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J W Lin

Publications and source records attributed to J W Lin.

At least 37 records · Page 2Linked to original sources
PubMed2000

Presynaptic Ca(2+) influx at the inhibitor of the crayfish neuromuscular junction: a photometric study at a high time resolution.

Presynaptic calcium influx at the inhibitor of the crayfish neuromuscular junction was investigated by measuring fluorescence transients generated by calcium-sensitive dyes. This approach allowed us to correlate presynaptic calcium influx with transmitter release at a high time resolution. Systematic testing of the calcium indicators showed that only low-affinity dyes, with affinities in the range of micromolar, should be used to avoid saturation of dye binding and interference with transmitter release. Presynaptic calcium influx was regulated by slowly increasing the duration of the action potential through progressive block of potassium channels. The amplitude of the calcium transient, measured from a cluster of varicosities, was linearly related to the duration of the action potential with a slope of 1.2. Gradual changes in potassium channel block allowed us to estimate the calcium cooperativity of transmitter release over a 10-fold range in presynaptic calcium influx. Calcium cooperativity measured here exhibited one component with an average value of 3.1. Inspection of simultaneously recorded presynaptic calcium transients and inhibitory postsynaptic currents (IPSCs) showed that prolonged action potentials were associated with a slow rising phase of presynaptic calcium transients, which were matched by a slow rate of rise of IPSCs. The close correlation suggests that fluorescence transients provide information on the rate of calcium influx. Because there is an anatomic mismatch between the presynaptic calcium transient, measured from a cluster of varicosities, and IPSC, measured with two-electrode voltage clamp, macropatch recording was used to monitor inhibitory postsynaptic responses from the same cluster of varicosities from which the calcium transient was measured. Inhibitory postsynaptic responses recorded with the macropatch method exhibited a faster rising phase than that recorded with two-electrode voltage clamp. This difference could be attributed to slight asynchrony of transmitter release due to action potential conduction along fine branches. In conclusion, this report shows that fluorescence transients generated by calcium-sensitive dyes can provide insights to the properties of presynaptic calcium influx, and its correlation with transmitter release, at a high time resolution.

4-Aminopyridine↗
PubMed2000

Villous adenomas of the urinary tract: report of two cases.

Villous adenomas are rare tumors of the urinary tract. They are morphologically identical to their counterpart in the colon. The histogenesis and malignant potential are uncertain. We report on 2 cases, 1 each in the urethra and bladder. The first is a 57-year-old male who complained of an acute attack of urinary retention. A papillary tumor, measuring 3.0 x 2.0 cm, was found in the prostatic portion of the urethra by cystoscopy, and the tumor was removed transurethrally. The second case, a 33-year-old male, was a victim of chronic pyelonephritis with severe hydronephrosis resulting from a left renal staghorn stone. A papillary tumor was noted on the dome of the urinary bladder. The tumor, measuring 2.0 x 2.0 cm, was resected by transurethral resection. No recurrence or malignant transformation has been found during the follow-up period. The features of morphology, immunohistochemistry, and histochemistry were well studied. Staining by periodic acid-Schiff (PAS) stain, Alcian blue at pH 1.0, and Alcian blue at pH 2.5 were all positive. The carcinoembryonic antigen was strongly positive in the neoplastic glands, especially in the luminal border. We also review the previous literature and discuss the histogenesis, diagnosis, and treatment.

Adenoma, Villous↗
PubMed1999

Regulation of NMDA receptors by an associated phosphatase-kinase signaling complex.

Regulation of N-methyl-D-aspartate (NMDA) receptor activity by kinases and phosphatases contributes to the modulation of synaptic transmission. Targeting of these enzymes near the substrate is proposed to enhance phosphorylation-dependent modulation. Yotiao, an NMDA receptor-associated protein, bound the type I protein phosphatase (PP1) and the adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (PKA) holoenzyme. Anchored PP1 was active, limiting channel activity, whereas PKA activation overcame constitutive PP1 activity and conferred rapid enhancement of NMDA receptor currents. Hence, yotiao is a scaffold protein that physically attaches PP1 and PKA to NMDA receptors to regulate channel activity.

A Kinase Anchor Proteins↗
PubMed1999

Acute disseminated histoplasmosis complicated with hypercalcaemia.

A case of acute progressive disseminated histoplasmosis complicated with hypercalcemia is reported and the literature is reviewed. This and the previously reported cases imply that physicians should have a higher index of suspicion for this infection and the probable underlying diseases resulting from impaired cellular-mediated immunity when encountering patients with hypercalcaemia.

Fatal Outcome↗
PubMed1999

Results of elective abdominal aortic aneurysm repair in the 1990s: A population-based analysis of 2335 cases.

OBJECTIVE: The safety and efficacy of conventional abdominal aortic aneurysm (AAA) repair are undergoing increased examination in parallel with the development of less invasive repair methods. Because most published studies of elective AAA repair report operations performed in tertiary referral institutions and thus may not reflect the outcome in the surgical community at large, the current population-based study was undertaken to document the results obtained across a broad spectrum of clinical practice in a defined geographic area and to examine the factors that influence the outcomes. METHODS: The Maryland Health Services Cost Review Commission database was used to identify all the elective AAA repairs that were performed in all the nonfederal acute care hospitals in the state from 1990 to 1995. RESULTS: Elective AAA repair was performed on 2335 patients (mean age, 70.4 years) in 46 of the 52 (88%) nonfederal acute care hospitals in the state, including seven high-volume (>100 cases), nine moderate-volume (50 to 99 cases), and 30 low-volume (<50 cases) institutions. The in-hospital mortality rate was 3.5% and increased significantly with advancing age: less than 65 years, 2.2%; 65 to 69 years, 2.5%; 70 to 79 years, 3.5%; and more than 80 years, 7.3% (P =.002). Mortality rates were higher for women (4.5% vs 3.2%; P =.17), for blacks (6.7% vs 3.2%; P =.046), and for patients with renal failure (11.8% vs 3. 4%; P =.11) but not for patients with hypertension, diabetes, heart disease, and pulmonary disease. The operative mortality rate was inversely correlated with hospital volume (4.3% in low-volume hospitals, 4.2% in moderate-volume hospitals, and 2.5% in high-volume hospitals; P =.08), although no differences were noted in the mean ages or comorbidity levels of patients who underwent operations in these three hospital populations. The operative mortality rate was inversely correlated with the experience of the individual surgeon: one case, 9.9%; two to nine cases, 4.9%; 10 to 49 cases, 2.8%; 50 to 99 cases, 2.9%; and more than 100 cases, 3.8% (P =.01). Multivariate analysis results identified patient age (P =. 002), low hospital volume (P =.039), and very low surgeon volume (P =.01) as independent predictors of operative mortality. The mean length of stay and mean hospital charges were 10.6 days and $17,589 and decreased with increasing surgeon volume: one case, 22.7 days/$32,800; two to nine cases, 10.6 days/$18,509; 10 to 49 cases, 10.0 days/$16,611; 50 to 99 cases, 10.9 days/$17,843; and more than 100 cases, 9.6 days/$16,682 (P <.0001/P <.0001). CONCLUSION: Elective AAA repair is a safe procedure in contemporary practice in Maryland. Operative risk is increased among the elderly and when operations are performed by surgeons with very low volumes or in low-volume hospitals. Hospital lengths of stay were shorter and charges were lower when elective AAA repair was performed by surgeons with higher volumes.

Adult↗
PubMed1999

Identification of a novel beta-lactamase produced by Xanthomonas campestris, a phytopathogenic bacterium.

The Xanthomonas campestris pv. campestris 11 chromosome encodes a periplasmic beta-lactamase of 30 kDa. Gene replacement and complementation confirmed the presence of this enzyme. Its deduced amino acid sequence shows identity and conserved domains between it and Stenotrophomonas maltophilia L2 and other Ambler class A/Bush group 2 beta-lactamases. Southern hybridization detected a single homologous fragment in each of 12 other Xanthomonas strains, indicating that the presence of a beta-lactamase gene is common among xanthomonads.

Amino Acid Sequence↗
PubMed1999

Adult ovarian granulosa cell tumors: spectrum of sonographic and CT findings with pathologic correlation.

OBJECTIVE: The objective of this study was to evaluate the spectrum of sonographic and CT findings in adult ovarian granulosa cell tumors with pathologic correlation. MATERIALS AND METHODS: Transabdominal sonograms and CT scans in 13 patients with pathologically proven adult ovarian granulosa cell tumors were retrospectively reviewed. Morphologic characteristics of the lesions shown on sonography and CT were correlated with the histopathologic findings. RESULTS: On the basis of sonographic and CT findings, 13 cases of adult ovarian granulosa cell tumor were categorized into five morphologic patterns: multilocular cystic (n = 6), thick-walled unilocular cystic (n = 2), thin-walled unilocular cystic (n = 1), homogeneously solid (n = 2), and heterogeneously solid (n = 2) masses. Histopathologically, the multilocular cystic masses were characterized by a predominately macrofollicular pattern of granulosa cells and multiple cystic spaces with watery fluid or hemorrhage. Unilocular central cystic masses seen on CT correlated pathologically with confluence and expansion of the cystic spaces. Homogeneously solid masses seen on sonography and CT were correlated with evenly distributed trabecular or diffuse patterns in the tumor cells. Intratumoral bleeding, infarcts, fibrous degeneration, and irregularly arranged tumor cells yielded heterogeneously solid tumors. CONCLUSION: Adult ovarian granulosa cell tumors have a varied histologic appearance and a varied arrangement of tumor cells, both of which can create a spectrum of imaging manifestations. Appreciation of these manifestations is helpful in the diagnosis of this tumor.

Female↗
PubMed1998

Identification and analysis of the regulatory region R&R* with the cnf1 gene encoding the cytotoxic necrotizing factor type 1 that closely links to the lux regulon of Vibrio fischeri.

Nucleotide sequence of the regulatory region R&R* and the partial 5'-end of the cnf1 gene (GenBank Accession No. AF023157) of Vibrio fischeri ATCC 7744 has been determined, and the cytotoxic necrotizing factor 1 (CNF1) encoded by the cnf1 gene is deduced. Alignment and comparison of the cytotoxic necrotizing factor 1s of V. fischeri and E. coli show that they are homologous. Nucleotide sequence reveals that the cnf1 gene is closely linked to the lux regulon in genome; the gene order of the cnf1 gene and the lux regulon is <--cnf1-R&R*<--rrn-<--luxR-R&R-luxI-luxC-luxD -luxA-luxB-luxE-luxG-omega-->, whereas R&R is the regulatory region of the lux regulon, and R&R* is the regulatory region of the cnf1 gene; the sequence approximately 2 kb lay between the luxR gene of the lux regulon and the cnf1 gene is an rrn-like operon. It is unexpected to find the cnf1 gene in V. fischeri, since the CNF1 protein enables necrosis; the marine luminous bacterium V. fischeri is never to be identified as a pathogenic microbe. The cnf1 gene might be concerned with symbosis of the luminous bacteria and host fishes.

Amino Acid Sequence↗
PubMed1998

Neuromodulators enhance transmitter release by two separate mechanisms at the inhibitor of crayfish opener muscle.

A presynaptic voltage control method has been used to investigate the modulatory effects of serotonin (5-HT) and okadaic acid (OA) on the inhibitory junction of the crayfish opener muscle. Instead of using action potentials, we used 20 msec pulses depolarized to 0 mV to activate transmitter release. This approach allowed us to monitor two separate physiological parameters related to the release process. The first parameter, transmitter release kinetics, is characterized as the delay when inhibitory postsynaptic conductance reaches its half-maximum (IPSG50). The second parameter, the total area of IPSG (IPSGarea), estimates total transmitter output. We have reported previously that the F2 component of synaptic facilitation is associated with a decrease in IPSG50 but without a change in IPSGarea. These results raised the possibility that IPSG50 and IPSGarea could be mediated by separate mechanisms that were modulated independently. To explore this possibility, we investigated the effects of 5-HT (100-200 nM) and OA (2.5 microM) on the two parameters. 5-HT and OA enhanced IPSG neither by changing the sensitivity of postsynaptic receptors, as tested by iontophoretically ejected GABA, nor by elevating resting and action potential-activated presynaptic free calcium, as monitored by fura-2 imaging. 5-HT and OA decreased IPSG50 by 3.0 +/- 1.4 and 3.6 +/- 1.1 msec, respectively, and increased IPSGarea by 50 +/- 21 and 37 +/- 6%, respectively. The ability of F2 facilitation to accelerate release kinetics was reduced in the presence of the modulators, suggesting that the mechanism underlying the accelerated release kinetics was shared by the two modes of synaptic enhancement. This report demonstrates that the acceleration in release kinetics and the increase in total release are two separate mechanisms for enhancing transmitter output and that these two mechanisms can be activated without changes in presynaptic calcium dynamics.

Animals↗
PubMed1998

Effects of replacing extracellular chloride with formate on the inhibitory neuromuscular junction of the crayfish opener muscle.

The effect of partially replacing extracellular chloride by formate on the inhibitory junction of the crayfish opener muscle is investigated. Inhibitory postsynaptic potential (IPSP) amplitude, recorded in muscle fibers and presynaptic axons, increases significantly in the formate saline whereas input resistance and resting membrane potential of muscle fibers are not affected. The increase in IPSP amplitude is mainly due to an increase in IPSP driving force while the GABA mediated conductance change underlying IPSP is not altered. The waveform of presynaptic action potential is slightly altered by formate substitution where an after-depolarizing potential is decreased. This change does not seem to affect the probability of transmitter release because the magnitude of synaptic facilitation is unchanged. In conclusion, formate substitution significantly increases IPSP amplitudes by increasing its driving force without affecting presynaptic release mechanisms.

Animals↗
PubMed1998

Characteristic analysis of the luxG gene encoding the probable flavin reductase that resides in the lux operon of Photobacterium leiognathi.

Nucleotide sequence of the luxG gene (GenBank Accession No. AF053227) from Photobacterium leiognathi PL741 has been determined, and the encoded probable flavin reductase is deduced. The probable flavin reductase encoded by the luxG gene has a calculated M(r) 26,544 and comprises 235 amino acid residues. The probable flavin reductase like the NAD(P)H-flavin reductase might catalyze the reduction of flavins. Alignment and comparison of the probable flavin reductases from P. leiognathi PL741, ATCC 25521, P. phosphoreum, Vibrio fischeri, and V. harveyi show that they are homologous; there is 66% homologous (29.4% identity and 36.6% similarity). Also, the probable flavin reductase is homologous to the NAD(P)H-flavin reductase; it is perceived that the probable flavin reductase and the NAD(P)H-flavin reductase could be enzyme isoforms encoded by two genes of a multigene family for differential response functions. Functional analysis illustrates that the specific segment sequence lay inside and behind the luxG gene might form the potential hairpin loops omega gI, omega gII, omega o, and omega oT as mRNA stability loop or/and as the attenuator-like loop or the dynamic terminator-like block for sub-regulation in the lux operon. The gene order of the luxG gene in the lux operon and the lum operon is <--ter-lumQ-lumP-R&R-luxC-luxD-luxA-luxB-+ ++luxN-luxE-luxG--> (R&R: regulatory region; ter: transcriptional terminator), whereas the R&R is the regulatory region for the lum operon and the lux operon, and ter is the transcriptional terminator for the lum operon.

Amino Acid Sequence↗
PubMed1998

Characteristics analysis of the luzA gene encoding chaperone from Photobacterium leiognathi related to bioluminescence.

Nucleotide sequence of the luzA gene (GenBank accession No. AF039303) from Photobacterium leiognathi ATCC 25521 (NCIMB 2193) has been determined, and the chaperone encoded by the luzA gene was deduced. The LuzA chaperone has a calculated M(r) 26,295 and comprises 230 amino acid residues; the hydrophobic alpha-helix N-terminal 21 amino acid residues MKKTIFALLFMSVFI SYPSFA is the leader peptide, therefore the matured LuzA chaperone has a calculated M(r) 23,871 and comprises 209 amino acid residues only. The periplasmic LuzA chaperone is the protein concerned with the protein folding, assembly and stability. The luzA gene and the related genes are closely linked to the sod gene, that encoding Cu/Zn superoxide dismutase enables to enhance bioluminescence of the lux operon; the gene order of the luzA gene and related genes is -ufo'-luzA-ufoI-ufoII-ter->-R&R'-sod-ufo-- >. In trans complementation bioluminoassays in vivo elicit that the LuzA chaperone might be not directly concerned with bioluminescence of the lux operon from P. leiognathi in E. coli, but might enable to stabilize the proteins related to bioluminescence. The unidentified ufoII gene closely linked to the luzA gene is able to enhance bioluminescence.

Amino Acid Sequence↗
PubMed1998

Yotiao, a novel protein of neuromuscular junction and brain that interacts with specific splice variants of NMDA receptor subunit NR1.

The molecular machinery underlying neurotransmitter receptor immobilization at postsynaptic sites is poorly understood. The NMDA receptor subunit NR1 can form clusters in heterologous cells via a mechanism dependent on the alternatively spliced C1 exon cassette in its intracellular C-terminal tail, suggesting a functional interaction between NR1 and the cytoskeleton. The yeast two-hybrid screen was used here to identify yotiao, a novel coiled coil protein that interacts with NR1 in a C1 exon-dependent manner. Yotiao mRNA (11 kb) is present modestly in brain and abundantly in skeletal muscle and pancreas. On Western blots, yotiao appears as an approximately 230 kDa band that is present in cerebral cortex, hippocampus, and cerebellum. Biochemical studies reveal that yotiao fractionates with cytoskeleton-associated proteins and with the postsynaptic density. With regard to immunohistochemistry, two anti-yotiao antibodies display a somatodendritic staining pattern similar to each other and to the staining pattern of NR1. Yotiao was colocalized by double-label immunocytochemistry with NR1 in rat brain and could be coimmunoprecipitated with NR1 from heterologous cells. Thus yotiao is an NR1-binding protein potentially involved in cytoskeletal attachment of NMDA receptors. Consistent with a general involvement in postsynaptic structure, yotiao was also found to be specifically concentrated at the neuromuscular junction in skeletal muscle.

A Kinase Anchor Proteins↗
PubMed1998

A whole-cell clamp study of dendrodendritic synaptic activities in mitral cells of turtle olfactory bulb slices.

A procedure for preparing slices from the turtle olfactory bulb is described in this report. Individual layers of the bulb could be identified in the slices which enabled visual identification of cell types. Mitral cells retained extensive dendritic arborizations in slices of typical thickness, 300-400 microm. The presence of extensive dendritic processes was consistent with the difficulties we encountered in our attempt to achieve adequate space clamp. On the few occasions where an adequate space clamp of a mitral cell was achieved, calcium current exhibited a threshold of - 50 mV and reached its maximal level at - 10 mV. In all cases where calcium current was analysed (n=46), the current exhibited little inactivation. Depolarizing steps in 50% of the mitral cells triggered a burst of feedback synaptic activity after termination of the step. The intensity of feedback activity correlated closely with the amplitude of the depolarizing step, reaching its maximal level at - 10 mV and declining with further depolarization. The bell-shaped relationship between the feedback activity and mitral cell depolarization is consistent with the hypothesis that the feedback activity is mediated by reciprocal synapses on the mitral cell dendrite. This hypothesis is further supported by the inhibitory nature of the feedback synaptic activity: (i) the polarity of the feedback synaptic current could be inverted at the predicted chloride equilibrium potential, (ii) the feedback activity could be completely blocked by 10 microM bicuculline. The analysis of spontaneous synaptic activity showed that it was mostly inhibitory because its polarity could be reversed at the predicted chloride equilibrium potential. In some mitral cells, the frequency of spontaneous activity was noticeably increased when the holding potential was depolarized. This correlation could be attributed to the activation of dendrodendritic synapses. Results shown in this report demonstrate that dendrodendritic synapses are viable in turtle olfactory bulb slices. In addition, the suppression of feedback inhibition by large depolarizing steps of mitral cells suggests that the control of mitral cell dendritic potential is adequate to suppress calcium influx during large depolarizing steps.

Animals↗
PubMed1998

Thymic lymphoepithelioma-like carcinoma associated with thymoma in a patient with ocular myasthenia.

A 65-year-old woman with ocular myasthenia was found to have three tumours in the anterior mediastinum, revealed by magnetic resonance imaging. All three lesions were radically resected. Histologically, one was a mixed-type thymoma, one a thymic lymphoepithelioma-like carcinoma, and the third had features of both these types. This appears to be the first reported case of coexisting thymic lymphoepithelioma-like carcinoma (TLC) and thymoma associated with ocular myasthenia.

Aged↗
PubMed1998

Does cell type influence post-esophagectomy survival in patients with esophageal cancer?

The change in the prevalence of esophageal cancer by cell type from predominantly squamous cell carcinoma to adenocarcinoma has been well documented in the USA, UK, and Western Europe. The objective of this study was to determine if this shift in cell type resulted in a change in survival in patients treated by esophagectomy without neoadjuvant therapy. Our study group included 106 consecutive esophageal cancer patients who underwent esophagectomy without neoadjuvant therapy. Cell type was adenocarcinoma in 76, and squamous cell in 30 patients. For stage 1 tumors there was a trend towards survival advantage for patients with adenocarcinoma, but this did not reach significance. For stage 2-4 tumors and overall, there was no statistical difference in survival as a function of cell type. Therefore, the observed shift in cell type to a higher prevalence of adenocarcinoma does not alter expected post-surgical outcome.

Adenocarcinoma↗