First trimester fetal karyotyping: one thousand diagnoses

Summary Cytogenetic investigations for diagnostic purposes were performed on 1000 first trimester samples of chorionic villi (CVS) in two laboratories using similar techniques. Fetal karyotyping was the primary indication for CVS in 912 and maternal age was the major indication in 758 of them. The risk category previous child/fetus with chromosome abnormality included 74 diagnoses, while the category chromosome abnormality in one of the parents included 38 diagnoses. Sex determination was the primary indication for CVS in 53 pregnancies. The overall incidence of chromosomal abnormalities was 70, of which 47 were balanced and 23 unbalanced. The results are detailed for each of the risk categories and the incidence of abnormal karyotypes is given for each year of maternal age. In the maternal age of 35–37 years the incidence of unbalanced karyotypes was 2.9% and in the years 38 onwards it was 6.6%. The incidence of unbalanced karyotypes was about 4% when the sampling was made in the weeks 9 to 12 but six abnormal karyotypes were found among 39 CVS performed at the eight week of gestation. The 11 trisomies of the type not found at birth were clustered between the 8th and the 10th week of pregnancy. The technical problems encountered in this experience and the preliminary estimates of fetal loss are discussed.     

Anterior approach to total hip replacement: surgical technique and clinical results of our first one thousand cases using non-cemented prostheses.

Total hip replacement has evolved into one of the most frequently performed reconstructive procedures in orthopaedic surgery today. A modified anterior approach developed by the senior surgeon has been utilized in performing over 3,000 operations in the past two decades. It is a unique and facile exposure. It can be easily applied to primary and revision surgery. Noncemented prostheses have been used in over 1,000 of these operations. This article details the surgical exposure, acetabular and femoral preparation for both non-cemented and cemented prostheses, special considerations for revision surgery, and the clinical results of the experience with noncemented prostheses to date.     

Mosaic structure of human coronavirus NL63, one thousand years of evolution

Before the SARS outbreak only two human coronaviruses (HCoV) were known: HCoV-OC43 and HCoV-229E. With the discovery of SARS-CoV in 2003, a third family member was identified. Soon thereafter, we described the fourth human coronavirus (HCoV-NL63), a virus that has spread worldwide and is associated with croup in children. We report here the complete genome sequence of two HCoV-NL63 clinical isolates, designated Amsterdam 57 and Amsterdam 496. The genomes are 27,538 and 27,550 nucleotides long, respectively, and share the same genome organization. We identified two variable regions, one within the 1a and one within the S gene, whereas the 1b and N genes were most conserved. Phylogenetic analysis revealed that HCoV-NL63 genomes have a mosaic structure with multiple recombination sites. Additionally, employing three different algorithms, we assessed the evolutionary rate for the S gene of group Ib coronaviruses to be approximately 3 x 10(-4) substitutions per site per year. Using this evolutionary rate we determined that HCoV-NL63 diverged in the 11th century from its closest relative HCoV-229E.     

Interactions between mitogenic stimuli, or, a thousand and one connections

Signals from G-protein-coupled receptors, tyrosine kinase receptors and integrins cooperate to determine cell growth. Work over the past two years has shown that this cooperation is based on crosstalk involving both receptors and their downstream signaling pathways. These interactions enable cells to integrate information from multiple stimuli that regulate cell cycle progression.     

Mycobacterium tuberculosis strains of the Beijing genotype are rarely observed in tuberculosis patients in South America

The frequency of the Beijing genotype of Mycobacterium tuberculosis as a cause of tuberculosis (TB) in South America was determined by analyzing genotypes of strains isolated from patients that had been diagnosed with the disease between 1997 and 2003 in seven countries of the subcontinent. In total, 19 of the 1,202 (1.6%) TB cases carried Beijing isolates, including 11 of the 185 patients from Peru (5.9%), five of the 512 patients from Argentina (1.0%), two of the 252 Brazilian cases (0.8%), one of the 166 patients from Paraguay (0.6%) and none of the samples obtained from Chile (35), Colombia (36) and Ecuador (16). Except for two patients that were East Asian immigrants, all cases with Beijing strains were native South Americans. No association was found between carrying a strain with the Beijing genotype and having drug or multi-drug resistant disease. Our data show that presently transmission of M. tuberculosis strains of the Beijing genotype is not frequent in Latin America. In addition, the lack of association of drug resistant TB and infection with M. tuberculosis of the Beijing genotype observed presently demands efforts to define better the contribution of the virulence and lack of response to treatment to the growing spread of Beijing strains observed in other parts of the world.     

Formation of a pathogen vacuole according to Legionella pneumophila: how to kill one bird with many stones

Legionella species are ubiquitous, waterborne bacteria that thrive in numerous ecological niches. Yet, in contrast to many other environmental bacteria, Legionella spp. are also able to grow intracellularly in predatory protozoa. This feature mainly accounts for the pathogenicity of Legionella pneumophila, which causes the majority of clinical cases of a severe pneumonia termed Legionnaires' disease. The pathomechanism underlying L. pneumophila infection is based on macrophage resistance, which in turn is largely defined by the opportunistic pathogen's resistance towards amoebae. L. pneumophila replicates in macrophages or amoebae in a unique membrane‐bound compartment, the Legionella‐containing vacuole (LCV). LCV formation requires the bacterial intracellular multiplication/defective for organelle trafficking (Icm/Dot) type IV secretion system and involves a plethora of translocated effector proteins, which subvert pivotal processes in the host cell. Of the ca. 300 different experimentally validated Icm/Dot substrates, about 50 have been studied and attributed a cellular function to date. The versatility and ingenuity of these effectors' mode of actions is striking. In this review, we summarize insight into the cellular functions and biochemical activities of well‐characterized L. pneumophila effector proteins and the host pathways they target. Recent studies not only substantially increased our knowledge about pathogen–host interactions, but also shed light on novel biological mechanisms.     

Directly observed therapy and improved tuberculosis treatment outcomes in Thailand

Background

The World Health Organization (WHO) recommends that tuberculosis (TB) patients receive directly observed therapy (DOT). Randomized controlled trials have not consistently shown that this practice improves TB treatment success rates. In Thailand, one of 22 WHO-designated high burden TB countries, patients may have TB treatment observed by a health care worker (HCW), family member, or no one. We studied whether DOT improved TB treatment outcomes in a prospective, observational cohort.

Methods and Findings

We prospectively collected epidemiologic data about TB patients treated at public and private facilities in four provinces in Thailand and the national infectious diseases hospital from 2004–2006. Public health staff recorded the type of observed therapy that patients received during the first two months of TB treatment. We limited our analysis to pulmonary TB patients never previously treated for TB and not known to have multidrug-resistant TB. We analyzed the proportion of patients still on treatment at the end of two months and with treatment success at the end of treatment according to DOT type. We used propensity score analysis to control for factors associated with DOT and treatment outcome. Of 8,031 patients eligible for analysis, 24% received HCW DOT, 59% family DOT, and 18% self-administered therapy (SAT). Smear-positive TB was diagnosed in 63%, and 21% were HIV-infected. Of patients either on treatment or that defaulted at two months, 1601/1636 (98%) patients that received HCW DOT remained on treatment at two months compared with 1096/1268 (86%) patients that received SAT (adjusted OR [aOR] 3.8; 95% confidence interval [CI] 2.4–6.0) and 3782/3987 (95%) patients that received family DOT (aOR 2.1; CI, 1.4–3.1). Of patients that had treatment success or that defaulted at the end of treatment, 1369/1477 (93%) patients that received HCW DOT completed treatment compared with 744/1074 (69%) patients that received SAT (aOR 3.3; CI, 2.4–4.5) and 3130/3529 (89%) patients that received family DOT (aOR 1.5; 1.2–1.9). The benefit of HCW DOT compared with SAT was similar, but smaller, when comparing patients with treatment success to those with death, default, or failure.

Conclusions

In Thailand, two months of DOT was associated with lower odds of default during treatment. The magnitude of benefit was greater for DOT provided by a HCW compared with a family member. Thailand should consider increasing its use of HCW DOT during TB treatment.     

The remarkable flexibility of the human antibody repertoire; isolation of over one thousand different antibodies to a single protein, BLyS

It is well established that the humoral immune response can generate antibodies to many different antigens. The antibody diversity required to achieve this is believed to be substantial. However, the extent to which the immune repertoire can generate structural diversity against a single target antigen has never been addressed. Here, we have used phage display to demonstrate the extraordinary capacity of the human antibody repertoire. Over 1000 antibodies, all different in amino acid sequence, were generated to a single protein, B-lymphocyte stimulator (BLyS™ protein). This is a highly diverse panel of antibodies as exemplified by the extensive heavy and light chain germline usage: 42/49 functional heavy chain germlines and 19/33 V_λ and 13/35 V_κ light chain germlines were all represented in the panel of antibodies. Moreover, a high level of sequence diversity was observed in the V_H CDR3 domains of these antibodies, with 568 different amino acid sequences identified. Thus we have demonstrated that specific recognition of a single antigen can be achieved from many different VDJ combinations, illustrating the remarkable problem-solving ability of the human immune repertoire. When studied in a biochemical assay, around 500 (40%) of these antibodies inhibited the binding of BLyS to its receptors on B-cell lines. The most potent antibodies inhibited BLyS binding with sub-nanomolar IC₅₀ values and with sub-nanomolar affinities. Such antibodies provide excellent choices as candidates for the treatment of BLyS-associated autoimmune diseases.