Observation of an exotic S = +1 baryon in exclusive photoproduction from the deuteron

In an exclusive measurement of the reaction gammad-->K(+)K(-)pn, a narrow peak that can be attributed to an exotic baryon with strangeness S=+1 is seen in the K(+)n invariant mass spectrum. The peak is at 1.542+/-0.005 GeV/c(2) with a measured width of 0.021 GeV/c(2) FWHM, which is largely determined by experimental mass resolution. The statistical significance of the peak is (5.2+/-0.6)sigma. The mass and width of the observed peak are consistent with recent reports of a narrow S=+1 baryon by other experimental groups.

Measurement of the proton spin structure function g1(x,Q2) for Q2 from 0.15 to 1.6 GeV2 with CLAS

Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g(1)(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q(2)=0.15-1.64 GeV2. The contributions to the first moment Gamma(1)(Q2)= integral g(1)(x,Q2) dx were determined up to Q(2)=1.2 GeV2. Using a parametrization for g(1) in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in Gamma(1) is observed for Q2<1 GeV2, with a sign change near Q(2)=0.3 GeV2, indicating dominant contributions from the resonance region. At Q(2)=1.2 GeV2 our data are below the perturbative QCD evolved scaling value.

Measurement of ep-->e' ppi+ pi- and baryon resonance analysis

The cross section for the reaction ep-->e(')ppi(+)pi(-) was measured in the resonance region for 1.4<W<2.1 GeV and 0.5<Q2<1.5 GeV(2)/c(2) using the CLAS detector at Jefferson Laboratory. The data show resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on N(*) and Delta states shows an evident discrepancy. A better description of the data is obtained either by a sizable change of the properties of the P13(1720) resonance or by introducing a new baryon state, not reported in published analyses.

First measurement of transferred polarization in the exclusive ep-->e'K+Lambda--> reaction

The first measurements of the transferred polarization for the exclusive e-->p-->e(')K+Lambda--> reaction have been performed at Jefferson Laboratory using the CLAS spectrometer. A 2.567 GeV beam was used to measure the hyperon polarization over Q2 from 0.3 to 1.5 (GeV/c)(2), W from 1.6 to 2.15 GeV, and over the full K+ center-of-mass angular range. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A nonrelativistic quark-model interpretation of our data suggests that the ssmacr; quark pair is produced with spins predominantly antialigned. Implications for the validity of the most widely used quark-pair creation operator are discussed.

Photoproduction of the omega meson on the proton at large momentum transfer

The differential cross section, dsigma/dt, for omega meson exclusive photoproduction on the proton above the resonance region (2.6<W<2.9 GeV) was measured up to a momentum transfer -t=5 GeV2 using the CLAS detector at Jefferson Laboratory. The omega channel was identified by detecting a proton and pi(+) in the final state and using the missing mass technique. While the low momentum transfer region shows the typical diffractive pattern expected from Pomeron and Reggeon exchange, at large -t the differential cross section has a flat behavior. This feature can be explained by introducing quark interchange processes in addition to the QCD-inspired two-gluon exchange.

Influence of co-substrates on structure of microbial aggregates in long-chain fatty acid-fed anaerobic digesters

AIMS

The purpose of this study was to investigate the influence of co-substrates, such as glucose and cysteine, on the structure of microbial aggregates in anaerobic digesters treating oleate, a long-chain fatty acid (LCFA).

METHODS AND RESULTS

Transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM) were used to examine the structure of microbial aggregates. Fluorescence in situ hybridization (FISH) techniques were also used to characterize and localize the different trophic groups present in the aggregates. Oleate was found to inhibit the methanogenic activity and formation of granular biomass in digesters. The addition of co-substrates, such as glucose and cysteine either singly or in combination, increased the methanogenic activity and formation of granular biomass. Glucose was more effective than cysteine in reducing the inhibition by oleate on the methanogenic bacteria and in enhancing the formation of granules.

CONCLUSIONS

The addition of nutrient substrate, such as glucose and cysteine could decrease the toxicity of LCFA on anaerobic granulation.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results suggest that the addition of other substrates might decrease the toxicity of LCFA on the granulation of biomass in anaerobic digesters and enhance methanogenic activity. A combination of TEM, CLSM and FISH techniques provides a better tool for visualizing microbial aggregates and for differentiating and localizing different microbial groups within these aggregates.

Eta photoproduction on the proton for photon energies from 0.75 to 1.95 GeV

Differential cross sections for gammap-->etap have been measured with tagged real photons for incident photon energies from 0.75 to 1.95 GeV. Mesons were identified by missing mass reconstruction using kinematical information for protons scattered in the production process. The data provide the first extensive angular distribution measurements for the process above W=1.75 GeV. Comparison with preliminary results from a constituent quark model support the suggestion that a third S11 resonance with mass approximately 1.8 GeV couples to the etaN channel.

Q2 Dependence of quadrupole strength in the gamma*p --> Delta(+)(1232) --> p pi(0) transition

Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role.

First measurement of the double spin asymmetry in (-->)e(-->)p-->e(prime)pi(+)n in the resonance region

The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.

Targeted disruption of the murine Fanconi anemia gene, Fancg/Xrcc9

Fanconi anemia (FA) is a human autosomal recessive cancer susceptibility disorder characterized by cellular sensitivity to mitomycin C and ionizing radiation. Six FA genes (corresponding to subtypes A, C, D2, E, F, and G) have been cloned, and the encoded FA proteins interact in a common cellular pathway. To further understand the in vivo role of one of these human genes (FANCG), we generated a targeted disruption of murine Fancg and bred mice homozygous for the targeted allele. Similar to the phenotype of the previously described Fancc(-/-) and Fanca(-/-) mice, the Fancg(-/-) mice had normal viability and no gross developmental abnormalities. Primary splenic lymphocytes, bone marrow progenitor cells, and murine embryo fibroblasts from the Fancg(-/-) mice demonstrated spontaneous chromosome breakage and increased sensitivity to mitomycin C and, to a lesser extent, ionizing radiation. Fancg(-/-) lymphocytes had a defect in the FA pathway, based on their failure to activate the monoubiquitination of the downstream Fancd2 protein in response to IR. Finally, Fancg(-/-) mice had decreased fertility and abnormal gonadal histology. In conclusion, disruption of the Fancg gene confirms the role of Fancg in the FA pathway. The Fancg(-/-) mouse may be useful as an animal model for future gene therapy and cancer susceptibility studies.

Rich dynamics of a ratio-dependent one-prey two-predators model

The objective of this paper is to systematically study the qualitative properties of a ratio-dependent one-prey two-predator model. We show that the dynamics outcome of the interactions are very sensitive to parameter values and initial data. Specifically, we show the interactions can lead to all the following possible outcomes: 1). competitive exclusion; 2). total extinction, i.e., collapse of the whole system; 3). coexistence in the form of positive steady state; 4). coexistence in the form of oscillatory solutions; and 5). introducing a friendly and better competitor can save a otherwise doomed prey species. These results reveal far richer dynamics compared to similar prey dependent models. Biological implications of these results are discussed.

[Historical and herbalogical studies on coloring crude drug (Part 1): "Langbacao"]

The name of Langbacao was described for the first time in Kai Bao Ben Cao in 10th century, in which Langbacao was introduced as an herb medicine for scours. While, as the name of Qu, Wujie, it was first described in Er Ya and as the name of Langyecao, it was first described in Ben Cao Shi Yi. Many investigators have confirmed that the original plant of Langbacao is to be Bidens tripartita L. In Japan, Langbacao is generally recognized as ta-u-ko-gi, while some investigators suggested that it is unlikely that ta-u-ko-gi is identical to Langbacao. In the old Chinese literature, Langbacao had been mentioned as a dye which could make hair dark. But in modern Chinese and Japanese literature, few papers reported the use of Bidens tripartita L. as a dye. The characteristics of the shapes of Langbacao between old and modern literature seem not to be consistent. Other names of Langbacao are confused even in the modern literature. It seems that Langbacao in the old literature includes species of the genus Bidens other than B. tripartita.

Photoproduction of the rho(0) meson on the proton at large momentum transfer

The differential cross section, d sigma/dt, for rho(0) meson photoproduction on the proton above the resonance region was measured up to a momentum transfer -t = 5 GeV2 using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The rho(0) channel was extracted from the measured two charged-pion cross sections by fitting the pi(+)pi(-) and p pi(+) invariant masses. The low momentum transfer region shows the typical diffractive pattern expected from Reggeon exchange. The flatter behavior at large -t cannot be explained solely in terms of QCD-inspired two-gluon exchange models. The data indicate that other processes, like quark interchange, are important to fully describe rho photoproduction.

Moderate hypothermia therapy for patients with severe head injury

OBJECTIVE

To evaluate the effect and safety of early moderate hypothermia therapy (MHT) on patients with head injury by using parallel-control test.

METHODS

Thirty patients with severe head injury within 6 hours after accidents were treated by MHT generally for 4-10 days. The other 30 patients with similar head injury treated routinely were enrolled for a parallel-control test. The mortality, morbidity and changes of some neuro-functional indexes as Glasgow Coma Scores, and Glasgow Outcome Scale, levels of endothelin and some other factors of neurobiochemistry in blood plasma were observed. Meanwhile, the dynamic monitoring by transcranial Doppler ultrasonography was conducted in these patients.

RESULTS

The mortality in MHT group was significantly lower than that in control group. MHT not only reduced endothelin but also increased the brain biochemical factors, which were helpful to the protection of neurons in the early brain ischemia after head injury.

CONCLUSIONS

Early MHT can help reduce mortality and morbidity in patients with acute head injury.

High concentrations of adrenergic antagonists prolong sciatic nerve blockade by tetrodotoxin

BACKGROUND

Millimolar-range concentrations of some adrenergic antagonists have been shown to have local anesthetic-like properties, and to stimulate GTPase activity in vitro. In this report, we investigate whether these agents can potentiate the effect of tetrodotoxin (TTX) and bupivacaine, a conventional local anesthetic, and whether GTPase activation plays a role.

METHODS

Rats received sciatic nerve blockade with tetrodotoxin or bupivacaine co-injected with adrenergic antagonists and/or agonists, or pertussis toxin. Thermal nociceptive blockade was quantified with modified hotplate testing.

RESULTS

Nerve block from TTX alone lasted 153 (99-223) min (median and 25th and 75th percentiles). Co-injection with 20 mM phentolamine, propranolol, and yohimbine prolonged TTX block to 856 (765-862), 486 (444-510), and 465 (413-495) min respectively (P<0.005 in all cases, compared to TTX alone). Micromolar concentrations of adrenergic antagonists (which inhibited the prolongation of TTX block by epinephrine) did not prolong TTX block. Injection of adrenergic antagonists alone did not produce specific nerve block. They did not prolong TTX block when injected at a remote subcutaneous site. Prolongation of TTX block by phentolamine was not inhibited by co-injection with pertussis toxin. Adrenergic antagonists did not prolong bupivacaine block.

CONCLUSIONS

High concentrations of adrenergic antagonists markedly prolonged TTX block, but not bupivacaine block. This locally mediated action does not appear to be adrenergic-receptor-specific, or mediated by GTPase activation.

Functional analysis of patient-derived mutations in the Fanconi anemia gene, FANCG/XRCC9

OBJECTIVE

Fanconi anemia (FA) is an autosomal-recessive cancer susceptibility syndrome with seven complementation groups. Six of the FA genes have been cloned (corresponding to subtypes A, C, D2, E, F, and G) and the encoded proteins interact in a common pathway. Patient-derived mutations in FA genes have been helpful in delineating functional domains of FA proteins. The purpose of this work was to subtype FA patient-derived cell lines in our repository and to identify FA gene mutations.

METHODS

We subtyped 62 FA patients as type A, G, C, or non-ACG by using a combination of retroviral gene transfer and immunoblot analysis. Among these FA patients, we identified six FA-G patients for further analysis. We used a strategy involving amplification of FANCG/XRCC9 exons and direct sequencing to identify novel FANCG mutations in cell lines derived from these FA-G patients. We functionally analyzed FANCG mutant alleles by transducing the corresponding cDNAs into a known FA-G indicator cell line and scoring correction of MMC sensitivity.

RESULTS

Our results demonstrate a wide range of mutations in the FANCG gene (splice, nonsense, and missense mutations). Based on this mutational screen, a carboxy terminal functional domain of the FANCG protein appears to be required for complementation of FA-G cells and for normal assembly of the FANCA/FANCG/FANCC protein complex.

CONCLUSION

The identification of patient-derived mutant alleles of FA genes can provide important insights to the function of FA proteins. FA subtyping is also a necessary precondition for gene therapy.

[The diagnosis and treatment of quadrilateral space syndrome]

OBJECTIVE

To investigate the compression feature, clinical manifestation and the results of treatment of quadrilateral space syndrome.

METHODS

Four patients with axillary nerve entrapment at quadrilateral space had been treated and followed up for 5 to 12 months from May 1999 to June 2000. The causes, symptoms, signs and the treatment management of those cases were analyzed.

RESULTS

Among the 3 cases which received operation, sensation and motor function completely recovered in 2 cases and partially recovered in 1 case. No obvious recovery of sensation and motor function in the case which received local nerve blocking treatment.

CONCLUSION

The main diagnostic evidence for axillary nerve entrapment is the deltoid muscle paralysis and paresthesia in the lateral side of shoulder, and early neurolysis is recommended as soon as the diagnosis is clarified.

Global analysis of the Michaelis-Menten-type ratio-dependent predator-prey system

The recent broad interest on ratio-dependent based predator functional response calls for detailed qualitative study on ratio-dependent predator-prey differential systems. A first such attempt is documented in the recent work of Kuang and Beretta(1998), where Michaelis-Menten-type ratio-dependent model is studied systematically. Their paper, while contains many new and significant results, is far from complete in answering the many subtle mathematical questions on the global qualitative behavior of solutions of the model. Indeed, many of such important open questions are mentioned in the discussion section of their paper. Through a simple change of variable, we transform the Michaelis-Menten-type ratio-dependent model to a better studied Gause-type predator-prey system. As a result, we can obtain a complete classification of the asymptotic behavior of the solutions of the Michaelis-Menten-type ratio-dependent model. In some cases we can determine how the outcomes depend on the initial conditions. In particular, open questions on the global stability of all equilibria in various cases and the uniqueness of limit cycles are resolved. Biological implications of our results are also presented.

[Molecular characterization of glucose-6-phosphate dehydrogenase deficiency in the Han and Li nationalities in Hainan, China and identification of a new mutation in human G6PD gene]

OBJECTIVE

To elucidate the molecular basis of G6PD deficiency in the Han and Li nationalities in Hainan, China.

METHODS

Polymerase chain reaction and restriction enzyme digestion were used to screen the mutations 1388G-->A, 1360C-->T, 1024C-->T, 592C-->T, 517T-->C, 493A-->G, 487G-->A, 392G-->T and 95A-->G. Single strand conformation polymorphism analysis was used to screen the other mutations followed by DNA sequencing to characterize the mutations of the samples with abnormal SSCP bands.

RESULTS

Of the fifty-nine Han cases with G6PD deficiency, fourteen with 1388G-->A (23.7%), three with 871G-->A(5.1%), one with 835A-->T(1.7%), one with 517T-->C (1.7%), three with 392G-->T(5.1%), and four with 95A-->G(6.8%) were found. Of the thirty-two Li cases with G6PD deficiency, six with 1388G-->A(18.8%), three with 871G-->A(9.4%), and two with 95A-->G(6.3%) were found. A new mutation 835A-->G which causes the substitution of Ala for Thr at 279 in a Han case was identified and named as G6PD Haikou. The enzyme activity of the variant is about 10% of the normal and lower than the activity of the variant 835A-->T with about 40% of the normal. Analysis of the 3D model of human G6PD has revealed that the hydroxyl group of Thr at 279 is a group in maintaining the interaction of the G6PD subunits.

CONCLUSION

The most common mutations of G6PD deficiency in Han and Li nationalities in Hainan are similar. Compared with the mutation spectrum of G6PD gene in the populations in other regions of China, the results indicate that some G6PD gene mutations are widespread in the populations of different regions in the southern part of China. The hydroxyl group of the Thr at 279 of human G6PD may be a necessary group for maintaining the interaction of the G6PD subunits and the enzyme activity.

The ep -->e'p eta reaction at and above the S11(1535) baryon resonance

New cross sections for the reaction e p-->e p eta are reported for total center of mass energy W = 1.5--1.86 GeV and invariant momentum transfer Q2 = 0.25--1.5 (GeV/c)(2). This large kinematic range allows extraction of important new information about response functions, photocouplings, and eta N coupling strengths of baryon resonances. Newly observed structure at W approximately 1.65 GeV is shown to come from interference between S and P waves and can be interpreted with known resonances. Improved values are derived for the photon coupling amplitude for the S11(1535) resonance.

Changes in systemic and splanchnic hemodynamics after orthotopic liver transplantation in cirrhotic rats

OBJECTIVE

To investigate early changes in systemic and splanchnic hemodynamics after orthotopic liver transplantation (OLT) in normal and cirrhotic rats.

METHODS

Male Sprague-Dawley rats were divided into 4 groups: normal controls (NL, n = 10), intrahepatic portal hypertension (IHPH, n = 10) induced by injection of CCl4, normal rats with OLT (NL-OLT, n = 9) and IHPH rats with OLT (IHPH-OLT, n = 16). IHPH-OLT rats were divided into 2 subgroups: 3 days (Group A, n = 9) and 7 days (Group B, n = 7) after OLT. OLT was performed in rats using cuffs for the anastomosis of the suprahepatic inferior vena cava, infrahepatic vena cava and portal vein. Two weeks after production of IHPH rats, 7 days after NL-OLT rats, 3 days and 7 days after IHPH-OLT rats, radioactive microspheres were used in a hemodynamic study.

RESULTS

There were no significant differences in hemodynamic changes between NL-OLT and NL rats, except mean arterial blood pressure (MAP). The characteristics of systemic and splanchnic hyperdynamic circulatory state, including increased cardiac output and splanchnic blood flow, decreased mean arterial blood pressure, total peripheral vascular resistance and splanchnic vascular resistance were observed in IHPH, IHPH-OLT A, and IHPH-OLT B rats. The magnitude of hyperhemodynamics was in the order of IHPH > IHPH-OLT A > IHPH-OLT B rats. Moreover, the derangement of splanchnic hyperhemodynamics was more significant than that of systemic hyperthermodynamics.

CONCLUSIONS

The present study demonstrates that the persistence of early systemic and splanchnic hyperkinetic circulation after OLT may be the consequence of factors which maintain hyperhemodynamics in liver cirrhosis, where portal hypertension is not completely eliminated. Hyperhemodynamics is not induced by OLT per se.

The fanconi anemia proteins FANCA and FANCG stabilize each other and promote the nuclear accumulation of the Fanconi anemia complex

Fanconi anemia (FA) is an autosomal recessive cancer susceptibility syndrome with 8 complementation groups. Four of the FA genes have been cloned, and at least 3 of the encoded proteins, FANCA, FANCC, and FANCG/XRCC9, interact in a multisubunit protein complex. The FANCG protein binds directly to the amino terminal nuclear localization sequence (NLS) of FANCA, suggesting that FANCG plays a role in regulating FANCA nuclear accumulation. In the current study the functional consequences of FANCG/FANCA binding were examined. Correction of an FA-G cell line with the FANCG complementary DNA (cDNA) resulted in FANCA/FANCG binding, prolongation of the cellular half-life of FANCA, and an increase in the nuclear accumulation of the FA protein complex. Similar results were obtained upon correction of an FA-A cell line, with a reciprocal increase in the half-life of FANCG. Patient-derived mutant forms of FANCA, containing an intact NLS sequence but point mutations in the carboxy-terminal leucine zipper region, bound FANCG in the cytoplasm. The mutant forms failed to translocate to the nucleus of transduced cells, thereby suggesting a model of coordinated binding and nuclear translocation. These results demonstrate that the FANCA/FANCG interaction is required to maintain the cellular levels of both proteins. Moreover, at least one function of FANCG and FANCA is to regulate the nuclear accumulation of the FA protein complex. Failure to accumulate the nuclear FA protein complex results in the characteristic spectrum of clinical and cellular abnormalities observed in FA.

Stoichiometry in producer-grazer systems: linking energy flow with element cycling

All organisms are composed of multiple chemical elements such as carbon, nitrogen and phosphorus. While energy flow and element cycling are two fundamental and unifying principles in ecosystem theory, population models usually ignore the latter. Such models implicitly assume chemical homogeneity of all trophic levels by concentrating on a single constituent, generally an equivalent of energy. In this paper, we examine ramifications of an explicit assumption that both producer and grazer are composed of two essential elements: carbon and phosphorous. Using stoichiometric principles, we construct a two-dimensional Lotka-Volterra type model that incorporates chemical heterogeneity of the first two trophic levels of a food chain. The analysis shows that indirect competition between two populations for phosphorus can shift predator-prey interactions from a (+, -) type to an unusual (-, -) class. This leads to complex dynamics with multiple positive equilibria, where bistability and deterministic extinction of the grazer are possible. We derive simple graphical tests for the local stability of all equilibria and show that system dynamics are confined to a bounded region. Numerical simulations supported by qualitative analysis reveal that Rosenzweig's paradox of enrichment holds only in the part of the phase plane where the grazer is energy limited; a new phenomenon, the paradox of energy enrichment, arises in the other part, where the grazer is phosphorus limited. A bifurcation diagram shows that energy enrichment of producer-grazer systems differs radically from nutrient enrichment. Hence, expressing producer-grazer interactions in stoichiometrically realistic terms reveals qualitatively new dynamical behavior.

A new cembranolide from the soft coral Sinularia capillosa

A new cembranolide, capillolide (1), and three known cembranolides were isolated from the soft coral Sinularia capillosa collected from the South China Sea. Their structures and the relative stereochemistry of 1 were deduced on the basis of spectroscopic methods.

Immune responses in rats following oral immunization with attenuated Salmonella typhimurium expressing human sperm antigen

The HSD-I gene codes a human sperm membrane protein (hSMP-1) and has been assigned the accession number U12978. The gene is located on human chromosome 9, region p12-p13. When the 1.7-kb cDNA of HSD-I was digested sequentially with EcoRI, BamHI, and HindIII, a 550-bp cDNA fragment was formed, which codes for the extracellular domain. This fragment was cloned into the asd+ vector pYA3149 to construct pYA3149R. The recombinant plasmid was used to transform an avirulent deltacva, deltacrp, deltaasd vaccine strain of Salmonella typhimurium chi4550. The hSMP-1 component was localized on the surface of the head of mature rat spermatozoa by an immunofluorescence technique using polyclonal anti-hSMP-1 antibodies. Since rat sperm contain hSMP-1, this rodent can be used to assay the immunogenicity of pYA3149R. Female Wistar rats were immunized by oral administration of the recombinant Salmonella. Anti-hSMP-1 antibodies in blood and vaginal washes of immunized animals were determined. Both body fluids contained significant amounts of the antibodies, showing that the recombinant Salmonella is an effective oral immunogen in rats.

1376G-->T mutation of G6PD gene in Han and Li nationalities in Hainan, China

OBJECTIVE

To investigate the 1376G-->T mutation of G6PD gene in the cases of G6PD deficiency in the Han nationality and the Li nationality of Hainan, China.

METHODS

DNAs were extracted from the white blood cells of G6PD deficient cases by salt-out method. Allelic specific polymerase chain reaction was used to detect the 1376G-->T mutation.

RESULTS

Fifty-nine Han nationality cases and 32 Li nationality cases were analysed; the 1376G-->T mutation was found in 19 Han cases(32.2%) and 18 Li cases(56.2%).

CONCLUSION

1376G-->T is a common mutation which causes G6PD deficiency in the Han nationality and the Li nationality in Hainan, China. Based on the phylogenetic tree of populations in China, these results indicate that the mutation might occur prior to the divergence of the Han and Li nationalities. It is of significance to study the mutations of G6PD gene in different nationalities in China for elucidating the origin, migration and evolution of the nationalities.

Carboxy terminal region of the Fanconi anemia protein, FANCG/XRCC9, is required for functional activity

Fanconi anemia (FA) is an autosomal recessive cancer susceptibility syndrome with eight complementation groups. Four of the FA genes have been cloned, and at least three of the encoded proteins, FANCA, FANCC, and FANCG/XRCC9, interact in a nuclear complex, required for the maintenance of normal chromosome stability. In the current study, mutant forms of the FANCA and FANCG proteins have been generated and analyzed with respect to protein complex formation, nuclear translocation, and functional activity. The results demonstrate that the amino terminal two-thirds of FANCG (FANCG amino acids 1-428) binds to the amino terminal nuclear localization signal (NLS) of the FANCA protein. On the basis of 2-hybrid analysis, the FANCA/FANCG binding is a direct protein-protein interaction. Interestingly, a truncated mutant form of the FANCG protein, lacking the carboxy terminus, binds in a complex with FANCA and translocates to the nucleus; however, this mutant protein fails to bind to FANCC and fails to correct the mitomycin C sensitivity of an FA-G cell line. Taken together, these results demonstrate that binding of FANCG to the amino terminal FANCA NLS sequence is necessary but not sufficient for the functional activity of FANCG. Additional amino acid sequences at the carboxy terminus of FANCG are required for the binding of FANCC in the complex. (Blood. 2000;96:1625-1632)

[Effects of ischemic preconditioning on apoptosis of hepatocytes in liver transplantation in rats]

OBJECTIVE

To evaluate the effects of ischemic preconditioning (IP) on hepatocyte apoptosis in ischemia/reperfusion injury of grafted liver and clarify its mechanism.

METHODS

Orthotopic liver transplantation with cuff anastomosing method for the portal vein, suprahepatic vena cava and infrahepatic vena cava in the rats were divided into two groups: with and without IP treatment. The parameters of liver function were determined by auto-biochemical analyser. The concentrations of malondialdehyde (MDA) were measured with chromometry. The apoptotic hepatocytes in grafts liver were detected by flow cytometry combined with the in situ terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick end-labeling (TUNEL) method.

RESULTS

The levels of AST, ALT, LDH in the serum, and MDA and apoptotic cells in the liver were significantly increased compared with normal values after ischemia/reperfusion to the grafted liver. After IP treatment, the levels of AST, ALT, LDH, MDA and apoptotic cells were significantly decreased.

CONCLUSION

IP can attenuate ischemia/reperfusion injury by alleviating lipid peroxide and decreasing apoptosis of hepatocytes.

An analysis of two polymorphic points of the 7th intron of human p53 gene

OBJECTIVE

To detect polymorphic points of the 7th intron of human p53 oncogene.

METHODS

Polymerase chain reaction (PCR) and double- strand DNA direct sequencing were used to analyse sequence alteration of p53 intron 7. One hundred and five cases of normal human peripheral blood samples with no genetic relation were investigated.

RESULTS

There were two polymorphic points in the 7th intron of p53 gene. The first one was localized at 73 base pair (bp) to 3'-end of exon 7; the other one at 93. Three genotypes were found. Twenty-two cases were of type TG, 37 cases were of type CT, and the other 46 cases were of heterozygote. Because the first point was alteration of GGGCCC to GGGTCC or its heterozygote, it had a point alteration of enzyme Apa I.

CONCLUSION

There are two polymorphic points in the 7th intron of human p53 gene, which may be of importance to identification of individual genetic relation and to judging of a case in forensic medicine.

Improved branching ratio measurement for the decay K(0)(L) --> &mgr;(+)&mgr;(-)

We report results from Experiment 871, performed at the BNL AGS, of a measurement of the branching ratio K(0)(L)-->&mgr;(+)&mgr;(-) with respect to the CP-violating mode K(0)(L)-->pi(+)pi(-). This experiment detected over 6200 candidate &mgr;(+)&mgr;(-) events, a factor of 6 more than that seen in all previous measurements combined. The resulting branching ratio gamma(K(0)(L)-->&mgr;(+)&mgr;(-))/gamma(K(0)(L)-->pi(+)pi(-)) = (3. 474+/-0.057)x10(-6) leads to a branching fraction B(K(0)(L)-->&mgr;(+)&mgr;(-)) = (7.18+/-0.17)x10(-9), which is consistent with the current world average, and reduces the uncertainty in this decay mode by a factor of 3.

The local anesthetic properties and toxicity of saxitonin homologues for rat sciatic nerve block in vivo

BACKGROUND AND OBJECTIVES

Saxitoxin and its homologues are naturally occurring compounds that block the sodium channel with high potency. They have the potential for providing prolonged duration local anesthesia when coinjected with vasoconstrictors or conventional local anesthetics and are devoid of local neurotoxicity. Here, we compare sciatic nerve block with saxitoxin to those with neosaxitoxin, decarbamoyl saxitoxin, and tetrodotoxin (TTX), in a search for even safer compounds.

METHODS

Rats received percutaneous sciatic nerve block with toxins. The compounds were compared in terms of lethality, onset and duration of action for thermal analgesia (hot-plate testing), and motor block (weight-bearing). Data were expressed as medians with 25th and 75th percentiles, and median effective concentrations were determined.

RESULTS

The median concentrations at which analgesia of 60 minutes duration was achieved were neosaxitoxin, 34+/-2 micromol/L; saxitoxin, 58+/-3 micromol/L; TTX, 92+/-5 micromol/L; and decarbamoyl saxitoxin, 268+/-8 micromol/L. Similar trends were observed for other measures of effectiveness (block duration of 90 minutes, maximal block), and for lethality so that the therapeutic indices were similar. No toxin had a marked predominance of sensory or motor block. The potency of TTX was intermediate between those of the saxitoxins, and its therapeutic index was slightly better. No difference was observed in time to onset of nerve blockade among the toxins.

CONCLUSIONS

Substitutions on the saxitoxin nucleus result in large differences in incidence and duration of block, and toxicity. The therapeutic indices of the saxitoxins are similar; that of TTX is slightly better.

[Clinical study of metastasis of thoracic lymph node in resectable lung cancer]

OBJECTIVE

To study the metastatic pattern of thoracic lymph node in resectable lung cancer.

METHODS

From January 1992 to July 1998, the lymph nodes in hilar(N1) and mediastinal(N2) were resected based on their distribution in 160 patiens with resectable lung cancer and were examined by pathology. Number, size and colour of lymph nodes in each regions were recorded. Each lymph node was examined by routine pathology and immunohistochemistry. Quantity of metastatic lymph node was reported according to their regions.

RESULTS

99 cases(61.9%) had thoracic lymph nodes metastasis and 73 cases (45.6%) had mediastinal lymph nodes metastasis. Of those, only N1 metastasis was 16.3%, from N1 to N2 metastasis was 32.5%, only N2 metastasis was 13.1%. The metastatic frequencies in 11, 10, 7, 5 and 4 regions around the hilar or root of lung were 30.0%, 27.5%, 16.9%, 28.8% and 20.0%, respectively. Those were higher than 9, 6, 3, 2 and 1 regions far from the root of lung. The metastatic rate of lymph node in 2.0 cm or greater, 1.0 cm or greater and less than 1.0 cm was 60.7%, 15.5% and 4.3%, respectively (P < 0.001). The smallest metastatic lymph node was only 0.2 cm x 0.2 cm. Statistical analysis revealed that metastatic rate of thoracic lymph nodes was not relevant to different area, size and course of tumors.

CONCLUSIONS

The lymph nodes metastases of most cases were spreading from the near to the distant, from lower to upper, through the hilar to the mediastinal. Lymph nodes metastases occurred easier in SCLC than in NSCLC (P < 0.05). It must be depended on pathologic examination to confirm whether or not the tumor has metastasis to lymph node.

[Cytological diagnosis of Hashimoto's hyperthyroidism]

OBJECTIVE

To assess the value of thyroid fine needle biopsy (FNB) in Hashimoto's hyperthyroidism.

METHODS

FNB for was performed 58 (5 males and 53 females, aged from 13 to 66 years) of 1 031 patients who was performed clinically dignosised as having hyperthyroidism according to clinic symptoms, the results of physical and, laboratory examination, especially the increased the serum circle antibody and lowered sTSH during March 1995 to February 1998. Their smears were classified into 4 types according to the degree of degeneration of adenoidal cell and lymphocyte invasion.

RESULTS

Hyperthyroidism was observed in 5 cases, I type in 9, II type in 9, III type in 4, and IV type in 31 (53%).

CONCLUSIONS

FNB is helpful in diagnosis of hyperthyroidism.

Fanconi anemia proteins FANCA, FANCC, and FANCG/XRCC9 interact in a functional nuclear complex

Fanconi anemia (FA) is an autosomal recessive cancer susceptibility syndrome with at least eight complementation groups (A to H). Three FA genes, corresponding to complementation groups A, C, and G, have been cloned, but their cellular function remains unknown. We have previously demonstrated that the FANCA and FANCC proteins interact and form a nuclear complex in normal cells, suggesting that the proteins cooperate in a nuclear function. In this report, we demonstrate that the recently cloned FANCG/XRCC9 protein is required for binding of the FANCA and FANCC proteins. Moreover, the FANCG protein is a component of a nuclear protein complex containing FANCA and FANCC. The amino-terminal region of the FANCA protein is required for FANCG binding, FANCC binding, nuclear localization, and functional activity of the complex. Our results demonstrate that the three cloned FA proteins cooperate in a large multisubunit complex. Disruption of this complex results in the specific cellular and clinical phenotype common to most FA complementation groups.

Effects of nitric oxide inhibitor on prostacyclin biosynthesis in portal hypertensive rats

OBJECTIVE

To evaluate the effects of nitric oxide inhibitor on prostacyclin (PGI2) biosynthesis and the role of PGI2 in hyperhemodynamics of portal hypertension.

METHODS

Sprague Dawley rats were divided into four groups: intrahepatic portal hypertension (IHPH) by injection of CCl4, prehepatic portal hypertension (PHPH) by stenosis of the portal vein, end-to-side portacaval shunt (PCS), and sham-operated controls (SO). Animals of each group were subdivided into 2 groups: systemic administration of nitric oxide inhibitor L-NMMA and vehicle. The radioactive microsphere method was used for hemodynamic study. The level of plasma PGI2 (6-keto-PGF1 alpha) was measured by radioimmunoassay.

RESULTS

The characteristics of hyperdynamic circulatory state including increased cardiac output and splanchnic blood flow, decreased mean arterial blood pressure, total peripheral vascular resistance, and splanchnic vascular resistance were observed in IHPH, PHPH and PCS rats. The magnitude of hyperhemodynamics was in the order of PCS > PHPH > IHPH rats. The hyperdynamic circulatory state in IHPH, PHPH and PCS rats could be effectively reversed by L-NMMA to the baseline values of hemodynamics in SO rats. The baseline concentrations of plasma 6-keto-PGF1 alpha (ng/ml) in PHPH, IHPH, PCS, and SO rats were 6.93 +/- 2.43, 5.09 +/- 2.27, 2.36 +/- 1.01 and 1.56 +/- 0.61, respectively. The concentrations of plasma 6-Keto-PGF1 alpha in PHPH, IHPH and PCS rats were significantly higher than those in SO rats. Moreover, the concentrations were significantly higher in PHPH and IHPH rats than in PCS rats (P < 0.05). After administration of L-NMMA, the concentrations of plasma 6-Keto-PGF1 alpha (ng/ml) in PHPH, IHPH, PCS and SO rats were 7.69 +/- 2.98, 5.68 +/- 2.66, 5.50 +/- 0.79, 5.02 +/- 2.86, respectively. As compared to the baseline value, the concentrations of 6-keto-PGF1 alpha rats were slightly increased in IHPH, PHPH rats (P > 0.05), but significantly increased in PCS and SO rats (P < 0.05).

CONCLUSIONS

In this study, the hyperdynamic circulatory state in portal hypertensive rats and portacaval shunt rats was completely reversed by L-NNMA to normal, but the level of 6-keto-PGF1 alpha was still elevated. The results indicate that PGI2 is not involved in hyperhemodynamics of portal hypertension.

Changes and challenges in China. Is the "open policy" closing doors in Chinese hospitals?

Since 1978, China's economic reforms and her pursuit of modern technology have significantly opened the scope of her hospital services and financing. While the decentralization and higher incomes have given Chinese hospitals new freedoms, they have also raised the specter of new limitations on access to healthcare. The authors review these changes and consider what the future holds for the Chinese hospital system.

The molecular and cellular biology of Fanconi anemia

Fanconi anemia is a rare autosomal recessive disease characterized by multiple congenital abnormalities, bone marrow failure, and cancer susceptibility. The mean age of onset of anemia is 8 years, and the mean survival is 16 years. Death usually results from complications of bone marrow failure. Considerable progress in Fanconi anemia research has resulted from the recent identification and cloning of three Fanconi anemia genes. The current review describes the structure and function of the Fanconi anemia genes and describes the role of the encoded Fanconi anemia proteins in a cellular pathway controlling chromosome stability.

Vanilloid receptor agonists potentiate the in vivo local anesthetic activity of percutaneously injected site 1 sodium channel blockers

BACKGROUND

Capsaicin, the pungent ingredient in chili peppers, is a vanilloid with noxious and analgesic effects that inhibits tetrodotoxin-resistant sodium currents. Because tetrodotoxin-resistant currents are found primarily in small-diameter nociceptor afferents of the peripheral nerves, their inhibition may lead to selective analgesia. Therefore, the authors evaluated the interactions between tetrodotoxin, a site 1 sodium channel blocker, and capsaicin on nerve blockade in vivo.

METHODS

Percutaneous sciatic nerve injections with 0 to 9.9 mM capsaicin, 0 to 120 microM tetrodotoxin, or both were administered to male Sprague-Dawley rats. Thermal nociceptive and motor blockade were measured. Data were expressed as medians with 25th and 75th percentiles.

RESULTS

Capsaicin produced a transient increase in thermal latency with no effect on motor strength. Tetrodotoxin reduced motor strength for a longer duration than nociception. The interaction between tetrodotoxin and capsaicin was synergistic, as evidenced by (1) supraadditive prolongation of both nociceptive and motor block, with the effect of capsaicin reversed by the vanilloid antagonist capsazepine, and (2) synergism in the frequency that rats achieved maximal block shown by isobolographic analysis. The combination of tetrodotoxin and capsaicin showed less motor predominance than tetrodotoxin did alone. Similar interactions were found between tetrodotoxin and resiniferatoxin (another vanilloid), and between capsaicin and saxitoxin (another site 1 sodium channel blocker), but much less so between bupivacaine and capsaicin.

CONCLUSIONS

Site 1 sodium channel blockers and vanilloids have synergistic effects on nerve blockade in vivo. These interactions may be useful in developing prolonged local anesthetics and elucidating mechanisms of functionally selective nerve blockade.

Boo, a novel negative regulator of cell death, interacts with Apaf-1

In this report, we describe the cloning and characterization of Boo, a novel anti-apoptotic member of the Bcl-2 family. The expression of Boo was highly restricted to the ovary and epididymis implicating it in the control of ovarian atresia and sperm maturation. Boo contains the conserved BH1 and BH2 domains, but lacks the BH3 motif. Like Bcl-2, Boo possesses a hydrophobic C-terminus and localizes to intracellular membranes. Boo also has an N-terminal region with strong homology to the BH4 domain found to be important for the function of some anti-apoptotic Bcl-2 homologues. Chromosomal localization analysis assigned Boo to murine chromosome 9 at band d9. Boo inhibits apoptosis, homodimerizes or heterodimerizes with some death-promoting and -suppressing Bcl-2 family members. More importantly, Boo interacts with Apaf-1 and forms a multimeric protein complex with Apaf-1 and caspase-9. Bak and Bik, two pro-apoptotic homologues disrupt the association of Boo and Apaf-1. Furthermore, Boo binds to three distinct regions of Apaf-1. These results demonstrate the evolutionarily conserved nature of the mechanisms of apoptosis. Like Ced-9, the mammalian homologues Boo and Bcl-xL interact with the human counterpart of Ced-4, Apaf-1, and thereby regulate apoptosis.

Mechanism of overproduction of plasma prostacyclin in portal hypertensive rats

OBJECTIVE

To evaluate the role of increased portal pressure and portosystemic shunting in elevated level of prostacyclin (PGI2) in portal hypertension.

METHODS

Thirty-six male Sprague-Dawley rats were divided into four groups: prehepatic portal hypertension (PHPH, 8 rats), intrahepatic portal hypertension (IHPH, 9), end-to-side portacaval shunt (PCS, 8), and sham-operated controls (SO, 11). Two weeks after surgery, free portal pressure (FPP) was measured; systemic and splanchnic hemodynamics was studied by radioactive microsphere technique and blood sample from the femoral artery was obtained to measure the level of plasma 6-keto-PGF1 alpha with radioimmunoassay.

RESULTS

The FPP (mmHg) in IHPH, PHPH, PCS and SO rats was 13.10 +/- 1.02, 12.10 +/- 1.52, 3.0 +/- 0.82 and 6.86 +/- 0.69, respectively. The value of FPP was significantly increased in IHPH, PHPH rats and significantly decreased in PCS rats when compared to SO rats. Cardiac index (CI) and portal venous inflow (PVI) were in the order of PCS > PHPH > IHPH > SO rats. Portosystemic shunting (PSS) in PCS, PHPH, IHPH was 99.7 +/- 0.29%, 76.02 +/- 20.62% and 30.34 +/- 10.18%, respectively. The concentrations of plasma 6-keto-PGF1 alpha (ng/ml) in PHPH, IHPH, PCS and SO rats were 6.93 +/- 2.43, 5.09 +/- 2.27, 2.36 +/- 1.01 and 1.56 +/- 0.61, respectively. The concentrations of plasma PGI2 in PHPH, IHPH and PCS rats were significantly higher than those in SO rats. Furthermore, the concentrations of plasma PGI2 in PHPH and IHPH rats were also significantly higher than those in PCS rats. Moreover, a closed positive correlation existed between plasma PGI2 and FPP (r = 0.67, P < 0.001).

CONCLUSIONS

The results of the present study suggest that the elevated PGI2 in portal hypertension is mainly due to the overproduction of PGI2 in vascular epithelium cells induced by increased portal pressure, whereas portosystemic shunting and liver dysfunction play a secondary role. In addition, the results of this study do not support that PGI2 mediated the hyperhemodynamics in portal hypertension.

[Interleukin-6 and its soluble receptors in human breast cancer]

OBJECTIVE

To study interleukin-6(IL-6) and its receptors in human breast cancer.

METHODS

Using ELISA method and ABC immunohistochemistry, IL-6 and its receptors were examined in 45 cases of breast cancer, 10 cases of benign breast diseases and 17 cases of healthy women.

RESULTS

High levels of serum IL-6 and its soluble receptors were frequently observed in breast cancer patients. The levels correlated with the stage and axillary lymph node involvement. The positive staining of IL-6, IL-6R alpha, gp130 were 68.9% in neoplasm tissue.

CONCLUSION

IL-6 and its soluble receptors may be important paramenters reflecting the biological behaviour and prognosis of breast cancer.

Modeling and analysis of a marine bacteriophage infection

A mathematical model for the marine bacteriophage infection is proposed and its essential mathematical features are analyzed. Since bacteriophage infection induces bacterial lysis which releases into the marine environment, on the average, 'b' viruses per cell, the parameter b epsilon (1, t infinity) or 'virus replication factor' is chosen as the main parameter on which the dynamics of the infection depends. We proved that a threshold b* exists beyond which the endemic equilibrium bifurcates from the free disease one. Still, for increasing b values the endemic equilibrium bifurcates toward a periodic solution. We proved that a compact attractor set omega within the positive cone exists and within omega the free disease equilibrium is globally stable whenever b < or = b*, whereas it becomes a strong uniform repeller for b > b*. A concluding discussion with numerical simulation is then presented.

[Experimental study of the effect on growth of Schwann cell from chitin and chitosan in vitro]

In order to study the effect of chitin and chitosan on the growth of Schwann cell (SC) of rats in vitro, the SC was isolated from sciatic nerve and brachial plexus of new-born rats. After the enzymatic and mechanical dissociation, the cell suspension was vaccinated on chitin membrane and chitosan fluid-coated glass coverslips. Then, the growth of SC was examined at 1, 3, 7 days after culture under light microscope and scanning electron microscope. The results showed that 94 percent of the cell grown from was SC and only 6% was fibroblast (FB), while that of the control SC 71% and FB 29% in population. The number of SC in chitosan suspension was more than that in chitin. Therefore, the conclusion was that the chitin and chitosan was histocompatible to SC, and chitosan suspension was superior to chitin, and both could inhibit the growth of fibroblast.

[The role of nitric oxide in hyperdynamic circulation in portal hypertensive rats]

OBJECTIVE

To evaluate the role of nitric oxide (NO) in hyper-hemodynamics in portal hypertension, we investigated the effects of nitric oxide synthase inhibitor L-NMMA with or without L-arginine, the substrate for enzyme NO synthase on the systemic and splanchnic hemodynamics in portal hypertensive rats.

METHOD

Ninety-seven male Sprague-Dawley rats were divided into four groups: intrahepatic portal hypertension (IHPH, n = 23) by injection of CCl4, prehepatic portal hypertension (PHPH, n = 26) by stenosis of the portal vein, end-to-side portacaval shunt (PCS, n = 23), and sham-operated controls (SO, n = 25). Animals of each group were divided into three subgroups: systemic administration of L-NMMA (50 mg/kg BW, 1 ml), L-NMMA (50 mg/kg BW, 0.5 ml) plus L-arginine (30 mg/kg BW, 0.5 ml), and normal saline solution (1 ml). The radioactive microsphere method was used for hemodynamic study.

RESULT

There was the characteristic of hyperdynamic circulatory state including increased cardiac output and splanchnic blood flow, decreased mean arterial blood pressure, total peripheral vascular resistance and splanchnic vascular resistance in IHPH, PHPH and PCS rats. The hyperdynamic circulatory state in IHPH, PHPH and PCS rats could be effectively reversed by L-NMMA to the resting values of hemodynamics in SO rats, but not the levels after administration of L-NMMA in SO rats, indicating that there is excessive production of NO in portal hypertensive and PCS rats. Administration of L-arginine counterbalanced the effects of L-NMMA on hyperdynamic circulatory state in portal hypertensive and PCS rats.

CONCLUSION

NO is an important mediator of hyperdynamic circulation in portal hypertension.

The role for endothelin in mesangial proliferative glomerulonephritis

To understand the effect of endothelin (ET) on the mesangium and matrix proliferation on the basis of hyperlipidemia, the model of mesangial proliferative glomerulonephritis (MSPGN) was established by intravenously giving calf serum albumin (250 mg/L) to the rabbits fed on feed containing 1% cholesterol for 4-8 weeks. Our results showed that in the 4th week of the experiment, the ET level in experiment group was significantly higher than that of normal controls (P < 0.01) and the pathological examination revealed development of MSPGN. In the 8th week of the experiment, the ET level was further elevated and pathological study demonstrated local glomerular sclerosis and infiltration of lymphocytes of interstitia. We are led to conclude that ET, as a newly identified hormone, is involved in the pathogenesis and development of MSPGN and acts as an important regulator in the proliferation of mesangium and accumulation of matrix of basal membrane.

Roles of phospholipase C beta2 in chemoattractant-elicited responses

The physiological roles of phospholipase C (PLC) beta2 in hematopoiesis, leukocyte function, and host defense against infection were investigated using a mouse line that lacks PLC beta2. PLC beta2 deficiency did not affect hematopoiesis, but it blocked chemoattractant-induced Ca2+ release, superoxide production, and MAC-1 up-regulation in neutrophils. In view of these effects, it was surprising that the absence of PLC beta2 enhanced chemotaxis of different leukocyte populations and sensitized the in vivo response of the PLC beta2-deficient mice to bacteria, viruses, and immune complexes. These data raise questions about the roles that PLC beta2 may play in signal transduction induced by chemoattractants in leukocytes.

alpha-Latrotoxin stimulates exocytosis by the interaction with a neuronal G-protein-coupled receptor

alpha-Latrotoxin is a potent stimulator of neurosecretion. Its action requires extracellular binding to high affinity presynaptic receptors. Neurexin I alpha was previously described as a high affinity alpha-latrotoxin receptor that binds the toxin only in the presence of calcium ions. Therefore, the interaction of alpha-latrotoxin with neurexin I alpha cannot explain how alpha-latrotoxin stimulates neurotransmitter release in the absence of calcium. We describe molecular cloning and functional expression of the calcium-independent receptor of alpha-latrotoxin (CIRL), which is a second high affinity alpha-latrotoxin receptor that may be the major mediator of alpha-latrotoxin's effects. CIRL appears to be a novel orphan G-protein-coupled receptor, a member of the secretin receptor family. In contrast with other known serpentine receptors, CIRL has two subunits of the 120 and 85 kDa that are the result of endogenous proteolytic cleavage of a precursor polypeptide. CIRL is found in brain where it is enriched in the striatum and cortex. Expression of CIRL in chromaffin cells increases the sensitivity of the cells to the effects of alpha-latrotoxin, demonstrating that this protein is functional in coupling to secretion. Syntaxin, a component of the fusion complex, copurifies with CIRL on an alpha-latrotoxin affinity column and forms stable complexes with this receptor in vitro. Interaction of CIRL with a specific presynaptic neurotoxin and with a component of the docking-fusion machinery suggests its role in regulation of neurosecretion.