[Effects of low concentration carbon monoxide on human physiological function]

Human volunteers were exposed to various low concentrations of carbon monoxide (CO) in a closed cabin. The results showed that 35 mg/m3 of CO caused slight subjective symptoms and reduction in contrast vision, operating efficiency and T-wave of ECG. At 80 mg/m3 and 115 mg/m3 the above changes were more severe and a rise in hearing threshold level was observed. It demonstrated that an inhibitory effect on the CNS and heart were caused by low concentrations of CO. According to the absorption curves for human exposed to CO, it is suggested that the sense effect level and vision effect level for CO are 7% COHb, and the hearing effect level is 9% COHb.

[Study on the contact allergen in 720 patients with dermatitis and eczema]

In order to investigate the causative factors of dermatitis and eczema, patch test was performed using the GB7804-87 standard allergens in 720 patients with dermatitis and eczema. There were 376 patients reacted to one or more allergens. The total positive reaction rate was 52.2%. Positive reactions were most frequently with cobaltsulphate (118 cases, 16.4%), potassium dichromate (115 cases, 16.0%), nickelchloride (108 cases, 15.0%) mercuric chloride (106 cases, 14.7%), Beihai detergent powder (63 cases, 8.8%), and p-phenylene diamine (50 cases, 6.9%). The positive rate was above 1% in 18 allergens. This study shows that the standard screening allergens are valuable in the investigation of the aetiology of the dermatitis and eczema.

Neuropilin-2, a novel member of the neuropilin family, is a high affinity receptor for the semaphorins Sema E and Sema IV but not Sema III

Semaphorins are a large family of secreted and transmembrane proteins, several of which are implicated in repulsive axon guidance. Neuropilin (neuropilin-1) was recently identified as a receptor for Collapsin-1/Semaphorin III/D (Sema III). We report the identification of a related protein, neuropilin-2, whose mRNA is expressed by developing neurons in a pattern largely, though not completely, nonoverlapping with that of neuropilin-1. Unlike neuropilin-1, which binds with high affinity to the three structurally related semaphorins Sema III, Sema E, and Sema IV, neuropilin-2 shows high affinity binding only to Sema E and Sema IV, not Sema III. These results identify neuropilins as a family of receptors (or components of receptors) for at least one semaphorin subfamily. They also suggest that the specificity of action of different members of this subfamily may be determined by the complement of neuropilins expressed by responsive cells.

Neuropilin is a receptor for the axonal chemorepellent Semaphorin III

Extending axons in the developing nervous system are guided to their targets through the coordinate actions of attractive and repulsive guidance cues. The semaphorin family of guidance cues comprises several members that can function as diffusible axonal chemorepellents. To begin to elucidate the mechanisms that mediate the repulsive actions of Collapsin-1/Semaphorin III/D (Sema III), we searched for Sema III-binding proteins in embryonic rat sensory neurons by expression cloning. We report that Sema III binds with high affinity to the transmembrane protein neuropilin, and that antibodies to neuropilin block the ability of Sema III to repel sensory axons and to induce collapse of their growth cones. These results provide evidence that neuropilin is a receptor or a component of a receptor complex that mediates the effects of Sema III on these axons.

Cytokines and costimulatory molecules as genetic adjuvants

DNA vectors expressing an antigen derived from a pathogen or a cancerous cell have been shown, after inoculation into experimental animals, to trigger de novo synthesis of foreign proteins, which induce an immune response. This immune response can be modulated by coinoculation of vectors encoding either cytokines or costimulatory molecules. A variety of cytokines such as granulocyte/macrophage colony-stimulating factor (GM-CSF), IL-2, IL-4, IL-12 and IFN-gamma, as well as the costimulatory molecule B7.1, have been tested to date for their ability to amplify the immune response to genetic vaccines. Although the results obtained thus far clearly show that coadministration of vectors expressing immunomodulatory molecules, such as cytokines, may increase the efficacy of genetic vaccines, this approach is currently considered unsuitable for use in human patients due to the potential side effects of persistent cytokine expression.

[Microsatellite instability in nephroblastoma and its relationship to clinicopathological variables]

OBJECTIVE

To study the relationship between microsatellite instability (MSI) and clinicopathological variables in nephroblastoma.

METHODS

2 microsatellite repeat sequences AR (chromosome X), UT762(chromosome 21) were examined in normal and tumor pairs from 50 nephroblastoma patients by PCR and denatured polyacrylamide gel electrophoresis.

RESULTS

The MSI positive for AR and UT loci were 14/50 and 10/50 respectively in nephroblastoma. MSI positive for both AR and UT occurred in 2 cases. According to NTWS-III categorization, stage I & II belong to early stage and stage III & IV belong to late stage, the MSI for this series were 16/38 and 6/12 for early and late stages. According to the NWTI-II categorization, the MSI of this series for favorable and non-favorable histology were 71% and 33% respectively.

CONCLUSIONS

Analysis of MSI may have some significance in discriminating the malignant status of nephroblastoma.

Role of protein-protein interactions in the function of replication protein A (RPA): RPA modulates the activity of DNA polymerase alpha by multiple mechanisms

Replication Protein A (RPA) from human cells is a stable complex of 70-, 32-, and 14-kDa subunits that is required for multiple processes in DNA metabolism. RPA binds with high affinity to single-stranded DNA and interacts with multiple proteins, including proteins required for the initiation of SV40 DNA replication, DNA polymerase alpha and SV40 large T antigen. We have used a series of mutant derivatives of RPA to map the regions of RPA required for specific protein-protein interactions and have examined the roles of these interactions in DNA replication. T antigen, DNA polymerase alpha and the activation domain of VP16 all have overlapping sites of interaction in the N-terminal half (residues 1-327) of the 70-kDa subunit of RPA. In addition, the interaction site for DNA polymerase alpha is composed of two functionally distinct regions, one (residues 1- approximately 170) which stimulates polymerase activity and a second (residues approximately 170-327) which increases polymerase processivity. In the latter, both the direct protein-protein interaction and ssDNA-binding activities of RPA were needed for RPA to modulate polymerase processivity. We also found that SV40 T antigen inhibited the ability of RPA to increase processivity of DNA polymerase alpha, suggesting that this activity of RPA may be important for elongation but not during the initiation of DNA replication. DNA polymerase alpha, but not T antigen also interacted with the 32- and/or 14-kDa subunits of RPA, but these interactions did not seem to effect polymerase activity.

The effect of interferon-gamma on genetic immunization

The effect of co-inoculation of a plasmid vector expressing the rabies virus glycoprotein and an additional vector encoding mouse interferon (IFN)-gamma on the development of an antigen specific B and T helper cell response was tested upon intramuscular inoculation of mice. The effect of IFN-gamma was dependent on the promoter driving expression of the viral antigen. The immune responses to antigen-expressing vector carrying a viral promoter such as the SV40 early promoter or the major histocompatibility (MHC) class I promoter were reduced in presence of IFN-gamma while the B and T helper cell response to a vector expressing the antigen under the control of the MHC class II promoter was not affected by this cytokine.

[A four-box multi-function testing system of pharmacology reaction]

The organism position matrix method, a new method of testing pharmacology reaction is proposed. On the basis of the method, we have developed a four-box multi-function testing system which can test the spontaneous activity, analgesic effect, and learning and memory ability of 1 to 4 mice in three dimensions respectively. Four quantitative parameters, the total distance, the movement intensity, the vertical number and the jumping number are put forward to describe the spontaneous activity. The starting time of continuous jumping and the jumping number are used to describe the analgesic effect. The time from the electrical shock to escape onto a safety platform and the number of the electrical shock are used to describe the learning and memory ability. The system has the characteristics of good repeatability, high efficiency, quantitative and automatic control.

Expression of an Epstein-Barr-virus receptor and Epstein-Barr-virus-dependent transformation of human nasopharyngeal epithelial cells

The human herpes virus Epstein-Barr (EBV) is clearly associated with African Burkitt's lymphoma and the undifferentiated form of nasopharyngeal carcinoma (NPC). EBV has been implicated in other types of lymphoma, as well as in some human breast cancers. However, its route of entry into epithelial cells is incompletely understood. We report here evidence that there is no gene alteration in the SCR 1 and 2 exons of EBVR/CR2 in human embryonic nasopharyngeal epithelial (HENE) cells and NPC cells and that SCR 1 and 2 mRNA could be detected in HENE cells, different differentiated NPC cell lines and well-differentiated NPC biopsies. None of 15 cases of poorly differentiated NPC cryosections has SCR 1 and 2 mRNA. We also provide evidence that transformation of HENE cells results from exposure to infectious EBV and that transformation is dependent on the presence of phorbol ester. These data suggest that expression of SCR 1 and 2 of EBVR/CR2 may be associated with replication of EBV and support the notion of direct infection and transformation of human nasopharyngeal epithelial cells destined to evolve into the carcinoma by EBV through EBVR/CR2.

[mRNA expression of metastasis-suppressor gene nm23 in carcinoma of buccal mucosa. II. Quantitative reverse transcription PCR amplification]

The nm23 gene is a conspicuous metastasis-suppressor gene. The authors detected both nm23-H1 and nm23-H2 mRNA levels in 47 tissues samples of patients with carcinoma of buccal mucosa (CBM) by quantitative reverse transcription PCR amplification. The results showed that expression levels of both nm23-H1 and nm23-H2 mRNA varied in normal buccal mucosa, leukoplakia, adjacent nontumorous mucosa, submandibular gland, CBM and lymph nodes with or without metastasis. The nm23-H1 mRNA expression levels in CBM with lymph nodes metastases were lower than those in CBM without metastases (P < 0.05), while no significance of nm23-H2 mRNA expression levels was found between CBM with and CBM without metastasis (P > 0.05). The results were comparative to those of Northern blotting of the same cases. The authors concluded that, as also in the study of Northern blotting, the expression of nm23-H1 mRNA significantly correlated inversely with lymph node metastasis in CBM, while the expression of nm23-H2 mRNA not. Q-RT-PCR was a useful method to detect the mRNA levels of nm23 gene in buccal carcinoma.

Isolation of human complexes proficient in nucleotide excision repair

More than 20 polypeptides are required for the process of nucleotide excision repair (NER) in both human and yeast cells. This pathway of excision repair has most often been viewed as an ordered multi-step process involving steps of damage recognition, incision/excision and finally repair DNA synthesis. Here we present evidence for the existence of a complex of human NER proteins pre-assembled in the absence of damaged DNA. This multi-protein complex was initially isolated from HeLa cell extracts by affinity chromatography on a matrix containing the damage recognition protein XPA. Subsequent co-immunoprecipitation and gel filtration experiments demonstrated that a significant portion of the human NER proteins was present in the form of a high molecular weight complex and that these complexes, or repairosomes, were capable of performing all steps of NER in vitro . Consistent with studies indicating that DNA polymerasesdeltaandstraightepsiloncan both function in NER, these two polymerases are found in these repairosome complexes.

Identification of important amino acid residues of the Na+-Ca2+ exchanger inhibitory peptide, XIP

The Na+-Ca2+ exchanger plays an important role in cardiac contractility by moving Ca2+ across the plasma membrane during excitation-contraction coupling. A 20 amino acid peptide, XIP, synthesized to mimic a region of the exchanger, inhibits exchange activity. We identify here amino acid residues important for inhibitory function. Effects of modified peptides on Na+-Ca2+ exchange activity were determined. Exchange activity was assessed as 45Ca2+ uptake into Na+-loaded cardiac sarcolemmal vesicles. We find that the entire length of XIP is important for maximal potency, though the major inhibitory components are between residues 5 and 16. Basic and aromatic residues are most important for the inhibitory function of XIP. Substitutions of arginine 12 and arginine 14 with alanine or glutamine dramatically decrease the potency of XIP, suggesting that these residues play a key role in possible charge-charge interactions. Substitutions of other basic residues with alanines or glutamines had less effect on the potency of XIP. All aromatic residues participate in binding with the exchanger, probably via hydrophobic interactions as indicated by tryptophan fluorescence. A tyrosine is required at position 6 for maximal inhibition and phenylalanine 5 and tyrosine 8 can only be replaced by other aromatic residues. Tyrosine 10 and tyrosine 13 can be replaced with other bulky residues. A specific conformation of XIP, with structural constrains provided by all parts of the molecule, is required for optimal inhibitory function.

[Gas chromatographic analysis of fatty acids in phosphatidylglycerol from needles of two crosses of Chinese Fir]

This paper reports a method for determination of fatty acids in phosphatidylglycerol from needles of two crosses of Chinese Fir with different cold-resistance. Some simplifications and improvements for analytical method of DEAE CL-6B column chromatography and of silica thin layer chromatography were also discussed. After being extracted with chloroform and methanol, phosphatidylglycerol was isolated from the general lipid extract by using DEAE CL-6B IEC and Silica TLC. Quantitative analysis was conducted by gas chromatography on a DB-FFAP (30m x 0.32mm i.d.) column. The results showed that there was a difference in the ratio of fatty acid (18:1+18:2+18:3)/[16:0+16:1(3t)] between the two crosses of Chinese Fir with different cold-resistance, 1.12 for that with higher cold-resistance and 1.25 for that with lower cold-resistance. A special fatty acid 16:1(3t) was found in both of the two crosses.

Decreased paralysis and better motor coordination with microspinal versus PE10 intrathecal catheters in pain study rats

We compared the standard PE10 catheter to a smaller microspinal catheter for intrathecal (IT) catheterization in rats. The PE10 or microspinal catheter was implanted in the lumbar subarachnoid space through the atlantooccipital membrane in rats (21 each group). Surviving rats without paralysis were tested on a rota-rod treadmill for motor function on Postoperative Days (POD) 3-6. Different doses of IT butorphanol were injected to demonstrate the functionality of the catheters by measuring tail-flick antinociception. Methylene blue was injected IT immediately before the spinal necropsy in each rat to identify the catheter tip location. For PE10 and microspinal catheters, the immediate death rate after the catheter implantation was 4 of 21 and 3 of 21 (no significant difference); paralysis rate was 8 of 21 and 2 of 21 (P < 0.05), and motor coordination recovery on POD6 was 67% and 91% (P < 0.01), respectively. Rats in both groups showed a dose-dependent response to IT butorphanol. Intrathecal methylene blue stained the lumbar spinal cord but not the surrounding tissue in both groups. Therefore, the microspinal catheter is better than the PE10 for IT catheterization in rats because it causes less paralysis and provides faster recovery of motor function.

[Pharmacological study of cholagogic capsule]

Cholagogic capsule is mainly composed of Fiuctus Cardui, Mariae, Oleum Menthae Piperilae, Radix Currmae, olia taraxaci, Oleum Hyperici. It is shown that Cholagogic Capsule increase the rat's bile secretion significantly, but bile component is not influenced effectively, the retention jaundice models of which are created by ANIT isn't influenced effectively. It can reduce the mouse pinna swelling caused by dimethythenzene and depress the metatarsal swelling induced by carragenin, the antiinflammatory effect keeps for more than 4 h. It inhibits the contraction of gallbladder smooth musele of Guinea Pig caused by Ach. The results show that cholagogic Capsule increase bile secretion, antispasmodic and antiinflammatory effect. It is suggested the therapeutic effects of Cholagogic Capsule in sand-like calcul and acute chronic cholecystitis are related to the above pharmaological effects.

Regulation of cardiac Na(+)-Ca2+ exchanger by the endogenous XIP region

The cardiac sarcolemmal Na(+)-Ca2+ exchanger is modulated by intrinsic regulatory mechanisms. A large intracellular loop of the exchanger participates in the regulatory responses. We have proposed (Li, Z., D.A. Nicoll, A. Collins, D.W. Hilgemann, A.G. Filoteo, J.T. Penniston, J.N. Weiss, J.M. Tomich, and K.D. Philipson. 1991. J. Biol. Chem. 266:1014-1020) that a segment of the large intracellular loop, the endogenous XIP region, has an autoregulatory role in exchanger function. We now test this hypothesis by mutational analysis of the XIP region. Nine XIP-region mutants were expressed in Xenopus oocytes and all displayed altered regulatory properties. The major alteration was in a regulatory mechanism known as Na(+)-dependent inactivation. This inactivation is manifested as a partial decay in outward Na(+)-Ca2+ exchange current after application of Na+ to the intracellular surface of a giant excised patch. Two mutant phenotypes were observed. In group 1 mutants, inactivation was markedly accelerated; in group 2 mutants, inactivation was completely eliminated. All mutants had normal Na+ affinities. Regulation of the exchanger by nontransported, intracellular Ca2+ was also modified by the XIP-region mutations. Binding of Ca2+ to the intracellular loop activates exchange activity and also decreases Na(+)-dependent inactivation. XIP-region mutants were all still regulated by Ca2+. However, the apparent affinity of the group 1 mutants for regulatory Ca2+ was decreased. The responses of all mutant exchangers to Ca2+ application or removal were markedly accelerated. Na(+)-dependent inactivation and regulation by Ca2+ are interrelated and are not completely independent processes. We conclude that the endogenous XIP region is primarily involved in movement of the exchanger into and out of the Na(+)-induced inactivated state, but that the XIP region is also involved in regulation by Ca2+.

Age-related ischemia in the brain following bilateral carotid artery occlusion--collateral blood flow and brain metabolism

Cerebral blood flow (CBF) and cerebellar blood flow (CeBF) were measured and correlated with brain lactate, pyruvate and adenosine triphosphate concentrations from groups representing 3-week old suckling (n = 10), 18-22-week old adult (n = 9) and 70-week old aged (n = 7) Sprague-Dawley rats before and during bilateral carotid occlusion (BCO). The steal ratio, calculated as the ratio of %control CBF to %control CeBF, was 1.02 +/- 0.06 (mean +/- SEM) at 60 minutes of BCO in adult rats that exhibited normal levels of brain metabolites. By contrast, the ratios significantly decreased to 0.74 +/- 0.06 in suckling rats and 0.69 +/- 0.06 in aged rats with simultaneous increases by 2.4 to 2.9-fold of tissue lactate. Pyruvate and lactate/pyruvate ratio also increased by 1.4 to 1.8 times control in both suckling and aged rats. We conclude that there is age-related steal phenomenon occurring with blood flow during BCO. Ischemic derangement of the brain metabolism is in part related to poor blood supply from the posterior circulation in suckling and aged rats.

The human cytomegalovirus UL97 protein is a protein kinase that autophosphorylates on serines and threonines

The product of the human cytomegalovirus (CMV) UL97 gene, which controls ganciclovir phosphorylation in virus-infected cells, is homologous to known protein kinases but diverges from them at a number of positions that are functionally important. To investigate UL97, we raised an antibody against it and overexpressed it in baculovirus-infected insect cells. Recombinant baculovirus expressing full-length UL97 directed the phosphorylation of ganciclovir in insect cells, which was abolished by a four-codon deletion that confers ganciclovir resistance to CMV. When incubated with [gamma-32P]ATP, full-length UL97 was phosphorylated on serine and threonine residues. Phosphorylation was severely impaired by a point mutation that alters lysine-355 in a motif that aligns with subdomain II of protein kinases. However, phosphorylation was impaired much less severely by the four-codon deletion. A UL97 fusion protein expressed from recombinant baculovirus was purified to near homogeneity. It too was phosphorylated upon incubation with [gamma-32P]ATP in vitro. This phosphorylation, which was abolished by the lysine 355 mutation, was optimal at high NaCl and high pH. The activity required either Mn2+ or Mg2+, with a preference for Mn2+, and utilized either ATP or GTP as a phosphate donor, with Kms of 2 and 4 microM, respectively. The phosphorylation rate was first order with protein concentration, consistent with autophosphorylation. These data strongly argue that UL97 is a serine/threonine protein kinase that autophosphorylates and suggest that the four-codon deletion affects its substrate specificity.

Organic vapor sensors based on SAW resonator and organic films

The majority of investigations of SAW devices used as chemical sensors are based on delay line oscillators. However, SAW resonator oscillator offers some advantages over the SAW delay line oscillator for its higher stability. In the incipient stage of fabricating gas sensors based upon SAW resonator, taking detection of organic vapor as an example, the analysis method that combines the SAW theory with organic film technology has been adopted to give an intensive insight into the responses of two-port SAW resonator coated with LB-film and cast-film after exposure to organic vapors.

Identification of amino acid residues required for a specific interaction between Src-tyrosine kinase and proline-rich region of phosphatidylinositol-3' kinase

The binding of ligand to B-cell antigen receptors (BCR) leads to the activation of receptor-associated Src-family kinases and phosphatidylinositol-3' kinase (PI-3 kinase). Although it has been demonstrated that SH3 domains of several Src-family kinases interact with PI-3 kinase by binding to a proline-rich region of PI-3 kinase in vitro, there is no direct evidence to support their interaction in vivo. Thus, we utilized the yeast two-hybrid assay to reconstitute this protein-protein interaction. This genetic screen clearly indicates that the interaction between SH3 domain of Fyn and the proline-rich region (residues: 80-104) of PI-3 kinase is highly specific. Mutational analysis revealed that amino acid residues Asp92, Tyr93, Arg96 and Thr97 of the SH3 domain of Fyn are essential for interacting with the proline-rich peptide of PI-3 kinase.

Assessing the requirements for nucleotide excision repair proteins of Saccharomyces cerevisiae in an in vitro system

Nucleotide excision repair (NER) is the primary mechanism by which both Saccharomyces cerevisiae and human cells remove the DNA lesions caused by ultraviolet light and other mutagens. This complex process involves the coordinated actions of more than 20 polypeptides. To facilitate biochemical studies of NER in yeast, we have established a simple protocol for preparing whole cell extracts which perform NER in vitro. As expected, this assay of in vitro repair was dependent on the products of RAD genes such as RAD14, RAD4, and RAD2. Interestingly, it was also dependent upon proteins encoded by the RAD7, RAD16, and RAD23 genes whose precise roles in NER are uncertain, but not the RAD26 gene whose product is believed to participate in coupling NER to transcription. Replication protein A (RPA/Rpa), known to be required for NER in human cell extracts, was also shown by antibody inhibition and immunodepletion experiments to be required for NER in our yeast cell extracts. Moreover, yeast cells with temperature-sensitive mutations in the RFA2 gene, which encodes the 34-kDa subunit of Rpa, had increased sensitivity to UV and yielded extracts defective in NER in vitro. These data indicate that Rpa is an essential component of the NER machinery in S. cerevisiae as it is in mammalian cells.

Synchrony in binary-oscillator networks with local couplings

Since synchronous oscillations in the visual cortex may be responsible for some features of visual scene, many works have been done to study the dynamics of oscillatory neural networks. Most of the oscillator network models rely on a global connection to reach synchronization. Here we propose a class of neural network models based on a simplified binary-oscillator, and find that the neurons of networks with local couplings will be in global synchrony under some criteria.

Prediction of the secondary structure content of globular proteins based on structural classes

The prediction of the secondary structure content (alpha-helix and beta-strand content) of a globular protein may play an important complementary role in the prediction of the protein's structure. We propose a new prediction algorithm based on Chou's database [Chou (1995), Proteins Struct. Funct. Genet. 21, 319]. The new algorithm is an improved multiple linear regression method, taking the nonlinear and coupling terms of the frequencies of different amino acids into account. The prediction is also based on the structural classes of proteins. A resubstitution examination for the algorithm shows that the average errors are 0.040 and 0.033 for the prediction of alpha-helix content and beta-strand content, respectively. The examination of cross-validation, the jackknife analysis, shows that the average errors are 0.051 and 0.044 for the prediction of alpha-helix content and beta-strand content, respectively. Both examinations indicate the self-consistency and the extrapolative effectiveness of the new algorithm. Compared with the other methods available currently, our method has the merits of simplicity and convenience for use, as well as a high prediction accuracy. By incorporating the prediction of the structural classes, the only input of our method is the amino acid composition of the protein to be predicted.