IV. Growth Failure in Institutionalized Children

Children within institutional care settings experience significant global growth suppression, which is more profound in children with a higher baseline risk of growth impairment (e.g., low birth weight [LBW] infants and children exposed to alcohol in utero). Nutritional insufficiencies as well as suppression of the growth hormone-insulin-like growth factor axis (GH-IGF-1) caused by social deprivation likely both contribute to the etiology of psychosocial growth failure within these settings. Their relative importance and the consequent clinical presentations probably relate to the age of the child. While catch-up growth in height and weight are rapid when children are placed in a more nurturing environment, many factors, particularly early progression through puberty, compromise final height. Potential for growth recovery is greatest in younger children and within more nurturing environments where catch-up in height and weight is positively correlated with caregiver sensitivity and positive regard. Growth recovery has wider implications for child well-being than size alone, because catch-up in height is a positive predictor of cognitive recovery as well. Even with growth recovery, persistent abnormalities of the hypothalamic-pituitary-adrenal system or the exacerbation of micronutrient deficiencies associated with robust catch-up growth during critical periods of development could potentially influence or be responsible for the cognitive, behavioral, and emotional sequelae of early childhood deprivation. Findings in growth-restricted infants and those children with psychosocial growth are similar, suggesting that children experiencing growth restriction within institutional settings may also share the risk of developing the metabolic syndrome in adulthood (obesity, Type 2 diabetes mellitus, hypertension, heart disease). Psychosocial deprivation within any care-giving environment during early life must be viewed with as much concern as any severely debilitating childhood disease.

IV. Growth Failure in Institutionalized Children

Children within institutional care settings experience significant global growth suppression, which is more profound in children with a higher baseline risk of growth impairment (e.g., low birth weight [LBW] infants and children exposed to alcohol in utero). Nutritional insufficiencies as well as suppression of the growth hormone-insulin-like growth factor axis (GH-IGF-1) caused by social deprivation likely both contribute to the etiology of psychosocial growth failure within these settings. Their relative importance and the consequent clinical presentations probably relate to the age of the child. While catch-up growth in height and weight are rapid when children are placed in a more nurturing environment, many factors, particularly early progression through puberty, compromise final height. Potential for growth recovery is greatest in younger children and within more nurturing environments where catch-up in height and weight is positively correlated with caregiver sensitivity and positive regard. Growth recovery has wider implications for child well-being than size alone, because catch-up in height is a positive predictor of cognitive recovery as well. Even with growth recovery, persistent abnormalities of the hypothalamic-pituitary-adrenal system or the exacerbation of micronutrient deficiencies associated with robust catch-up growth during critical periods of development could potentially influence or be responsible for the cognitive, behavioral, and emotional sequelae of early childhood deprivation. Findings in growth-restricted infants and those children with psychosocial growth are similar, suggesting that children experiencing growth restriction within institutional settings may also share the risk of developing the metabolic syndrome in adulthood (obesity, Type 2 diabetes mellitus, hypertension, heart disease). Psychosocial deprivation within any care-giving environment during early life must be viewed with as much concern as any severely debilitating childhood disease.

A robust MRI-compatible system to facilitate highly accurate stereotactic administration of therapeutic agents to targets within the brain of a large animal model

Achieving accurate intracranial electrode or catheter placement is critical in clinical practice in order to maximise the efficacy of deep brain stimulation and drug delivery respectively as well as to minimise side-effects. We have developed a highly accurate and robust method for MRI-guided, stereotactic delivery of catheters and electrodes to deep target structures in the brain of pigs. This study outlines the development of this equipment and animal model. Specifically this system enables reliable head immobilisation, acquisition of high-resolution MR images, precise co-registration of MRI and stereotactic spaces and overall rigidity to facilitate accurate burr hole-generation and catheter implantation.

To demonstrate the utility of this system, in this study a total of twelve catheters were implanted into the putamen of six Large White Landrace pigs. All implants were accurately placed into the putamen. Target accuracy had a mean Euclidean distance of 0.623 mm (standard deviation of 0.33 mm). This method has allowed us to accurately insert fine cannulae, suitable for the administration of therapeutic agents by convection-enhanced delivery (CED), into the brain of pigs. This study provides summary evidence of a robust system for catheter implantation into the brain of a large animal model. We are currently using this stereotactic system, implantation procedure and animal model to develop catheter-based drug delivery systems that will be translated into human clinical trials, as well as to model the distribution of therapeutic agents administered by CED over large volumes of brain.

Growth and associations between auxology, caregiving environment, and cognition in socially deprived Romanian children randomized to foster vs ongoing institutional care

OBJECTIVES

To determine effects of improved nurturing compared with institutional care on physical growth and to investigate the association between growth and cognitive development.

DESIGN

A randomized controlled trial beginning in infants (mean age, 21.0 months; range, 5-32 months), with follow-up at 30, 42, and 54 months of age.

SETTING

Institutionalized and community children in Bucharest, Romania.

PARTICIPANTS

One hundred thirty-six healthy institutionalized children from 6 orphanages and 72 typically developing, never-institutionalized children.

INTERVENTION

Institutionalized children were randomly assigned to receive foster care or institutional care as usual.

OUTCOME MEASURES

Auxology and measures of intelligence over time.

RESULTS

Growth in institutionalized children was compromised, particularly in infants weighing less than 2500 g at birth. Mean height and weight, though not head size, increased to near normal within 12 months in foster care. Significant independent predictors for greater catch-up in height and weight included age younger than 12 months at randomization, lower baseline z scores, and higher caregiving quality, particularly caregiver sensitivity and positive regard. Baseline developmental quotient, birth weight, and height catch-up were significant independent predictors of cognitive abilities at follow-up. Each incremental increase of 1 in standardized height scores between baseline and 42 months was associated with a mean increase of 12.6 points (SD, 4.7 points) in verbal IQ (P < .05).

CONCLUSIONS

Foster care had a significant effect on growth, particularly with early placement and high-quality care. Growth and IQ in low-birth-weight children are particularly vulnerable to social deprivation. Catch-up growth in height under more nurturing conditions is a useful indicator of caregiving quality and cognitive improvement.

Auxological evaluation and determinants of growth failure at the time of adoption in Eastern European adoptees

AIM

To identify factors contributing to growth failure in international adoptees (IAs) from Eastern Europe.

STUDY DESIGN

138 IAs from Eastern Europe, 6-59 months old, were evaluated within 3 weeks of US arrival. Complete history, anthropometry, and serum for growth factors were obtained. Facial features were examined for risk of prenatal alcohol exposure.

RESULTS

Upon arrival, mean height (-1.23 +/- 1.07), weight (-1.43 +/- 1.29), and occipitofrontal circumference (OFC) (-0.63 +/- 1.10) SDS in IAs were significantly less than population means for US children. In a multiple regression model, age, low birth weight (LBW), insulin-like growth factor binding protein-3, and high risk for fetal alcohol syndrome were independent predictors of height SDS. LBW also independently predicted lower weight SDS and smaller OFC SDS.

CONCLUSIONS

We recommend that IAs undergo screening upon US arrival to identify risk factors for poor growth, particularly evidence of LBW and fetal alcohol exposure. Catch-up growth should be monitored in all children following adoption.

A spatially resolved ion temperature diagnostic for the National Ignition Facility

The concepts and initial development efforts for a spatially resolved ion temperature diagnostic are described. The diagnostic is intended for Inertial Confinement Fusion experiments at the National Ignition Facility and is an integration of neutron aperture imaging and ion temperature techniques. The neutron imaging technique is extended by recording tomographic projections of the radiation-to-light converter on a streak camera. The streak record is used to calculate images at multiple times during the arrival of the thermally broadened 14.1 MeV neutron flux. The resulting set of images is used to determine the spatially resolved ion temperature.

Iron deficiency in international adoptees from Eastern Europe

OBJECTIVE

To assess iron deficiency (ID) in international adoptees after adoption.

STUDY DESIGN

Participants (n = 37) were adopted into the United States from Eastern Europe before they were 24 months of age. Baseline (within 1 month post-adoption) and follow-up (6 months post-adoption) assessments included routine post-adoption clinical evaluations, anthropometrics, dietary intakes, and iron measures (hemogram and serum analysis).

RESULTS

At adoption and follow-up, mean percent transferrin saturation and mean corpucuscular volume were low compared with the US population. Mean serum ferritin concentration became lower than the US population at follow-up, although the mean daily iron intake was more than the Recommended Dietary Allowance. Participants with Giardia lamblia at baseline had more compromised iron status at baseline and follow-up. Growth rate (change in z-score/months between assessments) was negatively correlated with change in serum ferritin concentrations between baseline and follow-up (r = -0.34; P < .05).

CONCLUSIONS

International adoptees had compromised iron status, with ID more prevalent in participants with G lamblia, a parasite that may interfere with iron absorption. The persistent ID at follow-up was likely caused by the erythropoietic demands of catch-up growth.

Plant folk medicines for gastrointestinal disorders among the main tribes of Sonora, Mexico

This paper describes the herbal remedies used by ethnic groups from Sonora, Mexico, for treatment of gastrointestinal diseases. Twelve types of these illnesses are cured using 85 different species which belong to 38 families. Thirty nine spp. are used to treat diarrhea, 28 for stomach-ache, 12 for constipation, 9 for intestinal parasites, 6 for indigestion, 3 for stomach or intestinal cancer, 3 for stomach inflammation and only 1 to treat gastrointestinal sicknesses, ulcers, gastritis, colitis and colic. Regarding the use of species of plant per ethnic group the following was observed: Mayo 47; Seri, 27; Yaqui, 13; Guarijio, 12, Pima, 5 and Papago, 3. The plants are used by two or more tribes, for the same or different illness but always related to the gastrointestinal system.

The International Adoption Project: population-based surveillance of Minnesota parents who adopted children internationally

OBJECTIVES

To conduct the first population-based surveillance in the United States of parents who adopted children from countries outside of the United States.

METHODS

A 556-item survey was mailed to 2,977 parents who finalized an international adoption in Minnesota between January 1990 and December 1998; 1,834 (62%) parents returned a survey.

RESULTS

Eighty-eight percent of the parents reported transracial adoptions (97% of the parents were white); 57% of the adopted children were Asian; 60% were female; and on average, the children were 18 months-old at the time of placement. Only 15% of the parents reported household annual incomes less than $50,000 and 71% reported they had college educations. Sixty-one percent traveled to their child's country of birth prior to the adoption. Almost three-quarters involved their children in experiences related to their birth countries and 98% would recommend international adoption. Three-quarters of the parents believe that parental leave was an issue for them as they adopted.

CONCLUSIONS

This is the first population-based survey of U.S. parents who have adopted internationally. The adoptive parents were socioeconomically different than birth parents in Minnesota and their families are most likely to be transracial. Because international adoption has become more prevalent, it is important to understand the strengths and needs of families that are created through this unique form of migration.

Signal transduction pathways that contribute to myeloid differentiation

The production of mature, differentiated myeloid cells is regulated by the action of hematopoietic cytokines on progenitor cells in the bone marrow. Cytokines drive the process of myeloid differentiation by binding to specific cell-surface receptors in a stage- and lineage-specific manner. Following the binding of a cytokine to its cognate receptor, intracellular signal-transduction pathways become activated that facilitate the myeloid differentiation process. These intracellular signaling pathways may promote myelopoiesis by stimulating expansion of a progenitor pool, supporting cellular survival during the differentiation process, or by directly driving the phenotypic changes associated with differentiation. Ultimately, pathways that drive the differentiation process converge on myeloid transcription factors, including PU.1 and the C/EBP family, that are critical for differentiation to proceed. While much is known about the cytokines, cytokine receptors and transcription factors that regulate myeloid differentiation, less is known about the precise roles that specific signaling mediators play in promoting myeloid differentiation. Recently, however, the application of novel pharmacologic inhibitors, siRNA strategies, and transgenic and knockout models has begun to shed light on the involvement and function of signaling pathways in normal myeloid differentiation. This review will discuss the roles that key signaling pathways and mediators play in myeloid differentiation.

The caregiving context in institution-reared and family-reared infants and toddlers in Romania

BACKGROUND

We assess individual differences in the caregiving environments of young children being raised in institutions in Romania in relation to developmental characteristics such as physical growth, cognitive development, emotional expression, and problem and competence behaviors.

METHOD

Videotaped observations of the child and favorite caregiver in their 'home' environment were coded for caregiving quality, and this was related to child characteristics. Child emotional reactivity was assessed during responses to interactional tasks. Cognitive development was assessed from child responses to the Bayley Scales of Infant Development. Data regarding problem behaviors and competence were obtained from caregiver report. Children reared in institutions were compared on all of these measures to never institutionalized children to assist gauging degree of impairment.

RESULTS

Children raised in institutions demonstrated marked delays in cognitive development, poorer physical growth, and marked deficits in competence. Individual differences in caregiving environment were associated with cognitive development, competence, and negative behavior among these young children being reared in institutions.

CONCLUSIONS

These data confirm previous findings regarding deficits associated with institutional care and extend our understanding of the impact of individual differences in caregiving quality on the development of young children in institutions.

International adoption: what is fact, what is fiction, and what is the future?

Despite the popularity of international adoption in North America and Western Europe as a means to build a family, the knowledge of health care professionals is often limited regarding the historical context of this phenomenon as well as the motivations and process experienced by adoptive parents. Although international adoption is viewed as an acceptable if not admirable method of forming kinships in accepting countries, opinions in the international community are mixed. Whether international adoptions increase or are drastically curtailed depends on addressing the misgivings that many countries have about placing their children abroad. Concerns center in two broad areas: sensitivity toward preservation of family and culture and whether the process has sufficient integrity to act in the best interests of children and birth parents.

Exclusion of oxygen from modified atmosphere packages limits beef rib and lumbar vertebrae marrow discoloration during display and storage

Visual and instrumental color (L*a*b* and reflectance from 400 to 700 nm) were used to evaluate packaging atmosphere as a way of minimizing beef marrow discoloration. In experiment 1, rib ends (n=24) packaged in 80% O(2)/20% CO(2) discolored more than ribs packaged in 100% N(2), which resulted in a relatively stable purplish marrow color through a 7-day display at 1 °C. In experiment 2, lumbar vertebrae (n=10) packaged in 80% O(2)/20% CO(2) had a rapid and significant discoloration within 24 h after packaging, likely because of the formation of methemoglobin. Conversely, vertebrae packaged in 80% N(2)/20% CO(2) and 0.4% CO/30% CO(2)/69.6% N(2) remained color stable during 2 and 6 weeks of storage at 4 °C, respectively. Exclusion of oxygen from MAP packages and the addition of low concentrations of CO minimized beef rib and lumbar vertebrae discoloration compared with high-oxygen MAP.

Response of lactating dairy cows to diets containing wet corn gluten feed or a raw soybean hull-corn steep liquor pellet

We evaluated effects of wet corn gluten feed (WCGF) and a novel product (SHSL) containing raw soybean hulls and corn steep liquor on performance and digestion in lactating dairy cows. In Experiment 1, 46 multiparous Holstein cows were assigned to control (C), WCGF (20% of diet DM), or SHSL (20% of diet DM). Diets were fed as a total mixed ration beginning after calving. The C diet contained (dry matter [DM] basis) 30% alfalfa hay, 15% corn silage, 32% corn, 9.3% whole cottonseed, 4.4% solvent soybean meal (SBM), and 3.3% expeller SBM. The WCGF replaced 10% alfalfa hay, 5% corn silage, and 5% corn grain, while expeller SBM replaced solvent SBM to maintain diet rumen undegradable protein. The SHSL replaced 10% alfalfa hay, 5% corn silage, 3% solvent SBM, and 2% corn. Dietary crude protein averaged 18.4%. Milk, energy-corrected milk (ECM), DM intake (DMI), and ECM/DMI were similar among diets during the first 13 wk of lactation. During wk 14 through 30 postpartum, WCGF and SHSL improved milk, ECM, milk component yield, and ECM/DMI. In Experiment 2, 6 cows were used to evaluate digestibility and rumen traits. Dry matter intake and total tract digestibilities of DM, fiber, and crude protein were not different among diets. Diets did not affect ruminal liquid dilution rate, pH, or concentrations of total volatile fatty acids or ammonia, but acetate:propionate was higher for C (3.38) than for WCGF (2.79) or SHSL (2.89). The WCGF and SHSL products can serve as alternative feedstuffs in diets fed to lactating dairy cattle.

Effect of glycine and vitamin supplementation on sulphur amino acid utilization by growing cattle

Effects of glycine (Gly) and B-vitamins on sulphur amino acid (AA) utilization were studied in growing steers maintained under conditions where methionine (Met) was first limiting. Conditions were generated by limit feeding a diet low in ruminally non-degraded protein and abomasally infusing an AA mixture limiting in Met. Retained N tended (p = 0.07) to improve when steers received 10 mg folate, 10 mg vitamin B6, and 0.10 mg vitamin B12 daily. Hepatic vitamin B12 (p = 0.08) and folate (p = 0.05) concentrations increased with vitamin supplementation. In another trial, factorial treatments were 2 or 5 g/day L-Met and 0 or 50 g/day Gly infused abomasally. Retained N increased (p < 0.05) in response to Met, and responses were numerically larger in the presence of supplemental Gly. In a different trial, factorial treatments were 0 or 2.4 g/day L-cysteine (Cys) and 0 or 40 g/day Gly. Retained N was not affected by Cys in the absence of Gly, but was increased by Cys when Gly was supplemented (interaction, p = 0.01). B-vitamin status may affect sparing of Met by Cys. Supplemental Gly improved responses to supplemental Met and Cys.

Ruminal and host adaptations to changes in frequency of protein supplementation

The effect of altering supplementation frequency on host N balance and key N transactions in the ruminal ecosystem were monitored. Four ruminally fistulated beef steers (BW = 513 kg; SEM = 6.5) were used in a 2 x 2 crossover design with two periods and two supplementation frequency treatments. Supplementation frequencies were 2 and 7 d/wk. Steers were fed tallgrass prairie hay (73.1% NDF, 5.3% CP) ad libitum. Supplement (42% CP; DM basis) was fed at 0.36% BW/d to steers supplemented 7 d/wk. Steers supplemented 2 d/wk received the same amount of supplement per week, but it was equally split among the two supplementation events. Steers supplemented 7 d/wk had higher forage (P < 0.02) and total digestible OM intake (P < 0.06), total N intake, fecal N excretion, and N retention. Although both supplementation frequencies were characterized by positive N balance, the decrease in N retention in the steers supplemented 2 d/wk was due to higher (P < 0.01) urinary N loss. Ruminal fluid was sampled at 0, 2, 4, 6, 12, 24, 48, and 72 h after supplementation beginning on a day when both treatments were supplemented. Frequency x hour interactions (P < 0.02) were observed for ruminal N metabolism criteria. Counts of peptide- and AA-fermenting bacteria peaked at 2 h and returned to nadir by 12 h for steers supplemented 7 d/wk. Steers supplemented 2 d/wk peaked at 6 h with a greater population and returned to nadir at 48 h. Ruminal ammonia concentrations followed a similar trend. Specific activity of ammonia production was lower (P < or = 0.05) immediately after supplementation for steers supplemented 2 d/wk, but by 12 h was the same as for 7 d/wk steers. Ruminal peptides and free AA peaked at 2 h for steers supplemented 2 d/wk and were generally higher (P < or = 0.05) during the first 6 h compared with steers supplemented 7 d/wk. Total VFA concentration was not different (P = 0.35) due to supplementation frequency. Frequency x hour interactions (P < 0.01) were observed for all molar proportions of VFA. The molar proportion of acetate and acetate:propionate ratio were lower (P < 0.01) and the molar proportions of propionate and butyrate were higher for steers supplemented 2 d/wk from 4 h to 24 h. In conclusion, forage use and N balance improved with supplementation 7 d/wk, but supplementation 2 d/wk was associated with some desirable shifts in select ruminal events that may contribute to moderating potential negative impacts of supplementing infrequently.

Decreased prostatic arachidonic acid in human prostatic carcinoma

OBJECTIVE

To measure prostatic and blood fatty acid composition in a large group of patients undergoing prostatectomy for benign or malignant prostate disease, as there is evidence linking arachidonic acid metabolism and prostate cancer through its role as an eicosanoid precursor, and earlier studies showed lower prostatic arachidonic acid content in a few patients.

PATIENTS AND METHODS

Prostatic phospholipid fatty acid composition was determined in prostate tissue from 173 patients undergoing prostate surgery, i.e. radical prostatectomy, cystoprostatectomy or transurethral resection (TURP). Blood fatty acid composition was determined in 99 of these patients and in 85 undergoing prostatic needle biopsy.

RESULTS

There was a significantly lower percentage of arachidonic acid in malignant than in benign portions of the prostate (15.2% vs 17%) in all patients assessed. The changes were greatest in those undergoing TURP for known prostate cancer (13.4% vs 17.2%), these patients having the greatest proportion of malignancy in the specimens. There were no consistent changes in blood fatty acid composition.

CONCLUSION

This is the first prospective study of arachidonic acids levels involving many consecutive patients undergoing prostate surgery for either benign or malignant disease. The lower prostatic arachidonic acid level is probably a result of the increased use of arachidonic acid for producing prostaglandins and/or leukotrienes. Further understanding of the cause and/or consequence of this finding might lead to a better understanding of prostate cancer.

Recent advances in the development of anticancer agents targeting cell death inhibitors in the Bcl-2 protein family

Hematopoietic malignancies frequently are characterized by defects in apoptosis signaling. This renders the malignant cells resistant to endogenous apoptotic stimuli, as well as exogenous stimuli, such as chemotherapy drugs and radiation. The defective apoptosis seen in human cancers often results from overexpression of antiapoptotic proteins in the Bcl-2 protein family, particularly Bcl-2 and Bcl-X(L). A great deal of effort is currently aimed at developing novel agents to inhibit the expression or function of these proteins. Antisense agents directed against Bcl-2 mRNA are showing considerable promise in clinical trials. In addition, detailed knowledge of the structures of Bcl-2 and Bcl-X(L), coupled with high-throughput and computer-assisted screening of chemical libraries, has led to the identification of a number of short peptides and small organic molecules capable of inhibiting Bcl-2 and Bcl-X(L) function. These newly described agents hold considerable promise for enhancing the chemo- and radiation sensitivities of Bcl-2- and Bcl-X(L)-overexpressing cancers. This review will highlight recent advances in the development and testing of agents targeting cell death inhibitors in the Bcl-2 protein family.

Differential activation of apoptosis regulatory pathways during monocytic vs granulocytic differentiation: a requirement for Bcl-X(L)and XIAP in the prolonged survival of monocytic cells

Neutrophils and monocytes/macrophages are derived from common progenitors, but exhibit markedly different lifespans. Differentiated neutrophils are short-lived and die rapidly by apoptosis, while monocytic cells are longer-lived. In this report we used the HL-60 cell line as a model system to identify differences in apoptotic pathways which might account for the differing lifespans of granulocytic vs monocytic cells. We observed that induction of granulocytic differentiation by retinoic acid led to robust activation of the executioner protease caspase-3, and early onset of apoptosis. By contrast, caspase-3 was not appreciably activated during phorbol 12-myristate 13-acetate (PMA)-induced monocytic differentiation, and apoptosis was delayed in these cells. Since the activation of caspase-3 is inhibited by members of the inhibitor of apoptosis (IAP) and Bcl-2 protein families, we investigated the expression of anti-apoptotic members of these families. Induction of monocytic differentiation led to marked upregulation of the IAP protein XIAP, as well as the Bcl-2 family member Bcl-X(L). During granulocytic differentiation the levels of XIAP progressively declined, while Bcl-X(L) levels remained unchanged. A different IAP protein, survivin, was downregulated during differentiation along either lineage, as was expression of Bcl-2. The upregulation of Bcl-X(L) during monocytic differentiation coincided with phosphorylation/activation of STAT3, a known activator of bcl-X gene transcription. Moreover, Bcl-X(L) upregulation was dependent on MEK/ERK signaling. Upregulation of XIAP proceeded in a MEK/ERK-independent fashion. Treatment with antisense Bcl-X(L) or XIAP oligonucleotides resulted in significant loss of viability in cells differentiating along the monocytic lineage. Together, these findings indicate that the levels of XIAP and Bcl-X(L) are regulated by distinct pathways during monocytic differentiation, and that upregulation of these proteins contributes to the increased longevity of cells in the monocytic lineage.

Type 1 fimbriae and extracellular polysaccharides are preeminent uropathogenic Escherichia coli virulence determinants in the murine urinary tract

Escherichia coli is the leading cause of urinary tract infections (UTIs). Despite the association of numerous bacterial factors with uropathogenic E. coli (UPEC), few such factors have been proved to be required for UTI in animal models. Previous investigations of urovirulence factors have relied on prior identification of phenotypic characteristics. We used signature-tagged mutagenesis (STM) in an unbiased effort to identify genes that are essential for UPEC survival within the murine urinary tract. A library of 2049 transposon mutants of the prototypic UPEC strain CFT073 was constructed using mini-Tn5km2 carrying 92 unique tags and screened in a murine model of ascending UTI. After initial screening followed by confirmation in co-infection experiments, 19 survival-defective mutants were identified. These mutants were recovered in numbers 101- to 106-fold less than the wild type in the bladder, kidneys or urine or at more than one site. The transposon junctions from each attenuated mutant were sequenced and analysed. Mutations were found in: (i) the type 1 fimbrial operon; (ii) genes involved in the biosyn-thesis of extracellular polysaccharides including group I capsule, group II capsule and enterobacterial common antigen; (iii) genes involved in metabolic pathways; and (iv) genes with unknown function. Five of the genes identified are absent from the genome of the E. coli K-12 strain. Mutations in type 1 fimbrial genes resulted in severely attenuated colonization, even in the case of a mutant with an insertion upstream of the fim operon that affected the rate of fimbrial switching from the 'off' to the 'on' phase. Three mutants had insertions in a new type II capsule biosynthesis locus on a pathogenicity island and were impaired in the production of capsule in vivo. An additional mutant with an insertion in wecE was unable to synthesize enterobacterial common antigen. These results confirm the pre-eminence of type 1 fimbriae, establish the importance of extracellular polysaccharides in the pathogenesis of UTI and identify new urovirulence determinants.