2-Methyl-3-oxo-4-phenyl-2,3-dihydrofuran-2-yl acetate: a fluorogenic reagent for detection and analysis of primary amines

A new fluorogenic reagent, 2-methyl-3-oxo-4-phenyl-2,3-dihydrofuran-2-yl acetate, has been developed for the analysis of primary amines and aminated carbohydrates by means of HPLC, CE, and MALDI/MS. Peptides at 1 pmol (2 x 10(-7) M) levels were successfully labeled and analyzed through CE. The fluorescent derivatives have good stability in both acidic and basic solutions, making their further manipulation and structural analysis possible. The derivatives can be analyzed in reversed-phase HPLC due to the hydrophobic nature of this fluorescent tag. Characteristic elution intervals between the diastereomeric peaks of the chiral peptide derivatives may be used in structural verification. The labeled peptides and neutral oligosaccharides are also readily detectable through MALDI/MS in its positive mode.     

Continued development of the Nimbus/University of Pittsburgh (UOP) axial flow left ventricular assist system

Nimbus and the University of Pittsburgh (UOP) have continued the development of a totally implanted axial flow blood pump under the National Institutes of Health (NIH) Innovative Ventricular Assist System (IVAS) program. This 62 cc device has an overall length of 84 mm and an outer diameter of 34.5 mm. The inner diameter of the blood pump is 12 mm. It is being designed to be a totally implanted permanent device. A key achievement during the past year was the completion of the Model 2 pump design. Ten of these pumps have been fabricated and are being used to conduct in vitro and in vivo experiments to evaluate the performance of different materials and hydraulic components. Efforts for optimizing the closed loop speed control have continued using mathematical modeling, computer simulations, and in vitro and in vivo testing. New hydraulic blade designs have been tested using computational fluid dynamics (CFD) and flow visualization. A second generation motor was designed with improved efficiency. To support the new motor, a new motor controller fabricated as a surface mount PC board has been completed. The program is now operating under a formal QA system.     

Experimental toxoplasmosis in broiler chicks

To evaluate chicken toxoplasmosis both as an economic and a public health subject, 84 broiler chicks of a commercial strain, 30 days old, were distributed into seven groups of 12 birds (three replications of four chicks) experimentally infected with three developing T. gondii stages of the P strain as follows: tachyzoites, intravenous (two groups: 5.0 x 10(5) and 5.0 x 10(6)), cysts, per os (two groups: 1.0 x 10(2) and 1.0 x 10(3)) and oocysts, per os (three groups: 5.0 x 10(2), 5.0 x 10(3) and 5.0 x 10(4)). Twelve chicks received only a placebo (control group). During the next 30 days the following parameters were estimated: productivity (weight gain and feed conversion), clinical signs, including rectal temperature and parasitemia (bioassay). No clinical signs suggesting toxoplasmosis were seen and no statistical differences on productivity standards were found in comparison between inoculated and control chicks. However, fowls inoculated with tachyzoites and oocysts occasionally showed hyperthermia. Some haematological changes were detected in fowls inoculated with T. gondii. Anatomo-histopathological changes were not observed. From 14 parasitemias detected, 35.7% appeared on the 5th day after inoculation and 57.1% of them resulted from oocysts inoculation. After 30-35 days all birds were slaughtered: fragments from 12 organs or tissues from each of them were subjected to artificial peptic digestion and after that injected into T. gondii antibody-free mice (IIFR). T. gondii was detected in brain (12), pancreas (five), spleen (five), retina (five), kidney (two), heart (four), proventriculus (three), liver (two), intestine (two), lung (one), and skeletal muscle (one). Similar to observations with parasitemia, from 42 T. gondii isolations, 59.5% came from chicks which had received oocysts. It can thus be inferred that the developing form, expelled by cats, is the most important for T. gondii chicken infection and that brain is the most infected organ in birds. Attention must be paid to the potential importance of chicken meat in public health, since T. gondii was isolated from skeletal and heart muscles.     

Limitations of current diagnostic procedures for the diagnosis of Taenia solium cysticercosis in rural pigs

New evidence has been presented from our laboratory that the gliding bacterium, Myxococcus xanthus, does not home by chemotaxis toward a nutrient source. Our experiments, those of others, and the theory presented here combine to suggest a model, called the 'Pied Piper' model. It hypothesizes a gene that has a high mutation rate forward and back (say something in excess 10(-4) mutations per cell generation) which leads to switching between two motility states. Occasionally rare organisms become genetically, but reversibly, changed so that they move unidirectionally instead of mostly forward and back as do the bulk of the cells. When such a 'leader' cell arises, it continues to move in its original orientation, and causes a cohort of cells to move together away from the bulk of the cells. That is, in the less common mutational state it counteracts the usual tendency to just move forward and backward achieving little net movement. The assumption of a genetic element that mutates in a reversible way is suggested by numerous cases of reversible switches now known in a wide range of bacteria serving a variety of functions. A second aspect of the model is that mechanisms exist that cause cells to move in the same direction as their nearby neighbors. This process results in a regular spacing of bands of cells to form mounds in the absence of a leader. The action of C-factor, a factor-secreted by the cells which has been largely studied in the laboratory of Dale Kaiser, and extracellular fibrils, (rod-shaped protein and carbohydrate bodies) largely studied in the laboratory of Martin Dworkin, may be key elements in coordinating (or linking) the movements of neighboring cells. Based on the assumption of the absence of chemotaxis, computer simulations of pattern formation for gliding bacterial swarms and flares are consistent with observed behaviors and thus are additional evidence that chemotactic motility of the type exhibited by Escherichia coli, is not necessary for the group movements of M. xanthus. Some tests for this model are suggested.     

Mechanism of the radiation-protective effect of indralin

Output from the interpositus nucleus can inhibit the inferior olive, probably via the GABA-ergic nucleo-olivary pathway. It has been suggested that the function of this inhibition might be to regulate synaptic plasticity resulting from parallel fibre/climbing fibre interaction in cerebellar Purkinje cells, by providing negative feedback information to the olive. Thus, when a learned response, generated by the interpositus nucleus, reaches a sufficient amplitude, the olive would be inhibited and further learning blocked. This suggestion was tested in a classical conditioning paradigm. Decerebrate ferrets were trained using electrical skin stimulation of the forelimb as the conditioned stimulus (CS) and periorbital stimulation as the unconditioned stimulus (US). Climbing fibre responses evoked in Purkinje cells by the US were recorded as surface field potentials in the part of the c3 zone controlling eyeblink. It was found that the CS did not inhibit the olive at the beginning of training, but when conditioned responses were large, the olive was inhibited by the CS in some animals. After a number of unpaired CS presentations, which caused extinction of the conditioned response, the inhibition disappeared. The size of individual conditioned responses correlated negatively with the size of the climbing fibre responses evoked by the US. Climbing fibre responses evoked by direct stimulation of the olive were also inhibited. It was concluded that cerebellar output during performance of a conditioned response inhibits the inferior olive. The results thus support the hypothesis of a cerebellar locus of conditioning and are consistent with the proposed role of cerebello-olivary inhibition.     

Arterial-phase three-dimensional gadolinium magnetic resonance angiography of the renal arteries. Strategies for timing and contrast media injection: original investigation

RATIONALE AND OBJECTIVES: The authors review different imaging and contrast-media infusion strategies for arterial-phase three-dimensional (3D) gadolinium-enhanced magnetic resonance angiography (Gd-MRA). METHODS: The influence of physicochemical factors on the infusion of contrast media, including viscosity, flow rate, inline pressure, and cannula size, is assessed. The combination of manual or automated contrast-media administration with timing-dependent or -independent 3D Gd-MRA techniques is reviewed regarding the aspects of effectiveness, robustness, image quality, and costs. RESULTS: For effective bolus delivery with high flow rates, the type and temperature of the contrast media, the size of the cannula, and an immediate saline flush must be considered. Timing-dependent techniques based on a test bolus and using automated contrast-media infusion as well as timing independent techniques such as MR SmartPrep or multiphase 3D Gd-MRA by using a manual injection with a SmartSet tubing set, are all effective procedures for arterial phase 3D Gd-MRA. CONCLUSIONS: Manual contrast-media injection with a tubing set can be used for timing-independent MRA techniques. The multiphase 3D Gd-MRA approach seems to be favorable for different MR systems, robustness, and speed.     

Flat adenoma: are western colonoscopists careful enough?

There has been recent interest in the risk of various cancers in cystic fibrosis (CF) patients and carriers of cystic fibrosis transmembrane conductance regulator (CFTR) mutations. It has been proposed that a CFTR mutation may protect against breast cancer, based on evidence that elevated extracellular adenosine triphosphate (ATP) is known to inhibit breast cancer cell line growth and that CFTR pumps ATP out of epithelial cells. A CFTR mutation would therefore result in higher concentrations of serum ATP. A CFTR knockout mouse model had high serum concentrations of ATP and showed reduced breast tumour implantibility and decreased breast cancer growth rates. We have evaluated the relationship between the deltaF508 CFTR mutation and the risk of breast cancer before the age of 40. The deltaF508 CFTR mutation carrier rate in 272 cases (2.2%) was no different from the carrier rate observed in 171 controls (1.8%). If there was a protective effect resulting from the postulated elevation in serum ATP levels, tumours arising in deltaF508 CFTR carriers would have been expected to be generally less aggressive. When the histological features of the breast cancers with a deltaF508 CFTR mutation were reviewed and graded using a combined architectural and cytological grading system, all were found to be grade III, poorly differentiated tumours, contrary to the predictions. A combination of our data with other large population-based samples of cases and controls is required to resolve this issue.     

Reaction of melanocytes in vertebrate retina to the exposure to constant magnetic field

The influence of a constant magnetic field (strain 40 kA/m) on retina pigmentary cells of grass frog (Rana temporaria) and grey pigeon (Columba livia) eyes was investigated. Changes in the number and length of melanocytes appendixes were noticed accompanied by formation of thickenings in which melanosomes sized from 0.1 to 0.5 micron are moving. It is established that magnetic properties of eye retina pigmentary cells depend on the presence of Fe3+ in melanin. A theoretical model of paramagnetic receptor has been elaborated, according to which the induction of a magnetic field, formed by melanocyte, makes of the order 100 pT1. This value well compares with the size of magnetic field of a nervous impulse (120 pT1), extending throughout a nervous fibre of the frog sciatic nerve (Wikswo et al., 1980). This allows to suggest a possible unsynaptic way of transferring the information about the perceived magnetic field.