Biomedical subjects

J H Peters

Publications and source records attributed to J H Peters.

At least 163 records · Page 9Linked to original sources

PubMed1992

Inhibition of human immunodeficiency virus-1 proliferation by liposome-encapsulated sense DNA to the 5' tat splice acceptor site.

A liposome formulation containing a distearoylphosphatidylethanolamine analog was developed that was endocytosed by both lymphocytes and monocytes. This formulation was used to encapsulate sense and antisense 20-mer oligodeoxynucleotides to the 5' tat splice acceptor site of human immunodeficiency virus type 1. At a DNA concentration of 140 nM, the liposome-encapsulated sense DNA inhibited p24 production by as much as 84% in human peripheral blood leukocytes infected with "wild-type" virus. This treatment also reduced the number of peripheral blood leukocytes producing intracellular viral antigen by 71%. Of interest, no reduction in either parameter was observed for the antisense-containing liposomes. The results demonstrate the promise of a new liposomal delivery vehicle to inhibit human immunodeficiency virus replication by an entrapped oligodeoxynucleotide.

Antiviral Agents↗

PubMed1992

Human blood dendritic cells exhibit a distinct T-cell-stimulating mechanism and differentiation pattern.

In this study, the mechanisms underlying stimulation of T-cell proliferation by human blood dendritic cells (BDC) and their differentiation have been defined with a panel of monoclonal antibodies (MoAbs). It was found that the MoAbs against LFA-1 (CD11a), CD11c, LFA-3 (CD58), ICAM-1 (CD54) or HLA-DR could significantly suppress T-cell proliferation in an allogeneic mixed lymphocyte reaction (P < 0.05), while being unable to inhibit clustering of BDC with T cells. Addition of anti-CD18 or CD45 MoAbs increased the size of clusters after 18 h of culture, but had no effect on the proliferation of T cells (P < 0.05). The suppressive effect of the MoAbs may be viewed not as an inhibition of contact between BDC and T cells, but rather as a blocking of co-stimulatory signals for T-cell activation, which are mediated by interaction of the adhesion molecules. After depleting the BDC preparations of monocytes, we used a double staining in FACS analysis to demonstrate that BDC do not express specific T (CD3), B (CD20 and CD21) and myeloid cell markers (CD11b, CD13 and CD14), but abundant class II antigens. This pattern remained unaltered after 8 days of culture in the presence of 100 U/ml GM-CSF, although a threefold increase of HLA-DQ and ICAM-1 molecules on the cultured cells was observed.

Antibodies, Monoclonal↗

PubMed1992

Characterization of mono- and polyclonal antibodies against highly purified choline acetyltransferase: a monoclonal antibody shows reactivity in human brain.

Choline acetyltransferase (ChAT) from porcine brain was purified by immunoaffinity chromatography, and the highly purified enzyme was subsequently used for immunization of mice and rabbits. After fusion of mouse spleen cells, 32 cultures producing monoclonal antibodies directed against ChAT were detected by an enzyme-linked immunosorbent assay (ELISA) with immunoaffinity-purified ChAT. Of these original 32, the most active 11 cultures were cloned and used for ascites production. The 11 clones generated monoclonal antibodies of the immunoglobulin (Ig) M class (three), the IgG1 subclass (seven), and the IgG2b subclass (one). The isoelectric points of the antibodies of the IgG class were different in each case. The monoclonal antibodies exhibited different binding characteristics in the above ELISA and on western blots. Two monoclonal antibodies demonstrated excellent immunohistological results with neurons of rat brain and spinal cord. One of them reacted well immunohistochemically with neurons of human brain and also recognized partially purified human placenta ChAT in the ELISA.

Animals↗

PubMed1991

IL-6 and IL-1 enhance the accessory activity of human blood monocytes during differentiation to macrophages.

The role of IL-6 and IL-1 in the regulation of accessory activity and differentiation in the human monocyte/macrophage (Mo/Mph) system was investigated. IL-6 combined with IL-1 had a strong effect on the accessory activity of Mo-derived cells dependent on their state of differentiation in vitro. Fresh Mo prepared from peripheral blood differentiated into potent accessory cells in vitro within 24 h in the absence of exogenous triggers in serum-containing and serum-free medium. Mo cultured for 2 days in the presence of the cytokines IL-6 and IL-1 did not significantly increase their spontaneous accessory activity. However, the simultaneous addition of antibodies against IL-6 and IL-1 to accessory Mo cultures significantly diminished their T cell stimulatory capacity. These findings suggest an important positive feedback role of IL-6 and IL-1, secreted by Mo at this early state of differentiation. In marked contrast, untreated mature Mph generated in vitro from Mo exhibited a low spontaneous accessory potency. However, when these cells were subjected to IL-6 and/or IL-1, we observed a strong dose dependent increase in their potency to stimulate a T cell response. Parameters indicating the differentiation of Mo to Mph, such as acid phosphatase and 5' nucleotidase, were not influenced by the addition of IL-1, IL-6, or a mixture of both and confirmed the presence of mature Mph after 6 days of culture. Based on these observations, we conclude that the monocyte-derived cytokines IL-6 and IL-1 not only directly act on T cells but may also function as a signal for accessory activity during Mo/Mph differentiation.

5'-Nucleotidase↗

PubMed1991

Historical review of pancreaticoduodenectomy.

The performance of pancreaticoduodenectomy by Whipple in 1935 demonstrated that the operation was feasible technically and compatible with reasonable function after recovery. From the mid- to late 1940s until the last 10 years, the procedure was condemned by many because of its associated mortality and morbidity. For reasons that are not clear, the risk of pancreaticoduodenectomy in the last 10 years has fallen to less than 10% and in several centers, less than 5%. Postoperative complications have been reduced and blood transfusions are unnecessary in an increasing number of patients. Furthermore, a normal productive life without the need for medication and with no digestive disorder is expected. Seventy-one percent of patients are able to return to their preoperative occupation.

Chronic Disease↗

PubMed1991

IL-4 decreases the expression of the monocyte differentiation marker CD14, paralleled by an increasing accessory potency.

IL-4 has been found to affect the phenotype and a variety of functions of human monocytes and macrophages and has been discussed as a monocyte activating protein along with other cytokines, such as IL-1 and IL-6. In this study we compared the effects of the cytokines IL-1, IL-6, IL-4, and a combination of IL-1 and IL-6 on the expression of the CD14 antigen, the FcIIIg receptor molecule CD16 and the MHC-class II molecules HLA-DR and HLA-DP. These molecules represent characteristic monocyte surface markers. Furthermore, the CD14 molecule has been described as a surface antigen of high in vivo relevance representing an indirect receptor for LPS. We further analyzed the effect of IL-4 on monocytes and macrophages with respect to their accessory function to initiate T-lymphocyte proliferation. Human peripheral blood monocytes strongly express the antigen CD14 and maintain it as a stable surface molecule during their differentiation to macrophages. Flow cytometry analysis of cultured monocytes demonstrated that cells incubated in the presence of IL-4, but not IL-1 and/or IL-6 revealed a reduced expression of the CD14 antigen in a dose- and time-dependent manner. After 3 days IL-4 treated cells were virtually CD14-negative. At the same time the expression of the CD16 antigen (FcRIIIg) was also strongly reduced, whereas the treatment with IL-4 led to an increased expression of MHC class II antigens such as HLA-DR and HLA-DP. The spontaneous low expression of HLA-DQ antigen on monocytes was not affected by any of the cytokines. Functionally, IL-4 treated CD14-negative monocytes exhibited a more than 2-fold higher activity to stimulate an accessory cell-dependent T cell proliferation. This was found in a mitogenic assay and in MLC when compared to monocytes cultured in the absence of IL-4. These observations provide further evidence that IL-4 is a major modulator of monocyte surface antigen expression. Moreover, IL-4 has an enhancer-effect on monocytes as accessory cells and therefore may be of considerable importance as a regulatory factor during monocyte development to accessory cells. Inasmuch as the CD14 molecule functions as a receptor for LPS-binding protein, our results suggest that IL-4 might also play an important regulatory role in processes initiated by bacterial lipopolysaccharides during inflammation and sepsis.

Antigen-Presenting Cells↗

PubMed1991

Immunocompetence and oxidant defense during ascorbate depletion of healthy men.

To determine nonscorbutic effects of moderate vitamin C deficiency we measured immune function and oxidative damage in eight healthy men (25-43 y) who consumed 5-250 mg/d of ascorbic acid over 92 d on a metabolic unit. During ascorbic acid intakes of 5, 10, or 20 mg/d, subjects attained a state of moderate ascorbic acid deficiency as ascorbic acid concentrations in plasma, leucocytes, semen, and buccal cells dropped to less than 50% of baseline with no scorbutic symptoms observed. No changes in cell proliferation, erythrocyte antioxidant enzymes, and DNA strand breaks were observed; however, blood levels of glutathione and NAD(P) decreased during ascorbic acid deficiency, as did delayed hypersensitivity responsiveness. Concentrations of the oxidatively modified DNA base, 8-hydroxydeoxyguanosine in sperm DNA and fecapentaenes, ubiquitous fecal mutagens, were increased during ascorbic acid depletion. Moderate vitamin C deficiency, in the absence of scurvy, results in alteration of antioxidant chemistries and may permit increased oxidative damage.

Adult↗

PubMed1991

Safety and efficacy of laparoscopic cholecystectomy. A prospective analysis of 100 initial patients.

Laparoscopic cholecystectomy quickly emerged as an alternative to open cholecystectomy. However its safety, efficacy, and morbidity have yet to be fully evaluated. During the first 6 months of 1990, we performed 100 consecutive laparoscopic cholecystectomies with no deaths and a morbidity rate of 8% (8 of 100 patients; 4 major, 4 minor). There were 81 women and 19 men, with a mean age of 46.1 years (range, 17 to 84 years). All patients had a preoperative history consistent with symptomatic biliary tract disease, and most had proved gallstones by sonography. This included four patients with acute cholecystitis. Mean operating time improved significantly from month 1 to month 6 (122 +/- 45.4 minutes versus 78.5 +/- 30 minutes, respectively), indicating a rapid learning curve. Mean hospital stay was 27.6 hours, reflecting a policy of overnight stay. Postoperative narcotic requirements were limited to oral or no medications in more than 70% of patients. A regular diet was tolerated by 83% of the patients by the morning following the procedure. Median time of return to full activity was 12.8 +/- 6.8 days after operation. In addition analysis of the hospital costs of these 100 cases demonstrates a modest cost advantage over standard open cholecystectomy (n = 58) (mean, $3620.25 +/- $1005.00 versus $4251.76 +/- $988.00). There was one minor bile duct injury requiring laparotomy and t-tube insertion, two postoperative bile collections, and one clinical diagnosis of a retained stone that passed spontaneously. Four patients required conversion to open cholecystectomy because of technical difficulties with the dissection. Although there is a significant learning curve, laparoscopic cholecystectomy is a safe and effective procedure that can be performed with minimal risk. Laparoscopic cholecystectomy should be performed by surgeons who are trained in biliary surgery and knowledgeable in biliary anatomy, and, as with all operations, it should be performed with meticulous attention to technique.

Adolescent↗

PubMed1991

Differentiation of human monocytes into CD14 negative accessory cells: do dendritic cells derive from the monocytic lineage?

Human peripheral-blood monocytes, when cultured in the absence of serum, are prevented to differentiate to macrophages (M phi). Instead, they develop into accessory cells which by various properties resemble dendritic cells. Signals that control development either into M phi or monocyte-derived accessory cells (m-AC) have been investigated by us. By applying such triggers, m-AC phenotypes and functions approached those known from lymphoid dendritic cells. Only the monocyte marker CD14, which is absent from dendritic cells, remained positive on m-AC as a last indicator of the monocytic origin of the cells. We now report that this most stable marker of the monocyte/M phi lineage can completely be down-regulated by combining tissue culture techniques with the inductive property of interleukin-4. Evidence has also been obtained by us that the conversion of monocytes into both m-AC and M phi represents a true differentiation, as demonstrated by the expression of the nuclear marker lamin A/C.

Antigen-Presenting Cells↗

PubMed1991

Blood dendritic cells carry terminal complement complexes on their cell surface as detected by newly developed neoepitope-specific monoclonal antibodies.

Blood dendritic cells carry the terminal complement complex (TCC) on their surface, as detected by three monoclonal antibodies (mAb). Two of these mAb were generated by immunizing mice with the terminal complement complex, whereas the third was generated by immunizing mice with blood dendritic cells. All three mAb are directed against neoepitopes on the C9 molecule, as assessed by binding and blocking experiments and studies with several forms of denatured C9 and C9-depleted serum. Only one of these mAb binds to soluble polymerized C9. All three mAb allow the quantification of human TCC in sensitive ELISA procedures and could be used as markers for the evaluation of the functions of non-lytic TCC on dendritic cells.

Animals↗

PubMed1991

Complications of laparoscopic cholecystectomy.

As laparoscopic cholecystectomy has become more widely practiced, the full spectrum of complications associated with this technique is being realized. We have performed 283 consecutive laparoscopic cholecystectomies with no deaths and a morbidity rate of 5.3% (15 of 283 patients; six major complications, nine minor complications). Major complications included one bile duct injury requiring laparotomy and t-tube insertion and two patients with retained stones. Symptomatic bile leakage occurred in three patients (1%). Two of these bile leaks were from accessory ducts entering the gallbladder bed; the third leak was secondary to a cystic duct leak. Eight patients (2.8%) required conversion to open cholecystectomy. Minor complications included three patients with subumbilical wound infections, two patients with urinary tract infections, one patient with costochondritis after operation, and three patients with prolonged hospital stays (more than 48 hrs) caused by ileus or fever. Several patients with life-threatening complications, including two patients who ultimately died, were transferred to our care from other centers. These included two patients with common duct injuries combined with duodenal perforations (one of whom died), one patient with a complete common duct transection, one patient with major common hepatic duct injury, and two patients with further instances of bile leakage. Laparoscopic cholecystectomy can be performed safely, and it can be associated with life-threatening complications. Prevention of complications is dependent on proper patient selection, meticulous technique, and an accepting attitude toward conversion to "open" cholecystectomy.

Adult↗

PubMed1991

Dendritic accessory cells derived from rat bone marrow precursors under chemically defined conditions in vitro belong to the myeloid lineage.

Serum-free conditions have been developed to differentiate dendritic cells from a non-adherent fraction of rat bone marrow precursors by action of the multipotential and macrophage colony-stimulating factors further supplemented with linoleic acid, vitamin E, and vitamin D3. Accessory activity was demonstrated by the high potency of the dendritic cells to stimulate autologous T cell proliferation, whereas such cells were negative for Fc receptor-dependent phagocytosis, a characteristic macrophage feature. While the dendritic cells were weakly positive for alpha-naphtylbutyrate esterase, they strongly expressed RT.1 class II antigens. Apparently, these cells represent a more differentiated phenotype since they expressed the nuclear A/C lamins. By addition of serum to the cultures, the dendritic cells developed into macrophages, which were also lamin A/C-positive as well as strongly positive for alpha-naphtylbutyrate esterase. Thus, these dendritic cells belong to the myeloid lineage, and it appears as if serum factor(s) control differentiation at a mature level. Suitable conditions could also be established for large-scale cultures of dendritic cells, which would be useful for applications requiring higher numbers of cells.

Animals↗

PubMed1991

Accessory cell function during monocyte/macrophage differentiation: relation to interleukin-1 (IL-1 beta) production and release.

Human peripheral blood monocytes (Mo) can differentiate into highly active accessory cells and approach the phenotype and function of dendritic cells instead of developing into macrophages (Mph). Here we report that monocyte-derived accessory cells (m-AC), but not Mph, spontaneously synthesize and release high amounts of interleukin-1 (IL-1 beta). Furthermore, m-AC retained a high T-cell stimulatory activity and a non-macrophagic phenotype for at least 12 days in culture. They were shown to be weakly adherent, non-phagocytic, and most of them were negative for nonspecific esterase. In contrast, Mo differentiating into mature Mph only transiently showed an elevated accessory function but at no time appeared to release intracellular IL-1 beta into the supernatant when cultured in the absence of exogenous triggers. Additionally, they gained a high phagocytic capacity and a strong expression of Fc-receptors within 4 days. Addition of lipopolysaccharides (LPS) to Mph stimulated IL-1 beta release but concomitantly led to a strong reduction of the Mph-phenotype. Thus, the release of IL-1 beta from monocyte-derived cells negatively correlated with the expression of the Mph phenotype but did not necessarily correlate with their accessory function. These observations may reflect an antagonistic regulation of Mph phenotype and cytokine release in cells of the monocytic lineage and suggest that IL-1 beta release is not essential for accessory activity but might serve rather as an autocrine signal to prolong the accessory function of m-AC.

Cell Differentiation↗

PubMed1990

Human endothelial cells synthesize, process, and secrete fibronectin molecules bearing an alternatively spliced type III homology (ED1).

Cellular fibronectin (Fn) bearing an alternatively spliced extra type III structural repeat (ED1) is normally present at low concentrations in blood plasma. The source of this material remains uncertain. In this study, primary cultures of human umbilical vein endothelial cells (HUVEC) labeled with 35S-methionine were observed to synthesize Fn monomers both with and without this segment. Monomers isolated from cell lysates with antibodies to the ED1 sequence comigrated in nonreduced sodium dodecyl sulfate polyacrylamide gel electrophoresis with the slower (designated M1), but not the faster (designated M2), of two major monomeric populations that were recognized by antibodies raised to plasma-derived Fn. The differences between M1 and M2 were not due to glycosylation, since they were also observed between species of Fn monomer purified from cells grown in the presence of tunicamycin. M1 and M2 were both observed to incorporate with a similar rate into dimeric Fn, indicating that Fn monomers with and without the ED1 site can dimerize with similar efficiency. Analysis of reduced samples of Fn isolated from cells with anti-ED1 antibodies indicated the presence of both M1-M1 and M1-M2 dimers. In addition to being incorporated into extracellular matrix, ED1 + Fn was observed to be secreted in soluble form into the medium, potentially reflecting intravascular release of this protein by endothelial cells in vivo.

Antibodies, Monoclonal↗

PubMed1990

Adenosine and its derivatives control human monocyte differentiation into highly accessory cells versus macrophages.

Human peripheral blood monocytes have been found to undergo a transitory state of high accessory activity before they fully become macrophages. Time kinetics were done to follow this accessory potential. Studying the regulation of accessory activity, we have found that monocyte-derived accessory cells (m-AC) pass through two phases of development, which both are adversely controlled by cyclic nucleotides. Phase I is positively correlated by intracellular cAMP increase and can be arrested by adenosine 3';5' cyclic monophosphate (cAMP) and synergystic agents. In addition to cAMP, non-cyclic adenine nucleotides and adenosine also mimic all cAMP effects. This behavior is explained by the known presence of surface 5' nucleotidase and adenosine receptor, which in turn leads to activation of adenylate cyclase. At phase II serum is required to convert m-AC into macrophages. In the absence of serum, cells were arrested in the m-AC state. Adenine nucleotides effectively counteract the serum induction leading to the development of m-AC even in the presence of serum. Monocyte/macrophage markers such as Fc receptors and non-specific esterase strictly correlate negatively with the expression of accessory activity. Morphologically, the appearance of veils positively correlates with all experimental situations of high accessory activity. Therefore, it is evident that serum contains regulatory factors that strongly modify the accessory potency of the m-AC via the cyclic nucleotide system, thus presenting a potent immunoregulatory principle at the beginning of the immune cascade.

Adenosine↗

PubMed1990

Increased plasma levels of ED1+ cellular fibronectin precede the clinical signs of preeclampsia.

To evaluate alterations in fibronectin homeostasis in preeclampsia we measured the plasma concentrations of fibronectin bearing an extra type III domain in 33 preeclamptic and 36 control patients at varying gestational ages. This fibronectin variant is concentrated in the endothelium of blood vessels and has been shown to be released at sites of vascular injury. In addition, total circulating fibronectin levels, composed primarily of hepatic-derived fibronectin lacking the extra type III domain, were also determined. Significant elevations in the average circulating concentrations of fibronectin with an extra type III domain (5.5 micrograms/ml [95% confidence interval, 4.7,6.2] versus 3.2 micrograms/ml [95% confidence interval, 2.9,3.5]; p = 0.0001) as well as total fibronectin (387 micrograms/ml [95% confidence interval, 357,417] versus 327 micrograms/ml [95% confidence interval, 305,348]; p = 0.036) were observed in preeclamptic versus control patients. Significant elevations in fibronectin levels with an extra type III domain occurred in the first trimester before clinical evidence of preeclampsia. In addition, multivariate logistic regression demonstrated a 5.4-fold increase in the risk of preeclampsia with each 1 microgram/ml elevation in concentration of fibronectin with an extra type III domain. These findings lend support to the hypothesis that endothelial-vascular injury is a primary event in the genesis of preeclampsia.

Adult↗

PubMed1990

Induction of nuclear lamins A/C in macrophages in in vitro cultures of rat bone marrow precursor cells and human blood monocytes, and in macrophages elicited in vivo by thioglycollate stimulation.

Hemopoietic cells from blood and bone marrow of mammals usually do not express lamins A/C but only lamin B, and this feature distinguishes these cells from the vast majority of somatic cells of the adult animal, which reveal lamins A/C as well as lamin B. Here we have cultivated rat bone marrow precursor cells and human monocytes isolated from peripheral blood in tissue culture supplemented with certain growth factors. These conditions allow bone marrow precursor cells and monocytes to differentiate almost quantitatively into accessory cells and/or mature macrophages. The different cell types in the cultures can be identified both morphologically and by other assays. Antibodies specific for mouse A/C lamins, human A/C lamins, or B lamins have been used to define the lamin complement as a function of time in culture and of cell type. A dramatic increase in lamin A/C-positive cells was observed in the first 3 days of culture with both accessory cells and macrophages expressing lamins A/C as soon as such cell types could be identified. Parallel in vivo experiments showed that treatment with thioglycollate caused the percentage of lamin A/C-positive peritoneal macrophages to increase from 5 to 80% between Days 0 and 6.

Animals↗

PubMed1990

Importance of ICAM-1 for accessory cell function of monocytic cells.

We investigated to what extent the adherence molecule ICAM-1 is important for the accessory cell function of cells of the monocyte lineage. A monoclonal antibody to ICAM-1, 7F7, inhibited the accessory cell function of human peripheral blood monocytes cultured in the presence of serum for 1-3 days. Monocyte, cultured for 4-7 days still expressed ICAM-1 but their accessory cell function was no longer inhibited by the antibody 7F7. Dendritiform accessory cells, obtained by culture of peripheral blood monocytes in serum free medium for 1-2 days also expressed ICAM-1 and their capacity to stimulate T-cells was also abrogated by antibody 7F7. These findings suggest that ICAM-1 on the surface of accessory cells of a certain differentiation stage seems to contribute to the capacity of these cells to stimulate T-cells but, that in some situations accessory cell function can occur normally without requiring ICAM-1 dependent cell to cell interactions.

Antigen-Presenting Cells↗