In vivo MRI of cancer cell fate at the single-cell level in a mouse model of breast cancer metastasis to the brain.

Metastasis (the spread of cancer from a primary tumor to secondary organs) is responsible for most cancer deaths. The ability to follow the fate of a population of tumor cells over time in an experimental animal would provide a powerful new way to monitor the metastatic process. Here we describe a magnetic resonance imaging (MRI) technique that permits the tracking of breast cancer cells in a mouse model of brain metastasis at the single-cell level. Cancer cells that were injected into the left ventricle of the mouse heart and then delivered to the brain were detectable on MR images. This allowed the visualization of the initial delivery and distribution of cells, as well as the growth of tumors from a subset of these cells within the whole intact brain volume. The ability to follow the metastatic process from the single-cell stage through metastatic growth, and to quantify and monitor the presence of solitary undivided cells will facilitate progress in understanding the mechanisms of brain metastasis and tumor dormancy, and the development of therapeutics to treat this disease.     

Effect of Rb+ on cromakalim-induced relaxation and ion fluxes in guinea pig trachea.

The effects of cromakalim, verapamil and salbutamol have been examined in guinea pig trachealis smooth muscle in both Krebs physiological salt solution and Krebs solution where K+ has been replaced by Rb+. Cromakalim-induced relaxation in the presence of Rb+ was reduced in extent and became transient, whilst the relaxation response to verapamil was enhanced and that to salbutamol unaffected. The transient relaxation occurring in Rb+ was blocked by quinidine and glibenclamide. The presence of extracellular Rb+ also prevented cromakalim-stimulated efflux of both 86Rb+ and 42/43K+. There was, however, no effect on cromakalim-stimulated 86Rb+ uptake. It is proposed that cromakalim is opening two populations of potassium channel in guinea pig tracheal smooth muscle, one of which is susceptible to blockade by Rb+ and one of which is not. The latter channel appears to play the dominant role in cromakalim-stimulated uptake, and is responsible for the transient relaxation response in the presence of rubidium, whilst the former is responsible for the maintained relaxation.     

Fleroxacin pharmacokinetics in patients with liver cirrhosis.

In this open-label study, the disposition of fleroxacin in liver disease in 12 healthy male volunteers, 6 male cirrhotics without ascites (group A), and 6 male cirrhotics with ascites (group B) was evaluated. Fleroxacin (400 mg) was administered orally and intravenously to each subject in a random crossover fashion. Fleroxacin was completely absorbed and achieved similar peak concentrations in plasma in all three study groups (P greater than 0.05). The volume of distribution exceeded 1 liter/kg in healthy controls and was not affected by liver impairment (P greater than 0.05). Only group B demonstrated differences in the pharmacokinetic parameters evaluated: the systemic and renal clearances of fleroxacin and the renal clearances and clearances of the two major metabolites of fleroxacin formed, N-demethyl fleroxacin and fleroxacin N-oxide, were significantly lower and the half-lives of the parent drug and its metabolites were significantly longer in group B than in healthy controls and group A (P less than 0.05). The elimination of the two metabolites appeared to be formation rate limited in all three study groups. It was concluded from this study that a 50% reduction in the fleroxacin maintenance dose in patients with liver disease appears justified only in patients with ascites. However, no change in the fleroxacin loading dose is needed in patients with compromised liver function.     

Vitamin A2-based visual pigments in fully terrestrial vertebrates.

As part of a broad study of the ocular and extraocular photoreceptors of reptiles, we have used high performance liquid chromatography (HPLC) to identify the retinoids present in whole eye extracts of the arboreal lizard Anolis carolinensis and the non-arboreal ruin lizard Podarcis sicula. Unexpectedly, only vitamin A2-derived chromophore was detected in Anolis, while a mixture of vitamin A1- and vitamin A2-derived chromophores was detected in Podarcis. These are the first examples of fully terrestrial vertebrates using vitamin A2-derived chromophore for visual pigment generation. Furthermore, microspectrophotometric (MSP) data for Anolis show a class of photoreceptor having a visual pigment with maximum absorbance at about 625 nm, some 40 nm further into the red than has been found in any terrestrial vertebrate examined to date.     

Use of a Strecker oesophageal stent in the treatment of benign oesophageal stricture

The use of self-expanding prostheses in the management of malignant oesophageal strictures has become well established. The majority of benign peptic oesophageal strictures can be successfully managed using endoscopic or fluoroscopically guided balloon oesophageal dilatation combined with long-term drug therapy, particularly using proton pumper inhibitors. Although endoscopic oesophageal dilatation can be performed on an outpatient basis, it requires repeated hospital visits. There is a small risk of oesophageal perforation whilst cardio-respiratory complications may be encountered during the use of intravenous sedation in an elderly population. The use of a self-expanding Strecker stent in a 98 year old woman with a benign oesophageal stricture is described.     

Secretion of human hepatitis B virus is inhibited by the imino sugar N-butyldeoxynojirimycin.

The imino sugar N-butyldeoxynojirimycin (NBDNJ) is a potent inhibitor of the oligosaccharide-trimming enzyme alpha-glucosidase I. Hepatitis B virus (HBV) contains three surface proteins (HBs proteins) of different sizes that are singly or doubly N-glycosylated and are essential for the formation of infectious virus. Therefore, the replication and secretion of HBV in the human hepatoma cell line HepG2 were studied in the presence of NBDNJ. In the stably HBV-transfected HepG 2.2.15 cells and in HBV-infected HepG2 cells, NBDNJ suppressed secretion of HBV particles and caused intracellular retention of HBV DNA. The secretion of subviral particles was less affected. These data suggest that inhibitors of oligosaccharide trimming may be useful for antiviral therapy of hepatitis B and for the study of the intracellular transport of the viral glycoproteins.