Comparison of mismatch amplification mutation assay with DNA sequencing for characterization of fluoroquinolone resistance in Neisseria gonorrhoeae

A mismatch amplification mutation assay (MAMA) was developed for identification of point mutations in quinolone resistance-determining region (QRDR) of gyrA at codons 91 and 95. MAMA PCR was used to detect mutations at codons 91 and 95 of gyrA in 117 Neisseria gonorrhoeae isolates (with ciprofloxacin MICs of 0.004 to >32 microg/ml) from Bangladesh during 1997 to 2001. The QRDR regions of the gyrA genes from 31 randomly selected isolates were sequenced, and the results were compared with those of MAMA PCR. Using mismatch PCR, a mutation at Ser91 could be detected in all 27 (resistant and intermediate) isolates, and an Asp95-to-Gly95 mutation could be detected in all 15 isolates, as detected by sequencing. MAMA PCR offers a simple, inexpensive, rapid, and easier alternative for detection of point mutations in fluoroquinolone resistance in N. gonorrhoeae.     

The immediate early genes of human cytomegalovirus require only proximal promoter elements to upregulate expression of interleukin-1 beta.

Human cytomegalovirus (HCMV) can infect monocytes and macrophages. The immediate early one (IE1) gene product of HCMV positively regulates its own expression, as well as the expression of the interleukin-1 beta (IL-1) gene. This study describes the IL-1 promoter proximal region required for upregulation of IL-1 gene expression by the HCMV IE1 or IE1 plus IE2 gene products. An IL-1 chloramphenicol acetyltransferase (CAT) construct containing the IL-1 genomic upstream sequence from position -1097 to +14 and four additional IL-1CAT plasmids containing progressive deletions of the -1097 to -131 sequence were used to evaluate the effect of the HCMV IE gene products on IL-1 gene expression. IL-1CAT plasmids were transfected into a monocytic cell line, THP-1, with plasmids containing either the IE promoter-regulatory region upstream of the bona fide IE1 (pIE1), IE2 (pIE2), or IE1+2 genes (pIE1+2) or a control plasmid containing the IE promoter-regulatory region alone (pLink760). In the presence of pIE1+2, there was an approximate 15-fold increase in CAT activity compared with the control, pLink760, in cells with CAT plasmids containing the -1097 to +14 IL-1 sequence. Plasmids with progressive deletions of this sequence, including the plasmid containing the shortest upstream segment (-131 to +14) also had an approximate 15-fold increase in CAT activity. The upregulation of IL-1 expression was mediated, primarily, by IE1 and not by IE2. This effect was promoter specific because an IL-1CAT plasmid with a complete deletion of the proximal promoter elements (-234 to +146) did not respond to the HCMV IE gene products.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lassa fever. Effective therapy with ribavirin

In a study of Lassa fever in Sierra Leone, West Africa, we identified two variables associated with a high risk of death, and we evaluated the efficacy of ribavirin and Lassa virus-convalescent plasma for the treatment of Lassa fever. A serum aspartate aminotransferase level greater than or equal to 150 IU per liter at the time of hospital admission was associated with a case-fatality rate of 55 percent (33 of 60). Patients with the same risk factor who were treated for 10 days with intravenous ribavirin, begun within the first 6 days after the onset of fever, had a case-fatality rate of 5 percent (1 of 20) (P = 0.0002 by Fisher's exact test). Patients whose treatment began seven or more days after the onset of fever had a case-fatality rate of 26 percent (11 of 43) (P = 0.01). Viremia with levels greater than or equal to 10(3.6) TCID50 per milliliter on admission was associated with a case-fatality rate of 76 percent (35 of 46). Patients with this risk factor who were treated with intravenous ribavirin within the first six days after onset of fever had a case-fatality rate of 9 percent (1 of 11) (P = 0.006), whereas those treated after seven days or more of illness had a fatality rate of 47 percent (9 of 19) (P = 0.035). Oral ribavirin was also effective in patients at high risk of death. Lassa-convalescent plasma did not significantly reduce mortality in any of the high-risk groups. We conclude that ribavirin is effective in the treatment of Lassa fever and that it should be used at any point in the illness, as well as for postexposure prophylaxis.     

Serum estradiol concentration required to maintain body weight, attractivity, proceptivity, and receptivity in the ovariectomized female rat

Female hooded rats (230 to 260 g) were ovariectomized and given a subcutaneous implant of an estradiol-filled Silastic tube. The length of the tube was varied in order to produce a variety of serum estradiol levels. In the first experiment, animals were weighed over a 6-week period following surgery and then tested for sexual responsiveness to a male. The results demonstrated that ovariectomized females with an implant maintaining a serum estradiol concentration at about 15 pg/ml maintained body weight at the same level as that of intact females. A smaller implant gave rise to a higher weight gain and a larger implant to a lower weight gain. All implants resulted in a continuous state of receptivity. In a second experiment, ovariectomized females were implanted with smaller estradiol-filled implants in order to determine the threshold for maintaining proceptivity and receptivity. The results indicated that with a serum estradiol concentration below 15 pg/ml, the frequency of lordosis and of ear wiggling and darting decreased. Progesterone injections facilitated both proceptive and receptive behavior. In addition, following progesterone injections, the time required for a male to mount a female 10 times was decreased in females with low or no estradiol replacement. These results indicate that a constant concentration of estradiol at about the mean level present throughout the estrous cycle will result in normal body weight regulation and will maintain sexual behaviors that normally occur only during estrus. These results emphasize that Silastic implants of estradiol do not mimic normal endocrine function since, even at low levels, estradiol implants produce continuous receptivity.     

Radioimmunoassay of detirelix ([ N-Ac-D-Nal(2)1,D-p-Cl-Phe2,D-Trp3, D-hArg(Et)6(2),D-Ala10]-luteinizing hormone-releasing hormone) in plasma or serum

A procedure for the radioimmunoassay (RIA) of detirelix in plasma or serum at concentrations as low as 0.15 ng/ml is described. Antiserum was produced by deacetylation of the N-terminus amino groups of detirelix and coupling this analog to bovine serum albumin with a carbodiimide and immunizing rabbits with the resultant conjugate. For RIA, 125I-labeled detirelix was used as the tracer and a double antibody procedure was used to separate the free and bound fractions. No purification of samples was required prior to RIA. Accuracy of the method was assessed by adding known quantities of detirelix to detirelix-free plasma and determining the ratio of measured to added analyte. Linear regression analysis for the concentration range 0.15-150.0 ng/ml yielded a regression equation of y = 0.88 X +1.46 and a correlation coefficient of 0.996. Additional validation was obtained from an in vivo study in which [14C]detirelix was administered to monkeys and plasma clearance profiles were determined by RIA and an HPLC-radiochemical method. The RIA results were in good agreement with those obtained by the HPLC method.     

Evidence for a calcium regulated, bidirectional intronic promoter in the murine TCR V{alpha}1 gene

Previous studies of the TCR chain gene have located promoterelements 5' to the start of the various V genes. The only fullycharacterized enhancer for the entire chain gene (V, J andC genes) has been located {small tilde}3 kb from the 3' endof C. We now report the existence of additional regulatory elementslocated in the introns of several murine V genes (V1, V3 andVB6.2.16). In the case of V1, this element appears to be a promoterwith bidirectional activity that is not T cell specific. Interestingly,upstream of the promoter in the antisense strand, an open readingframe has been found that codes for a small molecular weightprotein ({small tilde}60 amino acids) that contains a prollne-richregion and a tyrosine-isoleucine motif that has homology toIgß (the B29 gene product). A rabbit antiserum madeagainst this sequence has confirmed its existence by Westernblot and immunoprecipitation. Thus this V1 intronic promoterhas the potential not only to induce the formation of a truncatedV1 gene product, but also regulates the expression of a smallmolecular weight protein that may be involved in lymphocyteantigen receptor signaling. The activity of this promoter isregulated by changes in intracellular calcium. In the presenceof ionomycin the promoter is down-regulated in the sense directionand its activity is enhanced in the antisense direction. Thisresult suggests that this promoter can act differentially toproduce two very different gene products. The bidirectionalV1 promoter appears to be the first in the Ig superfamily toinduce potentially functional proteins in both directions.     

Relationship of glucocorticoid suppression of arachidonic acid metabolism to alteration of neutrophil function

The role of arachidonic acid metabolism in glucocorticoid-induced suppression of neutrophil function was investigated. In vivo treatment of cattle with dexamethasone decreased the production of lipoxygenase products of arachidonic acid metabolism (leukotriene B4 [LTB4] and H-5-hydroxy-6,8,11,14-eicosatetraenoic acid [5-HETE]) in neutrophils. We previously reported that in vivo dexamethasone treatment resulted in alteration of in vitro neutrophil oxidative metabolism, iodination, antibody-dependent cell-mediated cytotoxicity (ADCC), and random migration. To determine if the decrease in production of LTB4 and 5-HETE were responsible for the changes in neutrophil function, neutrophils were treated in vitro with inhibitors of the lipoxygenase enzyme (BW755c and nordihydroguaiaretic acid), and their function was evaluated. A decrease in neutrophil oxidative metabolism and iodination was observed, but there was no effect on neutrophil random migration or ADCC. The results suggest that in vivo treatment with glucocorticoids inhibit neutrophil oxidative metabolism and iodination by decreasing the formation of lipoxygenase products of arachidonic acid metabolism but alter neutrophil random migration and ADCC by a mechanism independent of arachidonic acid metabolism.     

Relapsing diabetes can result from moderately activating mutations in KCNJ11

Neonatal diabetes can either remit and hence be transient or else may be permanent. These two phenotypes were considered to be genetically distinct. Abnormalities of 6q24 are the commonest cause of transient neonatal diabetes (TNDM). Mutations in KCNJ11, which encodes Kir6.2, the pore-forming subunit of the ATP-sensitive potassium channel (K(ATP)), are the commonest cause of permanent neonatal diabetes (PNDM). In addition to diabetes, some KCNJ11 mutations also result in marked developmental delay and epilepsy. These mutations are more severe on functional characterization. We investigated whether mutations in KCNJ11 could also give rise to TNDM. We identified the three novel heterozygous mutations (G53S, G53R, I182V) in three of 11 probands with clinically defined TNDM, who did not have chromosome 6q24 abnormalities. The mutations co-segregated with diabetes within families and were not found in 100 controls. All probands had insulin-treated diabetes diagnosed in the first 4 months and went into remission by 7-14 months. Functional characterization of the TNDM associated mutations was performed by expressing the mutated Kir6.2 with SUR1 in Xenopus laevis oocytes. All three heterozygous mutations resulted in a reduction in the sensitivity to ATP when compared with wild-type (IC(50) approximately 30 versus approximately 7 microM, P-value for is all <0.01); however, this was less profoundly reduced than with the PNDM associated mutations. In conclusion, mutations in KCNJ11 are the first genetic cause for remitting as well as permanent diabetes. This suggests that a fixed ion channel abnormality can result in a fluctuating glycaemic phenotype. The multiple phenotypes associated with activating KCNJ11 mutations may reflect their severity in vitro.     

Frequency and replication status of the fragile X, fra(X)(q27-28), in a pair of monozygotic twins of markedly differing intelligence.

Chromosome analysis using conventional staining, G banding, and, after BUdR incorporation, two R banding methods, one using Hoechst and one acridine orange, were performed on lymphocytes from a pair of female monozygotic twins. The culture conditions were designed to show the presence of the fragile X (q27-28) which had previously been found to be segregating in the family. One twin was of higher than normal intelligence and the other had been diagnosed as mentally retarded. The frequency of the occurrence of the early/active fragile X compared to the overall total of informative fragile X was determined using both methods described above and was also compared with previous published data in the form of a graph showing percentage of early/active fragile X against intelligence.     

Identification of multidrug-resistant Streptococcus pneumoniae strains isolated in Poland by multilocus sequence typing

Multilocus sequence typing (MLST) of 35 isolates of multidrug-resistant Streptococcus pneumoniae recovered in Poland during 1995-1996 distinguished 10 different sequence types (ST). The majority of the isolates were assigned to two Polish clones of serotypes 6B and 23F, although the international clones, Spain23F-1 and Spain9V-3, were also identified. Similar results were obtained using pulsed-field gel electrophoresis (PFGE), providing a direct comparison of these two typing methods.