The mouse Mid1 gene: implications for the pathogenesis of Opitz syndrome and the evolution of the mammalian pseudoautosomal region

We have recently reported isolation of the gene responsible for X- linked Opitz G/BBB syndrome, a defect of midline development. MID1 is located on the distal short arm of the human X chromosome (Xp22. 3) and encodes a novel member of the B box family of zinc finger proteins. We have now cloned the murine homolog of MID1 and performed preliminary expression studies during development. Mid1 expression in undifferentiated cells in the central nervous, gastrointestinal and urogenital systems suggests that abnormal cell proliferation may underlie the defect in midline development characteristic of Opitz syndrome. We have also found that Mid1 is located within the mouse pseudoautosomal region (PAR) in Mus musculus , while it seems to be X- specific in Mus spretus. Therefore, Mid1 is likely to be a recent acquisition of the M. musculus PAR. Genetic and FISH analyses also demonstrated a high frequency of unequal crossovers in the murine PAR, creating spontaneous deletion/duplication events involving Mid1. These data provide evidence for the first time that genetic instability of the PAR may affect functionally important genes. In addition, we show that MID1 is the first example of a gene subject to X-inactivation in man while escaping it in mouse. These data contribute to a better understanding of the molecular content and evolution of the rodent PAR.      

Antibody and cellular immune responses to microfilarial antigens in ferrets experimentally infected withBrugia malayi

Eleven of 15 ferrets experimentally infected withBrugia malayi became amicrofilaremic after a brief patency; only four ferrets remained patent after 6 months of infection and two of these ferrets developed a high, persistent microfilaremia. Blastogenic responses of peripheral blood lymphocytes to antigens of microfilariae (mf), assayed in vitro, demonstrated an antigen sensitivity at prepatent, patent and postpatent periods of infection. Lymphocytes from ferrets with high microfilaremia had elevated background responses in culture which were directly correlated with the number of circulating mf. This background response was attributed to antigenic stimulation by mf present in the lymphocyte cultures; addition of mf to cultures of lymphocytes from postpatent ferrets induced responses equivalent to those observed in microfilaremic ferrets. Lymphocyte responses to the mitogen, concanavalin A, did not differ significantly among microfilaremic, amicrofilaremic and uninfected ferrets. Antibody in IgG to antigens of mf measured by ELISA and by immunoblots from SDS-PAGE showed similar patterns of response in ferrets which became amicrofilaremic and in the few ferrets which remained microfilaremic. Prausnitz-Kustner tests demonstrated no consistent differences in titers to microfilarial antigens between patent and amicrofilaremic ferrets. The results suggest a high level of immune responsiveness to antigens of mf in infected ferrets with no evidence of immunosuppression associated with prolonged microfilaremia or of major changes in immune responses with development of amicrofilaremic infections.     

Lymphocytic Hypophysitis Presenting as a Pituitary Tumor in a 63-Year-Old Man

This report describes a case of lymphocytic hypophysitis in a 63-year-old man who presented with symptoms of a pituitary mass lesion associated with hypothyroidism and hypogonadism. Postoperative endocrinological testing demonstrated gonadotropic, thyrotropic, and corticotropic hypopituitarism, and the patient was commenced on replacement therapy with hydrocortisone and levothyroxine. Histological examination of the pituitary tissue obtained by transsphenoidal surgery revealed lymphocytic hypophysitis without evidence of a pituitary adenoma. The vast majority of patients with lymphocytic hypophysitis are women particularly during pregnancy and the puerperium. Until recently only four men were reported in the literature. The pathogenesis of lymphocytic hypophysitis is uncertain but autoimmune mechanisms are possibly involved.     

Activation of mucosal Vβ3+ T cells and tissue damage in human small intestine by the bacterial superantigen,Staphylococcus aureus enterotoxin B

Staphylococcus aureus enterotoxin B (SEB) was added to explants of fetal human intestine in organ culture or administered into the lumen of fetal small intestine prior to culture. Both routes produced a massive increase in lamina propria T cells expressing Vβ33, and to a lesser extent, those expressing Vβ5 and Vβ12. SEB-activated lamina propria T cells produced interleukin-2 and interferon-Y and T cell activation was accompanied by tissue damage, which was inhibited by FK506.     

The effects of hip contact aberrations on stress patterns within the human femoral head

A two-dimensional finite element model incorporating cancellous bone inhomogeneity is used to study femoral head stress alterations caused by changes from the usual articular contact patterns. The contact stress distributions, calculated from an earlier mathematical analysis by Greenwald and O'Connor (16), are found to influence not only the adjacent subchondral bone, but relatively distant parts of the head as well. Both abnormally large joint incongruity and abnormally low cartilage compliance cause load to shift away from the superior “weight-bearing” area, out toward the periphery of the contact region. As a consequence, transverse compressive stresses, which are of appreciable magnitude but which do not contribute to weight bearing, are built up throughout much of the superior and central portions of the femoral head. Most small changes in the overall cartilage thickness or in its thickness distribution, when considered in isolation from hip compliance changes, have only minor effects on the internal stress distribution. An important exception is cartilage thinning at the superior margin, which can result in abrupt longitudinal compressive stress concentrations. It is suggested that such alterations of the normal patterns of stress transmission may contribute to sclerosis or to the formation of osteophytes or cysts in the osteoarthritic hip. This study was aided by grants from the Easter Seal Research Foundation (#N7739), the National Science Foundation (#ENG78-05451), the Barra Foundation, Inc., and the Western Pennsylvania Chapter of the Arthritis Foundation. The authors wish to acknowledge the excellent service provided by the University of Pittsburgh Computer Center. The assistance of Mr. Gary E. Graf and Mrs. Diana W. Montgomery are also appreciated.     

Branched-chain aminotransferase deficiency in Chinese hamster cells complemented by two independent genes on human chromosomes 12 and 19

Branched-chain aminotransferase (BCT) catalyzes the reversible transamination of the branched-chain -keto acids to the branched-chainl-amino acids. Since branched-chainl-amino acids (l-isoleucine,l-leucine, andl-valine) are essential for cell growth, cells which lack BCT were unable to proliferate in media containing -keto acids in place of the correspondingl-amino acids. CHW-1102, a Chinese hamster cell line, lacks BCT and does not grow in -keto acid media. Somatic cell hybrids were made by the fusion of CHW-1102 (HPRT^–) with several human cell lines and isolated on HAT medium. Growth assays of hybrid clones on -keto acid selection media independent of the HAT selection medium indicated two cell hybrid phenotypes: either (1) the hybrid clone, like the parental CHW-1102, could not utilize -keto acid media, or (2) the hybrid could proliferate on all three -keto acid media. The ability of hybrid cells to proliferate on -keto acid media correlated with the presence of either of two human genes which independently complemented the Chinese hamster deficiency. Two human genes, BCT1 assigned to chromosome 12 and BCT2 assigned to chromosome 19, were demonstrated to code for the expression of two molecular forms of BCT.A preliminary abstract of this work has been presented at the Human Gene Mapping Workshop V [Naylor, S.L. and Shows, T.B. (1979).Cytogenet. Cell Genet. 25:191–192].     

Microelectrode amplifier with improved method of input-capacitance neutralisation

A circuit is described which allows the input capacitance of an f.e.t. input integrated circuit to be used both as the feedback capacitance to neutralise the total input capacitance and to inject current pulses into the input. Compared with the conventional method of adding discrete capacitors to perform these functions, this design results in a lower total capacitance at the input, which reduces the high-frequency noise generated by the amplifier and facilitates the achievement of a low effective capacitance. A modified version having an ultralow (0·1pA) input current, for use with ion-sensitive microelectrodes, is also described.     

Cell cultures for diagnosis of arbovirus infections in livestock and wildlife

Summary Arboviruses can be isolated in serially propagated cells derived from various vertebrates and invertebrates. Cell cultures can be used for direct detection of antigen by fluorescent antibody and enzyme-linked immunosorbent assays, for nucleic acid hybridization, and for visualization of viruses with electron microscopy. Reagents for enzyme-linked immunosorbent assays for IgM and IgG antibodies, hemagglutination-inhibition, complement fixation, and serum dilution-plaque reduction neutralization tests can be prepared in cell cultures infected with these viruses. Thus, cell cultures can be used as laboratory hosts for essentially all isolation, identification, and serodiagnostic procedures for arboviruses. This paper outlines current methods for diagnosis of arbovirus infections in livestock and wildlife, describes certain of these techniques, and provides references for others.     

Risk factors for wheezing in a subtropical environment: role of respiratory viruses and allergen sensitization

BACKGROUND: Risk factors for acute wheezing among children in subtropical areas are largely unknown. OBJECTIVE: To investigate the role of viral infections, allergen sensitization, and exposure to indoor allergens as risk factors for acute wheezing in children 0 to 12 years old. METHODS: One hundred thirty-two children 0 to 12 years of age who sought emergency department care for wheezing and 65 children with no history of wheezing were enrolled in this case-control study. Detection of respiratory syncytial virus antigen, rhinovirus and coronavirus RNA, adenovirus, influenza, and parainfluenza antigens was performed in nasal washes. Total IgE and specific IgE to mites, cockroach, cat, and dog were measured with the CAP system. Major allergens from mites, cockroach, cat, and dog were quantified in dust samples by ELISA. Univariate and multivariate analyses were performed by logistic regression. RESULTS: In children under 2 years of age, infection with respiratory viruses and family history of allergy were independently associated with wheezing (odds ratio, 15.5 and 4.2; P = .0001 and P = .008, respectively). Among children 2 to 12 years old, sensitization to inhalant allergens was the major risk factor for wheezing (odds ratio, 2.7; P = .03). High-level allergen exposure, exposure to tobacco smoke, and lack of breast-feeding showed no association with wheezing. CONCLUSIONS: Some risk factors for wheezing previously identified in temperate climates were present in a subtropical area, including respiratory syncytial virus infection in infants and allergy in children older than 2 years. Rhinovirus was not associated with wheezing and did not appear to be a trigger for asthma exacerbations.