Technische Anwendungen der Bruchmechanik auf dünnwandige Bauteile

Bauteilähnliche Proben zum Ermitteln von Kennwerten für das zahlenmäßige Abschätzen der Auslösungs- und Auffangbedingungen spröder Brüche in ungeschweißten und geschweißten dünnwandigen Bauteilen. Einfluß unterschiedlicher Fehler, besonders beim Herstellen der Schweißverbindungen. Auswirkung des Spannungsarmglühens. Bedeutung geringer Kaltverformungsgrade. Bewerten von Krümmungen. Einfluß der Blechdicke. Maßnahmen zum Auffangen spröder Brüche. Abschätzen des Bruchverhaltens aufgrund von Versuchsergebnissen an Kleinproben.     

Assimilation rates of different particulate foods for Simulium verecundum (Diptera: Simuliidae)

Particulate food assimilation rates for larvae of Simulium verecundum Stone & Jamnback were studied using three radiolabelled particulate foods: Navicula pelliculosa Bréb. ex Kütz.) Hilse (a diatom), Scenedesmus quadricauda (Turp.) Bréb. (a green alga), and field-collected, size-fractionated (< 3.0 microns) heterotrophic bacterioplankton. Assimilation was determined by radiolabelling the microorganisms followed by a 5-h laboratory feeding of each food to fifth- to seventh-instar S. verecundum. The bacterioplankton provided the highest assimilation efficiency (27.8%). N. pelliculosa produced higher assimilation efficiency estimates (19.5%) than did S. quadricauda (4.0%). The relationship between black fly abundance and the availability of quickly assimilated food is discussed.     

Die eisernen Pfahlschuhe der Römerbrücke in Trier

Verbundwerkstoff aus Eisen und Holz beim Bau einer Brücke in Trier durch die Römer. Hohe Korrosionsbeständigkeit des Pfahlschuheisens im Flußbett der Mosel. Analytische und metallkundliche Untersuchung der Pfahlschuhlaschen. Bestimmung der Kerbschlagzähigkeit und der Übergangstemperatur des römerzeitlichen Eisenwerkstoffs. Prüfung der heutigen Korrosionsbeständigkeit der Pfahlschuhe in Industrielufl.     

Strategies for expressing human antibody repertoires in transgenic mice

Repertoires of human antibodies can be created in transgenic mice carrying human immunoglobulin-gene loci in germline configuration. These 'transloci', introduced either as miniloci or as almost locus-sized regions, undergo rearrangement and hypermutation in mouse lymphoid tissue. Here, Marianne Brüggemann and Michael Neuberger review the use of such mice for raising antigen-specific human monoclonal antibodies, as well as their exploitation for studying regulatory aspects of antibody repertoire formation.     

Das Verformungsverhalten im Zugversuch des Stahles Ck45 bei tiefen Temperaturen

An glatten und verschieden gekerbten Proben aus Ck45 wurden im Temperaturbereich 100 K ≦ T ≦ 295 K Zugversuche mit konstanter Querhauptgeschwindigkeit durchgeführt, wobei in Abhängigkeit von den Zugkräften sowohl die Probenverlängerungen als auch die Kerbgrunddehnungen bestimmt wurden. Während die aus Nennspannungs, Probenverlängerungs-Diagrammen ermittelten Werkstoffwiderstandsgrößen keine Aussagen zum Deformationsverhalten des Kerbgrundes zulassen, können anhand der Nennspannungs, Kerbgrunddehnungs-Diagramme die temperatur- und formzahlabhängigen Kerbstreckgrenzen beurteilt werden. Unter Berücksichtigung des im Kerbgrund vorliegenden zweiachsigen Spannungszustandes beschreibt bei den gewählten Versuchstemperaturen die Gestaltänderungsenergiehypothese die Abhängigkeit der Kerbstreckgrenze von der Formzahl qualitativ richtig. Die auftretenden Unterschiede zwischen rechnerischer Abschätzung und Experiment werden erörtert. Durch Verformungsmessungen und durch rasterelektronenmikroskopische Bruchflächenuntersuchungen wird nachgewiesen, daß auch den bei Temperaturen von 100 K auftretenden makroskopisch spröden Brüchen der Kerbstäbe merkliche plastische Verformungen vorausgehen. Die Kerbzugfestigkeit nimmt in Abhängigkeit von der Formzahl bei allen Temperaturen zunächst mit der Formzahl zu und fällt nach Erreichen eines Maximalwertes wieder ab.     

Endometrioid adenoma (polypoid endometriosis) of the omentum maius

Endometrioid adenoma (polypoid endometriosis) of the omentum maius in an 89-year old female is reported. The tumor measured 1 cm in diameter and consisted of resting or weakly proliferating, partially macrocystic endometrial glands, encapsulated by delicate fibrous connective tissue. Immunohistochemically, glandular and stromal cells expressed estrogen receptor strongly, progesterone receptor weakly and CA 125 only weakly in a few glands. This is another, but rare example of the capacity of the omentum maius to develop tumors of the Müllerian variety.     

Synergistic mechanism between Brønsted acid site and active cerium species in hydride transfer reaction over CeY zeolites

In this study, cyclohexene was used as a representative of olefin and catalyzed by CeY zeolites in a fixed-bed reactor under mild conditions, and the influence of Ce species in hydride transfer reaction over CeY zeolites was evaluated. CeY zeolites show more excellent hydride transfer properties than HY zeolite. Based on the results of almost identical Brønsted acid properties but not the product distributions for 0.075CeY and 0.075CeY(DC) samples, it should be suggested that the Brønsted acid strength and density are not the deciding factors to the hydride transfer reaction. A unique band at 1442 cm⁻¹ in situ FTIR spectroscopy spectra are assigned to pyridine complexes bonded to a class of active Ce species that could reversibly migrate from the core of SOD cages to its 6-rings mouth towards the supercages. These results provide valuable information that these active Ce species should play a synergistic role with the Brønsted acid sites in enhancing the hydride transfer reaction with a bimolecular mechanism over CeY zeolites.     

Homicide in the United States, 1951-1990: synchronous age-specific rate changes in adult men

We report a man with pre-Cushing's syndrome due to ACTH-independent bilateral macronodular adrenocortical hyperplasia. Plasma ACTH was low and urinary 17-OHCS was not suppressed by a high dose of dexamethasone (8 mg), but plasma cortisol was responsive to exogenous ACTH. The adrenal glands were enlarged and contained multiple nodules composed of large clear cells and small compact cells. The steroid levels in the adrenal glands were lower than those in overt Cushing's syndrome due to the adrenocortical adenoma. This suggests that the tumor produces insufficient amounts of active hormones to have a clinical effect.     

Chronic urticaria and intermittent anaphylaxis. Reactions to lophendylate

In a case of chronic, severe urticaria and intermittent episodes of anaphylaxis due to an iophendylate injection (Pantopaque) given in the course of myelography, almost complete relief was obtained from the removal of approximately 8 ml of residual iophendylate from the spinal canal. Data obtained from direct skin testing, Prausnitz-Küstner testing, peptide inhibition of Prausnitz-Küstner testing, and IgE levels quantitated before and after removal of iophendylate indicate that these symptoms were mediated via an IgE anti-iophendylate reaction.     

Histopathologic spectrum of vaginal adenosis and related changes in stilbestrol-exposed females

A total of 98 colposcopically directed biopsies were obtained from the vagina, cervix, and cervicovaginal ridge (hood) of 80 young women believed to have had intrauterine exposure to stilbestrol (DES). Specific investigation of the patient's medical records corroborated the history of maternal stilbestrol administration in 36 patients (45%), while in the remainder the drug history was regarded as presumptive since medical records were unavailable for review. The findings did not differ significantly in those biopsies taken from patients with confirmed or presumptive drug histories. Histologic evidence of vaginal adenosis was detected in vaginal biopsies from 43 patients. In 30 cases (70%) benign Müllerian-type glandular epithelium was in the superficial vaginal wall, residing on the mucosal surface and/or in the lamina propria. The glandular epithelium predominantly was of endocervical type, but in six instances it resembled endometrial or fallopian tubal epithelium. The glands were accompanied by varying degrees of squamous metaplasia in 22 cases. When extensive the metaplasia produced transformation zones similar to those seen in the normal cervix. Vaginal biopsies of adenosis from the other 13 patients (30%) revealed squamous metaplasia without demonstrable glands due to complete transformation of all antecedent glandular epithelium by squamous metaplasia. Our studies indicate that squamous metaplasia is a component of major importance in the natural history of adenosis and that the concept of adenosis should be broadened to include those examples comprised exclusively of metaplastic epithelium. In such examples metaplasia is identified by the immaturity and poor glycogenation of the squamous cells and their accompanying squamous pegs which often contain residual gland openings or squamous "eddies." Similar findings were present in biopsies of seven cervicovaginal ridges and in cervical biopsies from 37 patients, except for the absence of endometrial or tubal type glands in the latter site. Although no adenocarcinomas were detected, six patients had squamous dysplasia of the vagina and/or cervix. In no case were premalignant or dysplastic changes of glandular cells found. Our findings support the thesis that stilbestrol-associated adenosis represents anomalous embryologic localization of the original squamocolumnar junction in the vagina rather than in the cervix. It is closely related to so-called cervical "erosions." The development of squamous metaplasia accounts for modifications in the clinical and histologic appearances by producing transformation zones which then may be subject to the same oncogenic stimuli for squamous neoplasia as are their counterparts in the cervix.     

Surgical significance of supernumerary parathyroid glands in renal hyperparathyroidism

In secondary hyperparathyroidism (2HPT) fundamentally all parathyroid glands, including supernumerary glands, become hyperplastic, and stimulation of parathyroid glands continues after parathyroidectomy (PTx). Therefore supernumerary glands have special significance during surgery for 2HPT, whether persistent or recurrent HPT. In the present study 570 patients underwent initial total PTx with a forearm autograft. The frequency, type, location, histopathology, and clinical significance of the supernumerary glands were evaluated. At the initial operation 90 supernumerary glands were removed from 82 to 570 patients (14.4%); 12 patients (2.1%) required extirpation of supernumerary glands for persistent/recurrent HPT. Altogether 104 supernumerary glands were identified at operation in 94 of the 570 patients (16.5%). Among these 104 glands, 25 (24.0%) were of the rudimentary, or split, type and 79 (76.0%) of the proper type. Supernumerary glands were most frequently identified in the thymic tongue (53/104, 51.0%); 32 (60.4%) of these 53 glands were identified only microscopically. In 6 of the 570 cases (1.1%), reoperation was required for persistent HPT due to supernumerary glands located in the mediastinum, and 6 patients underwent neck reexploration for recurrence. Histopathologically, 61 of 104 (58.7%) supernumerary glands, including 36 glands recognized only microscopically, showed diffuse hyperplasia, and 43 (41.3%) displayed nodular hyperplasia. Residual small supernumerary glands with diffuse hyperplasia have the potential to be transformed to nodular hyperplasia during long-term hemodialysis. Therefore all parathyroid glands including supernumerary glands should, if possible, be removed at the initial operation. Routine removal of the thymic tongue and careful examination of the regions surrounding the lower poles of the thyroid, especially on the left side, are important steps in the surgical treatment.     

Role of glutamate receptor subtypes in the differential release of somatostatin, neuropeptide Y, and substance P in primary serum-free cultures of striatal neurons

The objective of this study was to determine if hyperthyroidism affects the responses of Müller's muscle to alpha-1 adrenoceptor agonists and consequently, if these responses might explain thyroid eyelid retraction. Sprague-Dawley adult rats (n = 37) were divided into control and treated groups and given either placebo or intraperitoneal triiodothyronine (250 micrograms/kg/d) for 1, 2, or 3 weeks. A suture was passed through their upper eyelid and connected to a force transducer that measured Müller's muscle contractions. Responses to phenylephrine (0.015-0.61 mmol) were compared with respect to peak amplitude and 50% duration of action. Mean maximum force values [+/-1 standard error of the mean (SEM)] in response to phenylephrine were 1.254 +/- 0.071 gr for controls and 0.963 +/- 0.062 gr for thyroid-treated subjects (p = 0.005). Mean 50% duration of response values (+/-1 SEM) were 9.143 +/- 1.108 min for controls and 5.763 +/- 0.973 min for thyroid-treated subjects (p = 0.014). Hyperthyroid rats had a significantly lower Müller's muscle response amplitude than control rats; however, duration of response was not significantly different between the groups. We believe that hyperthyroidism caused intrinsic changes in Müller's muscle that resulted in eyelid retraction. Based on hypotheses discussed in this article, we expect that further studies will localize these changes to the thyroid hormone receptor on Müller's muscle or calcium-triggered intracellular second messengers. Clinical significance would then be the ability to treat hyperthyroid eyelid retraction with drugs. This study provides the first evidence of functional impairment of Müller's muscle due to hyperthyroidism in an animal model.     

Fine needle aspiration cytology of malignant chondroid syringoma: a case report

BACKGROUND: Chondroid syringoma, a tumor of the eccrine glands, was previously called mixed tumor of skin as it has both mesenchymal and epithelial elements. Malignancy in this tumor is extremely rare. Although there are a few reports describing the cytomorphologic features of chondroid syringoma, the cytologic findings of its malignant counterpart have not been described. CASE: A 40-year-old female presented with a recurrent swelling on the scalp of one year's duration. Fine needle aspiration yielded blood-mixed gelatinous material. May-Grünwald-Giemsastained smears showed epithelial cells arranged in cordlike structures and ill-formed glands against a myxomatous background. The epithelial cells had scanty cytoplasm and markedly pleomorphic nuclei with prominent nucleoli. A few cells in the stroma had a halo around them and a resemblance to cartilage cells. A preoperative diagnosis of malignant chondroid syringoma was made. The tumor was excised, and the cytologic diagnosis was confirmed on histopathology. CONCLUSION: Cytomorphologic features of a rare case of malignant chondroid syringoma are reported for the first time. The presence of malignant epithelial cells against a myxoid background with a few chondroid foci helped in making a correct preoperative diagnosis.     

Nonadenomatous thymic unencapsulated parathyroid tissue as a cause of persistent primary hyperparathyroidism

Primary hyperparathyroidism may be caused by ectopic intrathymic parathyroid adenomas or hyperplastic parathyroid glands. The association of the ectopic inferior parathyroid glands and the thymus is due to their common embryologic origin from the third pharyngeal pouch. We report a case of primary hyperparathyroidism due to an unusual pathologic parathyroid gland formation: nonadenomatous thymic unencapsulated parathyroid tissue. Two unsuccessful neck exploration revealed only two normal parathyroid glands within the cervical area. Radiologic imaging studies failed to localize an ectopic parathyroid adenoma. Mediastinal exploration and thymectomy showed one small focus of unencapsulated hypercellular parathyroid tissue expanding peripherally along the septa of thymic adipose tissue. The hyperparathyroidism resolved with the surgical procedure.     

Accuracy of 94 anaesthetic agent vaporizers in clinical use

Using the Brüel & Kjaer Anaesthetic Gas Monitor type 1304, we have monitored the output of 94 anaesthetic agent vaporizers (Fluotec 3:58, Enfluratec 3:24, Isotec 3:12), in seven departments of anaesthesia, at different dial settings and flow rates. The range of output, for one type of vaporizer and dial setting (flow: 6 litre min-1) was largest with the Fluotec 3 (0.85-1.55% when dial set to 1%) and smallest with the Isotec 3 (0.85-1.15% when dial set to 1%). In determining the number of vaporizers with unacceptable inaccuracy, we applied acceptance limits of +/- 15% relative on each vaporizer and each dial setting. Using a flow of oxygen 6 litre min-1 17% of Fluotec 3.8% of Isotec 3 and 71% of Enfluratec 3 vaporizers had outputs outside those limits. Even when some specific conditions (vaporizers giving output beyond the limits at any two or more dial settings; output beyond the limits in the clinically relevant range (0.5-2%)) were added, a substantial number of vaporizers did not perform within the limits. We found a significantly greater accuracy of the vaporizers after 3-monthly calibration checks (P < 0.05) compared with vaporizers undergoing service and calibration only annually. Using a questionnaire, we found that fewer than 30% of the anaesthetists using the vaporizers would accept aberrance beyond +/- 10% relative of the dial setting.     

Cause of the continuous rise in plasma renin concentration after removal of manipulated submaxillary glands in nephrectomized mice

After gentle manipulation with subsequent removal of the submaxillary glands in nephrectomized mice there is a vast increase in the concentrations of high molecular weight renin ("prorenin"?) as well active renin in plasma. The increase in active renin is continuous even after removal of glands as well as kidneys. Using in vitro incubation and replacement transfusion experiments, the continuous rise was found not to be due to activation of the high molecular weight renin. The continous increase could instead be shown to be due to a rapid transfer of submaxillary lymph and (or) interstitial fluid to the surrounding tissues, with a subsequent slower release from these tissues to the blood. Continued release of renin from extra-submaxillary tissue-depots is probably also the cause of the continuance of the high plasma renin concentrations for several hours after the removal of the manipulated glands, which contrast with the much more rapid decline in the concentration after injection of extracts of submaxillary glands as well as after injection of pure submaxillary renin.     

D-penicillamine-induced myasthenia gravis in a case of eosinophilic fasciitis

During the period 1983-1995, 200 chronic renal failure patients (115 males and 85 females) were parathyroidectomized for hyperparathyroidism in our Department. In all of them, the presenting clinical symptoms, physical signs, biochemical and radiological tests were typically those of hyperparathyroidism. One hundred ninety patients were operated for the first time whereas 10 were re-operated due to relapse of the disease; 3 of these cases were primary hyperparathyroidism, 182 secondary and 5 tertiary. All three primary hyperparathyroidism cases underwent removal of the adenoma; in the group of secondary hyperparathyroidism, 50 underwent removal of all the parathyroid glands found, 25 underwent total parathyroidectomy with forearm or deltoid autograft and 60 subtotal parathyroidectomy whereas in 39 and 8 patients only 3 and 2 parathyroid glands were found respectively. In the group of tertiary hyperparathyroidism, we removed only the hyperplastic gland detected as the operative detection of the rest was not possible. Ten cases were re-operated for removal of the remaining glands. No complications were noted postoperatively, apart from severe hypocalcemia in 20 cases, treated successfully by Calcium and Vitamin D administration. The highest relapse rate was noted among the 8 patients with only the 2 parathyroid glands removed. It seems that total or subtotal parathyroidectomy represents the most successful methods for surgical treatment of hyperparathyroidism complicating chronic renal failure.     

Sensitivity of the MTI photoscreener for amblyogenic factors in infancy and early childhood

BACKGROUND: Screening for amblyogenic factors in infancy by pediatricians is unsatisfactory, as they hardly ever detect ametropia or microstrabismus. As photoscreening seems to be a helpful method to detect even small squint angles and refractive errors, we tested the MTI photoscreener for its sensitivity with respect to amblyogenic factors. PATIENTS AND METHODS: One hundred and twelve children aged 6-48 months were first examined with the MTI photoscreener. Then each child underwent complete medical examination by an ophthalmologist and an orthoptist. The examination included the Hirschberg test (corneal reflex evaluation), the Brückner test (fundus red reflex), and, where possible, the Lang stereotest, the cover test and visual acuity assessment, as well as a motility test, biomicroscopy, ophthalmoscopy in mydriasis and refractometry in cycloplegia. Exclusion criteria were any organic pathological results, manifest strabismus, ametropia > or = 2 D and astigmatism > or = 1 D. An orthoptist, a pediatrician and two ophthalmologists independently evaluated the Polaroid pictures according to the criteria given in the handbook of the MTI photoscreener. RESULTS: For 10 children the evaluation with the MTI photoscreener was not possible despite the fact that photographs were retaken several times. Thirteen photographs showing obvious pathologic findings despite their poor quality were included. Eighty-three of the remaining 102 children failed the eye examination according to the above-mentioned criteria. The mean sensitivity of the MTI photoscreener was determined to be 82.8%. The ability to correctly identify the absence of any amblyogenic factors (specificity) was 61.8%. CONCLUSIONS: Sensitivity was high when compared to the usually low detection rate during pediatric examinations. Due to the low specificity, effectiveness was poor. Therefore an ophthalmological examination should be included in the preventive screening during infancy and early childhood.     

Analysis of proliferative activity of the parathyroid glands using proliferating cell nuclear antigen in patients with hyperparathyroidism

To elucidate the cellular proliferative kinetics of the parathyroidal gland in patients with hyperparathyroidism, we investigated the expression of proliferating cell nuclear antigen (PCNA) in parathyroidal tissues using an immunohistochemical procedure. The PCNA labeling index (LI; maximum LI, maximal stained area; average LI, evenly distributed stained area) indicating cellular proliferative activity was defined as the number of PCNA-positive cells per 1000 parathyroid cells in the region of interest. We used these indexes to compare and investigate the proliferative activity of parathyroid cells under various conditions. The specimens used for the study were 42 parathyroid glands from 21 patients with primary hyperparathyroidism (19 cases of adenoma and 2 cases of primary hyperplasia due to multiple endocrine neoplasia type 1) and 129 parathyroid glands from 32 patients with secondary hyperparathyroidism. An additional 40 parathyroid glands resected during thyroid surgery of 30 normocalcemic patients were used as normal controls. In normally functioning parathyroids, a small number of cells in the growth phase were found. In primary hyperparathyroidism, proliferative activity was highest in the adenoma followed by primary hyperplasia. In contrast, the PCNA LIs showed a low value in the normal rim of the adenoma and normal glands resected as biopsy specimens from adenoma patients. We, therefore, assumed that proliferative activity was suppressed in these cells compared with that in normally functioning glands. In secondary hyperparathyroidism, when the cell component of the parathyroid tissues was divided into five types, PCNA immunoreactivity was lowest in the dark chief cells. Proliferative activity in cells of the oxyphil series was the same or higher than that in the clear chief cells or vacuolated chief cells. When classified according to the structure of the parathyroid glands, cell proliferation was significantly higher in the nodular type than in the diffuse type (maximum LI, 176 +/- 231 vs. 38.3 +/- 55.7; average LI, 120 +/- 188 vs. 24.8 +/- 43.5; mean +/- SD; P < 0.001). More PCNA-immunoreactive cells were found in autotransplanted glands with recurrence than in glands resected during the initial surgery. To summarize the PCNA expression classified according to the pathological types of hyperparathyroidism, the PCNA LIs were highest in secondary hyperplasia (maximum LI, 144 +/- 212; average LI, 96.0 +/- 169) and adenoma (maximum LI, 102 +/- 81.7; average LI, 67.5 +/- 67.7), followed by primary hyperplasia (maximum LI, 25.0 +/- 25.4; average LI, 19.2 +/- 22.2) and normal glands (maximum LI, 13.6 +/- 23.9; average LI, 4.40 +/- 8.90). These findings suggest that the cellular proliferative kinetics of the parathyroid gland differ depending on the type of hyperparathyroidism, glandular structure, and cell components. As the detection method of intranuclear expression of PCNA in cells is too sensitive, we should be careful not to overestimate the number of cells in the proliferative cycle. However, these results could not have been obtained using a conventional method such as DNA analysis by flow cytometry.