adult--an analysis of 24 cases.

Primary intraventricular hemorrhage in adults is rare, comprising only about 3.1 % of all intracranial hemorrhage. One of the major management tasks is to find out whether the hemorrhage is secondary to underlying structural vascular abnormality, such as arteriovenous malformation (AVM) and aneurysm, so that appropriate treatment can be carried out to prevent rebleeding. We retrospectively analyzed 24 patients with computerized tomography findings of intraventricular hemorrhage in our hospital from 1991 to 1996. Cerebral angiography was performed in eighteen patients. Eight patients (57%) had positive angiographic findings (five were AVM and three were aneurysm). The angiographic yield was five of seven patients (72%) younger than 45 years of age and three of eleven (27%) older than 45 years of age. On the basis of our results, we suggest that cerebral angiography should be considered for all primary intraventricular hemorrhage patients who are younger than 45 years old.

Adolescent↗

Effects of thrombin on the growth, protein synthesis, attachment, clustering and alkaline phosphatase activity of cultured human periodontal ligament fibroblasts.

Previous studies have indicated that thrombin can activate pulp cells, including fibroblasts. Because pulp cells and periodontal ligament (PDL) fibroblasts can express thrombin receptor mRNA, the specific aim of this study was to determine whether thrombin can activate the growth, attachment, protein synthesis, alkaline phosphatase activities and cellular clustering of cultured human PDL fibroblasts. Thrombin can stimulate the growth of PDL fibroblasts in a dose dependent manner (as analyzed by MTT assay). At concentrations of 5 and 10 U/ml, thrombin increased the cell numbers to 141% and 153% greater than that of the control after 5 days of incubation, respectively. Thrombin (5-20 U/ml) also stimulated the protein synthesis rate (assayed by [3H]proline incorporation) to 1.88-2.13 fold that of the control. However, pretreatment of PDL fibroblasts with thrombin (1-20 U/ml) could not promote the attachment of PDL fibroblasts to type I collagen and fibronectin. Moreover, thrombin could induce clustering of PDL fibroblasts within a concentration range of 5-20 U/ml. However, thrombin (1-20 U/ml) exerted neither stimulatory nor inhibitory effect on cellular alkaline phosphatase activities. In conclusion, it appears that the presence of thrombin seems to have effects on PDL fibroblasts in terms of cell growth, protein synthesis and cell clustering. This suggests that thrombin might be important in the early healing process of periodontium following periodontal surgery.

Alkaline Phosphatase↗

The isolation and characterization of purified heterocomplexes of recombinant retinoic acid receptor and retinoid X receptor ligand binding domains.

Retinoic acid exerts many of its biological effects by interaction with heterocomplexes of nuclear retinoic acid receptors (RARs) and retinoid X receptors (RXRs). To further examine this interaction, a glutathione S-transferase (GST) fusion protein containing the ligand binding domain of human RXR alpha has been used to copurify the ligand binding domain of human RAR gamma by affinity chromatography over glutathione-agarose. Complexes of recombinant RAR-RXR ligand binding domains retaining full ligand binding capacity were purified, and their interactions with various retinoids were characterized by fluorometric titration and photoaffinity labeling. Analyses of the distribution of limiting amounts of [3H]-all-trans-retinoic acid between cytoplasmic retinoic acid binding proteins, CRABP-I and CRABP-II, and the purified heterocomplexes indicate that all-trans-retinoic acid binds with comparable affinity to CRABP-I and the heterocomplexes, but with approximately 10-fold less affinity to CRABP-II. The aromatic retinoid acitretin, which is used in the treatment of psoriasis, binds relatively poorly to the purified heterocomplexes, although it binds with high affinity to the CRABPs. Acitretin displaces [3H]-all-trans-retinoic acid from the CRABPs and increases retinoic acid occupancy of the heterocomplexes. These results suggest that certain retinoids could potentially perturb the distribution of endogenous retinoic acid between the CRABPs and the nuclear receptors and thus affect retinoid signaling. The purified recombinant complexes should provide a useful model system for further structural analysis of the dimerization interface between the RAR and RXR ligand binding domains.

Acitretin↗

19F-NMR studies of retinol transfer between cellular retinol binding proteins and phospholipid vesicles.

The cellular retinol binding proteins, CRBP and CRBP II, are implicated in the cellular uptake of retinol and intracellular trafficking of retinol between sites of metabolic processing. 19F-NMR studies of retinol transfer between CRBP and CRBP II and phospholipid vesicles, using either fluorine-labeled ligand or protein, demonstrated that there was significantly more transfer of retinol from CRBP II to lipid vesicles than from CRBP. Differences in how readily protein-bound retinol is released to lipid bilayers may lead to differences in how these two proteins modulate intracellular retinol metabolism.

Animals↗

Leptospirosis: an ignored cause of acute renal failure in Taiwan.

Leptospirosis, caused by a spirochete, is the most common zoonosis in domestic or wild animals. Animals excrete infected urine in soil or water and may cause human infections through abrased wound, mucosa, conjunctiva, or by swallowing contaminated water. Clinical presentations of leptospirosis are mostly subclinical. Five to ten percent of leptospirosis are fatal, causing fever, hemorrhage, jaundice, and acute renal failure (Weil's syndrome). Leptospirosis has been ignored as a cause of acute renal failure in Taiwan. We report two patients with leptospirosis who presented with high fever, abdominal pain, jaundice, and acute renal failure. Patient 1 died on day 12 of admission of multiple organ failure associated with pancytopenia, hypogammaglobulinemia, and reactive hemophagocytosis. Leptospirosis was recognized after death. Patient 2 was admitted with similar presentations 2 weeks later. Penicillin and doxycycline were given early in the course, and azotemia, jaundice, respiratory failure, and aseptic meningitis gradually improved. Renal biopsy showed interstitial nephritis. Several tubular clearance tests showed proximal tubular defect with severe bicarbonate wasting (FeHCO3- 20.9%) and incomplete type II renal tubular acidosis without affecting the distal nephron. After 80 days of treatment, this patient was discharged with recovery of conscious level and renal function. This is the first leptospirosis patient with detailed tubular functional and morphological studies of the kidney. Diagnosis of leptospirosis was made by microscopic agglutination test (MAT) for antibody to leptospira and by polymerase chain reaction (PCR) for leptospira DNA in blood and urine (interrogans serogroup australis in case 1 and Leptospira borgpetersenii serogroup ballum in case 2). Because active surveillance has resulted in 13 cases diagnosed as leptospirosis islandwide thereafter, underestimation and ignorance of leptospirosis as a cause of acute renal failure may occur in Taiwan. Therefore, an area with a low leptospirosis incidence may actually have a very high incidence. Leptospirosis should be suspected in febrile patients with jaundice and renal failure when pathogens cannot be identified by traditional culture for microorganisms.

Abdominal Pain↗

Cellular and synaptic localization of the neuronal glutamate transporters excitatory amino acid transporter 3 and 4.

Glutamate transport is a primary mechanism for the synaptic inactivation of glutamate. Excitatory amino acid transporter 4 (EAAT4) is a novel glutamate transporter with properties of a ligand-gated chloride channel that was recently cloned from human brain. The present study was an investigation of the protein expression and cellular localization of EAAT4 in human and rat brain, and comparison with another neuronal glutamate transporter, EAAT3 (rabbit excitatory amino acid carrier 1; EAAC1). Regional immunoblot analysis of EAAT4, using a monospecific oligopeptide (carboxy-terminal) affinity-purified polyclonal antibody, revealed that the protein was restricted to the central nervous system. The EAAT4 protein was largely expressed in cerebellum, with a much lower expression in hippocampus, neocortex, striatum, brain stem and thalamus. Immunohistochemical studies showed intense EAAT4 immunoreactivity in the human and rat cerebellar Purkinje cells with a somatodendritic localization. Other brain regions including neocortex, hippocampus, striatum showed faint neuropil staining of EAAT4. Immunogold localization identified EAAT4 protein at plasma membranes of Purkinje cell dendrites and spines. In the hippocampus and neocortex, EAAT4 immunoreactivity was found mainly at small calibre dendrites. Rarely, EAAT4 immunoreactivity was found in astrocytic cell processes of forebrain. In the cerebellum, EAAT4 localization partly overlapped with the neuronal localization of EAAT3 (EAAC1). Immunoreactivity for EAAT3 was enriched in the somatodendritic compartment of the Purkinje cells like EAAT4, but EAAT3 was also found in Purkinje cell axons and in boutons in deep cerebellar nuclei, as well as in granular cells and stellate cells. Our results indicate that EAAT4 protein is largely localized to cerebellar cortex and lower levels of EAAT4 protein are present in forebrain by immunoblot and immunohistochemistry. Both neuronal glutamate transporter EAAT3 (EAAC1) and EAAT4 are located at somatodendritic compartment of Purkinje cells, and probably contribute to glutamate re-uptake mechanisms at Purkinje cell synapses.

Aged↗

Urinary free cortisol and cortisone determined by high performance liquid chromatography in the diagnosis of Cushing's syndrome.

To determine the efficacy of cortisol and its metabolite, cortisone, measured simultaneously by high performance liquid chromatography (HPLC) in the diagnosis of Cushing's syndrome, we retrospectively reviewed the histories of 29 surgically proven Cushing's syndrome patients (20 Cushing's disease, 5 ectopic ACTH syndrome, and 4 adrenal Cushing's syndrome) and 6 patients with exogenous Cushing's syndrome. These 35 patients had urinary free cortisol determined by both HPLC and competitive binding methods. The efficacy of the HPLC assay using cortisol alone was equivalent to that of the competitive binding assay; 22 of 29 (76%) patients had increased cortisol. Cortisone also aided in the diagnosis; 25 of 29 (86%) had increased cortisone. Twenty-seven of the 29 (93%) patients had either both cortisone and cortisol (n = 19) or at least 1 of the 2 (n = 8) increased. All 6 patients with exogenous Cushing's syndrome had suppressed urinary free cortisol, cortisone, and the presence of prednisone and prednisolone. In the competitive binding assay, all exogenous Cushing's patients had falsely increased cortisol results. In conclusion, urinary free cortisol plus cortisone determined simultaneously by HPLC added a new dimension to the diagnosis of Cushing's syndrome. It should be considered when exogenous Cushing's syndrome is suspected or when only one urinary cortisol test is allowed to be ordered.

ACTH Syndrome, Ectopic↗

Purification and characterization of a glucose-tolerant beta-glucosidase from Aspergillus niger CCRC 31494.

An extracellular glucose-tolerant beta-glucosidase was purified to homogeneity by alcohol fractionation and preparative isoelectric focusing from Aspergillus niger CCRC 31494. The enzyme was a dimeric protein with a subunit of 49,000, and had its optimum activity at pH 5.0 and 55 degrees C. The enzyme was completely inhibited by 5 mM Ag+. Thiol groups and serine residues were not essential for its activity. Low concentrations of alcohols (10%) except for methanol could activate the enzyme. It was very specific for para-nitrophenyl-beta-D-glucoside (pNPG) and cellobiose. However, the enzyme also had some beta-xylosidase activity, but showed no activity towards alpha-linked glycosidic substrates. The Vmax of 124.4 U/mg and 21.6 U/mg were found for pNPG (Km = 21.7 mM) and para-nitrophenyl-beta-D-xyloside (pNPX) (Km = 14.2 mM), respectively. The enzyme was tolerant to glucose inhibition with a Ki of 543 mM, while fructose, galactose, mannose, and xylose were not inhibitory.

Aspergillus niger↗

Speed and accuracy of eye-gaze pointing.

The current experiment examined the speed-accuracy trade-off of saccadic movement between two targets. Ten subjects looked alternately at two targets as fast and as accurately as possible for 2 min. under different conditions of target size, distance between targets, and direction of eye movement. Saccadic movement of the left eye was tracked and recorded with an infrared eye monitoring device to compute the starting position, ending position, and duration of each saccadic movement. Eye-movement time was significantly related to target size and distance between targets, but the speed-accuracy trade-off was significantly different from that predicted by Fitts' Law. Reaction time was not significantly changed by the direction of eye movement.

Adult↗

Aiming accuracy of the line of gaze and redesign of the gaze-pointing system.

The current experiment tested the aiming accuracy of the eye for targets at nine different positions and of two different sizes. The left eye was tracked to record the line of gaze with an infrared eye-monitoring device. For each subject, horizontal shift, vertical shift, standard deviations of the X and Y coordinates, and 95th percentile of the horizontal and vertical shifts from the nine target centers were calculated to indicate the precision, accuracy, and possible design limits of the gaze points. Analysis showed that the target's position had a strong effect on the vertical shift, standard deviations of the Y coordinate, and 95th percentile of the vertical shift. The effect of target size was not significant on any of the dependent measures. The research findings have important implications for the redesign of the gaze-pointing device. Visual targets appearing below the horizontal line of sight should be larger than those above. Based on the 95th percentile of the horizontal and vertical shifts, targets should be approximately 2.0 degrees wide and 2.4 degrees long above or coinciding with the horizontal line of gaze and 2.6 degrees wide and 3.9 degrees (cm) long below the horizontal line of gaze.

Equipment Design↗

Increased parathyroid hormone-related peptide in patients with hypercalcemia associated with islet cell carcinoma.

OBJECTIVE: To report the high prevalence of increased parathyroid hormone-related peptide (PTHrP) in patients with islet cell carcinoma and associated hypercalcemia. DESIGN: We conducted a retrospective study of PTHrP levels in patients with hypercalcemia and eucalcemia associated with islet cell carcinoma and compared these findings with those in healthy subjects. MATERIAL AND METHODS: Using a sensitive PTHrP immunochemiluminometric assay, we measured PTHrP levels in 17 patients with islet cell carcinoma and 110 healthy subjects. The differences between PTHrP levels in patients with normal and those with high serum calcium concentrations were analyzed statistically. RESULTS: PTHrP levels were significantly higher (P < 0.01) in 10 patients with hypercalcemia and islet cell carcinoma (median, 14.0 pmol/L; range, undetectable to 40.1) than in 7 patients with eucalcemia and islet cell carcinoma (median, undetectable; range, undetectable to 1.3 pmol/L) or in the 110 healthy subjects (median, undetectable; range, undetectable to 4.2 pmol/L). The range of increased PTHrP levels in hypercalcemic islet cell carcinoma was 2 to 20 times the upper normal limit (2.0 pmol/L). Decreased PTHrP and serum calcium and increased parathyroid hormone levels were demonstrated in two patients after effective therapy. For all seven eucalcemic patients with islet cell carcinoma, PTHrP levels did not differ significantly from those in healthy subjects. CONCLUSION: PTHrP levels are increased in a substantial proportion of patients with hypercalcemia and islet cell carcinoma and seem to decrease after treatment of the underlying tumor. Measurement of PTHrP levels may be useful for confirming the diagnosis of hypercalcemia associated with malignant disease and for monitoring of therapy.

Adult↗

Coexistent mitral stenosis and coronary artery fistula presenting as myocardial ischemia: case report.

We report a 50-year-old female case of mitral stenosis with congenital coronary artery fistula communicating the left anterior descending artery to pulmonary artery. In reviewing the literature, mitral stenosis associated with coronary artery fistula is rare. The case was initially treated medically for congestive heart failure. The electrocardiogram revealed severe myocardial ischemia and no obvious etiology was found clinically. The coronary angiogram demonstrated the diagnosis of coronary artery fistula. Myocardial ischemia improved markedly after surgical correction of the valvular disease and the fistula. The patient continued to do well during 2 years and 10 months follow up. The concomitant mitral stenosis masked the symptoms of coronary artery fistula, and made us fall to diagnose the condition initially. Valvular heart disease associated with severe myocardial ischemia without obvious atherosclerotic stenosis of coronary artery reminded us of the possibility of coronary artery fistula, though it has rarely been reported.

Arterio-Arterial Fistula↗

Unusual large cystic acoustic neurinomas: report of two cases.

Two rare cases of large cystic acoustic neurinomas are reported in this paper. Such cases are sometimes misdiagnosed preoperatively because their computed tomography appearances resemble those of other cystic lesions in the cerebellopontine angle. The diagnosis of acoustic neurinoma should be kept in mind if one finds a large cystic cerebellopontine angle tumor, even if there are no typical clinical symptoms or erosion of the internal auditory canal. Magnetic resonance imaging of large cystic acoustic neurinomas are also described in this paper.

Adult↗

Nontraumatic intracerebral hemorrhage in young adult.

We reviewed our experience with 91 patients aged 15 to 40 years with nontraumatic intracerebral hemorrhage (ICH) from January 1991 through December 1994 and found more than ten presumed causes for the nontraumatic ICH in 68 patients (74.7%). The leading two causes were arterial hypertension and ruptured arteriovenous malformations. Most cases of ICH were lobar and putaminal. Of the lobar hemorrhages, 26.5% resulted from ruptured arteriovenous malformations. Of the putaminal hemorrhages, we found 60% resulted from arterial hypertension. Arteriography was performed in 36 patients, and was diagnostic in 23. A history of drug abuse was found in 3 patients. The survival rate was 82.4% at 1 month, 78.0% at 6 months and 76.9% at 1 year. The in-hospital survival rate of all patients in this study was 78.0%. The outcome was determined at one month after hemorrhage. Thirty-two percent of our cases made a good recovery (back to normality), 35% a fair recovery (moderately disabled but independent), 15% a poor recovery (severely disabled and dependent), and 18% died. Arterial hypertensive hemorrhage accounted for almost 30% of our young ICH patients which reminds us of the importance of regular control of blood pressure even in the young adults. Arteriography performed early in the course of nontraumatic ICH in young adults, particularly in lobar hemorrhages, is a valuable adjunct in determining cause. Although the details of history of drug abuse were frequently lacking, physicians should keep this abuse in mind as a possible cause for nontraumatic ICH.

Adolescent↗

Risk factors associated with coronary artery stenosis among patients with chest pain in eastern Taiwan.

To analyze the risk factors for coronary artery stenosis among patients who were admitted to the hospital with chest pain in eastern Taiwan, we retrospectively reviewed the clinical data of 444 patients who received coronary arteriography, including 62 aborigines. Results indicated that there were 268 patients (64%) with coronary stenosis. Male to female ratio, mean age, pack-years of cigarette smoking, and hypertension were significantly higher in patients with coronary stenosis (CS group) than in patients without coronary stenosis (control group). There were also significant differences in the serum levels of total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol between the CS and control groups. The total cholesterol and low-density lipoprotein cholesterol of both the CS and control groups were lower than those reported in western Taiwan. The prevalence of coronary stenosis among Taiwanese patients who presented with chest pain was significantly higher than in aborigines (64% vs 38%), although there were no significant differences in common risk factors between these two ethnic groups. These results revealed that the common risk factors in eastern Taiwan were the same as those reported here and suggest that race may be an important risk factor for coronary stenosis.

Analysis of Variance↗

Intrasellar and suprasellar germinoma.

A 15-year-old male was admitted to our hospital with diabetes insipidus, headache and bitemporal hemianopia and a computed tomogram (CT) revealed an intra- and suprasellar tumor. Differential diagnosis between large intra- and suprasellar germinoma and pituitary adenomas is quite difficult based on CT. After comparing our case with past literature of reported cases of intrasellar and suprasellar germinoma, we found that an enhanced mass posterior to the pituitary gland on the midsagittal magnetic resonance imaging (MRI) and absence of the high signal intensity of the posterior lobe on T1-weighted MRI in patients with diabetes insipidus indicated germinoma rather than a pituitary adenoma. Transphenoid approach and appropriate radiotherapeutic management were administered with a good result.

Adolescent↗

Activation of glycosylasparaginase. Formation of active N-terminal threonine by intramolecular autoproteolysis.

The activation mechanism of glycosylasparaginase of Flavobacterium meningosepticum has been analyzed by site-directed mutagenesis and activation of purified precursors in vitro. Mutation of Thr-152 to Ser or Cys leads to gene products that are not activated in vivo but are activated in vitro because processing of the mutant precursors is inhibited by certain amino acids in the cell. Kinetic studies reveal that activation is an intramolecular autoproteolytic process. The involvement of His-150 and Thr/Ser/Cys-152 in activation suggests that autoproteolysis resembles proteolysis by serine/cysteine proteases. Multiple functions of the highly conserved active threonine residue are implicated.

Amino Acid Sequence↗