Biomedical subjects

T Kocher

Publications and source records attributed to T Kocher.

At least 55 records · Page 3Linked to original sources

PubMed2001

Genetic and ecological divergence of a monophyletic cichlid species pair under fully sympatric conditions in Lake Ejagham, Cameroon.

Although there is mounting evidence that speciation can occur under sympatric conditions, unambiguous examples from nature are rare and it is almost always possible to propose alternative allopatric or parapatric scenarios. To identify an unequivocal case of sympatric speciation it is, therefore, necessary to analyse natural settings where recent monophyletic species flocks have evolved within a small and confined spatial range. We have studied such a case with a cichlid species flock that comprises five Tilapia forms endemic to a tiny lake (Lake Ejagham with a surface area of approximately 0.49 km2) in Western Cameroon. Analysis of mitochondrial D-Loop sequences shows that the flock is very young (approximately 10(4) years) and has originated from an adjacent riverine founder population. We have focused our study on a particular pair of forms within the lake that currently appears to be in the process of speciation. This pair is characterized by an unique breeding colouration and specific morphological aspects, which can serve as synapomorphic characters to prove monophyly. It has differentiated into a large inshore and a small pelagic form, apparently as a response to differential utilization of food resources. Still, breeding and brood care occurs in overlapping areas, both in time and space. Analysis of nuclear gene flow on the basis of microsatellite polymorphisms shows a highly restricted gene flow between the forms, suggesting reproductive isolation between them. This reproductive isolation is apparently achieved by size assortative mating, although occasional mixed pairs can be observed. Our findings are congruent with recent theoretical models for sympatric speciation, which show that differential ecological adaptations in combination with assortative mating could easily lead to speciation in sympatry.

Age Factors↗

PubMed2001

Pseudotumor of the pancreatic head associated with idiopathic retroperitoneal fibrosis.

A 68-year-old male presented with abdominal pain and obstructive jaundice. CT revealed a large mass in the pancreatic head that was initially interpreted as pancreatic carcinoma. Needle biopsy revealed only fibrous tissue with signs of chronic inflammation. Together with typical findings of an idiopathic retroperitoneal fibrosis, the final diagnosis of multifocal idiopathic fibrosclerosis with focal pseudotumorous pancreatic head fibrosis could be made.

Aged↗

PubMed2000

Identification of genes differentially expressed in melanoma sublines derived from a single surgical specimen characterised by different sensitivity to cytotoxic T-lymphocyte activity.

In this study we used differential display technology in an attempt to obtain an insight into the mechanisms underlying escape of tumour cells to the specific cytotoxic T cell response. A primary tumour cell line and autologous tumour infiltrating lymphocytes were raised from a metastatic melanoma sample (ME15). Upon co-culture of tumour infiltrating lymphocytes with irradiated tumour cells, CTL specific for neoplastic cells were generated and cloned. Using a CTL clone, a cytotoxicity resistant tumour subline (ME15R) was immunoselected. We applied a PCR-based differential display technique to amplify DNA sequences differentially expressed in ME15 sublines sensitive (S) or resistant (R) to specific CTL killing. 10 different sequences whose expression was exclusively detectable in ME15S cells were identified. Five of them matched with known expressed sequence tags encoding products of unidentified function. 2 showed high homology with a mitochondrial mRNA and with the gene encoding the S24 ribosomal protein. Most interestingly, genes coding for glutamine synthetase, TGF-beta-3 and PAX3, a well-characterised transcription factor, were only expressed in ME15S cells. The latter gene was found to be transcribed in all healthy tissues tested, but only in a subgroup of established melanoma cell lines. Taken together, our data underline the relevant potential of differential display technology in the molecular analysis of paired tumour lines endowed with different phenotypic characteristics. Cloning of entire open reading frames and transfection studies are warranted to clarify the role of individual differentially displayed genes in the escape of tumour cells from cellular immune response.

Base Sequence↗

PubMed2000

FLT3 ligand gene expression and protein production in human colorectal cancer cell lines and clinical tumor specimens.

Dendritic cells (DC) are professional antigen presenting cells (APC) whose proliferation and functional differentiation can be induced by hematopoietic growth factors including GM-CSF and FLT3 ligand (FL). Colorectal cancers are known to be infiltrated by dendritic cells (DC) and neoplastic cells have been shown to produce GM-CSF. In this work we investigated FLT3 ligand (FL) gene expression and protein production in human colorectal cancer cell lines and clinical tumor specimens. Using reverse transcription polymerase chain reaction (RT-PCR), 6 out of 6 established tumor lines were found to express to variable extents FL gene. In 1 of them, SW480, FL immunoreactivity could be observed by taking advantage of specific antibodies. In contrast, soluble FL could not be detected in any culture supernatant. FLT3 receptor (FR) gene was not expressed and exogenous addition to the cultures of recombinant FL (rFL) did not affect the proliferation of the tumor lines. FL gene expression was investigated using a densitometry-assisted, semiquantitative RT-PCR in clinical tumor specimens. Specific FL gene transcripts were amplified from 12 of 12 surgical samples. In these cases, FL gene expression of significantly lower intensity was also detected in healthy mucosa sampled in the vicinity (2 cm) or at a distance (10 cm) from neoplastic outgrowth. Immunohistochemical studies identified FL-positive cancer cells in 5 of 5 cases tested. No positivity was detected in healthy mucosa epithelia at a distance from the tumor or in stromal cells. FL content in preoperative sera from colorectal cancer patients (n = 13) did not exceed the levels detected in healthy donors (</= 100 pg/ml).

Colorectal Neoplasms↗

PubMed2000

Polymorphism of the N-acetyltransferase (NAT2), smoking and the potential risk of periodontal disease.

Periodontal disease is a common multifactorial process that leads to bone destruction and tooth loss. Interactions of environmental and genetic factors determine the extent and severity of periodontal disease. Smoking is one of the risk factors for periodontal disease, and the risk may be influenced by the polymorphism of N-acetyltransferase (NAT2) via metabolism of smoke-derived xenobiotics. We therefore hypothesized that a NAT2 genotype would be a risk factor for periodontal disease. A total of 154 Caucasian subjects were assigned to one of two groups (1) no or mild and (2) severe periodontal disease based on radiographic (bone destruction) and clinical criteria (probing depth, attachment loss) and the number of teeth. In all subjects genotyping for mutations on NAT2 was performed by means of PCR and RFLP analysis. In the less-affected group genotyping showed a fraction of predicted slow and rapid acetylators (53.6% and 46.4%, respectively) corresponding to the normal distribution in Caucasians. Severely affected patients were predominantly slow acetylators, the odds ratios being between 2.38 and 5.02 for the NAT2-related risk depending on the outcome parameters chosen. Adjustment for age had no influence on these findings. Our data indicate that the slow acetylator phenotype is associated with a higher risk of periodontitis, especially with respect to the severity of the disease. Possible implications with respect to the risk associated with smoking are discussed.

Acetylation↗

PubMed2000

[Small breast carcinomas--less axillary surgery?].

In view of introducing less invasive or selective axillary procedures for small breast cancers we investigated our own pT1 tumor patients. The incidence of pT1 carcinoma, the nodal involvement of pT1a, b and c, the axillary relapse and the overall survival were analyzed. From 1983 till 1997 185 consecutive patients have been treated for breast cancers with a diameter of < or = 20 mm. The survival data after Kaplan-Meier are based on a cohort of 117 patients with a median follow up of at least seven years. There were seven patients with a pT1a carcinoma, 30 with a pT1b and 148 with pT1c carcinoma. On an average 16 axillary lymph nodes were counted by the pathologists. The axillary involvement clearly depends on the size of the primary tumor: no nodal involvement in patients with pT1a carcinoma, 10% in patients with pT1b carcinoma and 30% in patients with pT1c carcinoma. Not one single axillary relapse was detected after this follow up time. The overall ten years survival for patients with pT1a was 100%, 91% for pT1b, but only 74% for pT1c carcinoma. Screening mammography is expected to detect more small breast cancers in pN0 stage. Risks and benefits of axillary dissection have to be carefully evaluated. Axillary involvement of small breast cancers is rare. Only a minority of patients will benefit from routine axillary lymphadenectomy, while the majority runs the risk of complications. The sentinel lymph node (SLN) procedure offers a selective approach to this dilemma.

Adult↗

PubMed2000

[Significance of endoscopic axillary dissection in invasive breast carcinoma after introduction of the "sentinel lymph node" method].

UNLABELLED: Axillary clearance provides prognostic information, determines adjuvant therapy and reduces axillary recurrences. However significant morbidity may follow axillary dissection. Patients with small tumors (pT1a-c) may benefit from new less invasive (endoscopic lymph node dissection) or more selective (sentinel lymph node biopsy) axillary procedures which recently have been introduced. In this prospective study the axilloscopic approach was evaluated. PATIENTS AND METHODS: 55 clinically node negative patients (mean age: 60 years [30-86]) had endoscopic axillary surgery by one single surgeon (1.1996-6.1998). After axillary liposuction individual lymph nodes (level I + II) were identified and removed under direct vision by means of a laparoscope (successful procedure in 95%; n = 52). Patients were followed every four months according to a institution based follow up protocol. Results of 51 patients (1 refused) were analyzed after a median follow up of 22 (7-37) months by self-evaluation questionnaire, interview and clinical examination (including: range of motion of the shoulder joint, circumferences of the upper extremities). RESULTS: An average of 13.3 (5-25) lymph nodes was endoscopically removed. Patients (n = 16; 31%) had involved nodes with a mean of 3.1 nodes positive per individuum. Seromas necessitated needle aspiration in 8 patients (15%). There were no hematomas and one low grade infection (2%). After a median follow up period of 22 (7-37) months no axillary relapse but one trocar site implantation metastasis (1/55, 2%) was detected and resected. No lymph edema was observed. Early range of motion of the shoulder joint was excellent. CONCLUSION: This technique allows the removal of an adequate number of lymph nodes for staging as well as for regional control. The morbidity is low and the medium-term follow-up results are promising. The atraumatic and very well tolerated endoscopic axillary dissection is being replaced by the selective sentinel lymph node procedure.

Adult↗

PubMed2000

[Validation study of the sentinel lymph node (SLN) method in invasive breast carcinoma. Personal data and review of the literature].

BACKGROUND: Axillary lymph node dissection (ALND) is an integral part in the therapy of breast cancer. Axillary lymph node involvement and tumour size are the most important prognostic factors. Restriction of ALND to level I and II (Berg) reduced high morbidity. The increasing proportion of patients with early breast cancer and negative axillary nodes led to a more selective method to avoid unnecessary ALND. The sentinel lymph node (SLN)--the first draining lymph node of a tumour--represents the status of the axilla. A negative SLN prevents from further completion ALND. PATIENTS AND METHODS: From 9/97 to 1/99 44 patients with invasive breast cancer underwent a prospective trial of lymphatic mapping with isosulfanblue and/or lymphoscintigraphy with 99m technetium-labelled human colloid. During the operation a hand-held gamma probe was used for detection. The SLN was removed selectively and examined by routine histopathology (H&E) and immunohistochemistry (IHC). ALND of level I and II was performed in all patients for correlation. RESULTS: The SLN were identified in 41 of 44 patients (93%). 2.4 SLN per patient were harvested, overall 17.6 axillary lymph nodes. Of the 41 patients, 21 patients had positive, 20 patients negative SLN. In the 20 patients with negative SLN only one patient (5%) had metastatic disease on complete dissection (negative predictive value of 95%). In 17 patients with positive axillary lymph nodes 16 were found to have positive SLN, only one SLN was negative (false negative rate of 5.9%). In two of 41 patients micrometastases were detected by IHC. Lymphoscintigraphy revealed drainage to the axilla and internal mammary nodes in two of 28 cases (7%). SUMMARY: Our validation study proves the reproducibility and reliability of the SLN procedure. A multidisciplinary approach is indispensable. The SLN procedure has the potency for becoming the selection criterion whether to perform an ALND or not. Multiple sections and IHC staining improve the detection rate of metastatic disease. Ongoing long time investigations will determine the impact on overall survival. Our own data are discussed in an extended review of the literature.

Adult↗

PubMed2000

Subgingival polishing with a teflon-coated sonic scaler insert in comparison to conventional instruments as assessed on extracted teeth. (I) Residual deposits.

BACKGROUND: Recent studies have shown that endotoxins are located on the periodontally diseased root cementum and not within it. These studies led to the suggestion that the root surface could be treated less aggressively during periodontal therapy. Thus, we designed a teflon-tubed sonic scaler insert for subgingival polishing. It was our objective to assess to which extent this new instrument is capable of removing bacterial deposits in deep pockets in comparison with conventional scaling instruments. METHOD: We compared the extent to which plaque and calculus could be removed with a curette, a conventional sonic and ultrasonic scaler insert, a Per-io-tor insert, and a teflon-tubed sonic scaler insert. 84 teeth requiring extraction had been treated with one of these instruments. After extraction, the teeth were stained with Malachite green, and the following areas were assessed: area lacking plaque and calculus, calculus, and area only covered with plaque. For statistical comparison, nonparametric analyses were carried out. RESULTS: Curettes and conventional ultrasonic and sonic-scaler inserts had more area lacking plaque and calculus (97.5%, 92.2%, 92.1%) than did the Per-io-tor (80.1%) or the teflon-coated sonic scaler insert (84.4%). A similar effectivity sequence was observed for residual soft deposits (curette: 1.9%, ultrasonic scaler: 6.1%, sonic scaler: 5.4%, teflon-coated sonic scaler: 5.1% and Per-io-tor: 9.5%). CONCLUSIONS: The Per-io-tor and the teflon-coated sonic scaler insert seem to be suitable for the removal of soft deposits on the root surface, but not for the removal of calculus.

Adolescent↗

PubMed2000

Plasma lipid and blood glucose levels in patients with destructive periodontal disease.

Hyperlipidaemia and hyperglycaemia are major risk factors for cardiovascular disease. In recent years, some evidence has been presented that periodontal disease is associated with an increased risk of cardiovascular disease. To further elucidate this association, we have studied standard blood chemistry variables known as risk markers for cardiovascular disease in periodontally diseased and healthy subjects. We have measured levels of plasma lipids and fasting blood glucose in 39 subjects with moderate periodontal disease (age 50-60 years) and compared the results with those obtained in 40 age- and sex-matched controls. Both groups were systemically healthy according to their medical history. Total cholesterol, low density lipoprotein cholesterol and triglycerides were significantly higher in periodontally diseased subjects by about 8% (p<0.03), 13% (p<0.003) and 39% (p<0.001), respectively, when compared to controls. Although subjects with diabetes were excluded from the study, we found significantly higher blood glucose levels in the patient than in the control group (85 +/- 25 versus 73 +/- 17 mg/dl; p<0.02). There was also a significantly higher frequency of pathological plasma lipid profiles in the patient than in the control group. The results indicate that hyperlipaemia and pre-diabetes may be associated with periodontal disease in systemically healthy subjects. These data do not allow us to decide, whether periodontal disease causes an increase in hyperlipaemia and in a prediabetic state or whether periodontal disease and cardiovascular disease share hyperlipidaemia and the prediabetic state as common risk factors.

Aged↗

PubMed2000

Disease progression in periodontally treated and untreated patients--a retrospective study.

BACKGROUND, AIMS: The aim of this retrospective study was to assess the effect of regular supportive periodontal treatment on disease progression in patients with moderate to advanced periodontitis. METHOD: We compared radiographic change of interdental bone level and number of teeth at 2 time points in 3 patient groups (mean age 46 years): group A, periodontally untreated patients (n= 14) who dropped out during initial therapy; group B, non-compliant patients (n=26), who discontinued supportive periodontal therapy after ca. 2 years of maintenance; group C, compliant patients (n=27), who regularly attended the maintenance program for 7 years. Periodontal treatment was performed as scaling and root planing or flap surgery in groups B and C. All 3 groups were re-examined ca. 7 years after the initial examination. RESULTS: Patients in group A lost 3.8 teeth (0.5 teeth/year), those in group B 3.2 (0.4 teeth/year), and in group C, patients lost 2.0 teeth (0.2 teeth/year). About half of the patients lost no teeth (group A 43%, B 42%, C 55%), and only 17 subjects lost more than 3. At the 2nd examination, an increase in interdental bone was found only in group C (+0.13 mm), while groups A and B lost 0.57 mm and 0.31 mm of alveolar bone level, respectively (p<0.05 group C versus A and B). CONCLUSIONS: Systematic periodontal treatment stops interdental bone loss and decreases the rate of tooth loss in most cases. Periodontal surgery without regular follow-up care cannot prevent further periodontal destruction, but it can delay it.

Alveolar Bone Loss↗

PubMed2000

Resolution of interdental inflammation with 2 different modes of plaque control.

BACKGROUND, AIMS: The aim of the study was to assess the effect on existing plaque and gingivitis of an oral hygiene regimen which utilizes triclosan/copolymer and to compare it with a regimen which uses interdental cleaning devices to control the interdental inflammation. METHOD: For this investigation, 39 subjects were recruited. They were examined for plaque and gingivitis using the criteria of Turesky modification of the Quigley-Hein index and the papillary bleeding index. Plaque and gingivitis were only scored interdentally. Following the baseline examination, the subjects were randomly assigned into 2 groups. The control group used a dentifrice identical to the test dentifrice but without triclosan/copolymer; subjects in this group were taught to brush their teeth with the modified Bass technique and were instructed to additionally use appropriate interdental cleaning devices. The test group used a dentifrice containing triclosan/copolymer (Colgate Total). They were not instructed to use interdental cleaning devices. RESULTS: Both groups were re-examined after 4 weeks, and 4 and 7 months. In both groups, plaque and gingivitis levels were modestly reduced, more pronounced in the anterior and less in the posterior teeth. CONCLUSIONS: This investigation demonstrated that a dentifrice containing triclosan in combination with a copolymer can reduce plaque and gingival inflammation to levels comparable to regular interdental cleaning.

Adult↗

PubMed2000

A study on the imaging of complex furcation forms in upper and lower molars.

BACKGROUND, AIMS: The form of the molar roots and their furcated region influence both the pathogenesis of periodontal destruction and therapeutic attempts. METHOD: Using a specially-constructed measuring device, 359 1st and 2nd molars, both upper and lower, were analysed 3-dimensionally. The parameters measured were horizontal furcation concavity, height of root trunk, degree of root taper, the distance between the root prominences adjacent to the furcation entrances and the angle of root separation. RESULTS: The mean horizontal furcation concavity in lower molars was 0.5 mm at a distance of 1 mm apical to the cemento-enamel-junction (CEJ) and 3 mm at the distance of 4 mm apical to the CEJ. The angle of root separation was between 16 degrees (lower jaw molars lingual) and 29 degrees (upper jaw molars distal). The vertical distance from root separation to CEJ averaged 3.3 mm in lower jaw molars and 4.8 mm in upper jaw molars. CONCLUSIONS: Our findings underline the variability of furcation morphology.

Anatomy, Cross-Sectional↗

PubMed2000

NY-ESO-1 tumour associated antigen is a cytoplasmic protein detectable by specific monoclonal antibodies in cell lines and clinical specimens.

NY-ESO-1 gene encodes a novel member of the cancer/testis (CT) family of human tumour-associated antigens (TAA). Specific monoclonal antibodies (mAb) have identified the corresponding gene product in lysates of tumour cell lines as a 22 kDa protein but no data are available concerning its intracellular location or distribution within neoplastic tissues. We have generated NY-ESO-1 specific mAbs recognizing the target molecule in cytospin preparations and in sections from clinical tumour specimens. These reagents identify NY-ESO-1 TAA in melanoma cell lines expressing the specific gene as a cytoplasmic protein, sharing the intracellular location of most MAGE TAA. In a series of 12 melanoma specimens, specific staining, limited to neoplastic cells, was detectable in the five cases where NY-ESO-1 gene expression was observed. In two of them over 90% of tumour cells showed evidence of positive staining. Lower percentages of positive neoplastic cells ranging between single cells and 50% were observed in the remaining tumours. These data suggest that active specific immunotherapies targeting NY-ESO-1, alone or in combination with other TAA could be of high clinical relevance in sizeable subgroups of melanoma patients.

Antibodies, Monoclonal↗

PubMed2000

Feasibility of computer-assisted recognition of different dental hard tissues.

For pattern recognition, fuzzy set theory has been proven to be highly useful. The aim of the present investigation was to combine the fuzzy set with an ultrasonic scaler, to test its suitability for automatic detection of different tooth substances. An experienced operator placed the tip of a piezoceramic ultrasonic scaler on a tooth, thereby inducing oscillations in the contact area around the ultrasonic tip. Each surface showed a characteristic oscillatory behavior in the immediate vicinity of the tip. The oscillations were then re-transmitted to the scaler tip and recorded by the measurement of variations in current and voltage. Because the ultrasonic scaler is driven by piezoceramics, it can be used as both an oscillatory excitation and a sensor system. The data were processed with Fast Fourier transformation and analyzed by means of a fuzzy pattern recognition algorithm. Re-classification of the different measurements was carried out by the experienced operator's assessment. With a combination of six features (frequencies), re-classification was correct for 99% of all surfaces. The diagnostic reliability of the system was tested by the assessment of 50 teeth for which no learning data had previously been recorded. The unknown samples were correctly classified to 100%. The excellent results of these experiments suggest promising possibilities for the implementation of new diagnostic and therapeutic instruments in periodontology practice.

Algorithms↗

PubMed1999

Root debridement of single-rooted teeth with a diamond-coated sonic scaler insert during flap surgery. A pilot study.

In our laboratory, we modified inserts of a sonic scaler to increase effectivity of root surface instrumentation during flap surgery. The present clinical study investigates whether use of this diamond-coated, thickened insert facilitates more rapid root debridement compared to hand instruments and whether clinical wound healing is influenced by the type of instrument used. In 13 patients with moderate to advanced periodontal destructions, flap surgery was carried out on single rooted teeth with probing depth of > or =6 mm. The mean amount of time saved by root debridement with the diamond-coated insert was 60% over curets. Regardless of the used instrumentation method probing depths and attachment level changes were altered and remained unchanged for 2 years after surgery. In conclusion the newly-developed, diamond-coated sonic scaler insert facilitates more rapid root debridement during flap surgery than hand instruments without disadvantageously affecting clinical healing.

Adult↗

PubMed1999

Root debridement of molars with furcation involvement using diamond-coated sonic scaler inserts during flap surgery -- a pilot study.

In our laboratory, we modified sonic scaler inserts to increase effectivity of root surface instrumentation of molars with furcation involvement during flap surgery. The working end of conventional sonic scaler inserts was thickened ellipsoidally and diamond coated. Inserts with variously angled shafts were designed in order to facilitate insertion into the furcation. A clinical, split-mouth study examined the debridement of molars with furcation involvement during flap surgery using either hand instruments or diamond-coated sonic scaler inserts with 15 patients. Average treatment time was cut by ca. 50%, using diamond-coated inserts as compared to hand instruments for root surface debridement during surgery. 2 years after surgery, the clinical parameters had not been influenced by type of instrument used.

Adult↗

PubMed1999

Langerhans cell histiocytosis of the stomach with atypical morphological features.

We report the unique case of a 52-year-old patient with atypical morphological features of gastric Langerhans cell histiocytosis. The man was admitted because of increasing upper abdominal pain and weight loss. The upper gastrointestinal endoscopy showed a submucous, hemispherical tumor of the stomach wall along the lesser curvature. The tumor was completely removed and the patient was discharged 11 days later. Two months later, he died at home. The cause of death is unknown, because the autopsy was denied by the relatives. Macroscopically, the stomach showed a 4.5 x 2.5 cm large, spherical tumor of the lesser curvature of the corpus, which infiltrated the perigastric omenta and lymph nodes, the distal pancreas and the glissonian liver capsule. The vast majority of neoplastic cells were intensely positive for S-100 and CD1a. Typical Birbeck granules could be identified in almost all cells. Cell nuclei analyzed by flow cytometry showed an aneuploid peak, a feature typically associated with malignant disease.

Cytoplasmic Granules↗