Eat a live toad.
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Education, Nursing, Continuing↗
Biomedical subjects
J Mansfield
Publications and source records attributed to J Mansfield.
Practical phase identification by convergent beam electron diffraction.
The purpose of this article is to present a practical guide to the identification of phases in the analytical electron microscope with the aid of convergent beam electron diffraction. There is included a step-by-step approach to phase analysis, from the possible choices of the form of the specimen through how to explore reciprocal space in order to perform a full phase identification, either by symmetry analysis or by simple comparison of a pattern observed in the microscope with a previously recorded pattern (fingerprinting). There is a strong emphasis on practical hints and useful shortcuts.
Crystallography↗
Treatment with dexamethasone of androgen excess in adolescent patients.
Fourteen hirsute girls, ages 12 to 22 years (mean +/- SD: 17.2 +/- 2.6 years), in whom 21-hydroxylase deficiency was excluded by a 1-hour intravenous alpha 1-24 corticotropin test, were evaluated by a 4-day dexamethasone test and then treated with a bedtime dose of dexamethasone (0.5 mg in 10 patients, 0.25 mg in four) for 0.6 to 3.4 years (1.3 +/- 0.8 years). Hirsutism decreased in four patients, did not change in nine, and increased in one. Of the 10 patients with irregular menses, only three developed regular cycles while taking dexamethasone. During long-term dexamethasone therapy, serum levels of testosterone decreased from 102 +/- 22 to 72 +/- 27 ng/dL, free testosterone from 35 +/- 11 to 19 +/- 8 pg/mL, and dehydroepiandrosterone sulfate from 396 +/- 138 to 171 +/- 101 micrograms/dL. Although free testosterone decreased to less than 15 pg/mL in eight of 14 patients with the suppression test, only four patients had free testosterone levels less than 15 pg/mL during therapy. Two of the 14 patients have had no recurrence of hirsutism or increase in serum androgens after 28 and 29 months, respectively, after dexamethasone therapy was discontinued. Oral contraceptives were given to nine patients inadequately responsive to bedtime dexamethasone therapy. The mean percent decrease of testosterone and free testosterone levels during oral contraceptive therapy was significantly greater than during long-term treatment with dexamethasone, and hirsutism lessened in all. We conclude that a single bedtime dose of dexamethasone is satisfactory only in patients who maintain serum free testosterone values less than 15 pg/mL without side effects. For other patients, either another glucocorticoid or, in most cases, ovulation suppression should be prescribed for adolescents with progressive hirsutism and elevated androgen levels.
17-Ketosteroids↗
Communications. Tackling problems.
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England↗
The relationships of calculated percent body fat, sports participation, age, and place of residence on menstrual patterns in healthy adolescent girls at an independent New England high school.
A prospective study was undertaken to determine normal menstrual patterns in healthy girls in an independent high school and assess the effects of exercise (type and hours per day), age (chronologic and gynecologic), calculated estimate of body fat, and place of residence (boarding and day students) on menstrual function. Three hundred twenty-seven girls (means age 15.5 +/- 1.1 years) answered a questionnaire on menstrual history; 306 (93.6%) were postmenarchal and 21 (6.4%) premenarchal. Calculated estimate of percent body fat was significantly lower in premenarchal than postmenarchal girls (22.4% versus 27.3% p less than 0.0001). Ninety-three percent of adolescents reported flow lasting 4-7 days; 59.7% dysmenorrhea; and 63% premenstrual symptoms. There was no correlation between estimated body fat or hours per day of exercise and the regularity of menses, duration of flow, or dysmenorrhea. With the exception of gymnastics and dancing, sports participation had little or no impact on menstrual patterns. Follow up questionnaires and menstrual calendars were obtained from 87 girls eight to fifteen months after the initial questionnaires. All girls whose cycles had changed from regular to irregular were boarding students, confirming previous anecdotal reports that separation from home may be a significant stress for adolescents.
Adipose Tissue↗
Lumbar myelography today. Experience with metrizamide, a water-soluble, non-ionic contrast medium.
A clinical assessment of metrizamide (Amipaque) lumbar myelography in 150 patients is reported, and the adverse reactions encountered are presented and discussed. Minor adverse reactions--headache (48%), nausea (10%) and vomiting (7%)--were common, and the incidence reflected overseas experience. Severe headache occurred in a significant proportion of patients (20%), despite adequate hydration and the use of a small-gauge needle. There were no major adverse reactions such as epilepsy or severe muscle spasm. The study suggests that metrizamide is well tolerated, gives good anatomical demonstration and should replace iophendylate (Myodil) in this region. Recent reports of occasional, but sometimes severe, neurological complications indicate that further cautious assessment is required.
Adolescent↗
Growth of Salmonella on chilled meat.
Growth rates of a mixture of Salmonella serotypes inoculated on beef from a commercial abattoir were measured at chill temperatures. The minimum recorded mean generation times were 8.1 h at 10 degrees C; 5.2 h at 12.5 degrees C and 2.9 h at 15 degrees C. Growth did not occur at 7-8 degrees C. From these data the maximum extent of growth of Salmonella during storage of meat for different times at chill temperatures was calculated. Criteria for deciding safe handling temperatures for meat are discussed. Maintaining an internal temperature below 10 degrees C during the boning operation would be sufficient to safeguard public health requirements.
Animals↗
Infrared and Raman imaging of biological and biomimetic samples.
Established methods for imaging of biological or biomimetic samples, such as fluorescence and optical microscopy, magnetic resonance imaging (MRI), X-ray tomography or positron emission tomography (PET) are currently complemented by infrared (both near-IR and mid-IR) as well as Raman spectroscopic imaging, whether it be on a microscopic or macroscopic scale. These vibrational spectroscopic techniques provide a wealth of information without a priori knowledge of either the spectral data or the composition of the sample. Infrared radiation does not harm the organism, no electric potential needs to be applied, and the measurements are not influenced by electromagnetic fields. In addition, no extrinsic labeling or staining, which may perturb the system under investigation, has to be added. The immense volume of information contained in spectroscopic images requires multivariate analysis methodologies in order to effectively mine the chemical and spatial information contained within the data as well as to analyze a time-series of images in order to reveal the origin of a chemical or biochemical process. The promise and limitations of this new analytical tool are surveyed in this review.
Animals↗
Diagnosis of trisomy 21 in preimplantation embryos by single-cell DNA fingerprinting.
Many couples presenting for preimplantation genetic diagnosis (PGD) for a single gene disorder are of advanced reproductive age (>35 years) and have a greater chance of producing embryos with chromosomal aneuploidies. The most common chromosomal aneuploidy observed in newborns is trisomy 21, or Down's syndrome. Consequently, the availability of a highly reliable system that simultaneously detects the heritable gene disorder and trisomy 21 would be beneficial to couples at specific risk. A pentaplex chromosome 21 (Ch 21) single-cell DNA fingerprinting system was developed in a multiplex fluorescence polymerase chain reaction (FL-PCR) on single cells. High reliability and accuracy rates were observed, together with low allele dropout (ADO) and preferential amplification rates on diploid buccal cells, trisomy 21 buccal cells and blastomeres derived from Ch 21 aneuploid embryos. A combined multiplex FL-PCR format was optimized with the common cystic fibrosis delta F508 mutation and validated on single buccal cells from a carrier of the cystic fibrosis delta F508 mutation. This new test is a very powerful technique, which also allows confirmation of the embryo parentage and the identification of extraneous DNA contamination that could cause a misdiagnosis in PGD cases.
Blastocyst↗
Characterization of avrPphE, a gene for cultivar-specific avirulence from Pseudomonas syringae pv. phaseolicola which is physically linked to hrpY, a new hrp gene identified in the halo-blight bacterium.
The avirulence gene matching the R2 gene for resistance to halo-blight disease in Phaseolus was cloned and sequenced from race 4 strain 1302A of Pseudomonas syringae pv. phaseolicola. The predicted 41-kDa AvrPphE protein is hydrophilic, has no features that indicate function, and no similarity to other protein sequences. The promoter region of avrPphE contains a "harp box" motif. The gene was expressed more strongly in minimal than in nutrient-rich media. Lower concentrations of the phytoalexin phaseollin accumulated in tissue undergoing the hypersensitive reaction (HR) determined by avrPphE than by avrPphB. Homologs of avrPphE were detected in strains representing eight races of P. s. pv. phaseolicola including those virulent on cultivars with the R2 resistance gene, and in P. s. pv. tabaci but not in P. cichorii or P. s. pvs. coronafaciens, glycinea, maculicola, pisi, or syringae. Disruption of avrPphE prevented induction of the HR but did not appear to affect basic pathogenicity. Transposon mutagenesis and DNA sequencing showed that avrPphE was linked to hrpY a hrp locus identified at the left end of the hrp gene cluster. Sequence analysis showed that the region linked to avrPphE was very similar to DNA containing hrp genes from P. s. pv. syringae including hrpJ, hrpL, and hrpK.
Amino Acid Sequence↗
Gene-for-gene interactions between Pseudomonas syringae pv. phaseolicola and Phaseolus.
The gene for cultivar-specific avirulence to Phaseolus vulgaris cv. Tendergreen in races 3 and 4 of Pseudomonas syringae pv. phaseolicola was isolated and sequenced. Genomic clones from libraries of race 3 in pLAFR1 and race 4 in pLAFR3, which altered the phenotype of race 5 from virulent to avirulent in Tendergreen, were found to possess a common approximately 15-kb region of DNA that contained the determinant of avirulence. Subcloning and insertion mutagenesis with Tn1000 located an avirulence gene within a 1.4-kb BglII/HindIII DNA fragment in races 3 and 4. Comparison of the nucleotide sequences of regions of DNA that confer avirulence confirmed that both races have an identical gene for avirulence (designated avrPph3) comprising 801 base pairs (bp) and predicted to encode a cytoplasmic protein of 28,703 Da. A sequence, TGCAACCGAAT, 91% homologous to the motif found in promoter regions of avrB and avrD from P. s. pv. glycinea was located 89-99 bp upstream of the start of the open-reading frame 1. Hybridization experiments showed that avrPph3 was not plasmid-borne and was absent from isolates of P. s. pv. phaseolicola races 1, 2, 5, 6, 7, and 8, P. cichorii, P. s. pvs. coronafaciens, glycinea, maculicola, pisi, syringae, and tabaci. Cosegregation studies of crosses between cultivars resistant (Tendergreen) and susceptible (Canadian Wonder) to races 3 and 4 and transconjugants of race 5 confirmed that a gene-for-gene relationship controls specificity in the interaction between Tendergreen and races 3 and 4 of P. s. pv. phaseolicola.
Amino Acid Sequence↗