Detection of expression of influenza virus receptors in tissues of BALB/c mice by histochemistry.

Infection of host cells with the influenza virus is mediated by specific interactions between the viral hemagglutinin and its cell receptor, oligosaccharides containing sialic acid (SA) residues. Avian and human influenza viruses preferentially bind to α-2, 3-linked and α-2, 6-linked sialic acids, respectively. Therefore, differential expression of these receptors may be crucial to influenza virus infection. To date, the distribution of these two receptors has never been investigated in the tissues of BALB/c mice, which is the routine animal model for influenza research. Here, the expression pattern of alpha-2,3 and alpha-2,6 sialic acid-linked receptors in various organs (respiratory tract, gastrointestinal tract, brain, cerebellum, spleen, liver, kidney and heart) of BALB/c mice were determined. Histochemical staining of mouse tissue sections was performed by using biotinylated Maackia amurensis lectin II (MAAII), and Sambucus nigra agglutinin (SNA) were performed to detect the alpha-2,3 and alpha-2,6 sialic acid-linked receptors, respectively. The results showed that the alpha-2,3 and alpha-2,6 sialic acid-linked receptors were both expressed on trachea, lung, cerebellum, spleen, liver and kidney. Only the epithelial cells of cecum, rectum and blood vessels in the heart express the alpha-2,6 sialic acid-linked receptors. The distribution patterns of the two receptors may explain why this model animal can be infected by the AIV and HuIV and the pathological changes when infection occurred. These data can account for the multiple organ involvement observed in influenza infection and should assist investigators in interpreting results obtained when analyzing AIV or HuIV in the mouse model of disease.

Significance of melatonin in antioxidative defense system: reactions and products.

Melatonin is a potent endogenous free radical scavenger, actions that are independent of its many receptor-mediated effects. In the last several years, hundreds of publications have confirmed that melatonin is a broad-spectrum antioxidant. Melatonin has been reported to scavenge hydrogen peroxide (H(2)O(2)), hydroxyl radical (HO(.)), nitric oxide (NO(.)), peroxynitrite anion (ONOO(-)), hypochlorous acid (HOCl), singlet oxygen ((1)O(2)), superoxide anion (O(2)(-).) and peroxyl radical (LOO(.)), although the validity of its ability to scavenge O(2)(-). and LOO(.) is debatable. Regardless of the radicals scavenged, melatonin prevents oxidative damage at the level of cells, tissues, organs and organisms. The antioxidative mechanisms of melatonin seem different from classical antioxidants such as vitamin C, vitamin E and glutathione. As electron donors, classical antioxidants undergo redox cycling; thus, they have the potential to promote oxidation as well as prevent it. Melatonin, as an electron-rich molecule, may interact with free radicals via an additive reaction to form several stable end-products which are excreted in the urine. Melatonin does not undergo redox cycling and, thus, does not promote oxidation as shown under a variety of experimental conditions. From this point of view, melatonin can be considered a suicidal or terminal antioxidant which distinguishes it from the opportunistic antioxidants. Interestingly, the ability of melatonin to scavenge free radicals is not in a ratio of mole to mole. Indeed, one melatonin molecule scavenges two HO. Also, its secondary and tertiary metabolites, for example, N(1)-acetyl-N(2)-formyl-5-methoxykynuramine, N-acetyl-5-methoxykynuramine and 6-hydroxymelatonin, which are believed to be generated when melatonin interacts with free radicals, are also regarded as effective free radical scavengers. The continuous free radical scavenging potential of the original molecule (melatonin) and its metabolites may be defined as a scavenging cascade reaction. Melatonin also synergizes with vitamin C, vitamin E and glutathione in the scavenging of free radicals. Melatonin has been detected in vegetables, fruits and a variety of herbs. In some plants, especially in flowers and seeds (the reproductive organs which are most vulnerable to oxidative insults), melatonin concentrations are several orders of magnitude higher than measured in the blood of vertebrates. Melatonin in plants not only provides an alternative exogenous source of melatonin for herbivores but also suggests that melatonin may be an important antioxidant in plants which protects them from a hostile environment that includes extreme heat, cold and pollution, all of which generate free radicals.

Identification of highly elevated levels of melatonin in bone marrow: its origin and significance.

Bone marrow is an important tissue in generation of immunocompetent and peripheral blood cells. The progenitors of hematopoietic cells in bone marrow exhibit continuous proliferation and differentiation and they are highly vulnerable to acute or chronic oxidative stress. In this investigation, highly elevated levels of the antioxidant melatonin were identified in rat bone marrow using immunocytochemistry, radioimmunoassay, high performance liquid chromatography with electrochemical detection and mass spectrometry. Night-time melatonin concentrations (expressed as pg melatonin/mg protein) in the bone marrow of rats were roughly two orders of magnitude higher than those in peripheral blood. Measurement of the activities of the two enzymes (N-acetyltransferase (NAT) and hydroxyindole-O-methoxyltransferase (HIOMT)) which synthesize melatonin from serotonin showed that bone marrow cells have measurable NAT activity, but they have very low levels of HIOMT activity (at the one time they were measured). From these studies we could not definitively determine whether melatonin was produced in bone marrow cells or elsewhere. To investigate the potential pineal origin of bone marrow melatonin, long-term (8-month) pinealectomized rats were used to ascertain if the pineal gland is the primary source of this antioxidant. The bone marrow of pinealectomized rats, however, still exhibited high levels of melatonin. These results indicate that a major portion of the bone marrow's melatonin is of extrapineal origin. Immunocytochemistry clearly showed a positive melatonin reaction intracellularly in bone marrow cells. A melatonin concentrating mechanism in these cells is suggested by these findings and this may involve a specific melatonin binding protein. Since melatonin is an endogenous free radical scavenger and an immune-enhancing agent, the high levels of melatonin in bone marrow cells may provide on-site protection to reduce oxidative damage to these highly vulnerable hematopoietic cells and may enhance the immune capacity of cells such as lymphocytes.

Suppression of oxygen toxicity by melatonin.

Melatonin, the chief secretory product of the pineal gland, was recently found to be a free radical scavenger and antioxidant. While most studies to date have used pharmacological quantities of melatonin to limit oxidative damage, physiologic concentrations of the indole which are present in aerobic organisms have also been shown to resist molecular damage inflicted by free radicals. Melatonin has several functions in terms of its antioxidative ability. It readily scavenges the most highly toxic free radical, the hydroxyl radical, and it directly detoxifies the peroxynitrite anion, nitric oxide, singlet oxygen, and the peroxyl radical. Precisely how efficient melatonin is in neutralizing each of these toxic agents remains to be determined. Melatonin also may stimulate several antioxidative enzymes including superoxide dismutase, glutathione peroxidase, and glutathione reductase as well as inhibiting the pro-oxidative enzyme, nitric-oxide synthase. Finally, melatonin chelates transition metal ions and prevents the deterioration of cellular membranes. This combination of actions may all contribute to melatonin's ability to reduce oxidative damage. Melatonin is highly effective in reducing nuclear DNA damage and membrane lipid destruction due to toxic free radicals in vivo. These findings have implications for disease processes, eg, neurodegenerative and cardiovascular diseases, which involve free radicals and for aging itself, which also is believed to be related to accumulated oxidative damage.

[COPU regimen in the treatment of 35 esophageal cancers].

Thirty-five consecutive esophageal cancer patients were treated by a combination regimen COPU (CTX 600-800 mg/m2, IV, on days 1, 8, 15 at 8 PM; VCR 1.4 mg/m2, IV, on days 1, 8, 15, at 8 AM; PDD 30-40 mg/m2, IV drip on days 2, 3; UFT 4#, tid, PO. for three weeks; three weeks as a cycle and 2 cycles as a course) in our hospital from 1986 to 1987. The treatment results showed that 23 (65.7%) gave PR, 3 (8.6%) MR, 8 (22.8%) no change and 1 (2.9%) progressing. The overall response rate (CR + PR) was 65.7%. The toxicity and side effects were analyzed. The data show that COPU regimen is one of the satisfactory first line combination chemotherapy regimens at present in the management of esophageal cancer.

Spectrophotometric determination of chromium in waste water and soil.

The reaction of Cr(VI) with o-nitrophenylfluorone (NPF) in presence of cetyltrimethyl-ammonium bromide (CTMAB) to form a purplish red complex at pH 4.7-6.6 by heating at 50 degrees for 10 min has been investigated. The composition of the complex is 1:2:2 [Cr(VI):NPF:CTMAB], the wavelength of maximum absorbance is 582 nm. The molar absorptivity is 1.11 x 10(5)1.mole(-1).cm(-1). Beer's law is obeyed up to 0.2 microg ml Cr(VI) concentration. The interference of several ions, including Cu(2+), Fe(3+) and Al(3+), is eliminated by addition of a masking mixture containing KF, DCTA and tartrate. A new sensitive method for determination of chromium in waste water and soil is presented.

Spectrophotometric determination of trace amounts of cadmium and zinc in waste water with 4-(2-pyridylazo)-resorcinol and mixed ionic and non-ionic surfactants.

A spectrophotometric method for determination of trace amounts of cadmium and zinc in waste water with PAR and mixed ionic and non-ionic surfactants is described. The interferences of foreign ions can be eliminated by masking with a mixture of triethanolamine, potassium fluoride, ethylenediamine and sodium hexametaphosphate. By virtue of the difference between the absorbances before and after addition of a little sodium diethyldithiocarbamate, cadmium and zinc can be determined directly in aqueous solution without separation. Beer's law is obeyed for 0-20 microg of Cd or 0-12 microg of Zn in 25 ml of solution. The apparent molar absorptivities at 505 nm are 8.65 x 10(4) l.mole(-1).cm(-1) for Cd and 8.21 x 10(4) l.mole(-1).cm(-1) for Zn. Results obtained by applying the proposed method to waste-water samples agree well with those obtained by atomic-absorption spectrophotometry.