The synthesis of mono- and bifunctional nitriles and imidoesters carrying a fluorescent group.

The synthesis of nitriles and dinitriles carrying fluorescent dansyl groups is described. From these compounds the corresponding mono- and bifunctional imidoesters were prepared. They are suitable for labelling or crosslinking, respectively, of proteins under mild conditions.     

The Morse taper junction in modular revision hip replacement--a biomechanical and retrieval analysis.

All biomaterials used for total joint surgery are subjected to wear mechanisms. Morse taper junctions of modular hip revision implants are predilection sites for both fretting and crevice corrosion, dissociation and breakage of the components. The aim of this study is to quantify wear and study metallurgical changes of Morse taper junctions of in-vitro and in-vivo loaded modular revision stems. Three modular revision stems (MRP-Titan, Peter Brehm GmbH, Germany) were loaded by a servohydraulic testing machine. The loads and conditions used exceeded by far the values required by ISO-standard 7206. The tests were performed with maximum axial loads of 3,500 N to 4,000 N over 10-12 x 10(6) cycles at 2 Hz. Additionally, the female part of the taper junctions were coated with blood and bone debris. The free length of the implant was set to 200 mm. One other MRP stem was investigated after retrieval following 5.5 years of in-vivo use. All contact surfaces of the modular elements were assessed by visual inspection, optical microscopy and scanning electron microscopy (SEM). The degree of plastic deformation of the male part of the morse taper junction was determined by contouroscopy. None of the morse taper junctions broke or failed mechanically. Corrosion and wear affected all tapers, especially at the medial side. The retrieved implant showed no cracks and the amount of debris measured only one third of that for the stems tested in-vitro. The present retrieval and laboratory investigations have proven, that the morse taper junctions of the MRP-titanium stem are stable and resistant to relevant wear mechanisms. The longevity of the junctions for clinical use is given. If an optimal taper design is selected, the advantages of modular femoral components in total hip revision arthroplasty will outweigh the possible risks.     

Studies on the ultrastructure of the rotifer Habrotrocha rosa Donner (Aschelminthes)

The alimentary system of Habrotrocha rosa is composed of the alimentary channel, five digestive glands and another gland which is in close relation to the intestinal syncytium. After the present investigation, the alimentary channel can be divided into sections which clearly differ from each other, these are: oral cavity, pharynx, oesophagus, mastax, stomach-hose, syncytium of intestine, and terminal intestine.     

Phyllobacterium calauticae sp. nov. isolated from a microaerophilic veil transversed by cable bacteria in freshwater sediment

Antonie van Leeuwenhoek - Microaerophilic veils of swimming microorganisms form at oxic-anoxic interfaces, mostly described in sediments where sulfide from below meets oxygen diffusing in from the...     

Effect of treatment with methylprednisolone on duration of pseudopregnancy and on macrophages and T lymphocytes in rabbit corpora lutea.

The potential role of macrophages and T lymphocytes in the destruction of the corpus luteum at the end of the luteal phase was investigated by treating pseudopregnant rabbits with the immunosuppressant glucocorticoid methylprednisolone. Eleven specific pathogen-free New Zealand White rabbits were injected with pregnant mares' serum gonadotrophin (40 iu, i.m.), followed 2 days later by human chorionic gonadotrophin (40 iu, i.v.) to stimulate ovulation. The following day (day 1 of pseudo-pregnancy) all animals had an oestradiol-filled Silastic capsule implanted s.c., to ensure that oestradiol, the luteotrophic hormone in this species, would not be limiting. From day 10 of pseudopregnancy, three animals were injected with a low dose of methylprednisolone (2 mg kg-1 per day) until day 20. Three other animals were injected with a higher dose of methylprednisolone (20 mg kg-1 per day) from day 13 of pseudopregnancy until day 19. Five animals served as control, vehicle-injected animals. Blood samples were taken at intervals and assayed for progesterone. Immunofluorescence was used to stain luteal tissue for macrophages, T lymphocytes and class II antigens, and positive cells were counted under high-power magnification. Methylprednisolone treatment reduced (by about 70%), but did not eliminate, the macrophages in the regressing corpora lutea. In contrast, the high dose of methylprednisolone essentially eliminated T lymphocytes, and reduced (by about 90%) the number of cells expressing class II antigen in the luteal tissue. Despite the effects of methylprednisolone on these cells, serum progesterone profiles were not altered by treatment with methylprednisolone, and pseudopregnancy was of normal duration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Spontaneous and induced ovulation in the lion (Panthera leo)

The objective of this study was to clarify if ovulation occurs spontaneously, if it is copulation-induced, or if a combination of both mechanisms controls ovulation in African lions. Five female lions were either permitted unrestricted copulatory activity with vasectomized males throughout estrus or were physically isolated from conspecifies for the duration of estrus. Each female was randomly exposed to each treatment in a switchback design during consecutive estrous cycles. Serum concentrations of progesterone were determined in blood samples collected on days 2, 8, 12, and 16 following the onset of estrus (day 0). Ovulation was indirectly confirmed by elevated serum concentrations of progesterone on days 8, 12, and 16. While ovulation occurred spontaneously in one of five isolated lions, five of five of the same lions ovulated following copulation (P ≤ 0.05). Following mating, concentrations of progesterone increased six- to twelve fold (up to > 109 ng/ml) between days 2 and 12, while in the same lions failing to ovulate following isolation, progesterone concentrations did not exceed 11 ng/ml by day 16. Inter-estrous intervals following mating (67 ± 4.4 days) were longer (P ± 0.05) than those following isolation (19 ± 1.0 day). Thus, ovulation in African lions appears to be induced by copulatory stimuli or some other form of physical or social interaction with conspecifies during estrus but can occasionally occur spontaneously. The lion, therefore, does not appear to be a classic spontaneous ovulator but rather a reflex ovulator like the domestic cat. © 1994 Wiley-Liss, Inc.     

Brown trout Salmo trutta f. Fario liver ultrastructure as a biomarker for assessment of small stream pollution

T he effects of environmental pollutants from two small streams in south-west Germany on the liver of brown trout (S almo trutta f. Fario ) were studied as biomarkers by means of quantitative and semi-quantitative electron microscopy, and quantitatively by morphometrical measurements. Cellular damage was assessed semi-quantitatively based on a classification of ultrastructural responses. Both methods revealed more severe cellular effects in the liver of trout which had been exposed to the highly polluted stream than in those exposed to the lightly polluted river. Morphometrical studies showed a significant reduction of glycogen storage and a significant increase in number of mitochondria, peroxisomes and cisternae of the endoplasmic reticulum. The biomarker responses of this study were correlated with the results obtained by limnological and analytical investigations, and reflect the levels of pollution in each stream.