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Biomedical subjects

H Waldner

Publications and source records attributed to H Waldner.

At least 19 recordsLinked to original sources
PubMed2002

Optimisation of sample pre-treatment in the HG-AAS selenium analysis.

A fast and accurate method of pre-treatment for biological materials in the hydride generation-atomic absorption spectroscopy (HG-AAS) selenium determination is described. All procedures of sample pre-treatment were performed in closed-vessels in a microwave oven. After sample decomposition using a HNO3/H2O2 mixture, the pre-reduction and a 'denitrification' step (reduction of interfering nitrogen intermediates) with amidosulfuric acid were combined. Hence, analysis time and the risk of element losses or the emergence of possible contamination are minimised.

Journal Article↗
PubMed2001

[Chronic fistulating wound infection after Lichtenstein repair of inguinal hernia, caused by a small colony variant of Staphylococcus aureus].

We report a case of chronic wound infection (abscess, fistula) after a Lichtenstein repair of inguinal hernia. After surgical treatment (mesh explantation), a small-colony variant (SCV) of Staphylococcus aureus was cultured microbiologically. SCV represent subpopulations of Staphylococcus aureus which are associated with chronic infections and which respond poorly to usual treatment regimes. In this case surgery and specific antibiotic treatment with flucloxacillin and rifampicin were successful.

Abscess↗
PubMed2000

[Diagnosis of acute appendicitis. Is physical examination enough to reach a surgical decision?].

In the large majority of cases, acute appendicitis can be diagnosed on the basis of the medical history and the patient's symptoms. Urine should be drawn from every patient for urinstix and bacteriological testing, as well as blood for a blood count, electrolytes and coagulation parameters. A US should be performed, in particular to exclude possible other diagnoses. Women should be examined by a gynecologist. Once the diagnosis has been established, the patient must be sent for surgery without delay. Should there be reason for doubt, further diagnostic measures (in particular CT) should be carried out as permitted by the urgency of the case. In life-threatening situations, laparoscopy should be done immediately, and preparations made for laparotomy should this be necessary. If the symptoms are such that a wait-and-see attitude is justified, continued observation and follow-up examinations are recommended. The diagnosis of acute appendicitis can be difficult, and every patient who rouses relevant suspicion, should be seen by a surgeon.

Abdomen, Acute↗
PubMed2000

Autoantigen-responsive T cell clones demonstrate unfocused TCR cross-reactivity toward multiple related ligands: implications for autoimmunity.

It has been suggested that the cross-reaction of a single T cell receptor with multiple different peptide ligands is a mechanism for maintaining a diverse yet compact immune repertoire. In the context of autoimmune disease it is important to understand how this property is balanced against the maintenance of self-tolerance. Specifically, whether the cross-reactivity inherent in the immune system is focused or unfocused will have important consequences for the development of autoimmune disease. If cross-reactivity is "focused," then in an immune response to a foreign antigen all T cell receptors that recognize the foreign antigen will cross-react with a specific autoantigenic peptide. However, if cross-reactivity is "unfocused," an immune response to a foreign antigen will result in the activation of a small number of self-reactive cells within a larger pool of cells specific for the foreign antigen. We have tested whether cross-reactivity is focused or unfocused by generating a panel of T cell clones that respond to two closely related ligands. W144 is an autoantigenic peptide of myelin proteolipid protein, PLP 139-151 (HSLGKWLGHPDKF), and Q144 is an altered peptide of PLP 139-151 bearing a glutamine for tryptophan substitution at position 144. The Q144-responsive clones have a broad degree of cross-reactivity with other position 144 substituted peptides. We find that despite their characteristic responses to Q144 and W144, the patterns of responses of these clones to other structurally related ligands are random, demonstrating that cross-reactivity is unfocused in the absence of selection. Maintaining a diverse range of cross-reactive interactions may limit nonspecific responses to autoantigens.

Amino Acid Sequence↗
PubMed2000

Fulminant spontaneous autoimmunity of the central nervous system in mice transgenic for the myelin proteolipid protein-specific T cell receptor.

Proteolipid protein (PLP)-139-151 is the dominant encephalitogenic peptide that induces experimental autoimmune encephalomyelitis (EAE) in SJL (H-2(s)) mice. To examine the contribution of T cell receptor (TCR) specificity in the induction of EAE, we generated transgenic mice expressing the rearranged TCR genes from an encephalitogenic or a nonencephalitogenic PLP-139-151/I-A(s)-specific T cell clone. Both types of transgenic lines developed spontaneous EAE, but, remarkably, the lines expressing the TCR from the nonencephalitogenic clone showed increasingly higher frequencies of disease (60-83%) in progressive SJL backcrosses and could not be propagated on the susceptible background. The T cells from the transgenic mice were not tolerized, because they responded vigorously to the antigen in vitro and mediated EAE when the mice were immunized with antigen. Besides being the only description of a TCR transgenic mice for the PLP-139-151/I-A(s) epitope, the results demonstrate that the TCR from a nonencephalitogenic PLP-specific T cell clone can induce autoimmune disease when expressed appropriately in vivo.

Amino Acid Sequence↗
PubMed1998

Heteroclitic proliferative responses and changes in cytokine profile induced by altered peptides: implications for autoimmunity.

Productive engagement of T cell receptors (TCRs) by cognate ligand (major histocompatibility complex plus peptide) leads to proliferation, differentiation, and the elaboration of effector functions. Altered peptides generated by single amino acid substitutions in the antigenic peptide have diverse effects on the outcome of the T cell response. We have generated an altered peptide (Q144) from an autoantigenic peptide of myelin proteolipid protein 139-151 by a single amino acid substitution (from tryptophan to glutamine) in the primary TCR contact at position 144 that is capable of inducing CD4(+) T cell responses in H-2(s) mice. By using a Q144-specific T cell clone (Q1.1B6), we see a hierarchy in T cell proliferation and cytokine production with various position 144 substituted peptides and have identified a peptide (L144) that hyperstimulates this T cell clone. In contrast to Q144, L144 induces maximal proliferation at 7 logs lower antigen concentration, induces greater cell death at higher antigen dose, and induces the secretion of cytokines not detected following stimulation with the cognate ligand. This heteroclitic T cell response associated with changes in cytokine profile was observed with several other T cell clones of different specificities. The L144 peptide also induces costimulation independent proliferation and cytokine production from the Q1.1B6 T cell clone. We describe this as a superagonist response. Such responses may have a role in the initiation of autoimmunity by promoting a proinflammatory environment following ligation of a cross-reactive TCR on autoreactive T cells.

Amino Acid Sequence↗
PubMed1998

Emergency laparoscopy for abdominal stab wounds.

BACKGROUND: Management strategies for abdominal stab wounds (ASW) in initially asymptomatic patients range from mandatory explorative laparotomy (EL) to conservative approaches with observation alone. Emergency diagnostic laparoscopy (DL) may play a potential role between these two extremes-hence lowering the rate of unnecessary laparotomies and keeping the rate of missed injuries to a minimum. PATIENTS AND METHODS: At our institution mandatory EL was carried out in every patient with ASW until 1992. In a retrospective study the charts of 43 patients with ASW were reviewed in terms of initial diagnostic procedures, intraabdominal injuries, and course and length of hospital stay. Between 5/1993 and 4/1995 DL was performed in a prospective study in 15 patients with suspected peritoneal penetration (PP) after ASW according to a standardized diagnostic and therapeutic algorithm. RESULTS: In 17 patients (40%) EL showed no PP; 15 (35%) had significant intraabdominal injuries, while 11 patients with PP didn't have lacerations of intraabdominal organs, resulting in an overall rate of nontherapeutic laparotomy of 65%. Mortality was 6% (n = 3), average hospital stay 8 days. Primary DL could exclude PP in 10 out of 15 patients (66%). The remaining five patients (33%) showed PP: In two patients with ASW to the right upper quadrant, intraabdominal injuries could be excluded by DL, and in one patient a low-grade liver injury was treated laparoscopically, thus avoiding laparotomy in a total of 87% (n = 13). In two patients with PP laparoscopy was converted to laparotomy: no pathological finding in one case, splenectomy for spleen laceration in the second patient, resulting in a rate of nontherapeutic laparotomies of 7%. All patients in this series had an uneventful course; average hospital stay was 2.4 days. CONCLUSIONS: DL offers an important diagnostic tool in excluding peritoneal penetration in ASW, hence lowering the rate of unnecessary laparotomies. Given experience and skills, laparoscopy may be used therapeutically in selected cases of ASW.

Abdominal Injuries↗
PubMed1998

[Effect of hypothermic preservation on ICAM-1 mRNA induction, leukocyte-endothelium interaction and microvascular perfusion after pancreas transplantation in the rat].

A prolonged period of 18 h hypothermic preservation in pancreas grafts led to a significant induction of ICAM-1 mRNA, enhanced leukocyte-adherence/-extravasation and compromised microvascular perfusion upon 2 h of reperfusion when compared to a 2 h preservation period. Therefore, during the period of prolonged cold ischemia changes within the graft must take place causing a reinforced ICAM-1 mRNA-induction already early after the onset of reperfusion. These results underline the relevance of the ischemia/reperfusion injury for the development of complications arising in the early course following pancreas transplantation.

Animals↗
PubMed1997

Fas- and FasL-deficient mice are resistant to induction of autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is an organ-specific autoimmune disease inducible in susceptible animals by myelin Ag-specific CD4+ Th1 cells. The mechanisms by which these cells induce inflammation and demyelination in the central nervous system (CNS) are incompletely understood. To determine the roles of Fas and FasL in the involvement of CNS autoimmune injury, we determined susceptibility to EAE of Fas-or FasL-deficient mice. Compared with wild-type mice, mice expressing lpr (Fas) and gld (FasL) mutations were relatively resistant to the development of clinical EAE, and this correlated with fewer inflammatory infiltrates and cells undergoing apoptosis in the CNS of the mutant mice. The gld and lpr mice, however, developed significant T cell responses with production of Th1 cytokines in response to the encephalitogenic myelin peptide. These results suggest that the Fas/FasL pathway plays a critical role in the development of EAE probably by mediating apoptosis within the target tissue.

Amino Acid Sequence↗
PubMed1997

[Perioperative standards for prevention of anastomotic insufficiency].

Anastomotic leakage is a major cause of morbidity and mortality in gastrointestinal surgery. Its incidence varies in the different segments of the GI tract being highest in the distal rectum. The rate of anastomotic leakages was reduced considerably within the last 20 years. Perioperative measures have contributed to this reduction in addition to improvements and standardization in operative technique. Perioperative nutrition, perioperative antibiotic prophylaxis and mechanical bowel preparation are widely used in colorectal surgery. Therefore they can be considered as standards. High-caloric parenteral feeding is used commonly perioperative. Its efficiency to reduce postoperative septic complications has been proven until now only for malnourished patients. The aim of perioperative antibiotic prophylaxis is to reduce the bacterial count after intraoperative contamination. Therefore tissue levels must be in the therapeutic range to cover for the expected bacteria. The efficiency to reduce postoperative wound infection has been proven, however the influence on the rate of anastomotic leakages is still controversial. Mechanical bowel preparation can reduce the bowel load but not bacterial concentration inside the bowel. Orthograde lavage with polyethylenglycol solution is feasible unless bowel obstruction is present, but its influence on anastomotic healing is still under discussion. Although all of these procedures are widely used, their influence on anastomotic healing has still to be proven by prospective, controlled trials.

Anastomosis, Surgical↗
PubMed1997

[Management of large abdominal wall hernias with foreign implant materials (Gore-Tex patch)].

OBJECTIVE: Incisional hernia repair with conventional techniques (simple closure, Mayo) is associated with high recurrence rates in the range of 30-50%. Surgical repair using different prosthetic biomaterials gains more and more acceptance. Therefore we wanted to evaluate our own results of hernia repair and analyze the results of a mesh hernioplasty using an expanded polytetrafluoroethylene patch (ePTFE). PATIENTS AND METHODS: 1. During the study period (1984-1992) a total of 205 hernia repairs (148 primary repairs, 57 repairs for recurrent hernia) were done in 173 patients at our institution using the following techniques: Mayo technique n = 90, simple one layer suture n = 56, absorbable mesh n = 25, ePTFE n = 17, other mesh techniques n = 17. In a retrospective study 135 of these patients (78%) could be examined clinically. The average follow up time was 44 months (10-105). 2. Since 1988 we used the ePTFE patch (Gore-tex Soft Tissue Patch) in selected cases for incisional hernia repair. In a second retrospective analysis the course of 26 patients, who were operated between 1988 and 1994, is reported. RESULTS: 1. Local wound complications occurred in 3-6% with conventional techniques and in 11-13% after different types of mesh repair (n.s.). Overall recurrence rates were 30% for primary hernia repair and 38% for recurrent hernia repair without statistically different rates for the various techniques. The presence of two or more patient dependent risk factors (obesity, obstructive lung disease etc.) (p < 0.05) and hernia diameter > 5 cm (p < 0.05) were identified as risk factors for hernia recurrency. 2. In the ePTFE group one patient (4%) developed a superficial wound complication, in another three patients (12%) the patch had to be removed due to deep wound infections. All three patients had revealed septic wound complications after previous surgery. The recurrence rates (17% for primary repair and 20% for repeated repair) were clearly lower compared to conventional techniques. CONCLUSIONS: The use of prosthetic mesh should be considered for repair of large or recurrent incisional hernias, especially in high risk patients (obesity, obstructive lung disease). Beside the most often used polypropylene mesh, the ePTFE patch (Gore-tex-Soft-Tissue-Patch) represents a valuable alternative in selected cases with direct contact of the prosthesis to abdominal viscera. Any previous septic wound complication or a contaminated operating field (e.g. colostomy) seems to be a contraindication for its use.

Follow-Up Studies↗
PubMed1997

[Laparoscopic versus open cholecystectomy in therapy of acute cholecystitis].

In patients with acute cholecystitis, hospital stay, blood loss, operative time and perioperative risk are compared for open and laparoscopic operations. There is a trend to wards a reduced hospital stay without any increased risk for patients with laparoscopy if critical patients are operated open.

Acute Disease↗
PubMed1996

Exogenous bradykinin enhances ischemia/reperfusion injury of pancreas in rats.

We have investigated the effect of bradykinin on microvascular perfusion failure and enzyme release after ischemia/reperfusion of the pancreas in rats. Using intravital fluorescence microscopy in 21 anesthetized Sprague-Dawley rats, quantitative analysis of the microcirculation, including functional capillary density (FCD) and leukocyte-endothelium interaction, was performed in an ischemia/reperfusion model of the pancreas. Bradykinin was dissolved in phosphate buffer and given as a bolus injection (injection group, 10 microgram/kg body wt i.a.; n = 7) or continuously infused (infusion group, 125 microgram/kg body wt/hr i.a.; n = 7) 15 min before the end of 2 hr of ischemia. Two further groups underwent sham operation (control group, n = 7) or an ischemia of 2 hr (ischemia group, n = 7) without bradykinin administration. Continuous infusion of bradykinin resulted in a significant enhancement of capillary perfusion failure after ischemia during reperfusion. In the bradykinin infusion group less than 25% of the capillaries were perfused (FCD 98 +/- 9 cm -1) after 2 hr of reperfusion, whereas in the ischemia group without bradykinin, 50% of capillaries were perfused (FCD 192 +/- 11 cm -1). Both of these values are significantly different from the baseline value of the control group (408 +/- 9 cm -1). The rise in pancreas amylase concentration was significantly more pronounced in the infusion group (basal: 1812 +/- 114 U/1; 2 hr of reperfusion 3375 +/- 268 U/1) when compared to the ischemia group (basal: 2386 +/- 283 U/1; 2 hr of reperfusion 3486 +/- 268 U/1). These findings suggest that bradykinin has an additive role in aggravation of pancreatic microcirculatory failure after ischemia/reperfusion of the pancreas.

Amino Acid Sequence↗
PubMed1996

Determinants of pancreatic microcirculation in acute pancreatitis in rats.

The aim of the study was to evaluate the effects of arterial hypotension, high-volume crystalloid resuscitation, and isovolemic hemodilution on pancreatic microvascular perfusion during acute pancreatitis. Using intravital microscopy, pancreatic functional capillary density was analyzed in rats 1 and 2 hr after onset of acute pancreatitis. Pancreatic microvascular perfusion in acute pancreatitis was characterized by a (-62%) significant reduction of functional capillary density predominantly in perinecrotic but also in nonnecrotic tissue (-43%). Pancreatic microvascular perfusion failure was aggravated by arterial hypotension but attenuated by treatment with high-volume crystalloid resuscitation. Isovolemic hemodilution was found superior to high-volume crystalloid resuscitation in maintaining pancreatic functional capillary density and therefore has the best potential in preserving tissue integrity and thereby limiting progression of disease. This study underlines the importance of early fluid resuscitation/hemodilution in patients presenting with acute pancreatitis.

Acute Disease↗
PubMed1996

[Characterization of low molecular weight zinc species in normal commercial vegetable foodstuffs].

In six different ordinary vegetables, namely kohlrabi, Chinese cabbage, chard, leak, spinach and Jerusalem artichoke, zinc was mainly found as low molecular weight species. In the present study, these important zinc compounds are further investigated. The determinations of the metal are performed by ET-AAS. The zinc complexes of all vegetables are anionic at pH 8.0 and show similar elution behaviour in gel permeation and anion exchange chromatography. Consequently, a great resemblance in structure between the low molecular weight zinc species from the different vegetables can be supposed. Exemplary, the zinc complexes of kohlrabi and Chinese cabbage are further examined. In more purified samples of these vegetables compared to zinc neither stoichiometric amounts of free protein amino acids nor nicotianamine, free malic acid, citric acid or phytic acid have been detected. Mainly glutamic acid is found in molar excess to zinc after acid hydrolysis in both cases. The cysteine contents of both zinc-binding fractions are very low. Conclusively, the well-known gamma-glutamylcysteinyl-glycines (phytochelatines) can not be responsible for the bonding of zinc in both ordinary vegetables. We suppose that zinc in kohlrabi and Chinese cabbage is bound to a glutamic acid derivative unknown as yet, possibly a malic acid ester.

Amino Acid Sequence↗
PubMed1996

The bradykinin antagonist CP-0597 can limit the progression of postischemic pancreatitis.

Bradykinin mediates the inflammatory process of acute pancreatitis characterized by an increase of microvascular permeability, vasodilation and leukocyte activation. These phenomena are characteristic also for the ischemia/reperfusion injury of the pancreas, which in time is considered a causative factor in the pathogenesis of acute pancreatitis. The aim of this study was to investigate the influence of the bradykinin B2 receptor antagonist CP-0597. After complete ischemia/reperfusion of the pancreas in rats there is progression from postischemic acute edema to necrotizing pancreatitis over a reperfusion period of 5 days. In 8 Sprague-Dawley rats (treatment group) 18 micrograms/kg/h CP-0597 was administered intraperitoneally over 5 days with an osmotic minipump starting 15 min before release of 2 h ischemia. Animals of the placebo group (n = 8) were identically treated, but received the solvent, phosphate buffer. Animals of a control group (n = 7) underwent sham operation without ischemia. After 5 days the animals were sacrificed for histology. No morphological changes of the pancreatic gland were observed in the control group. Ischemia for 2 h resulted in necrotizing pancreatitis with high mortality (4/8 animals) during the reperfusion period of 5 days. In contrast, all animals in the treatment group survived without clinical or histological signs of necrotizing pancreatitis.

Acute Disease↗