Efficiency of initiating cell adhesion in hydrodynamic flow

We theoretically investigate the efficiency of initial binding between a receptor-coated sphere and a ligand-coated wall in linear shear flow. The mean first passage time for binding decreases monotonically with increasing shear rate. Above a saturation threshold of the order of a few 100 receptor patches, the binding efficiency is enhanced only weakly by increasing their number and size, but strongly by increasing their height. This explains why white blood cells in the blood flow adhere through receptor patches localized to the tips of microvilli, and why malaria-infected red blood cells form elevated receptor patches (knobs).

Identification of functionally relevant histidine residues in the apoptotic nuclease CAD

The caspase-activated DNase CAD (DFF40/CPAN) degrades chromosomal DNA during apoptosis. Chemical modification with DEPC inactivates the enzyme, suggesting that histidine residues play a decisive role in the catalytic mechanism of this nuclease. Sequence alignment of murine CAD with four homologous apoptotic nucleases reveals four completely (His242, His263, His304 and His308) and two partially (His127 and His313) conserved histidine residues in the catalytic domain of the enzyme. We have changed these residues to asparagine and characterised the variant enzymes with respect to their DNA cleavage activity, structural integrity and oligomeric state. All variants show a decrease in activity compared to the wild-type nuclease as measured by a plasmid DNA cleavage assay. H242N, H263N and H313N exhibit DNA cleavage activities below 5% and H308N displays a drastically altered DNA cleavage pattern compared to wild-type CAD. Whereas all variants but one have the same secondary structure composition and oligomeric state, H242N does not, suggesting that His242 has an important structural role. On the basis of these results, possible roles for His127, His263, His304, His308 and His313 in DNA binding and cleavage are discussed for murine CAD.

IDEA: a large-scale project on electronic identification of livestock

The aim of the IDEA (Identification électronique des animaux) project is to collect information on the feasibility of the introduction into the European Union (EU) of an animal electronic identification system, as referred to in Directive 92/102 and Regulation 1760/2000. The project will run for a period of four years (1998-2001) and will include one million animals in six countries (France, Germany, Italy, The Netherlands, Portugal and Spain). The Joint Research Centre, as technical co-ordinator of the project, provides technical support in terms of testing and certification of electronic identification devices, establishment of the central database, transmission and recording of data and evaluation of results. Identification has been undertaken in cattle, sheep, goats and buffalo using three types of electronic tags (ruminal bolus, ear tag and injectable transponder). The performance of these tags is checked at defined intervals until recovery in the slaughterhouse. The evaluation of the results in terms of the performance of the device and the necessary organisational support structures will lead to recommendations for a system to trace animals from birth to slaughterhouse, including the appropriate technology to be applied in any generalised system for the livestock sector in the EU.

Genetic engineering of Escherichia coli to produce a 1:1 complex of the anabaena sp. PCC 7120 nuclease NucA and its inhibitor NuiA

A series of T7-promoter based bicistronic expression vectors was constructed in order to produce the complex of the Anabaena sp. PCC 7120 DNA/RNA non-specific nuclease NucA and its inhibitor NuiA. With all constructs, tandem expression of nucA and nuiA results in aggregation and inclusion body formation of NucA, independent of the order of the genes, the relative expression of the two proteins and the temperature applied during expression. Two constructs in which nuiA is the first and nucA the second cistron lead to an approximately one order of magnitude higher expression of nuiA compared with nucA. In these cells inclusion bodies are formed which contain NucA and NuiA in a 1:1 molar ratio. The complex can be solubilized with 6M urea after disruption of the cells by sonication, renatured by dialysis and purified to homogeneity. 2mg of the complex are obtained from 1l Escherichia coli culture. As shown by gel filtration and analytical ultracentrifugation, our system leads to a highly pure and homogeneous complex preparation, as required for biophysical and structural studies. Thus, our new method is a superior alternative for the production of the NucA/NuiA complex in which separately produced nuclease and inhibitor are mixed, and an excess of one or the other component, as well as aggregates of NucA, have to be removed from the preparation.

Synergistic effects of ularitide acetate with classical bronchorelaxants on guinea-pig tracheal smooth muscle

Ularitide (CAS 118812-69-4, urodilatin) is a member of the family of the atrial natriuretic peptides. In the present study, the relaxant effects of ularitide acetate, isoproterenol (isoprenaline) hemisulfate, aminophylline, zaprinast, and different combinations between these drugs were investigated on methacholine chloride-precontracted guinea-pig tracheal smooth muscle. Ularitide acetate was a weaker bronchorelaxant than isoproterenol hemisulfate and aminophylline. Moreover the relaxation induced by ularitide acetate was reversible, while the relaxation induced by isoproterenol hemisulfate, aminophylline, and zaprinast was irreversible. Combinations between in each case two of these substances were overadditive, if the phosphodiesterase-inhibiting component was applicated before the combination partner. Their effects were only additive, if the combination partners were applicated simultaneously. All combinations between ularitide acetate and isoproterenol hemisulfate, aminophylline, or zaprinast respectively relaxed the tracheas irreversibly. These results suggest that ularitide acetate might be a novel partner for classical bronchorelaxants in potent bronchorelaxing combinations in the therapy of asthma bronchiale.

Comparison of the effects of ularitide acetate and other bronchorelaxing substances on the thrombin-induced permeability raise of human endothelial cell monolayers

Endothelial cell contraction plays a pivotal role in vascular leakage. It increases the extravasation of fluid and macromolecules from the lumen into the interstitium. This is also true for bronchial edema. Previous studies have indicated that an elevation of intracellular adenosine-3',5'-cyclic monophosphate (cAMP) or guanosine-3',5'-cyclic monophosphate (cGMP), respectively, can counteract this vascular leakage by improving the endothelial barrier function in analogy to the relaxation of smooth muscle cells. To investigate the potential antiedemateous effects of ularitide acetate (CAS 115966-23-9), isoproterenol hemisulfate (CAS 6078-56-4), sodium nitroprusside (CAS 13755-38-9, SNP), aminophylline (CAS 317-34-0), and combinations of these compounds, their effects on thrombin-induced macromolecular permeability raise in relation to cGMP- or cAMP-levels, respectively, in a model of human umbilical vein endothelial cells (HUVECs) were examined. Ularitide acetate, isoproterenol hemisulfate, and SNP all increased the amount of cyclic nucleotides and decreased the raise in permeability in the following order of potency: isoproterenol hemisulfate > ularitide acetate > SNP. Aminophylline raised both cGMP- and cAMP-levels in a weaker amount and was not able to decrease the thrombin-induced permeability raise on its own. By way of contrast, preincubation of HUVECs with aminophylline resulted in a more than additive potentiation of the cGMP-levels and the permeability lowering induced by ularitide-acetate. These in vitro-data indicate that ularitide-acetate, especially in combination with phosphodiesterase (PDE) inhibitors, could probably have beneficial effects in bronchial permeability edema.

Vocational outcome of aphasic patients following severe traumatic brain injury

The incidence and course of aphasia, and its impact on vocational outcome, were determined in a group of 351 patients with severe traumatic brain injury (TBI). Aphasia was found in 11.1%, the common forms being amnestic (56%, 22/39), expressive (10.3%, 4/39) and receptive (10.5%, 8/39), as found on the first language assessment. No age difference was found between the aphasic and non-aphasic patients. Coma was more common in the aphasics than the non-aphasics (95% and 82%, respectively), although its mean duration was shorter. Aphasics had more severe locomotor deficits (p < 0.01, Fisher test) and tended towards more severe cognitive disorders (p = 0.07, Fisher test). There was no difference between the groups in incidence of behavioural disturbances or occupational outcome. Most of the aphasic patients improved after therapy, and two recovered completely. The presence of aphasia did not have negative prognostic implications for occupational outcome.

Recall of informed consent after endoscopic procedures

PURPOSE

The aim of this study was to determine if recall of informed consent is affected by the timing of obtaining informed consent before endoscopic procedures.

METHODS

Sixty patients scheduled for colonoscopy or esophagogastroduodenoscopy were enrolled in this prospective, randomized study. Each patient received informed consent 24 to 72 hours or immediately before the procedure, and follow-up occurred one to three days postprocedure.

RESULTS

There was no statistically significant difference in recall of informed consent or the individual elements of informed consent (indication, risks, benefits, alternatives) between the two groups.

CONCLUSION

Recall of informed consent is similar whether consent is obtained immediately or several days before endoscopic procedures.

Non-exponential behavior of the nuclear magnetization in H-doped copper oxides

Measurement of the spin lattice relaxation time in H-doped Y2BaCuO5 and YBa2Cu3O6 has revealed a power law growth of the nuclear magnetization M for short times following a saturation pulse sequence. Preliminary experimental results yield exponents of 1/2 and 1/3, depending on the amount of hydrogen present in the sample. We extend Blumberg's theory for relaxation due to paramagnetic centers via dipole-dipole interaction in the absence of spin diffusion to obtain M approximately tD/6 where D is the dimensionality of the system. This yields exponents of 1/2 and 1/3 for three- and two-dimensional systems, respectively. At long times the magnetization growth becomes exponential.

Frequency selectivity as a potential measure of noise damage susceptibility

The notched-noise procedure of Patterson (1974, Journal of the Accoustical Society of America, 55, 802-809; 1976, Journal of the Acoustical Society of America, 59, 640-654) was employed in revealing changes in auditory frequency selectivity (FS) in noise-exposed industrial workers in manufacturing plants in which noise levels in the working environment exceeded 90 dB(A). With 4 kHz as the test frequency, both threshold and FS measures were applied to three groups of non-exposed young adults (total N = 61) for reference values and to workers in three different factories, some ('noise-exposed') working in noise levels over 90 dB(A) (total N = 222). In another study involving 185 workers only the FS test was repeated after a work session, and the results are reported on 31 who worked in high noise levels. Pre-work-shift data showed that when thresholds were better than 30-dB HL most FS values were 10 dB or more, while subjects with hearing threshold levels beyond that showed reduced FS. Two post-work-shift studies of 144 ears of the noise-exposed workers showed significant deleterious changes in both thresholds and FS but the relationships were different in the two studies. The findings indicate that the notched-noise test is sensitive to noise-induced auditory damage, even after a single work-shift. Attractive features of the procedure are that it reduces the need for a quiet test environment and that it can be more resistant to testee manipulation or threshold 'learning' effects, often seen in industrial audiometric testing.

Biopercular lesions and acquired mutism in a young patient

A 13-year-old patient developed complete mutism and buccofacial apraxia following toxic vasculitis due to a yellow scorpion sting. Language functions were preserved. A CT scan disclosed mainly biopercular infarcts. It is suggested that the lost control of vocalization and speech is associated with biopercular lesions and that a preserved right opercular region can take over this function in the presence of damage to homologous left opercular region.

Interferon-gamma-increased adherence of lymphocytes to high endothelial venules

Recirculating lymphocytes specifically adhere to and migrate through endothelium lining high endothelial venules (HEV), using specific and non-specific receptor-ligand systems. Interferons (IFN) profoundly affect the traffic of lymphocytes. Therefore the effects of interferon-gamma (IFN-gamma) on lymphocytes with respect to their interaction with HEV endothelium in lymph nodes were studied using the frozen section assay. In addition the organ-specificity of T- and B-lymphocyte adherence to HEV was investigated. Lymphocytes from spleen and peripheral lymph nodes showed increased binding to HEV of up to 35% compared to control lymphocytes after in vivo administration of IFN-gamma. The specificity of their binding did not change in terms of T:B-cell ratios. Increased adherence was also found by preincubation of lymphocytes with IFN-gamma in The enhanced binding was not due to increased expression of Mel-14 homing receptors and LFA-1 molecules on T and B lymphocytes, as shown by fluorescence-activated cell sorter analysis and antibody-blocking studies in the frozen section assay. Apparently IFN-gamma induces an additional Mel-14-independent and LFA-1-independent adhesion mechanism on lymphocytes.

Improved phonation during fever in brainstem dysarthrophonia

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Light microscopical detection of single 5 and 20 nm gold particles used for immunolabelling of plasma membrane antigens with silver enhancement and reflection contrast

To detect plasma membrane antigens, cytocentrifuge preparations of the macrophage-like cell line P388D1 were incubated with monoclonal antibodies and labelled with 5 and 20 nm gold particles conjugated to immunoglobulins or protein A. The 20 nm, but not the 5 nm, particles could be observed by reflection-contrast light microscopy. Single 5 nm particles, however, were clearly demonstrable with silver contrast enhancement, both in absorption contrast and in reflection contrast. The method proved to be compatible with cytochemical methods such as acid phosphatase.

False localization of acid phosphatase activity in the nuclear envelope and endoplasmic reticulum of peritoneal macrophages

Acid phosphatase cytochemistry using lead salt methods was performed on rat peritoneal macrophages obtained by the intraperitoneal injection of dextran five days previously. Lead precipitate was present in the nuclear envelope, the rough endoplasmic reticulum, Golgi apparatus and lysosomes in about 50% of these cells. The formation of reaction product appeared to be substrate-specific and was sensitive to sodium fluoride in all these sites. However, only in the nuclear envelope, the rough endoplasmic reticulum and Golgi apparatus could lead salt precipitation be prevented by (a) omission of the washing procedure following the incubation step, (b) postincubation in a medium containing sodium fluoride, or (c) washing in buffer containing lead salt. It is concluded that precipitation of lead salt does not prove the presence of acid phosphatase activity in these organelles. The formation of precipitate in these sites is probably due to a local matrix effect, facilitated by the persistence of acid phosphatase activity in the lysosomes and a suboptimal trapping efficiency of phosphate ions during the washing procedure which follows in the incubation step.

Characterization of the population of phagocytic cells in thymic cell suspensions. A morphological and cytochemical study

Rat thymic phagocytic cells were characterized in vitro using various light- and electron-microscopical techniques. Thymic cell suspensions were mechanically prepared and enriched for non-lymphoid cells, which were predominantly phagocytic and of three types. Type I showed acid phosphatase (APh) activity in small granules dispersed throughout the cytoplasm and were mostly Ia antigen-positive, although the Ia membrane label varied in intensity and distribution among individual cells. Only a few cells had endogenous peroxidase activity. The type-I cells could not be clearly distinguished morphologically from type-II or -III cells, and most likely comprise precursors of both these cell types. Type-II were large pale cells with many slender cell processes. These cells had APh activity centrally positioned, were strongly positive for Ia on the cell membrane and were negative for endogenous peroxidase. The cytoplasm frequently contained Birbeck granules, which unequivocally classifies these cells as the in vitro equivalent of the interdigitating cells present in the medullary area of the thymus in situ. Type-III cells were rounded with a smooth or ruffled cell membrane and contained vacuoles and many phagolysosomes. They were strongly positive for APh which was present throughout the cytoplasm. About 50% of these cells were positive for endogenous peroxidase in a pattern resembling resident macrophages. The cells were negative for Ia antigens. Type-III cells mostly likely represent the macrophages found in the cortical area of the thymus.

Trypanosoma cruzi: comparative studies of infectivity of parasites ingested by Triatoma infestans and those present in their feces

Artificial feeding of the insects with whole blood containing trypomastigotes resulted in triatome infection; the parasites were present in the host feces after 15--30 days and, when inoculated into mice, elicited parasitemia in 100% of the cases and deaths in 20--70%. This mortality indicates a reduction of the original infective capacity of the bloodstream form, which kills 100% of the mice even when inoculated with a single trypomastigote. When triatomes were fed whole normal mouse blood containing culture forms of low infective capacity (TulL), mice inoculated with feces containing the progeny of the culture forms failed to develop a parasitemia. The absence of any infective capacity of these parasites was proven when the mice challenged with lethal doses of trypomastigotes 30 days after the fecal inoculations died at the same time as the controls. Mice injected with feces from triatomes fed culture forms with high infectivity for mice (TulB) developed patent parasitemia, indicating that triatomes may be infected by parasite forms other than bloodstream trypomastigotes. Experiments on infectivity of parasites present in the feces of triatomes fed TulL and TulB culture forms, also showed a single passage through the digestive tract of the insects did not significantly modify the infective capacity of the parasite population. When stomachs and intestines from insects fed TulB were processed separately, parasites obtained from the latter showed higher infectivity for mice than those obtained from the former.