Burkholderia pseudomallei multi-centre study to establish EUCAST MIC and zone diameter distributions and epidemiological cut-off values.

OBJECTIVES: Melioidosis, caused by Burkholderia pseudomallei, requires intensive antimicrobial treatment. However, standardized antimicrobial susceptibility testing (AST) methodology based on modern principles for determining breakpoints and ascertaining performance of methods are lacking for B. pseudomallei. This study aimed to establish MIC and zone diameter distributions on which to set epidemiological cut-off (ECOFF) values for B. pseudomallei using standard EUCAST methodology for non-fastidious organisms. METHODS: Non-consecutive, non-duplicate clinical B. pseudomallei isolates (9-70 per centre) were tested at eight study centres against eight antimicrobials by broth microdilution (BMD) and the EUCAST disc diffusion method. Isolates without and with suspected resistance mechanisms were deliberately selected. The EUCAST Development Laboratory ensured the quality of study materials, and provided guidance on performance of the tests and interpretation of results. Aggregated results were analysed according to EUCAST recommendations to determine ECOFFs. RESULTS: MIC and zone diameter distributions were generated using BMD and disc diffusion results obtained for 361 B. pseudomallei isolates. MIC and zone diameter ECOFFs (mg/L; mm) were determined for amoxicillin-clavulanic acid (8; 22), ceftazidime (8; 22), imipenem (2; 29), meropenem (2; 26), doxycycline (2; none), tetracycline (8; 23), chloramphenicol (8; 22) and trimethoprim-sulfamethoxazole (4; 28). CONCLUSIONS: We have validated the use of standard BMD and disc diffusion methodology for AST of B. pseudomallei. The MIC and zone diameter distributions generated in this study allowed us to establish MIC and zone diameter ECOFFs for the antimicrobials studied. These ECOFFs served as background data for EUCAST to set clinical MIC and zone diameter breakpoints for B. pseudomallei.

Microprocessors: from desktops to supercomputers.

Continuing improvements in integrated circuit technology and computer architecture have driven microprocessors to performance levels that rival those of supercomputers-at a fraction of the price. The use of sophisticated memory hierarchies enables microprocessor-based machines to have very large memories built from commodity dynamic random access memory while retaining the high bandwidth and low access time needed in a high-performance machine. Parallel processors composed of these high-performance microprocessors are becoming the supercomputing technology of choice for scientific and engineering applications. The challenges for these new supercomputers have been in developing multiprocessor architectures that are easy to program and that deliver high performance without extraordinary programming efforts by users. Recent progress in multiprocessor architecture has led to ways to meet these challenges.

Small shared-memory multiprocessors.

Multiprocessors built from today's microprocessors are economically attractive. Although we can use these multiprocessors for time-sharing applications, it would be preferable to use them as true parallel processors. One key to achieving efficient parallel processing is to match the communications capabilities of the multiprocessor to the communications needs of the problem. The other key is improved parallel programming systems. If these are achieved, then efficient parallel processing can be approached from both ends by providing more communications capability in the hardware and restructuring the problem to reduce the communications requirements.

Natural variation in a Drosophila clock gene and temperature compensation.

The threonine-glycine (Thr-Gly) encoding repeat within the clock gene period of Drosophila melanogaster is polymorphic in length. The two major variants (Thr-Gly)17 and (Thr-Gly)20 are distributed as a highly significant latitudinal cline in Europe and North Africa. Thr-Gly length variation from both wild-caught and transgenic individuals is related to the flies' ability to maintain a circadian period at different temperatures. This phenomenon provides a selective explanation for the geographical distribution of Thr-Gly lengths and gives a rare glimpse of the interplay between molecular polymorphism, behavior, population biology, and natural selection.

Temporal mating isolation driven by a behavioral gene in Drosophila.

Speciation is the evolutionary process in which new barriers to gene exchange are created. These barriers may be physical, leading to spatial separation of subpopulations and resulting in allopatric speciation, or they may be temporal, giving rise to allochronic speciation, and may include the time of day or the time of year when mating takes place. Drosophila melanogaster and D. pseudoobscura show different temporal patterns of circadian locomotor activity that are determined by the circadian clock gene period (per). Genes that control aspects of behavior that might be relevant to courtship and mating, such as locomotor patterns, become obvious candidates for involvement in the speciation process. However, evidence for the role of individual genes in the mechanism of mate choice has proved elusive. We have used transgenic flies carrying the natural per genes from these two Drosophila species to reveal that per has the potential to provide the permissive conditions for speciation, by affecting mate choice through a mechanism involving the species-specific timing of mating behavior.

Development of a new melanoma model in C57BL/6 mice.

In the present study, we induced melanomas in C57BL/6 mice by a single application of 7,12-dimethylbenz(a)anthracene to the scapular region of 4-day-old mice, followed by twice-weekly applications of croton oil. Of 20 mice treated, melanomas arose in two female littermates. The first melanoma (JB/MS) arose 16 weeks after initiation of treatment, and the second melanoma (JB/RH) arose 23 weeks later. The melanomas maintained their melanotic appearance after s.c. transplantation to normal C57BL/6 mice and metastasized spontaneously in the transplant recipients. To our knowledge, these are the first melanomas to have been induced in C57BL/6 mice since the B16 melanoma arose spontaneously in 1954. We feel that the JB/MS and JB/RH melanomas provide an excellent comparative system for studies done with the B16 melanoma. These melanomas of recent origin will also facilitate the investigation of biological, immunological, and biochemical parameters that influence the growth and metastasis of malignant melanomas.

Jodbasedow and thyrotoxic periodic paralysis.

A 37-year-old white man with a multinodular goiter had thyrotoxicosis develop after iodine administration (Jodbasedow). His hyperthyroid state was accompanied by thyrotoxic periodic paralysis, a complication of hyperthyroidism that is usually seen in Orientals. The patient manifested typical features of each disorder. As classically described, these two thyroid-related disorders should rarely coexist because of epidemiologic considerations; however, the population at risk may be greater than has generally been appreciated.

Vascular tissue (Na,K)ATPase activity and aging in the F344 rat.

Vascular tissue (heart, thoracic aorta and tail artery) was removed from Fischer 344 rats, 12, 18 and 27 months of age. The intact tissue was then used to determine total, ouabain-sensitive and ouabain-insensitive 86Rubidium (86Rb) uptakes, to provide a reflection of (Na,K)ATPase activity. These studies indicate no change in total, ouabain-sensitive nor ouabain-insensitive 86Rb uptakes into cardiac tissue isolated from these rats. However, tail artery total and ouabain-sensitive 86Rb uptake decreased with age (a 61% decrease in ouabain-sensitive 86Rb uptake in 12 vs. 27-month-old rats) without significant changes in the ouabain-insensitive 86Rb uptake. This pattern was repeated in aortic tissue with a 56% decrease in ouabain-sensitive 86Rb uptake in 12 vs. 27-month-old rats. The results of these studies support an age-related decline in (Na,K)ATPase activity in aortic and tail artery tissue without a significant change in cardiac (Na,K)ATPase activity between 12, 18 and 27-month-old Fischer 344 rats.

New Marfanoid syndrome with craniosynostosis.

We report on a patient with various connective tissue abnormalities suggesting a distinctive disorder combining some features of the Marfan syndrome with craniosynostosis and other anomalies. A comparison is made with the Marfan syndrome and other phenotypically similar conditions.

Expanding the phenotype of the Proteus syndrome: a severely affected patient with new findings.

Here we report on a boy who died at 16 1/2 months with hemihypertrophy, eye abnormalities, macrodactyly, hamartomas, pigmented nevi, cerebral involvement, and other anomalies compatible with the Proteus syndrome. In addition, he also had abnormalities previously unreported in the Proteus syndrome including craniosynostosis and complex congenital heart defects. He seems to represent an extremely severe form of the Proteus syndrome and expands the already broad range of the phenotype.

Erythrocyte sodium concentration and 86Rb uptake in weanling Dahl rats.

Alterations in Na, K ATPase pump activity as well as erythrocyte (RBC) intracellular sodium concentration (Nai) have been demonstrated in humans and rats with established hypertension. The contribution of hypertension itself to these changes is unclear. Accordingly, we investigated RBC ion transport and plasma ouabain-like factor (OLF) in four- to five-week old normotensive Dahl salt-sensitive (DS) and salt-resistant (DR) rats on low salt diet. Although both strains were normotensive, systolic blood pressure (SBP) of DS (123 +/- 2 mm Hg) was higher than that of DR (116 +/- 1 mm Hg). No interstrain difference was evident in RBC pump activity measured as ouabain-sensitive 86rubidium (86Rb) uptake (DS = 0.277 +/- .030 and DR = 0.271 +/- .029 mumol/10(9)RBC/h) even though RBC Nai was greater in DS than DR (14.9 +/- 2.0 v 10.7 +/- 1.0 mEq/L; P less than 0.05). Plasma OLF was higher in DS than DR (28.9 +/- 4.7 v 16.5 +/- 2.3 pmol/mL; P less than 0.05), but did not correlate with RBC pump activity in either strain. RBC Nai was directly correlated with pump activity in DS (r = 0.84, P less than 0.01) and demonstrated a trend to correlate in DR (r = 0.71, P = 0.07). RBC Nai was also directly correlated with SBP in DR (r = 0.73, P less than 0.05) and DS (r = 0.70, P = 0.05). We conclude that RBC Nai is genetically determined in Dahl rats and is elevated in normotensive DS who are at risk for hypertension development.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigenic shifts in serotype determinants of Campylobacter coli are accompanied by changes in the chromosomal DNA restriction endonuclease digestion pattern.

Changes in somatic (O) lipopolysaccharide (LPS) antigenic specificities of Campylobacter coli serostrains were observed after continuous laboratory subculture. Two serostrains (C. coli O34 and C. coli O48) lost O specificity and did not react with homologous or any of the available heterologous antisera. The C. coli serostrain for serogroup O5, after subculture, yielded a variant that had acquired a new specificity which was detectable with a heterologous antiserum. In a repeat experiment with the original isolate of the O5 strain, a second variant was obtained which had not only acquired the same new determinant but had, unlike the first variant, lost reactivity with the homologous antiserum. Immunoblot experiments with homologous and heterologous antisera indicated that changes in antigenic specificity were associated with the O side chains of the LPS molecules. Results of restriction endonuclease analysis of chromosomal DNA of the variants and their parents revealed minor differences in restriction patterns which suggested that C. coli is capable of undergoing genomic re-arrangements that lead to changes in LPS specificity and structure.

Plasma corticosterone levels as an index of the strength of illness induced taste aversions.

Data are presented which demonstrate the task generality of pituitary-adrenal changes that accompany avoidance conditioning. In two experiments a conditioned aversion to milk was established by pairing it with lithium chloride (LiCl). In Experiment 1 conditioned pituitary-adrenal activation occurred when, in a conflict situation, animals reexperienced milk that had earlier been paired with LiCl. The relationship between the strength of aversion and corticosterone levels was such that animals showing the greatest avoidance showed the largest elevations in plasma corticosterone. In Experiment 2 this behavior/steroid relationship was manipulated. Dexamethasone (DEX) pretreatment on the day of conditioning was used to attenuate the conditioned aversion. Compared to saline (SAL) controls when reexposed to milk, DEX animals showed an attenuated aversion (i.e., drank more) and a smaller conditioned response (i.e., less adrenocortical activity). The reduction of conditioned elevation in corticosterone was not due to any residual effects of DEX at the time of testing (Experiment 3). Plasma levels of corticosterone represent an index for assessing the strength of illness induced conditioned taste aversions.

Racial differences in intact erythrocyte ion transport.

Epidemiologic studies indicate a much higher incidence of hypertension in blacks than in whites, although no clear biochemical correlates to account for such overt racial differences have been identified. In recent years, considerable evidence has linked perturbations in ion transport to the risk of developing hypertension. Potassium (K+) transport and the ouabain-sensitive component of K+ transport in the erythrocyte were measured in 54 healthy, age and sex matched black and white subjects. Blacks have a significantly (p less than 0.001) lower capacity for K+ transport (0.190 +/- 0.03 mumoles K+ per hr per 10(9) red blood cells [RBC] than whites (0.230 +/- 0.03 mumoles K+ per hr 10(9) RBC) with a significantly (p less than 0.001) higher percentage of K+ transport dependent upon ouabain-sensitive mechanisms (blacks 85.26 +/- 4.14 percent versus whites 76.69 +/- 6.67 percent). These data clearly define overt racial differences in K+ transport which suggest that blacks have a more limited capacity to exchange intracellular sodium for extracellular K+, and a higher percentage of that exchange is dependent upon ouabain-sensitive mechanisms. These findings need be kept in mind were clinical studies of ion transport are being assessed and may be germane to the increased prevalence in blacks for the development of hypertension.

Measurement of active ion transport in man. Utilizing intact human erythrocytes.

Alterations in ion transport have been implicated in the pathogenesis of several disease states. Methods of studying ion transport, however, are rather tedious, time consuming and not well defined in terms of kinetics and reproducibility. This paper describes a rapid, simple method of examining ion transport in intact human erythrocytes utilizing 86rubidium as a tracer. Twelve normal subjects were studied utilizing this method. Kinetic studies were performed from which maximal velocity (V max), a substrate concentration required to achieve half-maximal activity (Km), and a measure of the Ouabain sensitive component were determined for each subject and for the population. Additionally, five subjects underwent a repeat study at varying intervals up to 11 weeks. The results proved to be highly reproducible for each subject. It is suggested that the present technique offers not only speed and simplicity but yields kinetic data that is highly reproducible. Such advantages would make the techniques described ideal for studies desiring to compare age matched controls to subjects with intercurrent disease.

Psychosocial benefits of postmastectomy lymphedema therapy.

The effect of a comprehensive lymphedema management program was assessed in 25 patients in whom moderate to severe lymphedema had developed after surgery and/or radiotherapy for carcinoma of the breast. Intensive treatment (4 weeks) involved massage, compression bandaging, and sequential pneumatic compression, with an adjunct program of education to provide skills in exercise, massage, bandage, and containment garment use. The intensive treatment phase was followed by a self-management phase based on the skills that had been acquired. A significant reduction in limb circumference and volume, with continuing improvement over 12 months of self-management, was observed. There was a decrease in need for physical assistance. Quality of life generally remained high and stable throughout the 12 months. Quality of life specific to lymphedema, however, declined during the intensive phase of treatment, but recovered and surpassed pretreatment levels during the self-management phase of treatment. Perceived comfort and strength in the lymphedematous limb improved, and perceived size decreased. The study confirmed that the combination of multimodal physical therapy and education for self-management reduces lymphedema and its adverse subjective consequences and maintains the improvement thus achieved.

A mosaic cell layer in human pregnancy.

We present evidence for a novel histological and embryological relationship at the human materno-fetal interface. Here an epi- endo- thelium forms an integrated unicellular layer lining the intervillus space in between the anchoring villi that attach the placenta to the uterus. This layer appears to be derived from two different germ layers (mesoderm and ectoderm). The data presented here reveals that when a probe for the Y-chromosome is used to test the gender of placental cells following the birth of male or female babies, the cell-sheet is a genetic mosaic derived from two individuals (mother and baby). The endothelium is maternally derived; the epithelium is fetal derived. This new allo- epi- endothelium model is relevant to theories of germ layer separation in development, reproductive immunology and the endocrinology of implantation and placentation. It demonstrates cooperative intercellular interactions that are fundamental to achieving a major goal of human interstitial implantation the establishment of a blood sinus for haematotrophic nutrition. Poor implantation is a fundamental cause of pregnancy pathology and this knowledge will be useful in development of our understanding of pregnancy diseases.