Molecular epidemiology of nalidixic acid-resistant campylobacter isolates from humans and poultry by pulsed-field gel electrophoresis and flagellin gene analysis

To investigate the potential of poultry products as the source of human infections associated with quinolone-resistant campylobacters, 140 human and 75 poultry isolates of nalidixic acid-resistant campylobacters were collected between 1996 and 1998, and analysed by two molecular typing methods. By the analysis of restriction fragment length polymorphism of the flagellin gene, 33 distinct patterns were obtained, with 18 of which shared by both human (89%) and poultry (93%) isolates. By the pulsed-field gel electrophoresis of SmaI-restricted macrofragments, 105 different profiles were obtained, and 11 were found in both human (40%) and poultry (23%) isolates. When the two typing methods were combined, 112 unique genotypes were obtained, 11 of which were shared by both populations, including 53 (38%) human isolates and 14 (19%) poultry isolates. Although domestic poultry products are still important sources of the quinolone-resistant campylobacter infections in humans, there are other factors that might contribute to these increasing infections simultaneously. A more stringent policy in the use of antimicrobial agents in food animals can no longer be ignored.

Deep neck infections in children

From December 1989 through 1998, a total of 68 children with deep neck infection were enrolled into this study. The mean age was 5.9 years (range, 1 month-15.8 years). Infections in the retropharyngeal space (36.7%) were most common, followed by parapharyngeal space (30.8%), peritonsillar space (20.6%), and submandibular space (11.9%). Fever, neck pain, and swelling were the most frequent symptoms. The most common pathogens were viridans streptococci (41%, 16/39) and Staphylococcus aureus (26%, 10/39). Other isolates included Prevotella spp., Veillonella spp., Klebsiella pneumoniae, Escherichia coli, Morganella spp., and Enterobacter spp. Mixed infection was found in 46% (18/39) of patients. The mean duration of hospitalization was 12.4 days (range, 2-45 days). Complete resolution was achieved in 61 (89.7%) children. Complications occurred in 7 patients, including recurrence, mediastinal spread, bacteremia, and suppurative thyroiditis; the patient with mediastinal spread plus bacteremia died. Five patients had congenital cyst and 4 of them had complications or recurrence/relapse. In conclusion, infections in the retropharyngeal space and polymicrobial infections were most common in deep neck infection of Taiwan children.

The tetrapod limb: a hypothesis on its origin

A wrist joint and structures typical of the hand, such as digits, however, are absent in [Eustenopteron] (Andrews and Westoll, '68, p 240). Great changes must have been undergone during evolution of the ankle joint; the small number of large bones in the fin must somehow have developed into a large number of small bones, and it is very difficult to draw homologies in this region, or even be certain of what is being compared (Andrews and Westoll, '68, p 268). The tetrapod limb is one of the major morphological adaptations that facilitated the transition from an aquatic to a terrestrial lifestyle in vertebrate evolution. We review the paleontological evidence for the fin-limb transition and conclude that the innovation associated with evolution of the tetrapod limb is the zeugopodial-mesopodial transition, i.e., the evolution of the developmental mechanism that differentiates the distal parts of the limb (the autopodium, i.e., hand or foot) from the proximal parts. Based on a review of tetrapod limb and fish fin development, we propose a genetic hypothesis for the origin of the autopodium. In tetrapods the genes Hoxa-11 and Hoxa-13 have locally exclusive expression domains along the proximal-distal axis of the limb bud. The junction between the distal limit of Hoxa-11 expression and of the proximal limit of Hoxa-13 expression is involved in establishing the border between the zeugopodial and autopodial anlagen. In zebrafish, the expression domains of these genes are overlapping and there is no evidence for an autopodial equivalent in the fin skeleton. We propose that the evolution of the derived expression patterns of Hoxa-11 and Hoxa-13 may be causally involved in the origin of the tetrapod limb.

Secular trends in incidence and antimicrobial resistance among clinical isolates of Salmonella at a university hospital in Taiwan, 1983-1999

The incidence and antimicrobial resistance among clinical isolates of salmonella at a university hospital in Taiwan between 1983 and 1999 are summarized in this report. A total of 7986 isolates were analysed. Serogroup B has been the most prevalent over the years, with an apparently continuous decline after 1995. Concordant decrease was also found among S. choleraesuis and S. typhi isolates in recent years. In contrast, the proportion of serogroup D strains increased significantly after 1996. S. typhi remained relatively susceptible to most of the antimicrobial agents examined. For non-typhoidal isolates, antimicrobial resistance to ampicillin (62%), chloramphenicol (67%), and sulfamethoxazole-trimethoprim (37%) was relatively higher than that reported elsewhere. Newer generation cephalosporins and fluoroquinolones remained effective over the years, although emerging resistance to these drugs has been noticed since 1992. A more prudent selection and use of antimicrobial agents, in both humans and animals, and a continuous surveillance of resistance are essential in the future.

Role of calcium-independent phospholipases (iPLA(2)) in phosphatidylcholine metabolism

The proposed role of calcium-independent phospholipase A(2) (iPLA(2)) in membrane phospholipid homeostasis was tested by examining the perturbation of phosphatidylcholine metabolism by enzyme overexpression. There are alternatively spliced forms of murine iPLA(2) that were widely expressed in mouse tissues: a long form containing exon-9 that is membrane-associated and a short form lacking exon-9 that is distributed between the membrane and cytosolic fractions. Enforced expression of either iPLA(2) isoform led to a significant increase in intracellular free fatty acid, lysophosphatidylcholine, and GPC without a concomitant increase in the incorporation of either exogenous arachidonic acid or choline. The accumulation of lysophosphatidylcholine in iPLA(2)-expressing cells illustrates the limited capacity of cells for reacylation and degradation of lysophospholipids. Since iPLA(2) overexpression did not accelerate either phospholipid remodeling or phosphatidylcholine synthesis, this enzyme does play a determinant (rate-controlling?) role in either of these cellular processes.

Characteristics of group A streptococcal bacteremia with comparison between children and adults

This retrospective study aimed to compare the characteristics of group A streptococcal bacteremia in children and adults. A total of 76 (12 children and 64 adults) patients with group A streptococcal bacteremia treated from October 1995 through September 2000 at the Linko Chang Gung Memorial Hospital were included. The mean age was 47.6 years (range, 12 days-90 years). Forty-four (57.9%) patients had predisposing medical conditions. Malignant cancer (23.7%) and diabetes (22.4%) were the 2 most common conditions, which occurred only in adults. Two (16.7%) children had chickenpox associated with secondary group A streptococcal bacteremia. Skin and soft tissue infection (60.5%) was the most common clinical manifestation. The mortality rate related to group A streptococcal bacteremia was 25%. Twelve patients met the criteria of streptococcal toxic shock syndrome and 6 (50%) were children (p<0.05). Despite immediate and aggressive treatment, mortality due to streptococcal toxic shock syndrome was 66.7%. The incidence of streptococcal toxic shock syndrome was much higher in children (50%) than in adults (9.4%). Early diagnosis of invasive group A streptococcal infections and streptococcal toxic shock syndrome requires awareness of the presentations and a high level of suspicion. For fulminant group A streptococcal infection, a combination of a beta-lactam antibiotic plus clindamycin and/or adjuvant therapy with intravenous immunoglobulin is recommended.

Liver abscess caused by Klebsiella pneumoniae in siblings

Klebsiella pneumoniae has been emerging as the leading cause of liver abscess in diabetic patients. Results of molecular typing of K. pneumoniae isolates from two siblings with liver abscess, their family members, and the environment suggest a possibility of cross infection of liver abscess by the fecal-oral route within diabetic patients.

Large drug resistance virulence plasmids of clinical isolates of Salmonella enterica serovar Choleraesuis

Salmonella enterica serovar Choleraesuis generally causes systemic human salmonellosis without diarrhea, and therefore, antimicrobial treatment is essential for such patients. The drug resistance information on this organism is thus of high value. Serovar Choleraesuis usually harbors a virulence plasmid (pSCV) of 50 kb in size. Of the 16 clinical isolates identified to be serovar Choleraesuis, all except one harbored a pSCV and seven of them carried a pSCV of more than 125 kb in size. A pSCV was defined as a plasmid carrying spvC and characteristic deletions detected by PCR and by DNA-DNA hybridization (for the former criterion). The results of PCR, restriction fragment profiles, and Southern DNA-DNA hybridizations of the profiles all indicated that such larger pSCVs were derived from the 50-kb plasmid recombined with non-pSCVs found in some clinical isolates. Fifteen of the 17 strains, including a laboratory strain, were then tested for drug resistance against 16 antibiotics with E-test and the dilution method. The laboratory strain, which harbored a 50-kb pSCV and a 6-kb non-pSCV, was resistant only to sulfonamides (SUL), and its resistance gene, sulII, checked with PCR and DNA-DNA hybridization, was located on the 6-kb non-pSCV. All 14 clinical strains were resistant to multiple drugs. Of the 14, 7 were resistant to SUL, and the resistance gene was located on a plasmid. The sulII gene, but not bla(TEM-1), was carried only on the 6-kb non-pSCV. Of the remaining six large plasmids, three of 90 kb, two of 136 kb, and one of 140 kb, the last three were pSCVs and carried the other SUL gene (sulI) and the bla(TEM-1) gene. The six strains were also resistant to trimethoprim-sulfamethoxazole. None of the 50-kb pSCVs carried resistance genes. These drug resistance genes on the large pSCVs were apparently also acquired through recombination.

Childhood and adolescent tuberculosis in northern Taiwan: an institutional experience during 1994-1999

This study evaluated the clinical characteristics of childhood and adolescent tuberculosis (TB) at the end of the twentieth century in a referral children's hospital in northern Taiwan. The hospital charts were reviewed retrospectively of children/adolescents aged less than 18 y who were seen in a children's hospital in northern Taiwan between 1994 and 1999 and diagnosed with TB. A total of 62 individuals was diagnosed during this period. The patients' demographic data, presenting symptoms, clinical features, bacteriological results, drug susceptibility and tuberculin skin-test results were analysed. Most diagnosed cases lay in one of two main age ranges, younger than 5 y and adolescents. The presenting symptoms of study subjects were typically non-specific. Bone involvement occurred for 21 patients (33.9%) and was the most common extrapulmonary manifestation. Mycobacterium tuberculosis was isolated from 47 patients (75.8%). Five isolates were resistant to pyrazinamide, three to streptomycin and one to isoniazid, but no multidrug resistant isolates of TB were detected from culture-proven cases. Seventeen of 47 (36.2%) culture-proven patients revealed negative acid-fast staining initially but, subsequently, M. tuberculosis was isolated from various clinical specimens using a standard method at a later date. The tuberculin skin test was positive for 24 of 32 patients (75%) who received such an examination.

CONCLUSION

Extrathoracic TB was more common in children below 5 y of age than their adolescent counterparts, and chiefly involved the peripheral long bones. The potential drug resistance of M. tuberculosis in childhood and adolescent TB did not appear to have been a major problem in northern Taiwan before the year 2000.

Endogenous endophthalmitis and necrotising pneumonia caused by Klebsiella pneumoniae in a child with beta-thalassaemia major

A case beta-thalassaemia major complicated with Klebsiella pneumoniae endogenous endophthalmitis is presented to increase physician awareness of the association of the two clinical conditions. Severe morbidity including subretinal abscess and retinal detachment may develop despite aggressive intravenous and intravitreal ceftriaxone therapy, along with vitrectomy and external drainage.

Effect of N(G)-nitro-L-arginine methyl ester on intestinal permeability following intestinal ischemia-reperfusion injury in a rat model

Subclinical intestinal ischemia-reperfusion injury (IRI) causes an increase in mucosal permeability and may represent an early event in the pathogenesis of necrotizing enterocolitis in premature infants. Previous studies suggested that continuous, endogenous formation of nitric oxide (NO) maintains the mucosal integrity of the intestine, thus protecting the gut from injuries from blood-borne toxins and tissue-destructive mediators. This study was undertaken to assess whether the inhibition of NO production causes an increase in intestinal permeability in rats following IRI. Sprague-Dawley rats weighing 200-300 g were divided into 4 groups: (1) untreated group (normal control); (2) ischemia-reperfusion group; (3) early N(G)-nitro-L-arginine methyl ester (L-NAME), a specific inhibitor of NO production, treatment group, and (4) late L-NAME treatment group. Transient IRI was induced by 30-min occlusion, followed by reperfusion of the isolated ileal loop. The L-NAME was administered 15 min before and after mesenteric ischemia as a 25-mg/kg bolus. Fluorescein isothiocyanate-dextran (FITC-D) was used to quantitatively assess the alteration in mucosal permeability of the intestine. There was no significant increase in the portal vein FITC-D level among normal controls, ischemia-reperfusion group and late L-NAME-treated group, but there was an approximately 6-fold increase in the early L-NAME treatment group. The pathological features of the intestine following IRI include denudation of the villus epithelium and reduction of villus height, associated with marked inflammatory cell infiltration over the lamina propria. These results suggest that endogenous NO may play a role in the protecting intestinal integrity after IRI.

Epstein-Barr virus-associated hemophagocytic syndrome masquerading as lymphoma: a case report

Virus-associated hemophagocytic syndrome (VAHS) is a non-neoplastic, generalized histiocytic proliferation with prominent hemophagocytosis associated with a systemic viral infection. Although Epstein-Barr virus (EBV) is one candidate virus for this association, thorough serologic and molecular biologic studies to determine the presence of the viral infection have been lacking in many reports. Whereas elevated liver function tests are common findings in patients with VAHS, exudative ascites and abdominal lymphadenopathy are rare. We describe a case of EBV-AHS masquerading as lymphoma in which treatment with intravenous immunoglobulins was associated with complete clinical remission at 2 years and 6 months after the onset. Regardless of the exact mechanism responsible for ascites formation in VAHS, this case adds support to the possible involvement of EBV in patients with abdominal lymphadenopathy and ascites.

Surgical implications of pseudomonas aeruginosa necrotizing fasciitis in a child with acute lymphoblastic leukemia

Necrotizing fasciitis caused by Pseudomonas aeruginosa is extremely rare. Only 4 cases were reported in the literature. The authors report the occurrence of P aeruginosa necrotizing fasciitis starting out as a vulval abscess in a girl before induction chemotherapy for acute lymphoblastic leukemia. To our knowledge, this is the second case described in association with leukemia. In this case, the outcome was favorable because of early surgical intervention, confirming the diagnosis. J Pediatr Surg 36:948-950.

Ginseng flowers stimulate progesterone production from bovine luteal cells

Our previous report first showed evidence that polysaccharides isolated from ginseng leaves obtained from Jilin, China possess luteotropic activities. In this study, we made further investigations on the root and flowers of Korean ginseng by means of the same bioassay system described briefly as follows. Frozen-thawed bovine luteal cells (1 x 10(5) cells/ml/well) in M199 were incubated in 24-well culture plates at 37 degrees C in a 5 % CO2 incubator. Ten microl of tested drugs with 1, 10 and 100 microg/ml were added into each well. After 4- and 24-hr incubation, the media were harvested and assayed for progesterone by an enzyme immunoassay. The production of progesterone from cells is the indicator for evaluating the action of tested drugs. Results showed that hot water extracts ofginseng flowers (GF-1) with 10 to 100 microg/ml significantly increased progesterone production, whereas those from ginseng root (GR-1) could not. Crude polysaccharides (GF-2) isolated from GF-1 is the active component and the small molecules (mw < 10,000 dalton) are excluded, indicating that the ginseng root has no luteotropic activities, but the polysaccharides of ginseng flowers have.

Carriage of antibiotic-resistant pneumococci among Asian children: a multinational surveillance by the Asian Network for Surveillance of Resistant Pathogens (ANSORP)

To investigate the nasal carriage of antibiotic-resistant pneumococci by children, anterior nasal swabs were done for 4963 children <5 years old in 11 countries in Asia and the Middle East. In total, 1105 pneumococci isolates (carriage rate, 22.3%) were collected, 35.8% of which were found to be nonsusceptible to penicillin. Prevalence of penicillin nonsusceptibility was highest in Taiwan (91.3%), followed by Korea (85.8%), Sri Lanka (76.5%), and Vietnam (70.4%). Penicillin resistance was related to residence in urban areas, enrollment in day care, and a history of otitis media. The most common serogroups were 6 (21.5%), 23 (16.5%), and 19 (15.7%). The most common clone, as assessed by pulsed-field gel electrophoresis, was identical to the Spanish 23F clone and to strains of invasive isolates from adult patients. Data in this study documented the high rate of penicillin or multidrug resistance among isolates of pneumococci carried nasally in children in Asia and the Middle East and showed that this is due to the spread of a few predominant clones in the region.

Acute disseminated encephalomyelitis in autoimmune hemolytic anemia

A 16-year-old female with chronic autoimmune hemolytic anemia is presented. She was diagnosed with acute disseminated encephalomyelitis by clinical findings and magnetic resonance imaging (MRI), and the condition occurred after a systemic infection with Cryptococcus neoformans. Intravenous immunoglobulin therapy remarkably improved the patient's neurologic deficit and resolved abnormalities evidenced on MRI. To our knowledge, this report is the first of a pediatric patient with autoimmune hemolytic anemia complicated by acute disseminated encephalomyelitis that developed after an apparently successful treatment of cryptococcal meningitis.

Lack of evidence of an association between the carriage of virulence plasmid and the bacteremia of Salmonella typhimurium in humans

The involvement of the virulence plasmid (pSTV) of Salmonella typhimurium in human salmonellosis was examined. Most of the 224 clinical strains isolated from the blood (53) and nonblood samples (171) contained a 90 kb or larger plasmid, most of which were pSTV. The rates of pSTV carriage in the isolates showed no statistically significant difference between those derived from the blood and those from other sources (87% vs. 83%; chi2=0.49, 0.1<P<0.9), suggesting that pSTV may not play a critical role in promoting S. typhimurium bacteremia in humans. Nine strains with representative plasmid profiles were tested for the mouse virulence. The result revealed that these clinical isolates contained all three virulent types known: the avirulent, the highly virulent when a pSTV was present, and the moderately virulent regardless of the presence or absence of pSTV. This indicated that mouse virulence of S. typhimurium did not correlate their virulence in humans. Clinical data showed that most patients with primary bacteremia had underlying immunosuppressive diseases, whereas only a few patients with secondary bacteremia had preexisting diseases (87% vs. 13%; chi2=22.73, P<0.005). It is suggested that the contribution of pSTV to S. typhimurium bacteremia in humans is likely to be limited, and both the host factor and the microbial virulence determinants on the chromosome are more important than virulence plasmid in predisposing patients to bacteremia.

Septic arthritis of the hip caused by Salmonella typhi

We describe septic arthritis of the hip in a child with typhoid fever. The aetiological diagnosis was confirmed by a positive Widal test as well as by isolation of Salmonella typhi from joint aspirate. Treatment with ceftriaxone along with surgical drainage was successful.

MDM2 and MDMX can interact differently with ARF and members of the p53 family

Members of the p53 family of transcription factors have essential roles in tumor suppression and in development. MDM2 is an essential regulator of p53 that can inhibit the transcriptional activity of p53, shuttle p53 out of the nucleus, and target p53 for ubiquitination-mediated degradation. Little is known about the interaction and selectivity of different members of the p53 family (p53, p63, and p73) and the MDM2 family (MDM2 and MDMX). Here we show that the transcriptional activities of p53 and p73, but not that of p63, were inhibited by both MDM2 and MDMX. Consistent with these, we found that MDMX can physically interact with p53 and p73, but not with p63. Moreover, ectopically expressed MDM2 and MDMX could induce alterations in the subcellular localization of p73, but did not affect the subcellular localization of p53 and p63. Finally, we demonstrate that while ARF can interact with MDM2 and inhibit the regulation of p53 by MDM2, no interaction was found between ARF and MDMX. These data reveal that significant differences and selectivity exist between the regulation of different members of the p53 family by MDM2 and MDMX.

Determination of polychlorinated dibenzo-p-dioxin and dibenzofuran congeners in air particulate and marine sediment standard reference materials (SRMs)

Due to the limited number of environmental matrix certified reference materials (CRMs) with assigned values for natural levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), an interlaboratory study was undertaken by the National Institute of Standards and Technology (NIST) and Environment Canada to establish reference concentration values for selected PCDD/Fs in two well-characterized NIST Standard Reference Materials (SRMs): SRM 1649a (Urban Dust) and SRM 1944 (New York/New Jersey Waterway Sediment). Results from 14 laboratories were used to provide reference values for the seventeen 2, 3, 7, 8-substituted PCDD/F congeners, the totals for individual tetra- through hepta-substituted PCDD/F homologues, and the total amount of tetra- through hepta-substituted PCDD/Fs. The mass fractions for the individual 2, 3, 7, 8-substituted congeners range from approximately 0.01 microg/kg to 7 microg/kg dry mass.

Gene conversion may aid adaptive peak shifts

Gene conversion is often viewed as a homogenizing force that opposes adaptive evolution. The objective of this study is to suggest a potential role for gene conversion in adaptive evolution of proteins through aiding the transfer of a population from one adaptive peak to another. Our hypothesis starts with the observation that a tandem gene duplication may result in an extra gene copy that is released from selective constraints. In such cases, individually deleterious mutations may accumulate on the extra copy of the gene, and through gene conversion these mutations may subsequently be presented to the functioning gene for selection en masse. Thus, groups of mutations that jointly confer a selective advantage may regularly be made available for selection. We present a mathematical model of this process and identify the range of rates of gene conversion, gene duplication and mutation under which it may operate. The results indicate that the process may be biologically feasible if the rate of appearance of the potentially beneficial mutations is not too small in relation to the rates of null mutation and of gene conversion. This process appears to be a possible mechanism for effecting adaptive peak shifts in large populations. We show that all the evolutionary steps in the proposed model may have occurred in the evolution of primate gamma -globin genes. We suggest that hide-and-release mechanisms for genetic variation may constitute a more general principal of evolvability.

Humans and old world monkeys have similar patterns of fetal globin expression

The expression of epsilon- and gamma-globin mRNA and protein has been determined in three Old World monkey species (Macaca mulatta, Macaca nemestrina, and Cercopithecus aethiops). Using RT-PCR with primers for epsilon- and gamma-globin, both mRNAs were detected in early fetal stages, whereas at 128 days (85% of full term), only gamma was expressed. High-performance liquid chromatography was used for separation and quantitation, and matrix-assisted laser desorption/ionization mass spectrometry was used for identification of globin polypeptides. An alpha-globin polymorphism was observed in all of the species examined. During fetal life, gamma-globin was the predominant expressed beta-type globin. The red blood cells of infants still contained substantial amounts of gamma-globin, which declined to negligible levels in 14 weeks as beta-globin expression reached adult values. The ratio of gamma1- to gamma2-globins (equivalent to Ggamma/Agamma in humans) was approximately 2.5, similar to the Ggamma/Agamma ratio observed in humans. Thus, gamma-globin gene expression in these Old World monkeys species has three features in common with human expression: expression of both duplicated gamma genes, the relative preponderance of gamma1 over gamma2 expression, and the delay of the switch from gamma- to beta-globin until the perinatal period. Thus, the catarrhines seem to share a common pattern of developmental switching in the beta-globin gene cluster, which is distinct from the timing of expression in either prosimians or the New World monkeys. Our results indicate that an Old World monkey, such as Rhesus, could serve as a model organism (resembling humans) for experimentally investigating globin gene expression patterns during the embryonic, fetal, and postnatal stages.