Biomedical subjects

J W Lin

Publications and source records attributed to J W Lin.

At least 55 records · Page 3Linked to original sources

PubMed1998

Bronchial atresia associated with epibronchial right pulmonary artery and aberrant right middle lobe artery.

We report a case of bronchial atresia associated with an epibronchial right pulmonary artery (ERPA) and an aberrant right middle lobe artery (ARMLA). CT showed a branching opacity, which was hyperintense on MR images, in the anterior segment of the right upper lobe with segmental hyperinflation and the ERPA. At surgery, the ARMLA was found to originate from the ERPA, crossing the anterior aspect of the right upper lobe bronchus. It is postulated that the ARMLA might have interfered with the normal bronchial development, leading to the development of segmental bronchial atresia.

Abnormalities, Multiple↗

PubMed1998

Primary synovial sarcoma of the gastrocolic ligament.

A case of primary synovial sarcoma of the gastrocolic ligament is reported in a 37-year-old woman. CT showed an encapsulated intraabdominal cystic tumour with an amorphous solid component. Barium studies showed a mass at the gastrocolic ligament which elevated the gastric antrum and displaced the transverse colon downwards. This is the first report of synovial sarcoma formation in the gastrocolic ligament. This tumour may have originated from pluripotential mesenchyme.

Adult↗

PubMed1998

Congenital Ewing's sarcoma of the humerus.

We report an extremely rare case of Ewing's sarcoma (ES) of the humerus in a Chinese neonate. Plain radiography and magnetic resonance imaging showed extensive neoplastic involvement of the humeral diaphysis and adjacent soft tissues, confirmed on histology and immunohistochemistry as being due to ES. This is the first report of congenital ES in a long bone. Since ultrasound at 20 weeks gestation showed a normal fetal skeleton, the ES may have begun to develop in the late middle or third trimester.

Bone Neoplasms↗

PubMed1998

Thoracic neurilemomas: an analysis of computed tomography findings in 36 patients.

On computed tomography (CT), neurilemomas have generically been described as well-defined, round masses with heterogeneous contrast enhancement. The CT scans of 38 surgically proven thoracic neurilemomas in 36 patients were reviewed to characterize further the CT features of this tumor, with an emphasis on different enhancement patterns. Unenhanced CT was available in 32 patients; 10 tumors appeared isodense, and 22 tumors appeared slightly hypodense compared with chest wall muscle. Except for an intraosseous neurilemoma of the T8 vertebral body, which mimicked bone metastasis, the tumors could be categorized into five different patterns on CT after contrast enhancement. Twenty tumors (54.1%) revealed diffuse, but amorphous and inhomogeneous enhancement. Seventeen (45.9%) tumors appeared as masses with multiple hypodense or cystic areas. Of these 17, the pattern was somewhat radial enhancement (n = 6, 16.2%), peripheral enhancement with a large central hypodense area (n = 5, 13.5%), homogeneous hypodensity (n = 5, 13.5%), and central enhancement with peripheral hypodensity (n = l, 2.7%). Appreciation of various CT manifestations is important in the diagnosis of this tumor.

Adult↗

PubMed1997

Transcriptional analysis of the threonine dehydrogenase gene of Xanthomonas campestris.

The nucleotide sequence has previously been determined for the Xanthomonas campestris pv. campestris gene coding for threonine dehydrogenase (tdh). Flanking this gene are the upstream region possessing promoter activity and the downstream perfect inverted repeat having potential to form a stem-loop structure which resembles a transcription terminator. In addition, Northern blot analysis suggested the transcript of this gene to be monocistronic. In the present study, the essential region for promoter activity was narrowed down to a stretch of 57 bp which still retained 84% of the promoter activity. The first nucleotide to be transcribed is the guanosine at 30 nt upstream from the proposed tdh start codon. The putative terminator exhibited transcriptional termination activity bidirectionally in both Escherichia coli and X. campestris. These observations indicate that the transcriptional structure of X. campestris tdh is different from that of E. coli where tdh and kbl are organized into the tdh operon. Furthermore, the expression of tdh in X. campestris is repressed by leucine, a situation different from that in E. coli where leucine induces the expression of tdh operon.

Alcohol Oxidoreductases↗

PubMed1997

The pkI gene encoding pyruvate kinase I links to the luxZ gene which enhances bioluminescence of the lux operon from Photobacterium leiognathi.

Partial 3'-end nucleotide sequence of the pkI gene (GenBank accession No. AF019143) from Photobacterium leiognathi ATCC 25521 has been determined, and the encoded pyruvate kinase I is deduced. Pyruvate kinase I is the key enzyme of glycolysis, which converts phosphoenol pyruvate to pyruvate. Alignment and comparison of pyruvate kinase Is from P. leiognathi, E. coli and Salmonella typhimurium show that they are homologous. Nucleotide sequence reveals that the pkI gene is linked to the luxZ gene that enhances bioluminescence of the lux operon from P. leiognathi. The gene order of the pkI and luxZ genes is-pk1-ter-->-R&R"-luxZ-ter"-->, whereas ter is transcriptional terminator for the pkI and related genes, and R&R" is the regulatory region and ter" is transcriptional terminator for the luxZ gene. It clearly elicits that the pkI gene and luxZ gene are divided to two operons. Functional analysis confirms that the potential hairpin loop omega T is the transcriptional terminator for the pkI and related genes. It infers that the pkI and related genes are simply linked to the luxZ gene in P. leiognathi genome.

Amino Acid Sequence↗

PubMed1997

Molecular characterization of the gene coding for threonine dehydrogenase in Xanthomonas campestris.

The Xanthomonas campestris pv. campestris 17 gene tdh, which codes for the threonine dehydrogenase (TDH), was cloned and sequenced. The deduced gene product, a polypeptide consisting of 340 amino acids (Mr = 37,048), has 63.5% identity to the E. coli TDH in amino acid sequence and shares residue conservation with the alcohol/polyol dehydrogenases from different organisms. TDH activity was not detectable in the tdh mutant constructed by gene replacement; however, the enzyme activity in the mutant complemented in trans by a plasmid containing the complete tdh sequence was increased by 15 folds over Xc17. Northern blot analysis detected an mRNA with a size similar to that of the Xc17 tdh coding region, suggesting that the tdh gene-containing transcript may be monocistronic.

Alcohol Oxidoreductases↗

PubMed1997

Sequence analysis of the small cryptic Xanthomonas campestris pv. vesicatoria plasmid pXV64 encoding a Rep protein similar to gene II protein of phage 12-2.

The complete nucleotide sequence (1,851 bp) was determined for the Xanthomonas campestris pv. vesicatoria plasmid pXV64. Sequence analysis revealed an intergenic region (IG) of 355 bp and two oppositely running open reading frames, ORF1 and ORF2, encoding polypeptides of 39 and 16 kDa, respectively. While the function of ORF2 is not known, ORF1 is suggested to be the gene encoding Rep protein based on (i) similarity in amino acid sequence to that of the gene II protein (gIIP) of filamentous phage 12-2, (ii) presence of a sequence in the ori-containing region which is similar to the sequence around the Rep nicking site in some rolling circle-replicating replicons, and (iii) ability to support replication in trans of the region containing pXV64 ori (392 bp) which is located within the region including IG and a short stretch in the N-terminus of ORF2.

Amino Acid Sequence↗

PubMed1997

MR imaging of thoracic neurilemmomas.

Magnetic resonance (MR) imaging features of 15 thoracic neurilemmomas were analyzed. Morphologically, five tumor patterns could be identified on MR imaging including: inhomogeneous masses (n = 8), thick-walled multiloculated masses (n = 2), thick-walled central cystic masses (n = 2), homogeneous cystic masses (n = 2) and a target pattern mass (n = 1). The signal characterization of thoracic neurilemmomas was variable, usually brighter on T2-weighted images, hyper- to hypo-intense on T1-weighted images and always enhancing. Histopathologically, the inhomogeneous masses were characterized by irregular distribution of hypercellular Antoni A and hypocellular Antoni B tissues with variable degrees of cystic, hemorrhagic, myxoid and hyaline degenerative changes. Enlargement of the cystic areas led to the development of thick-walled multiloculated masses while confluence of these cystic areas produced a central cystic pattern. Extensive myxoid or hyaline degeneration yielded homogeneous cystic tumors. Peripheral fibrinous changes and central Antoni B stroma contributed to a target pattern. Appreciation of the protean MR manifestations and understanding of the underlying histopathological changes of thoracic neurilemmomas are helpful in the diagnosis of this tumor.

Adult↗

PubMed1997

Study of the inhibitor of the crayfish neuromuscular junction by presynaptic voltage control.

The inhibitor of the crayfish opener muscle was investigated by a presynaptic voltage control method. Two microelectrodes were inserted into the inhibitor and the amplitude and duration of presynaptic depolarization were controlled by a voltage-clamp amplifier. The inhibitory postsynaptic potential (IPSP) was measured from a muscle fiber located near the presynaptic voltage electrode. Nonlinear summation of IPSP amplitudes was corrected after chloride equilibrium potential was measured. With the use of 5-ms presynaptic pulses, the depolarization-release coupling (D-R) curve constructed from IPSP peak amplitudes (IPSPcor) had a threshold of about -35 mV and reached its maximal level at -5 to -10 mV. Depolarization beyond the maximum led to a suppression of neurotransmitter release. When transmitter release during a presynaptic pulse was completely suppressed, IPSPs activated by tail current could be identified with an average synaptic delay of 2.5 ms. Transmitter secretion triggered by a calcium current activated during the 5-ms pulses (IPSPon) was also measured on the rising phase of an IPSP, at 2.5 ms after the end of the 5-ms pulses. D-R coupling plots measured from IPSPon exhibited a more pronounced suppression than that obtained from IPSPcor. The effect of presynaptic pulse duration on the level of transmitter release was analyzed. Transmitter release increased with increasing duration and was nearly saturated by 20-ms pulses depolarized to 0 mV. The following conditions were identified as necessary to obtain a consistent D-R curve with a clear suppression: 1) small animals, 3.8 cm head to tail, 2) 15 degrees C, 3) 40 mM tetraethylammonium and 1 mM 4-aminopyridine, 4) an extracellular calcium concentration of < or = 10 mM. In addition, a consistent correlation was found among the branching pattern of the inhibitor, the placement of the presynaptic electrode, and the characteristics of the D-R curves. An ideal presynaptic electrode configuration involved placing the voltage electrode in a secondary branch, approximately 100 microns from the main branch point, and placing the current electrode at the branch point. Postsynaptically, optimal recordings were obtained from muscle fibers innervated by a single branch of the inhibitor that originated from a point near the presynaptic voltage electrode. A cable-release model was constructed to evaluate the relationship between the shape of the D-R coupling curves and the space constants of the presynaptic terminals. A comparison between the model and the D-R coupling curves suggested that the space constant of an inhibitor branch on a muscle fiber is > or = 8 times longer than its actual length. Therefore the upper limit estimate of the space constant of a typical preparation is approximately 3 mm. Results reported here outline morphological and physiological conditions needed to achieve optimal control of the presynaptic branch of the crayfish inhibitor. The cable-release model quantitatively defines the extent of presynaptic voltage control.

Animals↗

PubMed1997

Activation and detection of facilitation as studied by presynaptic voltage control at the inhibitor of the crayfish opener muscle.

Facilitation at the crayfish neuromuscular inhibitor synapse was investigated with the use of a presynaptic voltage control method in which 5-ms presynaptic pulses were used to activate and monitor facilitation. A single 5-ms pulse was able to activate facilitation with a decay time constant similar to that of the F2 component of facilitation activated by action potentials. The quality of the control of presynaptic potential during F2 facilitation was evaluated by measuring the amplitude of presynaptic pulses and by analyzing the shape of the depolarization-release coupling plot during facilitation. Both approaches suggested that neither the amplitude of presynaptic depolarizations nor the space clamp of the presynaptic axon was changed during F2 facilitation. The activation of facilitation was examined by changing the amplitude of conditioning pulses systematically and using a test pulse of a constant amplitude to monitor facilitation. We found that a significant amount of facilitation could be activated by conditioning pulses that were subthreshold to the activation of transmitter release. Facilitation plateaued before the inhibitory postsynaptic potentials (IPSPs) activated by conditioning pulses reached their maximum. A double logarithm plot of facilitation magnitude against the conditioning IPSP amplitude yielded a slope of 0.34, which implies that the calcium ion cooperativity of activating facilitation is about one third of the secretion process. These findings enabled us to activate near maximal facilitation, by a burst of subthreshold conditioning pulses, without any conditioning transmitter release, and, therefore, to avoid complications associated with previous transmitter release. The detection of facilitation was examined by changing test pulse amplitude systematically to evaluate the ability of the test pulse to detect a constant level of facilitation. The magnitude of normalized facilitation decreased with increasing test pulse amplitude. The magnitude of absolute facilitation (the amplitude of the facilitated minus the control IPSP) increased with increasing test pulse amplitude. A double logarithm plot between facilitated and control IPSPs gave rise to a slope of 0.77, which suggests that the calcium cooperativity of transmitter release was decreased during facilitation.

Animals↗

PubMed1997

Change of transmitter release kinetics during facilitation revealed by prolonged test pulses at the inhibitor of the crayfish opener muscle.

A presynaptic voltage-control method was used to study synaptic facilitation at the inhibitory neuromuscular synapse of the crayfish opener muscle. The expression of the F2 component of facilitation, monitored 150 ms after a conditioning stimulus, was examined by systematically changing the duration of the presynaptic test pulse. (Test pulses in all experiments were depolarized to 0 mV.) Control and facilitated inhibitory postsynaptic potentials (IPSPs) exhibited identical time courses when test pulse duration was brief (approximately 2 ms). When the duration of the test pulse was increased beyond 2 ms, the transmitter release time course shifted to an earlier point in time during facilitation. Meanwhile, the increase in total transmitter release, measured from inhibitory postsynaptic conductance (IPSG) area (total release), became less pronounced with increasing duration of the test pulse. With a 20-ms test pulse, facilitation did not cause any detectable change in total release but the half-maximal point of the facilitated IPSG shifted by 3 ms (release shift). This change in release kinetics was not associated with a decrease in minimal synaptic delay. Furthermore, the relationship between total release and presynaptic pulse duration suggested that the transmitter release activated by a 20-ms pulse can be defined as a distinct component of continuous transmitter release (early component). The facilitation process accelerated the release kinetics of the early component but did not modify its total transmitter content. To test the hypothesis that the release shift is indeed mediated by the same mechanism that increases IPSP amplitude during facilitation, we investigated the correlation between the release shift and IPSP amplitude change. The two parameters were significantly correlated when the magnitude of facilitation was changed 1) during the decay of facilitation and 2) by varying the strength of the conditioning stimulus. The experimental approach reported here provides two new physiological parameters, release shift and total release, for the analysis of synaptic facilitation.

Animals↗

PubMed1997

IS element ISXC6 of Xanthomonas campestris pv. campestris.

An insertion sequence element, ISXC6, was isolated from Xanthomonas campestris pv. campestris 17 (Xc17). Sequence analysis showed that it is 1,500 bp long and has 20-bp perfect inverted repeat ends. Upon transposition, a direct repeat TAATTC was generated, flanking this IS. No significant homology was observed between this sequence and other sequences in database. Results of Southern hybridization showed that multiple copies of ISXC6 were present in 7 strains of Xanthomonas examined.

Amino Acid Sequence↗

PubMed1997

Intracranial meningioma with intratumoral hemorrhage.

Meningiomas associated with intracranial hemorrhage are rare. Clinical presentation is frequently sudden. We present two patients with intracranial meningioma and intratumoral hemorrhage. One patient suffered concomitant intracerebral hemorrhage, which resulted in a decreased level of consciousness and hemiparesis. There was no evidence of coagulopathy in either patient. The patients underwent surgery for evacuation of the hematoma and tumor excision resulting in good recovery of neurologic function. The pathology reports revealed meningiomas; one was a syncytial type and the other was angioblastic. We reviewed 22 cases of meningioma associated with intratumoral hemorrhage, including our own, and found that death occurred in 55% (12/22) of patients with hemorrhagic complications. In the computed tomography (CT) era, there were 13 patients; of these, seven (58%) had recovered, and five (38%) died. There were nine cases from the pre-CT era; of these, seven (78%) died, and none had a good recovery. Early diagnosis with definitive surgery can bring about a more favorable outcome.

Adult↗

PubMed1997

Vulvovaginal tuberculosis: a case report.

A rare case of vulvovaginal tuberculosis is reported. A 76-year-old woman presented with a painful ulcer at the posterior fourchette and lower vagina for 6 weeks. Direct biopsy for histologic examination revealed mycobacterial infection. Anti-tuberculosis treatment was effective for this patient. We suggest prompt biopsies for suspicious vulvar or vaginal lesions.

Aged↗

PubMed1996

Nucleotide sequence and functional analysis of the luxE gene encoding acyl-protein synthetase of the lux operon from Photobacterium leiognathi.

Nucleotide sequence of the luxE gene GenBank Accession No. U66407 from Photobacterium leiognathi PL741 has been determined, and the amino acid sequence of acyl-protein synthetase encoded by the luxE gene is deduced. Nucleotide sequence reveals that the luxE gene encodes acyl-protein synthetase, which is a component of the fatty acid reductase complex that is responsible for converting fatty acid to aldehyde as substrate in the luciferase-catalyzed bioluminescence reaction. The acyl-protein synthetase encoded by the luxE gene has a calculated M, 43,128 and comprises 373 amino acid residues. Alignment and comparison of acyl-protein synthetases from P. leiognathi, P. phosphoreum, Vibrio fischeri, V. harveyi and Xenorhabdus luminescens shows that they are homologous; there is 75.5% homologous (44.2% identity and 31.3% similarity) among these species. Functional analysis illustrates that the specific segment sequence lying before or in the luxE gene might from potential loops omega o omega e1, omega e2 as mRNA stability loop and/or for sub-regulation by alternative modulation in the lux operon. The gene order of the luxE gene in the lux and the lum operons is<--ter-lumQ-lumP-R&R-luxC-luxD-luxA-luxB -luxN-luxE-->(R&R: regulatory region; ter; transcriptional terminator), whereas the R&R is the regulatory region for the lum and the lux operons, and ter is the transcriptional terminator for the lum operon.

Acyltransferases↗

PubMed1996

Construction of a broad-host-range promoter-probing vector and cloning of promoter fragments of Xanthomonas campestris.

A broad-host-range promoter-probing vector, pMY3 (8.0 kb), was constructed for cloning of DNA fragments containing promoter sequences of Xanthomonas campestris pv. campestris. This vector (pMY3) consists of the RK2 replicon, promoterless luxAB genes, the thr attenuator to block the transcription of RNA into the luxAB region, and multiple cloning sites for cloning of the fragment carrying promoter sequences. The feasibility of using pMY3 as a promoter-probing vector in both E. coli and Xc17 was demonstrated by using the lac promoter of E. coli, and the amy promoter of X. campestris in Xc17. Among the 63 promoter-containing fragments cloned from Xc17, only 9 were able to express in E. coli. It appears that X. campestris can recognize most E. coli type promoters, but, E. coli can recognize only a small portion of the X. campestris type promoters.

Cloning, Molecular↗

PubMed1996

Regulatory region with putA gene of proline dehydrogenase that links to the lum and the lux operons in Photobacterium leiognathi.

Nucleotide sequence of regulatory region (R & R) with putA gene (EMBL Accession No. U39227) from Photobacterium leiognathi PL741 has been determined, and the putA gene encoded amino acid sequence of proline dehydrogenase is deduced. Alignment and comparison of proline dehydrogenase of P. leiognathi with the proline dehydrogenase domain in the PutA protein of Escherichia coli and Salmonella typhimurium show that they are homologous. Nucleotide sequence reveals that regulatory region with the putA gene is linked to the lum and lux operons in genome; the gene order is <--putA--R & R(I)<--ter-lumQ-lumP-R & R-luxC-luxD-luxA-luxB-luxE--> (R & R: regulatory region; ter:transcriptional terminator), whereas the R & R is the regulatory region for the lum and the lux operons, ter is the transcriptional terminator for the lum operon, and R & R(I) apparently is the regulatory region for the putA and related genes. Nucleotide sequence analysis illustrates the specific inverted repeat (SIR), cAMP-CRP consensus sequence, canonical -10/-35 promoter, putative operator and Shine-Dalgarno (SD) sequence on the regulatory region R & R(I) for the putA and related genes; it suggests that the putA and related genes are simply linked to the lum and the lux operons in genome, the regulatory region R & R(I) is independent for the putA and related genes.

Amino Acid Sequence↗