Distribution and characterization of natriuretic peptide receptors in the gills of the spiny dogfish, Squalus acanthias

The distribution and nature of natriuretic peptide receptors (NPR) in the gills of dogfish, Squalus acanthias, were examined by tissue section autoradiography, competition analysis, protein electrophoresis, guanylate cyclase (GC) assays, and molecular cloning. Specific NP binding occurred on the gill filaments, but not on the interbranchial septum or gill arch. The binding was densest on the efferent edge of the gills. Higher resolution light-microscopic examination of emulsion-coated sections showed that specific binding occurred mainly on the secondary lamellae and filament body and not on the arterial circulation. At least two types of NPR were revealed. One is linked to GC since NP binding stimulates the production of cGMP. The GC receptor may be similar to the NPR-B mammalian receptor since only pCNP stimulated cGMP production. The second receptor is not linked to GC and binds the specific ligand C-ANF [rat des(Gln18, Ser19, Gly20, Leu21, Gly22)]. The sequence of a cDNA generated using primers based on conserved regions of vertebrate NPR-C had considerable homology with mammalian and eel NPR-C and eel NPR-D. The presence of GC-linked NPR and NPR-C/ NPR-D suggests that the gills are an important target organ for NP action.     

Intestinal permeability to small- and large-molecular-weight substances in the newborn rabbit

BACKGROUND/PURPOSE: The authors have previously reported the occurrence of spontaneous bacterial translocation (BT) and its resolution with age in the newborn rabbit. They have also reported a close correlation between small bowel bacterial colonization (BC-SB) and BT at 1 week of age, suggesting that the presence of luminal bacteria and their production of endotoxins may increase the intestinal permeability. The aim of this study was to evaluate intestinal permeability to small and large molecules in the newborn rabbit and to correlate it with BT. MATERIALS AND METHODS: New Zealand White rabbits (n = 96) 1, 7, 14, 21, and over 120 days (adult) of age were given either C14-labeled ethylene diamine tetraacetic acid (EDTA) (MW 290) or C14-Dextran (MW 70,000) via an orogastric tube at 1 mCi per 100 g of body weight. Five hours later, blood, urine, liver, and intestine were collected, and scintillation counting was performed after solubilization. In a separate series of rabbits (n = 136), the incidence of BT, BC-SB, and small intestinal surface area (SA) were measured. RESULTS: Total permeability to Dextran decreased with age and was significantly reduced at 14 days of age. In contrast, total permeability to EDTA increased and was maximal in 7- to 14-day-old rabbits and began to decrease at 21 days of age. The incidence of BC-SB rapidly increased at 7 days of age and reached 100% at 14 days of age. The incidence of BT peaked at 7 days of life (30%) and then decreased with age. SA increased rapidly in the first 3 weeks and SA growth rate of 21-day-old rabbits was almost 1,400% compared with 1-day-old rabbits. CONCLUSIONS: This study has shown an age-related reduction of intestinal permeability to large (Dextran) and small (EDTA) molecular weight particles. However, intestinal permeability to EDTA had a different pattern than Dextran, suggesting that there may be different mechanisms of intestinal permeability to different size molecules. Intestinal permeability to EDTA closely correlated with bacterial colonization and bacterial translocation, suggesting that changes in the intestinal bacterial environment may affect the intestinal permeability, possibly by activating the immune system secondary to increases in endotoxins and bacteria.     

Proliferation and migration kinetics of stem cells in the rat fundic gland

The proliferation and migration of stem cells in the developing and adult rat fundic gland have been studied using BrdU immunohistochemistry and BrdU-GSA II (Griffonia-simplicifolia agglutinin-II) double staining. In the developing rat fundic gland, stem cells were first scattered throughout all levels of the epithelia and then concentrated in the depth of the pits. With the elongation and maturation of the fundic glands, stem cells left the gland base and moved upward. By 4 weeks after birth, the development of the fundic gland was completed and stem cells were confined to a narrow proliferative zone in the isthmus, reaching the adult distribution pattern. In the adult rat fundic gland, stem cells in the isthmus differentiated and migrated upward and downward, replacing the surface mucous cells and glandular cells respectively. For upward migration, it took about one week for stem cells to migrate from the isthmus to the surface. For downward migration, it took about two weeks for stem cells to migrate from the isthmus to the neck, and it took 30-36 weeks to reach the gland unit's blind end. Finally stem cells were lost at the deepest level of the glands. The results obtained by simple topographical distribution in the present experiment agreed well with those obtained by quantitative analysis, suggesting the usefulness of BrdU immunohistochemistry for cell kinetic studies.     

New pharmacologic strategies for acute neuronal injury

The number of new drugs for treating neurotrauma is rapidly expanding. Emerging theories regarding the mechanisms of secondary neuronal injury provide the scientific basis for evaluating these new agents. Some of the most promising mechanisms for intervention are ionotropic channel antagonism, inhibition of lipid peroxidation, and neurotrophic factor augmentation. Many of these new agents are undergoing clinical trials to establish their roles in therapy.     

Calcium transport by isolated brush border and basolateral membrane vesicles: role of essential fatty acid supplementation

Intestinal calcium transport is important in whole body calcium homeostasis and it is therefore of interest to understand the mechanism of absorption and its regulation by 1;25-dihydroxyvitamin D3 (1,25 (OH)2D3) (vitamin D). Significant changes in lipid composition of membranes have previously been shown in response to vitamin D3 administration. Deficiency in essential fatty acids (EFAs) may influence the vitamin D-dependent calcium absorption in the intestinal tract. The purpose of this study was to investigate the effect of unsaturated fatty acid supplementation on calcium transport. Simultaneous measurements of calcium transport, membrane fluidity and lipid structure have rarely been performed on the same preparation. Intestinal membrane vesicles were prepared using a novel procedure. Vesicles prepared from fish oil and evening primrose oil supplemented animals revealed the highest calcium transport over time as well as the highest degree of unsaturation as compared to those from animals which were unsupplemented or given sunflower or coconut oil. The relative content of polyunsaturated fatty acids in the intestinal membranes may change fluidity, enhance calcium transport and may influence the action of vitamin D3 on calcium absorption.     

Susceptibilities of bacterial isolates from patients with cancer to levofloxacin and other quinolones

The antibacterial activity of levofloxacin was compared with those of ofloxacin and ciprofloxacin against bacterial isolates from patients with cancer. In general, levofloxacin was as active or was twofold more active than ofloxacin and was two- to fourfold less active than ciprofloxacin against most gram-negative pathogens. Against Pseudomonas aeruginosa, ciprofloxacin was the most active agent tested (MIC for 90% of isolates tested, 1.0 microgram/ml). Overall, all three agents had similar activities against gram-positive organisms and were moderately active against methicillin-susceptible Staphylococcus aureus and coagulase-negative staphylococci, Streptococcus species, and Enterococcus species.     

Swelling in the isolated perfused cornea induced by 12(R)hydroxyeicosatetraenoic acid

PURPOSE: To evaluate the effect of 12(R)hydroxyeicosatetraenoic acid (12(R)HETE) on corneal swelling when directly perfused to human and rabbit corneal endothelium. METHOD: Excised rabbit and human corneas were mounted in the in vitro specular microscope and the endothelium was perfused with 12(R)HETE at 10(-5), 10(-6), and 10(-7) mol/l. Both 12(R)HETE and 12(S)HETE were compared at equal molar (10(-6) mol/l) concentrations. The reversal of 12(R)HETE and ouabain corneal swelling was also compared. Endothelial permeability to carboxyfluorescein was measured after 12(R)HETE perfusion. High-performance liquid chromatographic analysis confirmed that 12(R)HETE remained in the perfusion media. RESULTS: 12(R)HETE caused a dose-dependent corneal swelling of 25 +/- 2, 24 +/- 1, and 14 +/- 0.5 microns/hr at 10(-5), 10(-6), and 10(-7) mol/l, respectively. Equal molar concentrations (10(-6) mol/l) of 12(S)HETE did not cause corneal swelling. Removal of the 12(R)HETE from the perfusion media resulted in reversal of corneal swelling whereas corneal swelling induced by ouabain did not reverse after ouabain removal. 12(R)HETE (10(-6) mol/l) perfused to the human corneal endothelium inhibited temperature reversal corneal thinning when compared to the paired corneal endothelium perfused with BSS Plus (Alcon Laboratories, Inc., Fort Worth, TX). Na/K adenosine triphosphatase activity was inhibited by 10(-6) mol/l ouabain by 35%, 10(-6) mol/l 12(R)HETE by 54%, and 10(-6) mol/l 12(S)HETE by 0.5%. Endothelial permeability to carboxyfluorescein was unaffected by 12(R)HETE. CONCLUSION: 12(R)HETE causes corneal swelling by inhibiting endothelial pump function. This inhibition of transport appears to be at least partly mediated by inhibition of endothelial Na/K adenosine triphosphatase.     

Study on experimental parameters for diagnosing ganyang huafeng syndrome of cerebral infarction

One hundred patients with cerebral infarction were observed, the results showed that Ganyang Huafeng Syndrome (GYHFS) was the major syndrome of acute cerebral infarction which was accounted for 60% and Qiyin Liangxu Syndrome (QYLXS), Qixu Xueyu Syndrome (QXXYS) were mainly observed at convalescent stage of this disease which was accounted for 37.78% and 31.11% respectively. This study chose plasma norepinephrine (NE), epinephrne (E), thromboxane B2(TXB2), 6-keto-PGF1 alpha, cortisol (F) and serum triiodothyroidoglobulin (T3) as the monitoring parameters, and the results showed that the increase of plasma NE,F,TXB2, the decrease of serum T3 could be considered as the comprehensive experimental parameters for diagnosing GYHFS of cerebral infarction.