Same-day or next-day sentinel node biopsy after lymphoscintigraphy for melanoma using 99m Tc-labelled antimony sulphide colloid.

BACKGROUND: Two recent publications have reported that a shorter interval between preoperative lymphoscintigraphy and sentinel node biopsy (SNB) is associated with improved survival of patients with primary cutaneous melanoma. The aims of this study were to analyse prospectively collected survival data for patients who had SNB on the same day as lymphoscintigraphy or the day after; and to assess tracer migration from sentinel nodes to second-tier nodes after lymphoscintigraphy on the previous day. METHODS: Outcome data were obtained for patients who had lymphoscintigraphy and SNB on the same day (time interval less than 8 h) or the next day (interval more than 16 h). In a separate prospective cohort, same-day and next-day lymphoscintigraphic images of sentinel nodes and second-tier nodes were compared. RESULTS: Following lymphoscintigraphy, 2848 patients had same-day and 3328 had next-day SNB. Survival outcomes did not differ between these groups. In a prospectively studied cohort of 30 patients, none had significant tracer migration from sentinel nodes to second-tier nodes on imaging the following day. CONCLUSION: No difference in survival after same- or next-day sentinel node biopsy is seen when 99m Tc-labelled antimony sulphide colloid is used. This may be because of less tracer migration to second-tier nodes.

ANTECEDENTES: Dos publicaciones recientes han señalado que reducir el intervalo entre la linfografía isotópica preoperatoria y la biopsia del ganglio centinela (sentinel node biopsy, SNB) se asocia con una mejor supervivencia en pacientes con melanoma maligno primario. Los objetivos de este estudio fueron los siguientes: (1) analizar los datos de supervivencia recogidos prospectivamente en pacientes en los que se realiza la SNB el mismo día o al día siguiente de la linfografía isotópica, y (2) evaluar la migración del marcador desde los ganglios centinela a los ganglios de segundo nivel a partir de la linfografía del día anterior. MÉTODOS: Se analizaron los resultados de los pacientes a los que se realizó una linfografía isotópica y la SNB el mismo día (intervalo de tiempo < 8 h) o al día siguiente (intervalo > 16 h). En una cohorte prospectiva diferente, se compararon las imágenes de los ganglios centinela y de los ganglios de segundo nivel en linfografías isotópicas realizadas el mismo día o al día siguiente. RESULTADOS: Tras la linfografía isotópica, se realizó la SNB el mismo día en 2.848 pacientes y al día siguiente en 3.328 pacientes. No hubo diferencias en la supervivencia entre ambos grupos. En una cohorte de 30 pacientes estudiada de forma prospectiva, no hubo migración significativa del trazador de los ganglios centinela a los ganglios de segundo nivel en las imágenes obtenidas al día siguiente. CONCLUSIÓN: La mejor supervivencia que se obtiene cuando se realiza la SNB poco después de la linfografía isotópica podría explicarse por una diferencia en la migración del trazador a los ganglios de segundo nivel entre los dos marcadores utilizados: nanocoloide de albúmina humana o coloide de sulfuro de antimonio, ambos marcados con 99mTc. En este estudio y con este último marcador, no se observó migración a ganglios de segundo nivel durante la noche.

40Ca(alpha, gamma)44Ti reaction in the energy regime of supernova nucleosynthesis.

The 44Ti(t1/2=59 yr) nuclide, an important signature of supernova nucleosynthesis, has recently been observed as live radioactivity by gamma-ray astronomy from the Cas A remnant. We investigate in the laboratory the major 44Ti production reaction 40Ca(alpha, gamma)44Ti (Ec.m. approximately 0.6-1.2 MeV/u by direct off-line counting of 44Ti nuclei. The yield, significantly higher than inferred from previous experiments, is analyzed in terms of a statistical model using microscopic nuclear inputs. The associated stellar rate has important astrophysical consequences, increasing the calculated supernova 44Ti yield by a factor approximately 2 over previous estimates and bringing it closer to Cas A observations.

Stellar (n,gamma) cross section of 62Ni.

The 62Ni(n,gamma)63Ni(t(1/2)=100+/-2 yr) reaction plays an important role in the control of the flow path of the slow neutron-capture (s) nucleosynthesis process. We have measured for the first time the total cross section of this reaction for a quasi-Maxwellian (kT=25 keV) neutron flux. The measurement was performed by fast-neutron activation, combined with accelerator mass spectrometry to detect directly the 63Ni product nuclei. The experimental value of 28.4+/-2.8 mb, fairly consistent with a recent calculation, affects the calculated net yield of 62Ni itself and the whole distribution of nuclei with 62

Determination of the 8B neutrino spectrum.

We have measured the total energy of the alpha particles following the beta decay of 8B by implanting 8B into a planar silicon surface barrier detector. Calibration was performed using alpha particles following the beta decay of 20Na, similarly implanted. The alpha spectrum is used to infer the 8B neutrino spectrum which is an important input in the interpretation of experiments that detect energetic neutrinos from the Sun. The alpha spectrum reported here is in disagreement with the previous best measurement which used two detectors in coincidence.

Large angle elastic alpha scattering on a N=Z nucleus above A=40.

Scattering of alpha particles from 44Ti, the lightest unstable alpha-particle nucleus above A=40, has been measured at backward angles. The "anomalous" order-of-magnitude enhancement that is characteristic of 40Ca and other light alpha-particle nuclei is not observed. Instead, the backward yield is similar to that observed for other nuclei heavier than 40Ca, and is well described with average optical model parameters.

Unexpected behavior of heavy-ion fusion cross sections at extreme sub-barrier energies.

The excitation function for fusion evaporation in the (60)Ni+ (89)Y system was measured over a range in cross section covering 6 orders of magnitude. The cross section exhibits an abrupt decrease at extreme sub-barrier energies. This behavior, which is also present in a few other systems found in the literature, cannot be reproduced with present models, including those based on a coupled-channels approach. Possible causes are discussed, including a dependence on the intrinsic structure of the participants.

Long-term survival of Escherichia coli O157 on pasture following an outbreak associated with sheep at a scout camp.

AIMS: To monitor the decay of E. coli O157 in soil (loamy sand) on a scout campsite following an outbreak in humans. METHODS AND RESULTS: Samples of soil and sheep faeces were collected from the campsite and tested for the presence of E. coli O157 by immunomagnetic separation (IMS) after enrichment in buffered peptone water + vancomycin at 42 degrees C for 6 h. Enumeration of target was carried out by direct plating onto sorbitol MacConkey agar plates supplemented with cefixime and tellurite (CTSMAC) incubated at 37 degrees C for 24 h. Low numbers (< 100 g(-1)) were estimated by the most probable number (3-tube MPN) technique. CONCLUSIONS: Survival was observed for 15 weeks. SIGNIFICANCE AND IMPACT OF THE STUDY: A number of laboratory studies have followed the decay of E. coli O157 in soil, animal faeces and water. This study follows (for the first time) the decay of the organism in soil after an outbreak associated with sheep. It demonstrates the long-term persistence of the organism in the environment and the results will be potentially important in performing risk assessments for both human and animal infection.

Rapid diversification of a species-rich genus of neotropical rain forest trees.

Species richness in the tropics has been attributed to the gradual accumulation of species over a long geological period in stable equatorial climates or, conversely, to speciation in response to late Tertiary geological events and unstable Pleistocene climates. DNA sequence data are consistent with recent diversification in Inga, a species-rich neotropical tree genus. We estimate that speciation was concentrated in the past 10 million years, with many species arising as recently as 2 million years ago. This coincides with the more recent major uplifts of the Andes, the bridging of the Isthmus of Panama, and Quaternary glacial cycles. Inga may be representative of other species-rich neotropical genera with rapid growth and reproduction, which contribute substantially to species numbers in the world's most diverse flora.

Intergenic spacer (IGS) polymorphism: a new genetic marker for differentiation of Toxoplasma gondii strains and Neospora caninum.

The region between the 28S and 18S rRNA genes, including the intergenic spacer (IGS) region and the 5S rRNA gene, from 32 strains of Toxoplasma gondii and the NC1 strain of Neospora caninum was amplified and used for DNA sequencing and/or restriction fragment length polymorphism (RFLP) analysis. The 5S rDNA sequences from 20 strains of T. gondii were identical. The IGS region between the 5S and 18S rRNA genes (nontranscribed spacer 2 or NTS 2) showed 10 nucleotide variations. Six of the 10 variant positions correlated with the murine virulence of the strains. Intraspecific polymorphisms distinguished the virulent strains of zymodemes 5, 6, and 8 from other virulent strains (in zymodeme 1). RFLP methods (IGS-RFLP) were developed and used to characterize the virulent and avirulent patterns among 29 T. gondii strains. Sequence diversity of 19.8% was found between T. gondii and N. caninum when comparing a region of 919 bp at the 3' end of NTS 2. The sequence variation in ribosomal IGS could therefore be a useful marker for Toxoplasma strain identification and for distinguishing N. caninum from T. gondii.

VTEC: lessons learned from British outbreaks.

Important Escherichia coli O157 outbreaks in England and Scotland since 1982-83 are reviewed. The scientific lessons learned from them are described and their legal consequences outlined. The light shed by them on relationships between law and science is discussed, and questions of blame are analysed in the context of Reason's 'resident pathogen' metaphor and Vaughan's study of the 1986 Challenger Space Shuttle disaster.

Molecular typing of Toxoplasma gondii strains by GRA6 gene sequence analysis.

The utility of sequence polymorphisms in the dense granule antigen GRA6 gene as typing markers for Toxoplasma gondii was investigated. The coding region of GRA6 was amplified, sequenced and compared for 30 Toxoplasma strains from eight different zymodemes (Z1-Z8). Sequence alignment identified nucleotide polymorphisms at 24 positions out of 690 bp, which correlated with murine-virulence. Types I, II, and III could be distinguished from each other on the basis of three, 10, and six variable positions, respectively. Two deletions of 15 bp and 3 bp existed in the avirulent (type II) strains. With one exception, all polymorphic positions resulted in amino acid substitutions, and the two gaps of 15 bp and 3 bp caused the deletion of six amino acids in type II strains. Intra-specific polymorphisms were also found in the virulent group. A high degree of sequence polymorphism correlating with the phenotypes of T. gondii strains points to the GRA6 gene being a good marker for strain characterisation and typing of the isolates of this apicomplexan. The large variety of amino acid changes supports the view that the GRA6 protein plays an important role in the antigenicity and pathogenicity of T. gondii. The existence of polymorphic restriction sites for endonuclease MseI was used to develop a PCR-RFLP method which could simply differentiate the three different groups (types I, II, III) of T. gondii.

Manufacturing of a fiber optic Young's double pinhole interferometer for use as a 3-D profilometer.

The method used to manufacture a Young's double pinhole interferometer is dis ussed. This interferometer is destined to be used in a surface profilometer using two wavelengths so that the zero order fringe can be determined. Hence stringent requirements are placed on the absolute length difference between the two output fibers of a single mode coupler. These requirements are discussed along with the manufacturing process. The interferometer is shown along with measurements showing a length difference on the order of 6microm.

Molecular typing methods for Neisseria meningitidis.

Neisseria meningitidis is an important pathogen because it causes life-threatening infections. The rapid course of meningococcal disease and the capacity of some serogroups to cause large-scale epidemics necessitates the use of sensitive, reliable and rapid typing methods to characterise strains. Molecular typing techniques for N. meningitidis are used for epidemiological purposes to investigate outbreaks and the spread of organisms and to examine the population genetic structure of the organism to understand better its variation and evolution. Many investigators have employed molecular typing methods and shown that meningococcal disease is associated with a variety of different epidemiological patterns. The choice of a typing method is dependent upon the epidemiological questions to be answered and on the population genetics of the organism under investigation. With highly clonal populations comprising independent non-recombining lineages such as serogroup A meningococci, ribotyping, multilocus enzyme electrophoresis (MLEE), pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), PCR with arbitrary primers (RAPD) or with other gene-based primers each provides a constant measure of the relationship between strains. A more restricted portfolio of molecular methods - PFGE, MLEE and MLST - is appropriate for the investigation of less clonal serogroup B and C meningococci from localised outbreaks. If a thorough evaluation of the overall population is sought to determine the relationship between new isolates and members of hyper-endemic clonal complexes then quantitative methods such as MLEE and MLST are necessary. Several PCR-based methods are used for the detection and typing of meningococcal strains, many requiring rigorous standardisation before they can be considered suitable for rapid and reliable differentiation between clones. This review examines strain characterisation by molecular techniques and non-culture-based subtyping of meningococci in clinical specimens. It assesses the importance of these techniques and examines the epidemiological questions that they answer and also their limitations.

In vitro activities of meropenem and other antimicrobial agents against British meningococcal isolates.

The in vitro activity of meropenem was compared with those of penicillin, ampicillin, cefuroxime, cetriaxone, cefotaxime, rifampicin, chloramphenicol, sulphadiazine and ciprofloxacin against 121 British meningococcal isolates by a microdilution method in Mueller-Hinton broth and by the E test. All meningococcal strains were susceptible to the agents except for ampicillin (88.4%), penicillin (88.4%), sulphadiazine (57.9%) and rifampicin (95%). The emergence of resistance problems among meningococcal isolates stresses the need for their constant monitoring and of the development of new agents. In this study we have shown that meropenem is highly active in vitro against Neisseria meningitidis. Recent studies have indicated that meropenem is highly active clinically and bacteriologically in the treatment of bacterial meningitis. Thus, the potentials of meropenem as meningococcal prophylactic and therapeutic agent needs to be fully evaluated.

Usefulness of rat-derived antigen in the serodiagnosis of Pneumocystis carinii infection.

Sera from patients with likely and possible Pneumocystis carinii pneumonia (PCP) on the basis of clinical information and laboratory investigations were tested by immunoblotting to assess the usefulness of trophozoites in the serodiagnosis of PCP. IgG antibodies to 50-60- kDa proteins were demonstrated with cyst antigen, but antibodies to additional proteins of 61, 70, 82, 95, 99 and 116 kDa were found with trophozoite antigen. These bands were not demonstrated with control sera. IgG antibody to the 116-kDa protein was found in 18 (46%) of 39 sera from patients with possible PCP compared with 5 (17%) of 30 sera from patients with likely PCP. There was no other significant difference between the two patient groups in detection of these proteins. Sera with higher indirect immunofluorescence assay (IFA) IgG titres were more likely to be immunoblot positive. Only 4 of 16 patients with likely PCP were IgG negative in the IFA; three of these were IgG immunoblot positive. In 4 of 10 patients with likely PCP and 6 of 15 patients with possible PCP, demonstration of IgM or IgA, or both, by IFA or immunoblotting provided evidence suggestive of current infection. This study confirms the usefulness of rat-derived antigen, especially trophozoite antigen, in PCP serology. The IgG IFA remains the most useful test, but IgM and IgA testing and immunoblotting can support the diagnosis.