Biomedical subjects

N Salzman

Publications and source records attributed to N Salzman.

5 recordsLinked to original sources

PubMed1996

Human enteric defensins. Gene structure and developmental expression.

Paneth cells, secretory epithelial cells of the small intestinal crypts, are proposed to contribute to local host defense. Both mouse and human Paneth cells express a collection of antimicrobial proteins, including members of a family of antimicrobial peptides named defensins. In this study, data from an anchored polymerase chain reaction (PCR) strategy suggest that only two defensin mRNA isoforms are expressed in the human small intestine, far fewer than the number expressed in the mouse. The two isoforms detected by this PCR approach were human defensin family members, HD-5 and HD-6. The gene encoding HD-6 was cloned and characterized. HD-6 has a genomic organization similar to HD-5, and the two genes have a striking pattern of sequence similarity localized chiefly in their proximal 5'-flanking regions. Analysis of human fetal RNA by reverse transcriptase-PCR detected enteric defensin HD-5 mRNA at 13.5 weeks of gestation in the small intestine and the colon, but by 17 weeks HD-5 was restricted to the small intestine. HD-6 mRNA was detectable at 13.5-17 weeks of gestation in the small intestine but not in the colon. This pattern of expression coincides with the previously described appearance of Paneth cells as determined by ultrastructural approaches. Northern analysis of total RNA from small intestine revealed quantifiable enteric defensin mRNA in five samples from 19 24 weeks of gestation at levels approximately 40-250-fold less than those observed in the adult, with HD-5 mRNA levels greater than those of HD-6 in all samples. In situ hybridization analysis localized expression of enteric defensin mRNA to Paneth cells at 24 weeks of gestation, as is seen in the newborn term infant and the adult. Consistent with earlier morphological studies, the ratio of Paneth cell number per crypt was reduced in samples at 24 weeks of gestation compared with the adult, and this lower cell number partially accounts for the lower defensin mRNA levels as determined by Northern analysis. Low levels of enteric defensin expression in the fetus may be characteristic of an immaturity of local defense, which is thought to predispose infants born prematurely to infection from intestinal microorganisms.

Amino Acid Sequence↗

PubMed1993

Induction of humoral and cell-mediated anti-human immunodeficiency virus (HIV) responses in HIV sero-negative volunteers by immunization with recombinant gp160.

Development of an effective vaccine for prevention of infection with HIV would provide an important mechanism for controlling the AIDS epidemic. In the current study, the first clinical trial of a candidate HIV-1 vaccine initiated in the United States, the safety and immunogenicity of escalating doses (10-1,280 micrograms) of recombinant gp160 (rgp160), were evaluated in 138 HIV-negative volunteers. Maximal antibody responses, as evaluated by ELISA, were seen after immunization with three doses of 1,280 micrograms rgp160. Responses to some specific epitopes of HIV gp160, including the second conserved domain and the CD4 binding site, were seen more frequently than after natural infection. Neutralizing antibodies to the homologous HIV strain, but not heterologous strains, were induced by this regimen. Blastogenic responses to rgp160 were seen in most volunteers receiving at least two doses of > or = 20 micrograms. These envelope-specific T cell responses were also seen against heterologous strains of HIV. No major adverse reactions were seen after immunization. Thus, rgp160 is a safe and immunogenic candidate HIV vaccine; further studies are needed to determine if it will provide any clinical benefit in preventing HIV infection.

AIDS Vaccines↗

PubMed1988

Anti-retroviral effects of interferon-alpha in AIDS-associated Kaposi's sarcoma.

21 patients with AIDS and Kaposi's sarcoma were enrolled in an open therapeutic trial to determine the in vivo anti-retroviral activity of recombinant interferon-alpha (IFN-alpha). 8 (38%) showed a complete or partial anti-tumour response. The mean pretreatment CD4 count for the responders was 399 cells/microliter vs 154 cells/microliter for the non-responders. All 5 of the patients with more than 400 CD4 cells/microliter pretreatment showed a significant reduction in tumour, whereas none of the 7 patients with under 150 CD4 cells/microliter had any response. 5 of the 6 complete or partial responders with greater than 50 pg/ml of human immunodeficiency virus (HIV) p24 before IFN therapy showed a 75% or greater reduction by 12 weeks of therapy, with 3 patients having persistently negative HIV cultures. The anti-viral effects were also most pronounced in the patients with the highest CD4 counts. These data demonstrate the potential benefits, both anti-tumour and anti-retroviral, of treatment with IFN-alpha in the early stages of HIV infection and Kaposi's sarcoma.

Acquired Immunodeficiency Syndrome↗

PubMed1984

Stimulation of simian virus 40 late gene expression by simian virus 40 tumor antigen.

The early simian virus 40 (SV40) gene product, large tumor (T) antigen, is responsible for the initiation of viral DNA replication and the autoregulation of early gene expression through direct protein-DNA interactions. We investigated the role of T antigen in late viral gene expression, independent of its function in amplifying templates through DNA replication. SV40 DNA was transfected into BSC-1 and COS-1 cells and cultured in the presence of inhibitors of DNA replication. Electrophoretic immunoblot analysis indicated that both the onset and the extent of SV40 late gene expression is increased in COS-1 cells, which constitutively express SV40 T antigen. Blot hybridization analysis of poly(A)-selected RNA demonstrated that the level of synthesis of the major late structural protein VP-1 in COS-1 cells was due to increased transcription. Similar results were obtained when plasmids that contain the SV40 late gene but lack both the origin for viral DNA replication and the early gene coding region were transfected onto COS-1 cells. Using lines of SV40-transformed monkey kidney cells that express altered T antigens, we found that enhanced expression of the late gene product is correlated with the ability of T antigen to bind SV40 DNA. These results indicate that large T antigen plays a role in the stimulation of late viral gene expression.

Animals↗

PubMed1979

Rapid sequence determination of late simian virus 40 16S mRNA leader by using inhibitors of reverse transcriptase.

A method for the determination of the primary structure of spliced mRNA junction and leader sequences is described. By analogy to the DNA sequencing procedure of Sanger et al. [Sanger, F., Nicklen, S. & Coulson, A. R. (1977) Proc. Natl. Acad. Sci USA 74, 5463--5467], we use 2",3'-dideoxynucleoside triphosphates as chain-terminating inhibitors of the reverse transcriptase (RNA-dependent DNA polymerase) reaction. By using specific DNA restriction fragments as primers in combination with this technique, we have determined the sequence of the spliced junction between the body and the leader sequence of the 16S late mRNA of simian virus 40. The method described should be of general utility in mapping spliced mRNA regions for which the corresponding protein sequence (if any) is unknown.

Base Sequence↗