Listeriosis in second trimester of pregnancy: case report from India

Although Listeria monocytogenes infection occurs in sporadic and epidemic forms throughout the world, there are certain countries (especially Asian countries) that have reported only a few cases or failed to report even a single case. During her third visit at 17(+5) weeks of gestation, a 22-year-old primigravida presented with the complaint of an acute painful abdomen, leaking per vaginum and low-grade fever for the 2 preceding days. On ultrasonography, a single live fetus with no amniotic fluid was seen and the pregnancy was therefore terminated. L. monocytogenes was isolated from a high vaginal swab.     

Altering heparin cofactor II at VAL439 (P6) either impairs inhibition of thrombin or confers elastase resistance

Heparin cofactor II (HCII) is plasma glycoprotein and thrombin inhibitor of the serpin type previously shown to inhibit thrombin in the absence of its N-terminal 74 amino acids, and to be cleaved by neutrophil elastase (NE) at two sites: I66-F67 and V439-G440, the P6-P5 bond of the reactive center loop. We examined the contribution of Val439 to the reaction of HCII with thrombin and NE. Hexahistidine-tagged HCII proteins lacking residues 1-66 (H6delta66HCII) containing either the wild-type Val 439 or one of six substitutions were-expressed in E. coli. The rates of heparin-catalyzed thrombin inhibition of the V439L, C, or R variants were reduced at least 80-fold compared to wild-type H6delta66HCII, while those of the F, S, or W variants were largely unchanged. Following controlled exposure to NE in the presence of heparin, these latter variants retained 3.5- to 4.5-fold more residual anti-thrombin activity than wild-type H6delta66HCII treated in the same manner. This resistance arose due to deflection of NE attack from V439-G440 to secondary sites. The F, S, or W V439 variants exhibited a similar or greater degree of NE resistance when re-expressed as full-length hexahistidine-tagged HCII proteins, suggesting that the I66-F67 NE site is not well recognized in non-glycosylated HCII. Of these full-length variants, the V439F was the most active, exhibiting only a 2-fold reduction in its heparin-catalyzed rate of thrombin inhibition. HCII can therefore be made NE-resistant without severely compromising its capacity to inhibit thrombin.     

Cellular Pharmacology of Fludarabine Triphosphate in Chronic Lymphocytic Leukemia Cells During Fludarabine Therapy

The pharmacology of fludarabine triphosphate (F-ara-ATP) in leukemic lymphocytes was studied during a phase II trial of fludarabine in 24 patients with chronic lymphocytic leukemia (CLL). Fludarabine was given as a 30-min i.v. infusion at a dose of 25 or 30 mg/m² daily for 5 days. The concentrations of F-ara-ATP, the active metabolite of fludarabine, were determined in leukemic lymphocytes at intervals up to 24 hr after the first infusion. A median peak concentration of 19 μM (range, 6-52 μM) was generally reached 4hr after the beginning of the infusion. No significant relationship was observed between clinical response and the median peak level of F-ara-ATP or the retention of F-ara-ATP in leukemic lymphocytes. In vitro incubation of CLL cells with the parent nucleoside of fludarabine, arabinosyl-2-fluoroadenine (F-ara-A), indicated that F-ara-ATP accumulated in a linear fashion in response to the product of the F-ara-A concentration times the duration of incubation. Exposing cells longer with lower F-ara-A concentrations or shorter with higher F-ara-A concentrations resulted in similar intracellular levels of F-ara-ATP as long as the products of fludarabine concentration and time of exposure were equal. These results and the fact that the fludarabine dose rate currently administered is well tolerated suggest that it may be the optimal dose rate for F-ara-ATP accumulation in CLL cells.     

Characteristics of the interatrial communication in patients undergoing transcatheter device closure of atrial septal defects for cryptogenic stroke

Background: Prior studies suggest that patent foramen ovale (PFO) diameter >4 mm is associated with a high probability of cryptogenic ischemic stroke (CIS). Methods: We evaluated all patients diagnosed with CIS who underwent closure of intra-atrial communication (IAC) using the Amplatzer atrial septal defect (ASD) occluder in our institution between August 1997 and March 2004. For each IAC, echocardiographic diameters and balloon-stretched diameters were recorded. Stretchability index was calculated as the ratio of stretched diameter to unstretched diameter. Results: Fifty-six patients met the inclusion criteria for this study. There was an inverse logarithmic relationship between unstretched IAC diameter and stretchability index. For the 28 smaller defects, the median IAC diameter was 2 mm, and median stretchability index was 5.58 (range 2.6–15). For the 28 larger defects, median diameter was 6 mm, and median stretchability index was 2.38 (range 1.05–5). The difference in stretchability index between the two groups was significant ( P < 0.0001). Conclusion: Our data bring into question the concept that the diameter of the defect would singularly predict the probability of stroke.     

Issues arising from the prenatal diagnosis of some rare trisomy mosaics--the importance of cryptic fetal mosaicism

OBJECTIVES: To add to the knowledge of fetal mosaicism, confined placental mosaicism (CPM), and uniparental disomy (UPD), in rare trisomies detected at prenatal diagnosis. METHODS: The origin of rare trisomy mosaics, mostly (8/11) seen in amniocytes, was examined in 11 cases by follow-up karyotyping and the study of microsatellite inheritance. RESULTS: Of the rare trisomies presented, three were mosaic trisomy 16 (two of which were CPM), and the remainder comprised single cases of mosaic trisomies of 8, 9, 10, 11, 12, 14, 5 and 15--the last two being CPM. Cases varied in parental derivation and meiotic versus post-zygotic origin but no case involved UPD. There was evidence for cryptic fetal mosaicism in three cases (5, 7, 11)--involving chromosomes 11, 14 and 16. CONCLUSIONS: These cases contribute further data to phenotypes associated with rare trisomies and the relative influences on the phenotype of CPM, UPD and fetal mosaicism. From sparse published data, we estimate that approximately 10% of apparent CPM cases for a rare trisomy (i.e. aneuploid CVS, normal amniocytes) may actually be cryptic fetal mosaics undetected in cultured amniocytes. In many cases, this cryptic mosaicism may be of limited clinical significance, but in others, the associated phenotypic effects may be obvious. There is no general approach to resolve this issue; the finding of even a few similar aneuploid cells in different amniocyte culture vessels may be clinically significant. It may be useful to study such an amniocyte culture with FISH with the relevant centromeric probe. Careful follow-up is recommended, particularly for infants where apparent correction of autosomal trisomy has occurred.     

SHOX mutations in a family and a fetus with Langer mesomelic dwarfism

Léri-Weill dyschondrosteosis (LWD) and Langer mesomelic dysplasia (LMD) are caused by mutations in the SHOX gene. LWD results from haploinsufficiency and is dominantly inherited, while the more severe LMD results from the homozygous loss of SHOX. We describe a family and fetus with two SHOX mutations. Several relatives carry an approximately 200 kb interstitial deletion that includes the whole SHOX gene. Their condition is mild, with no Madelung deformity, and was originally diagnosed as hypochondroplasia (HCH). This deletion was also transmitted to a female fetus. However, unlike her carrier relatives, the ultrasound scan of the fetus and subsequent autopsy were consistent with LMD. The fetus inherited an additional Xp deletion (Xpter-Xp22.12) that also included the SHOX gene from her chromosomally normal father. This represents a unique molecular condition for LMD: the fetus is a compound heterozygote with two independent deletions, one inherited and one arising from a de novo event.     

In vitro assessment of nucleoside analogs in multiple myeloma

Purpose To identify nucleoside analogs that may be effective for multiple myeloma (MM), we tested fludarabine, clofarabine, arabinosylguanine, cytarabine, troxacitabine, and gemcitabine in MM cell lines.Methods We employed biologic and biochemical assays in MM cell lines to evaluate the clinical potential of these nucleoside analogs.Results Among these purine and pyrimidine nucleoside analogs, fludarabine, clofarabine and gemcitabine were the most potent. MM cell lines, resistant to commonly used chemotherapeutic agents for this disease, were more sensitive to gemcitabine with an IC₅₀ in the nanomolar range. The greater cytotoxicity of gemcitabine in MM cells was consistent with greater accumulation of gemcitabine triphosphate, the major cytotoxic metabolite of this drug. MM.1S cells accumulated >100 M gemcitabine triphosphate but accumulated <20 M of the other analogs as the respective triphosphates. In addition incubation with gemcitabine resulted in inhibition of DNA synthesis. Incubation with 25, 50 or 100 nM gemcitabine resulted in a dose- and time-dependent increase in the cell population with a subG₁ DNA content indicative of apoptosis.Conclusions These results suggest that gemcitabine is a potent nucleoside analog in MM cell lines including cell types resistant to other chemotherapeutic agents. The greater activity of gemcitabine compared to other analogs seems to be due to favorable metabolism of this agent.This work was supported in part by grants CA57629 and CA85915 from the National Cancer Institute, Department of Health and Human Services and a Translational Research Award #6506-00 from the Leukemia and Lymphoma Society of America. Steven T. Rosen is the Dr. Ralph and Marion Falk Research Trust Translational Researcher of the Lymphoma Society of America.     

Identification and characterization of a novel efflux-related multidrug resistance phenotype in Staphylococcus aureus

Moxifloxacin is a C8-methoxy (C8-OMe) fluoroquinolone that is highly active against Staphylococcus aureus, including many strains resistant to older fluoroquinolones such as ciprofloxacin. Available data indicate that it is a poor substrate for the NorA multidrug efflux pump. We produced a mutant of S. aureus in vitro (SA-K2068) with a novel non-NorA-mediated multidrug resistance phenotype characterized by raised MICs of several fluoroquinolones, including the C8-OMe fluoroquinolones, moxifloxacin and gatifloxacin, and the organic cations ethidium and tetraphenylphosphonium. Reserpine reduced MIC increases by two- to eight-fold. SA-K2068 also demonstrated reduced accumulation of moxifloxacin, gatifloxacin and enoxacin, and increased efflux of ethidium, activities that were completely blocked by carbonyl cyanide m-chlorophenyl hydrazone (CCCP); competition experiments indicated that a single pump was responsible for the phenotype. The effect of CCCP and ionophores identified the proton motive force as the source of energy for efflux. These data, combined with previous work from our laboratory and genome sequence data, indicate that S. aureus possesses several multidrug efflux pump proteins and it is apparent that C8-OMe fluoroquinolones can be substrates for such pumps.