Hepatitis E seroconversion in United States travelers abroad.

Sporadic cases of symptomatic hepatitis E virus (HEV) infection have been reported in United States travelers to developing countries, including Mexico and Pakistan. To evaluate the risk of exposure in United States travelers, 356 patients seen in our Travel Clinics were tested for antibodies to HEV before and 6 weeks after traveling. Samples obtained 6 months after traveling were available for 211 travelers. IgG and IgM antibodies to HEV were assayed with HEV ELISA diagnostic kits containing 3 recombinant antigens expressed in Escherichia coli representing immunodominant epitopes within open reading frames 2 and 3 of HEV. Nine patients were IgG seropositive in specimens obtained before travel. Four individuals seroconverted. In all 4 patients, IgG seroconversion was demonstrated in samples obtained at least 6 months after return. Samples obtained 6 weeks after return were seronegative for HEV in all 3 patients for whom such samples were available. Travel destinations were diverse: Thailand, China, Russia, and Peru. These data are consistent with an infection acquired while traveling. None of the seropositive subjects reported any symptoms of hepatitis before or after travel. In the absence of overt disease, these results imply that exposure to HEV resulted in subclinical infections.

The effects of heparin on the activated partial thromboplastin time of the College of American Pathologists Survey specimens. Responsiveness, precision, and sample effects.

Heparinized survey samples from the College of American Pathologists from 1981 through 1984 were reviewed to assess effects of the various reagents and instrumentation on the performance of the activated partial thromboplastin time (aPTT) in response to heparin. Responsiveness of the aPTT to the concentration of heparin as well as its sensitivity to the detection of heparin in the therapeutic range was most affected by choice of reagents. Precision was most affected by choice of instruments with photo-optical devices being roughly comparable. A previously described effect of calcium vs sodium salts of heparin was not supported by these data. Survey results were compared with results from fresh plasma samples from patients who had received heparin therapeutically and with response curves obtained from specimens heparinized ex vivo. The pattern of reagent dose responsiveness to the heparinized patient samples differed from that seen with survey samples and with the ex vivo heparinized fresh plasma samples. In addition, intrinsic characteristics of the individual specimens exerted substantial effects on the test results for all specimen types. Therefore, one cannot automatically assume that phenomena that hold for one form of plasma preparation are applicable to another. The nature and source of the heparinized plasma specimen must be taken into account when interpreting aPTT results.

Xid and normal mice express a light chain-associated cross-reactive idiotype in response to (T,G)-A--L and (T,G)-A--L-mBSA.

Rabbit anti-idiotypic (Id) antibodies were prepared against purified ascites anti-(T,G)-A--L antibodies (TGB5) that had been absorbed to remove A--L-specific antibodies and were specific for (T,G)-side chain determinants. Purified rabbit anti-TGB5 Id antibodies detected an allotype-independent, light chain-associated cross-reactive Id expressed by the majority of individual mice immunized with (T,G)-A--L, (T,G)-A--L coupled to methylated bovine serum albumin (mBSA), or the linear terpolymer GAT. Primary and secondary monoclonal hybridoma protein (HP) antibodies from X/Xxid heterozygous (wild-type) mice immunized with (T,G)-A--L and/or (T,G)-A--L-mBSA were analyzed for isotypy and were grouped into eight antibody fine specificity sets defined by the patterns of direct binding to the antigens (T,G)-A--L, (Phe,G)-A--L, (T,G)-Pro--L, GT, and A--L. Analysis of these primary and secondary HP for TGB5 idiotypy showed a preferential expression of the TGB5 Id among GT+-binding HP (antibody fine specificity sets 1 through 3). All of the primary GT+-binding HP and the majority of secondary GT+-binding HP (sets 1 through 3) were TGB5 Id+. Most but not all of the TGB5 Id+ HP bound GAT. Of the side-chain-specific HP (sets 1 through 7), 78% of primary HP vs 49% of secondary HP bound GT. By these criteria, the primary HP response appears more restricted than the secondary HP response, consistent with the idea that Id diversification and antibody heterogeneity are regulated and selected events occurring during memory B cell generation. Although xid mice produce less antibody than wild-type mice to (T,G)-A--L, the TGB5 Id was produced early in the primary response by both xid and wild-type mice immunized with (T,G)-A--L or (T,G)-A--L-mBSA, and was maintained as a detectable Id in equivalent amounts in their secondary serum antibody responses. These results support the idea that distinct B cell subsets, including the xid B cell subset, share the same immunoglobulin gene repertoire.

Aortic valvular tophus: identification by X-ray diffraction of urate and calcium phosphates.

A typical gouty tophus with birefringent, dichroic, needle shaped crystals was found in a resected calcified aortic valve on routine histological examination. The patient, an elderly man, had a long history of gout. X-ray diffraction confirmed the presence of sodium acid urate monohydrate and identified hydroxyapatite and whitlockite in the accompanying dystrophic calcification of the aortic valves. Previous reports indicate that gouty tophi of the cardiac valves are rare: of the nine cases reported, eight occurred in the mitral valve.