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Biomedical subjects

A Köhler

Publications and source records attributed to A Köhler.

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

Cutting edge: role of B lymphocytes in protective immunity against Salmonella typhimurium infection.

Infection of mice with Salmonella typhimurium gives rise to a disease similar to human typhoid fever caused by S. typhi. Since S. typhimurium is a facultative intracellular bacterium, the requirement of B cells in the immune response against S. typhimurium is a longstanding matter of debate. By infecting mice on a susceptible background and deficient in B cells (Igmu-/- mice) with different strains of S. typhimurium, we could for the first time formally clarify the role of B cells in the response against S. typhimurium. Compared with Igmu+/+ mice, LD50 values in Igmu-/- mice were reduced during primary, and particularly secondary, oral infection with virulent S. typhimurium. After systemic infection, Igmu-/- mice cleared attenuated aroA- S. typhimurium, but vaccine-induced protection against systemic infection with virulent S. typhimurium involved both B cell-dependent and -independent effector mechanisms. Thus, B cell-mediated immunity plays a distinct role in control of S. typhimurium in susceptible mice.

Administration, Oral↗
PubMed2000

Substantial in vivo proliferation of CD4(+) and CD8(+) T lymphocytes during secondary Listeria monocytogenes infection.

In mice Listeria monocytogenes infection induces a strong T cell response. In an attempt to quantitatively analyze the magnitude and kinetics of the CD4(+) and CD8(+) T cell response during L. monocytogenes infection in vivo we used a T cell transfer system that is independent of in vitro cell culture techniques and information about the identity of immunogenic T cell epitopes. Our results demonstrate substantial expansion of the in vivo primed and transferred T cell populations in response to L. monocytogenes. At the peak of response, transferred T cells represented more than one third of the total CD4(+) and CD8(+) T cell populations in blood and spleen of recipient mice. After stimulation in vitro, 40 % of these CD4(+) T cells responded to heat-killed listeriae with the production of IFN-gamma. Thus, our results reveal that in addition to the large CD8(+) T cell population an almost equally large population of Listeria-reactive CD4(+) T cells is generated in response to L. monocytogenes infection.

Adoptive Transfer↗
PubMed2000

Long-term results of low anterior resection with intersphincteric anastomosis in carcinoma of the lower one-third of the rectum: analysis of 31 patients.

INTRODUCTION: Between 1985 and 1996, 190 patients underwent a low anterior rectal resection with coloanal anastomosis for adenocarcinoma of the lower one-third of the rectum. METHODS: This article reports on 31 (17 males) of these patients with a very low localization of the tumor (distal tumor margin 1.3 +/- 0.9 cm above the dentate line). If the function of the sphincter was acceptable and we could exclude tumor infiltration into the sphincter through endosonography, we relocated the resection plane distally into the intersphincteric region to attain an acceptable margin of safety. In all of these cases, it was impossible for us to perform the usual surgical procedure of a mechanical anastomosis by means of a circular stapler. After intersphincteric rectal resection, the anastomosis was handsewn, using interrupted sutures from the perineal approach, 2.5 to 3 cm above the anal verge, implementing Parks' retractor. A protective stoma was performed in all cases. All data were documented prospectively. RESULTS COMPLICATIONS: Postoperative mortality was 0 percent. Postoperatively, none of the patients showed an indication for relaparotomy. The leakage rate was 48 percent. Only 16 percent later needed additional surgery for anastomotic strictures or for rectovaginal fistulas. Long-term observations showed that the anastomosis healed well in 27 patients (87.1 percent). Four patients (12.9 percent) decided to have a terminal colostomy performed (anastomotic stricture, 3 patients; anorectal incontinence, 1 patient). FOLLOW-UP: During the follow-up period of 6.8 +/- 3.7 years, six patients (19.4 percent) developed a tumor progression (9.7 percent local recurrences and 12.9 percent distant spread). The five-year survival rate was 79 percent (Dukes A, 100 percent (n = 18); Dukes B, 67 percent (n = 4); and Dukes C, 44 percent (n = 9)). Continence: One-third of patients developed anorectal incontinence for liquid (29.6 percent) or solid stool (3.7 percent). Average stool frequency was 3.3 times per day. Resting pressure decreased significantly by 29 percent (preoperative, 105 +/- 37 cm H2O and postoperative, 75 +/- 19 cm H2O; P < 0.05), whereas squeeze pressure did not change. CONCLUSION: In selected patients with tumors close to the dentate line, an intersphincteric resection of the rectum may help to avoid an abdominoperineal excision of the rectum with a terminal stoma, without any curtailment of oncologic standards. A protective stoma for three months is advantageous.

Aged↗
PubMed2000

[Sporotrichosis--fixed cutaneous and lymphocutaneous form].

Two patients were infected with sporotrichosis; one had the fixed cutaneous form, the other the lymphocutaneous form. Sporotrichosis schenckii was identified in both with a culture from a tissue biopsy. Both patients were successfully treated with itraconazole, one received 100 mg and the other 200 mg itraconazole daily over a 3 months period.

Adult↗
PubMed2000

A gated channel into the proteasome core particle.

The core particle (CP) of the yeast proteasome is composed of four heptameric rings of subunits arranged in a hollow, barrel-like structure. We report that the CP is autoinhibited by the N-terminal tails of the outer (alpha) ring subunits. Crystallographic analysis showed that deletion of the tail of the alpha 3-subunit opens a channel into the proteolytically active interior chamber of the CP, thus derepressing peptide hydrolysis. In the latent state of the particle, the tails prevent substrate entry by imposing topological closure on the CP. Inhibition by the alpha-subunit tails is relieved upon binding of the regulatory particle to the CP to form the proteasome holoenzyme.

Amino Acid Motifs↗
PubMed2000

Direct comparison of the sensitivity of enzyme histochemical and immunohistochemical methods: cathepsin B expression in human colorectal mucosa.

Immunohistochemical localization of the proteinase cathepsin B has been compared directly with localization of cathepsin B activity with a catalytic (enzyme) histochemical method. The 2 approaches demonstrate principally different aspects of an enzyme. The immunohistochemical method localizes the enzyme protein whether it is active or not whereas the catalytic method visualizes the functionally active enzyme only. Sensitivity of both approaches to localize low amounts of enzyme protein or activity has never been compared. In the present study, we show that cathepsin B protein has a wider distribution pattern than cathepsin B activity in human colorectal mucosa, which means that inactive cathepsin B protein is present. With respect to sensitivity of the methods, it is shown that cathepsin B protein could only be demonstrated properly when strong signal amplification was applied by using Nanogold with silver enhancement, whereas activity could be demonstrated with a simple and direct fluorogenic histochemical assay. It is concluded that catalytic histochemical methods are relatively simple methods for the localization of activity of enzymes in tissues and cells and that their sensitivity is high in comparison with immunohistochemical methods.

Catalysis↗
PubMed2000

Signal amplification in immunohistochemistry at the light microscopic level using biotinylated tyramide and nanogold-silver staining.

Signal amplification techniques greatly enhance the sensitivity of immunohistochemical (IHC) and in situ hybridization (ISH) methods. In particular, catalyzed signal amplification (CSA) using labeled tyramide or Nanogold-silver staining is an important signal amplification tool. We have applied a combination of both techniques, as has been introduced for ISH, for a further increase in sensitivity of an IHC method to detect cathepsin B. This lysosomal proteinase can also be expressed extracellularly, particularly in relation to cancer metastasis. Higher sensitivity of the IHC method was needed because existing methods failed to demonstrate cathepsin B protein where cathepsin B activity was found with a fluorescence enzyme histochemical method. Combined CSA and Nanogold-silver staining provided the sensitivity that was required. Moreover, this signal amplification method enabled the use of a 10-fold lower concentration of primary antibody (1 microg/ml). Nonspecific background staining was low provided that endogenous biotin, avidin, and peroxidase were completely blocked. The method was reproducible when all steps, and particularly the silver enhancement step, were rigidly controlled. The method resulted in localization patterns of cathepsin B protein that were in agreement with those of cathepsin B activity in serial sections of rat liver containing colon cancer metastases. We concluded that combined application of CSA and Nanogold-silver staining provides high sensitivity for immunohistochemical methods and that activity localization by an enzyme histochemical method is a very attractive alternative to IHC localization of an enzyme because it is at least as sensitive, it is rapid and simple, and it provides direct information on the function of an enzyme.

Animals↗
PubMed2000

Comparative localization of cathepsin B protein and activity in colorectal cancer.

Cathepsin B is a lysosomal cysteine proteinase that may participate in cancer progression. We compared localization of its protein and activity during progression of human colorectal cancer. In adenomas and carcinomas, protein expression and, particularly, activity were elevated compared with those in normal colorectal mucosa. In normal mucosa, cathepsin B protein expression was moderate in stroma and variable in epithelium, whereas activity was mainly present in distinct areas of stroma directly underneath the surface of the colon and in epithelium at the surface of the colon. Stroma in adenomas and carcinomas contained moderate to high protein levels but little activity except for areas of angiogenesis, inflammation, and necrosis, in which activity was high. In adenomas and the majority of well-differentiated carcinomas and moderately differentiated carcinomas, cathepsin B protein and activity were found in granular form in the epithelium, close to the basement membrane. Protein and activity levels were low and diffusely distributed in cancer cells in the remainder of the well-differentiated and moderately differentiated carcinomas and in all poorly differentiated carcinomas. Invasive fronts in most cancers contained moderate protein levels but high activity. We conclude that (a) activity localization is essential to understand the role of cathepsin B in cancer progression, and (b) cathepsin B activity in human colon is associated with invasion of cancer cells, endothelial cells, and inflammatory cells, and in cell death, both apoptotic and necrotic.

Adenomatous Polyps↗
PubMed1999

Critical role of CD28 in protective immunity against Salmonella typhimurium.

Efficient T cell activation requires both TCR signals and costimulatory signals. CD28 is one of the molecules that provide costimulatory signals for T cells. We used mice deficient in CD28 expression (CD28-/- mice) to analyze the role of CD28 in the immune response against the intracellular bacterium Salmonella typhimurium, the causative agent of murine typhoid fever. CD28-/- mice were highly susceptible to infection with wild-type S. typhimurium and even failed to control infection with attenuated aroA- S. typhimurium. More detailed analysis revealed that CD28-/- animals did not mount a T-dependent Ab response and were highly impaired in the production of IFN-gamma. Thus, CD28 cosignaling is crucial for immunity against S. typhimurium. To our knowledge, this is the first report describing an essential role for CD28 in protective immunity against an intracellular microbial pathogen.

Animals↗
PubMed1999

Development of sexually dimorphic vasotocinergic system in the bed nucleus of stria terminalis in chickens.

The bed nucleus of stria terminalis (BnST) of the domestic fowl contains two groups of parvicellular vasotocinergic neurons that are sexually dimorphic. In adult cockerels, arginine vasotocin (AVT) synthesis is well expressed in the dorsolateral and ventromedial portions of the BnST, whereas in corresponding brain areas of hens, AVT synthesis is completely lacking. In the present study, in situ hybridization and immunocytochemical methods were used to compare the ontogeny of sexually dimorphic AVT gene expression in the BnST of male and female chickens from day 12 of embryonic development (E12) until the onset of sexual maturation. By E12, both parvicellular groups of AVT-immunoreactive (AVT-ir) perikarya in the developing BnST can be distinguished in some males, whereas in females their presence is questionable. A quantitative analysis, beginning at E14, showed that the parvicellular dorsolateral portion of the BnST of male embryos had more AVT perikarya compared with females. In contrast, no evident sex difference in distribution pattern and number of AVT mRNA containing neurons in this BnST portion was observable by in situ hybridization at E15. At E18, as well as on the first and second days posthatch (D1 and D2), no differences in the number of AVT synthesizing cells and intensity of immunoreactive staining in male versus female chickens were found. Between D2 and D7, the number of AVT-ir cells in the BnST declined rapidly in both sexes until it disappeared completely in females before D35. In males, another increase in sexually dimorphic AVT-ir cells and innervation of the lateral septum was associated with the onset of puberty and fully matched a pattern observed in adult fowls. These results demonstrate that the sexually dimorphic part of the AVT system undergoes sexual differentiation during early stages of ontogeny.

Animals↗
PubMed1999

Intraspecies analysis: comparison of ITS sequence data and gene intron sequence data with breeding data for a worldwide collection of Gonium pectorale.

The morphologically uniform species Gonium pectorale is a colonial green flagellate of worldwide distribution. The affinities of 25 isolates from 18 sites on five continents were assessed by both DNA sequence comparisons and sexual compatibility. Complete sequences were obtained (i) for the internal transcribed spacer ITS-1 and ITS-2 regions of ribosomal DNA and (ii) for each of three single-copy spliceosomal introns, two in a small G protein and one in the actin gene. ITS sequences appeared to homogenize sufficiently rapidly to behave as a single copy gene. Intron sequence differences between isolates in this species reached nucleotide substitution saturation, while ITS sequences did not. Parsimony and evolutionary distance analysis of the two types of DNA data gave essentially the same tree conformation. By all these criteria, the group of G. pectorale isolates fell into two main clades, A and B. Clade A, with isolates from four continents, was comprised of four subclades of quite closely related isolates, plus one strain of ambiguous affinity. Clade B was comprised of two subclades represented by South African and South American isolates, respectively; thus, only subclades of clade B showed geographical localization. With respect to mating, all isolates except one homothallic strain and one apparently sterile strain fell into either one or the other of two mating types. Pairings in all possible combinations revealed that isolates from the same site formed abundant zygotes, which germinated to produce new, sexually active organisms. Zygotes were also formed in many pairings of other combinations, including crosses of clade A with clade B organisms, but none of the latter produced viable germlings. The ability to mate and produce viable progeny that were themselves capable of sexual reproduction was restricted to members of subclades established on the basis of DNA sequence similarities. Thus, the grades of difference in both nuclear intron sequences and rDNA ITS sequences paralleled those observed in the sexual analysis.

Actins↗
PubMed1999

[Management of primary non-classifiable anal fistulas].

UNLABELLED: In the surgery of anal fistulae, very demanding problems warranting special consideration are caused by the non-classifiable fistulae in ano. RESULTS: Of 823 patients who underwent surgery for anal fistulae between 1993 and 1996, 38 (4.5%) were, according to Parks' classification, non-classifiable; the anal canal was intact. There was no internal opening. All patients had already undergone operations, some of them multiple. In 53%, complete healing of the fistula was achieved by using a single excision. In 47% a recurrence developed. During a second revision we explored the intersphincteric space and were able to reclassify the fistulae in 50% of the cases. A continent fistulectomy led to complete healing in these patients. CONCLUSION: Non-classifiable fistulae in ano, in which an internal opening of the fistula cannot be found, can primarily be treated by a single excision of the fistula. If recurrence does occur, the patient should undergo exploration of the intersphincteric space in the region, where the cryptoglandular infection is suspected.

Adult↗
PubMed1999

Molecular cloning of a SALL1-related pseudogene and mapping to chromosome Xp11.2.

SALL1 and SALL2 have been identified as two human homologs of the region-specific homeotic gene spalt (sal) of Drosophila, which encodes a zinc finger protein of characteristic structure. SALL1 has recently been found to be mutated in patients with Townes-Brocks syndrome (TBS, OMIM No. 107480). Here we report the isolation and mapping of another sal-like human gene, named SALL1P, on chromosome Xp11.2. This intronless gene closely resembles SALL1 but displays several mutations, suggesting that SALL1P represents a sal-related pseudogene. The high similarity of SALL1P to SALL1 is of considerable importance for mutation analysis of SALL1 in TBS.

Abnormalities, Multiple↗
PubMed1999

Anaphylactic shock reaction to dibutyl-phthalate-containing capsules.

We report on a patient who was taking a Gelomyrtol forte capsule, a mucosecretolytic herbal product, to treat an infection of the upper respiratory tract. Itching, urticaria and respiratory distress occurred after 20 min which culminated in anaphylactic shock. Prick tests were carried out with the individual substances from Gelomyrtol forte capsules. Dibutyl phthalate produced a strong positive result. It is used as a plasticizer in films covering tablets, dragées and capsules. As a triggering agent of anaphylactic reactions to drugs, the auxiliary materials, e.g. dibutyl phthalate, should also be taken into consideration.

Adult↗
PubMed1998

[Evacuation defecography and defecoflometry in diagnosis of chronic constipation. A prospective comparative study of 49 patients].

Chronic constipation can be divided in two large groups: slow-transit constipation, caused by pathological intestinal transit, and obstructive defecation disorder, caused by pelvic and rectal wall abnormalities. Videodefecography and defecoflowmetry are methods used to study dynamic evacuation of the rectum. Videodefecography also enables visual estimation of rectal evacuation. Defecoflowmetry allows analysis of anal and rectal pressures. Within this prospective study we utilized and compared these methods in 19 patients with slow transit and 30 patients with obstructive disease. In patients with slow transit, both investigations demonstrated a significantly higher defecation rate than in obstructive defecation disorder (slow transit: defecoflowmetry 65%, videodefecography 80%; obstructive defecation disorder: 50% and 58%). The evacuation time was pathologically prolonged in both types of constipation, with a range of 43-55 s. Rectoceles are demonstrated in 94% of cases with slow transit and in 72% with obstructive defecation disorder. Also, we often found obstructive components in slow-transit constipation patients. Normal defecography or defecoflowmetry can rule out obstructive defecation disorder. We conclude that videodefecography and defecoflowmetry are important items in the complex diagnostic regimen needed in evaluation of chronic constipation.

Adult↗
PubMed1998

[Results of transperineal levator-plasty in treatment of symptomatic rectocele].

A rectocele is a herniation of the anterior rectal wall through the rectovaginal septum into the vagina. The most important risk factors are a previous hysterectomy, obstetic injuries and the descending perineum syndrome. In some patients the rectocele becomes symptomatical because of defecation disorders. The patients have to give manual vaginal or perineal help during defecation. Radiological parameters like the size of the rectocele or retention of barium only have limited value for the clinical evaluation. In a high percentage we find simultaneous symptoms of fecal incontinence. Transperineal anterior levatorplasty makes it possible to close the rectocele. This procedure has a positive influence on defecation and continence. In a prospective study we performed anterior levatorplasty in 35 female patients having a rectocele in combination with rectal outlet obstruction. Subjective improvement of the defecation disorder was found in 74%. Only 1 patient complained of deterioration. No patient needed manual vaginal help postoperatively. Patients who needed perineal help preoperatively had worse results. Patients who did not need any manual help preoperatively nevertheless reported an improvement postoperatively. Fifteen of 20 patients, who suffered from fecal incontinence preoperatively, reported a better continence postoperatively (75%). Even in patients with incontinence the anterior levatorplasty is a good method for rectocele repair, as it improves rectal emptying and simultaneously provides therapy for fecal incontinence.

Aged↗
PubMed1998

[Dynamic gracilis-plasty as final therapeutic possibility in anorectal incontinence].

UNLABELLED: Six patients (five women, one man with an average age of 63 years) underwent a dynamic graciloplasty. Three patients had a three- or two-stage procedure; the past three patients were treated by a one-stage procedure without any negative consequences. None of the patients received a protective stoma. COMPLICATIONS: COMPLICATIONS, needing surgical intervention occurred in two patients. In one of these patients a positive final result may still fail. RESULTS: Five patients are subjectively continent and satisfied. Four are able to retain a clysma without any problem. As a result of stimulation, three patients developed optimal anal pressures. In two patients the pressure values are satisfactory. Three patients developed evacuation problems, which up to now have been managed by laxatives. CONCLUSION: The dynamic graciloplasty is a new hope for carefully chosen patients, in whom other methods have failed.

Adult↗