Intimin from enteropathogenic Escherichia coli restores murine virulence to a Citrobacter rodentium eaeA mutant: induction of an immunoglobulin A response to intimin and EspB.

The formation of attaching and effacing (A/E) lesions is central to the pathogenesis of enteropathogenic Escherichia coli (EPEC)-mediated disease in humans and Citrobacter rodentium (formerly C. freundii biotype 4280)-mediated transmissible colonic hyperplasia in mice. Closely related outer membrane proteins, known as intimins, are required for formation of the A/E lesion by both EPEC (Int(EPEC)) and C. rodentium (Int(CR)). A secreted protein, EspB (formally EaeB), is also necessary for A/E-lesion formation. Here we report that expression of a cloned Int(EPEC), encoded by plasmid pCVD438, restores murine virulence to an intimin-deficient mutant of C. rodentium DBS255. Replacement of Cys937 with Ala abolished the ability of the cloned EPEC intimin to complement the deletion mutation in DBS255. Ultrastructural examination of tissues from wild-type C. rodentium and DBS255(pCVD438)-infected mice revealed multiple A/E lesion on infected cells and loss of contact between enterocytes and basement membrane. Histological investigation showed that although both wild-type C. rodentium and DBS255(pCVD438) colonized the descending colon and induced colonic hyperplasia in orally infected 21-day-old mice, the latter strain adhered to epithelial cells located deeper within crypts. Nonetheless, infection with the wild-type strain was consistently more virulent, as indicated by a higher mortality rate. All the surviving mice, challenged with either wild-type C. rodentium or DBS255(pCVD438), developed a mucosal immunoglobulin A response to intimin and EspB. These results show that C. rodentium infection provides a relevant, simple, and economic model to investigate the role of EPEC proteins in the formation of A/E lesions in vivo and in intestinal disease.     

Body fluid changes, thirst and drinking in man during free access to water

To investigate whether human thirst and drinking during ad lib access to water occur in response to body fluid deficits, we obtained blood samples and visual analog scale thirst ratings from five healthy, volunteer, young men at hourly intervals and when they were thirsty during a normal working day. Although there were significant increases in ratings of thirst, pleasantness of drinking water, mouth dryness and unpleasantness of the taste in the mouth when subjects were thirsty enough to drink compared with intervening intervals, there were no concomitant changes in body fluid variables (microhematocrit, plasma osmolality and plasma sodium, potassium, protein and angiotensin II concentrations). Subjects drank mainly in association with eating and were not overhydrated as indicated by constantly hypertonic urine and significant tubular reabsorption of free water over the experimental period. The results indicate that during free access to water humans become thirsty and drink before body fluid deficits develop, perhaps in response to subtle oropharyngeal cues, and so provide evidence for anticipatory thirst and drinking in man.     

Prenatal diagnosis of sickle cell anemia. Hemoglobin electrophoresis versus DNA analysis

The prenatal diagnosis of sickle cell anemia (hemoglobin SS) can be established by DNA analysis using two highly sensitive techniques (Southern blot and polymerase chain reaction [PCR]). Hemoglobin electrophoresis provides a third, simpler and more rapid, technique to analyze blood from a fetus at risk for sickle cell anemia. The authors present examples of prenatal diagnostic studies using both DNA analysis techniques and hemoglobin electrophoresis. Hemoglobin electrophoresis of fetal hemolysate can provide a simple and rapid alternative method to PCR analysis for the prenatal exclusion of sickle cell anemia, and it is especially useful in cases in which rapid results are needed because of advanced gestational age.     

Null mutation in human ciliary neurotrophic factor gene confers higher body mass index in males

Ciliary neurotrophic factor (CNTF) administration reduces weight in leptin-resistant mice via the signalling pathway normally activated by leptin. A G>A null mutation in the CNTF gene results in complete absence of protein. We hypothesised that absence of CNTF could lead to diminished initiation of anorectic pathways, with consequent increase in body mass. In 575 Caucasian men aged 59-73 years, the A/A genotype (frequency 1.9%) was associated with a 10 kg increase in weight (P=0.03, 2 df) and 3 kg/m(2) greater BMI (P=0.02, 2 df). There was no effect in women. The CNTF G>A null mutation therefore confers a moderate effect on obesity in males of A/A genotype, who represent 1% of the general population.     

Adjustment in Childhood Brain Tumor Survival: Child, Mother, and Teacher Report

Examined the adjustment of 6- to 18-year-old children and adolescents(n = 38) 2 to 5 years postdiagnosis of brain tumor with respectto standardized measures of anxiety and depression; self-perceptions;and adaptive living skills. Child, mother, and teacher reportdata were used. Maternal adjustment (anxiety and depression,parenting stress) was also assessed. Children and adolescentssurviving brain tumors reported themselves to be generally withinthe normal range. However, maternal ratings of social problemswere higher than normative scores and significantly lower thannorms on social problems, scholastic competence, and communicationskills. Teacher ratings on the Teacher Rating Form were allwithin normal limits. Maternal adjustment measures were withinthe normal range, although the Parent-Child Dysfunctional Interactionsubscale of the Parenting Stress Index was elevated. No differencesin scores were found between children in regular and specialeducation, or between children who had received radiation andthose who did not. This sample of survivors of pediatric braintumors and their mothers had relatively mild problems in adjustment,supporting a competency-based view of the adaptation of pediatricpatients and their families.     

Stability of intracranial self-stimulation following hypophysectomy

The possibility of a hypothalamo-pituitary involvement in the intracranial self-stimulation phenomenon was investigated. Threshold and optimal stimulation currents were identified by means of the method of limits, in rats with bipolar electrodes implanted in the lateral hypothalamus. Total or sham hypophysectomies were performed after the establishment of these current values, and found to have no effect on reinforcing brain stimulation. It was concluded that a hypothalamo-pituitary mechanism does not subserve reinforcing brain stimulation.     

Home chaos: sociodemographic, parenting, interactional, and child correlates.

We conducted 2 studies to (a) establish the usefulness of the construct of home chaos, (b) investigate its correlates, and (c) determine the validity of the Confusion, Hubbub, and Order Scale (CHAOS) used to measure the construct in each study. Study 1 relied on a sample of European American preschoolers and their mothers and Study 2 on a sample of African American school-age children and their caregivers. Home chaos was associated with less effective parental discipline; elevated behavior problems, limited attentional focusing, and reduced ability to understand and respond to social cues in children; and reduced accuracy and efficiency in a cooperative parent-child interactional task, after controlling for potential confounds. It is concluded that (a) home chaos is not a proxy for adverse social or psychological circumstances but a useful construct in its own right; (b) home chaos is associated with multiple detrimental correlates in parents and children; and (c) the CHAOS scale provides an adequate and economical measure of home confusion and disorganization that should prove useful in clinical research with diverse populations.     

Studies on the serum proteins of chimeras: III. Detection of donor-type C′5 in allogeneic and congenic post-irradiation chimeras

Allogeneic and congenic post-irradiation chimeras were produced by bone marrow transfer from C′5 active donor mice into C′5 defective recipients. During the first 4 weeks after transfer many of the chimeras contained haemolytic complement activity in their sera. B6AF₁→A chimeras developed higher levels of activity than did B10D2 (new line)→ B10D2 (old line).

Spleen tissue, but not liver tissue, taken from the chimeric animals during this time period incorporated [¹⁴C]amino acid into MuB1 as demonstrated by autoradiography of immunoelectrophoretic patterns, suggesting localization of the active donor cells in the spleen rather than in the liver. Formation of donor-type IgG remained demonstrable for a more extended period after induction of chimerism than formation of MuB1.

A transplantable hepatoma in C57L/J, a C′5 active mouse strain, also incorporated [¹⁴C]amino acid into MuB1.