Inhibition of platelet aggregation of a mutant proinsulin molecule engineered by introduction of a native Arg-Gly-Asp sequence

A 13 amino acid sequence, CRVARGDWNDNYC, originated from disintegrin eristostatin, was introduced into an inactive human proinsulin molecule between the B29 and A2 sites to replace proinsulin C-peptide by molecular cloning techniques. The constructed Arg-Gly-Asp (RGD)-proinsulin gene was cloned into a temperature-inducible vector pBV220 and expressed in Escherichia coli. The expressed RGD-proinsulin was refolded and purified by Sephadex G50 and DEAE-Sephadex A25 separations. The chemical identity was confirmed by both amino acid composition and mass spectrometry analyses. This RGD-proinsulin showed an inhibitory activity of adenosine 5'-diphosphate-induced human platelet aggregation with an IC50 value of 200 nM. Its insulin receptor binding activity remained as low as 0.03% with native insulin as a control, and its insulin immune activity retained 27.6% compared with proinsulin.

Immunogenicity of a Haemophilus influenzae type b-tetanus toxoid conjugate vaccine when mixed with a diphtheria-tetanus-acellular pertussis-hepatitis B combination vaccine

BACKGROUND

Combination vaccines are urgently needed to reduce the number of injections given to young children. The aim of the study was to evaluate the safety and immunogenicity of a combination vaccine that contains diphtheria and tetanus toxoids and acellular pertussis antigens (DTaP), recombinant hepatitis B surface antigen (HepB) and Haemophilus influenzae type b (Hib) polysaccharide conjugated to tetanus toxoid (PRP-T).

METHODS

Four hundred five infants were randomized equally to three groups and immunized at 2, 4 and 6 months of age with: (1) DTaP/HepB vaccine used to reconstitute lyophilized PRP-T vaccine and administered as a single injection; (2) DTaP/HepB vaccine and PRP-T vaccine administered as two separate injections; or (3) DTaP, HepB and PRP-T vaccines administered as three separate injections. Safety was closely monitored, and blood specimens were obtained to assess antibody responses to each vaccine antigen.

RESULTS

All study vaccines were well-tolerated, and the rates of systemic and injection site reactions were similar between groups. After the third dose the geometric mean antibody concentrations to Hib were significantly lower in subjects in Group 1 (1.63 microg/ml) compared with subjects in Groups 2 and 3 (6.26 and 6.15 microg/ml, respectively; P < 0.0001). Subjects with antibody concentrations <1.0 microg/ml after the third dose responded well to a booster dose of Hib conjugate vaccine given at 11 to 15 months of age (41 of 44 with anti-PRP > or = 1.0 microg/ml). Differences between groups for antibody responses to the other vaccine components were not clinically significant.

CONCLUSIONS

Infants given a combined DTaP/ HepB/PRP-T vaccine experienced a significantly lower antibody response to the PRP-T component than infants given PRP-T vaccine as a separate injection. However, the immune response to a booster dose of Hib conjugate vaccine indicated the presence of immunologic memory.

[The experimental research of the rhBMP-2-induced apoptosis in human glioma cells]

OBJECTIVE

To investigate the effects of recombinant human bone morphogenetic protein (rhBMP-2) on the biological characteristics of human glioma cells (SHG44) in vivo and in vitro.

METHODS

The growth curve of SHG44 cells was ploted with or without rhBMP-2. The proliferation quantity of SHG44 cells with rhBMP-2 was determined by MTT method. The cell cycle, ultrastructure and DNA fragments of SHG44 cells were detected respectively by flow cytometry (FCM), electron microscope and agarose gel electrophoresis. Tumor growth state of SHG44 gliomas, which grew under the skin of nude mice, was observed with local injection of rhBMP-2.

RESULTS

FCM showed that rhBMP-2 inhibited the growth of SHG44 cell in vitro and its effect depended on dosage. DNA content of SHG44 cells in G1 phase was obviously increased (5 mg/L group, 77.4%; control group, 55.2%, P < 0.05) and the content of its S phase was reduced (5 mg/L group, 15.2%; control group, 33.3%, P < 0.01). The apoptosis spike (12.3%) occurred in the 5 mg/L group. The nucleolus chromatin condensation, bound of aggregation and caryorrhexis were observed under the electron microscope and the apoptotic cells appeared. DNA electrophoresis showed a ladder strap (DNA ladder). SHG44 glioma growth was relatively slower and its volume was smaller with the biquadratic local injection of rhBMP-2 (tumor end volume in average: experimental group 894 mm(3) +/- 145 mm(3), control group 5 163 mm(3) +/- 1 028 mm(3), P < 0.01

CONCLUSION

rhBMP-2 can suppress the proliferation of SHG44 gliomas and induce its apoptosisN:

A proprioceptive role for an exteroceptive mechanoafferent neuron in Aplysia

Afferent regulation of centrally generated activity is likely to be more complex than has been established. We show that a neuron that is an exteroceptor can also function as a proprioceptor. We study the Aplysia neuron B21. Previous data suggest that B21 functions as an exteroceptor during the radula closing/retraction phase of ingestive feeding. We show that the tissue innervated by B21, the subradula tissue (SRT), is innervated by a motor neuron (B66) and that B66-induced SRT contractions trigger centripetal spikes in B21. Thus, B21 is also a proprioceptor. To determine whether exteroceptive and proprioceptive activities occur during the same phase of ingestive feeding, we further characterize B66. We show that B66 stimulation does not close or retract the radula. Instead it opens it. Moreover, B66 is electrically coupled to other opening/protraction neurons. Finally, we elicit motor programs in semi-intact preparations and show that during radula opening/protraction we observe B66 activity, SRT contractions, and spikes in B21 that can be eliminated if B66 is indirectly hyperpolarized. B21 is, therefore, likely to act as an exteroceptor during one phase of ingestive feeding and as a proprioceptor during the antagonistic phase. Previous experiments have shown that centripetal spikes in B21 are only transmitted to one follower if they are "gated in" by depolarization. During ingestive programs B21 is centrally depolarized during closing/retraction, but it is not depolarized during opening/protraction. We sought to determine whether there are other followers that receive B21 input when it is not centrally depolarized. We found one such cell. Moreover, we found that stimulation of B21 during radula opening/protraction significantly decreases the duration of this phase of behavior. Thus, proprioceptive activity in B21 is likely to have an impact on motor programs.

Escape swim network interneurons have diverse roles in behavioral switching and putative arousal in Pleurobranchaea

Escape swimming in the predatory sea slug Pleurobranchaea is a dominant behavior that overrides feeding, a behavioral switch caused by swim-induced inhibition of feeding command neurons. We have now found distinct roles for the different swim interneurons in acute suppression of feeding during the swim and in a longer-term stimulation of excitability in the feeding network. The identified pattern-generating swim neurons A1, A3, A10, and their follower interneuron A-ci1, suppress feeding motor output partly by excitation of the I1 feeding interneurons, which monosynaptically inhibit both the feeding command neurons, PC(P), PSE, and other major interneurons, the I2s. This mechanism exerts broad inhibition of the feeding network suitable to an escape response; broader than feeding suppression in learned and satiation-induced food avoidance and acting through a different presynaptic pathway. Four intrinsic neuromodulatory neurons of the swim network, the serotonergic As1-4, add little to direct suppression of feeding. Rather, they monosynaptically excite the serotonergic metacerebral giant (MCG) neurons of the feeding network, themselves intrinsic neuromodulators of feeding, as well as a cluster of adjacent serotonergic feeding neurons, with both fast and slow EPSPs. They also provide mild neuromodulatory excitation of the PC(P)/PSE feeding command neurons, and I1 and I2 feeding interneurons, which is masked by inhibition during the swim. As1-4 also excite the serotonergic pedal ganglion G neurons for creeping locomotion. These observations further delineate the nature of the putative serotonergic arousal system of gastropods and suggest a central coordinating role to As1-4.

A shotgun optical map of the entire Plasmodium falciparum genome

The unicellular parasite Plasmodium falciparum is the cause of human malaria, resulting in 1.7-2.5 million deaths each year. To develop new means to treat or prevent malaria, the Malaria Genome Consortium was formed to sequence and annotate the entire 24.6-Mb genome. The plan, already underway, is to sequence libraries created from chromosomal DNA separated by pulsed-field gel electrophoresis (PFGE). The AT-rich genome of P. falciparum presents problems in terms of reliable library construction and the relative paucity of dense physical markers or extensive genetic resources. To deal with these problems, we reasoned that a high-resolution, ordered restriction map covering the entire genome could serve as a scaffold for the alignment and verification of sequence contigs developed by members of the consortium. Thus optical mapping was advanced to use simply extracted, unfractionated genomic DNA as its principal substrate. Ordered restriction maps (BamHI and NheI) derived from single molecules were assembled into 14 deep contigs corresponding to the molecular karyotype determined by PFGE (ref. 3).

Whole-genome shotgun optical mapping of Deinococcus radiodurans

A whole-genome restriction map of Deinococcus radiodurans, a radiation-resistant bacterium able to survive up to 15,000 grays of ionizing radiation, was constructed without using DNA libraries, the polymerase chain reaction, or electrophoresis. Very large, randomly sheared, genomic DNA fragments were used to construct maps from individual DNA molecules that were assembled into two circular overlapping maps (2.6 and 0.415 megabases), without gaps. A third smaller chromosome (176 kilobases) was identified and characterized. Aberrant nonlinear DNA structures that may define chromosome structure and organization, as well as intermediates in DNA repair, were directly visualized by optical mapping techniques after gamma irradiation.

[Establishment of a heterologous graft model for human breast infiltrating duct carcinoma in nude mice]

A heterologous graft model for human breast infiltrating duct carcinoma is reported in this paper. The grafts derived from an infiltration duct carcinoma of a patient's right breast and her metastatic lymphnode mass were transplanted into the breast pads of nude mice in 1996, and the carcinoma masses were found in breast pads 31 days later. By now, the grafts of carcinoma have been transplanted into nude mice for 15 passages with a full success in 59 mice and with the biological characteristics of the original breast carcinoma. This heterologous graft model was established for the first time in China and the results suggest it be a good model for further research of breast carcinoma.

Fast inactivation of a brain K+ channel composed of Kv1.1 and Kvbeta1.1 subunits modulated by G protein beta gamma subunits

Modulation of A-type voltage-gated K+ channels can produce plastic changes in neuronal signaling. It was shown that the delayed-rectifier Kv1.1 channel can be converted to A-type upon association with Kvbeta1.1 subunits; the conversion is only partial and is modulated by phosphorylation and microfilaments. Here we show that, in Xenopus oocytes, expression of Gbeta1gamma2 subunits concomitantly with the channel (composed of Kv1.1 and Kvbeta1.1 subunits), but not after the channel's expression in the plasma membrane, increases the extent of conversion to A-type. Conversely, scavenging endogenous Gbetagamma by co-expression of the C-terminal fragment of the beta-adrenergic receptor kinase reduces the extent of conversion to A-type. The effect of Gbetagamma co-expression is occluded by treatment with dihydrocytochalasin B, a microfilament-disrupting agent shown previously by us to enhance the extent of conversion to A-type, and by overexpression of Kvbeta1.1. Gbeta1gamma2 subunits interact directly with GST fusion fragments of Kv1.1 and Kvbeta1.1. Co-expression of Gbeta1gamma2 causes co-immunoprecipitation with Kv1.1 of more Kvbeta1.1 subunits. Thus, we suggest that Gbeta1gamma2 directly affects the interaction between Kv1.1 and Kvbeta1.1 during channel assembly which, in turn, disrupts the ability of the channel to interact with microfilaments, resulting in an increased extent of A-type conversion.

Central pattern generator for escape swimming in the notaspid sea slug Pleurobranchaea californica

Escape swimming in the notaspid opisthobranch Pleurobranchaea is an episode of alternating dorsal and ventral body flexions that overrides all other behaviors. We have explored the structure of the central pattern generator (CPG) in the cerebropleural ganglion as part of a study of neural network interactions underlying decision making in normal behavior. The CPG comprises at least eight bilaterally paired interneurons, each of which contributes and is phase-locked to the swim rhythm. Dorsal flexion is mediated by hemiganglion ensembles of four serotonin-immunoreactive neurons, the As1, As2, As3, and As4, and an electrically coupled pair, the A1 and A10 cells. When stimulated, A10 commands fictive swimming in the isolated CNS and actual swimming behavior in whole animals. As1-4 provide prolonged, neuromodulatory excitation enhancing dorsal flexion bursts and swim cycle number. Ventral flexion is mediated by the A3 cell and a ventral swim interneuron, IVS, the soma of which is yet unlocated. Initiation of a swim episode begins with persistent firing in A10, followed by recruitment of As1-4 and A1 into dorsal flexion. Recurrent excitation within the As1-4 ensemble and with A1/A10 may reinforce coactivity. Synchrony among swim interneuron partners and bilateral coordination is promoted by electrical coupling among the A1/A10 and As4 pairs, and among unilateral As2-4, and reciprocal chemical excitation between contralateral As1-4 groups. The switch from dorsal to ventral flexion coincides with delayed recruitment of A3, which is coupled electrically to A1, and with recurrent inhibition from A3/IVS to A1/A10. The alternating phase relation may be reinforced by reciprocal inhibition between As1-4 and IVS. Pleurobranchaea's swim resembles that of the nudibranch Tritonia; we find that the CPGs are similar in many details, suggesting that the behavior and network are primitive characters derived from a common pleurobranchid ancestor.

Optical mapping of Plasmodium falciparum chromosome 2

Detailed restriction maps of microbial genomes are a valuable resource in genome sequencing studies but are toilsome to construct by contig construction of maps derived from cloned DNA. Analysis of genomic DNA enables large stretches of the genome to be mapped and circumvents library construction and associated cloning artifacts. We used pulsed-field gel electrophoresis purified Plasmodium falciparum chromosome 2 DNA as the starting material for optical mapping, a system for making ordered restriction maps from ensembles of individual DNA molecules. DNA molecules were bound to derivatized glass surfaces, cleaved with NheI or BamHI, and imaged by digital fluorescence microscopy. Large pieces of the chromosome containing ordered DNA restriction fragments were mapped. Maps were assembled from 50 molecules producing an average contig depth of 15 molecules and high-resolution restriction maps covering the entire chromosome. Chromosome 2 was found to be 976 kb by optical mapping with NheI, and 946 kb with BamHI, which compares closely to the published size of 947 kb from large-scale sequencing. The maps were used to further verify assemblies from the plasmid library used for sequencing. Maps generated in silico from the sequence data were compared to the optical mapping data, and good correspondence was found. Such high-resolution restriction maps may become an indispensable resource for large-scale genome sequencing projects.

Chromosome 2 sequence of the human malaria parasite Plasmodium falciparum

Chromosome 2 of Plasmodium falciparum was sequenced; this sequence contains 947,103 base pairs and encodes 210 predicted genes. In comparison with the Saccharomyces cerevisiae genome, chromosome 2 has a lower gene density, introns are more frequent, and proteins are markedly enriched in nonglobular domains. A family of surface proteins, rifins, that may play a role in antigenic variation was identified. The complete sequencing of chromosome 2 has shown that sequencing of the A+T-rich P. falciparum genome is technically feasible.

[Relationship of serum trace elements to lung cancer and its clinical application]

The levels of serum trace elements Cu, Zn, Fe, Mn and Ca were measured by PE3030 atomic absorption spectrophotometer in 300 patients with lung cancer, 50 with nonmalignant pulmonary diseases and 100 healthy subjects. In addition, these trace elements were also measured in 60 cases with lung cancer (40 remitted, 20 non-remitted) before and after treatment. Results showed that the concentrations of serum Cu, Mn and Cu/Zn ratio were significantly higher (P < 0.01) but Zn, Ca were significantly lower (P < 0.05-0.01) in lung cancer and nonmalignant pulmonary diseases than in healthy controls. Within the three groups there has no difference among profession, area and age discovered. In the remitted patients with lung cancer, the levels of serum Cu and Cu/Zn ratio were significantly lower (P < 0.01) but Zn, Ca were significantly higher (P < 0.01) after treatment. In the non-remitted group, only Cu/Zn ratio was significantly higher (P < 0.01) after treatment. Multivariable logistic regression analysis showed that the Odds Ratio (OR) of serum Ca was 0.9950 with 95% Confidence interval (CI) 0.9910-0.9990, and the OR of Cu/Zn was 7.9914 with 95% CI 3.4310-18.6134. It was suggested that Ca might play a protective vole while Cu/Zn ratio a risk factor for lung cancer. Results also showed that if the threshold of Cu/Zn ratio set at 1.10 in the healthy control group, the positive rate of Cu/Zn ratio was 68% which might be important in diagnosis and to assessing the prognosis of lung cancer.

Automated high resolution optical mapping using arrayed, fluid-fixed DNA molecules

New mapping approaches construct ordered restriction maps from fluorescence microscope images of individual, endonuclease-digested DNA molecules. In optical mapping, molecules are elongated and fixed onto derivatized glass surfaces, preserving biochemical accessibility and fragment order after enzymatic digestion. Measurements of relative fluorescence intensity and apparent length determine the sizes of restriction fragments, enabling ordered map construction without electrophoretic analysis. The optical mapping system reported here is based on our physical characterization of an effect using fluid flows developed within tiny, evaporating droplets to elongate and fix DNA molecules onto derivatized surfaces. Such evaporation-driven molecular fixation produces well elongated molecules accessible to restriction endonucleases, and notably, DNA polymerase I. We then developed the robotic means to grid DNA spots in well defined arrays that are digested and analyzed in parallel. To effectively harness this effect for high-throughput genome mapping, we developed: (i) machine vision and automatic image acquisition techniques to work with fixed, digested molecules within gridded samples, and (ii) Bayesian inference approaches that are used to analyze machine vision data, automatically producing high-resolution restriction maps from images of individual DNA molecules. The aggregate significance of this work is the development of an integrated system for mapping small insert clones allowing biochemical data obtained from engineered ensembles of individual molecules to be automatically accumulated and analyzed for map construction. These approaches are sufficiently general for varied biochemical analyses of individual molecules using statistically meaningful population sizes.

Serotonin immunoreactivity in the central nervous system of the marine molluscs Pleurobranchaea californica and Tritonia diomedea

The central nervous systems of the marine molluscs Pleurobranchaea californica (Opisthobranchia: Notaspidea) and Tritonia diomedea (Opisthobranchia: Nudibranchia) were examined for serotonin-immunoreactive (5-HT-IR) neurons and processes. Bilaterally paired clusters of 5-HT-IR neuron somata were distributed similarly in ganglia of the two species. In the cerebropleural ganglion complex, these were the metacerebral giant neurons (both species), a dorsal anterior cluster (Pleurobranchaea only), a dorsal medial cluster including identified neurons of the escape swimming network (both species), and a dorsal lateral cluster in the cerebropleural ganglion (Pleurobranchaea only). A ventral anterior cluster (both species) adjoined the metacerebral giant somata at the anterior ganglion edge. Pedal ganglia had the greatest number of 5-HT-IR somata, the majority located near the roots of the pedal commissure in both species. Most 5-HT-IR neurons were on the dorsal surface of the pedal ganglia in Pleurobranchaea and were ventral in Tritonia. Neither the buccal ganglion of both species nor the visceral ganglion of Pleurobranchaea had 5-HT-IR somata. Afew asymmetrical 5-HT-IR somata were found in cerebropleural and pedal ganglia in both species, always on the left side. The clustering of 5-HT-IR neurons, their diverse axon pathways, and the known physiologic properties of their identified members are consistent with a loosely organized arousal system of serotonergic neurons whose components can be generally or differentially active in expression of diverse behaviors.

High-resolution restriction maps of bacterial artificial chromosomes constructed by optical mapping

Large insert clone libraries have been the primary resource used for the physical mapping of the human genome. Research directions in the genome community now are shifting direction from purely mapping to large-scale sequencing, which in turn, require new standards to be met by physical maps and large insert libraries. Bacterial artificial chromosome libraries offer enormous potential as the chosen substrate for both mapping and sequencing studies. Physical mapping, however, has come under some scrutiny as being "redundant" in the age of large-scale automated sequencing. We report the development and applications of nonelectrophoretic, optical approaches for high-resolution mapping of bacterial artificial chromosome that offer the potential to complement and thereby advance large-scale sequencing projects.

Activation of a metabotropic glutamate receptor and protein kinase C reduce the extent of inactivation of the K+ channel Kv1.1/Kvbeta1.1 via dephosphorylation of Kv1.1

Various brain K+ channels, which may normally exist as complexes of alpha (pore-forming) and beta (auxiliary) subunits, were subjected to regulation by metabotropic glutamate receptors. Kv1.1/Kvbeta1.1 is a voltage-dependent K+ channel composed of alpha and beta proteins that are widely expressed in the brain. Expression of this channel in Xenopus oocytes resulted in a current that had fast inactivating and noninactivating components. Previously we showed that basal and protein kinase A-induced phosphorylation of the alpha subunit at Ser-446 decreases the fraction of the noninactivating component. In this study we investigated the effect of protein kinase C (PKC) on the channel. We showed that a PKC-activating phorbol ester (phorbol 12-myristate 13-acetate (PMA)) increased the noninactivating fraction via activation of a PKC subtype that was inhibited by staurosporine and bisindolylmaleimide but not by calphostin C. However, it was not a PKC-induced phosphorylation but rather a dephosphorylation that mediated the effect. PMA reduced the basal phosphorylation of Ser-446 significantly in plasma membrane channels and failed to affect the inactivation of channels having an alpha subunit that was mutated at Ser-446. Also, the activation of coexpressed mGluR1a known to activate phospholipase C mimicked the effect of PMA on the inactivation via induction of dephosphorylation at Ser-446. Thus, this study identified a potential neuronal pathway initiated by activation of metabotropic glutamate receptor 1a coupled to a signaling cascade that possibly utilized PKC to induce dephosphorylation and thereby to decrease the extent of inactivation of a K+ channel.

Serotonin-immunoreactivity in peripheral tissues of the opisthobranch molluscs Pleurobranchaea californica and Tritonia diomedea

The distribution of serotonin (5-HT)-immunoreactive elements in peripheral organs of the sea-slugs Pleurobranchaea californica and Tritonia diomedea was studied in cryostat sections. For Pleurobranchaea, 5-HT-immunoreactive (5-HT-IR) neuron cell bodies were found only in the central nervous system (CNS); 5-HT-IR cell bodies were not observed in foot, tentacles, rhinophores, oral veil, mouth, buccal mass, esophagus, gills, salivary glands, skin, reproductive system, and acidic glands, nor in peripheral tentacle and rhinophore ganglia. However, 5-HT-IR neuronal processes were widely distributed in these structures and the patterns of 5-HT-IR elements were characteristic for each particular peripheral tissue. 5-HT-IR elements were most dense in the sole of the foot and the reproductive system, followed by rhinophores, tentacles, oral veil, mouth, buccal mass, and esophagus. The sensory epithelium of rhinophores, tentacles, and mouth showed a highly structured glomerular organization of 5-HT-IR fibers, suggesting a role for 5-HT in sensory signaling. A much lower density of 5-HT-IR innervation was observed in gills, skin, salivary, and acidic glands. 5-HT-IR was observed in neuropil of tentacle and rhinophore ganglia with many transverse 5-HT-IR axons running to peripheral sensory areas. The distribution of 5-HT-IR elements in Tritonia was similar to that of Pleurobranchaea. A significant suggestion of the data is that central serotonergic neurons may modulate afferent pathways from sensory epithelia at the periphery.

Dedifferentiating initiation and embryogenesis from freshly-isolated microspores of barley

By using DNA-specific fluorescent dye and a confocal laser scanning microscope, the present study was designed to investigate the cytological characteristics of dedifferentiating initiation during pretreatment and embryogenesis during culture in freshly-isolated microspores of barley, and the difference in main developmental pathway between freshly-isolated and cold-treated microspores. The results revealed that (i) freshly-isolated microspores started the initiation within 12 h of mannitol pretreatment, whose main cytological characteristics were that: cell volume was obviously extended; the volume of nuclei and nucleoli were also greatly increased; nucleoli were extremely clear and highly condensed; N/C ratio was very high; (ii) all the pretreatment methods led to the initiation of the microspores, thus triggering the embryogenic process; (iii) pretreatment methods influenced the main developmental pathway of microspores by changing the pattern of the first mitosis. The cold-treated microspores formed main developmental pathway via A patterns, but freshly-isolated microspores via B pattern.

Inactivation of a voltage-dependent K+ channel by beta subunit. Modulation by a phosphorylation-dependent interaction between the distal C terminus of alpha subunit and cytoskeleton

Kv1.1/Kvbeta1.1 (alphabeta) K+ channel expressed in Xenopus oocytes was shown to have a fast inactivating current component. The fraction of this component (extent of inactivation) is increased by microfilament disruption induced by cytochalasins or by phosphorylation of the alpha subunit at Ser-446, which impairs the interaction of the channel with microfilaments. The relevant sites of interaction on the channel molecules have not been identified. Using a phosphorylation-deficient mutant of alpha, S446A, to ensure maximal basal interaction of the channel with the cytoskeleton, we show that one relevant site is the end of the C terminus of alpha. Truncation of the last six amino acids resulted in alphabeta channels with an extent of inactivation up to 2.5-fold larger and its further enhancement by cytochalasins being reduced 2-fold. The wild-type channels exhibited strong inactivation, which could not be markedly increased either by cytochalasins or by the C-terminal mutations, indicating that the interaction of the wild-type channels with microfilaments was minimal to begin with, presumably because of extensive basal phosphorylation. Since the C-terminal end of Kv1.1 was shown to participate in channel clustering via an interaction with members of the PSD-95 family of proteins, we propose that a similar interaction with an endogenous protein takes place, contributing to channel connection to the oocyte cytoskeleton. This is the first report to assign a modulatory role to such an interaction: together with the state of phosphorylation of the channel, it regulates the extent of inactivation conferred by the beta subunit.

Deletion of the N-terminus of a K+ channel brings about short-term modulation by cAMP and beta 1-adrenergic receptor activation

On deletion of the N-terminus of RCK1 K+ channel, acute modulation of the channel by cAMP-elevating treatments is revealed. This modulation is studied in Xenopus oocytes using two-electrode voltage-clamp, site-directed mutagenesis, and SDS-PAGE analyses. Treatments by Sp-8-Br-cAMPS, a membrane-permeant cAMP analog, and by isoproterenol, a beta 1-adrenergic receptor (beta 1R) agonist, both increased the current amplitudes with no effect on the voltage dependency of activation. The effect of isoproterenol was blocked by coexpression of either G alpha S or G alpha i3 proteins. The channel protein is phosphorylated on the Sp-8-Br-cAMPS treatment at Ser446; however, a phosphorylation-deficient variant in which this site has been altered is still modulated by Sp-8-Br-cAMPS and isoproterenol. Expression of the full-length channel with Kv beta 1.1 auxiliary subunit renders the channel at the same modulation as that of the truncated one. Taken together, the RCK1 channel can be acutely modulated by cAMP and beta 1R activation possibly through protein kinase A (PKA) activation, but not through direct channel phosphorylation; the involvement of the N-terminus in this modulation is discussed.

Safety and immunogenicity of a recombinant hepatitis B vaccine administered to infants at 2, 4 and 6 months of age. The Kaiser-UCLA Vaccine Study Group

A recombinant hepatitis B vaccine was administered to over 5000 infants in a prospective, randomized and blinded study. Infants were given either recombinant hepatitis B vaccine (Engerix-B, SmithKline Beecham Pharmaceuticals, 10 micrograms dose-1) or a Haemophilus influenzae type b (Hib) conjugate vaccine at 2, 4 and 6 months of age simultaneously with diphtheria-tetanus-pertussis and oral polio vaccines. Adverse reactions were ascertained by parental reports and interviews, and review of medical records. Blood specimens collected from 269 infants given hepatitis B vaccine were assayed for antibody to hepatitis B surface antigen (anti-HBs) by enzyme immunoassay. Infants given hepatitis B vaccine experienced low rates of adverse reactions that were similar or lower than the rates in infants given Hib conjugate vaccine. The geometric mean anti-HBs concentrations were 9.6 mIU ml-1 after one dose, 333 mIU ml-1 after two doses and 1812 mIU ml-1 after three doses (99% had levels > or = 10 mIU ml-1). Antibody responses to diphtheria and tetanus toxoids were unaffected by simultaneous administration of hepatitis B or Hib conjugate vaccine. Engerix-B vaccine was safe and immunogenic when given with other routine childhood immunizations at 2, 4 and 6 months of age, and should provide long-term protection against hepatitis B virus infection.

Neuronal elements that mediate escape swimming and suppress feeding behavior in the predatory sea slug Pleurobranchaea

1. The white, bilaterally paired A1 interneurons of the cerebropleural ganglion of Pleurobranchaea californica fire rhythmic bursts of action potentials during escape swimming behavior. We studied the role of the A1s in swimming behavior and pattern generation in whole animal and isolated CNS preparations. 2. The escape swim is a cyclic sequence of dorsal and ventral flexions of the body. During the swim, A1 bursts precede and accompany the dorsal flexion phase of the cycle. Hyperpolarization of A1 to prevent spike activity interrupts swimming behavior in the whole animal and fictive swimming in the isolated CNS. Stimulated A1 activity was not observed to cause swimming in whole animals, and was only occasionally sufficient to trigger fictive swimming activity in the isolated CNS. 3. In quiescent whole animal preparations, stimulation of a single A1 normally causes a single dorsal flexion followed by body flexion to the side contralateral to the stimulated cell; characteristically, A1 spike activity stimulates feedback inhibition coinciding with the end of dorsal flexion and the onset of contralateral flexion. 4. A1 spike activity suppresses feeding behavior and causes proboscis retraction in whole animal preparations induced to feed. A1 activity also suppresses fictive feeding driven by stimulation of the critical phasic paracerebral neurons (PCps) of the motor network of feeding in the isolated CNS. Concomitantly, A1 spikes cause potent inhibition of the PCp interneurons. 5. The A1s are specifically excited by noxious mechanical and chemical stimuli, but are not affected by feeding stimuli or the occurrence of feeding behavior. 6. We conclude that the A1 neurons are elements of an escape swimming pattern generator, and that they are probably homologous to the similar C2 neurons of the nudibranch Tritonia diomedea. One of their functions outside of generating the swim pattern may be the suppression of feeding behavior in response to noxious stimulation. These observations provide a neural mechanism for the original observations of the dominance of escape swimming behavior over feeding.

Interstitial space, electrical resistance and ion concentrations during hypotonia of rat hippocampal slices

1. The degree to which mammalian brain cells swell in hypotonic environments has not previously been determined. We exposed hippocampal tissue slices prepared from anaesthetized rats to artificial cerebrospinal fluid from which varying amounts of NaCl had been deleted. Interstitial volume (ISV) change was determined from the volume of dilution of the marker ions tetramethylammonium (TMA+) or tetraethylammonium (TEA+). Tissue electrical resistance was measured as the voltage generated by constant current pulses. 2. ISV decreased as a function of lowered extracellular osmolality (osmotic pressure, pi o), indicating cell swelling. After reaching a minimum, ISV recovered partially, suggesting regulatory volume decrease of cells. After restoring normal pi o the ISV expanded, indicating post-hypotonic cell shrinkage. The electrical resistance of the tissue (Ro) increased when pi o was lowered, due to the reduced ionic strength, as well as restricted ISV. 3. To control for low NaCl concentration, reduced NaCl was replaced by mannitol or fructose. In isosmotic, NaCl-deficient solution, ISV showed inconsistent change, and Ro corrected for ionic strength tended to decrease. 4. Extracellular K+ concentration decreased slightly in low pi o except when spreading depression caused it to increase. Extracellular Ca2+ concentration decreased substantially, consistently and reversibly. Administration of isosmotic low-NaCl concentration solutions caused a similar decrease in extracellular Ca2+ concentrations. We propose that low Na+ concentration in extracellular fluid impaired the extrusion of Ca2+. 5. In severely hypotonic solution, ISV was reduced to 25% of its control volume, corresponding to a mean cell volume increase of at least 11%, probably more. From plotting relative changes in ISV against osmolarity we concluded that, within the range tested, hypotonic cell swelling was not opposed by the close approach of plasma membranes of neighbouring cells.

Factors influencing reflectance spectrophotometric measurements of gastrointestinal mucosal blood flow

Although the technique of endoscopic reflectance spectrophotometry has been applied in clinical studies, factors that modify the reproducibility of measurements have not been assessed systematically. To determine the limitations of the technique, measurements were made while endoscopic light intensity, systemic oxygen saturation, and orientation of the measuring probe were varied. The effects of hemorrhagic hypotension and exposure of the mucosa to 10% dextrose were also studied. When a large number (n = 480) of measurements in the human colon were considered, endoscopic light significantly decreased the index of oxygen saturation (ISO2) and increased the index of hemoglobin concentration (IHB). The decrease in ISO2, however, was small and unlikely to be of clinical importance despite being statistically significant. In one subject with chronic lung disease and baseline hypoxemia, administration of supplemental oxygen significantly increased oxygen saturation at the finger tip as measured by an oximeter and ISO2 of the buccal mucosa as measured by reflectance spectrophotometry. Varying the angle between the measuring probe and the gastric mucosa in rats from 90 degrees to 60 degrees did not affect ISO2 or IHB measurements. At 45 degrees, however, IHB but not ISO2 was significantly increased. Ischemia subsequent to induction of hemorrhagic hypotension and hyperemia induced by administration of 10% dextrose could be demonstrated reproducibly. We conclude that by lowering the intensity of endoscopic light and providing supplemental oxygen, errors in the measurement of IHB and ISO2, respectively, can be minimized. Minor deviations from the perpendicular orientation do not significantly affect ISO2 and IHB measurements. Attention to these details enhances the accuracy of endoscopic reflectance spectrophotometric recordings of ISO2 and IHB in clinical studies.

Interstitial volume changes during spreading depression (SD) and SD-like hypoxic depolarization in hippocampal tissue slices

1. Relative interstitial volume (ISV) was estimated from the concentration changes of iontophoretically administered tetramethyl- and tetraethylammonium (TMA+ and TEA+). Spreading depression (SD) was provoked by high K+, and hypoxic SD-like depolarization (HSD) was induced by withdrawing oxygen. 2. Probe ion concentrations increased dramatically and about equally during SD and HSD, except that in a few hypoxic trials signals became transiently smaller than control. Interstitial volume appeared to decrease on the average by approximately 70%. 3. The ISV that remains patent in CA1 region at the height of SD is < 4% of total tissue volume. Probe ions may occasionally have passed through cell membranes for a short time during hypoxic SD.

Effectiveness and safety of an Haemophilus influenzae type b conjugate vaccine (PRP-T) in young infants. Kaiser-UCLA Vaccine Study Group

OBJECTIVE

To study the safety, immunogenicity, and protective efficacy of the Haemophilus influenzae capsular polysaccharide tetanus conjugate vaccine (PRP-T).

DESIGN

Randomized, double-blind, controlled clinical trial.

SETTING

Southern California Kaiser-Permanente Health Plan.

PARTICIPANTS

10,317 infants 6 to 15 weeks of age, with no known immune dysfunction, exposure to hepatitis B, or contraindication to diphtheria-tetanus-pertussis (DTP) vaccination were enrolled between August 1989 and September 1990.

INTERVENTION

Infants were randomized to receive either PRP-T or a recombinant hepatitis B control vaccine (in addition to DTP) at approximately 2, 4, and 6 months of age.

OUTCOME MEASURES

Adverse reactions occurring during the first 72 hours and between doses (including hospitalizations and outpatient visits) were measured using parental reporting/interviews and review of records. Invasive disease caused by H influenzae was ascertained from the time of enrollment until December 31, 1990.

RESULTS

In October 1990, the study was prematurely terminated because of licensure of other H influenzae vaccines recommended for routine infant use. The rates of systemic and local reactions occurring within 72 hours of each vaccine dose were generally similar for infants given PRP-T and hepatitis B, but some reaction rates (local reactions, fever > or = 102 degrees F, irritability, crying) were significantly higher in the PRP-T group. In the month following receipt of vaccine, PRP-T-vaccinated infants experienced five definite seizures compared with three in the hepatitis B control group. Within 48 hours of vaccination, three seizures (two definite and one possible), which were thought to be related to vaccination, occurred in the PRP-T group, compared with none in the control group (P < .13). Overall morbidity, mortality, and hospitalization rates were similar in the two vaccine groups. Three cases of invasive disease caused by H influenzae occurred in the control group; none occurred in the PRP-T group.

CONCLUSIONS

The PRP-T vaccine is safe and appears to be effective in preventing invasive disease caused by H influenzae type b.

Blockade of antidromic invasion of CA1 pyramidal cells during synaptic activation of NMDA receptors

We have studied in situ the excitability state of the axon-soma membrane of CA1 pyramidal cells in the rat during synaptic activation of N-methyl-D-aspartate (NMDA) receptors. Repetitive activation (3-5 Hz) of Schaffer collaterals provoked a NMDA receptor-mediated component in the field excitatory postsynaptic potential (fEPSP) within 15 s. The generation of this component follows a characteristic self-limiting cycle, vanishing after 6-10 s. When alvear shocks were paired to the orthodromic volleys, the antidromic population spike (PS) was completely abolished only if the NMDA receptor-mediated fEPSP had occurred. This blockade of antidromic invasion lasted for 120-150 ms after each orthodromic shock. A reduction in the safety factor for axon-soma transmission is presumed during NMDA receptor synaptic activation.

Role of calcium channels in spreading depression in rat hippocampal slices

In the CA1 region of rat hippocampal slices, spreading depression (SD) was provoked by a brief period of hypoxia or by localized application of high potassium solution. We measured extracellular DC voltage (Vo), extracellular potassium concentration ([K+]o) and/or extracellular Ca2+ concentration ([Ca2+]o). SD was provoked under control conditions and also when voltage-gated Ca2+ channels were blocked by application of 2 mM Ni2+ or Co2+. In some experiments, CPP, DNQX, or the two together were also applied to block glutamate receptor-coupled channels. When SD was provoked by hypoxia, these treatments significantly increased the latency of SD onset and decreased the amplitudes of the accompanying delta Vo, delta [Ca2+]o and delta [K+]o. Hypoxia-induced SD was never blocked completely, however and delta [Ca2+]o was reduced at most by 50%. When SD was provoked by application of high K+ solution near the recording site, Ni2+ or Co2+ partially suppressed the Vo and [Ca2+]o shifts but did not block SD altogether. When high K+ solution was applied at a distance, Ni2+ or Co2+ blocked the propagation of SD to the recording site. We conclude that during SD, a significant proportion of the calcium ions flowing into neurons does not pass through voltage-gated or glutamate receptor-linked channels.

Mechanism of spreading depression: a review of recent findings and a hypothesis

Spreading depression of Leão (SD) can be provoked by numerous nonspecific mechanical, electrical, and chemical stimuli. A similar, if not identical, phenomenon can be provoked by hypoxia. SD is characterized by drastic depolarization of neurons, severe reduction of membrane resistance, and redistribution of ions across cell membranes. Glial cells also depolarize but retain membrane resistance. Tetraethylammonium hastens the onset of hypoxic SD but reduces the sustained potential shift and K+ outflow from cells; 4-aminopyridine also accelerates SD but has no effect on the voltage shift. N-Methyl-D-aspartate receptor antagonists delay the onset of SD, while nickel and cobalt reduce the amplitude of SD-related redistribution of Ca2+. Yet, no specific blocker of SD has been found. Microdialysis of high-K+ solution in hippocampal CA1 region induces recurrent waves of SD propagating semi-independently in adjacent tissue layers, and a prolonged unstable depressed state that has not previously been described. Neither the release of K+ ions nor of glutamate is the unique agent of SD propagation. On the basis of recent findings we propose a hypothetical sequence of events that reconcile many of the previously seemingly paradoxical observations.

Lasting neuron depression induced by high potassium and its prevention by low calcium and NMDA receptor blockade

Spreading depression-like neuron depolarization was induced in CA1 of hippocampal tissue slices by irrigation with artificial cerebrospinal fluid containing 133.5 mM K+ for 8-40 min. Evoked responses disappeared during irrigation with high-K+ solution. Following 8-20 min irrigation orthodromic responses showed a triphasic recovery cycle: early partial return with evidence of neuron hyperexcitability, then secondary depression and finally slow partial recovery. After 30 min or more of high-K+ exposure, ortho- and antidromic responses remained severely depressed for at least 5.5 to 6.5 h. When, however, the tissue was deprived of calcium, or N-methyl-D-aspartate (NMDA) receptors were blocked by 10 microM 3-((+-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), then evoked responses recovered partially after a 30- or 40-min high-K+ exposure. Post-exposure hyperexcitability was not prevented by CPP. We conclude that prolonged depolarization by elevated K+ causes irreversible neuron damage, which is triggered or accelerated by influx of calcium ions into neurons, mediated in part by NMDA receptor activation.

Ion channel involvement in hypoxia-induced spreading depression in hippocampal slices

Rat hippocampal tissue slices were made hypoxic in control medium and in medium containing the ion channel blockers tetraethylammonium (TEA), 4-aminopyridine (4-AP), or tetrodotoxin (TTX). Postsynaptic evoked potentials, extracellular DC potential Vec, and in some experiments extracellular potassium concentration [K+]o were monitored in stratum pyramidale of the CA1 region. TEA (10 mM) decreased the latency of hypoxia-induced spreading depression (SD), and reduced the amplitudes of the changes in Vec and [K+]o. 4-AP (50 microM) also decreased the latency of SD but had no effect on the Vec shift. In most slices, TTX (1 microM) increased SD latency but had no effect on the Vec shift. In some slices, TTX blocked the occurrence of SD.

[A microcomputer processing system of evoked potentials of brain slices and applied examples]

Processing the evoked potentials of neurons with a computer can greatly increase the efficiency of data processing and obtain much more information from the data. Besides, it renders possibility of large quantities and prolonged observation. In this system, DMA mode is used for data transfer from A/D card to the computer, so total processing program including sampling subroutine was made in BASIC language. This article introduces the functions of this program in processing data and the technique in making this program.

Development of calcium channels in gastric smooth muscle

We used [3H]nitrendipine to characterize dihydropyridine sensitive calcium channels on cells isolated from neonatal (1 d) and weanling (11 wk) rabbit gastric fundic and antral smooth muscle. Incubating with and without nifedipine 20 microM, specific binding was 56 +/- 4% of total binding at 0.1 nM [3H]nitrendipine. Specific binding was saturable, reversible, achieved equilibrium by 10 min at 4 degrees C, and was linearly related to cell concentration. The affinity constant for [3H]nitrendipine was higher in weanling fundus (kd = 243 +/- 121 pM) versus antrum (kd = 771 +/- 190 pM), p less than 0.05. There were no age-related changes in affinity. In the antrum, the number of binding sites (Bmax) increased from 6,000 +/- 266/cell in neonates to 27,500 +/- 8,440/cell in weanlings (p less than 0.05). In the fundus Bmax was 7,750 +/- 2,100/cell in neonates, and there was no age-related change. To assess function, we compared isometric stress in full thickness muscle strips oriented to the circular layer. Bethanechol stimulated dose-dependent tonic contractions in the fundus and phasic contractions in the antrum. Maximal stress increased with age from 305 +/- 54 mN/cm2 to 1140 +/- 73 mN/cm2 (p less than 0.05) in the fundus and from 72 +/- 20 mN/cm2 to 154 +/- 30 mN/cm2 (p less than 0.05) in the antrum. Preincubation and incubation without calcium resulted in reversible inhibition of contraction at both ages. Nifedipine 10-microM inhibited 100% of bethanechol-stimulated contraction in the antrum, but only 25% in the fundus at both ages.(ABSTRACT TRUNCATED AT 250 WORDS)

Association between postprandial changes in colonic intraluminal pressure and transit

The aim of this study was to correlate the movement of colonic luminal contents with the changes in intraluminal pressure. Studies were performed in 9 healthy volunteers. Intraluminal pressure was measured with perfused catheter ports in the transverse, splenic flexure, descending, and sigmoid colon. Movement of the luminal contents was measured by following the movement of technetium 99m-ethylenetriamine-pentaacetic acid that was instilled as a bolus in the splenic flexure. During fasting there was very little change in pressure or in the movement of intraluminal contents. After eating a 1000-kcal meal, the tracer moved from the splenic flexure into the transverse colon and the sigmoid colon. Nonpropagating colonic motor activity increased in all colonic segments immediately after eating the meal (p less than 0.05). The increase in motility was significantly greater in the descending colon than in the transverse and sigmoid colon (p less than 0.05). In one-half of the subjects propagating contractions occurred postprandially. The movement of the intraluminal tracer occurred during both types of motility. The nonpropagating contractions were associated with a gradual movement of the luminal contents. The direction of the movement of the contents was determined by the differences in pressure in the different segments of the colon. The propagating contractions were associated with a rapid movement of intraluminal contents. These studies suggest that (a) colonic motility and transit are quiescent during fasting and (b) the transverse colon acts as a mixing and storage area, as retrograde transit into the transverse colon is the characteristic postprandial pattern.

Development of the muscarinic receptor in rabbit gastric smooth muscle

We used binding of [N-methyl-3H]scopolamine ( [3H]-NMS) to tissue homogenates and isometric contraction of muscle strips to characterize perinatal changes in the muscarinic receptor on rabbit gastric smooth muscle. In homogenates from fetal (28 days of gestation), 1-, 3-, and 7-day, 4- and 11-wk-old rabbits, specific binding was saturable and temperature dependent, achieved equilibrium by 10 min at 30 degrees C, and was linearly related to tissue concentration. Specific binding was 80 +/- 2% of total binding at 0.2 nM [3H]NMS. The number of binding sites was 120,000 receptors/cell, maximal during the first week of life compared with the fetus or older animals. Affinity of [3H]NMS was highest in the first week of life (Kd = 345 +/- 24 pM, 1 day old). Age did not affect Hill coefficients or Ki values; secoverine and 4-diphenylacetoxy-N-methylpiperidine methiodide were 50-fold more potent than pirenzepine. In muscle strips, bethanechol stimulated dose-dependent atropine-inhibitable isometric contraction. The doses required for half-maximal contraction were similar in both age groups (5-6 microM), but maximal contraction was fivefold greater in weanlings compared with neonates. Increasing extracellular potassium concentration resulted in similar differences, suggesting that the differences were not receptor related. These results suggest that well-differentiated M2-muscarinic receptors are functional on rabbit gastric smooth muscle during the perinatal period.

Risk factors for cancer of the testis in young men

An individual matched case-control study of testis cancer in 131 men under age 40 was conducted to investigate antecedent risk factors including events during prenatal life. Ten patients were born with an undescended testis compared to only two controls (p less equal to 0.02), a previously reported risk factor. Two new risk factors were uncovered: six patients-mothers received hormones during the index pregnancy compared to only one control-mother, and eight patient-mothers and two control-mothers reported excessive nausea as a complication of the index pregnancy. A hypothesis linking these three factors is presented: viz, that a major risk factor for testis cancer is a relative excess of certain hormones (in particular estrogen) at the time of differentiation of the testes.

Histocompatibility leukocyte antigen patterns in nasopharyngeal carcinoma cases from California

Histocompatibility leukocyte antigen (HLA)-A2 in the first locus and less than two antigens in the second locus were found to be significantly associated with an increased risk to nasopharyngeal carcinoma in Chinese. HLA-A2 in the first locus alone was responsible for the increased risk. No significant HLA patterns were found to be associated with the Caucasian population.