The nicotinic acetylcholine receptor agonist ABT-594 increases FGF-2 expression in various rat brain regions

The present experiments were designed to extend previous work showing that acute intermittent (-)nicotine treatment upregulates the level of fibroblast growth factor-2 (FGF2) mRNA in several rat brain regions, by the use of the nicotinic acetylcholine receptor (nAChR) agonist ABT-594 with preferential selectivity for the alpha4beta2 nAChR subtype. ABT594 treatment led to a well-defined temporal and regional upregulation of FGF-2 mRNA. A double labelling analysis showed that the up-regulation of FGF-2 mRNA involves both neuronal and non-neuronal cells. The effects of ABT-594 on FGF-2 expression were antagonized by the preferential alpha4beta2 antagonist dihydrobetaerythroidine (DHbetaE), but not by alpha7 antagonist methyllycaconitine (MLA). In conclusion, FGF-2 mRNA levels can be increased in several brain regions upon alpha4beta2 nAChR activation, suggesting a therapeutic significance in neurodegenerative disorders.

The nicotinic acetylcholine receptor agonist (+/-)-epibatidine increases FGF-2 mRNA and protein levels in the rat brain

In a previous work, we showed that acute intermittent nicotine treatment up-regulates the level of fibroblast growth factor-2 (FGF-2) mRNA in brain regions of tel- and mesencephalon of rats suggesting that neuroprotective effect of (-)nicotine may, at least in part, involve an activation of the neuronal FGF-2 signalling. The present experiments were designed to extend the study on the nicotinic receptor mediated up-regulation of FGF-2 mRNA levels to the use of the potent nicotinic acetylcholine receptor (nAChR) agonist (+/-)-epibatidine. The (+/-)-epibatidine treatment led to a strong and long lasting up-regulation of FGF-2 mRNA expression in the cerebral cortex, in the hippocampal formation, in the striatum and in the substantia nigra. This FGF-2 mRNA induction, already statistically significant at 4 h, peaked at 12 h from treatment and was only partially returned towards normal levels at 48 h, the last time point examined. Using Western blot analysis it was found that the epibatidine-induced upregulation of FGF-mRNA is accompaned by an increase of FGF-2 protein level at the 20-h time-interval. These (+/-)-epibatidine effects on FGF-2 expression were antagonized by the non-competitive nAChR antagonist mecamylamine, indicating an involvement of nicotinic receptors. In the same brain areas examined, no changes were observed in the fibroblast growth factor receptor-1 (FGFR-1) mRNA levels, in brain-derived neurotrophic factor (BDNF) and in glial cell line-derived neurotrophic factor (GDNF) mRNA levels. In view of the neurotrophic function of FGF-2, these results, together with previous ones, could further help to understand the molecular mechanisms mediating the previously observed neuroprotective effects of (-)nicotine.

Integrin alphavbeta3-RGDS interaction mediates fibrin-induced morphological changes of glomerular endothelial cells

BACKGROUND

In our previous studies, we found that intraglomerular deposition of fibrin and its metabolites was related to glomerular sclerosis and reduced renal function. It has been reported that both overlying and underlying fibrin may induce specific morphological changes of cultured endothelial cells from large blood vessels. The dependency of these morphological changes on the integrin alphavbeta3-arginyl-glycyl-aspartyl-serine (RGDS) interaction is still controversial. We hypothesized that glomerular endothelial cells (GECs) stimulated by fibrin might undergo morphological changes through an integrin alphavbeta3-RGDS interaction. Methods. In vitro studies were performed to examine the growing status of GECs stimulated by overlying and underlying fibrin gels in the presence or absence of the following: 50 microg/ml anti-alphavbeta3 integrin monoclonal antibody 23C6 or nonimmune mouse IgG, 1 mg/ml synthetic RGDS or arginyl-glycyl-glycyl-serine (RGGS) peptide, 10 mg/ml sodium heparin, 100 microg/ml cycloheximide, and 10 microM actinomycin D. Fast protein liquid chromatography (FPLC)-purified fibrinogen and the third to fifth passages of human GECs were also used in this study.

RESULTS

GECs developed capillary tube structure after 60 hours of culturing on fibrin gels, and GECs cultured on gelatin-coated plates displayed a monolayer of cobblestone-like cells in the presence or absence of 23C6 and synthetic RGDS peptide. Fibrin-induced capillary tube formation was promoted by 23C6 and inhibited by RGDS peptide, cycloheximide, and actinomycin D. Disorganization of the GEC monolayer was induced by overlying fibrin, but was not induced by overlying agarose gels and glass cover slips or culturing in fibrinogen, 0.05 NIH U/ml thrombin, fibrin supernatants, as well as in fibrin degradation products. Disorganization of GEC monolayer can be induced by both des-AA-fibrin and des-AABB-fibrin and was unaffected by heparin. Furthermore, both 23C6 and synthetic RGDS peptide prevented disorganization of GECs induced by overlying fibrin, whereas nonimmune mouse IgG, synthetic RGGS peptide, cycloheximide, and actinomycin D had no similar effect.

CONCLUSIONS

GECs cultured on fibrin gels may develop capillary structure spontaneously, and GECs covered by fibrin gels may undergo disorganization. Our data suggest that these GEC morphological changes are mediated by an integrin alphavbeta3-RGDS interaction.

NF-kappaB-mediated up-regulation of Bcl-x and Bfl-1/A1 is required for CD40 survival signaling in B lymphocytes

Activation of CD40 is essential for thymus-dependent humoral immune responses and rescuing B cells from apoptosis. Many of the effects of CD40 are believed to be achieved through altered gene expression. In addition to Bcl-x, a known CD40-regulated antiapoptotic molecule, we identified a related antiapoptotic molecule, A1/Bfl-1, as a CD40-inducible gene. Inhibition of the NF-kappaB pathway by overexpression of a dominant-active inhibitor of NF-kappaB abolished CD40-induced up-regulation of both the Bfl-1 and Bcl-x genes and also eliminated the ability of CD40 to rescue Fas-induced cell death. Within the upstream promoter region of Bcl-x, a potential NF-kappaB-binding sequence was found to support NF-kappaB-dependent transcriptional activation. Furthermore, expression of physiological levels of Bcl-x protected B cells from Fas-mediated apoptosis in the absence of NF-kappaB signaling. Thus, our results suggest that CD40-mediated cell survival proceeds through NF-kappaB-dependent up-regulation of Bcl-2 family members.

The effectiveness and safety of dorzolamide 2% in addition to multiple topical antiglaucoma medications

Dorzolamide is the first commercial topical carbonic anhydrase inhibitor approved by the Food and Drug Administration (FDA) for the treatment of glaucoma. In a prospective, open label, uncontrolled study on 245 glaucoma patients, dorzolamide significantly lowered the intraocular pressure at least 14% when used alone or in combination with one, two, or three other antiglaucoma medications over ten weeks. There were very few adverse reactions to dorzolamide. Dorzolamide is effective and safe when used alone or in combination with other topical antiglaucoma medications for the treatment of glaucoma.

[Antisense oligonucleotide attenuates renal tubulointerstitial injury in mice with unilateral ureteral obstruction]

OBJECTIVE

To inhibit the expression of ICAM-1 mRNA with the mouse ICAM-1 phosphorothioate antisense oligodeoxynucleotide (ASON) and to investigate the role of ICAM-1 in the pathophysialogical process of renal injury in unilateral ureteral obstruction (UUO) animal model.

METHODS

After unilateral ureteral ligation, the mice were treated with ICAM-1 ASON, which was injected intravenously at the dosage of 1 mg/kg/day every other day for one week. Other mice treated with control oligonucleotide or normal saline solution only were taken as controls. The expression of ICAM-1 protein and the number of Mac-1 positive cells were measured by immunohistochemical staining. The pathological changes of the obstructed kidney in the mice were analyzed by PAS-staining. Total RNA renal tissue was extracted for the analysis of the ICAM-1 mRNA by methods of Northern blotting.

RESULTS

The expression of ICAM-1 protein and the number of Mac-1 positive cells were reduced markedly in the obstructed kidneys of the mice treated with the ICAM-1 ASON(110 +/- 14 [symbol: see text]/mm2 vs 270 +/- 13 [symbol: see text]/mm2). The results of Northern blotting also showed marked decrease of the expression of ICAM-1 mRNA in the kidney of the mice after treatment with ICAM-1 ASON. There were marked inflammatory cells infiltration in the tubulointerstitium, markedly dilated tubules, and extraceliular matrix accumulation in the obstructed kidneys on the 7th day after UUO operation. The treatment of ICAM-1 ASON can alleviate the lesions of the obstructed kidney except for the dilation of the tubules. There was no difference in the body weight, liver weight, spleen weight, the level of BUN and SCr, the level of GPT as well as the urine protein of the mice treated with ICAM-1 ASON, compared with those in control Oligodeoxynucleotide-treated and saline-treated mice.

CONCLUSIONS

ICAM-1 is a very important factor in the pathogenesis of the UUO animal model. The mouse ICAM-1 ASON has therapeutic effects on the injury of the obstructed kidney without apparent side effects.

First hospital-admission rate as an epidemiological indicator for patients with multiple sclerosis in Stockholm, 1984-1993

OBJECTIVES

To evaluate the first hospital-admission patients with multiple sclerosis (MS) in the population.

MATERIAL AND METHODS

By using the data from hospital discharge registry of MS diagnosis in Stockholm during 1984-1993, we calculated rates of first hospital-admission patients with MS in the population and evaluated the temporal trend of the rates during the study period.

RESULTS

There were 719 first hospital-admission patients with MS corresponding to 1556 admissions. The mean age at the first admission was nearly the same for male patients (44.3 years, SD: 12.9) and for female patients (44.6 years, SD: 13.7). The mean annual rate of first hospital-admission patients with MS was 4.46 per 100,000 person-years. The sex rate ratio of first hospital-admission patients with MS between females and males was 2.19:1.

CONCLUSION

The first hospital-admission rate of MS could be used as an epidemiological indicator which is useful in planning of hospital service for MS patients.

Expression of neurotrophins, GDNF, and their receptors in rat thyroid tissue

Levels of mRNA for neurotrophins (brain-derived neurotrophic factor, BDNF; neurotrophin 3, NT-3; neurotrophin 4, NT-4) and their receptors (trkA, trkB, trkC) and for glial cell line-derived neurotrophic factor (GDNF) and its receptors (ret, GDNFR-alpha) were measured in rat thyroid tissue by ribonuclease protection assays. In thyroid tissue the NT-3 mRNA level was threefold lower and the NT-4 mRNA level sixfold higher than those detected in adult rat hippocampus, while BDNF mRNA was undetectable. Very low levels of mRNA for truncated trkB and trkC receptors and no catalytic trkA, trkB or trkC were found. In conclusion NT-3 and NT-4, but not the corresponding functional receptors, are expressed in the thyroid tissue. Therefore, it is unlikely that these factors serve a direct local autocrine or paracrine function in thyroid cell types, and a target-derived mode of action on neurons innervating the thyroid tissue is suggested. An opposite result has been found for the neurotrophic factor GDNF: thyroid tissue showed a high level of transcripts for the GDNF receptor subunits (GDNFR-alpha and Ret), while GDNF mRNA was undetectable. The in situ hybridization analysis of GDNFR-alpha and ret mRNA revealed an interesting difference in the cell distribution of these transcripts: ret mRNA is selectively expressed in a subpopulation of cells scattered in the follicular epithelium and in the interfollicular spaces, while GDNFR-alpha expression is more homogeneous and widespread, including the more abundant cell type of the thyroid gland: the follicular cell. Double-labeling in situ hybridization/immunocytochemistry experiments, with a specific marker (calcitonin), showed that parafollicular cells express ret but not GDNFR-alpha. This differential distribution of the GDNF receptor components (GDNFR-alpha and ret) may reflect a peculiar biological role in intercellular communication in the thyroid gland.

Codon usage in Plasmodium vivax nuclear genes

Codon usage in Plasmodium vivax nuclear genes was analysed and compared with that in Plasmodium falciparum nuclear genes. Preferred codons were determined for P. vivax. Unlike P. falciparum, P. vivax genes are about 15% less A+T rich in the coding regions, with no obvious A+T bias at the third position of the codons. The amino-acid composition of P. vivax gene products is also different from that of P. falciparum. These results provide valuable information to facilitate gene cloning as well as expression and transfection studies for P. vivax.

Tissue tropism, transmission and expression of foreign genes in vivo in midgut symbionts of tsetse flies

Tsetse flies (Diptera: Glossinidae) harbour three different symbiotic organisms in addition to the pathogenic African trypanosomes they transmit. The two gut-associated symbionts (primary, P; secondary, S) are enteric and are nutritionally required, whereas the third microorganism Wolbachia (family Rickettsiaceae) affects the reproductive biology of the insects it infects. The bacteriome-associated P-symbiont (Wigglesworthia glossinidia) displays a concordant phylogeny with its host tsetse species, whereas midgut S-symbionts characterized from distant tsetse have identical 16S rDNA sequences and therefore may either represent recent independent acquisitions or horizontal transfer between species. The S-symbionts have been cultured in vitro and a genetic transformation system has been developed. Here we report on their density and tissue tropism in different species (G. m. morsitans, G. p. palpalis, G. austeni and G. brevipalpis) and on their maternal route of transmission to tsetse progeny. Using a bacterium-specific PCR-assay, the S-symbionts were found primarily in the midgut, haemolymph, milk gland and in G. palpalis also in salivary glands of teneral flies. In older flies these infections were found to spread to other tissues including muscle, testes and fat body. The S-symbionts were transformed to express the marker gene product, Green Fluorescent Protein (GFP) in vitro. When the recombinant symbionts were introduced into the haemoceal of fertile female flies via intrathoracic microinjection, they were detected in the intrauterine progeny, indicating that haemolymph may provide a possible route for their transmission. The implications of these results for symbiont-host interactions and for transgenic strategies in tsetse are discussed.

[The experience of treatment of 7 cases of olfactory neuroblastoma]

OBJECTIVE

To improve the treatment result of olfactory neuroblastoma.

METHOD

Introduce the experience of treatment of 7 patients with this disease. Among these 7 cases, 2 of them were stage B while the others were stage C according to the system proposed by Kadish. 3 cases received radiotherapy alone, and 4 others received radiotherapy pre-operation. The radiation dose was 5000-7000 cGy. All the patients were followed-up until December 1997.

RESULT

5 cases are still alive, survival time are 20, 22, 23, 29 and 76 months respectively. The other 2 patients died with the survival time of 6 and 48 months respectively.

CONCLUSION

Radiotherapy seems effective in the treatment of olfactory neuroblastoma; the combination of chemo-radio-therapy is preferable for advanced or metastasis olfactory neuroblastoma. We extrapolate there are different subtypes on pathology in this tumor.

[Effects of sevoflurane on contractility of isolated thoracic aorta rings in rabbits]

The objective of this paper was to observe the effects of sevoflurane on isolated rabbit aortic rings and the mechanisms of the effects. Twenty-four vascular rings collected from different New Zealand rabbits were randomly divided into 4 groups: Group 1 endothelium-inact rings; Group 2 endothelium-denuded rings; Group 3 endothelium-intact rings plus indomethacin; Group 4 endothelium-denuded rings plus indomethacin. When stable active tension produced by phenylephrine (1 x 10(-6) mol.L-1) was obtained, sevoflurane was added into the tissue bath. The anesthetic gas was increased in 0.5% increments every 10 min until the 4% of sevflurane after which 5% was administered. In rings of Group 3 and Group 4, indomethacin (2.8 x 10(-5) mol.L-1) was added to the bath 10 min before the addition of sevoflurane. The results showed that sevoflurane relaxed all groups of rings dose-dependently and this action was non-endothelium dependent and indomethacin had no effect on it. It suggests that sevoflurane relaxes peripheral vessels perhaps by affecting vascular muscle directly.

stevor and rif are Plasmodium falciparum multicopy gene families which potentially encode variant antigens

Several multicopy gene families have been described in Plasmodium falciparum, including the var genes that code for the variant surface antigen PfEMP1, the stevor family of subtelomeric open reading frames and the rif interspersed repetitive elements. This report documents the chromosomal location of stevor genes, their transcription and characteristics of the deduced protein. On 14 chromosomes, 34 stevor copies were identified from the Dd2 parasite line. Most are in subtelomeric regions within 50 kb of the telomere. stevor genes are located close to var genes and rij. All stevor genes sequenced had two exons: a short exon 1 encoding a start codon and a transmembrane domain; exon 2 encoding for the remainder of the approximately 30 kDa protein and including two more transmembrane segments. A similar structure was found for copies of rif and its predicted protein. In both STEVOR and RIF proteins, a highly polymorphic region is predicted to be a loop on the outer side of the membrane. We propose that stevor and rif are members of a larger superfamily. The number of copies of stevor and rif, their location close to the var genes, their extreme polymorphism and the predicted structure of the proteins suggest that stevor and rif code for variant surface antigens.

Increased incidence of Guillain-Barré syndrome postpartum

We studied the relation between pregnancy and Guillain-Barré syndrome in the Swedish female population ages 15-49 years during the period 1978-1993. Person-based information from the national Hospital In-patient Registry on patients discharged with a diagnosis of Guillain-Barré syndrome was linked to data on pregnancy and delivery from the Swedish Medical Birth Registry. We validated coded Guillain-Barré syndrome diagnoses and the time periods of clinical onset for patients hospitalized with Guillain-Barré syndrome during pregnancy or during the first 90-day postpartum period. We compared the incidence of Guillain-Barré syndrome in women in different exposure categories related to pregnancy with that in women neither pregnant nor in the 90-day postpartum period. Poisson regression analysis yielded age-adjusted rate ratios of 0.89 [95% confidence interval (CI) = 0.52-1.53] for pregnant women, 1.37 (95% CI = 0.64-2.91) for women during the first 90 days, and 2.93 (95% CI = 1.20-7.11) during the first 30 days after delivery. Our results indicate that the risk of Guillain-Barré syndrome increases after delivery, particularly during the first 2 weeks postpartum.

ras1 and pat1 alleles interact to quantitatively and qualitatively alter conjugation in fission yeast

To identify novel components of ras1+ signalling in Schizosaccharomyces pombe, extragenic suppressors of the mating defect of ras1 effector mutants were isolated. A novel allele of pat1, pat1-e1, was isolated that increases the mating of ras1-D43E mutants to near wild-type levels but does not suppress the mating defect of ras1-I41M, ras1-Y37F, or ras1-Y45I mutants. This allele-specific suppression is not a characteristic of all pat1 alleles since pat1-3 and pat1-114 partially and equally suppress ras1-D43E and ras1-I41M mutants. Analysis of mating cultures showed that ras1-D43E and pat1-e1 interact to qualitatively alter the mating response. While pat1-e1 ras1-D43E cells were delayed in agglutination, cell-cycle delay, and mat1-Pm transcription, they induce mat1-Mc at the same time and mate more rapidly than other mating cultures. These results suggest that pheromone signalling, but not nutritional signalling, is delayed in pat1-e1 ras1-D43E cells. We hypothesize that this delay causes an elevated pheromone response and thus suppression of the mating defect of the ras1-D43E mutant by pat1-e1.

The effect of antiglaucoma drugs on rabbit aqueous humor proteins determined by gel electrophoresis

Previous studies indicate that there may be differences in the protein composition of the aqueous humor in normal and glaucomatous human eyes. These differences in protein composition and concentration may be due to the topical antiglaucoma medications used to treat glaucoma. These differences should be distinguished from any possible protein composition changes due to glaucoma. In order to study the effects of topical antiglaucoma medications on aqueous humor protein composition, we analyzed the aqueous humor of rabbit eyes topically treated with various antiglaucoma medications (timolol, pilocarpine, and dipivefrin). One eye of each rabbit was treated with the experimental drug, and the fellow eye was treated with saline solution (control). Thirty-six aqueous humor samples from 18 rabbits were obtained after 24 hours and 36 samples were obtained from 18 additional rabbits after 7 days of topical drug treatment. The protein composition of the aqueous humor samples was analyzed by sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Significant protein differences in aqueous humor samples were found between the eyes treated with timolol and the control eyes, whereas no significant differences were found between the eyes treated with pilocarpine or dipivefrin and the controls. These protein differences ranged from 14,000 to 18,000 daltons in molecular weight.

[Intracardiac operations performed in beating heart through mini-thoracotomy in 34 patients]

OBJECTIVE

To introduce the technique of intracardiac operations performed in beating heart through mini-thoracotomy.

METHOD

>From March 1995 to June 1997, intracardiac operations were performed in beating heart through right subaxillary anterolateral mini-thoracotomy with normothermic extracorporeal circulation in 34 patients. 16 patients had atrial septal defect, 14 ventricular septal defect, 2 mitral insufficiency, 1 right coronary artery-right ventricular fistula, and 1 Ebstein's anomaly.

RESULT

The mean cardiopulmonary bypass time was 22.54 minutes. There were no embolism, arrhythmia and cerebral complications. Postoperative hospital stay was 8.0 +/- 2.2 days. All the patients had no heart murmur and residual shunt, and enjoyed a full range of physical activities in a follow-up of 2 to 26 months.

CONCLUSION

Intracardiac operations performed in beating heart through right subaxillary anterolateral mini-thoracotomy appears to be less invasive, simple, safe and cosmetic.

Basic science and clinical aspects of wound healing in glaucoma filtering surgery

Success of glaucoma filtration surgery is influenced by the wound healing response. Attention has been focused on pharmacological agents to control a process that leads to excessive scarring and eventual failure of glaucoma filtration surgery. Several agents, including 5-fluorouracil and mitomycin C, as well as other antiproliferative drugs will be discussed. Newer antifibrotic agents and novel drug delivery systems are under development in tissue culture and animal models in an effort to improve efficacy and safety. This article summarizes current treatment modalities and future prospects to prevent excessive wound healing and improve the success of glaucoma filtration surgery.

Reproducibility of intraocular pressure and outflow facility measured by pneumatic tonography and Schiotz tonography

The purpose of this study was to compare means, variability, and reproducibility in intraocular pressure and in outflow facility measured repeatedly over several days by Bio-Rad pneumatonography and Schiotz tonography in normal human volunteers. For each instrument a measurement of intraocular pressure and one of outflow facility were obtained at each of three repeated examinations of eight healthy subjects in the supine position. For pressure, the Bio-Rad mean was significantly higher by 5.31 mmHg than the Schiotz mean (p < 0.00005). Reproducibility was 71.1% and 59.0% for the Bio-Rad and Schiotz, respectively. For outflow, the Bio-Rad and Schiotz means were not significantly different. Reproducibility was 17.3% and 58.7% for the Bio-Rad and Schiotz, respectively. For measuring pressure, both the Bio-Rad and Schiotz instruments had good reproducibility; for measuring outflow, the Bio-Rad and Schiotz instruments had low and good reproducibility, respectively.

Measurement of Plasmodium falciparum growth rates in vivo: a test of malaria vaccines

Several prototype vaccines against the asexual blood stage of malaria are undergoing preclinical and phase I testing. Although these vaccines have been chosen for their ability to elicit an anti-parasite response, no practical and sensitive clinical trial procedure has been available for measuring their impact on parasite growth. We describe a system that allows parasite growth rates to be measured in volunteers through the incubation period. Two necessary elements of this system are developed: suitable blood-stage Plasmodium falciparum inocula, and a highly sensitive and quantitative assay to measure parasite growth during the incubation period. We infected five nonimmune volunteers with an inoculum as small as 300 parasites and demonstrated that the resultant in vivo asexual parasite growth rates were reproducible at 12-15-fold per cycle. The system allowed the infection to be followed for eight days before treatment without symptoms developing. These findings suggest that it is feasible to directly measure the anti-parasite efficacy of a prototype malaria vaccine in human volunteers without subjecting them to the risk of disease.

Influence of n-3 fatty acid supplementation on the endogenous activities of plasma lipases

The aim of these studies was to explore the possibility that enhanced triacylglycerol clearance may contribute to the hypotriacylglycerolemic effect of n-3 fatty acids in humans. Healthy subjects (n = 20) and hypertriacylglycerolemic patients (n = 6) were given a placebo (olive oil, OO) or a fish-oil concentrate (FOC; 41% eicosapentaenoic acid and 23% docosahexaenoic acid) in two, independent, randomized, blind trials. For the healthy subjects, the FOC treatment period was 3 wk long and FOC intakes were 5 g/d. For the patients, treatment periods were 4 wk long and dosages were 5 g.70 kg body wt-1.d-1. Washout periods were 2-4 wk for both groups. Blood samples were drawn at the end of each phase and analyzed for plasma lipids, lipoproteins, and endogenous (nonheparin-stimulated) activities of lipoprotein lipase (LPL) and hepatic lipase (HL). In the healthy subjects the FOC decreased plasma triacylglycerol concentrations by 18% (P < 0.01), whereas in the patients concentrations were reduced by 35% (P < 0.05). Low-density-lipoprotein-cholesterol concentrations increased by 25% in the latter group (P = 0.06). FOC increased the endogenous activities of LPL and HL by 62% and 68%, respectively (P < 0.0001), in the healthy subjects, but only LPL in the patients (65%, P < 0.005). These data suggest that endogenous lipase activities may be altered by nutritional interventions, and further, that accelerated lipolysis could contribute, at least in part, to the observed effects of n-3 fatty acids on human lipoprotein metabolism.

Assessment of the humoral immune response against Plasmodium falciparum rhoptry-associated proteins 1 and 2

Naturally occurring antibody responses to Plasmodium falciparum rhoptry-associated proteins 1 and 2 (RAP-1 and RAP-2) were measured with recombinant and parasite-derived forms of the antigens. For comparative purposes, responses to multiple forms of three other malarial antigens were also examined. The sera of 100 Papua New Guineans were screened for antibodies. Eighty-six and 82% of individuals over 30 years of age had antibodies that recognized parasite-derived RAP-1 and RAP-2, respectively. Importantly, we found that recombinant and native antigens share linear epitopes seen by the human immune system; thus, the recombinant proteins may be adequate human immunogens. However, antibodies affinity purified on recombinant RAP-1 reacted with other antigens in addition to parasite-derived RAP-1. Thus, the antigenicity of RAP-1 may have been overestimated previously. The recognition of RAP-1 and RAP-2 correlated with age and with the recognition of recombinant forms of the ring-infected erythrocyte surface antigen, merozoite surface protein 1, and merozoite surface antigen 2 (MSA2) antigens. Antibodies to these antigens appear to be generated in response to the total exposure to malaria of the host. Antibodies to conserved regions of MSA2 had stronger correlations with both age and the recognition of other antigens than did the full-length recombinant MSA2 molecule. In contrast to results with the other antigens, there was no significant difference in the ages of individuals with a certain antibody titer to the full-length recombinant or parasite-derived MSA2 molecule, but antibodies to these two antigens did correlate with parasitemia. For all antigens tested, antibody levels after two infections can approach the peak levels of antibodies obtained in immune individuals.

Epidemiological features of Guillain-Barré syndrome in Sweden, 1978-93

OBJECTIVES

To describe the incidence of Guillain-Barré syndrome in Sweden during the period 1978-93 and its temporal and geographical variations.

METHODS

Stratified and Poisson regression analyses and tests for detection of small epidemics were applied to population based hospital discharge data from 2257 incident cases of Guillain-Barré syndrome in Sweden during the study period.

RESULTS

The incidence of Guillain-Barré syndrome was (1) 1.77 per 100000 person-years when age adjusted to the European population; (2) higher in males; and (3) stable across time, although occasional increases of annual incidence rates were found-namely, in 1978 (relative risk (RR) 1.30 (95% CI 1.10-1.54)), and in 1983 (RR 1.24 (95% CI 1.06-1.40)). The incidence increased with age and was bimodal, with peaks at 20-24 and 70-74 years. There was a moderate but significant seasonality with a peak in August, particularly among the young age groups. The age adjusted incidence by county varied from 1.11 to 2.57 per 100000 person-years. Neither temporal nor spatial clustering was significant, except during the period July-September in 1983 at ages below 40 years.

CONCLUSIONS

The incidence of Guillain-Barré syndrome in Sweden during the period 1978-93 had a magnitude similar to those described in other surveys, a bimodal distribution by age, and modest geographical and temporal variations with significantly high rates in 1978 and 1983 and in autumn. Minor outbreaks might have passed unnoticed up to the present. Whereas reported drug induced cases of Guillain-Barré syndrome may in part explain the high incidence in 1983, the cause of the aberrant incidence in 1978 remains unknown. Epidemiological surveillance of Guillain-Barré syndrome in Sweden might have been useful.

[Cardiac operation via subaxillary and anterolateral subaxillary thoracotomy with cardiopulmonary bypass]

From March 1995 to August 1996, 50 patients underwent cardiac operation through subaxillary and anterolateral subaxillary thoracotomy with cardiopulmonary bypass. 17 had atrial septal defect, 26 ventricular septal defect, 3 mitral stenosis and insufficiency, 1 isolated mitral insufficiency, 1 double chamber of right ventricle, 1 partial common atrioventricular canal, and 1 cor atriatriatum. All operations were successfully performed without technical difficulty. The cardiopulmonary bypass time was 40.19 +/- 17.17 minutes with aortic cross-clamping time of 22.59 +/- 11.06 minutes. There were no operative death and complications. In conclusion, the subaxillary and anterolateral subaxillary thoracotomy incision appears to be a minimally invasive, safe, effective and cosmetic alterative to median sternotomy for cardiac operation.

The com locus controls genetic transformation in Streptococcus pneumoniae

Genetic exchange by natural transformation in Streptococcus pneumoniae occurs in a cell-density dependent process and is initiated by a small extracellular signalling molecule, the competence-stimulating peptide (CSP). comC, the gene for this peptide, has previously been identified and encodes a 44 amino acid pre-peptide that is apparently processed to an active molecule that consists of the C-terminal 17 amino acids. We have sequenced the region adjacent to comC and shown that it is the first gene of an operon, com, consisting of two downstream elements, comD and comE, which encode members of the two-component family of sensor regulators. Null mutants with defects in either comC or comD were transformation deficient and failed to respond to exogenous CSP. A comC mutant did not exhibit any detectable CSP activity, while a comD mutant that contained an intact comC produced minimal CSP activity. In mixed-culture experiments consisting of isogenic pairs of pneumococci (Csp+ and Csp-), we showed that induction of competence by quorum sensing was independent of CSP. Northern analysis showed that com was transcribed as a single polycistronic message, while analysis of strains with transcriptional fusions showed that com was constitutively expressed under conditions that both promoted or repressed the development of competence. Finally, we showed genetically and biochemically a CSP-dependent transcription of rec, a competence-induced locus, and that ComD and ComE are required for this CSP-dependent expression.

Guillain-Barré syndrome in Stockholm County, 1973-1991

In order to describe the incidence of Guillain-Barré syndrome (GBS) in Stockholm County (SC) and hospital use by GBS patients, we conducted a retrospective epidemiological study on GBS covering 1973-1991, using the Hospital Inpatient Register in SC. There were 556 patients, bona fide residents in the county during the study period, discharged from hospitals with GBS diagnosis. The mean annual incidence, age-adjusted to the European population, was 1.84 (2.15 for males and 1.57 for females) per 100,000 population. The incidence increased with age and showed a bimodal distribution with peaks in the 10-29 and 70-79 age-groups. Annual incidence rates were highest in 1978 and 1983. Neither heterogeneity of annual or monthly rates nor linear trends during the period were found to be significant, except in 1978 for patients below 40 years of age, RR 1.72 (95% CI 1.08-2.71) and in 1983 for patients at ages 40 years and over, RR 1.48 (95% CI 1.02-2.16), when compared with GBS incidences in the same age-groups during the remaining study period. The mean +/- SD duration of hospital stay, including long-term care or rehabilitation institutions, for GBS patients, was 86 +/- 210 days, with considerably longer duration for the elderly. The rate of hospital use by GBS patients was 162 days per 100,000 inhabitants per year. In accordance with results of prior studies in South-West Stockholm and described GBS epidemics in Sweden, this study supports that an etiologically different subgroup of GBS exists at ages below 40 years, and that relevant but small time-space variations, such as the reported zimeldine epidemic in 1983, resist detection by hospital data analysis of pooled GBS cases. Efficient epidemiological surveillance of GBS may require targeted development of clinico-epidemiological tools.

Stimulation of phosphorylase phosphatase activity of protein phosphatase 2A1 by protamine is ionic strength dependent and involves interaction of protamine with both substrate and enzyme

The effects of protamine on the phosphorylase phosphatase activity of porcine cardiac protein phosphatase 2A1 (PP2A1) were complex and ionic strength dependent. Under ionic strength conditions that protamine activation was optimal, activation of PP2A1 by either dilution or heparin was prevented. A time-dependent deactivation of the protamine-stimulated phosphatase activity was observed when PP2A1 was preincubated with protamine. Protamine forms a very tight association with phosphorylase a, which is optimal at a 1:1 protamine:phosphorylase a monomer molar ratio. Protamine activation of PP2A1 activity, however, is not substrate-directed since the basic polypeptide did not stimulate either the activity of the catalytic subunit or trypsinolysis of [32P]phosphorylase a. The interaction of protamine with phosphorylase a does not apparently involve the phosphorylation site in the protein substrate (ser 14). The activation of PP2A1 by protamine is proposed to involve part of the basic polypeptide, not associated with phosphorylase a monomer, interacting with the regulatory and/or the catalytic subunit(s) of the phosphatase. A minimal model for the activation of PP2A1 by protamine was tested kinetically. In this model, free PP2A1 binds with decreasing affinities to the protamine:phosphorylase a complex, free phosphorylase a, and free protamine. Protamine decreases the K(m) of PP2A1 for the phosphorylase a monomer 5-fold and increases the Vmax 17-fold. Interaction of free protamine with PP2A1 inhibits the phosphatase activity.

[The modulation of renal tubular epithelial cells treated with hypoxia on renal interstitial fibroblasts in coculture]

To clarify cell-cell interaction in the pathogenesis of renal tubulointerstitial nephritis (TIN), the effect of renal tubular epithelial cells (TEC) on renal interstitial peritubular fibroblasts (PTF) was examined in cell coculture system without direct contact. TEC and PTF were prepared from the kidney of BALB/C mice. Firstly, TEC were plated into intercup chambers of 24-well plates and incubated at 37 degrees C in a humidified 5% CO2 atmosphere for 72 hours. Then the cells were cultured in an incubator which was full of 95% N2 for 24 hours. Secondly, those intercups with hypoxia-treated TEC were floated on the wells of 24-well plates containing PTF which had been incubated for 24 hours. The TEC and the PTF were cocultured for another 48 hours. PTF were also cocultured with normal TEC as controls. The parameters of the cocultured PTF were measured as follows. (1) Cell proliferation examined by MTT incorporation method and the cell numbers were detected with total acid phosphatase activity. (2) Fibronectin (FN), laminin (LN) and collagen IV in the supernatants of coculture system were measured by ELISA method. (3) The distribution of ICAM-1 on the cell membrane of PTF was determined by laser confocal scanning microscopy.

RESULTS

(1) The number of PTF cocultured with hypoxiatreated TEC was greater than that of controls (P < 0.01). (2) The level of FN and LN in the supernatants of the PTF cocultured with hypoxia-treated TEC was higher than that of the controls (P < 0.05). (3) The expression of ICAM-1 on PTF cocultured with hypoxia-treated TEC was higher than that of controls (P < 0.01). In conclusion the interaction of PTF and TEC may play a role in the pathogenesis of TIN.

Skeletal muscle of a growing organism has a greater transformation after electrical stimulation than adult skeletal muscle

Six adult sheep and four newborn lambs (5 days old) were implanted with stimulator leads into the latissimus dorsi muscle and connected to a Myostim 7220 pacing system (Telectronics Pacing Systems, Inc., Englewood, CO). Electrical stimulation was started immediately after the operation. After 8 weeks of electrical stimulation, contractile force (CF) in adult sheep decreased to 76-81%, and to 78-82% in lambs. After 2 weeks' delay, CF in adults was 96-98%, and only 89-93% in lambs. After a 30 min intensive stress test, unconditioned control muscle lost 39% in lambs and 43% in adults. Muscle conditioned for 8 weeks lost 7-8% CF. However, after 2 weeks' delay, CF in adult muscle lost 33%, but only 12% in lambs. After cessation of electrical stimulation, the LDH-5 and LDH-1 + 2 fractions reverted to initial levels in adults, whereas in lambs, these levels continued to follow trends established during electrical stimulation. In both adults and lambs, the percent area occupied by the mitochondria increased during electrical stimulation by 6.9% in adults and 6.5% in lambs. After electrical stimulation cessation, the percent area in adults returned to baseline levels, whereas it continued to be elevated in lambs (3.3% vs 5.1%, respectively). The transformed muscle of the lamb did not revert to baseline levels after a delay period.

A 'litmus test' for molecular recognition using artificial membranes

BACKGROUND

Sensitive and selective molecular recognition is important throughout biology. Certain organisms and toxins use specific binding at the cell surface as a first step towards invasion. A new series of biomolecular materials, with novel optical and interfacial properties, have been designed to sense molecular recognition events. These polymers, the diacetylenic lipids, have previously been shown to undergo chromatic transitions in response to virus binding to the surface of the material.

RESULTS

Gangliosides that specifically bind cholera toxin, heat-labile Escherichia coli enterotoxin and botulinum neurotoxin were incorporated into a matrix of diacetylenic lipids, 5-10% of which were derivatized with sialic acid. The lipids were self-assembled into Langmuir-Blodgett layers and polymerized with ultraviolet irradiation, yielding a polydiacetylene membrane with a characteristic blue color into which the ganglioside is non-covalently incorporated. When toxin is added, the polymerized membrane turns red. The response is specific and selective, and can be quantified by visible absorption spectrophotometry.

CONCLUSIONS

Polydiacetylenic lipid membranes offer a general 'litmus test' for molecular recognition at the surface of a membrane. A concentration of 20 ppm of protein could be detected using polymerized thin films. The speed, sensitivity and simplicity of the design offers a new and general approach towards the direct colorimetric detection of a variety of different molecules.

Experimental human Plasmodium falciparum infections: longitudinal analysis of lymphocyte responses with particular reference to gamma delta T cells

The kinetics of the gamma delta T-cell response was analysed in the context of the overall haematological response in subjects experimentally infected with sporozoites of Plasmodium falciparum. Numbers of gamma delta and alpha beta T cells and NK cells declined markedly during infection to reach minimum values 12-13 days post-infection when the patients were ill. This decline commenced from the beginning of the erythrocytic cycle and well before parasites could be detected microscopically and clinical symptoms developed. Platelet numbers also declined. In vivo activation of gamma delta T cells was evident with sequential up-regulation of the activation markers CD69 and HLA-DR. gamma delta T cell numbers were highest after treatment with the majority being CD4-CD8-, HLA-DR+ and showing reduced CD45RA expression. Contrary to some published observations gamma delta T-cell percentages remained within the normal range. Little evidence of upregulation of activation or memory markers was observed in the alpha beta T-cell population. In vitro proliferative responses to malaria antigen which involve gamma delta T cells were lost as the infection progressed and the lymphocyte count declined but these could be restored with the addition of exogenous IL-2 to cultures. The authors findings are consistent with a protective and/or immunomodulatory role for gamma delta T cells in malaria.

The effects of growth factors on Tenon's capsule fibroblasts in serum-free culture

This study was performed to develop and improve a completely defined in vitro ocular wound-healing model of fibroblast proliferation for glaucoma filtration surgery. This model is essential for the investigation of protein-sensitive drugs and cytokines. Tenon's capsule fibroblasts in their third passage were incubated overnight, washed free of serum, and fed defined media, Aim V or Clonetics FBM serum-free medium containing platelet-derived growth factor, basic fibroblast growth factor, epidermal growth factor, or fibronectin at various dilutions and in combinations at optimum concentrations. Proliferation was measured by 3H-thymidine incorporation at 1, 3, and 7 days. Morphology was compared to controls fed Minimum Essential Medium + 10% serum. Single factors stimulated the greatest amount of thymidine uptake on day 3. Optimum concentrations were epidermal growth factor at 5 ng/ml, basic fibroblast growth factor at 10 ng/ml and platelet-derived growth factor at 20 ng/ml. Identical combinations of factors stimulated nearly twice the thymidine uptake in Clonetics medium as in Aim V. Epidermal growth factor activity was inhibited by either basic fibroblast growth factor or platelet-derived growth factor. Basic fibroblast growth factor and platelet-derived growth factor together produced a less than additive effect. The performance of either serum-free medium may be improved by the addition of basic fibroblast growth factor or platelet-derived growth factor. The optimum serum-free medium (Clonetics FBM) with growth factors was unable to stimulate proliferation as much as Minimum Essential Medium + 10% NBS, but was successful in maintaining viability during the 7 day test period.

Characterization of tumor-specific cytotoxic effector cells with a novel CD3-/Thy-1+ phenotype

The introduction and expression of allogeneic MHC class I genes in tumors can generate tumor-specific immunity which subsequently results in the regression of parental tumors. Immunization of naive (AKR/J x C57BL/6)F1 mice with H-2Kb-transformed K36 tumor cells was found to render recipient mice immune to a subsequent challenge by parental K36 tumor cells. Two types of cytotoxic T effector cells were demonstrated in these immune mice. One of the cytotoxic effector cells generated against the K36 tumor cells is the conventional CD3+ cells, and these account for approximately one-third of the total observed tumor-specific cytotoxicity in vitro. The other cytotoxic effector cell generated following the immunization of (AKR/J x C57BL/6)F1 mice with the H-2Kb-transformed K36 cells had the CD3-/Thy-1+ phenotype, and accounted for the remaining two-thirds of the observed tumor-specific cytotoxicity in vitro. These CD3-/Thy-1+ cells can lyse parental K36 tumor cells in a tumor-specific fashion, and tumor-specific immunity can be adoptively transferred to naive animals via the CD3-/Thy-1+ cells. In contrast to CD3+ CTL, CD3-/Thy-1+ cells express CD45RBlow, Ly-6Chigh, and HSA molecules. Although the CD3-/Thy-1+ cells can be activated in vitro by IL-2, TPA, and ionomycin, they cannot be propagated in vitro. The CD3-/Thy-1+ cells undergo apoptosis following prolonged culture in vitro. At present, the exact mechanism(s) by which CD3-/Thy-1+ cells can mediate tumor-specific cell lysis in the absence of identifiable T cell receptor molecules is unknown; nevertheless, these data suggest the existence of a novel T cell type to combat tumors.

Comparative efficacy of antiviral drugs on human ocular fibroblasts

The effects of several antiviral drugs on fibroblast attachment and proliferation from human Tenon's capsule were investigated. These drugs included purine nucleoside analogs, vidarabine and acyclovir (ACV); pyrimidine nucleoside analog, AZT; and a synthetic cyclic primary amine, amantadine. Fibroblast attachment and proliferation inhibition were determined by Coulter counter, a colorimetric assay of the enzyme hexosaminidase, and a 3H-thymidine uptake assay. Amantadine and AZT inhibited fibroblast attachment at concentrations higher than 6.61 x 10(-4)M and 3.73 x 10(-4) M, respectively. Amantadine and AZT had inhibitory effects on fibroblast proliferation as early as day 1, whereas vidarabine and ACV manifested their inhibitory effects after day three by Coulter counter and hexosaminidase assays. For amantadine, AZT, ACV and vidarabine, the 50% inhibitory dose (ID50) were 4.94 x 10(-5) M, 1.26 x 10(-5) M, 4.60 x 10(-4) M, and 1.52 x 10(-5) M at day 9, respectively, as measured by 3H-thymidine uptake assay. All four antiviral agents tested had inhibitory effects on human ocular fibroblast proliferation and their inhibitory potential decreased in the order of amantadine > or = vidarabine > AZT > or = ACV.

A continuous spectrophotometric assay for phosphorylase kinase

A continuous spectrophotometric assay for the determination of the initial rate of the phosphorylase kinase catalyzed reaction at pH 7.0 is presented. The assay incorporates two coupling enzyme systems: (a) recombinant rabbit skeletal muscle type 1 protein phosphatase catalytic subunit which dephosphorylates the phosphorylase a product of the phosphorylase kinase reaction, and (b) the system of Webb (Proc. Natl. Acad. Sci. USA 89, 4884-4887, 1992), which uses purine nucleoside phosphorylase and its chromophoric substrate, 7-methyl-6-thioguanosine, for the quantitation of the resultant inorganic phosphate. The effects of reaction components on the enzyme activities were studied. The system was standardized and validated. The continuous coupled enzyme system was used for the kinetic analysis of nonactivated phosphorylase kinase at pH 7.0. Km and kcat values of 15.36 +/- 0.2 microM (phosphorylase b monomer) and 21 +/- 1.12 s-1, respectively, were determined.

Identification and characterization of a Bacteroides gene, csuF, which encodes an outer membrane protein that is essential for growth on chondroitin sulfate

Bacteroides thetaiotaomicron can utilize a variety of polysaccharides, including charged mucopolysaccharides such as chondroitin sulfate (CS) and hyaluronic acid (HA). Since the enzymes (chondroitin lyases I and II) that catalyze the first step in breakdown of CS and HA are located in the periplasm, we had proposed that the first step in utilization of these polysaccharides was binding to one or more outer membrane proteins followed by translocation into the periplasm, but no such outer membrane proteins had been shown to play a role in CS or HA utilization. Previously we have isolated a transposon-generated mutant, CS4, which was unable to grow on CS or HA but retained the ability to grow on disaccharide components of CS. This phenotype suggested that the mutation in CS4 either blocked the transport of the mucopolysaccharides into the periplasmic space or blocked the depolymerization of the mucopolysaccharides into disaccharides. We have mapped the CS4 mutation to a single gene, csuF, which is capable of encoding a protein of 1,065 amino acids and contains a consensus signal sequence. Although CsuF had a predicted molecular weight and pI similar to those of chondroitin lyases, it did not show significant sequence similarity to the Bacteroides chondroitin lyase II, a Proteus chondroitin ABC lyase, or two hyaluronidases from Clostridium perfringens and Streptococcus pyogenes, nor was any CS-degrading enzyme activity associated with csuF expression in Bacteroides species or Escherichia coli. The deduced amino acid sequence of CsuF exhibited features suggestive of an outer membrane protein. We obtained antibodies to CsuF and demonstrated that the protein is located in the outer membrane. This is the first evidence that a nonenzymatic outer membrane protein is essential for utilization of CS and HA.

Force enhancement of skeletal muscle used for dynamic cardiomyoplasty and as a skeletal muscle ventricle

Some patients with pre end-stage congestive heart disease do not receive a significant hemodynamic benefit from dynamic cardiomyoplasty because, during prolonged preoperative immobilization, their latissimus dorsi muscle (LDM) becomes extremely weak. It is the authors' hypothesis that the local administration of an anabolic steroid into an electrically stimulated LDM will produce a thicker and stronger muscle with significant resistance to fatigue. The electrical stimulation training protocol of sheep continued for 8 weeks. For localized anabolic steroid administration an osmotic pump was placed in a subcutaneous pocket and the catheter was introduced into the LDM. The contractile force of electrically stimulated and unstimulated control muscle was studied. Control data were calculated as 100% and all other data were corrected to control. After 4 weeks there was no decrease in contractile force. The change seen was from 88 to 100% with different preloads (10, 15, and 20 g/kg) and amplitudes of impulses (5 and 10 V). After 8 weeks, the LDM was more powerful than before electrical stimulation, with a change of 97-133%. Usually after 8 weeks of electrical stimulation alone, contractile force decreases to 70-75%. During a fatigue test (30 min, 100 bursts per minute, 10-25 Hz, ripple frequency, 10 V impulse amplitude) after 4 and 8 weeks of our protocol, the LDM lost only 12% of its initial force, whereas control muscle lost 40%. Thus local anabolic steroid administration makes the LDM stronger and more useful for cardiomyoplasty.

A continuous spectrophotometric assay for protein phosphatases

A continuous spectrophotometric assay for the determination of protein phosphatase activity is presented. The assay incorporates the coupled enzyme system of Webb (M. R. Webb, 1992, Proc. Natl. Acad. Sci. USA 89, 4884-4887), which used purine nucleoside phosphorylase and the chromophoric substrate 7-methyl-6-thioguanosine for the quantitation of inorganic phosphate. The assay is exemplified and validated here for the phosphorylase phosphatase activity of protamine-stimulated protein phosphatase 2A1 (PP-2A1). The effects of reaction components on the activities of both PP-2A1 and purine nucleoside phosphorylase were studied. The application of the coupled assay system to kinetic analysis of the phosphorylase phosphatase activity of PP-2A1 and to the assay of the catalytic subunits of type 1 and 2A protein phosphatases and a recombinant type 1 catalytic subunit is demonstrated. The applicability of this coupled enzyme system to the assay of other protein phosphatases is discussed.

Use of suppressor analysis to find genes involved in the colonization deficiency of a Bacteroides thetaiotaomicron mutant unable to grow on the host-derived mucopolysaccharides chondroitin sulfate and heparin

Bacteroides thetaiotaomicron, one of the numerically predominant species of human colonic bacteria, can ferment two types of host-derived mucopolysaccharides, chondroitin sulfate (CS) and heparin (HP). Originally, the pathways for utilization of CS and HP appeared to be completely independent of each other, but we have recently identified a gene, chuR, that links the two utilization systems. chuR is probably a regulatory gene, but it controls only a small subset of genes involved in CS and HP utilization. Some of the genes controlled by chuR are important for survival of B. thetaiotaomicron in the colon because a mutant that no longer produced ChuR was unable to compete with the wild type for colonization of the intestinal tract of germfree mice. In an attempt to identify genes that either were controlled by ChuR or encoded proteins that interacted with ChuR, we used transposon mutagenesis to generate suppressor mutations that restored the ability of a chuR disruption mutant to grow on CS and HP. Two classes of suppressors were isolated. One class grew as well as the wild type on CS and HP and had recovered the ability to compete with the wild type for colonization of the germfree mouse intestinal tract. A second class grew more slowly on CS and HP and reached only a half-maximum level on CS. This mutant still had a colonization defect. Representatives of both classes of suppressor mutants have been characterized, and the results of this analysis suggest that the transposon insertions in the suppressor mutants probably affected regulatory genes whose products interact with ChuR.