Detection of human immunodeficiency virus type 1 p24 antigen and plasma RNA: relevance to indeterminate serologic tests

BACKGROUND

Most enzyme immunoassay-reactive specimens producing indeterminate Western blot results belong to individuals who are not infected with human immunodeficiency virus type 1 (HIV-1). However, a small percentage may correspond to early seroconversion or advanced disease, at which stage partial reactivity on Western blot may be observed.

STUDY DESIGN AND METHODS

To determine the utility of HIV-1 p24 antigen and cell-free RNA detection for the resolution of Western blot-indeterminate serologic results, several types of enzyme immunoassay-positive, sero-indeterminate specimens were analyzed. Samples were obtained from infected individuals at the time of seroconversion (n = 20), from patients with AIDS (n = 2), as specimens from clinical samples obtained for diagnostic testing (n = 57), from blood donors producing persistent indeterminate results (n = 47), and from random blood donors (n = 72).

RESULTS

HIV-1 p24 antigen was detected in 10 of 20 specimens collected from 9 of 12 individuals who seroconverted and in 2 of 2 AIDS patients. HIV-1 plasma RNA was positive in 22 of 22 samples from those 14 individuals. All of 57 diagnostic specimens and 47 samples obtained from persistently indeterminate donors were negative for HIV-1 p24 antigen and plasma HIV-1 RNA. One of 72 blood donor specimens was positive for HIV-1 plasma RNA and had borderline reactivity for p24 antigen.

CONCLUSION

The detection of plasma RNA appears to be sensitive and specific; negative test results may be used to identify false-positive serologic reactions. The detection of p24 antigen and plasma RNA can also be used to confirm HIV-1 infection in persons with indeterminate serologic results associated with early seroconversion or late-stage disease.

Human T-lymphotropic virus type II in Panamanian Guaymi Indians

BACKGROUND

Currently, human T-lymphotropic virus type II (HTLV-II) is the most prevalent human retrovirus, detected in persons presenting to donate blood in the United States. Only scant information is available with which to counsel HTLV-II-seropositive deferred donors or other persons about the ways in which they may spread HTLV-II to others.

STUDY DESIGN AND METHODS

To increase understanding of the modes of transmission of HTLV-II, a seroepidemiologic study was conducted among Panamanian Guaymi Indians, a recently identified focus of endemic HTLV-II infection. Subjects were tested for serologic evidence of infection by HTLV-II, HTLV type I, hepatitis B virus, and nine other infectious agents by enzyme immunoassays and specific confirmatory tests.

RESULTS

Nine (8.3%) of 109 persons tested HTLV-II-seropositive. HTLV-II seropositivity was more likely in persons with serologic evidence of prior hepatitis B virus infection. Sexual contact with HTLV-II-seropositive partners, but neither parenteral exposure nor breast-feeding, was identified as a risk factor for HTLV-II.

CONCLUSION

In Guaymi Indians, HTLV-II appears to be spread primarily through sexual transmission.

Identification of rifampin-inducible P450IIIA4 (CYP3A4) in human small bowel enterocytes

Enzymes within the P450IIIA (CYP3A) subfamily appear to account for significant "first pass" metabolism of some drugs in the intestine. To identify which of the known P450IIIA genes are expressed in intestine, enterocyte RNA was hybridized on Northern blots with synthetic oligonucleotides complementary to hypervariable regions of hepatic P450IIIA4, P450IIIA5, and P450IIIA7 cDNAs. Hybridization was detected only with the P450IIIA4-specific oligonucleotide. The identity of the hybridizing mRNA was confirmed to be P450IIIA4 by direct sequencing of a DNA fragment amplified from enterocyte cDNA by the polymerase chain reaction. To determine if enterocyte P450IIIA4 is inducible, biopsies of small bowel mucosa were obtained from five volunteers before and after they received 7d of treatment with rifampin, a known inducer of P450IIIA4 in liver. Rifampin treatment resulted in a five- or eightfold mean increase (P < 0.05) in the biopsy concentration of P450IIIA4 mRNA when normalized for content of sucrase isomaltase or intestinal fatty acid binding protein mRNAs, respectively. Rifampin also induced P450IIIA immunoreactive protein in enterocytes in each of the subjects, as judged by immunohistochemistry, and resulted in a 10-fold increase in P450IIIA4-specific catalytic activity (erythromycin N-demethylation) in the one patient studied. Our identification of inducible P450IIIA4 in enterocytes may in part account for drug interactions characteristic of P450IIIA4 substrates and suggests a strategy for controlling entry into the body of a major class of xenobiotics.

Characterization of a novel receptor in toad retina with dual specificity for insulin and insulin-like growth factor I

The biochemical properties of insulin receptors from toad retinal membranes were examined in an effort to gain insight into the role this receptor plays in the retina. Competition binding assays revealed that toad retinal membranes contained binding sites that displayed an equal affinity for insulin and insulin-like growth factor I (IGF-I). Affinity labeling of toad retinal membrane proteins with 125I-insulin resulted in the specific labeling of insulin receptor alpha-subunits of approximately 105 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of partially reduced (alpha beta-heterodimer) receptors affinity-labeled with 125I-insulin indicated the presence of a disulfide-linked beta-subunit of approximately 95 kDa. Endoglycosidase F digestion of the affinity-labeled alpha-subunits increased their mobility by reducing their apparent mass to approximately 83 kDa. This receptor was not detected by immunoblot analysis with a site-specific antipeptide antibody directed against residues 657-670 of the carboxy terminal of the human insulin receptor alpha-subunit, whereas this antibody did label insulin receptor alpha-subunits from pig, cow, rabbit, and chick retinas. In in vitro autophosphorylation assays insulin stimulated the tyrosine phosphorylation of toad retina insulin receptor beta-subunits. These data indicate that toad retinal insulin receptors have a heterotetrameric structure whose alpha-subunits are smaller than other previously reported neuronal insulin receptors. They further suggest that a single receptor may account for both the insulin and IGF-I binding activities associated with toad retinal membranes.

Retroviral infections transmitted by blood transfusion

Modifications in donor screening and the introduction of laboratory testing of donated blood for anti-HIV-1 and anti-HTLV-I have resulted in a significant reduction in the risks of retroviral infections from blood transfusion. Presently, the American Red Cross detects an average of eight carriers of human immunodeficiency virus, type 1 (HIV-1) per 100,000 otherwise acceptable blood donors (0.008 percent), compared with an average of 35 per 100,000 (0.035 percent) when testing for HIV-1 antibodies began in 1985. Surveillance studies in the United States indicate a small likelihood that HIV-2 carriers will pass current screening procedures and be accepted as blood donors. Even if an HIV-2-infected person were to be accepted as a blood donor, there is a 42-92 percent likelihood that this person's blood would be detected as infective for HIV-2 and excluded because of serological cross-reactions that occur in the EIA for HIV-1 antibodies. During 1989, which was the first year that donated blood was routinely tested for antibodies to human T-lymphotropic virus, type I (HTLV-I) in the United States, approximately nine in 100,000 donors (0.009 percent) were confirmed positive for antibodies to HTLV-I, and their donated blood was excluded. Subsequent testing has revealed that a significant number of these persons whose sera was reactive by the HTLV-I EIA were, in fact, infected by HTLV-II. Epidemiological studies of human retroviral infections (HIV-1, HIV-2, HTLV-I, and HTLV-II) continue to provide important data and direction for improving criteria for qualifying blood donors.

[Immunochemical identification and localization of cytochrome P-45OHS; isozyme in human gastric mucosa and gastric carcinoma]

Monoclonal antibody to rat liver cytochrome P-450 j isozyme, an activating enzyme specific to nitrosamine metabolism, was used in combination with immunoblotting, densitometer scanning of SDS-PAGE gels, and immunohistochemical staining, there was a trace of P-450 isozyme (Mr. 51. 5 kd) in human gastric mucosa with or without cancer. It was similar to P-450 j in molecular weight, catalysis and immunochemistry. We named it P-450 HSj isozyme. Both in 25 gastric cancer patients and 17 non-cancer patients, the concentrations (%) of P-450 HSj in the mucosa of the lesser curvature were higher than those of the greater curvature (P less than 0.01). This might be one of the important reasons why gastric carcinoma caused by nitrosamines is most common in the lesser curvature. The P-450 HSj was localized in the cytoplasm of some epithelial cells, especially in the glands with hyperplastic and intestinal metaplastic changes adjacent to carcinoma. It was also found in some normal glands and in tumor cells of highly differentiated adenocarcinoma, but not in tumor cells of lowly differentiated adenocarcinoma.

A test for human cytomegalovirus-specific immunoglobulins using a modification of a commercial test kit

A technique (Ig-EIA) for the detection of CMV-specific IgG, IgM and IgA in human blood is described. Ig-EIA utilizes alkaline phosphatase-labeled goat anti-human IgG, IgM and IgA as a detection probe and CMV antigen-coated solid phase from commercial kits. Ig-EIA is compared to indirect fluorescent assay (IFA) and indirect hemagglutination (IHA) for sensitivity and specificity. On sequential samples of blood from a set of patients, Ig-EIA clearly demonstrated seroconversion in CMV-specific IgG and IgM. A test of 332 blood donors by Ig-EIA showed 177 (53%) had CMV-specific IgG and 17 (5%) had CMV IgM. Only two of the 17 donors with CMV IgM were nonreactive for CMV-IgG. The potential of CMV-IgM as an indicator of CMV infectivity is discussed.

Failure of topical prostaglandin inhibitors to improve wound healing following deep partial-thickness burns

The present study was designed to determine the efficacy of topical inhibitors of prostaglandins on wound healing. Two uniform deep partial-thickness burns were inflicted on mirror-image areas of guinea pig backs by an aluminum template heated to 75 degrees C and applied for 10 seconds. Indomethacin was tested extensively in a wide range of concentrations in groups of six or more animals each. The healing rates measured at 21 days postburn showed that topical indomethacin at each concentration tested was not effective for improving wound healing. In fact, the treated sites were consistently worse than the control sites. Moreover, the drug adversely affected the healing process proportional to the concentration and was associated with death, which was related to perforations of the GI tract. Also, the India ink filling in the dermal microcirculation was no better in the experimental wounds than in the controls. The evaluations for hair growth were definitely in favor of the controls. The other tested inhibitors, ibuprofen, flurbiprofen, tolmetin, zomepirac, piroxicam, and dipyridamole, also failed to show any benefit.

Morphogenesis of vaccinia virus in the process of envelopment as observed by freeze-etching electron microscopy

The morphogenesis of vaccinia virus was studied during its synthesis in HeLa cells. Freeze-etching electron microscopy demonstrated intramembrane granules attached to convex faces, a granule-free area characterized by eccentric location and smooth appearance, and an eccentric nucleoid structure occasionally associated with a membranous structure. It is postulated that the granule-free area may be a precursor of the nucleoid envelope.

Preliminary study on the age of Yuanmou man by palaeomagnetic technique

Since the discovery of the fossil teeth of Yuanmou man (Homo erectus yuanmouensis) on May 1, 1965 from Yuanmou county, Yunnan Province, the Institute of Geomechanics, relying on the local poor and lower-middle peasants and co-operating with other units concerned, has been conducting intensive researches on the fossil man-bearing strata as well as Quaternary glaciation. Palaeomagnetic technique lately used in the study has for the first time shown that the Yuanmou man appeared around 1.7 million years ago, earlier than both Peking man and Lantien man. Hence the age formerly assigned to the earliest fossil man in China has to be increased by more than a million years. Furthermore, as the age of Yuanmou formation is fixed at 1.5--3.1 million years, the length of Quaternary has to be extended by more than two million years. Of special interest is that under the Yuanmou formation there occur glacial traces which prove beyond doubt the existence of glaciation over 3 million years ago. This is a new discovery in the Quaternary history of China, and provides a new approach to the future study of this period.