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Biomedical subjects

H Bartels

Publications and source records attributed to H Bartels.

At least 73 records · Page 4Linked to original sources
PubMed1996

Poly(DL-lactide-epsilon-caprolactone) nerve guides perform better than autologous nerve grafts.

The aim of this study was to compare the speed and quality of nerve regeneration after reconstruction using a biodegradable nerve guide or an autologous nerve graft. We evaluated nerve regeneration using light microscopy, transmission electron microscopy and morphometric analysis. Nerve regeneration across a short nerve gap, after reconstruction using a biodegradable nerve guide, is faster and qualitatively better, when compared with nerve reconstruction using an autologous nerve graft. Therefore, we conclude that in the case of a short nerve gap (1 cm), reconstruction should be carried out using a biodegradable nerve guide constructed of a copolymer of DL-lactide and epsilon-caprolactone.

Analysis of Variance↗
PubMed1996

In-vivo evaluation of random donor platelet concentrates from pooled buffy coats.

Random-donor platelet concentrates (PC) prepared from pooled buffy coats have recently been described as an alternative method for platelet preparation. We evaluated such PCs in the clinical setting compared with a standard PC from platelet apheresis. PCs were prepared either from pools of buffy coats (BC-PC) or from single donors (SD-PC) with the cell separator CS-3000 plus. PCs were stored for up to 5 days before transfusion. We compared fresh PC (day 1) with stored (day 2-3) and long-stored PC (day 4-5). For analysis, platelet increment in the recipient was determined immediately and 16-22 h (mean 20 h) after transfusion, corrected for total body area and transfused platelets (CCI). A total of 316 PCs were administered to 36 thrombocytopenic patients suffering from various hematological disorders. Patients with detectable HLA or platelet-specific antibodies or splenomegaly were excluded from the study. Mean platelet content of the PC was 262 x 10(9) for BC-PC and 251 x 10(9) for SD-PC. The 20-h CCI after transfusion of fresh PC was slightly higher with BC-PC than with SD-PC (14.5 versus 11.9; p = 0.19), but values did not differ significantly between the two types of PC on any day of storage. For BC-PC, 20-h CCI decreased with further storage by 30% (10.2; p = 0.02). For SD-PC a decrease by 9% was not significant. In conclusion, platelet concentrates prepared from pools of buffy coats showed excellent transfusion results when administered fresh, but storage decreased the CCI by 30%. No significant difference from PCs from plateletpheresis was observed on any day of storage. Both types of platelet concentrates were capable of sufficient platelet increment even when stored for up to 5 days.

Adult↗
PubMed1996

Multihandicapped blind and partially sighted children in south Germany. II: Aetiology and pathogenesis.

The results of a classification of the aetiology of visual impairment and mental retardation in a series of 239 multihandicapped blind and partially sighted children are reported. These children had been born between 1981 and 1987 and were examined in a population-based study in South Germany. There was marked aetiological heterogeneity. Most prominent were causes related to the perinatal period and late gestation which were found in 41% of the children. Among these, lesions of the visual pathways in preterm children were especially frequent and could be explained by periventricular leukomalacia in a large proportion. The distribution of the major aetiologic groups is different from populations with isolated mental retardation and populations with isolated visual impairment but similar to a Swedish population with spastic quadriplegia. The implications for the prevention of severe multiple impairments in children are discussed.

Age Distribution↗
PubMed1996

Changes in the apical surface of chloride cells following acclimation of lampreys to seawater.

Scanning electron microscopy (SEM) was used to study the changes that occur in the morphological relationships between chloride and pavement cells in the gills during acclimation of young adult lampreys to seawater. Because chloride cells are located predominantly between lamellae and are thus obscured from view, the lamellae were removed with the use of a micromanipulator installed in a SEM. In gills of animals maintained in river water, chloride cells could then be seen to be dislike and typically to form single rows between successive lamellae. After acclimation to seawater, the apical surfaces of chloride cells lose their microvilli and change in shape from small circles to rectangles that extend the full width between successive lamellae. These changes result in an increase in the length of the paracellular pathway between chloride cells. Previous work has shown that the number of strands of the zonulae occludentes sealing this pathway declines under these conditions. This presumably leads to an increase in paracellular permeability of the gill epithelium, thereby providing the low-resistance paracellular shunt required for the passive movement of sodium into the environment during osmoregulation in seawater. The above changes are reversed by transfer of lampreys downward to 10% seawater.

Acclimatization↗
PubMed1996

Significance of cytogenetic findings for the clinical outcome in patients with T-cell lymphoma of angioimmunoblastic lymphadenopathy type.

PURPOSE: The aim of this study was to evaluate the significance of cytogenetic findings for the clinical outcome of patients with Angioimmunoblastic Lymphadenopathy (AILD)-Type T-cell lymphoma. MATERIALS AND METHODS: In a retrospective analysis, the cytogenetic findings of 50 patients with AILD-type T-cell lymphoma were correlated with the frequency of spontaneous and therapy-induced remissions and with survival using the statistical methods of Kaplan and Meier and the model of Cox for multivariate analysis. Treatment was not uniform because the patients were treated in different hospitals during a period of 8 years and because a standard therapy has not yet been established. RESULTS: The following cytogenetic findings were associated with a significantly lower incidence of therapy-induced remissions and a significantly shorter survival duration: presence of aberrant metaphases in unstimulated cultures (P = .04 for both parameters); clones with an additional X chromosome (P = .0001 and P = .03, respectively); structural aberrations of the short arm of chromosome 1, preferentially involving 1p31-32 (P < .001 and P = .04, respectively); and complex aberrant clones with more than four aberrations (P = .0003 and P = .005, respectively). Multivariate analysis showed that these cytogenetic findings had a significant influence on survival, but therapy modalities did not. Only the presence of complex aberrant clones was an independent prognostic factor. Trisomy 3 had no effect on survival, but patients without trisomy 5 (P = .08) tended to live longer. CONCLUSION: This is the first study that seems to indicate that cytogenetic findings have prognostic significance in AILD-type T-cell lymphoma. These results must be proven in prospective studies of homogeneously treated patients.

Adult↗
PubMed1996

Epirubicin and ifosfamide in metastatic breast cancer.

In a randomized, phase II trial, we evaluated the effectiveness of continued chemotherapy with epirubicin/ ifosfamide versus unmaintained treatment interruption in advanced metastatic breast cancer. Three hundred fifty-seven patients were enrolled and 331 were evaluable for response. Complete response was achieved in 25 patients (8%) and partial response in 121 patients (37%). Pretreatment status correlated significantly with response (complete and partial response). While 54% of unpretreated patients responded, only 42% of the patients responded who had been pretreated with adjuvant chemotherapy and 33% who had been pretreated in the metastatic stage of disease; 69 patients (21%) had disease progression. Of 11 patients pretreated in both the adjuvant and metastatic setting, only two responded. Toxicity of treatment was mild, with leukopenia being the treatment-limiting factor. Thrombocyte levels were not altered significantly by treatment. Thus, there seems to be room for dose escalation using granulocyte colony-stimulating factor. There was no considerable cardiotoxicity, central nervous system toxicity, or cystitis observed. The low rate of cardiotoxicity appeared to be related to dose fractionation of epirubicin. After randomization of patients to treatment interruption versus continuation of chemotherapy, a longer relapse-free survival was observed for patients who continued chemotherapy (mean relapse-free survival, 2+ months); however, this did not translate into prolonged survival. The cumulative scores of toxicity and quality of life parameters showed increasing superiority for treatment interruption. Therefore, a strategy of treatment until maximum response and subsequent treatment interruption seems to be superior to treatment continuation.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

[Preoperative risk and postoperative follow-up in surgery of esophageal carcinoma].

The risk involved in esophagectomy in patients with esophageal cancer is related to the general preoperative status of the patient and to the cardiac, pulmonary and hepatic functions. This can be objectively assessed prior to surgery and quantified by a composite risk score. Strict inclusion of the risk score in the preoperative decision-making process resulted in a marked decrease in postoperative mortality at our institution to 1.8%.

Cause of Death↗
PubMed1995

Large-cell anaplastic lymphoma-specific translocation (t[2;5] [p23;q35]) in Hodgkin's disease: indication of a common pathogenesis?

Chromosomal aberrations are characteristic and specific events; the detection of chromosomal abnormalities often provides information on diagnosis and prognosis of disease. Some patients with large-cell anaplastic lymphoma (Ki 1 lymphoma) have the translocation t(2;5) (p23; q35), involving a possible growth-regulating tyrosine kinase. We found this translocation in 11 patients with Hodgkin's disease of nodular sclerosis and mixed-cellularity types. This finding has implications for the understanding of the relation between large-cell anaplastic lymphoma and Hodgkin's disease, diseases with morphological and immunophenotypical similarities. Study of this translocation may help understanding of the origins of cancer and cancer growth. It also allows a more precise definition of Hodgkin's disease and may be used as an indicator for clonality--which has long been sought.

Actins↗
PubMed1995

Ultrastructure and protein transport of M cells in the rabbit cecal patch.

BACKGROUND: The gut-associated lymphoid tissue of the rabbit cecum includes a single lymphoid patch located close to the ileocecal orifice. Vimentin immunoreactivity, which can now be regarded as a marker for M cells in rabbits, has identified a subpopulation of epithelial cells as M cells in the domes of this patch. The aim of the present study was to demonstrate that these M cells are capable of antigen transport and to characterize their ultrastructure. METHODS: M cells of the rabbit cecal lymphoid patch were studied by scanning, thin section, and freeze-fracture electron microscopy. The transcytosis across these M cells was investigated using horseradish peroxidase as a soluble tracer protein. RESULTS: The M cells were concentrated at the flanks of the domes and had long, thick, branched microvilli, a well-developed terminal web, and a deep invagination of their apical membrane. Numerous small vesicles lay beneath the terminal web in close vicinity to the base of the invagination. These vesicles transported the luminally applied horseradish peroxidase through the M cells. In contrast to adjacent enterocytes, the glycocalyx of M cells was thin, stub-like, and had very few glycocalyceal bodies. Bacteria adhered to the surface of M cells and were also found in the apical invagination. CONCLUSIONS: The M cells of the rabbit cecal lymphoid patch differ from those of Peyer's patches of the small intestine in their ultrastructure and route of antigen transport. These differences might be related to the situations resulting from differences in the microbial populations at these locations.

Animals↗
PubMed1995

Relationships between endothelial cells, pericytes, and osteoblasts during bone formation in the sheep femur following implantation of tricalciumphosphate-ceramic.

BACKGROUND: The origin of osteoblasts is still controversial. Whereas several authors consider the stromal fibroblast of the bone marrow as the osteoprogenitor cell, others propose that the osteoblasts can be derived from the "capillary system." The present study examines the replacement of tricalciumphosphate (TCP)-ceramic implanted into an artificial bone defect by newly formed bone. The results support the hypothesis that osteogenic cells can be derived from invading blood vessels. METHODS: The spongiosa of the trochanter major of sheep was removed and the defect was filled with TCP-ceramic. Two months after surgery the ceramic implants together with the surrounding bone were removed and processed for transmission electron microscopy. Serial ultrathin sections of three newly formed osteons were examined. RESULTS: The osteons contain one or two small sprouting capillaries, a peripheral layer of osteoblasts, and in between, a network of glycogen-rich cells. Some of the glycogen-rich cells are completely or partly surrounded by the endothelial basal lamina and are thereby characterized as pericytes. Weibel-Palade bodies, which are considered to be a marker of endothelial cells, were occasionally observed in glycogen-rich pericytes. CONCLUSIONS: Since pericytes differentiate into osteoblasts under in vivo and in vitro conditions, and have thus been regarded as osteoprogenitor cells, the presence of Weibel-Palade bodies in these cells suggest that osteogenic cells can be derived from endothelial cells.

Animals↗
PubMed1995

The suitability of a monofunctional reagent of an undecagold cluster for phasing data collected from the large ribosomal subunits from Bacillus stearothermophilus.

An electron density map of the large ribosomal subunit from Bacillus stearothermophilus was obtained at 26 A resolution by single isomorphous replacement (SIR) from a derivative formed by specific quantitative labeling with a dense undecagold cluster. For derivatization, a monofunctional reagent of this cluster was bound to a sulfhydryl group of a purified ribosomal protein, which was in turn reconstituted with core particles of a mutant lacking this protein. The native, mutated, and derivatized 50S ribosomal subunits crystallize under the same conditions in the same space group. Under favorable conditions, crystals of the derivatized subunit proved to be isomorphous with the native ones, whereas the crystals of the mutant may have somewhat different packing. After resolving the SIR phase ambiguity by solvent flattening, the electron density shows a packing that is consistent with the noncrystallographic symmetry found by Patterson searches as well as with the motif observed in electron micrographs of thin sections of the crystals. These studies established that phase information can be obtained from heavy metal clusters, even when the crystals under investigation are unstable and weakly diffracting. These results encouraged further effort at the construction of specifically derivatized crystals from other ribosomal particles that diffract to higher resolution.

Crystallography, X-Ray↗
PubMed1995

Reinforced poly(L-lactic acid) fibres as suture material.

In this study, reinforced poly(L-lactic acid) (PLLA) fibers made by a dry-spinning/hot-drawing process were evaluated for use as a suture. The initial tensile strength of the PLLA fibers was lower than the initial tensile strength of the commercially available sutures: PDS, Vicryl, silk, and Ethilon. However, after 12 weeks immersion in a phosphate saline buffer at 37 degrees C, PDS sutures have lower tensile strength than PLLA sutures and the tensile strength of Vicryl was unmeasurable because of fragmentation. Initially, PLLA fibers disintegrated into fibrils during degradation triggering an inflammatory response comparable to degradable multifilament sutures. However, the intensity of the inflammatory response against the PLLA fibers decreased and after 80 weeks implantation in the muscle layer of the abdominal wall of rats it was comparable to the one against Ethilon. The inflammatory response against Ethilon, which is considered to be nondegradable, increased in the same period, probably due to the change in shape. In practice, the handling characteristics of PLLA sutures are superior to the monofilament sutures like PDS and Ethilon and comparable with the multifilament sutures like Vicryl and silk. The knot security of PLLA sutures are expected to be better than the knot security of the monofilament sutures, but this remains to be investigated. It is concluded that dry-spun/hot-drawn (reinforced) PLLA fibers have the potential for use as long-term degradable suture material.

Animals↗
PubMed1995

Structural organization and epithelial cells types of the intestinal diverticula (protopancreas) of ammocoetes of southern hemisphere lampreys: functional and phylogenetic implications.

Larvae of the two southern hemisphere lamprey genera, Mordacia and Geotria, possess one and two intestinal diverticula, respectively, each originating at the oesophageal-intestinal junction. These diverticula comprise an inner layer of simple columnar epithelium composed solely of zymogen and mucous cells, a middle layer consisting mainly of a blood sinus, and an outer serosa layer covered by a simple squamous epithelium (mesothelium). The inner surface is highly folded only in Mordacia. The secretion of mucus probably protects the epithelium from the effects of digestive enzymes secreted by the zymogen cells and/or bile, which enters the diverticulum at its tip. Unlike the situation in southern hemisphere lampreys, the zymogen cells of the larvae of holarctic lampreys are located in the anterior intestine, a condition considered to be "primitive". It is thus proposed that intestinal diverticula were developed during the evolution of southern hemisphere lampreys. The relocation of zymogen cells in the diverticula increases the area for these cells, and thus the capacity for the synthesis and secretion of digestive enzymes, particularly in Mordacia where the inner surface is folded.

Animals↗
PubMed1995

Cytogenetic findings in 179 patients with myelodysplastic syndromes.

Cytogenetic analyses were performed on 266 bone marrow and peripheral blood samples from 179 patients with myelodysplastic syndromes (MDS). According to the FAB classification, 42 patients presented with RA, 18 with RARS, 37 with RAEB, 22 with CMML, and 29 with RAEB-T. Nine patients showed a secondary MDS (S MDS). FAB classification was not available for 22 patients. Clonal karyotype anomalies were found in 92 patients (51.4%). Complex chromosome abnormalities occurred in 17 (18.5%) of them. An evolution of the karyotype was detected in 16 cases (17.4%). Cytogenetically independent cells or cell clones were found in eight patients. Nonclonal chromosome abnormalities were uncovered in 29 (16.2%) of the 179 MDS patients. Consecutive studies were performed in 48 patients and revealed a good correlation of initial karyotype and clinical course. The most frequent single anomalies were 5q- in 29 (31.5%), -7 in 22 (23.9%), trisomy 1q in 14 (15.2%), and +8 in 13 (14.1%) of 92 patients respectively. Our cytogenetic findings are presented in detail and discussed in relation to patients' age, morphological classification, clinical course, and prognostic impact. The contribution of cytogenetic findings to the delineation of multistep pathogenesis of MDS with special emphasis to karyotype instability is demonstrated.

Adult↗
PubMed1995

A comparison of polychemotherapy and melphalan/prednisone for primary remission induction, and interferon-alpha for maintenance treatment, in multiple myeloma. A prospective trial of the German Myeloma Treatment Group.

406 untreated multiple myeloma patients of stage I (n = 54), II (n = 148) and III (n = 204) were enrolled in the trial. 51/54 stage I and 60/148 stage II patients were asymptomatic and followed without treatment until disease progression (progression free survival: 60% after 4 years for stage I versus 50% after 1 year for stage II). Symptomatic patients of stage I (n = 3/54) and II (n = 88/148) presenting with tumour progression, received melphalan 15 mg/m2 intravenously (i.v.) and prednisone 60 mg/m2 oral days 1-4 (MP). Stage II disease remission rate was 59%, and 50% tumour related survival (TRS) was 59 months. Stage III patients were randomised to receive MP or VBAMDex (vincristine/BCNU/doxorubicin/melphalan/dexamethasone) treatment. 43% of MP treated patients responded compared with 64% of the VBAMDex group. 50% TRS was 36 months in both groups without a detectable difference. 117 responders of stage II and III with stable disease were randomised to receive either IFN-alpha (5 x 10(6) IU, subcutaneous (S.C.) 3 times per week) or no maintenance treatment. The relapse rate in both groups was 50% after 13 months. No survival benefit for IFN alpha treated patients was observed (50% TRS: 45 months).

Aged↗
PubMed1995

Prognostic factors of resected adenocarcinoma of the esophagus.

BACKGROUND: The main purpose of this study was to determine prognostic factors in patients with surgical treatment of adenocarcinoma of the esophagus. METHODS: Within a 12.5-year period, esophageal adenocarcinoma was resected in 165 patients by radical transhiatal esophagectomy (n = 134) or transthoracic en bloc esophagectomy (n = 31). Tumors were analyzed according to the 1992 UICC classification with respect to pTNM stage, residual tumor (R) status, grading, and ratio of infiltrated to resected lymph nodes (lymph node ratio); both univariate and multivariate analysis of prognostic factors were performed. RESULTS: The 30-day mortality rate was 6.1%. A complete removal of the tumor was achieved in 83% of the patients. Lymph node metastases were not detected in mucosal cancer (pT1a) but were detected in 18% of submucosal cancer (pT1b), 77% of pT2, 83% of pT3, and 96% of pT4. The overall 5-year survival rate was 34%; for patients without postoperative residual tumor (R0) it was 41%, and for those without lymph node metastases (pN0, R0) 63%. The 5-year survival rate for patients (pN1) with less than 30% invaded lymph nodes was 45%, compared with 0% for more than 30% invaded nodes. Independent prognostic factors for R0 resected patients excluding postoperative fatal outcome were pT and lymph node ratio. CONCLUSIONS: Long-term survival after resection of esophageal adenocarcinoma is mainly associated with complete tumor removal, limited esophageal wall penetration, and ratio of infiltrated to removed lymph nodes of less than 0.3.

Adenocarcinoma↗
PubMed1995

[Extremely severe complication during ESWL caused by unsuspected asymptomatic pheochromocytoma].

In 0.1% the pheochromocytoma is the reason of a systemic hypertension. The symptoms of a persistent or paroxysmal hypertension with headache, excessive sweating and palpitations lead in 90% to the diagnosis pheochromocytoma. Very rarely a patient with pheochromocytoma may be asymptomatic. We introduce a 68-year-old man whose pheochromocytoma primarily rose up while ESWL and furthermore in anaesthesia. The problems to determine the diagnosis will be scrutinized as following.

Adenocarcinoma↗