Metallothionein as a clonable tag for protein localization by electron microscopy of cells

A benign, clonable tag for the localization of proteins by electron microscopy of cells would be valuable, especially if it provided labelling with high signal-to-noise ratio and good spatial resolution. Here we explore the use of metallothionein as such a localization marker. We have achieved good success with desmin labelled in vitro and with a component of the yeast spindle pole body labelled in cells. Heavy metals added after fixation and embedding or during the process of freeze-substitution fixation provide readily visible signals with no concern that the heavy atoms are affecting the behaviour of the protein in its physiological environment. However, our methods did not work with protein components of the nuclear pore complex, suggesting that this approach is not yet universally applicable. We provide a full description of our optimal labelling conditions and other conditions tried, hoping that our work will allow others to label their own proteins of interest and/or improve on the methods we have defined.

Effect of vaccine delivery system on the induction of HPV16L1-specific humoral and cell-mediated immune responses in immunized rhesus macaques

There have been numerous studies to assess the immunogenicity of candidate therapeutic and prophylactic vaccines for human papillomavirus (HPV), but few of them have directly compared different vaccines in an immunologically relevant animal system. In the present study, several vaccine delivery systems (VLPs, chimeric VLPs, plasmid DNA, and a replication incompetent adenoviral vector) expressing HPV16L1 were evaluated for their ability to induce HPV16L1 VLP-specific humoral immune responses, including neutralizing antibodies, and cell-mediated immune responses in rhesus macaques. Monkeys immunized with HPV16L1 VLPs mounted a potent humoral response with strongly neutralizing antibodies and a strong L1-specific Th2 response as measured by IL-4 production by CD4+ T cells. Monkeys immunized with plasmid DNA or an adenoviral vector expressing HPV16L1 showed strong Th1/Tc1 responses as measured by IFN-gamma production by CD4+ and/or CD8+ T cells and potent humoral responses, but only weakly neutralizing antibodies. These data demonstrate that the nature of the immune response against HPV16L1 is dramatically different when it is introduced via different delivery systems. Additionally, these findings support the notion that an HPV16L1 VLP-based vaccine will induce the strongly neutralizing antibodies necessary for effective prophylaxis.

Neutralization of human papillomavirus (HPV) pseudovirions: a novel and efficient approach to detect and characterize HPV neutralizing antibodies

The development of vaccines against human papillomaviruses (HPVs) has long been hampered by the inability to grow HPVs in tissue culture and the lack of an efficient neutralization assay. To date, less than 10% of more than 100 different HPV types can be grown in athymic and "SCID" mouse xenograft systems or raft culture systems. Recently, the in vitro generation of HPV pseudovirions and their use in neutralization assays were demonstrated. The major shortcomings of the current approaches to HPV neutralization are the lack of HPV virions for most types for the xenograft methods and the time-consuming and inefficient generation of infective pseudovirions for the latter methods, which precludes their use in large-scale HPV clinical trials or epidemiological studies. We describe here a novel and efficient approach to generating pseudovirions in which HPV virus-like particles (VLPs) are coupled to the beta-lactamase gene as a reporter. We show that it is not necessary to encapsidate the reporter gene constructs into the pseudovirions. Using sera from human volunteers immunized with HPV-11 VLPs expressed in yeast, we demonstrate that our novel neutralization assay compares favorably with the athymic mouse neutralization assay. Furthermore, our assay was used to define neutralizing monoclonal antibodies to HPV-6, which were previously unknown.

Factors associated with discontinuation of continuous subcutaneous insulin infusion

Fifty-five patients who had been started on continuous subcutaneous insulin infusion (CSII) more than 1 year previously were surveyed to determine the difference between those who had continued and those who had discontinued CSII. These retrospective results were used to determine characteristics that predict a suitable candidate for CSII which could be tested in a future prospective study and would guide our clinical choice of candidates for CSII. Twenty patients had discontinued CSII (Group D) and 35 patients had continued CSII (Group C). Group D contained younger patients, more likely to be women who had had a shorter duration of diabetes, more frequent antecedent episodes of diabetic ketoacidosis (DKA), and more frequent doctor visits. The major rationale for starting CSII in Group D was poor control with keotacidosis whereas Group C started CSII for poor control with hypoglycemia. The reasons for stopping CSII in Group D were interference with lifestyle (40%), needle site abcesses (40%), psychological rejection (10%), and poor insulin absorption (10%). Group D patients had a significantly higher incidence of psychological rejection of CSII, dermatological problems, and needle site abcesses. For patients in Group D, glycosylated hemoglobin levels during CSII were similar to those prior to CSII. Group C patients had improved glycosylated hemoglobin levels and were more satisfied with CSII despite a slightly higher incidence of pump runaway. Group C patients had a trend toward more frequent hypoglycemia while on CSII; however, in patients who had reported severe hypoglycemia before starting CSII, there was a significant decline in the frequency of severe hypoglycemia.(ABSTRACT TRUNCATED AT 250 WORDS)