A protein interaction map of Drosophila melanogaster

Drosophila melanogaster is a proven model system for many aspects of human biology. Here we present a two-hybrid-based protein-interaction map of the fly proteome. A total of 10,623 predicted transcripts were isolated and screened against standard and normalized complementary DNA libraries to produce a draft map of 7048 proteins and 20,405 interactions. A computational method of rating two-hybrid interaction confidence was developed to refine this draft map to a higher confidence map of 4679 proteins and 4780 interactions. Statistical modeling of the network showed two levels of organization: a short-range organization, presumably corresponding to multiprotein complexes, and a more global organization, presumably corresponding to intercomplex connections. The network recapitulated known pathways, extended pathways, and uncovered previously unknown pathway components. This map serves as a starting point for a systems biology modeling of multicellular organisms, including humans.

Purification and localization of a 10 kDa calcareous corpuscle binding protein of Spirometra mansoni plerocercoid

In cestode parasites, calcareous corpuscles are thought to be associated with a number of intracellular physiologies by regulating the trafficking of mineral components. We previously separated these particular components by Ficoll, and their binding proteins of 10 kDa and 35 kDa in the Spirometra mansoni plerocercoid (sparganum). In the present study, we purified a 10 kDa protein employing octyl-Sepharose CL-4B affinity chromatography. Anti-serum raised against the purified protein showed specific reactions to the calcareous corpuscles of the worm section by immunohistochemistry, and recognized the 10 kDa protein by immunoblotting.

Matrix-assisted laser desorption/ionization detection of polymerase chain reaction products by utilizing the 5'-3' exonuclease activity of Thermus aquaticus DNA polymerase

The 5'-3' exonuclease activity of DNA polymerase was utilized in the polymerase chain reaction system to generate a specific signal concomitant with amplification. These signals were detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). This method obviates the need to perform extensive DNA purification of reaction products that is often necessary for detecting larger DNA molecules by mass spectrometry. Oligonucleotides complementary to the internal region of the amplicon are degraded by the 5'-3' exonuclease activity and the degradation products are analyzed by MALDI mass spectrometry. We refer to this assay as the Exo-taq assay or probe degradation assay. This method should be amenable to automation.

[Effects of Lewis Y oligosaccharide on secretion and gene expression of EGF and EGF-R in mouse embryos]

Implantation is a complicated developmental process. Some hormones and cytokines are involved in the regulation of the implantation by regulating functions of the endometrium and the embryo. Oligosaccharide antigen Lewis Y is specifically expressed on embryo surface and plays an important role in implantation. In this study, effects of Lewis Y on secretion and gene expression of EGF and EGF receptor of the embryo were investigated. Embryos were pre-incubated with Le(Y) specific antibody AH6 for 3 h, then antibody was removed, immuno-dot blots and RT-PCR were used to analyze the secretion of EGF and EGF receptor and their gene expression in the embryo at different times after pre-incubation. The results showed that, when blocked by AH6 antibody for 1.5 h, the secretion and expression of EGF in the embryo were significantly declined, and the alteration was continued to over 6 h; and those of EGF-R were slightly decreased after blocking. The results suggest that Lewis Y oligosaccharide on the surface of embryo may be involved in the regulation of embryo development and implantation, by affecting the expression and secretion of EGF in embryo.

Dynamic mechanisms of the membrane water channel aquaporin-1 (AQP1)

Molecular-dynamics simulations were performed on the structures of the water channel aquaporin-1. The results provide an atomistic description of the interactions involved in the water permeation. Two major curvilinear pathways were identified. The simulations confirmed that the water selectivity is due primarily to the size-exclusion effect; i.e., maximally, one water molecule is allowed to pass through the narrow constriction in the aqueous pathway. Most importantly, in contrast to previous proposals, the hydrogen-bonding interactions of water molecules with the polar side chains of Asn-76 and Asn-192 on the strictly conserved Asn-Pro-Ala sequence motifs were found to be essential for maintaining the connectivity of water flow in the narrow constriction region. When Asn-76 and Asn-192 were replaced with near-isosteric hydrophobic residues in the simulation, the aqueous pathways were broken completely. Additionally, the size of the narrow constriction fluctuates significantly during the simulation, which frequently breaks the flow of water and, thus, breaks the single-file water network necessary for proton translocation. Moreover, mutations based on the simulation also have been suggested for further experimental investigation of the water-permeation mechanism of aquaporin-1.

Enhanced delayed-type hypersensitivity and diminished immediate-type hypersensitivity in mice lacking the inducible VPAC(2) receptor for vasoactive intestinal peptide

Vasoactive intestinal peptide (VIP) and its G protein-coupled receptors, VPAC(1)R and VPAC(2)R, are prominent in the immune system and regulate many aspects of T cell-dependent immunity. In mouse T cells, VPAC(1)R is expressed constitutively, whereas VPAC(2)R is induced by immune stimuli. VPAC(2)R-null (VPAC(2)R(-/-)) mice on a C57BL/6 background are shown here to have normal basic immune characteristics, including serum Ig concentrations, blood levels of all leukocytes, and spleen number of total T cells (CD3(+)) and T cells bearing CD4, CD8, and CD28. Hapten-evoked cutaneous delayed-type hypersensitivity (DTH) was significantly enhanced in VPAC(2)R-null mice compared with age- and sex-matched wild-type mice. In contrast, generation of IgE anti-hapten antibodies and active cutaneous anaphylaxis were > or =70% lower in VPAC(2)R-null mice than in wild-type controls. Cytokine production by splenic CD4(+) T cells, stimulated with adherent anti-CD3 plus anti-CD28 antibodies, revealed higher levels of IL-2 (mean = 3-fold) and IFN-gamma (mean = 3-fold), and lower levels of IL-4 (mean = one-fifth) in VPAC(2)R-null mice than wild-type controls. Loss of VIP-VPAC(2)R maintenance of the normal ratio of Th2/Th1 cytokines thus leads to a state of enhanced DTH and depressed immediate-type hypersensitivity, which may alter both host defense and susceptibility to immune-mediated diseases.

Allergic diathesis in transgenic mice with constitutive T cell expression of inducible vasoactive intestinal peptide receptor

Vasoactive intestinal peptide (VIP) and its G-protein-coupled receptors (VPAC1 and VPAC2 Rs) are prominent in the immune system. In T cells, VPAC1 R is expressed constitutively whereas VPAC2 R is induced only after stimulation of the T cell receptor (TCR) or exposure to some cytokines. VPAC1 R and VPAC2 R also transduce different effects of VIP on T cells. Constitutive expression of VPAC2 R selectively in CD4+ T cells (helper-inducer Th cells) of transgenic (TG) C57BL/6 mice directed by the lck tyrosine kinase promoter is now shown to evoke production of more Th2-type interleukins 4 and 5, and less Th1-type interferon gamma after TCR activation. VPAC2 R TG mice consequently have significant elevations of blood IgE, IgG1, and eosinophils. VPAC2 R TG mice also show increased IgE antibody responses, which mediate heightened cutaneous allergic reactions, and have depressed delayed-type hypersensitivity. VIP enhancement of the ratio of Th2 cell to Th1 cell cytokines thus evokes an allergic state in normally nonallergic mice, which suggests the possibility of neuropeptide contributions to immune phenotypic alterations in human hypersensitivity diseases.

Expression, purification, immunological characterization and application of Escherichia coli-derived hepatitis C virus E2 proteins

The envelope glycoprotein E2 of hepatitis C virus (HCV) has been shown to bind human target cells. Anti-E2 antibodies have been associated with both recovery from natural infection in humans and protection from challenge with homologous HCV in chimpanzees. Therefore E2 has become a major target for the development of anti-HCV vaccines. Two E2 fragments [amino acids (aa) 450-565 and aa 385-565] derived from a subtype 1b HCV genome were expressed as N-terminally hexahistidine-tagged proteins in Escherichia coli and purified to over 85% purity. Both proteins were specifically recognized by homologous hepatitis-C-patient's serum on Western blotting, suggesting that these E. coli-derived E2 proteins displayed E2-specific antigenicity. E2-116 (aa 450-565) elicited strong antibody responses in BALB/c mice and rabbits. Rabbit antiserum raised against renatured E2-116 (R(E2-116R)) was able to recognize subtype 1b and 1a E2 glycoproteins expressed in mammalian cells on Western blotting. E2-181 (aa 385-565) reacted with 40% of anti-HCV(+) patients' sera in ELISA. R(E2-116R) and E2-181 were successfully used in preliminary modified vaccinia virus Ankara- and DNA-based E2 vaccine studies for detecting antigen expression in vitro and assessing induced humoral immune responses in mice. The E2 proteins and rabbit antiserum reported here could find wider applications in the development of effective diagnostic, prophylactic and therapeutic measures against HCV.

Curtailing unnecessary vancomycin usage in a hospital with high rates of methicillin resistant Staphylococcus aureus infections

AIMS

To implement and monitor the effectiveness of a strategy to curb unnecessary use of vancomycin and teicoplanin for inpatients in a teaching hospital/tertiary referral centre where 33% of S. aureus isolates (72% from ICU patients) were methicillin resistant.

METHODS

A sample of 182 vancomycin/teicoplanin inpatient prescriptions surveyed, revealed that only 31 (17%) conformed with Centre for Disease Control (CDC) guidelines. Following education (ward-rounds, bulletins) on appropriate CDC based guidelines for prescribing glycopeptides directed at relevant clinicians, 'Immediate Concurrent Feedback' (ICF) was gradually deployed throughout the hospital. This entailed review of respective inpatient records on the next working day. If the indication was deemed not to conform with our guidelines, the prescriber was issued a memo (copied to the supervising doctor). Each memo detailed the 'errant' incident, listed appropriate indications and explicitly advised desisting from such prescribing and suggested alternative therapy if necessary. Corresponding glycopeptide usage data for our hospital and others in Hong Kong were retrieved and analysed as were samples of records of our inpatients with staphylococcal septicaemia (pre and during ICF).

RESULTS

Compared with baseline values, during 2 years of ICF, inpatient prescribing of vancomycin and teicoplanin deemed to conform increased to 71% (773/1086); difference 54% (P < 0.0001, 95% CIs 47-62%). Corresponding average monthly usage (DDDs/1000 admissions) decreased from 76 (pre-ICF) to 45; mean difference 31 (P < 0.0001, 95% CIs 24, 38). Mortality from staphylococcal bacteraemia remained unchanged. No comparable changes in glycopeptide usage ensued in comparator hospitals.

CONCLUSIONS

ICF can be used safely to curb irrational overuse of vancomycin and teicoplanin in a hospital with high methicillin resistant S. aureus infection rates.

CsRn1, a novel active retrotransposon in a parasitic trematode, Clonorchis sinensis, discloses a new phylogenetic clade of Ty3/gypsy-like LTR retrotransposons

We screened the genome of a trematode, Clonorchis sinensis, in order to identify novel retrotransposons and thereby provide additional information on retrotransposons for comprehensive phylogenetic study. Considering the vast potential of retrotransposons to generate genetically variable regions among individual genomes, randomly amplified polymorphic DNAs (RAPDs) detected by arbitrarily primed polymerase chain reactions were selected as candidates for retrotransposon-related sequences. From RAPD analysis, we isolated and characterized a novel retrotransposon in C. sinensis as the first member of uncorrupted long-terminal-repeat (LTR) retrotransposons in phylum Platyhelminthes. The retrotransposon, which was named Clonorchis sinensis Retrotransposon 1 (CsRn1), showed a genomewide distribution and had a copy number of more than 100 per haploid genome. CsRn1 encoded an uninterrupted open reading frame (ORF) of 1,304 amino acids, and the deduced ORF exhibited similarities to the pol proteins of Ty3/gypsy-like LTR retrotransposons. The mobile activity of master copies was predicted by sequence analysis and confirmed by the presence of mRNA transcripts. Phylogenetic analysis of Ty3/gypsy-like LTR retrotransposons detected a new clade comprising CsRn1, Kabuki of Bombyx mori, and an uncharacterized element of Drosophila melanogaster. With its high repetitiveness and preserved mobile activity, it is proposed that CsRn1 may play a significant role in the genomic evolution of C. sinensis.

Epidemiological significance of sero-positive inhabitants against sparganum in Kangwon-do, Korea

Sparganum is a plerocercoid of pseudophyllidean tapeworms, Diphyllobothrium or Spirometra spp. Human sparganosis is endemic mainly in East and Southeast Asian countries where the custom of eating raw snake or frog meat, or poulticing with snake's skin exists. From January 1995 to November 1999, an epidemiological survey was undertaken to evaluate the serum levels of anti-sparganum specific IgG antibodies in Whachon-gun residents, Korea. An enzyme- linked immunosorbent assay (ELISA) and immunoblot analysis of the sera from 316 subjects were used. In addition, a stool examination from 416 inhabitants and questionnaires regarding the consumption of raw meat were given. Out of 416 inhabitants examined coprologically, one was infected with Clonorchis sinensis and two were infected with Metagonimus spp. The sera from 36 inhabitants (11.4 %) showed a positive reaction to the sparganum antigen. Out of these 36 inhabitants, the sera from 25 people were examined 7, 19, and 50 months later. The sera were found to still show positive reactions without any remarkable changes of anti-sparganum specific antibody titers except for one. An analysis of the questionnaires suggested that a history of eating of raw snakes or frogs was important risk factor for clinical or covert sparganosis (odd ratio=15.6 and 3.1, respectively).

Cardiac-specific LIM protein FHL2 modifies the hypertrophic response to beta-adrenergic stimulation

BACKGROUND

A deficiency of muscle LIM protein results in dilated cardiomyopathy, but the function of other LIM proteins in the heart has not been assessed previously. We have characterized the expression and function of FHL2, a heart-specific member of the LIM domain gene family.

METHODS AND RESULTS

Expression of FHL2 mRNA and protein was examined by Northern blot, in situ hybridization, and Western blot analyses of fetal and adult mice. FHL2 transcripts are present at embryonic day (E) 7.5 within the cardiac crescent in a pattern that resembles that of Nkx2.5 mRNA. During later stages of cardiac development and in adult animals, FHL2 expression is localized to the myocardium and absent from endocardium, cardiac cushion, outflow tract, or coronary vasculature. The gene encoding FHL2 was disrupted by homologous recombination, and knockout mice devoid of FHL2 were found to undergo normal cardiovascular development. In the absence of FHL2, however, cardiac hypertrophy resulting from chronic infusion of isoproterenol is exaggerated (59% versus 20% increase in heart weight/body weight in FHL null versus wild-type mice; P<0.01).

CONCLUSIONS

FHL2 is an early marker of cardiogenic cells and a cardiac-specific LIM protein in the adult. FHL2 is not required for normal cardiac development but modifies the hypertrophic response to beta-adrenergic stimulation.

[Polycystic ovaraian syndrome and hyperinsulinemia]

OBJECTIVE

To identify the relationship between polycystic ovarian syndrome and hyperinsulinemia.

METHODS

Age, body height, body weight, serum estradiol, progesterone, testosterone, follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), triiodothyronine (T3), tetraiodothyronine (T4), insulin, oral glucose tolerance test (OGTT), and cortisol were measured in 28 patients with polycystic ovarian syndrome (PCOS).

RESULTS

Sxiteen patients (57.1% of total) had hyperinsulinemia. Among them one patient was found diabetic. No difference was noted in age, height, body weight, body mass index, serum estradiol, progesterone, testosterone, FSH, LH, PRL, T3, T4, cortisol, and glucose of OGTT between hyperinsulinemia and non-hyperinsulinemia patients. However the LH/FSH ratio (2.4 +/- 1.5) in hyperinsulinemia patients was significantly higher than 1.2 +/- 0.6 in non-hyperinsulinemia patients (P = 0.0125). In addition, the results showed that the fasting serum insulin, insulin after OGTT, the insulin/glucose ratio at 30, 120 minutes, 180 minutes, the area under curve of and the insulin, insulin resistant index (IRI) were higher in hyperinsulinemia pateints than in non-hyperinsulinemia patients respectively. Furthermore, the fasting insulin level, insulin/glucose ratio were found to be negatively related to insulin sensitivity index and positively related with beta-cell functioning index.

CONCLUSION

Hyperinsulinemia and insulin resistance accompany with some of the PCOS patients in China. Further investigations will be necessary to clarify the relevant mechanisms.

Adaptive mechanisms that preserve cardiac function in mice without myoglobin

Mice lacking myoglobin survive to adulthood and meet the circulatory demands of exercise and pregnancy without cardiac decompensation. In the present study, we show that many myoglobin-deficient embryos die in utero at midgestation with signs of cardiac failure. Fetal mice that survive to gestational day 12.5, however, suffer no subsequent excess mortality. Survival in the absence of myoglobin is associated with increased vascularity and the induction of genes encoding the hypoxia-inducible transcription factors 1alpha and 2, stress proteins such as heat shock protein 27, and vascular endothelial growth factor. These adaptations are evident in late fetal life, persist into adulthood, and are sufficient to maintain normal myocardial oxygen consumption during stressed conditions. These data reveal that myoglobin is necessary to support cardiac function during development, but adaptive responses evoked in some animals can fully compensate for the defect in cellular oxygen transport resulting from the loss of myoglobin.

Cost-effectiveness of screening x-rays at admission to acute rehabilitation after joint replacement surgery: a retrospective chart review

OBJECTIVE

To investigate the cost-effectiveness of performing routine screening x-rays for patients on admission to an acute rehabilitation facility, after hip or knee replacement surgery, by reviewing the overall incidence of abnormal radiographic findings and determining their impact on patient care and outcome.

DESIGN

A retrospective chart review study, in which 592 patients were admitted, after hip or knee replacement surgery, to three acute inpatient rehabilitation facilities under one system.

RESULTS

Eight of 592 admissions revealed abnormal screening x-rays, for an overall incidence of 1.35%. All of the eight abnormal radiologic cases remained medically stable throughout their acute rehabilitation stay. The abnormalities did not alter the patients' medical management or length of stay. One case, which had demonstrated normal admission films, revealed a dislocated hip prosthesis on a follow-up x-ray, which was obtained as a result of new onset hip pain. The patient was subsequently transferred back to the acute care hospital for surgical correction.

CONCLUSIONS

The authors found a relatively low incidence of abnormal admission x-ray findings; furthermore, the detection of abnormal admission films did not alter patient care or outcome. The results suggested that performing routine admission radiologic studies on all patients after joint replacement surgery or hemiarthroplasty may not be a cost-effective screening tool in rehabilitation.

Clonorchis sinensis: molecular cloning and characterization of 28-kDa glutathione S-transferase

A 28-kDa glutathione S-transferase (Cs28GST) was purified from a Clonorchis sinensis cytosolic fraction through anion-exchange and glutathione-affinity column chromatographies. A monoclonal antibody raised against Cs28GST reacted specifically to the C. sinensis antigen among trematode proteins. A putative peptide of 212 amino residues deduced from a cDNA clone appeared homologous with 28-kDa GST of trematodes, and its secondary structural elements predicted a GSH-binding site. Recombinant Cs28GST showed GST enzyme activity with CDNB substrate and was sensitive to the model inhibitors. The recombinant Cs28GST was antigenically indistinguishable from the native form and was recognized specifically by C. sinensis-infected human sera. The Cs28GST was localized in the tegument and underlying mesenchymal tissues. It is suggested that Cs28GST may play significant physiological roles against bioreactive molecules and be a useful reagent for serodiagnosis of clonorchiasis.

[Differences of anatomic variations in ostiomeatal complex between two sides of the deviated septum]

OBJECTIVE

To explore the influence of the deviated septum on the development of ostiomeatal complex (OMC).

METHODS

Nasal endoscopic examination and CT scan of the paranasal sinuses of 103 patients with nasal septal deviation were analyzed. The differences of anatomic variations in OMC between ipsilateral and contralateral sides in relation to the direction of septal deviation. The incidence of sinusitis on either side of the deviated septum was evaluated.

RESULTS

On the side opposite to the deviated septum, the incidence of middle and inferior turbinate hypertrophy was higher than that of the deviated side(P < 0.05). The width of agger nasi and ethmoid bulla was on the contralateral side larger than that of the ipsilateral side (P < 0.01). The incidence of paradoxical curvature of middle turbinate on the ipsilateral side was higher than that of contralateral side (P < 0.01). Other anatomic variations showed no significant differences between two sides of the deviated septum (P > 0.05), nor was there any difference between the incidence of sinusitis on the two sides.

CONCLUSION

Some compensatory changes in middle and inferior turbinates and lateral nasal-wall on the opposite side to the deviation might be caused by the deviated septum.

Vasoactive intestinal peptide mediation of development and functions of T lymphocytes

The first phase in investigating neural regulation of immunity has delineated anatomical connections, shared mediators and receptors for mediators with distinctive effects, and the immune functional consequences of altering relevant neural activities. Vasoactive intestinal peptide (VIP) and pituitary adenylyl cyclase-activating peptide (PACAP) are represented prominently in immune organs. They have potent novel effects on many aspects of immunity, are derived from and serve as autacoids in some sets of immune cells, and they participate in both physiological and pathological immune responses. The present phase of neuroimmune research has begun to elucidate the genetic determinants of expression and functions of neuromediators in immunity. Our evolving understanding of the novel mechanisms for adaptation and specificity in the VIP/PACAP neuroimmune network suggests the importance of immunoselective transcriptional control of expression of VIP/PACAP receptors in T cells, a dominant role for numerous cytokines, and the critical involvement of small subsets of VIP-/PACAP-responsive thymocytes and T cells.

Lysophosphatidic acid receptor-selective effects on Jurkat T cell migration through a Matrigel model basement membrane

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) from platelets and mononuclear phagocytes mediate T cell functions through endothelial differentiation gene-encoded G protein-coupled receptors (Edg Rs) specific for LPA (Edg-2, -4, and -7) or S1P (Edg-1, -3, -5, -6, and -8). Jurkat leukemic T cells with the SV40 virus large T Ag (Jurkat-T cells) express Edg-3>-2>-4 Rs, as assessed by RT-semiquantitative PCR and Western blots with anti-Edg R mAbs. Jurkat-T cells expressing predominantly Edg-2 R (Jurkat-T-2 cells) and Edg-4 R (Jurkat-T-4 cells) were developed by cotransfection with the respective sense plasmids and a mixture of antisense plasmids for the other Edg Rs, and hygromycin selection. Migration of Jurkat-T-4 cells, but not Jurkat-T-2 cells, through a layer of Matrigel on a 5-um pore polycarbonate filter was stimulated up to 5-fold by 10(-9) to 10(-6) M LPA and by 30-300 ng/ml of anti-Edg-4 R Ab, but not anti-Edg-2 R Ab. LPA and anti-Edg-4 R Ab also enhanced by up to 4-fold the expression of matrix metalloproteinase by Jurkat-T-4 cells, but not Jurkat-T-2 cells, as assessed by cleavage of [(3)H]-type IV human collagen in the Matrigel. Enhancement of matrix metalloproteinase-dependent trans-Matrigel migration of Jurkat-T cells by the chemokine RANTES was suppressed by anti-Edg-2 R Abs, but was stimulated by anti-Edg-4 R Abs. The opposite effects of Edg-2 and Edg-4 LPA receptors on trans-Matrigel migration and some other T cell functions provide receptor-selective mechanisms for regulation of T cell recruitment and immune contributions.

Ionization mechanism of oligonucleotides in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The ionization of nucleosides in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was systematically investigated using adenine (A), thymine (T), guanine (G) and cytosine (C) with several common matrices. Experimental results of the protonation and deprotonation of the bases of A, T, G and C in the matrices 2,5-dihydroxybenzoic acid (2,5-DHB), alpha-cyano-4-hydroxycinnamic acid (alpha-CHCA) and 3-hydroxypicolinic acid (3-HPA) provide an insight into the ionization mechanism of oligonucleotides in MALDI. It was found that the low ion signal from DNA in poly-G in MALDI as reported in earlier work could be attributed to the fact that the base of G is difficult to ionize. Our results suggest that the ionization of DNA in MALDI is dominated by the protonation and deprotonation of bases and it is basically independent of the backbone of DNA. Both the protonation and deprotonation are strongly structure dependent. The protonation is dominated by pre-protonation before laser ablation, while the deprotonation is controlled by the thermal reaction.

Microbiology of the 'G-bacteria' in activated sludge

This review discusses a group of bacteria, the 'G-bacteria', which have a distinctive morphology of cocci in tetrads, sheets or clusters, that are seen in large numbers in many activated sludge biomass samples. Isolates of 'G-bacteria' that have been grown axenically are phylogenetically diverse. The Gram-negative members include several alpha- and beta-proteobacteria, among which is the genus Amaricoccus, while the Gram-positive 'G-bacteria' contain several members of the actinobacteria. It is probable that other, as yet uncharacterized, 'G-bacteria' exist in activated sludge. The hypothesis that these 'G-bacteria' are detrimental to the process of enhanced biological phosphate removal by competing for substrates anaerobically with the phosphate-accumulating bacteria in such systems, based as it is largely on mixed-culture studies, receives little support from studies using those available in pure culture. The evidence on which these conclusions are founded is discussed, as are the arguments used to explain why these 'G-bacteria' all appear to thrive under conditions found in certain activated sludge systems.

Altered expression and functional profile of lysophosphatidic acid receptors in mitogen-activated human blood T lymphocytes

Lysophosphatidic acid (LPA) from platelets and mononuclear phagocytes regulates T cell functions through endothelial differentiation gene-encoded G protein-coupled receptors (Edg Rs). Human blood unactivated CD4+ T cells express predominant ly Edg-4 LPA R over marginal levels of Edg-2 LPA R, as assessed by semiquantitative PCR and Western blots. After mitogen activation, the CD4+ T cells express Ed g-2 Rs at approximately one half the level of Edg-4 Rs. Secretion of IL-2 by unactivated Edg-4 R-predominant CD4+ T cells incubated with anti-CD3 plus anti-CD28 antibodies was suppressed significantly and by up to 60% by 10-10 M to 10-6 M LPA, whereas secretion of IL-2 by mitogen-activated Edg-2 R and Edg-4 R codominant CD4+ T cells was enhanced by up to twofold by the same concentrations of LPA. The possibility that the two Edg Rs transduce different LPA signals to CD4+ T cells was supported by findings that IL-2 secretion was inhibited by mouse anti-Edg-4 R monoclonal antibody, but enhanced by mouse anti-Edg-2 R monoclonal antibody. The separate effects of each LPA R were studied in Jurkat T cell transfectants expressing principally human Edg-2 Rs (Jurkat-T-2) or Edg-4 Rs (Jurkat-T-4) and stimulated with anti-CD3 plus phorbol myristate acetate. LPA and anti-Edg-4 R antibody suppressed IL-2 secretion by stimulated Jurkat-T-4 cells, whereas LPA and anti-Edg-2 R antibody enhanced IL-2 secretion by stimulated Jurkat-T-2 cells. Activation-induced alterations in the relative levels of Edg-2 and -4 Rs on CD4+ T cells thus reverse the effects of LPA on T cell receptor-stimulated generation of IL-2.

[Dynamic changes of respiration pathway and active oxygen levels in subcultured tobacco callus]

During the growth and senescence of tobacco callus, the total respiration rate showed two peaks on the 11th and 19th day, respectively. The development and operation of alternative pathway increased gradually, reached the maximum between two respiration peaks, and then declined in the following days, but the cytochrome pathway was still as a main electron transport pathway consistently. Analysis on the levels of active oxygen species during the growth and senescence process in tobacco callus suggested that H2O2 and O2.- were involved in some way in the induction of the development and operation of the alternative pathway, but the increase of production rate of OH might suppress both the development and operation of the alternative pathway, which were enhanced by H2O2 and O2.- respectively. These results were further proved by the use of active oxygen scavengers. The possible participation of the alternative pathway enhanced by active oxygen in the initial senescence process was discussed.

[Dynamics of respiration pathway in transgenic salt-tolerant wheat and its receptor under salt stress]

Using transgenic salt-tolerant wheat 89122 and its receptor Longchun 13 as test material, the dynamic changes of respiration pathway of wheat seedlings at different salt concentration were studied. The appearance of salt respiration was later in 89122 than in Longchun 13. The changes of Valt and rho Valt of both varieties had different patterns during salt stress process. Valt was suppressed by high salt levels, but could be induced by low salt levels in Longchun 13. The rho Valt and rho' Vcyt of two varieties were cooperatively regulated with each other to adapt to salt stress, and rho' Vcyt was the main electron transport pathway. The possible physiological roles of cyanide-resistant respiration were also discussed. It was suggested that the operation intensity of cyanide-resistant respiration could serve as a physiological index of plant salt-tolerance.

Cellular gangliosides promote growth factor-induced proliferation of fibroblasts

Cell surface gangliosides have been proposed as modulators of transmembrane signaling. In this study, we used two complementary approaches to investigate the function of cellular gangliosides in the response of mammalian fibroblasts to growth factors. First, inhibition of glucosyl ceramide synthase by a new specific inhibitor of d-l-threo-1-phenyl-2-hexadecanoylamino-3 -pyrrolidino-1-propanol-HC l (glucosylceramide synthase), which depletes cellular gangliosides at a concentration of 1 microm without causing an increase in ceramide levels, blocked epidermal growth factor-stimulated proliferation of fibroblasts. Similarly, responses to several other growth factors that activate receptor tyrosine kinases, including fibroblast growth factor, insulin-like growth factor-I, and platelet-derived growth factor, were inhibited by 50-100%. Conversely, enrichment of cellular gangliosides by preincubation of the mouse and human fibroblasts with exogenously added gangliosides enhanced growth factor-elicited cell proliferation. Novel findings of this study, distinguishing it from previous similar studies, include differential effects of preincubation versus continuous incubation of cells with gangliosides on growth factor-dependent cell proliferation and the growth factor-like action of NeuNAc alpha 2-3Gal beta 1-3GalNAc beta 1-4(NeuNAc alpha 2-3)Gal beta 1-4Glc beta 1-1Cer when cells are pretreated with the ganglioside.

Structural and immunological characteristics of a 28-kilodalton cruzipain-like cysteine protease of Paragonimus westermani expressed in the definitive host stage

A complete cDNA sequence encoding a 28-kDa cruzipain-like cysteine protease of adult Paragonimus westermani, termed Pw28CCP, was isolated from an adult cDNA library. The cDNA contained a single open reading frame of 975 bp encoding 325 amino acids, which exhibited the structural motif and domain organization characteristic of cysteine proteases of non-cathepsin Bs including a hydrophobic signal sequence, an ERFNIN motif, and essential cysteine residues as well as active sites in the mature catalytic region. Analysis of its phylogenetic position revealed that this novel enzyme belonged to the cruzipain-like cysteine proteases. The sequence of the first 13 amino acids predicted from the mature domain of Pw28CCP was in accord with that determined from the native 28-kDa enzyme purified from the adult worm. Expression of Pw28CCP was observed specifically in juvenile and adult worms, with a location in the intestinal epithelium, suggesting that this enzyme could be secreted and involved in nutrient uptake and immune modulation. The recombinant protein expressed in Escherichia coli was used to assess antigenicity by immunoblotting with sera from patients with active paragonimiasis and from those with other parasitic infections. The resulting sensitivity of 86.2% (56 of 65 samples) and specificity of 98% (147 of 150 samples) suggest its potential as an antigen for use in immunodiagnosis.

[Pharmacological studies of trilex on treatment of pharyngitis]

Trilex consisted of three species: Ilex latifolia, Ilex asprella and Ilex rotunda. Trilex had the antipyretic effects, decreased the rat body temperature about 0.8 degree C on yeast induced hyperthermia. Trilex could obviously enhance the threshold of hot plate induced pain in mice. The maximum threshold increased 43.8%. Trilex could also inhibit acetic acid induced inflammatory ooze in mice abdominal cavity. The inhibitory rate was 34.8%. These results showed that trilex had antipyretic, analgesic and anti-inflammatory effects. It could be used to treat acute and chromic pharyngitis.

[Factors affecting transformation of Agrobacterium tumefaciens and their application on cereals]

Agrobacterium tumefaciens mediated genetic transformation is the method most widely used in plant transformation. How to improve its transformation efficiency and extend its host range to include most cereals is what people concern about. There are many factors that influence the transformation efficiency, including the wounding response of plants, attachment of bacteria, induction of virulent gene, DNA repair and replication activity of plant cells, state of explant, etc. Recent research has proved that cerelas can be transformed effectively by A. tumefaciens under suitable conditions. This paper reviewed the recent progress in the two aspects.

Pedicle morphology in thoracic adolescent idiopathic scoliosis: is pedicle fixation an anatomically viable technique?

STUDY DESIGN

A radiographic study of thoracic pedicle anatomy in a group of adolescent idiopathic scoliosis (AIS) patients.

OBJECTIVE

To investigate the anatomic constraints of the thoracic pedicles and determine whether the local anatomy would routinely allow pedicle screw insertion at every level.

SUMMARY OF BACKGROUND DATA

In spite of the clinical successes reported with limited thoracic pedicle screw-rod constructs for thoracic AIS, controversy exists as to the safety of this technique.

MATERIAL AND METHODS

Twenty-nine patients with right thoracic AIS underwent preoperative thoracic CT scans and plain radiographs. Anatomic parameters were measured from T1 to T12.

RESULTS

Information on 512 pedicles was obtained. The transverse width of the pedicles from T1 through T12 ranged from 4.6-8.25 mm. The medial pedicle to lateral rib wall transverse width from T1 through T2 ranged from 12.6 to 17.9 mm. Measured dimensions from the CT scans showed the actual pedicle width to be 1-2 mm larger than would have been predicted from the plain radiographs. Age, Risser grade, curve magnitude, and the amount of segmental axial rotation did not correlate with the morphology or size of the thoracic pedicles investigated. In no case would pedicle morphology have precluded the passage of a pedicle screw.

CONCLUSION

Based on the data identified in this group of adolescent patients, it is reasonable to consider pedicle screw insertion at most levels and pedicle-rib fixation at all levels of the thoracic spine during the treatment of thoracic AIS.

Prospective pulmonary function evaluation following open thoracotomy for anterior spinal fusion in adolescent idiopathic scoliosis

STUDY DESIGN

Prospective study.

OBJECTIVES

To prospectively evaluate sequential pulmonary function tests (PFTs) at a minimum 2-year follow-up after an open anterior spinal fusion (ASF) with instrumentation for thoracic AIS.

SUMMARY OF BACKGROUND DATA

Anterior spinal fusion with instrumentation is currently undergoing evaluation as an alternative to posterior spinal fusion (PSF) for thoracic adolescent idiopathic scoliosis (AIS). However, the effect of an open thoracotomy on pulmonary function in these patients is unknown.

METHODS

Fifty-one patients with thoracic AIS with an average age of 15+0 (range 11+2 to 20+5) had PFTs consisting of volume (FVC), flow (FEV-1), and total lung capacity (TLC). Parameters were obtained preoperatively, and at 3 months, 1 year, and a minimum 2-year follow-up. All patients had a single or double open thoracotomy with the diaphragm kept intact. Fusion levels ranged from T4 (most proximal) to L1 (most distal). The average preoperative thoracic coronal Cobb measurement was 53 degrees (range 38 degrees to 80 degrees ), and the average postoperative coronal measurement was 24 degrees (range 7 degrees to 49 degrees ). The average preoperative thoracic sagittal kyphosis (T5-T12) averaged 22 degrees (range 10 degrees to 58 degrees ), and the average postoperative sagittal kyphosis measured 29 degrees (range 7 degrees to 67 degrees ).

RESULTS

There was a significant decline (P< or =0.05) in PFT absolute values (L) of 19%-FVC, 15%-FEV-1, and 11%-TLC at 3 months postoperatively with subsequent improvement and no statistical difference between preoperative and 2-year postoperative values. When evaluating percent predicted values, there was a statistical decline (P< or =0.05) at 3 months postoperatively averaging 19% FVC, 14% FEV-1, and 12% TLC. These values returned to within 94% to 96% of baseline by the 2-year follow-up visit, but were still statistically less than the preoperative values (P</=0.05).

CONCLUSIONS

Pulmonary function following thoracotomy with ASF with instrumentation demonstrated a significant decline of 3-month postoperative PFT values, but returned to preoperative baseline absolute values (L) by the 2-year follow-up visit. The percent predicted values returned to within 95% of baseline 2 years postoperatively. Scoliosis surgeons should be aware of these findings when deciding upon the approach (anterior versus posterior) utilized for thoracic AIS.

Differential expression of the 27 kDa cathepsin L-like cysteine protease in developmental stages of Spirometra erinacei

The 27 kDa cathepsin L-like cysteine protease of Spirometra erinacei plerocercoid is known to play an important function in tissue penetration, nutrient uptake and immune modulation in human sparganosis. In the present study, the expression of this enzyme was examined at different developmental stages of S. erinacei including immature egg, coracidium, plerocercoid in tadpole and rat, and adult. Proteolytic activity against carboxybenzoyl-phenylalanyl-arginyl-7-amino-4-methylcoumarin was detected in the extracts of coracidia and plerocercoid while no activity was observed in those of immature egg and adult. The specific activity in coracidial extracts was lower than that in the plerocercoid. Reverse transcription-polymerase chain reaction and Northern blot analysis demonstrated that the gene was expressed in the coracidium and plerocercoid but not in immature egg and adult. These results suggest that the 27 kDa cysteine protease is only expressed in the stages involving active migration of the parasite in the host tissue.

IgG antibody responses in early experimental sparganosis and IgG subclass responses in human sparganosis

Antigenic components in the crude extracts of Spirometra mansoni plerocercoid were analyzed in early experimental infections and in IgG subclass observed in clinical sparganosis. By IgG immunoblot, sera obtained serially from experimental mice, fed 5 spargana each, were reacted with the crude extracts. Protein bands at 36-26 kDa and 103 kDa showed positive reactions since two weeks after infection. In a differential immunoblot, in which a monospecific antibody against sparganum chymase at 36 kDa was pre-treated, the reactions at 36-26 kDa disappeared, indicating that the sparganum chymase and its degradation products invoked IgG antibody reactions. When 69 patients sera of human sparganosis were examined for their IgG subclass responses, IgG4 levels showed the highest reaction which was followed by IgG1. The IgG4 antibody also reacted mainly with 36-31 kDa protease. These results indicate that 36 kDa chymase of S. mansoni plerocercoid is the main antigenic component inducing IgG antibody response in early stage of experimental sparganosis and for specific IgG subclass reactions in human sparganosis.

The 10 kDa protein of Taenia solium metacestodes shows genus specific antigenicity

Genus specific antigenicity of the 10 kDa protein in cyst fluid (CF) of Taenia solium metacestodes was demonstrated by comparative immunoblot analysis. When CFs from taeniid metacestodes of T. saginata, T. solium, T. taeniaeformis and T. crassiceps were probed with specific monoclonal antibody (mAb) raised against 150 kDa protein of T. solium metacestodes, specific antibody reactions were observed in 7 and 10 kDa proteins of T. solium and in 7/8 kDa of T. saginata, T. taeniaeformis and T. crassiceps. The mAb did not react with any protein in hydatid fluid of Echinococcus granulosus and E. multilocularis. This result revealed that the 10 kDa peptide of T. solium metacestodes and its equivalent proteins of different Taenia metacestodes are genus specific antigens that are shared among different Taenia species.

Persisting antibody reaction in paragonimiasis after praziquantel treatment is elicited mainly by egg antigens

Antibody responses in serum and cerebrospinal fluid (CSF) samples from patients with active and chronic paragonimiasis and in sera from patients on whom follow-up studies were done after praziquantel treatment were analyzed using antigens of Paragonimus westermani prepared from eggs, metacercariae, juveniles of 4- and 7-week old, adult worms and recombinant protein of 28 kDa cruzipain-like cysteine protease (rPw28CCP). The patient sera/CSFs of active and chronic paragonimiasis revealed strong antibody reactions against the crude extracts of 4- and 7-week old juveniles as well as against those from egg and adult. rPw28CCP also showed specific reaction to the sera with active paragonimiasis. After the treatment, levels of specific antibodies in the sera gradually decreased to negative range in most patients. In some cases with persisting high antibody levels, however, the reactions at 27 kDa egg protein were sustained throughout the observation period of 34 months. The reactions at 35 and 32 kDa in adult extract and rPw28CCP disappeared rapidly after the treatment. Persistent antibody reactions even after successful treatment are provoked by continuous antigenic challenge from eggs which were not resolved by treatment.

Cutting edge: differential constitutive expression of functional receptors for lysophosphatidic acid by human blood lymphocytes

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) from platelets and macrophages mediate T cell functions. Endothelial differentiation gene-encoded G protein-coupled receptors (Edg Rs) are specific for S1P (Edg-1, -3, -5, and -8 Rs) and LPA (Edg-2, -4, and -7 Rs). Human T cell tumors express many Edg Rs for both LPA and S1P. In contrast, human blood CD4+ T cells express predominantly Edg-4, and CD8+ T cells show only traces of Edg-2 and -5, by quantification of mRNA and Edg R Ags. LPA at 10-10-10-6 M suppressed significantly the secretion of IL-2 from anti-CD3 plus anti-CD28 Ab-challenged CD4+ T cells, but not CD8+ T cells. Monoclonal anti-Edg-4 R Ab, like LPA, suppressed stimulated IL-2 secretion from CD4+ T cells, but not CD8+ T cells. Constitutive expression of Edg-4 by CD4+, but not CD8+, human T cells accounts for differential functional responsiveness of the T cell subsets to LPA.

Paragonimus westermani: a cytosolic glutathione S-transferase of a sigma-class in adult stage

We purified cytosolic glutathione S-transferase (GST) of adult Paragonimus westermani monitoring its activity with 1-chloro-2,4-dinitrobenzene (CDNB). The enzyme was purified 18.4-fold to electrophoretic homogeneity with 21% recovery rate through a three-step procedure. The purified enzyme (Pw28GST) has a subunit molecular weight of 28 kDa with an isoelectric point at 4.6. Monoclonal antibody (anti-Pw28GST) against Pw28GST did not cross-react with GSTs from other helminths. cDNA library was constructed in lambdaZAP II bacteriophage and screened with anti-Pw28GST. The corresponding gene containing a single open reading frame of 804 bp encoded 211 amino acids. The predicted amino acid sequence exhibited a higher homology with catalytic domain near N-terminus of class sigma GSTs (58%) than with schistosome 28-kDa GSTs (45-41%) or with class sigma GSTs themselves (33-31%). The sequence contained both Tyr-6 and Tyr-10 that are highly conserved in mammalian and helminth GSTs. The apparent K(m) value of a recombinant enzyme was 0.78 mM. Both native and recombinant enzymes showed the highest activity against CDNB, relatively weak activity against ethacrynic acid and reactive carbonyls, and no activity against epoxy-3-(p-nitrophenoxy)-propane. The activities were inhibited by bromosulfophthalein, cibacron blue, and albendazole, but not by praziquantel. These findings indicate that adult P. westermani has a class sigma GST.

The winged-helix/forkhead protein myocyte nuclear factor beta (MNF-beta) forms a co-repressor complex with mammalian sin3B

Winged-helix/forkhead proteins regulate developmental events in both invertebrate and vertebrate organisms, but biochemical functions that establish a mechanism of action have been defined for only a few members of this extensive gene family. Here we demonstrate that MNF (myocyte nuclear factor)-beta, a winged-helix protein expressed selectively and transiently in myogenic precursor cells of the heart and skeletal muscles, collaborates with proteins of the mammalian Sin3 (mSin3) family to repress transcription. Mutated forms of MNF-beta that fail to bind mSin3 are defective in transcriptional repression and in negative growth regulation, an overexpression phenotype revealed in oncogenic transformation assays. These data extend the known repertoire of transcription factors with which mSin3 proteins can function as co-repressors to include members of the winged-helix gene family. Transcriptional repression by MNF-beta-mSin3 complexes may contribute to the co-ordination of cellular proliferation and terminal differentiation of myogenic precursor cells.

Enhancement of ultraviolet photorefraction in highly magnesium-doped lithium niobate crystals

We investigate UV photorefraction in Mg-doped LiNbO(3) crystals. Strong UV photorefraction is achieved in highly Mg-doped LiNbO(3) crystals with high two-wave mixing gain, fast response, and low noise. It is also demonstrated experimentally that so-called damage-resistant dopants such as Mg are damage resistant only in the visible and that they will enhance photorefraction in the UV.

Distinctive expression and functions of the type 4 endothelial differentiation gene-encoded G protein-coupled receptor for lysophosphatidic acid in ovarian cancer

Endothelial differentiation gene (edg)-encoded G protein-coupled receptors (Edg Rs)-1, -3, and -5 bind sphingosine 1-phosphate (S1P), and Edg-2 and -4 bind lysophosphatidic acid (LPA). Edg Rs transduce signals from LPA and S1P that stimulate ras- and rho-dependent cellular proliferation, enhance cellular survival, and suppress apoptosis. That high levels of LPA in plasma and ascitic fluid of patients with ovarian cancer correlate with widespread invasion suggested the importance of investigating expression and functions of Edg Rs in ovarian cancer cells (OCCs) as compared with nonmalignant ovarian surface epithelial cells (OSEs). Analyses of Edg Rs by semiquantitative reverse transcription-PCR, a radioactively quantified variant of PCR, and Western blots developed with monoclonal antibodies showed prominent expression of Edg-4 R in primary cultures and established lines of OCCs but none in OSEs. In contrast, levels of Edg-2, -3, and -5 were higher in OSEs than OCCs. LPA stimulated proliferation and signaled a serum response element-luciferase reporter of immediate-early gene activation in OCCs but not OSEs, whereas S1P evoked similar responses in both OSEs and OCCs. Pharmacological inhibitors of Edg R signaling suppressed OCC responses to LPA. A combination of monoclonal anti-Edg-4 R antibody and phorbol myristate acetate, which were inactive separately, evoked proliferative and serum response element-luciferase responses of OCCs but not OSEs. Thus the Edg-4 R may represent a distinctive marker of OCC that transduces growth-promoting signals from the high local concentrations of LPA characteristic of aggressive ovarian cancer.

A recombinant 10-kDa protein of Taenia solium metacestodes specific to active neurocysticercosis

Neurocysticercosis (NCC) is an important cause of neurological disease worldwide. A 10-kDa antigen of Taenia solium metacestodes (TsMs) has been shown to be specific for immunodiagnosis of NCC. Screening of a TsM complementary DNA (cDNA) library isolated a cDNA encoding this protein. The cloned cDNA contained a 258-bp complete open-reading frame that encodes an 86-amino acid polypeptide with a calculated molecular weight of 9582 Da. It showed 73% homology with a 10-kDa antigen of T. crassiceps. The recombinant protein was expressed bacterially as a fusion protein at a high level. In immunoblot with recombinant protein, 97% (184/190) of sera from patients with active NCC showed strong reactivity, whereas 14% (4/29) of those from patients with chronic calcified NCC reacted weakly. In 180 sera from other patients with parasitic infections and from normal controls, it showed 98% specificity. A single recombinant TsM antigen has a high potential for serological differentiation of active NCC.

Dual mechanisms for lysophospholipid induction of proliferation of human breast carcinoma cells

Endothelial differentiation gene-encoded G protein-coupled receptors (Edg Rs) Edg-1, Edg-3, and Edg-5 bind sphingosine 1-phosphate (S1P), and Edg-2 and Edg-4 Rs bind lysophosphatidic acid (LPA). LPA and S1P initiate ras- and rho-dependent signaling of cellular growth. Cultured lines of human breast cancer cells (BCCs) express Edg-3 > Edg-4 > Edg-5 > or = Edg-2, without detectable Edg-1, by both assessment of mRNA and Western blots with rabbit and monoclonal mouse anti-Edg R antibodies. BCC proliferation was stimulated significantly by 10(-9) M to 10(-6) M LPA and S1P. Luciferase constructs containing the serum response element (SRE) of growth-related gene promoters reported mean activation of BCCs by LPA and S1P of up to 85-fold. LPA and S1P stimulated BCC secretion of type II insulin-like growth factor (IGF-II) by 2-7-fold, to levels at which exogenous IGF-II stimulated increased proliferation and SRE activation of BCCs. All BCC responses to LPA and S1P were suppressed similarly by pertussis toxin, mitogen-activated protein kinase kinase inhibitors, and C3 exoenzyme inactivation of rho, suggesting mediation by Edg Rs. Monoclonal anti-IGF-II and anti-IGFR1 antibodies suppressed proliferation and SRE reports of BCCs to LPA and S1P by means of up to 65%. Edg Rs thus transduce LPA and S1P enhancement of BCC growth, both directly through SRE and indirectly by enhancing the contribution of IGF-II.

Lens epithelium and fiber Na,K-ATPases: distribution and localization by immunocytochemistry

PURPOSE

To use immunofluorescence and immunogold techniques to identify the catalytic subunits of the Na,K-ATPases of the lens and to determine their location in the cells of the epithelium and cortex of bovine and human lenses.

METHODS

Frozen sections of capsulated and decapsulated bovine and human lenses were prepared, blocked, and treated with affinity-purified polyclonal rabbit antibodies to the Na,K-ATPase catalytic subunit isoforms with subsequent treatment with fluorescein isothiocyanate-labeled goat anti-rabbit IgG and visualization of the fluorescence by light microscopy. An immunogold-labeled goat anti-rabbit IgG was used to detect, by electron microscopy, the binding of the same affinity-purified polyclonal antibodies to thin sections of decapsulated lenses that had been fixed and embedded in Lowicryl K4M. The results were confirmed by staining of western blot analysis of sodium dodecyl sulfate-polyacrylamide gel separations of enriched membrane preparations from bovine and human lenses.

RESULTS

The three common catalytic subunits of the Na,K-ATPases are present in the plasma membranes of lens epithelium, lens fibers, or both. The data indicate a polarized distribution of the alpha1 and alpha3 catalytic subunit isoforms in central epithelium. In the cortical fibers, the alpha2 isoform is present around the interdigitations. The alpha3 isoform is found in the interdigitation-free regions of human cortical fibers.

CONCLUSIONS

This unique distribution of Na,K-ATPases precludes the popular pump-leak model for lens monovalent cation homeostasis. The functional significance of the distribution of Na,K-ATPases in the lens epithelium and superficial fibers is currently under investigation.

Ligand binding on ladder lattices

The ligand binding problems on two-dimensional ladders, which model many important binding phenomena in molecular biology, are studied in details. The model is represented by four parameters, the interactions between ligands when bound to adjacent sites on opposite legs of the ladder (tau), the interactions between bound ligands in the longitudinal direction of the ladder (sigma), the number of binding sites that are covered by a bound ligand (m), and the intrinsic binding constant (K). The partition functions of ring ladders are approached with the transfer matrix method. A general relation is derived which connects the partition function of a linear ladder with that of a ring ladder. The results obtained apply to the general situation of multivalent binding, in which m>1. Special attention is paid to the case where the ligand covers one site (m=1). In this case explicit formulas are given for the partition functions of ring and linear ladders. Closed-form expressions are obtained for various properties of the system, including the degree of binding (theta), the midpoint in the binding isotherm (1/square root(tau sigma)), the initial and end slopes of the Scatchard plots (2sigma + tau - 4 and -sigma2 tau, respectively). From these closed-form formulas, sigma and tau may be extracted from experimental data. The model reveals certain features which do not exist in one-dimensional models. Using the general method discussed in [1], the recurrence relation is found for the partition functions. The analytical solution found for this model provides test cases to verify the numerical results for more complex two-dimensional models.

Age-dependent infectivity of orally transferred juvenile Fasciola hepatica

Juvenile Fasciola hepatica is infective when administered orally. To determine whether the age of juveniles is a factor in infectivity by oral transfer, experimental mice were challenged orally with immature F. hepatica that had been grown in donor mice for 12, 14, 16, and 18 days. Experimental mice were examined for infections 12 16 days after the oral transfers. The infection success in experimental mice decreased with the age of juveniles. The worm recovery also decreased according to the age of juveniles. None of the juveniles was infective when grown for longer than 11 days. Once infected, orally transferred worms continued to grow. Juvenile age was a significant factor in determining the infectivity of orally transferred juvenile F. hepatica.