A new mutation in the promoter region of the PAX8 gene causes true congenital hypothyroidism with thyroid hypoplasia in a girl with Down's syndrome

<b>Background:</b> Thyroid dysfunction is common in newborn infants with Down's syndrome (DS), but defects causing classic thyroid dysgenesis (TD) with permanent congenital hypothyroidism (CH) have not been described.<p></p> <b>Objective:</b> We studied a girl with DS and CH who had a mutation in the promoter sequence of the PAX8 gene.<p></p> <b>Results:</b> A female infant was found to have trisomy 21 and CH, with a venous thyrotropin (TSH) of >150 mU/L and a free thyroxine (fT4) of 15.1 pmol/L (day 12). Thyroid peroxidase antibodies and thyroglobulin antibodies were elevated. Scintigraphy showed normal uptake, but ultrasound identified a small gland with heterogenous echotexture and cystic changes. Sequence analysis of the PAX8 gene revealed a new heterozygous maternally inherited mutation (−3C>T) close to the transcription initiation site. Electromobility shift assay studies of the wild type and the mutant PAX8 sequence incubated with nuclear extracts from PCCL3 cells exhibited that the sequence at position −3 is not involved in specific protein binding. However, the mutant PAX8 promoter showed a significantly reduced transcriptional activation of a luciferase reporter gene in vitro tested in HEK, PCCL3, as well as in HeLa cells, indicating that this mutation is very likely to lead to reduced PAX8 expression.<p></p> <b>Conclusions:</b> The persistent CH in this patient with DS is likely to be attributable to the diminished PAX8 expression due to a new heterozygous mutation in the PAX8 promoter sequence. Our case shows that true CH may occur in DS, as in the general population. Furthermore, it is possible that the trisomy 21 itself may have resulted in a more severe phenotypic expression of the PAX8 mutation in the child than the mother

Determination of thyroid volume in infants with suspected congenital hypothyroidism—the limitations of both subjective and objective evaluation

Objective: To compare two methods of assessing gland size on thyroid ultrasound in newborn infants with suspected congenital hypothyroidism (CH). Methods: Images from infants with eutopic glands referred between 2007 and 2013 were evaluated blind by two sets of observers. Subjective gland size was categorised as small, borderline-small, normal, borderline-large and large. Objective gland volume, calculated as the sum of each lobe using the prolate ellipsoid formula (length x width x depth x π/6), was put into corresponding categories: <0.8, 0.81–1.0, 1.1– <2.2, 2.2–2.4 and >2.4 ml, derived from normative Scottish data. Results: Of 36 infants, permanent CH was present in 17, transient CH in 17, status uncertain in 2. Mean (SD) intraobserver error for thyroid volume measurement was 0.11 (0.23) ml [8.3%]. Subjective assessment by two observers was discordant in only four (10.8%) infants. However, subjective vs objective evaluation was discordant in 14 (39%). Eight (three permanent, five transient CH) had large glands subjectively but normal glands objectively; and six (four transient CH) had normal glands subjectively but small glands objectively. The former infants all showed a single flattened curve to the anterior thyroid margin, giving an impression of bulkiness. Gland shape was normal in the latter infants. Conclusion: Neither subjective nor objective evaluation predicts permanent vs transient CH. Altered gland shape may confound both methods, and undermine use of the conventional formula for measuring lobe volume. Advances in knowledge: Until more refined methods are available for assessing thyroid size, both subjective and objective evaluation are recommended in CH

\u3ci\u3eEscherichia coli\u3c/i\u3e O157:H7 in the gallbladders of experimentally infected calves

Fifteen weaned calves (age 89–141 days) were treated with dexamethasone (0.25 mg/kg, IV) for 3 days before, the day of, and the day after inoculation with 10 colony-forming units of either Escherichia coli O157:H7 (strain 86-24, which produces Shiga toxin 2 and intimin; n=13) or nonpathogenic E. coli (strain 123, which does not produce Shiga toxin or intimin; n=2). All calves were necropsied 4 days after inoculation. Histologic lesions of attaching and effacing bacteria were observed in the large intestine (12/13) and in the gallbladder mucosa (5/13) of calves inoculated with E. coli 86-24. Cholecystitis was present in 12 of 13 calves that received E. coli 86-24. Inoculum bacteria were recovered from the distal colons or feces (13/13) and gallbladders (3/4) of calves inoculated with 86-24

\u3ci\u3eEscherichia coli\u3c/i\u3e O157:H7 Causes More-Severe Systemic Disease in Suckling Piglets than in Colostrum-Deprived Neonatal Piglets

Our objective was to determine if suckling neonatal piglets are susceptible to enterohemorrhagic Escherichia coli (EHEC) O157:H7 disease. Surprisingly, EHEC O157:H7 caused more-rapid and more-severe neurological disease in suckling neonates than in those fed an artificial diet. Shiga toxin-negative O157:H7 did not cause neurological disease but colonized and caused attaching-and-effacing intestinal lesions

Early Attachment Sites for Shiga-Toxigenic \u3ci\u3eEscherichia coli\u3c/i\u3e O157:H7 in Experimentally Inoculated Weaned Calves

Weaned 3- to 4-month-old calves were fasted for 48 h, inoculated with 1010 CFU of Shiga toxin-positive Escherichia coli (STEC) 0157:H7 strain 86-24 (STEC 0157) or STEC 091:H21 strain B2F1 (STEC 091), Shiga toxin-negative E. coli 0157:H7 strain 87-23 (Stx- 0157), or a nonpathogenic control E. coli strain, necropsied 4 days postinoculation, and examined bacteriologically and histologically. Some calves were treated with dexamethasone (DEX) for 5 days (3 days before, on the day of, and 1 day after inoculation). STEC 0157 bacteria were recovered from feces, intestines, or gall bladders of 74% (40/55) of calves 4 days after they were inoculated with STEC 0157. Colon and cecum were sites from which inoculum-type bacteria were most often recovered. Histologic lesions of attaching-and-effacing A/E 0157+ bacteria were observed in 69% (38/55) of the STEC 0157-inoculated calves. Rectum, ileocecal valve, and distal colon were sites most likely to contain A/E 0157+ bacteria. Fecal and intestinal levels of STEC 0157 bacteria were significantly higher and A/E 0157+bacteria were more common in DEX-treated calves than in nontreated calves inoculated with STEC 0157. Fecal STEC 0157 levels were significantly higher than Stx- 0157, STEC 091, or control, or control E. coli; only STEC 0157 cells were recovered from tissues. Identifying the rectum, ileocecal valve, and distal colon as early STEC 0157 colonization sites and finding that DEX treatment enhances the susceptibility of weaned calves to STEC 0157 colonization will facilitate the identification and evaluation of interventions aimed at reducing STEC 0157 infection in cattle

Mutations in the NKX2.5 Gene and the PAX8 Promoter in a Girl with Thyroid Dysgenesis

A girl with thyroid dysgenesis had two gene mutations resulting in two defective transcriptional factors important for thyroid development

Comparative Pathogenicity of \u3ci\u3eEscherichia coli\u3c/i\u3e O157 and Intimin-Negative Non-O157 Shiga Toxin-Producing \u3ci\u3eE. coli\u3c/i\u3e Strains in Neonatal Pigs

We compared the pathogenicity of intimin-negative non-O157:H7 Shiga toxin (Stx)-producing Escherichia coli (STEC) O91:H21 and O104:H21 strains with the pathogenicity of intimin-positive O157:H7 and O157:H- strains in neonatal pigs. We also examined the role of Stx2d-activatable genes and the large hemolysinencoding plasmid of O91:H21 strain B2F1 in the pathogenesis of STEC disease in pigs. We found that all E. coli strains that made wild-type levels of Stx caused systemic illness and histological lesions in the brain and intestinal crypts, whereas none of the control Stx-negative E. coli strains evoked comparable central nervous system signs or intestinal lesions. By contrast, the absence of intimin, hemolysin, or motility had little impact on the overall pathogenesis of systemic disease during STEC infection. The most striking differences between pigs inoculated with non-O157 STEC strains and pigs inoculated with O157 STEC strains were the absence of attaching and effacing intestinal lesions in pigs inoculated with non-O157:H7 strains and the apparent association between the level of Stx2d-activatable toxin produced by an STEC strain and the severity of lesions

Selective Pituitary Resistance to Thyroid Hormone Produced by Expression of a Mutant Thyroid Hormone Receptor β Gene in the Pituitary Gland of Transgenic Mice

Resistance to thyroid hormone (RTH) has been subdivided into generalized resistance (GRTH) and pituitary resistance (PRTH) based on the clinical impression of absence or presence of thyrotoxicosis. However, due to lack of objective clinical and genetic criteria, the existence of PRTH as a distinct entity became controversial. To determine what the phenotype would be if RTH was confined to the pituitary, a transgenic mouse was developed in which expression of the mutant thyroid hormone receptor (TR) β (G345R) was targeted to the pituitary thyrotrophs by placing it downstream of the mouse thyrotropin β promoter. This construct exhibited an antagonistic effect on the thyroid hormone-dependent transactivation, mediated through the wild-type TRβ1, only when cotransfected with the thyrotroph embryonic factor in a heterologous cell line. As expected the transgene was transcribed predominantly in the pituitary gland but not in liver. These mice showed a significant, though modest, increase in serum T4concentration. A decrease in the serum cholesterol was observed in keeping with the selective tissue hyposensitivity to thyroid hormone