Chloroquine-induced venodilation in human hand veins

OBJECTIVE: Hypotension induced by parenteral administration of chloroquine is a common and serious adverse effect of this drug. Our aim was to investigate whether chloroquine produces venodilation in vivo and to explore the underlying mechanisms. METHODS: Vascular effects of chloroquine were studied in healthy volunteers with use of the dorsal hand vein technique at the Geriatric Research Education and Clinical Center, Veterans Affairs Palo Alto Health Care System. We studied 22 healthy volunteers (19 men and three women). Venous responsiveness was determined with the dorsal hand vein technique, which measures the diameter of the vein. RESULTS: Chloroquine was found to produce a dose-dependent relaxation of hand veins preconstricted with the alpha 1-receptor selective agonist phenylephrine. The venodilatory response to chloroquine ranged from 15% +/- 19% at an infusion rate of 0.75 microgram/min to 61% +/- 24% at 48 microgram/min. Venodilation was attenuated by the nitric-oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) so that the dose of chloroquine required to produce 20% venodilation was increased from 3.7 micrograms/min to 15 micrograms/min (p < 0.01). In the presence of a combination of histamine receptor antagonists, there was also a diminution of the vasodilatory response to chloroquine from 72% +/- 5% to 44% +/- 5% at the infusion rate of 96 micrograms/min. The response was further reduced to 33% +/- 7% by the coinfusion of H1-/H2-receptor antagonists with L-NMMA. CONCLUSION: Chloroquine produces venodilation at infusion rates that achieve local concentrations likely similar to those observed systemically after clinically relevant intravenous doses. The date also suggest a role for nitric oxide and histamine release in mediating this response.     

CD45 tyrosine phosphatase activity and membrane anchoring are required for T-cell antigen receptor signaling

T cells that lack the CD45 transmembrane tyrosine phosphatase have a variety of T-cell receptor (TCR) signaling defects that are corrected by reexpression of wild-type CD45 or its intracytoplasmic domains. In this study, a chimeric molecule containing the myristylation sequence of Src and the intracellular portion of CD45, previously shown to restore function in CD45- T cells, was mutagenized to determine if membrane-associated CD45 tyrosine phosphatase activity is required to restore TCR-mediated signaling in CD45- T cells. Abolition of enzymatic activity by substitution of a serine for a critical cysteine in the first catalytic domain resulted in failure of this molecule to restore TCR signaling. Another mutation, in which a single amino acid substitution destroyed the myristylation site, resulted in failure of the chimeric molecule to partition to the plasma membrane. Although expressed at high levels and enzymatically active, this form of intracellular CD45 also failed to restore normal signaling in CD45- T cells. These findings strongly suggest that CD45's function in TCR signaling requires its proximity to membrane-associated tyrosine phosphatase substrates.     

Recognition of phage-expressed peptides containing Asx-Pro sequences by monoclonal antibodies produced against Plasmodium falciparum circumsporozoite protein

The immunodominant region of the Plasmodium falciparum circumsporozoite protein is comprised mainly of a series of tetrapeptide repeats that can, depending on the starting cadence chosen, be described as (NANP)n, (ANPN)n, (NPNA)n or (PNAN)n in one-letter amino acid code. Data from several studies suggest that the NPNA cadence alone is structurally correct, in that each NPNA tetrapeptide effectively forms a structural unit initiated by an Asx-Pro turn. To explore this idea further and to assess the immunological relevance of peptide conformation as it relates to the cadence of these tetrapeptide repeats, we used ELISA to compare the abilities of monoclonal antibodies (MAbs) produced against P. falciparum sporozoites to recognize repeat-related heptapeptides expressed on the surface of filamentous bacteriophage. Having included representatives of both NANP and NPNA cadences and other peptides in which the number and location of Asx-Pro sequences varied, we provide evidence that Asx-Pro sequences play an important role in peptide conformation and antibody recognition, that peptide conformation is influenced by the cadence of the tetrapeptide repeats and that peptide conformation is important to the abilities of these MAbs to recognize their epitopes.      

腐植酸作为天然有机物(NOM)的主要类型对环糊精聚氨酯去除水中异味的影响

目前,水处理机构普遍认为,天然有机物会妨碍活性炭的吸附位点与异味化合物结合,进而导致对甲萘烷醇和2-甲基异茨醇的清除效率下降。腐植酸也被认为具有相同的作用。对于城市水处理系统来说,饮用水中异味化合物如甲萘烷醇和2-甲基异茨醇的清除至关重要。已证实,环糊精聚氨酯可清除水中有机污染物,但不会显著降低天然有机物的含量。我们希望确定在有天然有机物存在的条件下,该聚合物是否能够有选择地去除甲萘烷醇和2-甲基异茨醇。本研究以腐植酸为天然有机物代表,因腐植酸约占天然有机物的70%。研究表明,不同浓度腐植酸的存在不会影响甲萘烷醇和2-甲基异茨醇的清除,使用环糊精聚合物,90%的异味化合物被去除。同时,紫外分析表明只有少量的腐植酸(3%～20%)被去除。     

Homologues of the Cf-9 disease resistance gene (Hcr9s) are present at multiple loci on the short arm of tomato chromosome 1

The tomato Cf-4 and Cf-9 genes map at a genetically complex locus on the short arm of chromosome 1 and confer resistance against Cladosporium fulvum through recognition of different pathogen-encoded avirulence determinants. Cf-4 and Cf-9 are members of a large gene family (Hcr9s, Homologues of Cladosporium fulvum resistance gene Cf-9), some of which encode additional distinct recognition specificities. A genetic analysis of the majority of Hcr9s suggests that their distribution is spatially restricted to the short arm of chromosome 1. Two loci of clustered Hcr9 genes have been analyzed physically that mapped distal (Northern Lights) and proximal (Southern Cross) to the Cf-4/9 locus (Milky Way). Sequence homologies between intergenic regions at Southern Cross and Milky Way indicate local Hcr9 duplication preceded cluster multiplication. The multiplication of clusters involved DNA flanking Hcr9 sequences as indicated by conserved lipoxygenase sequences at Southern Cross and Milky Way. The similar spatial distribution of Hcr9 clusters in different Lycopersicon spp. suggests Hcr9 cluster multiplication preceded speciation.     

Mice expressing human but not murine beta3-adrenergic receptors under the control of human gene regulatory elements

Beta-adrenergic receptors (ARs) are expressed predominantly in adipose tissue, and beta3-selective agonists are effective anti-obesity drugs in rodents. Rodent and human beta3-ARs differ with respect to expression in white versus brown adipocytes as well as their ability to be stimulated by beta3-AR-selective agonists. Humans express beta3-AR mRNA abundantly in brown but not white adipocytes, while rodents express beta3-AR mRNA abundantly in both sites. To determine the basis for this difference, we have transgenically introduced 74 kilobases (kb) of human beta3-AR genomic sequence into gene knockout mice lacking beta3-ARs. Importantly, human beta3-AR mRNA was expressed only in brown adipose tissue (BAT) of transgenic mice, with little or no expression being detected in white adipose tissue (WAT), liver, stomach, small intestine, skeletal muscle, and heart. This pattern of expression differed from that observed in mice bearing a murine beta3-AR genomic transgene in which beta3-AR mRNA was expressed in both WAT and BAT, but not in other sites. Furthermore, we have transgenically introduced smaller human constructs containing -14.5 and -0.6 kb of upstream sequence into beta3-AR gene knockout mice. Both -14.5 and -0.6 kb constructs were expressed in BAT but not WAT. Thus, human but not murine cis-regulatory elements direct beta3-AR gene expression preferentially to brown adipocytes. Identification of responsible cis-regulatory element(s) and relevant trans-acting factor(s) should provide insight into mechanisms controlling human beta3-AR gene expression. In addition, the beta3-AR agonist, CGP-12177, stimulated oxygen consumption in mice expressing human but not murine beta3-ARs by 91% compared with only 49% in control beta3-AR gene knockout mice, demonstrating that the human beta3-AR can functionally couple with energy expenditure. These "humanized" mice should assist us in the development of drugs that may become effective anti-obesity agents in humans.     

Descriptive epidemiology of thyroid cancer in greater Bombay

Idiopathic varicocele can compromise the spermatogenetic function of the testicle and associate with alterations of the semen quality. The treatment of varicocele stops the progress of testicular damage and improves spermatogenesis and semen parameters. These are the main alternatives to the traditional surgical treatment of varicocele retrograde percutaneous occlusion of the internal spermatic vein using sclerosing agents and embolizing devices (either separately or in combination), microsurgical ligation via inguinal or sub-inguinal approach, laparoscopic ligation and, more recently, antegrade scrotal sclerotherapy. None of these techniques can be considered the "gold standard" therapy. Literature does not point out any significant difference between them, either considering the absence of reflux percentage, or the improvement of semen quality, or the pregnance rate. Therefore cost comparison may be a valid criterion in the choice of treatment for varicocele correction. The total cost of the surgical retroperitoneal unilateral ligation of the internal spermatic vein is 968,805 Lire, while for the bilateral ligation it is 1,118,285 Lire. The costs of sclerotherapy and percutaneous embolization are respectively of 698,750 Lire and 1,708,950 Lire. The combination of the two techniques amounts to 1,918,230 Lire. Laparoscopic bilateral ligation costs 2,437,935 Lire. Antegrade scrotal sclerotherapy costs 191,035 Lire if unilateral, 216,580 Lire if bilateral. After considering these data we can say that antegrade scrotal sclerotherapy is the first choice economically in the treatment of both unilateral and bilateral varicocele.     

Glucoamylase mutants in the conserved active-site segment Trp170-Tyr175 located at a distance from the site of catalysis

To mimic the structure of the 1.8-fold more active (k(cat)) Rhizopus oryzae glucoamylase (GA), Aspergillus niger GA was subjected to site- directed mutagenesis in the Trp170-Tyr175 segment of the third of the six well-conserved alpha-->alpha connecting loops of the catalytic (alpha/alpha)6-barrel. While the Trp170-->Phe, Gln172-->Asn and Tyr175-- >Phe mutants showed an up to 1.7-fold increased k(cat) and Gly174-->Cys GA and approximately 2-fold reduced k(cat) towards maltotriose and longer substrates, Asn171-->Ser, Thr173-->Gly and A.niger wild-type GA had very similar kcat and K(m) values for the hydrolysis of isomaltose and the malto-oligosaccharides of DP 2-7. Crystal structures of pseudotetrasaccharide inhibitor complexes of Aspergillus awamori var. X100 GA, which is 94% identical to A.niger GA, indicate that Tyr175 is located at binding subsite 4, while the preceding target residues and the high-mannose type unit on Asn171 are at a larger distance from the site of catalysis. The mutations had a modest effect on thermostability; the temperature for 50% inactivation, Tm, was thus unchanged for Tyr175 -->Phe GA and reduced by 0.2-2.9 degrees C for the other mutants. The deletion of the N-linked high-mannose unit-in Asn171 -->Ser and Thr173-->Gly GAs-appeared to be of minor importance for enzyme activity and thermostability, and did not increase the sensitivity to proteolysis.