A 50-kDa membrane protein mediates sialic acid-independent binding and infection of conjunctival cells by adenovirus type 37

The ocular tropism of adenovirus type 37 (Ad37) does not correlate with the wide distribution of the 46-kDa coxsackievirus and adenovirus receptor (CAR), the major receptor for most adenovirus serotypes. We previously found that Ad37 infects and binds well to conjunctival cells (Chang C), but poorly to lung epithelial (A549) cells that express CAR and hypothesized that this serotype uses a distinct receptor that is selectively expressed on conjunctival cells. To test this, we produced particles of a fiber-deleted Ad5 vector containing the Ad37 fiber protein. The "pseudotyped" vector infected Chang C cells better than A549 cells using a CAR-independent pathway. Ad37 binding was calcium-dependent and was abolished by protease digestion of cell surface proteins. Using a virus overlay protein blot assay (VOPBA), we detected calcium-dependent Ad37 binding to 50- and 60-kDa membrane proteins on permissive Chang C cells. In contrast, calcium-dependent binding was detected with only the 60-kDa protein on nonpermissive A549 cells. Ad19p, a closely related serotype that failed to bind to conjunctival cells, recognized the 60-kDa, but not the 50-kDa, protein. Ad37 has been reported to use sialic acid instead of CAR as a cell receptor on A549 cells. Pretreatment of Chang C cells with neuraminidase abolished Ad37 binding to only the 60-kDa protein, suggesting that sialic acid mediates Ad37 binding to the 60-kDa protein. The pseudotyped Ad37 vector was also able to infect neuraminidase-treated Chang C cells. Thus, subgroup D adenoviral binding to the 50-kDa protein is calcium-dependent and cell type- and serotype-specific, whereas binding to the 60-kDa protein is not necessary for infection of conjunctival cells. Together, these data suggest that the 50-kDa protein is the major receptor for Ad37 on conjunctival cells.     

Interleukin-2-dependent control of disease development in spontaneously diabetic BB rats.

Long-term treatment with recombinant interleukin-2 (IL-2) of diabetes-prone BB rats had contrasting effects in two different BB rat sublines. Diabetes development was enhanced in the subline with a low intrinsic diabetes risk and suppressed in the subline with a high diabetes risk. IL-2 treatment started between 35 and 42 days of age and lasted for 3 months. In subline 1, diabetes incidence increased from 23% to 53% (P less than 0.01), in subline 2 it decreased from 73% to 32% (P less than 0.01). The two sublines differed in serum levels of factors controlling IL-2 synthesis and activity. Mean IL-2 inhibitory activity was higher in subline 2 (between 140% and 290% of levels in subline 1, P less than 0.01). Conversely, mean concentrations of thymosin alpha 1 and beta 4 were higher in subline 1 (between 140% and 200% of levels in subline 2, P less than 0.01). Thus the two sublines differ in their response to exogenous IL-2 and also in serum levels of mediators affecting availability of IL-2. We conclude that an internal network of hormonal factors, including IL-2, contributes to the control of diabetes development in the BB rat.     

Mouse homologues of the human AZF candidate gene RBM are expressed in spermatogonia and spermatids, and map to a Y chromosome deletion interval associated with a high incidence of sperm abnormalities

An RNA-binding motif (RBM) gene family has been identified on the human Y chromosome that maps to the same deletion interval as the 'azoospermia factor' (AZF). We have identified the homologous gene family (Rbm) on the mouse Y with a view to investigating the proposal that this gene family plays a role in spermatogenesis. At least 25 and probably >50 copies of Rbm are present on the mouse Y chromosome short arm located between Sry and the centromere. As in the human, a role in spermatogenesis is indicated by a germ cell-specific pattern of expression in the testis, but there are distinct differences in the pattern of expression between the two species. Mice carrying the deletion Yd1, that maps to the proximal Y short arm, are female due to a position effect resulting in non-expression of Sry ; sex-reversing such mice with an Sry transgene produces males with a high incidence of abnormal sperm, making this the third deletion interval on the mouse Y that affects some aspect of spermatogenesis. Most of the copies of Rbm map to this deletion interval, and the Yd1males have markedly reduced Rbm expression, suggesting that RBM deficiency may be responsible for, or contribute to, the abnormal sperm development. In man, deletion of the functional copies of RBM is associated with meiotic arrest rather than sperm anomalies; however, the different effects of deletion are consistent with the differences in expression between the two species.      

Auditory Discrimination and the Eyeblink

This experiment evaluated the association between blinking and cognitive activities. Subjects received 200 and 400 ms tones (1 KHz) at fixed intervals in a duration discrimination paradigm. One group (“Task”) was instructed to respond to the stimuli on the basis of duration and another (“No-Task”) was instructed to ignore the stimuli. Blink activity (latency, rate, duration) and performance (RT, hit and false alarm rates) measures were evaluated. A first analysis (Task subjects only) indicated that stimulus duration had significant effects on RT and blink latency; both were generally longer following the 400-ms than the 200-ms stimuli. In a second analysis, involving Task and No-Task subjects, blink latencies were shorter in the Task group. Blink and eyelid closure durations increased over the task period in both analyses. These effects suggest that blinks occur when attentional processes wane.     

Prevalence of Eikenella corrodens in dental plaque.

The prevalence of Eikenella corrodens in dental plaque and saliva samples of 282 volunteers was determined by a semiquantitative method with a selective medium. E. corrodens was recovered in 58.9% of plaque samples and 0.3% of saliva samples. This prevalence rate was not significantly altered (P greater than 0.05) by variables of sex, race, smoking habits, clinic attended by the patient, general health status, or age; however, patients 7 to 14 years old had a significantly higher prevalence rate (90.5%; P less than 0.05). E. corrodens should be considered as a potential pathogen in infections associated with and wounds inoculated by the human gingival flora.     

Two-colour immunofluorescence studies on EBV-determined antigens

Two-colour fluorescence (TRITC and FITC) has been adapted for the direct visualization of Epstein-Barr virus (EBV)-determined membrane antigens (MA) and to study their relationship to genetically determined iso-antigens (HL-A type) and to viral capsid antigens (VCA, as defined by the Henle test). The following three postulates, based on indirect deductions from previous blocking, cross-blocking and absorption experiments, could be confirmed by direct visual observation:

(1) Membrane receptors of the HL-A and of the EBV determined MA type are distinct with regard to localization and antigenic specificity;

(2) Different subcomponents within the MA complex are part of the same macromolecular structure on the outer cell membrane;

(3) VCA and MA antigens are distinct with regard to specificity.

In addition, it has been shown that all VCA positive cells are also MA positive in EBV-carrier cultures, but that there exists, in such cultures, a 10-fold excess of MA positive, VCA negative cells.