Regulation of AMPA receptor-mediated synaptic transmission by clathrin-dependent receptor internalization

Redistribution of postsynaptic AMPA- (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid-) subtype glutamate receptors may regulate synaptic strength at glutamatergic synapses, but the mediation of the redistribution is poorly understood. We show that AMPA receptors underwent clathrin-dependent endocytosis, which was accelerated by insulin in a GluR2 subunit-dependent manner. Insulin-stimulated endocytosis rapidly decreased AMPA receptor numbers in the plasma membrane, resulting in long-term depression (LTD) of AMPA receptor-mediated synaptic transmission in hippocampal CA1 neurons. Moreover, insulin-induced LTD and low-frequency stimulation-(LFS-) induced homosynaptic CA1 LTD were found to be mutually occlusive and were both blocked by inhibiting postsynaptic clathrin-mediated endocytosis. Thus, controlling postsynaptic receptor numbers through endocytosis may be an important mechanism underlying synaptic plasticity in the mammalian CNS.

A reusable and specific protein A-coated piezoelectric biosensor for flow injection immunoassay

A hydrophilic matrix of periodate-oxidized dextran was used as a double-sided linker to covalently immobilize Staphylococcus aureus protein A (SpA) molecules onto a poly-L-lysine-modified piezoelectric crystal surface to improve their stability, activity, and binding specificity with human immunoglobulin G (IgG) in flow injection assays. The prepared sensing crystals displayed best sensitivity and reusability at a flow rate of 140 microL/min. A human IgG concentration as low as 0.3 nM can be detected by this system. Up to 19 successive assay repetitions were achieved without significant loss of sensitivity using the same crystal. The analysis of adsorption kinetics indicates that such a preparation can greatly increase the amount of available active human IgG binding sites on immobilized SpA. Hardly any response arising from unspecific binding was detected. In addition, the sensing crystal prepared by this method was found to retain activity better than one prepared via direct deposition when stored in either wet or dry states. Finally, the prepared SpA-coated crystals were applied to the affinity immobilization of polyclonal goat anti-Schistosoma japonicum glutathione-S-transferase (GST) and were able to subsequently detect GST and its genetically engineered mutant either in a purified form or in the crude cell lysate.

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.

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.

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.

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.

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.

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.

Laparoscopic cholecystectomy as a "true" outpatient procedure: initial experience in 130 consecutive patients

Laparoscopic cholecystectomy has received nearly universal acceptance and is currently considered the "gold standard" for the treatment of cholelithiasis. Many centers have employed "short-stay" units or "23-hour admissions" for postoperative observation following laparoscopic cholecystectomy. The practice of early discharge as "true" outpatients following this procedure has not been well defined. A retrospective analysis of 130 consecutive patients undergoing laparoscopic cholecystectomy in an outpatient surgery unit was performed. A follow-up telephone survey was carried out of patients who successfully completed the procedure as outpatients. One hundred thirty patients underwent outpatient laparoscopic cholecystectomy. The patient population consisted of 78% women, with an age range of 17 to 76 years (mean age 47.1 years). Symptomatic gallstone disease was the indication for laparoscopic cholecystectomy in 92% of the patients. All patients underwent successful completion of laparoscopic cholecystectomy with no conversions to an open procedure. The mean length of operation was 75 +/- 23 minutes (range 25 to 147 minutes). The mean length of stay in the postanesthesia care unit (PACU) ranged from 95 to 460 minutes with a mean length of stay of 200 +/- 79 minutes. A total of eight patients (6.2%) were admitted to the hospital directly from the PACU in the immediate postoperative period. Six of these eight patients were discharged on the first postoperative day. Following discharge from the PACU, an additional six patients (4.6%) required hospital admission. Three of these six patients were discharged after a single day of hospitalization. Ninety-eight of 116 eligible patients were available for follow-up telephone evaluation. The outpatient experience was rated as good by 75.5% of the patients, fair by 22.5%, and poor by 2%. In retrospect, 20.4% of the patients stated that they would have preferred an inpatient to an outpatient procedure. Laparoscopic cholecystectomy can be performed as a true outpatient procedure with patients discharged to home within hours of completion of the procedure. Less than 10% of patients will fail this protocol and another 5% of the patients may require hospitalization after returning to their homes.

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.

CT features of calcifications in abdominal malignant fibrous histiocytoma

The purpose of this study was to describe the computed tomographic (CT) features of intralesional calcifications in abdominal malignant fibrous histiocytomas (MFH). Forty-three pathologically proven abdominal MFH with preoperative CT were retrospectively reviewed, of which seven tumors with intralesional calcifications were studied with pathohistologic correlation. All seven calcified abdominal MFH belonged to the storiform-pleomorphic subtype with peripherally located calcifications that appeared as either lumpy (three cases) or ringlike (four cases), which were due to the presence of variable amounts of osseous (six cases) and chondroid metaplasia (two cases). About 16% of abdominal MFH, especially the storiform-pleomorphic subtype, exhibited metaplastic calcifications which were characteristically located at the periphery of the tumor and appeared as either lumpy or ringlike on CT.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.