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Biomedical subjects

G Leitner

Publications and source records attributed to G Leitner.

At least 37 records · Page 2Linked to original sources
PubMed2000

Access recirculation in a native fistula in spite of a seemingly adequate access flow.

True access recirculation (AR) measured by ultrasound dilution technique is usually absent in well-working shunts. It occurs with low access flows (Qa). High access flow rates are assumed to prevent AR. Two major exceptions to these rules are known: presence of intra-access strictures and inadvertently reversed blood lines. We present an additional exception in which true access recirculation occurred in a native arteriovenous (AV) fistula with correct placement of bloodlines. Surprisingly, access blood flow exceeded pump blood flow (Qb) almost threefold. The situation was clarified by a magnetic resonance angiogram showing a collateral forming a functional loop. This loop led to true access recirculation in one branch, although overall blood flow through both branches appeared to be adequate. The different findings in this shunt over time give insight into the often complex pathophysiology of native fistulae. This case proves that seemingly adequate access flow does not necessarily prevent access recirculation in native AV fistulae. We suggest monitoring both access flow and recirculation in hemodialysis accesses on a regular basis.

Adult↗
PubMed2000

Mammary infection with Staphylococcus aureus in cows: progress from inoculation to chronic infection and its detection.

The progress of Staphylococcus aureus infection from inoculation to the early chronic stage was examined in 12 Israeli-Holstein cows (four primiparous and eight multiparous) for up to 48 d after inoculation. Before inoculation, the primiparous cows were free from any infection and the multiparous cows were infected by coagulase-negative staphylococci. Two quarters in each cow were inoculated intracisternally following milking with 2000 cfu of a local prevailing Staph. aureus strain, VL-8407. Infection was established in 21 out of 24 quarters. The control quarters remained free from infection during the study, with no significant change in function. No statistically significant differences were found between primiparous and multiparous cows in the responses examined. Somatic cell count (SCC) increased within 24 h of inoculation and remained high for the duration of the study. In the infected quarters mean ln (SCC) increased within 24 h from 9.9 +/- 0.5 before inoculation to 13.0 +/- 0.2 after inoculation; most of the cells were neutrophils. N-acetyl-beta-glucosaminidase activity, expressed as ln (nnmol/min per l), was increased from 0.9 +/- 0.6 to 2.4 +/- 0.2 by inoculation, and was highly correlated with SCC. The Staph. aureus count fluctuated with no particular relationship with SCC. The phagocytic activity of neutrophils was significantly lower in the inoculated than in the control quarters and this difference increased with time after inoculation. CD8+ T lymphocytes were the main subpopulation of lymphocytes found in inoculated quarters. After inoculation, maximum but not minimum electrical conductivity (EC) recorded during milking increased significantly. The rises in maximum EC varied significantly among cows. The rises in SCC were associated with a persistent increase in EC in only one of the eight cows examined. No clinical signs were observed, and milk yield and composition were not affected during the study period. The results suggest that some strains of Staph. aureus may induce a relatively mild response in mammary glands of cows in mid lactation, and that the concomitant development of such chronic Staph. aureus infections in two quarters may not be detected by changes in the EC of composite milk and in the yield of the cow.

Acetylglucosaminidase↗
PubMed2000

Milk leucocyte populations in heifers free of udder infection.

Improvement of udder health through a process of genetic selection is related to heritability and the role of the specific trait in the probability of an individual cow developing an infection. It was suggested that different patterns of leucocyte population of the healthy gland are a significant factor in mastitis. Thus, in order to analyse the heritability of a trait and its correlation with udder health, the present study examined the leucocyte populations of uninfected mammary glands, their variability among quarters in a particular cow, and the changes that occur during lactation. Each one of the 20 cows examined was tested on average 3.06 times during lactation. The somatic cell count (SCC)/ml ranged from 12,000 to 151,000, the coefficients of determination (R2) were higher than 0.5 for SCC. No significant differences were found in the dependent variables between the sampled times (test) nor any interaction between the slopes calculated for the cows over time. No significant differences were found among quarters within a cow for any of the dependent variables including SCC. The effect of the cow trait was found to be significant for polymorphonuclear (PMN), macrophage (MO), and T-lymphocyte-bearing CD4+. The number of lymphocytes labelled with the anti-B monoclonal antibodies was negligible. In conclusion the patterns of leucocyte populations in milk together with the variance among cows should enable an analysis of the heritability of this trait and its correlation with udder health in a future study.

Animals↗
PubMed2000

Milk leucocyte population patterns in bovine udder infection of different aetiology.

This study compared the different leucocyte populations in milk from udders infected with different mastitic pathogens and in different stages of infection. Milk samples were collected from quarters free of intramammary infection, acutely infected with Escherichia coli or Staphylococcus aureus and chronically infected with S. aureus, coagulase-negative staphylococci (CNS) or Streptococcus dysgalactiae. Udder bacteriological status was confirmed after three consecutive bacteriological examinations from weekly quarter milk samples. At the time of the trial, milk samples were tested for somatic cell count (SCC) and differential cell count by both light microscopy (LM) and flow cytometry. Monoclonal antibody (mAb) CD11a/CD18 was used in order to differentiate between leucocytes and epithelial cells when tested by flow cytometry. Udder quarters free of intramammary infection had a mean SCC lower than 107 x 10(3) cells/ml in which the epithelial cells were the main cell type followed by polymorphonuclear cells (PMNs), while macrophages and lymphocytes had a lower concentration. Only 56% of the cells were labelled with the mAb anti-CD11a/CD18. In either acute E. coli- or S. aureus-infected quarters, SCC were significantly higher (P < 0.0001) than in samples from the time of inoculation, with over 90% of the cells labelled with the mAb anti-CD11a/CD18. The main cell type was neutrophils. In chronically infected cows, differences in SCC and in leucocyte patterns were found between infecting pathogens as well as between quarters harbouring the same pathogen. In all the chronically infected quarters, SCC was significantly higher (P < 0.05) than in uninfected ones. The distribution of the leucocyte patterns in the quarters infected with S. dysgalactiae did not differ from that in quarters with acute infection with both E. coli and S. aureus. In the cows chronically infected with S. aureus or CNS, the proportion of PMN was higher but not significantly different from quarters free of intramammary infection, while epithelial cells were significantly lower (P < 0.05). The T lymphocytes bearing CD4+ or CD8+ were significantly higher in quarters chronically infected with S. aureus than in quarters free of intramammary infection and in quarters acutely infected with either E. coli or S. aureus. In all samples B cells were negligible.

Animals↗
PubMed2000

Phenotypic characteristics of Staphylococcus aureus isolated from bovine mastitis in Israeli dairy herds.

A study of the characterization of the phenotypic patterns of Staphylococcus aureus strains isolated from bovine subclinical mastitis in Israeli dairy herds and their correlation with the severity of the disease was undertaken. A total of 400 chronically S. aureus-infected Israeli-Holstein cows, from 15 dairy herds were included in this study. Based on the results of the biochemical reactions, of the anti-biogram and phage typing, one major type of S. aureus was determined in each herd, its prevalence being between 54 and 100% of the total isolates from that same herd. The majority of the isolates were found to be non-haemolytic (62.7%). The most common phage type was 3/A,3/C,55,71, which was predominant in five herds. In two herds none of the isolates (24) were typable by this set of phages. All isolates were susceptible to methicillin, erythromycin, cephalotin, norfloxacin, trimethoprin-sulphamethoxazole and novobiocin. Most isolates were resistant to penicillin (96.6%) and 52% to oxytetracyclin. Differences in protein patterns between 50 and 36 kDa were found by one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. No correlation between any combination of the phenotypic characteristics was found when correlation was done with milk yield and somatic cell count, corresponding to the 6 months before sampling. Otherwise, a positive correlation was found between type of haemolysis and the N-acetyl-beta-glucosaminidase (NAGase) values. In milk from quarters infected with the-non-haemolytic strains, the level of NAGase was significantly lower (P < 0.05) than that from quarters infected with the haemolytic strains (69.7 and 105.9, respectively). However, the level of NAGase activity in the milk of the quarters infected with the non-haemolytic strains was significantly higher (P < 0.05) when compared to the milk of quarters infected with coagulase-negative staphylococci (43.5).

Animals↗
PubMed2000

Systemic and local immune response of cows to intramammary infection with Staphylococcus aureus.

The association between Staphylococcus aureus chronic mammary gland infection and the resulting immune response expressed by the production of specific IgG and IgA antibodies in blood and milk was studied in Israeli Holstein cows. Specific antibodies of the IgG class were detected in sera of 82.6 per cent of the cows chronically infected by S aureus, while in 17.4 per cent no such antibodies could be detected. Specific IgG antibodies to S aureus were neither detected in sera of cows free of mammary infection nor in those infected with different coagulase-negative staphylococci (CNS) such as S intermedius, S chromogenes or S haemolyticus. In milk, specific IgG antibodies to S aureus were detected only in cows with positive serology. The end point dilutions in the milk were 5 to 30 per cent of that of blood from the same cow. No significant difference in IgG titres was found in the same cow if the quarter was infected with S aureus or not. Specific antibodies to S aureus of the IgA class could not be detected in the sera of any of the cows included in this study. In milk, a specific IgA antibody was detected only in the samples from the S aureus infected quarters in which S aureus was isolated at the time of the experiment. In the same cow, quarters infected by S aureus were found to have a significantly higher IgA titre (P < 0.0001) than that of the non-infected ones.

Animals↗
PubMed2000

The dynamics of antibody response to Escherichia coli vaccination in meat-type chicks.

The dynamics of serum antibody (Ab) response in young broilers were studied in lines divergently selected for high (HC) or low (LC) Ab response to Escherichia coli vaccination at an early age, and their cross (HL). Chicks were divided into three vaccination-age (VA) groups: 8, 10, and 12 d of age (VA8, VA10, and VA12, respectively). Antibody response was determined five times for each chick, at 6, 8, 10, 12, and 14 d postvaccination (dPV). The effects of line, VA, and dPV on Ab titers were highly significant. The HC and LC chicks exhibited the highest and lowest mean titers, respectively, in all VA groups. The HL chicks exhibited midparent Ab values for all VA and dPV combinations, indicating additive inheritance of early Ab production. In LC, the highest mean Ab titer was obtained on Day 26 (14 dPV of the VA12 group), whereas in HC, the same titer had already been obtained on Day 18 (VA8-10 dPV and VA10-8 dPV combinations). The VA8 and VA12 chicks differed markedly in their Ab titer dynamics curves, and the VA10 chicks exhibited an intermediate curve. The three VA groups exhibited a similar change in Ab level from 6 to 10 dPV, but they differed in Ab change from 10 to 14 dPV. This significant dPV x VA interaction suggests that the VA12 and VA10, but not VA8, chicks maintained the capability to produce persisting Ab.

Aging↗
PubMed1999

Coagulase-negative staphylococci and mammary gland infections in cows.

Coagulase-negative staphylococci (CNS) are the most frequently isolated bacteria from bovine mammary gland milk samples. The objective of this study was to determine the type of inflammation evoked by CNS in the mammary gland of cows during their first lactation. Twenty-four Israeli-Holstein heifers in their first lactation were tested for bacteriological status, somatic cell count (SCC) and differential leucocyte count in milk 60-120 days postparturition and every 50-60 days after until drying off. Following the first testing, the 96 quarters of the 24 heifers were classified as follows: 69.8% as no bacterial growth (NBG), 27.1% infected with CNS and 3.1% infected with Staphylococcus aureus. During lactation, 84.5% quarters had no change in their classification, 6.2% were newly infected with other pathogens, 3.1% were classified as self-cured and in 6.2% sporadic bacteria were isolated. Among the CNS, S. intermedius, S. chromogenes and S. haemolyticus were the most frequently isolated. Milk from CNS-infected quarters had significantly higher SCC than milk from NBG quarters. An analysis of the leucocyte pattern in milk from CNS vs. NBG quarters revealed a significant increase in polymorphonuclears and a significant decrease in the percentage of total lymphocytes and lymphocytes bearing CD4+ or CD8+. The high percentage of CNS-infected quarters that remained unchanged in their bacterial status during the first lactation, indicates that those CNS have the ability to elude the immune system and persist in the mammary gland for a long time. The persisting infection, resulting to some extent from an increase of SCC by some CNS strains, suggests that in the near future control steps will have to be taken into consideration, in order to enhance the improvement of milk quality.

Animals↗
PubMed1999

Safety issues of plateletpheresis: comparison of the effects of two cell separators on the activation of coagulation, fibrinolysis, and neutrophils and on the formation of neutrophil-platelet aggregates.

BACKGROUND: Although many donors undergo repeated plateletpheresis, data on the consequences of plateletpheresis for the donor's health remain scarce. Thus, the effect of plateletpheresis on the activation of coagulation, fibrinolysis, and neutrophils was investigated. STUDY DESIGN AND METHODS: Part 1: Sixteen healthy men were randomly assigned to undergo plateletpheresis on a cell separator (AMICUS, Fenwal Baxter; or MCS 3p, Haemonetics). The effects of plateletpheresis on plasma levels of prothrombin fragment (F(1+2)), D-dimer, plasmin-plasmin inhibitor (PPI) complexes, and plasminogen activator inhibitor (PAI-1); on the activation of neutrophils (% L-selectin+); and on the frequency of platelet-neutrophil aggregates (% CD41+ neutrophils) were compared. Part 2: Ten healthy men received infusions of ACD-A and placebo without apheresis in a randomized, double-blind crossover study to control for the pharmacologic effects of citrate. RESULTS: Part 1: No change in F(1+2) occurred (p>0.05), which indicated that plateletpheresis did not enhance coagulation. Levels of D-dimer, PPI, and PAI-1 decreased over time on the AMICUS (p<0.001). Plateletpheresis did not activate neutrophils (p>0.05), but it decreased the percentage of CD41+ neutrophils (p<0.003). An approximately 80-percent drop in mononuclear cells was observed in the extracorporeal circulation of the AMICUS (p<0.001 vs. baseline and p = 0.005 vs. MCS 3p), and circulating lymphocyte and monocyte counts decreased concomitantly. Part 2: Infusion of ACD-A slightly decreased D-dimer levels (p<0.05), and both infusions decreased the circulating lymphocyte counts. CONCLUSION: Plateletpheresis can be regarded as safe with respect to the activation of coagulation or neutrophils. The consequences for the donor's health of the decrease in D-dimer, PPI, and PAI-1 may deserve further investigation.

Adult↗
PubMed1998

Leukemia-free survival and mortality in patients with refractory or relapsed acute leukemia given marrow transplants from sibling and unrelated donors.

Between April 1982 and February 1997 39 patients (24 male, 15 female) with refractory acute leukemia and a median age of 31 years (19-51 years) received allogeneic marrow grafts from an HLA-identical sibling (n = 27), HLA-identical unrelated donor (MUD; n = 10) or 1-antigen mismatched unrelated donor (n = 2). Twenty-eight patients had acute myelogenous leukemia and 11 acute lymphoblastic leukemia. For conditioning most patients received total body irradiation combined with cyclophosphamide (n = 23) or etoposide (n = 7). For graft-versus-host disease prophylaxis patients received cyclosporin A (CsA) and methotrexate (MTX) (n = 20), MTX alone (n = 3), CsA and methylprednisone (n = 6), or CsA alone (n = 10), respectively. As of June 1997 probability of leukemia-free survival projected to 3 years after BMT was 14% for patients given sibling marrow grafts and 28% after MUD transplantation. Transplant-related mortality projected to 3 years was 32% after sibling and 37% after MUD marrow grafting. Although not significantly different, probability of relapse projected to 3 years after BMT was lower after MUD at 56% compared to 78% with sibling BMT. Thus, high-dose chemo/radiotherapy followed by allogeneic marrow infusion has a curative potential for patients with refractory leukemia and offers the chance of long-term disease-free survival for some patients.

Acute Disease↗
PubMed1998

Increase in endogenous thrombopoietin in healthy donors after automated plateletpheresis.

BACKGROUND: Thrombopoietin (TPO) is a key cytokine involved in the regulation of megakaryocytopoiesis and platelet production. The aim of the present study was to test whether platelet donation is associated with changes in the serum TPO levels in healthy donors undergoing plateletpheresis. STUDY DESIGN AND METHODS: The study group consisted of 23 healthy donors undergoing single-donor plateletpheresis for the first time. Serum TPO levels and platelet counts were determined before platelet collection, at the end of apheresis, and for 4 days thereafter. Serum TPO levels were determined by a TPO-specific enzyme-linked immunosorbent assay. RESULTS: In relationship to platelet donation, serum TPO levels showed a temporary increase from baseline levels of 69.2 +/- 7.1 pg per mL to 117 +/- 6.8 pg per mL 2 days after plateletpheresis (p < 0.05). Further evaluation revealed a decline in serum TPO levels as platelet counts increased. Female donors showed a delayed normalization of circulating platelet numbers and serum TPO levels as compared to male donors. There was no significant correlation between serum TPO levels and the absolute platelet number during normalization of the donors' platelet counts after plateletpheresis. CONCLUSION: Single-donor plateletpheresis results in a temporary increase in serum TPO levels in healthy platelet donors, which may be part of a compensatory response-boosting megakaryocytopoiesis after platelet collection.

Blood Donors↗
PubMed1998

Experience with allogeneic and syngeneic blood stem cell transplantation in patients with hematological malignancies.

Between 1995 and 1997 twenty two patients with different hematological diseases ( CML n=10, AML n=6, ALL n=l, NHL n=3, SAA n=1,solid tumor n=1 ) and a median age of 37 (range, 20 to 55) years received unmanipulated peripheral blood stem cell (PBSC) transplants from HLA-identical sibling donors at our institution. Myeloablative chemotherapy consisted of cyclophosphamide (CY) and total body irradiation in 11, and chemotherapy alone in 11 patients. For graft-versus host-disease (GVHD) prophylaxis all patients were given cyclosporine A and methotrexate according to the Seattle protocol. PBSC were mobilized by granulocyte colony-stimulating factor (G-CSF) given at 10 microg/kg body weight (b.w.)/day for four days. Harvest of PBSC was started on day 5 and continued on day 6 if necessary. A median of 1 leukapheresis (range, 1 to 2) was performed and a median of 5.7 x 10(6) CD34+cells/kg b.w. (1.34 to 21.5) were obtained. Ten patients received G-CSF (5 microg/kg b.w.) starting on day one after PBSCT until neutrophil recovery. Absolute neutrophil counts >0.5 x 10(9)/L and ANC >1.0 x 10(9)/L were reached after a median of 13 (range 8 to 18) and 15 (range 9 to 19) days after PBSCT. Unsupported platelet counts >20 x 10(9)/L and 50 x 10(9)/L were reached after 17 (range 8 to 32) and 22 (range 13 to 40) days after PBSCT, respectively. Incidence of acute GVHD grade I to IV was 52%, extensive chronic GVHD occurred in 25% of patients. After a median observation time of 11 (range, 3 to 34) months twelve patients (55%) are alive and well. In summary, infusion of allogeneic PBSC after myeloablative therapy allows rapid and sustained hematologic reconstitution. Incidence of acute GVHD is not increased, for assessment of chronic GVHD longer observation times and larger patient numbers are required.

Adult↗
PubMed1998

Matched unrelated donor marrow transplantation in patients with advanced acute leukemia.

Patients with advanced acute leukemia (AL) have a poor prognosis with death due to disease or complications of therapy. High-dose chemoradiotherapy followed by allogeneic marrow transplantation (BMT) has been used to overcome resistance of the leukemic clone resulting in long-term survival of up to 20%. Due to lack of suitable related donors BMT from an HLA-compatible unrelated donor (MUD) has been increasingly applied in these patients during the last years. Between January 1991 and August 1997 twenty five patients with advanced acute myeloid (n=19) or lymphoid (n=6) leukemia, 11 males and 14 females, age 22 to 41 (median 32) years received MUD (n=22) or 1-antigen mismatched unrelated donor (n=3) grafts. In four patients an autologous BMT had been performed previously. For conditioning all patients were given total body irradiation containing regimens. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine (CSA) and methotrexate (n=24) or CSA and methylprednisone (n=1). In 23 patients (92%) class II region compatibility was assessed by DRB1, DRB3, DRB5, and DQB1 allele typing by hybridization of amplified DNA with ligation based typing. In 2 patients HLA-DR typing was performed by two colour fluorescence cytotoxicity test and mixed lymphocyte cultures. As of November 1997 10/25 patients (40%) are surviving leukemia-free after a median observation time of 17 (range, 3 to 38) months. Transplant-related mortality was an overall of 36% and 28% in patients receiving their first BMT. In 6/25 patients (24%) relapse occurred 2 to 26 months after BMT. Incidence of acute GVHD grade I to IV was 85%. The probability of relapse projected at 3 years was 35%. High-dose chemoradiotherapy followed by MUD marrow infusion has a curative potential for patients with advanced acute leukemia and offers the chance of long-term leukemia-free survival. Currently, up to 80% of patients with acute myelogenous leukemia (AML) and acute lymphoid leukemia (ALL) under the age of 50 years achieve complete hematological remission (CR) with conventional dose chemotherapy. However, in patients who are refractory to induction chemotherapy or relapse prognosis is still poor. There, high-dose chemoradiotherapy followed by allogeneic marrow infusion has been used to overcome resistance of the refractory leukemic clone and has resulted in long-term survival. For selected patients lacking a human leukocyte antigen (HLA) compatible family donor marrow transplantation (BMT) with a suitable unrelated marrow donor (MUD) has become a feasible and effective treatment. Here, we report our experience in patients with advanced acute leukemia given marrow grafts from unrelated donors.

Acute Disease↗
PubMed1997

A skin homing molecule defines the langerhans cell progenitor in human peripheral blood.

We have recently described a system for the generation of dendritic cells (DC) and Langerhans cells (LC) from defined CD34+ precursors purified from peripheral blood of healthy adult volunteers. This study has now been extended by the characterization of two distinct subpopulations of CD34+ cells in normal human peripheral blood as defined by the expression of the skin homing receptor cutaneous lymphocyte-associated antigen (CLA). CD34+/CLA+ cells from normal peripheral blood were found to be CD71LOW/CD11a+/CD11b+/CD49d+/CD45RA+ whereas CD34+/CLA- cells displayed the CD71+/CD11aLOW/CD11bLOW/CD49d(+)/ CD45RA(LOW) phenotype. To determine the differentiation pathways of these two cell populations, CD34+ cells were sorted into CLA+ and CLA- fractions, stimulated with GM-CSF and TNF-alpha in vitro, and then were cultured for 10 to 18 d. Similar to unfractionated CD34+ cells, the progeny of both cell populations contained sizable numbers (12-22%) of dendritically shaped, CD1a+/HLA-DR cells. In addition to differences in their motility, the two dendritic cell populations generated differed from each other by the expression of LC-specific structures. Only the precursors expressing the skin homing receptor were found to differentiate into LC as evidenced by the presence of Birbeck granules. In contrast, CLA precursor cells generated a CD1a+ DC population devoid of Birbeck granule-containing LC. Provided that comparable mechanisms as found in this study are also operative in vivo, we postulate that the topographic organization of the DC system is already determined, at least in part, at the progenitor level.

Adult↗
PubMed1997

Relapse of Philadelphia chromosome positive acute lymphoblastic leukaemia after marrow transplantation: sustained molecular remission after early and dose-escalating infusion of donor leucocytes.

We present a patient who underwent sibling allogeneic BMT because of refractory Ph+ve ALL and remained BCR-ABL-positive after marrow grafting. Haemopoietic precursor cells were predominantly BCR-ABL-negative and of donor origin. In T cells an exclusively donor genotype was demonstrated. Despite donor leucocyte infusion (DLI), 20 weeks after BMT BCR-ABL fusion mRNA increased in semiquantitative polymerase chain reaction and leukaemic infiltration of the patient's bone marrow was seen. After a second course of DLI the patient achieved sustained molecular remission but he developed severe graft-versus-host disease (GvHD) and died from bacterial sepsis 9 months after DLI.

Adult↗