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Biomedical subjects

H Segal

Publications and source records attributed to H Segal.

At least 19 recordsLinked to original sources
PubMed2006

AML-loaded DC generate Th1-type cellular immune responses in vitro.

BACKGROUND: The generation of AML-specific T-lymphocyte responses by leukemia-derived DC has been documented by multiple investigators and is being pursued clinically. An obstacle to widespread use of this strategy is that it has not been possible to generate leukemic DC from all patients, and an alternative approach is needed if the majority of leukemia patients are to receive therapeutic vaccination in conjunction with other treatment protocols. METHODS: In the present study, we generated DC from CD14-selected monocytes isolated from healthy donor PBPC and loaded them with a total cell lysate from AML patient blasts. RESULTS: Immature in vitro-derived DC exhibited robust phagocytic activity, and mature DC demonstrated high expression of CD80, CD83, CD86 and the chemokine receptor CCR7, important for DC migration to local lymph nodes. Mature, Ag-loaded DC were used as APC for leukemia-specific cytotoxic T-lymphocyte (CTL) induction and demonstrated cytotoxic activity against leukemic targets. CTL lysis was Ag-specific, with killing of both allogeneic leukemic blasts and autologous DC loaded with allogeneic AML lysate. HLA-matched controls were not lysed in our system. DISCUSSION: These data support further research into the use of this strategy as an alternative approach to leukemia-derived DC vaccination.

Acute Disease↗
PubMed2002

Genetic basis of quinolone resistance and epidemiology of resistant and susceptible isolates of porcine Campylobacter coli strains.

AIMS: The aims of this study were to investigate the epidemiology of quinolone-resistant and -susceptible porcine isolates of Campylobacter coli and to characterize the genetic basis of quinolone resistance. METHODS AND RESULTS: Penner serotyping and flagellin gene sequence polymorphisms were used to investigate the epidemiology of the C. coli isolates. A total of 55 isolates were included, of which 30 were paired resistant and susceptible isolates from 15 pigs. Amplification of gyrA, gyrB and parC, followed by direct sequencing of amplicons was used to identify mutations in the targets of quinolones. Overall, 31 of the isolates were resistant to ciprofloxacin (minimum inhibitory concentrations (MIC), 2- >or = 32 microg x ml(-1)). Thirteen DdeI-flaA profiles were observed and resistant and susceptible strains were identified for nine profiles. The majority of resistant strains exhibited either profile 1 or 6. While profile 1 comprised susceptible and resistant strains, all of the strains with profile 6 were resistant to ciprofloxacin. The serogroup (O:24) of the profile 6 strains was identical. The only other serogroup to be uniformly associated with quinolone resistance was O:5. Strains with this phenotype comprised a number of genotypes, including profile 1. Only four of the paired isolates from individual pigs had the same profile. The genetic basis of quinolone resistance was investigated in two strains with ciprofloxacin MICs of 2 and > or = 32 miccrog x ml(-1), respectively. The amino acid substitution of isoleucine for threonine at position 86 was identified in the GyrA proteins from both strains. No mutations were identified in the GyrB proteins. CONCLUSIONS: There was an association between two of the genotypes, serotypes 5 and 24, and quinolone resistance. The association between genotype, serotype and resistance in C. coli isolates has not been reported previously. Only the mutation in GyrA associated with quinolone resistance was identified. No mutations in GyrB were identified. Amplification products of parC were not obtained and it may be that this gene is not present in some Campylobacter spp. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides data on the distribution of ciprofloxacin resistance between subtypes of C. coli.

Animals↗
PubMed2001

Chronic disseminated intravascular coagulation after surgery for abdominal aortic aneurysm: clinical and haemostatic response to dalteparin.

A 77-year-old man developed chronic disseminated intravascular coagulation (DIC) after surgical repair of a large infrarenal aortic aneurysm. Self-administered subcutaneous dalteparin therapy (5000 units o.d.) led to rapid relief of symptoms and sustained improvements in his platelet count and fibrinogen level; activation of coagulation and fibrinolysis appeared to be relatively unaffected. Long-term treatment with low-molecular-weight heparin can provide good symptomatic control of chronic DIC associated with abdominal aortic aneurysm.

Aged↗
PubMed1999

Characterization of the Acinetobacter plasmid, pRAY, and the identification of regulatory sequences upstream of an aadB gene cassette on this plasmid.

Primer extension analyses carried out to identify the transcription start site of an aadB gene, which is part of a gene cassette recombined at a secondary site on an Acinetobacter plasmid, pRAY, suggest that transcription control signals in Acinetobacter are similar but not identical to their counterparts in Escherichia coli. pRAY was sequenced. An AT-rich region, containing eight copies of the consensus sequence, AAAAAATAT, previously shown to be present in the origins of replication of other Acinetobacter plasmids, was predicted to be the origin of pRAY. The translation product of one of the 10 open reading frames identified on pRAY shows homology to the mobilization protein, MbeA.

Acinetobacter↗
PubMed1999

Gastrointestinal zygomycotic infection caused by Basidiobolus ranarum: case report and review.

Basidiobolus species are filamentous fungi belonging to the order Entomophthorales. Unlike other zygomycetes, Basidiobolus species have been mainly associated with a tropical form of subcutaneous zygomycosis in otherwise healthy individuals. Visceral disease caused by this pathogen is rare, but cases of gastrointestinal infection with Basidiobolus ranarum have been reported worldwide. In many of these reports, the inflammatory disease of the colon has been confused with Crohn's disease. We report the third case of B. ranarum gastrointestinal infection in the United States, which was initially treated as inflammatory bowel disease.

Entomophthorales↗
PubMed1999

Reconstruction of an active integron recombination site after integration of a gene cassette at a secondary site.

As the site of insertion of the aadB gene cassette on pRAY, from a clinical isolate of Acinetobacter, is almost identical to the preferred site on integrons, the composite 59-base element (59-BE) associated with this cassette is potentially recombinationally active. By using a conduction assay to quantitate site activity, the 59-BE was recognized by integrase with high frequency, indicating that the composite site is recombinationally active.

Acinetobacter↗
PubMed1999

Comparison of four methodologies for rapid and cost-effective identification of Candida glabrata.

To improve turnaround time and decrease the cost of the identification of Candida glabrata, we evaluated four methods for the detection of trehalose assimilation or fermentation. These methods were compared with the API 20C method (bioMERIEUX, Hazelwood, Mo.) to determine accuracy. We recommend the use of Remel Rapid Trehalose Assimilation Broth because of its rapid, 3-h results, reasonable sensitivity, and low number of false positives.

Candida↗
PubMed1998

Complement activation during major surgery: the effect of extracorporeal circuits and high-dose aprotinin.

OBJECTIVE: To assess the in vivo contribution to complement activation of an extracorporeal circuit and the use of high-dose aprotinin during major surgery. DESIGN: Sequential samples were obtained from 8 patients undergoing thoracic surgery, 20 patients undergoing orthotopic liver transplantation (OLT) using venovenous bypass, and 19 patients undergoing cardiac surgery using cardiopulmonary bypass (CPB). INTERVENTION: The latter two groups were part of a randomized controlled trial of high-dose aprotinin. MEASUREMENTS: Total complement activation was measured with the hemolytic complement activity and the C3 activation-specific marker, C3d antigen. MAIN RESULTS: Complement activation did not occur during thoracic surgery. During OLT, C3d antigen levels, expressed as mean +/- standard deviation (SD), were elevated from baseline at skin closure (8.6 +/- 2.5 v 13.0 +/- 5.2 mg/L; p = 0.0082). During cardiac surgery, C3d antigen levels increased 10 minutes after the start of CPB (pre-CPB, 8.0 +/- 1.9 v 14.2 +/- 3.1 mg/L; p = 0.0001) and remained at greater than baseline values postoperatively (8.0 +/- 1.9 v 11.8 +/- 2.3 mg/L; p = 0.002). There was no difference in complement activation in those receiving high-dose aprotinin during OLT or cardiac surgery. Complement activation during cardiac surgery using extracorporeal circulation occurred to a greater extent than during OLT and thoracic surgery. Complement activation during cardiac surgery or OLT was not attenuated by the use of high-dose aprotinin.

Adolescent↗
PubMed1997

Identification and characterization of an aadB gene cassette at a secondary site in a plasmid from Acinetobacter.

Transformation studies showed that an aminoglycoside resistance gene, aadB, is carried on a 6.0-kb plasmid (pRAY) in a clinical isolate of Acinetobacter (strain SUN). The gene was cloned and sequenced. An analysis of the DNA sequencing data showed that although the aadB gene is part of cassette, it is not associated with an integron. Rather, the aadB cassette has recombined at a secondary site downstream of putative promoters on pRAY.

Acinetobacter↗
PubMed1997

Engrafted human T and B lymphocytes form mixed follicles in lymphoid organs of human/mouse and human/rat radiation chimera.

BACKGROUND: We recently described a new approach that enables the generation of human/mouse chimera by adoptive transfer of human peripheral blood mononuclear cells into lethally irradiated normal strains of mice or rats, radioprotected with bone marrow from donors with severe combined immune deficiency. In such human/mouse chimera, a marked humoral response to recall antigens, as well as a significant primary response to keyhole limpet hemocyanin, has been generated. METHODS: In the present study, the organ distribution of the engrafted human cells in the human/mouse and human/rat chimera was investigated by immunohistochemistry. RESULTS: Our results show that the T cells seem to be distributed throughout the reticular endothelial system, almost behaving like particles without any homing specificity. The B cells, however, can barely be found in internal organs, such as the liver or the pancreas, and are concentrated in the secondary lymphoid system (e.g., spleen, lymph node, and nonencapsulated lymphoid tissue). The B cells, together with the engrafted human T cells, form mixed lymphoid follicles. CONCLUSIONS: The different homing patterns exhibited by the T and B lymphocytes indicate that the homing receptors on human B cells might be cross-reactive with their mouse counterparts, in contrast to the human T cells, which seem to be unable to interact with the mouse homing receptors. The presence of human B and T lymphocytes in close proximity to each other in the lymphoid tissues is in accordance with the ability of human/BALB radiation chimera to mount significant primary human antibody responses.

Adoptive Transfer↗
PubMed1997

Coagulation and fibrinolysis in primary biliary cirrhosis compared with other liver disease and during orthotopic liver transplantation.

Cirrhosis is associated with compromised hemostasis and coagulopathy during orthotopic liver transplantation (OLT). It has been suggested that hemostasis is better preserved during OLT in primary biliary cirrhosis (PBC) than other cirrhotic states. The aim of this study was to compare coagulation and fibrinolysis in 15 patients with PBC with 31 patients with other liver disease before and during OLT. Preoperatively, both groups had subnormal mean levels of prekallikrein, factor XIIa, antithrombin III (ATIII), plasminogen, and alpha2-antiplasmin. C1 esterase inhibitor and kallikrein inhibition in PBC was higher than the normal range (P < .01), but not in non-PBC. Non-PBC had lower median fibrinogen levels and shorter euglobulin clot lysis times (ECLT) (P < .05). Tissue plasminogen activator (tPA) antigen levels did not differ between groups but were elevated from the normal range, as were median thrombin-antithrombin complexes (TAT). Plasminogen activator inhibitor (PAI) activity was significantly higher in PBC (0.0041). Perioperatively in the PBC group during the early anhepatic phase of OLT, there was more thrombin generation, as evidenced by higher TAT levels (P = .0455) and less hyperfibrinolysis with longer ECLTs. We hypothesize that there is a preserved capacity to generate thrombin and less fibrinolytic activation during the anhepatic phase of OLT, and we suggest that, in PBC, the use of antifibrinolytic agents may have an adverse effect.

Adult↗
PubMed1996

Allograft and xenograft rejection in C3H/SCID mice. A new model for the study of non-T cell graft rejection mechanisms.

Comparative cell transfer experiments have revealed that, despite their equal immune deficiency, C3H/SCID mice were markedly inferior compared with C.B-17/SCID mice in their ability to accept allogeneic and xenogeneic grafts. Allogeneic C.B-17/SCID bone marrow cells were engrafted poorly compared with syngeneic C3H/SCID when transplanted into C3H/SCID recipients, whereas cells of both strains were equally well engrafted into C.B-17/SCID mice. C.B-17/SCID mice were much more permissive for outgrowth of human Burkitt lymphoma (Raji), as well as for Epstein-Barr virus lymphoma development after transplantation of human peripheral blood lymphocytes. Human skin grafts were accepted by the C.B-17/SCID mice but were promptly rejected by the C3H/SCID mice. The resistance to human RaJi cells could be adoptively transferred by infusion of C3H/SCID splenocytes into C.B-17/SCID mice. Because the C.B-17/SCID and C3H/SCID mice equally lack both T and B lymphocytes, the latter may provide a relevant model for studies of non-T mechanisms of allograft or xenograft rejection.

Animals↗
PubMed1996

Comparison of the Murex Candida albicans CA50 test with germ tube production for identification of C. albicans.

A total of 502 yeast isolates were tested with the 30-min MUREX Candida albicans CA50 (Norcross, GA) test for presumptive identification of C. albicans. The results were compared with the standard 2-h germ tube test, which was the reference standard. Of the 502 isolates, 316 were C. albicans and 186 were non-C. albicans. Identifications were based on germ tube reactions; the API20C and chlamydospore agars were used when discrepant results persisted between the germ tube and MUREX test after repeat testing of the MUREX method. A total of 16 C. albicans gave negative results on initial testing with the MUREX test but were interpreted as positive when repeated. Three germ tube negative yeasts initially tested positive with the MUREX but were negative when repeated. Two additional yeast isolates gave incorrect results with the MUREX, even with repeat testing: C. albicans and C. lusitaniae. The initial sensitivity and specificity for the MUREX C. albicans CA50 test were 94.6% and 97.8%, respectively. As an addition to the study, two fetal bovine sera were compared for production of germ tubes; fetal bovine serum and Fetal Clone II. The testing found them to be in 100% agreement.

Aminopeptidases↗
PubMed1996

Hyperfibrinolysis.

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Antifibrinolytic Agents↗
PubMed1995

Ability of bacterial endotoxin to diffuse through human dentin.

An in vitro system was developed to determine whether bacterial endotoxin is capable of diffusing through dentin without the use of filtration pressure. Cavities were prepared in five third molar teeth in order to produce a split chamber device consisting of occlusal and pulpal chambers with 0.5 mm of intervening dentin. Endotoxin was introduced into the occlusal chamber and the effluent in the pulpal chamber was sampled every 30 min for 5 h and at 24 h using the limulus lysate assay. In four specimens the initial appearance of endotoxin in the effluent ranged from 15 min to 4 1/2 h. In two specimens the concentration of endotoxin in the effluent leveled off in 4 1/2 and 5 h, respectively, whereas in another two the concentration continued to increase throughout the experiment. In one specimen no endotoxin was detected. The results indicate that endotoxin is capable of passing through 0.5 mm of dentin.

Aggregatibacter actinomycetemcomitans↗