Diffusion tensor imaging determines three-dimensional architecture of human cervix: a cross-sectional study.

OBJECTIVE: To determine the microarchitecture of the cervix using high-resolution diffusion tensor (DT) magnetic resonance imaging (MRI). DESIGN: Cross-sectional study. SETTING: Leeds, UK. SAMPLE: Women undergoing hysterectomy for benign pathology. METHODS: Ex-vivo DT-MRI measurements were obtained using a 9.4-T Bruker nuclear magnetic resonance (NMR) spectrometer on seven fixed human cervices obtained at hysterectomy. A deterministic fibre-tracking algorithm was used to indirectly visualise underlying fibre organisation. Inter-regional differences in tissue structure were sought using quantitative measurements of diffusion. MAIN OUTCOME MEASURE: The identification of an occlusive structure in the region corresponding to the internal cervical os. RESULTS: Fibre tracking demonstrated two regions: an outer circular and inner longitudinal layer. The total circumferential tract volume (TV) was greatest in the proximal region of the cervix (TV: proximal, 271 ± 198 mm3 ; middle, 186 ± 119 mm3 ; distal, 38 ± 36 mm3 ). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) measurements were significantly different between regions in all samples (P < 0.0005), indicating greater tract density and organisation towards the internal os. CONCLUSION: Fibre tracking infers a system of dense, well-defined, encircling fibres in the proximal region of the cervix, corresponding to the location of the internal os. These findings may provide evidence of specific anatomic microarchitecture within the cervix able to resist intrauterine forces associated with pregnancy. TWEETABLE ABSTRACT: Diffusion-tensor MRI derived tractography identified well-defined encircling fibres at the internal os.

Dissociation of multiply charged ICN by Coulomb explosion.

The fragmentations of iodine cyanide ions created with 2 to 8 positive charges by photoionization from inner shells with binding energies from 59 eV (I 4d) to ca. 900 eV (I 3p) have been examined by multi-electron and multi-ion coincidence spectroscopy with velocity map imaging ion capability. The charge distributions produced by hole formation in each shell are characterised and systematic effects of the number of charges and of initial charge localisation are found.

Subjective and objective outcomes of strabismus surgery in children.

BACKGROUND: The negative psychosocial impact of strabismus in adults has been well documented. Despite the increasingly recognized importance of outcomes research, parents' satisfaction with strabismus treatment in childhood and their assessment of its functional impact and "quality of life" impact have not been investigated. METHODS: A survey instrument was designed to assess parents' perceptions of preoperative, surgical, and postoperative phases of the clinical experience, including the long-term impact of surgery on their children. RESULTS: Overall satisfaction with the surgical result was rated "good" or "very good" in 85% of 77 children under age 6. The correlation between subjective satisfaction and objective alignment within 10 prism diopters (delta) of orthophoria was significant (P < .001). Parents of children under age 4 noted improved eye contact (61%) and appearance (94%). Parents of older children noted improved interactions with others (47%) and self-esteem (55%). Coordination was considered improved in 56% of the entire group. Subjective satisfaction and psychosocial benefits often occurred even in cases deemed objectively unsuccessful. CONCLUSION: Surgical correction of strabismus in childhood is clearly perceived by parents to be both successful and important to them and their children.

Exaggerated effect of bilateral medial rectus recession in developmentally delayed children.

Many have suggested that the esotropia associated with developmental delay should be considered separately. However, the esotropia surgery recommended for developmentally delayed children has been similar to that performed in normal children. We have noticed a tendency for developmentally delayed children to develop consecutive exotropia following bilateral medial rectus recessions. Of 94 children undergoing such surgery between 1981 and 1991, 31 were developmentally delayed. Follow up ranged from 7 months to 202 months (mean 24 months). Surgical effect, defined as the change in alignment following each amount of surgery, was greater in the developmentally delayed group than in control subjects (P = .002). The increase in effect of the same amount of surgery in a developmentally delayed patient averaged 5.28 prism diopters, but was much larger in specific instances. Variability of effect was more marked among developmentally delayed children. We conclude that bilateral medial rectus recessions in developmentally delayed children may be better postponed in some cases, deferred for smaller angles, or decreased in amount.

Alignment success following medical rectus recessions in normal and delayed children.

Others have suggested that developmentally delayed children, who are frequently esotropic, have a poor prognosis following esotropia surgery. To date, no comparison of success rates in normal and delayed children following similar surgery has been made. We compared our long-term results following graded bilateral medial rectus recessions in consecutive normal (n = 62) and delayed (n = 29) children. We defined success as alignment maintained within 10 delta of orthophoria. Survival curves were compared using the Mantel-Haenszel statistic. Delayed children had a significantly poorer outcome (p = .05) throughout follow up, which ranged from 12 to 120 months (mean = 24 months). Early in the period of study, we observed a large proportion of overcorrections among the delayed children. Subsequent modification in the amount of surgery performed appeared to improve the initial and long-term success in these children. We conclude that delayed children do have a poorer prognosis than normal children following medial rectus recession. This prognosis may be improved by more conservative amounts of surgery.

Steroid injection versus conservative treatment of anisometropia amblyopia in juvenile adnexal hemangioma.

Because of serious side effects, the indications for intralesional steroid injection of adnexal hemangiomas are unclear. Of 23 children with such lesions who were examined over a period of 9 years, 9 had no evidence of amblyopia and needed no intervention. Five required steroids intralesionally and/or systemically because of threatened occlusion of the pupillary axis. The remaining 9 were considered at risk of anisometropic amblyopia because of induced astigmatism: 5 received injections and 4 were treated with glasses and/or patching alone. The visual, refractive, and cosmetic results of the injected and conservatively managed anisometropes were similar. We recommend that steroid injection be reserved for patients with threatened occlusion of the visual axis and for those with severe astigmatism or amblyopia refractory to conservative management.

The nature of the proteins in 'chloramphenicol particles' from Escherichia coli A19 (Hfr rel met rns).

The unusual particles which accumulate in cell-free extracts from Escherichia coli A19 during chloramphenicol inhibition ('chloramphenicol particles') have been isolated by large-scale rate-zonal density gradient ultracentrifugation. The proteins and RNA species composing these particles have been examined. The rRNA species present are precursor and mature forms of 16S and 23S rRNA which accumulate during inhibition. The proteins prepared directly from the particles give strong multiple immunoprecipitates with antisera specific to 30S and 50S ribosomal proteins. The soluble proteins of the cell prepared in the same manner do not give this immunological reaction. Two-dimensional electrophoresis patterns of the proteins from the 'chloramphenicol particles' strongly resemble those for 30S and 50S ribosomal proteins, i.e. they are predominantly basic low molecular weight proteins, and are dissimilar to the patterns for the soluble proteins of the cell. It is concluded that the 'chloramphenicol particles' are a heterogeneous group of ribonucleoproteins comprising the bulk of the rRNA accumulating during inhibition in association with variable amounts of some of their corresponding ribosomal proteins. The particles are therefore not artefacts of preparation, as previously thought, but arrested ribosome precursors.

The nature of the proteins present in the 'relaxed particles' from methionine-starved Escherichia coli A19 (Hfr rel met rns).

The 'relaxed particles' formed during methionine starvation of Escherichia coli A19 (Hfr rel met rns) have been isolated by large-scale rate-zonal density gradient ultracentrifugation. The proteins and rRNA species associated with these particles have been examined. The rRNA species present are precursor and mature forms of 16S and 23S rRNA. The bulk of the rRNA which accumulates during starvation is found within the particles. The proteins prepared directly from the particles give strong multiple immunoprecipitates with antisera specific to 30S and 50S ribosomal proteins. The soluble proteins, prepared and examined in the same manner, do not give this immunological reaction. Two-dimensional electrophoresis patterns of the proteins from the particles show that the proteins co-migrate with proteins from 30S and 50S ribosomes and are entirely dissimilar to the proteins prepared by the same methods from the soluble fraction of the cells. On the basis of these and other observations, it is concluded that the 'relaxed particles' are not artefacts but are arrested ribosome precursors containing both rRNA and certain ribosomal proteins. The free pool of ribosomal proteins is low in exponential-phase cells and is not significantly increased by a 2 h period of starvation for glucose. The implications of these observations concerning the proteins associated with 'relaxed' and 'chloramphenicol particles' are discussed in raltion to ribosome biogenesis and the stabilization of rRNA.

Pi (antitrypsin) typing methods. A comparison of acid starch-gel electrophoresis and isoelectric focusing.

The Pi typing methods acid starch-gel electrophoresis (ASGE) and isoelectric focusing (IEF) have been compared by three reference laboratories: 564 samples of phenotypes Pi M, MS and MZ were tested in each of the three laboratories with a 96% agreement on initial typing. The discrepancies are recorded and reasons for disagreement discussed. IEF is a reliable method for Pi typing and gives results comparable to those obtained by ASGE.