Phylogenetic and physiological diversity of sulphate-reducing bacteria isolated from a salt marsh sediment

Xenopus blastula cells activate different mesodermal genes as a concentration-dependent response to activin, which behaves like a morphogen. To understand how cells recognize morphogen concentration, we have bound naturally labeled activin to cells and related this to choice of gene activation. We find that the increasing occupancy of a single receptor type can cause cells to switch gene expression. Cells sense ligand concentration by the absolute number of occupied receptors per cell (100 and 300 molecules of bound activin induce Xbra and Xgsc, respectively, i.e., 2% and 6% of the total receptors) and not by a ratio of occupied to unoccupied receptors. The long duration of occupancy explains a previously described ratchet effect. Our results suggest a new concept of morphogen gradient formation and interpretation that is particularly well suited to the needs of early development.     

Enhancement of 5-aminolaevulinic acid-induced photodynamic therapy in normal rat colon using hydroxypyridinone iron-chelating agents

Currently, the clinical use of 5-aminolaevulinic acid (ALA)-induced protoporphyrin IX (PPIX) for photodynamic therapy (PDT) is limited by the maximum tolerated oral ALA dose (60 mg kg(-1)). This study investigates whether hydroxypyridinone iron-chelating agents can be used to enhance the tissue levels of PPIX, without increasing the administered dose of ALA. Quantitative charge-coupled device (CCD) fluorescence microscopy was employed to study PPIX fluorescence pharmacokinetics in the colon of normal Wistar rats. The iron chelator, CP94, when administered with ALA was found to produce double the PPIX fluorescence in the colonic mucosa, compared with the same dose of ALA given alone and to be more effective than the other iron chelator studied, CP20. Microspectrofluorimetric studies demonstrated that PPIX was the predominant porphyrin species present. PDT studies conducted on the colonic mucosa showed that the simultaneous administration of 100 mg kg(-1) CP94 i.v. and 50 mg kg(-1) ALA i.v. produced an area of necrosis three times larger than similar parameters without the iron-chelating agent with the same light dose. It is possible, therefore, to increase the amount of necrosis produced by ALA-induced PDT substantially, without increasing the administered dose of ALA, through the simultaneous administration of the iron-chelating agent, CP94.     

Oleate stimulation of incorporation of exogenous glycerol into cardiolipin in isolated perfused rat heart does not involve direct activation of the CDP-DG pathway

Oleate has been shown previously to stimulate the in vitro activity of phosphatidylglycerol-phosphatase, an important enzyme in the cytidine-5'-diphosphate-1,2-diacyl-sn-glycerol pathway of phosphatidylglycerol and cardiolipin biosynthesis. In this study the in vivo effect of oleate on the biosynthesis of new phosphatidylglycerol and cardiolipin was investigated in the heart. Hearts were perfused for 60 min with Krebs-Henseleit buffer containing [1,3-3H]glycerol and 0.6 mM albumin in the absence or presence of 0.6 or 1.2 mM oleate. Total incorporation of radioactivity was higher in the oleate-treated hearts compared with controls and this was due to an exclusive incorporation of radioactive glycerol into the organic phase. Also, the radioactivity incorporated into phosphatidylglycerol and cardiolipin was higher in the oleate-treated hearts compared with controls; however, the increase was greater in hearts perfused with 0.6 mM oleate compared with 1.2 mM oleate, indicating that pathophysiological concentrations of oleate may attenuate the oleate-induced stimulation of glycerol incorporation into polyglycerophospholipids. The pool size of phosphatidylglycerol and cardiolipin were unchanged in oleate-perfused hearts compared with controls. To investigate if the biosynthesis of phosphatidylglycerol and cardiolipin via the cytidine-5'-diphosphate-1,2-diacyl-sn-glycerol pathway was authentically stimulated by oleate hearts were pulse labeled for 15 min with 0.1 mM [1,3-3H]glycerol and subsequently chased for 60 min with 0.1 mM glycerol in the absence or presence of 0.6 mM oleate in the perfusate. Radioactivity incorporated into phosphatidylglycerol and cardiolipin was unchanged compared with controls. Our data indicate that oleate increases the incorporation of exogenous glycerol into polyglycerophospholipids but not accelerate synthesis from prelabeled precursor pools. Accordingly, oleate does not appear to stimulate directly enzymes of the cytidine-5'-diphosphate-1,2-diacyl-sn-glycerol pathway in vivo.     

Poly(1-vinyl-2-pyrrolidinone) hydrogels as vitreous substitutes: histopathological evaluation in the animal eye

A homopolymer of 1-vinyl-2 pyrrolidinone and its copolymer with 2-hydroxyethyl methacrylate, both cross-linked with divinyl glycol, were produced as possible substitutes for the vitreous body of the eye. The hydrated polymers behaved like viscoelastic gels, displaying excellent physical and optical properties. The sterile gels (0.7-1.5 ml) were injected into the vitreous cavity of rabbits, which previously underwent gas-mediated vitrectomy. Clinically, the eyes were quiet, with the exception of transient opacities in the vitreous. After 4 weeks, the operated eyes were enucleated and subjected to histopathological analysis using light and transmission electron microscopy. The common feature in all sections was the invasion of inflammatory cells. Vacuoles containing granular material, assumed to be polymer, were seen in the intercellular spaces of the neural retina, in the retinal pigment epithelium cells, and in macrophages. These findings indicated the fragmentation and phagocytosis of synthetic gels. It appeared that the biodegradation of the internalized polymers did not proceed further, however, the fate of polymers and their usefulness as vitreous substitutes should be investigated through long-term experiments.     

Hyperplasia of the aorticopulmonary paraganglia: a new insight into the pathogenesis of sudden infant death syndrome?

OBJECTIVE: To study the effect of using an Intensive Care Information System (ICIS) on severity scores and prognostic indices: Acute Physiology and Chronic Health Evaluation II (APACHE II), Simplified Acute Physiology Score II (SAPS II), and Mortality Probability Models II (MPM II). DESIGN: Prospective pilot study. SETTING: A 20-bed medical-surgical intensive care unit (ICU) in a teaching hospital. PATIENTS: 50 consecutive adult patients admitted to the ICU on a bed equipped with an ICIS. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: In each patient all the physiologic variables, as required by the severity scores, were both manually charted and recorded by ICIS. ICIS registration resulted in the extraction of more abnormal values for all physiologic variables (except temperature): p < 0.05. Higher severity scores and mortality prediction were achieved by using ICIS charting: predicted mortality increased by 15% for APACHE II compared to manual charting, 25% for SAPS II, and 24% for MPM0. ICIS charting resulted in higher severity scores and mortality prediction for 29 of the 50 patients using APACHE II with a mean increase in mortality prediction in this subgroup of 27%. In the case of SAPS II, ICIS charting resulted in higher scores in 23 of the 50 patients and in the case of MPM0 in 13 patients, the mean increase in mortality in these subgroups being 64 and 148%, respectively. CONCLUSIONS: The use of ICIS charting to acquire the most abnormal physiologic values for severity scores and the derived prognostic indices results in a higher mortality prediction. Comparison of groups of patients and/or ICUs based on severity scores is impossible without standardization of data collection. The mortality prediction models have to be revalidated for the use of ICIS charting. While awaiting this, we suggest that every patient record in local regional, national, or international ICU databases should be marked as being recorded by manual or by ICIS charting.     

Persistent resetting of the cerebral oxygen/glucose uptake ratio by brain activation: evidence obtained with the Kety-Schmidt technique

Global cerebral blood flow (CBF), global cerebral metabolic rates for oxygen (CMRO2), and for glucose (CMRglc), and lactate efflux were measured during rest and during cerebral activation induced by the Wisconsin card sorting test. Measurements were performed in healthy volunteers using the Kety-Schmidt technique. Global CMRO2 was unchanged during cerebral activation, whereas global CBF and global CMRglc both increased by 12%, reducing the molar ratio of oxygen to glucose consumption from 6.0 during baseline conditions to 5.4 during activation. Data obtained in the period following cerebral activation showed that the activation-induced resetting of the relation between CMRglc and CMRO2 persisted virtually unaltered for > or = 40 min after the mental activation task was terminated. The activation-induced increase in cerebral lactate efflux measured over the same time period accounted for only a small fraction of the activation-induced excess glucose uptake. These data confirm earlier reports that brain activation can induce resetting of the cerebral oxygen/glucose consumption ratio, and indicate that the resetting persists for a long period after cerebral activation has been terminated and physiologic stress indicators returned to baseline values. Activation-induced resetting of the cerebral oxygen/glucose uptake ratio is not necessarily accounted for by increased lactate production from nonoxidative glucose metabolism.     

N-(2-Benzoylphenyl)-L-tyrosine PPARgamma agonists. 3. Structure-activity relationship and optimization of the N-aryl substituent

3-?4-[2-(Benzoxazol-2-ylmethylamino)ethoxy]phenyl?-(2S)-((2- benzoylph enyl)amino)propionic acid (1) and (2S)-((2-benzoylphenyl)amino)-3-?4-[2-(5-methyl-2-phenyloxazol-4-y l)e thoxy]phenyl?propionic acid (2) are peroxisome proliferator-activated receptor gamma (PPARgamma) agonists and have antidiabetic activity in rodent models of type 2 diabetes. As part of an effort to develop the SAR of the N-2-benzoylphenyl moiety of 1 and 2, a series of novel carboxylic acid analogues, 23-66, modified only in the N-2-benzoylphenyl moiety were synthesized from L-tyrosine and evaluated as PPARgamma agonists. In general, only modest changes in the N-2-benzoylphenyl moiety of 1 and 2 are tolerated. More specifically, the best changes involve bioisosteric replacement of one of the two phenyl rings of this moiety. Addition of substituents to this moiety generally produced compounds that are less active in the cell-based functional assays of PPARgamma activity although binding affinity to PPARgamma may be maintained. A particularly promising set of analogues is the anthranilic acid esters 63-66 in which the phenyl ring in the 2-benzoyl group of 1 and 2 has been replaced by an alkoxy group. In particular, (S)-2-(1-carboxy-2-?4-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]phen yl? ethylamino)benzoic acid methyl ester (63) has a pKi of 8.43 in the binding assay using human PPARgamma ligand binding domain and a pEC50 of 9.21 in the in vitro murine lipogenesis functional assay of PPARgamma activity. Finally, 63 was found to normalize glycemia when dosed at 3 mg/kg bid po in the Zucker diabetic fatty rat model of type 2 diabetes.     

Detection of alcohol misusing patients in accident and emergency departments: the Paddington alcohol test (PAT)

The list of hepatitis viruses is increasing over the years. Now the viruses range from A to G. Hepatitis A virus is a short incubation RNA virus which is transmitted oro-faecally. It does not cause chronic illness but may be fatal in a few cases especially in pregnancy. It can now be prevented by vaccination. Hepatitis B virus is a long incubation DNA virus which is transmitted mainly through blood and blood products. It causes chronic illness and can lead to liver cancer in some cases. It can be prevented by vaccination and WHO is now recommending global vaccination of all infants irrespective of endemicity of hepatitis B virus. Hepatitis C virus is an RNA virus which used to be known as parenterally transmitted non A non-B virus. It leads to chronic illness and can lead to liver cancer. It is now responsible for most cases of post transfusion hepatitis in Europe, North America and Asia. Hepatitis Delta virus is a defective virus which requires hepatitis B virus for its existence. Thus it affects only those who have hepatitis B virus. Hepatitis E virus used to be known as the enterically transmitted non-A non-B virus. It is transmitted oro-faecally and seems not to lead to chronic illness. It is endemic in some areas like Middle East and parts of Africa. Hepatitis G virus is just being described. More information about it will soon be available.