Negative regulation of human immune deficiency virus replication in monocytes. Distinctions between restricted and latent expression in THP-1 cells.

In THP-1 monocytoid cells infected with HIV, viral expression can be regulated in several ways: (a) latency (no viral expression); (b) restricted expression (chronic low-level viral expression with little or no detectable virus released); and (c) continuous production. In cells with restricted HIV expression, nuclear factor(s) were found that blocked tat-associated DNA binding complex formation, suggesting that initiation of transcription was negatively regulated. Also, viral particles were seen budding into and accumulating within intracytoplasmic vacuoles with little virus released, suggesting multiple levels of regulation. These cells with restricted expression had no detectable viral antigens on the cell surface and were not lysed by IL-2-activated large granular lymphocytes. However, they could cause viral-mediated T cell cytolysis in cell-cell assays, suggesting viral transmission through cell contact. In addition, cells with latent HIV were identified and could still produce infectious virus after 5-azacytidine exposure 10 mo later. LPS and other treatments could increase viral production in cells with restricted but not latent expression, suggesting they occur by distinct mechanisms. These infected cells provide a reservoir for viral transmission to uninfected T cells that itself is not detected by immune surveillance mechanisms.

Monozygotic twin formation in mouse embryos in vitro.

Monozygotic twins developed from cultured murine blastocysts at the ratio of approximately 1:100. The locus at which the denuded blastocysts attached to the culture dish was usually a random section of their mural trophoblasts, in which case single egg cylinders developed unilaterally. However, in those few blastocysts attaching with their antipolar mural trophoblasts, the inner cell mass became subdivided into two parts because of restrictions imposed on its growth by the apically situated polar trophoblasts and the plastic substrate. Each subdivision apparently incorporated totipotent cells, resulting in the bilateral formation of two egg cylinders sharing the same ectoplacental cone.

Sequence homology and morphologic similarity of HTLV-III and visna virus, a pathogenic lentivirus.

A study was conducted of the genetic relation between human T-cell lymphotropic retroviruses and visna virus. The human T-cell lymphotropic viruses include those associated with T-cell malignancies (HTLV-I and HTLV-II) as well as the etiologic agent of the acquired immune deficiency syndrome (HTLV-III). Visna virus, a slowly replicating and pathogenic but nononcogenic retrovirus of sheep, is a member of the subfamily Lentivirinae. Results obtained by molecular hybridization and heteroduplex analysis indicated that a greater extent of nucleotide sequence homology exists between HTLV-III and visna virus than between HTLV-III and any of the other viruses. The homology observed under conditions of low stringency spanned the entire genome, but was strongest in the gag/pol region. The morphogenesis and fine structure of HTLV-III and visna virus also demonstrated striking similarities. The data provide strong evidence for a close taxonomic and thus evolutionary relation between HTLV-III and the Lentivirinae subfamily.

Characterization of envelope and core structural gene products of HTLV-III with sera from AIDS patients.

The envelope (env) and structural (gag) gene products of human T-cell leukemia (lymphotropic) virus type III were identified by immunoaffinity chromatography, immunoprecipitation, and two-dimensional oligopeptide mapping methods. The env gene specifies a glycosylated polypeptide with a molecular weight of 160,000 (gp160) that is processed to gp120 and smaller gene products. The gag gene specifies two polypeptides of 70,000 and 55,000 molecular weight (p70 and p55), both of which contain p24, the major structural protein of the mature virion. The techniques in this study can be used to define the extent of variability of the env gene product among different virus isolates and may identify the nature and patterns of the humoral immune response that lead to an immunologically protected state.

HTLV-III in saliva of people with AIDS-related complex and healthy homosexual men at risk for AIDS.

Peripheral blood leukocytes and saliva from 20 individuals, including four with the acquired immune deficiency syndrome (AIDS), ten with AIDS-related complex (ARC), and six healthy homosexual males at risk for AIDS, were compared as sources of transmissible human T-cell leukemia (lymphotropic) virus type III (HTLV-III), the virus found to be the etiologic agent of AIDS. All of the AIDS and ARC patients and four of the six healthy homosexuals had evidence of prior exposure to HTLV-III as indicated by seropositivity for antibody to HTLV-III structural proteins. Infectious virus was isolated from the peripheral blood of one of the AIDS patients, four of the ARC patients, and two of the healthy homosexual males, consistent with previous reports. HTLV-III was also isolated from the saliva of four of the ARC patients and four of the healthy homosexuals. Virus was also observed by electron microscopy in material prepared by centrifugation of the saliva of one AIDS patient. Although AIDS does not appear to be transmitted by casual contact, the possibility that HTLV-III can be transmitted by saliva should be considered.

Serological analysis of a subgroup of human T-lymphotropic retroviruses (HTLV-III) associated with AIDS.

The two main subgroups of the family of human T-lymphotropic retroviruses (HTLV) that have previously been characterized are known as HTLV-I and HTLV-II. Both are associated with certain human leukemias and lymphomas. Cell surface antigens (p61 and p65) encoded by HTLV-I are frequently recognized, at low titers, by antibodies in the serum of patients with acquired immunodeficiency syndrome (AIDS) or with signs or symptoms that precede AIDS (pre-AIDS). This suggests an involvement of HTLV in these disorders. Another subgroup of HTLV, designated HTLV-III, has now been isolated from many patients with AIDS and pre-AIDS. In the studies described in this report, virus-associated antigens in T-cell clones permanently producing HTLV-III were subjected to biochemical and immunological analyses. Antigens of HTLV-III, specifically detected by antibodies in serum from AIDS or pre-AIDS patients and revealed by the Western blot technique, are similar in size to those found in other subgroups of HTLV. They include at least three serologically unrelated antigenic groups, one of which is associated with group-specific antigens (p55 and P24) and another with envelope-related (p65) proteins, while the antigens in the third group are of unknown affiliation. The data show that HTLV-III is clearly distinguishable from HTLV-I and HTLV-II but is also significantly related to both viruses. HTLV-III is thus a true member of the HTLV family.

HTLV-III in the semen and blood of a healthy homosexual man.

Human T-lymphotropic virus type III (HTLV-III) is the probable etiologic agent for the acquired immune deficiency syndrome (AIDS). HTLV-III was isolated from semen and blood of a healthy homosexual man whose serum contains antibodies to HTLV-III. The finding of virus in semen supports epidemiologic data that suggest that AIDS can be transmitted sexually. In addition, the demonstration of HTLV-III in the blood and semen of a healthy individual establishes an asymptomatic, virus-positive carrier state which may be important in the dissemination of HTLV-III and, consequently, AIDS.

Effect of Mycobacterium paratuberculosis infection on production, reproduction, and health traits in US Holsteins.

Our objective was to estimate the effect of Mycobacterium paratuberculosis infection on milk, fat, and protein yield deviations, pregnancy rate, lactation somatic cell score, and projected total months in milk (productive life). A serum ELISA and fecal culture for M. paratuberculosis were performed on 4375 Holsteins in 232 DHIA herds throughout the US. Primarily first through third lactation cows (99% of total) were assayed for infection. Trait information (except productive life) was obtained for the lactation concurrent with disease tests. Productive life was total months in milk through a cow's life, which was projected if a cow was still milking. For most analyses, case definition for M. paratuberculosis infection was defined as either an ELISA S/P ratio>or=0.25 or a positive fecal culture for M. paratuberculosis or both. To determine if diagnostic test affected estimates, case definition was redefined to include only cows with ELISA S/P ratios>or=0.25 or only fecal culture-positive cows. Linear models were used to estimate effect of M. paratuberculosis infection on traits. M. paratuberculosis-infected cows (7.89% of cows) produced 303.9 kg less milk/lactation, 11.46 kg less fat/lactation, and 9.49 kg less protein/lactation (P

Genetic variation of Mycobacterium avium ssp. paratuberculosis infection in US Holsteins.

The objective of this study was to estimate genetic variability of Mycobacterium avium ssp. paratuberculosis infection in US Holsteins. Blood and fecal samples were collected primarily from daughters of 12 bulls in their second or third lactation. Routine disease testing of the sires documented that they were not infected. Herds without a "suspect" or positive ELISA (sample/positive ratio > or = 0.10) or positive fecal culture test were deleted from the data set. The remaining 4,603 cows from 238 herds and 46 sires were used to estimate heritability of M. paratuberculosis infection. Heritability was estimated with 3 Johne's disease diagnostic tests: 1) fecal culture alone, 2) serum antibody ELISA alone, and 3) both tests (combined) with a positive animal defined as all animals with either a positive fecal culture or ELISA test. Four statistical models were used to estimate heritability: 1) linear (ELISA), 2) threshold (fecal culture and combined), 3) ordered threshold (ELISA), and 4) bivariate linear-threshold (ELISA-fecal culture). A sire model and Bayesian approach using Markov chain Monte Carlo methods were used in each case. Heritability of infection based on the fecal culture test was 0.153 [posterior standard deviation (PSD) = 0.115]. Heritability with the ELISA was 0.159 (PSD = 0.090) with a linear model and 0.091 (PSD = 0.053) with an ordered threshold model. Heritability of the combined tests was 0.102 (PSD = 0.066). Heritability estimates of fecal culture and ELISA with the bivariate model varied slightly from estimates obtained with the univariate models (0.125 and 0.183, respectively), with a corresponding increase in precision (PSD = 0.096 and 0.082, respectively). This study demonstrates that exploitable genetic variation exists in dairy cattle for M. paratuberculosis infection susceptibility.

Ultrastructural studies of surface features of human normal and tumor cells in tissue culture by scanning and transmission electron microscopy.

Human tumors of a variety of histopathologic types have been established in tissue culture. The surface features of these cell lines were investigated by scanning electron microscopy (SEM) with the use of new techniques for specimen preparation. Tumor cells demonstrated striking degrees of surface activity with numerous microvilli, filopodia, blebs, and ruffles. Intercellular contacts were also prominent in cultures of most solid tumors observed by SEM. At low cell density, normal human fibroblasts exhibited some surface features such as microvilli and blebs, but at higher cell density they lacked extensive surface modifications. By transmission electron microscopy (TEM), the cytoskeleton of normal fibroblasts was shown to be well organized, with parallel orientation of microfilaments, filaments, and microtubules. These structures were also in tumor cells, but they lacked the degree of organization of fibroblasts. Desmosomes were readily demonstrated in normal fibroblasts and carcinoma cells in culture but not in sarcomas, melanomas, or tumors of neural origin. These studies have provided the first correlative SEM and TEM analyses of solid human tumor cells of diverse pathologic types in vitro.

Chronic active hepatitis and associated liver tumors in mice caused by a persistent bacterial infection with a novel Helicobacter species.

BACKGROUND: In the autumn of 1992, a novel form of chronic, active hepatitis of unknown etiology was discovered in mice at the National Cancer Institute-Frederick Cancer Research and Development Center (NCI-FCRDC), Frederick, Md. A high incidence of hepatocellular tumors occurred in affected animals. The disease entity was originally identified in A/JCr mice that were untreated controls in a long-term toxicologic study. PURPOSE: Our original purpose was to determine the origin and etiology of the chronic hepatitis and to quantify its association with hepatocellular tumors in mice of low liver tumor incidence strains. After a helical microorganism was discovered in hepatic parenchyma of diseased mice, we undertook characterization of the organism and investigation of its relationship to the disease process. METHODS: Hepatic histopathology of many strains of mice and rats, as well as guinea pigs and Syrian hamsters, in our research and animal production facilities was reviewed. Steiner's modification of the Warthin-Starry stain and transmission electron microscopy were used to identify bacteria in the liver. We transmitted the hepatitis with liver suspensions from affected mice and by inoculation with bacterial cultures. Bacteria were cultivated on blood agar plates maintained under anaerobic or microaerophilic conditions and characterized morphologically, biochemically, and by 16S rRNA sequence. RESULTS: We report here the isolation of a new species of Helicobacter (provisionally designated Helicobacter hepaticus sp. nov.) that selectively and persistently colonizes the hepatic bile canaliculi of mice (and possibly the intrahepatic biliary system and large bowel), causing a morphologically distinctive pattern of chronic, active hepatitis and associated with a high incidence of hepatocellular neoplasms in infected animals. CONCLUSIONS: The novel Helicobacter is a likely candidate for the etiology of hepatocellular tumors in our mice. The Helicobacter-associated chronic active hepatitis represents a new model to study mechanisms of carcinogenesis by this genus of bacteria. IMPLICATIONS: Adenocarcinoma of the stomach, the second most prevalent of all human malignancies world-wide, is associated with infection at an early age with Helicobacter pylori. Infection leads to several distinctive forms of gastritis, including chronic atrophic gastritis, which is a precursor of adenocarcinoma. H. hepaticus infection in mice constitutes the only other parallel association between a persistent bacterial infection and tumor development known to exist naturally. Study of the H. hepaticus syndrome of chronic active hepatitis and liver tumors in mice may yield insights into the role of H. pylori in human stomach cancer and gastric lymphoma.

Dome formation by a retrovirus-induced lung adenocarcinoma cell line.

A cell line has been established from an alveologenic lung adenocarcinoma that develops in newborn NFS/N mice after i.p. inoculation with a carcinoma-inducing retrovirus. A clonal derivative of this cell line, 3041, forms adenocarcinomas when injected into syngeneic weanling mice and in culture retains several properties typical of alveologenic type 1 cells. These include morphological details, such as tight junctions and interdigitating microvilli in the areas of cell-cell contact, as well as the ability to transport fluid in culture. Fluid transport becomes evident in confluent cultures by the formation of domes or hemicysts. The formation of domes, which is considered to reflect a differentiated function of these secretory epithelial cells, can be enhanced more than 50-fold by treatment with dibutyryl cyclic adenosine 3':5'-monophosphate but only 5- and 3-fold by sodium n-butyrate and dimethyl sulfoxide, respectively. It is anticipated that the secretory alveologenic cell line 3041 described here will be useful for studies of both its pathological and its physiological properties.

Surface localization of virus production on a glucocorticoid-stimulated oncornavirus-producing mouse mammary tumor cell line by scanning electron microscopy.

A chronically infected continuous mouse mammary tumor cell line containing virus particles of type B morphology, free of contaminating type C virions, has been grown in tissue culture. These cells were treated with dexamethasone, a synthetic glucocorticoid, a potent stimulator of mouse mammary tumor virus expression. Surfaces of untreated and dexamethasone-treated cells were investigated by scanning electron microscopy. Untreated cells demonstrated a moderate expression of mouse mammary tumor virus (80 particles/cell) distributed diffusely over the cell surface. However, virions on dexamethasone-treated cells were localized in clusters of 100 to greater than 2000 virus particles, often with more than one cluster per cell. Dexamethasone-treated cells typically showed a 10-fold increase in cell-associated virus over untreated cells. Concentrated extracellular fluids from untreated and dexamethasone-treated cultures were quantitated for free virus. Dexamethasone-treated culture fluids demonstrated a similar 10-fold increase of extracellular particles, in contrast to untreated cultures. This increase in virus particles on the cell surfaces as well as in the extracellular fluids supports the theory that dexamethasone has a stimulatory effect on viral replication, not just on the release of budding particles. The ultrastructure of budding mouse mammary tumor virus during dexamethasone stimulation, determined by scanning and transmission electron microscopy, and the significance of such an in vitro system for viral immunodiagnosis are discussed.

Heteroduplex mapping in the molecular analysis of the human T-cell leukemia (lymphotropic) viruses.

The human T-cell lymphotropic virus (HTLV) family includes members associated with T-cell cancers (HTLV-I and HTLV-II) as well as the etiological agent of the acquired immunodeficiency syndrome (HTLV-III). Molecular clones of these viruses were used in heteroduplex mapping experiments to study their structural and evolutionary relationships. The HTLV-I subgroup, despite some restriction enzyme site polymorphism, demonstrated a high degree of sequence conservation. Heteroduplexes of HTLV-I and HTLV-II demonstrated a significant amount of sequence homology, with the strongest region of conservation occurring in the 3'-most coding sequences, designated pX, and to a lesser, although substantial extent in the rest of the genome. Thus, the genomic organization of HTLV-II appears to be very similar to that of HTLV-I. All HTLV-III molecular clones appeared to be identical, with a single exception, which showed heterogeneity in the env gene region. In heteroduplexes between HTLV-I and HTLV-III, very little homology was observed, being confined to the gap/pol region. In contrast to the latter result, a striking amount of homology was detected between HTLV-III and a morphologically similar, pathogenic, nononcogenic lentivirus, visna virus. These data provide strong evidence for a close taxonomic and thus evolutionary relationship between HTLV-III and the lentivirus subfamily of retroviruses. A taxonomic tree, based on the genetic relatedness and biological properties of the HTLV family, is proposed.

Spontaneous esophageal carcinoma and epithelial cell line of an adult rhesus monkey.

A continuous epithelial cell line, 816A, was established from a lymph node of an adult rhesus monkey with metastatic esophageal carcinoma. These cells are characterized by the presence of desmosomes and a markedly heteroploid karyotype. At a relatively early culture age, electron microscopy showed both budding and extracellular type C virus. Antigen reactive with antisera to Mason-Pfizer monkey virus was observed by complement-fixation. The level of this antigen decreased with increased culture age. To our knowledge, the 816A cells represent the only established simian or human cell line of esophageal carcinoma origin.

The influence of maternal nutrition on expression of genes responsible for adipogenesis and myogenesis in the bovine fetus.

The objective of this study was to determine whether altered maternal energy supply during mid-gestation results in differences in muscle histology or genes regulating fetal adipose and muscle development. In total, 22 Angus cross-bred heifers (BW=527.73±8.3 kg) were assigned randomly to the three dietary treatments providing 146% (HIGH; n=7), 87% (INT; n=7) or 72% (LOW; n=8) of the energy requirements for heifers from day 85 to day 180 of gestation. Fetuses were removed via cesarean section at day 180 of gestation and longissimus muscle (LM) and subcutaneous fat were collected and prepared for analysis of gene expression. Samples from the LM and semitendinosus (ST) were evaluated for muscle fiber diameter, area and number. The right hind limb was dissected and analyzed to determine compositional analysis. Fetal growth and muscle histology characteristics of the LM and ST were similar among treatments. Preadipocyte factor-1 expression was up-regulated in fetal LM (P<0.05) of HIGH fetuses as compared with INT, whereas LOW fetuses showed increased CCAAT/enhancer-binding protein-ß (C/EBP-ß) expression in LM as compared with INT (P<0.05). Peroxisome proliferator-activated receptor γand C/EBP-α did not differ as a result of dietary treatment in LM or subcutaneous fat samples. There was a tendency for increased expression of fatty acid synthase in LM of LOW fetuses as compared with INT (P<0.10). Myogenin was more highly expressed (P<0.05) in LM of the LOW fetuses, whereas µ-calpain expression was increased in the HIGH treatment compared with INT. A tendency for increased expression of IGF-II was observed for both LOW and HIGH fetuses compared with INT (P<0.10). Expression of stearoyl-CoA desaturase, myoblast determination protein 1, myogenic factor 5, myogenic regulatory factor-4, m-calpain, calpastatin, IGF-I and myostatin was similar between treatments. Collectively, these results suggest that fetal growth characteristics are not affected by the level of maternal nutritional manipulation imposed in this study during mid-gestation. However, differences in expression of fetal genes regulating adipose and muscle tissue growth and development could lead to differences in postnatal composition and warrants further investigation.

The influence of maternal energy status during mid-gestation on beef offspring tenderness, muscle characteristics, and gene expression.

The objective of this study was to determine if maternal energy status during mid-gestation influences the expression of genes regulating muscle and fat development, and muscle characteristics that may impact meat tenderness. Cows grazed dormant, native range (Positive Energy Status [PES]) or were fed at 80% of maintenance energy requirements (Negative Energy Status [NES]) during mid-gestation. Steer offspring were harvested after 21 d in the feedlot (weaning subsample) or after 208 d in the feedlot (final subsample). Greater 21-d tenderness was observed in NES steers, resulting from reduced collagen content in longissimus lumborum steaks. In the semitendinosus, NES steers had greater soluble collagen, and down-regulated expression of MHC-IIA and TIMP-3 at weaning, while MHC-IIA expression was up-regulated in NES steers in the final harvest. Data show mid-gestational maternal energy status may impact offspring tenderness and collagen, but differences were not detected in expression of genes important in myogenesis and adipogenesis in muscle samples obtained from steers at weaning or slaughter.

Effect of acute cimetidine administration on indices of parathyroid hormone action in healthy subjects and patients with primary and secondary hyperparathyroidism.

To evaluate the acute effect of histamine H2-receptor blockade with cimetidine on PTH concentrations and its endogenous biological activity, we studied the effect of iv administration of cimetidine (50-mg bolus followed by 500 mg/60 min infusion) in normal subjects and patients with primary and secondary hyperparathyroidism. No significant changes in serum concentrations of calcium, phosphate, or immunoreactive C-terminal PTH were found in any group. However, the control group had decreased calciuria, increased phosphaturia, and decreased tubular reabsorption of phosphate, while the primary hyperparathyroid group had increased phosphaturia, increased nephrogenous cAMP excretion, and decreased tubular reabsorption of phosphate. In both of these groups, the finding suggest an increase in PTH-like biological activity. These findings suggest that cimetidine is not useful in the diagnosis or medical management of hyperparathyroidism. In fact, the changes in renal calcium and phosphorous excretion indicative of PTH-like biological activity along with a decrease in creatinine clearance in the primary hyperparathyroid group suggest a relative contraindication to the use of this drug in these patients.

Structure and transcriptional status of bovine syncytial virus in cytopathic infections.

The genomic structure of bovine syncytial virus (BSV), a virus commonly infecting cattle, was examined in order to gain insights into the nature of viral DNA (vDNA) intermediates and the transcriptional status of the virus in cytopathic infections. In dog Cf2Th cells, the DNA intermediate of BSV was found to exist predominantly as linear unintegrated vDNA (uvD) molecules. The uvD molecules were cloned directly from total cellular DNA by addition of EcoRI linkers and subsequent ligation into the phage lambda EMBL4 vector. Of the eleven clones characterized, seven were full length as judged by restriction fragment analysis. The remaining four clones showed varying degrees of heterogeneity in the form of internal deletions or terminal truncations. Heat denaturation and S1 nuclease analyses were used to show that vDNA isolated from Cf2Th cells contains a single-stranded (ss) gap structure located in the central region of the genome. In addition, a double-stranded (ds) 1.3-kb fragment is observed in this vDNA population. Northern-blot analysis revealed the presence of virus-specific transcripts of 11.0, 6.4, 2.8, and 2.4 kb. This suggests that BSV is similar in complexity to the lentiviruses in terms of linear intermediates containing ss gap structures, and the presence of several RNA transcripts which may direct complex regulatory functions.

Structure of the gene encoding the beta-subunit of chicken prolyl 4-hydroxylase.

Prolyl 4-hydroxylase (EC 1.14.11.2) converts peptidyl proline to peptidyl hydroxyproline in procollagen polypeptides during collagen biosynthesis. The active enzyme is a tetramer which is composed of two pairs of non-identical subunits in a molecular form of alpha 2 beta 2. In addition to the tetrameric prolyl 4-hydroxylase (alpha 2 beta 2), the free beta-subunit is also found inside cells. Recently it was shown that the beta-subunit of prolyl 4-hydroxylase is identical to the protein disulfide isomerase and cellular thyroid hormone-binding protein. We previously isolated and characterized cDNAs of the beta-subunit of chicken prolyl 4-hydroxylase. The cDNA of beta-subunit was used to screen a chicken genomic DNA library constructed with the lambda EMBL-3 vector. Two clones, lambda gCPH beta-22 and beta-50, were isolated and characterized by restriction enzyme analysis, heteroduplex analysis, and nucleotide sequencing. The results showed that the 2.5-kb mRNA of the beta-subunit is divided into eleven exons and that the gene is 9.0 kb long. The gene contains consensus sequence for TATA at -24 bp and four CAAT at -57, -157, -194 and -223 bp in the 5' end flanking sequence of the transcription start point. In addition, there are three GC boxes upstream from the TATA box and four GC boxes in the first intron. This is similar to the structure of the alpha 1(I) collagen coding gene (COL1A1). These elements may interact with nuclear factors and play important roles in expression regulation of the beta-subunit gene as has been described in COL1A1.