Ultraviolet radiation exposure to the face in patients with xeroderma pigmentosum and healthy controls: applying a novel methodology to define photoprotection behaviour.

BACKGROUND: In xeroderma pigmentosum (XP), the main means of preventing skin and eye cancers is extreme protection against ultraviolet radiation (UVR). Protection is most important for the face. OBJECTIVES: We aimed to assess how well patients with XP adhere to medical advice to protect against UVR by objectively estimating the mean daily dose of UVR to the face. METHODS: We objectively estimated the UVR dose to the face in 36 patients with XP and 25 healthy individuals over 3 weeks in the summer. We used a new methodology which combined UVR dose measurements from a wrist-worn dosimeter with an activity diary record of face photoprotection behaviour for each 15-min period spent outside. A protection factor was associated with each behaviour, and the data were analysed using a negative binomial mixed-effects model. RESULTS: The mean daily UVR dose (weighted for DNA damage capacity) to the face in the patients with XP was 0·13 standard erythemal doses (SEDs) (mean in healthy individuals = 0·51 SED). There was wide variation between patients (range < 0·01-0·48 SED/day). Self-caring adult patients had a very similar UVR dose to the face as cared-for patients (0·13 vs. 0·12 SED/day), despite photoprotecting much more poorly when outside, because the self-caring adults were outside in daylight much less. CONCLUSIONS: Photoprotection behaviour varies widely within the XP group indicating that nonadherence to photoprotection advice is a significant issue. The timing and duration of going outside are as important as photoprotective measures taken when outside, to determine the UVR exposure to the face. This new methodology will be of value in identifying the sources of UVR exposure in other conditions in which facial UVR exposure is a key outcome, particularly in patients with multiple nonmelanoma skin cancers.

Nitric oxide-releasing polyacrylonitrile disperses biofilms formed by wound-relevant pathogenic bacteria.

AIMS: To test the antimicrobial and antibiofilm properties of a nitric oxide (NO)-releasing polymer against wound-relevant bacterial pathogens. METHODS AND RESULTS: Using a variety of 96-well plate assay systems that include standard well plates and the minimum biofilm eradication concentration biofilm assay well plate, a NO-releasing polymer based on (poly)acrylonitrile (PAN/NO) was studied for antimicrobial and antibiofilm activity against the common wound pathogens Pseudomonas aeruginosa (PAO1), Staphylococcus aureus (Mu50) and Enterococcus faecalis (V583). The polymer was capable of dispersing single-species biofilms of Ps. aeruginosa as well as a more clinically relevant multispecies biofilm that incorporates Ps. aeruginosa along with Staph. aureus and Ent. faecalis. PAN/NO also synergistically enhanced the susceptibility of the multispecies biofilms to the common broad-spectrum antibiotic, ciprofloxacin. Multiple in vitro biocompatibility assays show that PAN/NO has limited potential for mammalian cytotoxicity. CONCLUSION: This study demonstrates the feasibility of utilizing the NO-releasing polymer, PAN/NO, to manage biofilms formed by wound-relevant pathogens, and provides proof-of-concept for use of this NO-releasing polymer platform across multiple disciplines where bacterial biofilms pose significant problems. SIGNIFICANCE AND IMPACT OF STUDY: In the clinical sector, bacterial biofilms represent a substantial treatment challenge for health care professionals and are widely recognized as a key factor in prolonging patient morbidity. This study highlights the potential role for the ubiquitous signalling molecule nitric oxide (NO) as an antibiofilm therapy.

Calibration of a Thomson parabola ion spectrometer and Fujifilm imaging plate detectors for protons, deuterons, and alpha particles.

A Thomson parabola ion spectrometer has been designed for use at the Multiterawatt (MTW) laser facility at the Laboratory for Laser Energetics (LLE) at the University of Rochester. This device uses parallel electric and magnetic fields to deflect particles of a given mass-to-charge ratio onto parabolic curves on the detector plane. Once calibrated, the position of the ions on the detector plane can be used to determine the particle energy. The position dispersion of both the electric and magnetic fields of the Thomson parabola was measured using monoenergetic proton and alpha particle beams from the SUNY Geneseo 1.7 MV tandem Pelletron accelerator. The sensitivity of Fujifilm BAS-TR imaging plates, used as a detector in the Thomson parabola, was also measured as a function of the incident particle energy over the range from 0.6 MeV to 3.4 MeV for protons and deuterons and from 0.9 MeV to 5.4 MeV for alpha particles. The device was used to measure the energy spectrum of laser-produced protons at MTW.

Socioeconomic status in relation to selected birth defects in a large multicentered US case-control study.

This study examined individual and household socioeconomic status (SES) in relation to phenotypes of neural tube defects, orafacial clefts, and conotruncal heart defects using data from the National Birth Defects Prevention Study with 2,551 nonmalformed liveborn controls and 1,841 cases delivered in 1997-2000. The individual SES was measured by maternal and paternal education, occupation, and household income. All individual SES measures were combined to create a household SES index. Elevated risks were found for maternal low education in association with anencephaly and dextrotransposition of the great arteries (dTGA) (adjusted odds ratios (AORs) > or = 1.4); paternal low education in association with anencephaly, cleft palate, tetralogy of Fallot (TOF), and dTGA (AORs > or = 1.4); low household income in association with TOF (AOR = 1.4, 95% confidence interval (CI): 0.8, 2.5); maternal operator/laborer occupation in association with cleft palate, TOF, and dTGA (AORs > or = 1.4); paternal operator/laborer occupation in association with spina bifida (AOR = 1.4, 95% CI: 1.0, 2.0); and either parent's unemployment in association with dTGA (AOR > or = 1.4). Subjects with the lowest household SES index had the greatest risks of all selected birth defects except TOF. This study reveals consistently increased risks of selected birth defects in association with household SES index but not individual SES measures.

Correlates of intake of folic acid-containing supplements among pregnant women.

OBJECTIVE: This study describes the timing and correlates of folic acid supplement intake among pregnant women. STUDY DESIGN: Data from 2518 women with estimated delivery dates from 1997 to 2000, collected for the National Birth Defects Prevention Study, a population-based case-control study, were analyzed. Multinomial logistic regression was used to identify correlates of supplement intake. RESULTS: Fifty-three percent of women began taking folic acid supplement during the periconceptional period, 35% during early pregnancy, and 8% during late pregnancy (ie, 3 months before through 1 month after conception, 2-3 months after conception, or more than 3 months after conception, respectively). Women who did not take folic acid supplement periconceptionally tended to be nonwhite, speak Spanish, have low education, be younger than 25 years old, be nulliparous, smoke, have no previous miscarriage and no fertility treatments, begin prenatal care and become aware of their pregnancy after the first trimester, have nonplanned pregnancies, and eat less breakfast cereal. CONCLUSION: This study identifies correlates of folic acid supplement intake, which may contribute to the design of interventions to improve intake during early pregnancy.

Do infants with major congenital anomalies have an excess of macrosomia?

BACKGROUND: Infants that develop congenital anomalies may also have an excess prevalence of macrosomia (birth weight > or =4,000 g). This may indicate that abnormalities of glycemic control play a role in the etiology of birth defects. This study was undertaken to determine whether all infants with congenital anomalies have an excess of macrosomia and whether it is confined to specific types of anomalies. METHODS: A case-control study was conducted, comparing the birth weights of 8,226 infants with congenital anomalies ascertained by the Texas Birth Defects Monitoring Division with those of 965,965 infants without birth defects. Odds ratios were calculated to determine the association between birth weight and congenital anomalies, for 45 specific defects, and for all these defects combined. RESULTS: For all 45 defects combined, a significant association occurred only in the highest birth weight category. Infants with congenital anomalies were more likely than infants without birth defects to have a birth weight > or =4,500 g (OR = 1.65; 95% CI = 1.39-1.96). Infants born with ventricular septal defects, atrial septal defects, ventricular hypertrophy, or anomalies of the great vessels were 1.5-2.5 times more likely to weigh > or =4,000 g than were infants without birth defects. Based on small numbers, a stronger excess of macrosomia was observed for infants with encephalocele, holoprosencephaly, anomalies of the corpus callosum, preaxial polydactyly, and omphalocele. CONCLUSIONS: Our data suggest that infants with specific congenital anomalies are more likely to be macrosomic than are infants without an anomaly. If these findings are confirmed, associations between macrosomia and specific types of birth defects may help to identify birth defects that are caused by alterations in glycemic control.

Patterns of first-year survival among infants with selected congenital anomalies in Texas, 1995-1997.

BACKGROUND: Few registry-based studies have investigated survival among infants with congenital anomalies. We conducted a registry-based study to examine patterns and probability of survival during the first year of life among infants with selected congenital anomalies. METHODS: Data from the Texas Birth Defects Monitoring Division were merged with linked birth-infant death files for 2,774 infants born January 1, 1995 to December 31, 1997, with at least 1 of 23 common anomalies. Deaths before the first birthday were assessed from infant death files. Kaplan-Meier was used to estimate first-year survival; first-year survival was assessed for specific anomalies and by the number of life-threatening anomalies. RESULTS: Overall, 80.8% of infants with these 23 anomalies survived the first year of life. We observed the highest survival rates for infants with gastroschisis (92.9%, 95% CI = 86.8, 96.3), trisomy 21 (92.3%, 95% CI = 89.5, 94.4) or cleft lip with or without cleft palate (87.6%, 95% CI = 84.0, 90.5). Infants with intermediate survival rates included those with microcephaly (79.7%; 95% CI = 73.6, 84.6), tetralogy of Fallot (75.0%; 95% CI = 65.5, 82.2), or with diaphragmatic hernia (72.8%; 95% CI = 61.8, 81.2). As expected, all infants with anencephaly and almost all infants with trisomy 13 or trisomy 18 died during the first year of life. First-year survival declined as the number of co-occurring life-threatening anomalies increased. CONCLUSIONS: Overall, first-year survival for infants with congenital anomalies was high. Additional population-based studies are needed to quantify improvements in first-year survival.

Neuropsychological assessment of battered women: a pilot study.

Mean performance of 19 battered women was significantly lower than that of 9 control women on the Halstead-Reitan Neuropsychological Battery, the Wechsler Memory Scale-Revised, and the Quick Neurological Screening Test. 58% of the battered women scored in the impaired range on the Halstead-Reitan Impairment Index; and 53% scored in the impaired range on the Quick Neurological Screening Test. More definitive research was recommended.

Frequency of prenatal diagnosis of birth defects in Houston, Galveston and the Lower Rio Grande Valley, Texas 1995.

BACKGROUND: Estimates of the proportion of birth defects diagnosed before birth exist for only a few types of birth defects and for a few geographic regions in the United States. This population-based study examines rates of prenatal diagnosis for previously unstudied birth defects in a new geographic region. METHODS: Active surveillance of 23 categories of birth defects among 111,902 infants born in 77 birthing hospitals in Texas in 1995 identified 852 infants or fetuses with major birth defects. Surveillance was conducted by the Texas Birth Defects Monitoring Program of the Texas Department of Health. Two regions were covered, the Houston/Galveston metropolitan area as well as the Lower Rio Grande Valley of Texas. Rates of prenatal diagnosis were evaluated for 23 different types of birth defects, using proportions and 95% confidence intervals. RESULTS: One third of the 852 infants or fetuses with birth defects were prenatally diagnosed. Diagnosis rates varied greatly depending on the type of birth defects and were lower among infants born to Black and Hispanic women. More than 60% of anencephaly, encephalocele, gastroschisis and trisomies 13 and 18 were diagnosed antenatally. Many of the fetuses that were electively terminated had birth defects or combinations of birth defects that were potentially lethal. Prevalence rates for birth defects generally do not include fetuses that die or are electively terminated before 20 weeks of gestation. Thus, 36% of anencephaly, 21% of omphalocele, 15% of encephalocele and between 7 and 10% of spina bifida, hydrocephaly, renal agenesis, and trisomies 13, 18, and 21 were not included in our published rates. CONCLUSIONS: Published rates for specific types of birth defects are spuriously low. This should be considered when investigating alleged clusters and comparing rates of birth defects across geographic areas. Since many elective abortions are for lethal or potentially lethal birth defects, a major effect of prenatal diagnosis is the resultant decrease in infant mortality attributable to birth defects.

Identification and characterization of aquaporin-2 water channel mutations causing nephrogenic diabetes insipidus with partial vasopressin response.

Congenital nephrogenic diabetes insipidus (NDI) is a rare disease caused most often by mutations in the vasopressin V2 receptor (AVPR2). We studied a family which included a female patient with NDI with symptoms dating from infancy. The patient responded to large doses of desmopressin (dDAVP) which decreased urine volume from 10 to 4 I/day. Neither the parents nor the three sisters were polyuric. The patient was found to be a compound heterozygote for two novel recessive point mutations in the aquaporin-2 (AQP2) gene: L22V in exon 1 and C181W in exon 3. Residue Cys181 in AQP2 is the site for inhibition of water permeation by mercurial compounds and is located near to the NPA motif conserved in all aquaporins. Osmotic water permeability (Pf) in Xenopus oocytes injected with cRNA encoding C181W-AQP2 was not increased over water control, while expression of L22V cRNA increased the Pf to approximately 60% of that for wild-type AQP2. Co-injection of the mutant cRNAs with the wild-type cRNA did not affect the function of the wild-type AQP2. Immunolocalization of AQP2-transfected CHO cells showed that the C181W mutant had an endoplasmic reticulum-like intracellular distribution, whereas L22V and wild-type AQP2 showed endosome and plasma membrane staining. Water permeability assays showed a high Pf in cells expressing wild-type and L22V AQP2. This study indicates that AQP2 mutations can confer partially responsive NDI.

Diversity of opines and opine-catabolizing bacteria isolated from naturally occurring crown gall tumors.

The diversity of opines from 43 naturally occurring crown gall tumors on several plant species was analyzed for the presence of agropine, chrysopine, iminodiacid, an unidentified leucinopine-like iminodiacid (IDA-B), mannopine, octopine, nopaline, DL- and LL-succinamopine, leucinopine and heliopine. Opine utilization patterns of agrobacteria and fluorescent pseudomonads resident in a tumor were then analyzed and compared for agreement with the opine isolated from that tumor. Nopaline was the most common opine found and was detected in tumors from cherry, blackberry, grape, and plum. Octopine was not found, although octopine-catabolizing bacteria were isolated from several tumors. A new, previously undescribed iminodiacid of the succinamopine-leucinopine type (provisionally designated IDA-B) was isolated from tumors of wild blackberry. Field tumors from apple, blueberry and grape yielded no detectable opines, even though opine-utilizing bacteria were present. Bacterial isolates from plum and cherry showed the best correspondence between the opine in tumors (nopaline) and the presence of bacteria that catabolized that opine. However, several unusual opine catabolic combinations were identified, including isolates that catabolized a variety of opines but were nonpathogenic. More variability was observed among isolates from field tumors on the remaining plant species. We isolated novel mannopine-nopaline type agrobacteria from field tumors of cherry, plum and blackberry that induced tumors containing either mannopine (plus agropine) or nopaline, but not both. Epidemiologically, the galled plants from an area were not of clonal origin (same Ti plasmid), indicating that the field tumors from a small area were incited by more than one type of Ti plasmid.

Hispanic origin and neural tube defects in Houston/Harris County, Texas. I. Descriptive epidemiology.

High prevalences of anencephaly and neural tube defects (NTDs) have recently been recorded for several Texas counties bordering Mexico. In addition, a few investigators have reported Hispanics to be at elevated risk for NTDs (anencephaly and spina bifida). Factors contributing to this risk have not been established. The authors conducted a study of NTDs in Harris County, Texas, to determine the prevalence of each defect. Prevalence was established by identifying cases among resident live births and fetal deaths (stillbirths at > or = 20 weeks) occurring from April 1, 1989, through December 31, 1991. Using multiple case ascertainment methods, 59 cases of anencephaly and 32 cases of spina bifida were detected, resulting in prevalences of 3.8 (95% confidence interval 2.9-4.9) and 2.0 (95% confidence interval 1.4-2.8) per 10,000 live births, respectively. The ratio of anencephaly prevalence to spina bifida prevalence was 2:1 in 1989, 1:1 in 1990, and 3:1 in 1991, with a significant difference in 1991. The female:male prevalence ratio was 1.0 for spina bifida and 2.2 for anencephaly, and was higher still for anencephaly among non-Hispanics (prevalence ratio = 5.6). For each defect, Hispanics experienced a prevalence approximately three times that of non-Hispanics. This ethnic difference was greater for males with anencephaly and for females with spina bifida. For anencephaly, the Hispanic:white/Anglo prevalence ratio (4.2) and the African-American:white/Anglo prevalence ratio (1.9) were greatly elevated and the Hispanic:African-American prevalence ratio (2.2) was similar, relative to comparable studies from the past two decades. The prevalence of anencephaly recorded for public hospitals (7.0 per 10,000) was three times greater than that for private hospitals (2.4 per 10,000). Spina bifida figures were similar for public (prevalence = 2.2 per 10,000) and private (prevalence = 2.0 per 10,000) hospitals. A significantly higher prevalence of both defects was documented among Hispanics in Harris County. The higher anencephaly rates among Hispanics, African-Americans, and those using public hospitals in an era of NTD screening, prenatal diagnosis, and elective pregnancy termination suggest that socioeconomic and perhaps cultural/religious factors might influence the recorded birth prevalence of this defect in particular groups.

Hispanic origin and neural tube defects in Houston/Harris County, Texas. II. Risk factors.

Several investigators have reported Hispanics to be at elevated risk for neural tube defects (anencephaly and spina bifida). Factors contributing to this risk have not been established. The authors conducted a case-control study of neural tube defects (NTDs) among births occurring in Harris County, Texas, from April 1, 1989, through December 31, 1991. Through the use of multiple ascertainment methods, 59 cases of anencephaly and 32 cases of spina bifida were detected. Controls (n = 451) were sampled for the same time period from Harris County vital records. Regardless of how Hispanic ethnicity was classified, having a Hispanic parent was a risk factor for both anencepahly and spina bifida. The primary etiologic question was whether increased NTD risk in Hispanics is explained by maternal diabetes or by other factors (e.g., maternal birthplace, prenatal care, reproductive history, age, socioeconomic status). Mexico-born Hispanics were no more likely than Texas-born Hispanics to deliver a fetus or infant with an NTD. Having a Hispanic mother was a risk factor for anencephaly among infants born to women with early prenatal care (odds ratio (OR) = 4.54, 95% confidence interval (CI) 2.21-9.40) but not for those born to latecomers. Earlier prenatal care seemed "protective" for non-Hispanics (OR = 0.18, 95% CI 0.06-0.65) but not for Hispanics. After simultaneous adjustment for eight variables in multivariate analysis, having a Hispanic (versus non-Hispanic) mother remained a strong risk factor for both anencephaly (OR = 2.58, 95% CI 1.19-5.61) and spina bifida (OR = 3.71, 95% CI 1.48-9.31). Any previous pregnancy termination/fetal loss was also associated with anencephaly in a final logistic regression model (OR = 2.48, 95% CI 1.20-5.10), and having a teenage mother (aged < 20 years) approached significance (OR = 2.21, 95% CI 0.92-5.31). "Hispanic mother" was the only study variable significantly associated with spina bifida in multivariate analysis. Results for diabetes suggested no association with anencephaly (OR = 1.24, 95% CI 0.25-6.17). An increased risk of NTDs among Hispanics remained after controlling for other factors. For anencephaly, this risk might be partially explained by economic and cultural differences between Hispanics and non-Hispanics, and the effect of these factors on rates of prenatal diagnosis and elective pregnancy termination.

Genetic analysis of nonpathogenic Agrobacterium tumefaciens mutants arising in crown gall tumors.

Little is known about the effect of the host on the genetic stability of bacterial plant pathogens. Crown gall, a plant disease caused by Agrobacterium tumefaciens, may represent a useful model to study this effect. Indeed, our previous observations on the natural occurrence and origin of nonpathogenic agrobacteria suggest that the host plant might induce loss of pathogenicity in populations of A. tumefaciens. Here we report that five different A. tumefaciens strains initially isolated from apple tumors produced up to 99% nonpathogenic mutants following their reintroduction into axenic apple plants. Two of these five strains were also found to produce mutants on pear and/or blackberry plants. Generally, the mutants of the apple isolate D10B/87 were altered in the tumor-inducing plasmid, harboring either deletions in this plasmid or point mutations in the regulatory virulence gene virG. Most of the mutants originating from the same tumor appeared to be of clonal origin, implying that the host plants influenced agrobacterial populations by favoring growth of nonpathogenic mutants over that of wild-type cells. This hypothesis was confirmed by coinoculation of apple rootstocks with strain D10B/87 and a nonpathogenic mutant.

Neurons in the lateral subdivision of the habenular complex mediate the hormonal onset of maternal behavior in rats.

Expanding on research showing that radio-frequency-induced lesions of the habenular complex disrupt the hormonal onset of maternal behavior in rats, we explored the importance of neurons in the lateral (Lhb) subdivision of the habenular complex for the onset of maternal behavior. On Day 12 of pregnancy, bilateral cytotoxic lesions were produced in the Lhb with kainic acid or, as a control, just dorsal in the medial hippocampus. A 3rd group had radio-frequency-induced Lhb and medial (Mhb) lesions. On Day 16 of pregnancy, Ss were hysterectomized-ovariectomized, given estradiol, and tested 48 hr later for 10 days. Neuroanatomical tracing with fluoro-gold was then used to directly quantify the extent and location of Lhb neuron loss and to verify that Mhb neurons were intact. Cytotoxic lesions of the entire Lhb prevented the onset of all components of maternal behavior compared with controls. Results show that neurons in the Lhb, not the Mhb, are important for onset of maternal behavior in rats.

Investigation of a measles outbreak in a fully vaccinated school population including serum studies before and after revaccination.

A measles outbreak in early 1989 among approximately 4200 students at a high school and two intermediate schools in suburban Houston, TX, was investigated to evaluate reasons for vaccine failure and to predict the efficacy of a booster dose of measles vaccine. Seventy-seven cases occurred (71 at the high school, 6 at intermediate schools; attack rate, 3.2 and 0.3%, respectively). Vaccination in the first year of life an 13 to 14 years since last vaccination were independent risk factors for being a case. Forty-three (18%) of 239 sera collected from students just before revaccination during the outbreak were negative by enzyme immunoassay; a neutralization assay confirmed these 43 lacked antibody predicting protection against measles infection. Of 43 enzyme immunoassay-negative students 24 gave another blood sample 9 to 10 months after revaccination. Revaccination appeared to reduce the portion of all students with neutralization titers predicting susceptibility to measles illness with rash from 7.9% to 3.0% and left the portion predicted to be susceptible to illness without rash unchanged (45%).

Preliminary data on voluntary food sharing in brown capuchin monkeys.

Spontaneous interactions over fruits and vegetables were observed in a captive group of Cebus apella. The group lacked fully grown males; 3 adult females dominated the remaining 11 individuals, most of which were adolescents and late juveniles. Apart from expressions of interest and unsuccessful attempts to claim food, interactions over food included two types of interindividual food transfer: forced claims (i.e., involuntary transfers) and peaceful sharing. These two categories represented 7.2% and 20.3% of 3,389 observed food interactions, respectively. Sharing of food was subdivided into four categories; the most frequent category was the collection of discarded food items from within reach of the possessor, and the least frequent was active giving of food items by the possessor. The voluntary nature of food transfers was further investigated in an experiment in which two monkeys were placed in adjacent cages with a wire-mesh partition between them. One subject received food; the other did not. Although this setup made it easy for possessors to prevent food transfers, sharing occurred in all 18 tests on different combinations of individuals. In 10 of the tests, possessors were observed to actively push food through the mesh partition to their partner. © 1993 Wiley-Liss, Inc.

Contingency interaction analysis in psychotherapy.

This article introduces (a) a computerized coding procedure that rates words and utterances in terms of emotion, cognition, and contract and (b) a contingency method of analyzing verbal interactions. Using transcripts of sessions conducted by 3 master therapists with 1 client, the rating procedure and contingency correlation analyses supported the study's hypotheses. Therapists' utterances were characterized by significantly different amounts of emotion, cognition, and contracts, indicating that communication styles varied in the relative emphasis placed on these attributes. Differences suggest that the therapists responded differently to emotional, cognitive, and contract utterances and that the client's responses were different across the 3 therapist interviews. Split halves of the interviews within therapists and within client sessions were not different, providing further evidence of reliability of the coding and contingency procedures.

Growth of Octopine-Catabolizing Pseudomonas spp. under Octopine Limitation in Chemostats and Their Potential To Compete with Agrobacterium tumefaciens.

The growth characteristics of five octopine-catabolizing pseudomonads have been determined in batch and continuous cultures. All five strains belonged to rRNA homology group I and showed a more psychrotrophic growth pattern than did Agrobacterium tumefaciens B6 and ATCC 15955. In chemostats limited by octopine, either as the source of carbon and nitrogen or the sole source of nitrogen, maximum specific growth rates and substrate affinities were lower than those in chemostats limited by glutamate. These growth dynamics were similar to those observed for Agrobacterium strains B6 and ATCC 15955 even though the catabolic genes and pathways are believed to be different in the two genera. An analysis of the yields in octopine-limited chemostats indicated that the use of octopine as the sole source of carbon and nitrogen was grossly inefficient. Octopine and presumably lysopine and octopinic acid provided a better source of nitrogen than of carbon. One of the Pseudomonas fluorescens strains, E175D, was able to produce its highest yield on octopine as a nitrogen source. Competition models formulated on pure culture parameters indicated that two of the Pseudomonas spp. would dominate A. tumefaciens B6 and ATCC 15955 when in simple competition for octopine as a limiting substrate.