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D M Jacobs

Publications and source records attributed to D M Jacobs.

At least 19 recordsLinked to original sources
PubMed1992

Use of o-phthalaldehyde to detect O-phosphorylethanolamine in bacterial lipopolysaccharide.

We have developed a method to measure O-phosphorylethanolamine groups in bacterial lipopolysaccharide using a fluorescent reagent, o-phthalaldehyde. The optimal excitation and emission wavelengths were 335 nm and 450 nm, respectively. The reaction was pH-dependent with an optimum at pH 10.5. The maximum fluorescence intensity occurred two min after mixing lipopolysaccharide with the reagent at pH 10.5. The assay was linear over a range of 1 microgram to 100 micrograms of lipopolysaccharide. When we compared the amount of primary amine (as O-phosphorylethanolamine) in native and p-hydroxyphenylacetic acid-derivatized lipopolysaccharide, we found that 97% of amine groups in native lipopolysaccharide were derivatized by p-hydroxyphenylacetic acid in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide.

Ethanolamines↗
PubMed1992

Characterization of lipopolysaccharide fractions and their interactions with cells and model membranes.

The role of the length of the O-antigen polysaccharide side chain of bacterial lipopolysaccharide (LPS) in biological and model membrane systems was investigated. LPS from Salmonella typhimurium ATCC 14028 was chromatographed on a Sephadex G-200 column in the presence of sodium deoxycholate and separated into three fractions on the basis of molecular size. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot (immunoblot), and chemical analyses indicated that these fractions differed from each other primarily in the number of repeating units in the O-antigen polysaccharide side chain. In a biological system fractions 2 and 3 had the same effects to induce mitogenesis in murine lymphocytes, but fraction 1 was less effective than the other two fractions. In a model membrane system, LPS induced changes in small unilamellar vesicles (SUVs) which were measured by changes in the behavior of a fluorescent probe, 1,6-diphenylhexa-1,3,5-triene (DPH), and interaction of increasing amounts of all LPS fractions with SUVs gradually increased DPH anisotropy. Fractions 2 and 3 had similar effects on the SUVs as detected by changes in DPH anisotropy, while fraction 1 had almost twice as much activity as the other two fractions. These results suggest that the polysaccharide side chain of LPS may modulate the ability of biologically active lipid A to interact with cells and model membranes. In addition, factors other than changes in membrane fluidity may play a role in mediating LPS-induced cell activation.

Animals↗
PubMed1991

Comparative intrinsic and extrinsic compliance characteristics of S, J, and W ileoanal pouches.

Although compliance of the ileoanal reservoir pouch has been shown to affect function, previous compliance studies may have been influenced by the compliance of the small bowel proximal to the pouch and by supporting pelvic structures. The following study was designed to isolate the pouch and to compare intrinsic and extrinsic factors influencing pouch compliance. Thirty-three mongrel dogs underwent rectal mucosectomy and proctocolectomy with S-pouch (S) in nine, stapled J-pouch (SJ) in nine, handsewn J-pouch (HJ) in nine and handsewn W-pouch (SW) in six. At 2 weeks, each dog underwent laparotomy, the small bowel 2 cm proximal to the pouch was clamped, and in vivo pouch compliance was measured using anal balloon occlusion and continuous saline infusion manometry. The pouch was then removed and ex vivo measurements were repeated. Mean compliance slopes between 0 and 40 cm H2O were compared by ANOVA and paired t-tests. In vivo and ex vivo compliance in ml/cm H2O was 3.1 +/- 1.2 and 3.8 +/- 1.6 (P = 0.25) for the S-pouch, 3.1 +/- 0.6 and 5.2 +/- 1.7 (P less than 0.01) for the SJ-pouch, 2.3 +/- 0.5 and 4.8 +/- 0.7 (P less than 0.001) for the HJ-pouch, 3.6 +/- 0.6 and 6.0 +/- 0.7 (P less than 0.001) for the W-pouch. Pearson's correlation coefficient for in vivo and ex vivo measurements of the S, SJ, HJ, and W pouches were r2 = 0.066, 0.001, 0.039, and 0.379, respectively. It is concluded that: 1) Isolated pouch compliance can be accurately measured in experimental animals with proximal and distal occlusion and inflow manometry. 2) In vivo compliance is significantly less in the HJ compared with S, SJ, and W pouches. 3) Differences between in vivo and ex vivo compliance of SJ, HJ, and SW pouches are significant. 4) In vivo and ex vivo compliance determinations correlate poorly. 5) Extrinsic factors contribute significantly to pouch compliance.

Anal Canal↗
PubMed1991

Iron chelation with a deferoxamine conjugate in hemorrhagic shock.

Oxygen-derived radicals are cytotoxic, highly reactive molecules that contribute to cellular death and injury in hemorrhagic shock. Iron released into the plasma in hemorrhagic shock may contribute to cellular damage by catalyzing lipid peroxidation of cell membranes. Deferoxamine (DFO) chelation of transitional metal ions prevents formation of these radicals and may diminish reperfusion injury. The conjugation of DFO to pentastarch (PS) decreases DFO toxicity and extends its half-life making it a potentially useful resuscitative fluid. A porcine hemorrhagic shock model was used to evaluate the effects of five resuscitative fluids on survival and hepatic function. Swine (11-16 kg) underwent splenectomy, liver biopsy, and placement of arterial and venous catheters. Awake animals were bled at 1 ml/kg/min to a MAP of 45 mm Hg, maintained for 1 hr, and resuscitated over 30 min with one of five fluids: Lactated Ringer's (LR); LR + free DFO 2.5 mg/ml (LR + DFO) (n = 6); 5% PS in LR (PS) (n = 6); 5% PS + free DFO (PS + DFO) 7.5 mg/ml (n = 6); 5% PS/DFO conjugate (7.5 mg/ml) in LR (n = 6). LR and LR + DFO received 3 ml/ml shed blood; PS, PS + DFO, and PS/DFO received 1 ml/ml shed blood. No shed blood was returned to the animals. There was no significant differences between groups in MAP, HR, CVP, and T pre- and post-resuscitation. No LR lived to sacrifice at 24 hr. Thirty-three percent of LR + DFO and PS + DFO animals died within minutes of receiving the free DFO containing resuscitative fluid, presumably from acute DFO toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Eyeballing.

Explore the source record for details and available documents.

Calibration↗
PubMed1990

Fluorescent detection of lipopolysaccharide interactions with model membranes.

The critical importance of the lipid A moiety of LPS in resistance and pathogenesis in gram negative infections has led to the assumption that LPS interaction with target cells is due to hydrophobic interaction with plasma membranes. However, work from several laboratories, including our own, is consistent with the presence of a cell membrane structure with characteristics of a "receptor". We have proposed a two-step model for LPS-membrane interaction which resolves the two views, and have developed a model system to control the first step (binding to membrane protein) and study the second step (intercalation into lipid bilayer). We examined the interaction of LPS with small unilamellar phosphatidylcholine vesicles labeled in the hydrophobic portion of the bilayer with the fluorescent probe diphenylhexatrine (DPH) and detected changes in the physical properties of the bilayer by measuring DPH fluorescence anisotropy (delta r). We have found that purified, phenol-extracted S. typhimurium LPS interacts with the bilayer as measured by an increase in delta r and conclude that the LPS aggregate coalesced with the lipid bilayer. The greatest change in delta r was achieved with lipid A, Ra-Re glycolipids and diphosphoryl lipid A. Monophosphoryl lipid A and lipid X were less effective. Preparations of wild-type LPS fractionated according to the length of the O-antigen side chain and unfractionated LPS had least effect on delta r. Thus other factors such as serum components or membrane proteins may be necessary to enhance the interaction of LPS with target cells.

Carbohydrates↗
PubMed1990

Experience with the biofragmentable anastomotic ring (BAR) in bowel preoperatively irradiated with 6000 rad.

Previous studies from the authors' laboratory using the biodegradable anastomotic ring (BAR) have demonstrated the safety of this device in animals irradiated preoperatively with the equivalent of 5000 rad; sutured, stapled, and BAR anastomoses all had leak rates of 10 percent or less in this setting. This study was undertaken to assess the safety of the BAR after irradiation with the equivalent of 6000 rad. Thirteen mongrel dogs underwent preoperative irradiation to the rectum and rectosigmoid, receiving 6000 rad according to the nominal standard dose equation. After a three-week rest period, each dog underwent anterior resection of the rectosigmoid and anastomosis with the BAR. The anastomoses were evaluated for early and late healing and anastomotic leaks. The results were compared with previous data from the authors' laboratory using an identical model. Radiographic leaks were found in 7 of 10 sutured anastomoses, 8 of 10 stapled anastomoses, and 3 of 13 BAR anastomoses (P less than 0.01). Comparative clinical leaks were 5 of 10 for sutured, 5 of 10 for stapled, and 3 of 13 for BAR anastomoses. These data suggest that the BAR may offer added safety to an anastomosis after preoperative irradiation. Whether this effect is due to the atraumatic technique of placing the device, improved blood flow to the anastomotic margins, or other factors, is still underdetermined.

Anastomosis, Surgical↗
PubMed1987

Basal cells of prostate in fine-needle aspiration.

Fine-needle aspiration in conjunction with a transrectal core biopsy was performed on a 58-year-old man who presented with a prostate nodule. The aspirate contained many cell clusters that were negative for prostatic acid phosphatase and cytologically appeared to be basal cells. The entity of basal cell hyperplasia of the prostate is discussed with reference to its appearance in aspiration cytologic examination. Emphasis is placed upon the possibility that these cells may be mistaken for cancer cells.

Adenocarcinoma↗
PubMed1979

A solid-phase radioimmunoassay for bacterial lipopolysaccharide.

A radioimmunoassay for E. coli 055:B5 lipopolysaccharide (LPS) is described. The LPS was derivatised by two new methods and subsequently radiolabeled with 125I to a specific activity of 2-4 mCi/mg without apparent loss in its biophysical, immunological or biological activities. Using antibody-coated polystyrene tubes, a solid-phase radioimmunoassay was developed with a sensitivity of 10-500 ng/ml of LPS.

Animals↗
PubMed1979

Synergy between T cell-replacing factor and bacterial lipopolysaccharides (LPS) in the primary antibody response in vitro: a model for lipopolysaccharide adjuvant action.

Unfractionated spleen cells, B cells from normal mice, and nu/nu spleen cells respond to the addition of bacterial lipopolysaccharide (LPS) and T-cell-replacing factor (TRF) by production of plaque-forming cells (PFC) in excess of the number expected from the addition of LPS and TRF separately. This synergistic activity is dependent on the presence of the antigen, SRBC. Supernatants of both allogeneic spleen cell mixtures and spleen cells cultured with Con A are effective and synergize best at concentrations suboptimal for their ability to act as TRF alone. Culture supernatants of unstimulated normal or fractionated cell populations are ineffective. Synergy is not dependent on the presence of macrophages in the cultures. Purified LPS free from active contaminants, as well as commercially available LPS, show synergy with TRF. Synergy was seen when TRF was added at initiation of culture or 24 hr later. It is suggested that synergy is the equivalent of LPS adjuvant activity, that the role of T cells in LPS adjuvanticity is that of a conventional cooperating cell, and the LPS acts as an adjuvant by inducing B cells to become more sensitive to T cell helper factors.

Adjuvants, Immunologic↗
PubMed1978

Modulation of immune response by bacterial lipopolysaccharide (LPS): cellular basis of stimulatory and inhibitory effects of LPS on the in vitro IgM antibody response to a T-dependent antigen.

The role of thymus-derived lymphocytes (T cells) in LPS modulation of T cell-dependent antibody responses has been investigated. We have assessed the effect of LPS on the primary anti-TNP response to TNP-SRBC of cultures of whole spleen cells or T cell-depleted spleen cells that were supplemented with various subpopulations of carrier-primed (SRBC) spleen cells. The TNP-PFC response was enhanced in the presence of irradiated SRBC-primed spleen cells by addition of 0.16 to 20 microgram/ml LPS, but inhibition was observed when irradiation of primed cells was omitted. Enhancement but no inhibition occurred when added primed cells were first passed through a nylon wool column. LPS-mediated enhancement was dependent on a T cell in the primed population. These results suggest that LPS modulation of antibody synthesis is dependent on two populations of antigen-specific cells that have opposing effects on B cell responses to a T-dependent antigen: a helper cell that is irradiation resistant, nonadherent to nylon wool, and sensitive to anti-T cell serum, and a suppressor cell that is irradiation sensitive and adherent to nylon wool.

Animals↗
PubMed1978

Modulation of immune response by bacterial lipopolysaccharide (LPS): multifocal effects of LPS-induced suppression of the primary antibody response to a T-dependent antigen.

Spleen cells from mice injected with 2 to 50 microgram bacterial lipopolysaccharide (LPS) have a reduced capacity to make an antibody response in vitro to trinitrophenylated sheep erythrocytes (TNP-SRBC) when tested 1 to 7 days later. Recovery is gradual, and these cells are full functional 2 weeks after in vivo LPS treatment. Unresponsiveness resides in the nonadherent splenic cell populations, and can be shown to have a suppressive cell component, which is irradiation sensitive and has somme characteristics of a thymus-derived lymphocyte (T cell). In addition, neither bone marrow-derived lymphocytes (B cells) nor T cells in the spleens of LPS-treated mice are functionally normal in their abilities to cooperate during an antibody response in vitro. LPS-B cells cooperated poorly with nylon wool-enriched T cells from normal mice but cooperated well with irradiated carrier-primed T cells or nylon wool-purified splenic T cells from carrier-primed mice. LPS-T cells have a reduced capacity to interact with normal B cells and appear to contain a suppressor cell component. These results indicate that the effects of exposure of immunocompetent cells to LPS are multifocal and can include suppression as well as stimulation of antibody formation.

Animals↗
PubMed1977

Inhibition of the mitogenic response to lipopolysaccharide (LPS) in mouse spleen cells by polymyxin B.

The addition of low doses of the cationic polypeptide antibiotic, polymyxin B (PB), to cultures of mouse spleen cells inhibits lipopolysaccharide-(LPS) induced DNA synthesis but not that stimulated by PPD, PHA, or Con A. Inhibition is stoichiometric; the mitogenic response is suppressed by 50% at a weight ratio of PB:LPS of 0.055 to 1. Furthermore, PB-LPS complexes have a much reduced mitogenic capacity. These complexes inhibit the mitogenic response of spleen cells to unmodified LPS but not to PPD, Con A, or PHA. The inhibitory activity of PB is less effective when added after LPS is mixed with responding cells, achieving 50% inhibition when addition is made at 4 to 6 hr. Time course experiments indicate that partial inhibition is a reflection of a lower rate of DNA synthesis. Thus, PB inhibition of LPS mitogenesis apparently occurs as a result of formation of PB-LPS complexes with reduced mitogenic capacity. Specific inhibition by the complexes of mitogenesis induced by native LPS suggests that the inactive complex may bind to B cells but is unable to trigger them.

Animals↗
PubMed1976

Isolation of a lipid A bound polypeptide responsible for "LPS-initiated" mitogenesis of C3H/HeJ spleen cells.

The experiments by Sultzer and Nilsson (1), and later by Watson and Riblet (2), established that spleen cells from the C3H/HeJ strain of mouse were refractory to the mitogenic effects of bacterial lipopolysaccharides (LPS). More recently, however, experiments from our laboratory (3) demonstrated that spleen cells from C3H/HeJ mice were in fact responsive to some preparations of LPS but not to others, and that the method of extraction played a critical role in determining activity. In particular, preparations of LPS prepared by extraction with aqueous butanol had potent mitogenic activity. Our data showed that the mitogenic activity of such positive preparations of LPS coisolated with the LPS during gel filtration chromatography and subsequent equilibrium banding on CsCl. In addition, lipid A isolated from positive preparations of LPS was also capable of stimulating C3H/HeJ spleen cells. Taken together, these experiments provided rather convincing data that it was the LPS (in particular the lipid A) itself, or some contaminant very tightly bound to the lipid A, which was responsible for its biological activity. We further demonstrated that treatment of positive preparations of LPS with hot phenol rendered such preparations nonmitogenic for C3H/HeJ spleens, yet activity for other strains was only moderately decreased. These experiments would suggest either that the phenol treatment chemically alters the lipid A region of the LPS molecule or that such treatment removes the putative tightly bound contaminant responsible for C3H/HeJ mitogenesis. In the experiments reported here, we have explored in greater detail the role of lipid A in the stimulation of C3H/HeJ spleen cells. For these experiments we have utilized our earlier observations that the antibiotic polymyxin B forms a highly stable molecular complex with the lipid A region of LPS (4), and that such polymyxin B-LPS complexes are unable to mitogenically stimulate B lymphocytes (5). In addition, we have attempted to distinguish between the two potential modes of action of phenol on LPS, namely, the chemical alteration of the lipid A or the removal of a tightly bound contaminant by phenol treatment. The results of the experiments we report here support the interpretation that mitogenic activity of positive preparations of LPS is associated with a low mol wt phenol soluble polypeptide of approximately 10,000 mol wt. After partial purification, this polypeptide intitiates a significant mitogenic response at concentrations as low as 10 mug/ml. We conclude that the C3H/HeJ strain of mouse is a true nonresponder to the stimulatory effects of the lipid A region of LPS.

Animals↗