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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↗
PubMed1989

Gleason grading of prostatic adenocarcinoma on fine-needle aspiration.

We attempted to use the Gleason grading scheme on fine-needle aspiration (FNA) of the prostate by examining 31 prostate aspirates that had concomitant surgical pathology tissue for correlation. A set of criteria is delineated in which it is proposed that Gleason grading is possible on FNA of the prostate by evaluating aspirated tissue fragments. Cell cytology, including qualitative nucleolar appearance, is not significantly helpful in this approach.

Adenocarcinoma↗
PubMed1989

Incidence and diagnosis of C7-T1 fractures and subluxations in multiple-trauma patients: evaluation of the advanced trauma life support guidelines.

A 5-year retrospective review was done to evaluate C-7 and C7-T1 cervical spine injuries and to assess the advanced trauma life support guidelines for cervical spine evaluation. Eighteen fractures of C-7 and four fracture-dislocation at C7-T1 were identified. Nineteen of the patients had neck pain, tenderness, or neurologic findings on initial examination. Three patients were awake and asymptomatic. The initial diagnosis could be made from lateral cervical spine x-ray film in only three of the 22 patients. In the remaining patients, the diagnosis was made by either swimmer's view (7 of 8 positive), oblique views (1 of 1 positive), flexion-extension views (2 of 3 positive), or computed tomography (CT) scan (7 of 7 positive). In two patients, the diagnosis was not made in the first 24 hours. Follow-up x-ray films were positive in 3 of 22 lateral cervical spine films, 10 of 14 swimmer's views, 2 of 3 oblique views, 2 of 3 flexion-extension views, and 14 of 20 CT scans. The data support the advanced trauma life support recommendation for liberal use of cervical spine radiologic screening. We recommend that the screening examination consist of a lateral cervical spine film, and a swimmer's view, if necessary, to visualize C-7 and the C7-T1 interspace. We further recommend that strong consideration be given to the use of a five-view trauma series. CT scan should be viewed as complementary to conventional film techniques.

Adolescent↗
PubMed1988

Effects of ibuprofen on postoperative bowel motility and propulsion.

Eighteen mongrel dogs were randomized into two groups, and all underwent right segmental colectomy. One group received ibuprofen, 12 mg/kg, preoperatively and postoperatively q6h for 24 hours; the second group served as a saline control. Propulsion was measured radiographically (q8h X 24h, then q12h) by following intraluminal radiopaque markers. Motility was measured with a multilumen monometric catheter on postoperative days 1, 2, and 3 for a 3-hour period. Propulsion, as defined by movement of more than 80 percent of the markers to the rectum, averaged 46 hours in the saline animals vs. 40.8 hours in the ibuprofen animals for an average decrease of 13 percent (P = .42). Postoperative motility showed a significant increase in the ibuprofen-treated animals on the first postoperative day (26.8 percent, P = .043), most marked at the level of the ileum (48 percent, P = .005), with insignificant differences on the second and third days. Studies comparing ileum, proximal, and distal colon suggest that ileum and proximal colon may be the major site of ibuprofen effect (10.7 percent, P = .23 and 11.96 percent, P = .41 respectively). The data suggest that ibuprofen may have a beneficial effect on postoperative bowel motility but the clinical significance of this still needs to be determined.

Animals↗
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↗
PubMed1986

Fluorescent detection of lipopolysaccharide interactions with model membranes.

We have modeled the initial interaction of bacterial lipopolysaccharide (endotoxin) with mammalian cells as consisting of two steps. The first step, adherence, we have previously shown to be ionic in nature and contains the necessary elements to determine the observed cell specificity of lipopolysaccharide interactions. The second step, coalescence, is the hypothetical insertion of the Lipid A component of lipopolysaccharide into the cell membrane lipid bilayer. Using small, unilamellar vesicles composed of phosphatidylcholine to model the cell membrane lipid bilayer, we found that lipopolysaccharide interacted with these vesicles to change the fluidity of the lipid bilayer, as measured by an increase in the fluorescence anisotropy of diphenylhexatriene in the vesicles. Since this increase in diphenylhexatriene anisotropy could not be attributed to a transfer of diphenylhexatriene between non-interacting lipopolysaccharide aggregates and vesicles, we concluded that the lipopolysaccharide aggregate coalesced with the lipid bilayer.

Cell Membrane↗
PubMed1986

The effects of methylprednisolone on postoperative bowel motility and propulsion in dogs.

Eighteen mongrel dogs underwent handsewn right segmental colectomy. One group was pretreated with methylprednisolone 30 mg/kg intravenously at the time of surgery and 7.5 mg/kg intravenously at 6-hour intervals for 24 hours; the second group served as a saline control. Motility was measured postoperatively by manometric catheters, and propulsion was measured by x-ray evidence of passage of radiopaque markers. Marker studies showed more rapid passage in animals pretreated with steroids, but differences were not statistically significant (P = 0.11). Motility studies showed a significant overall increase in motility in steroid-treated animals on the first postoperative day (P = 0.03); smaller differences on the second or third days were not significant. Motility studies comparing ileum, cecum, and sigmoid showed the ileum to be the site of significant steroid effect (P = 0.02), with insignificant benefit seen in the colon. The data suggest that methylprednisolone may be of some objective benefit in restoration of postoperative bowel motility, and the site of action may be in the small bowel and not at the anastomosis.

Animals↗
PubMed1986

Ontogeny of gastric secretion in the rat. Ultrastructural changes in relation to secretory changes.

Basal and stimulated gastric acid secretion are three to four times greater in the juvenile (30-day-old) rat than in the adult (100-day-old) rat, even though the parietal cell mass is greater in the adult. In this study we examined the possibility that the H+ secretory activity of individual parietal cells is greater in juvenile rats. To do this we used quantitative measures of secretory canaliculi and tubulovesicles as indirect measures of parietal cell H+ secretory activity. We determined that, under the experimental conditions used, the morphologic measures bear a sufficiently close linear relationship to total gastric H+ output to justify their use. We then found that when individual parietal cells from 30-day-old rats are compared quantitatively with those from 100-day-old rats, each cell from the younger rats has, on average, significantly more of the morphologic characteristics associated with higher H+ output. We inferred that individual parietal cells of 30-day-old rats, on average, may be secreting more H+ than corresponding cells of 100-day-old rats under comparable stimulation conditions.

Aging↗
PubMed1986

Sebaceous carcinoma arising from Bowen's disease of the vulva.

Sebaceous neoplasms are a marker for malignancy in the Muir-Torre syndrome. Bowen's disease has also been regarded by some as a cutaneous marker for various internal malignancies. An 89-year-old woman was noted to have a sebaceous carcinoma arising within a focus of vulvar Bowen's disease. To our knowledge, this is the first known instance of such an occurrence. The finding of a sebaceous carcinoma in association with an atypical proliferation of keratinocytic, rather than basaloid, origin is unusual and is not accounted for in most classifications of sebaceous malignancy. This observation further supports the pluripotential nature of the cell line giving rise to both Bowen's disease and sebaceous neoplasms.

Aged↗
PubMed1985

Experience with the endorectal pull-through and S pouch for ulcerative colitis and familial polyposis in adults.

An experience is reported with 23 patients who underwent rectal mucosectomy, total colectomy, creation of S-type pouch, and ileoanal anastomosis for ulcerative colitis (21 patients) or familial polyposis (two patients). There were no deaths. There were 23 complications requiring 18 operations in 16 patients. Twenty-one patients have been followed an average of 17.8 months (range 2 to 34 months) Frequency of bowel movement averaged 9.8 per day initially and 6.2 per day at the time of follow-up. None of the patients consider themselves incontinent, although 15 have had some degree of perianal soiling and at least on occasion have worn a pad. One patient intubates the pouch regularly, six intubate it on occasion, and 14 do not intubate at all. The size of the outflow treat of the pouch has been shortened from 5 to 2 cm in the last seven patients; six of these patients do not intubate and four report no soiling at all. Eleven patients have made changes in their diet or eating habits to promote more predictable bowel function and 13 take a variety of antidiarrheal medications. Nineteen patients are satisfied with the procedure and prefer the pouch to a conventional ileostomy; the other two have since undergone conversion to a Brooke ileostomy. Despite frequent bowel movements, complications, and some problems with perianal soiling, patient acceptance remains high with the endorectal pull-through and S pouch in adults, and further study, particularly using a shortened outflow tract, appears warranted.

Adult↗
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↗