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Evidence for an actin binding helix in gelsolin segment 2; have homologous sequences in segments 1 and 2 of gelsolin evolved to divergent actin binding functions?

Gelsolin is built up of six homologous segments that perform different functions on actin. Segments 1 and 2, which are suggested to be highly similar in their overall folds, bind monomeric and filamentous actin respectively. A long alpha-helix in segment 1 forms the major contact site of this segment with actin. We show that sequence 197-226 of segment 2, equivalent to the region around the actin binding helix in segment 1, contains F-actin binding activity. Consequently, positionally similar parts of segment 1 and 2 are implicated in the actin contact and solvent exposed residues in these parts must have evolved differentially to meet their different actin binding properties.

Actins↗

Coordination sphere and structure of the Mn cluster of the oxygen-evolving complex in photosynthetic organisms.

The great similarity between the binding of Fe(II) and the high-affinity Mn-binding site in the Mn-depleted PSII membranes (Semin et al. (1996) FEBS Lett. 375, 223-226) suggests that the coordination sphere of Mn in PSII is also suitable for iron. A comparison is performed between the primary amino acid sequences of D1 and D2 and diiron-oxo enzymes with the function of oxygen activation. All conservative motifs (EXXH) and residues binding and stabilizing the diiron cluster in diiron-oxo enzymes have been found in the C-terminal domains of D1 and D2 polypeptides. On the basis of these sequence similarities we suggest a structural model for the manganese cluster in the oxygen-evolving complex.

Amino Acid Sequence↗

Effect of bicarbonate on the S2 multiline EPR signal of the oxygen-evolving complex in photosystem II membrane fragments.

Removal of bicarbonate from spinach photosystem II BBY particles by means of washing in a CO2-free medium results in the loss of their capability to accumulate the S2 multiline EPR signal upon continuous illumination at 190 K. Addition of 1 mM NaHCO3 before illumination leads to a 50-60% restoration of the multiline signal. Similarly, in BBY particles depleted of Mn by treatment with 1 M Tris-HCl (pH 8.0) and 0.5 M MgCl2, re-addition of MnCl2 in the presence of 1 mM NaHCO3 results in a partial restoration (approximately 30%) of the S2 multiline EPR signal of the Mn cluster, while in the absence of NaHCO3 no restoration is observed. The results provide further evidence that bicarbonate is essential for maintaining the Mn-containing oxygen-evolving complex of PS II in a functionally active form.

Bicarbonates↗

Endoscopic findings in hypertrophic pyloric stenosis: appearance in classic and evolving disease.

BACKGROUND: Hypertrophic pyloric stenosis (HPS) is the most common abdominal surgical disorder in infants. Although the majority of cases are diagnosed by ultrasound, equivocal cases may require endoscopy. This study was performed to assess the various endoscopic appearances of HPS in infants. METHODS: A prospective study comparing the endoscopic appearance of the antrum and pylorus of 18 children with HPS to 21 children in a normal control group. RESULTS: Antral or pyloric mucosal hypertrophy was visualized endoscopically in all 18 study patients. The degree of mucosal thickening varied depending on the age of presentation and duration of symptoms. Antral fold hypertrophy was first noted at 10 days of age, and in the oldest patient (4 months of age) a pyloric mass was noted. By comparison, 21 control infants had no evidence of antral or pyloric narrowing or mucosal thickening. CONCLUSIONS: Upper endoscopy can be a valuable adjunctive diagnostic tool in select cases of HPS when imaging tests are inconclusive or when infants present with clinical symptoms outside the typical age-time frame for HPS. Because HPS may evolve over time, it is important that the endoscopist recognize the different appearances of HPS.

Disease Progression↗

Evolving concepts in the management of colonic injury.

PURPOSE: The management of colonic injury has changed in recent years. This study sought to evaluate current surgical management of injuries to the colon in a busy urban trauma centre, in the light of our increasing confidence in primary repair and evolving understanding of the concepts and practice of damage control surgery. METHODS: A retrospective analysis was made of consecutive patients presenting with colonic injury from January 1 to December 31 1998. Patients without full-thickness lesions of the colon were excluded, as were patients who died within 24 h of admission. Demographic data, wounding patterns and clinical course were studied. RESULTS: One hundred twenty-seven patients were analyzed. Management without colostomy was achieved in 84% of cases. Patients who underwent diversion of the faecal stream had increased morbidity and hospital stay compared to equivalent patients who were repaired primarily. The important subgroup of patients who underwent damage control or abbreviated laparotomy is discussed. CONCLUSION: This study further strengthens the validity of direct repair or resection and primary anastomosis for colonic injury. Strategies to deal with the subgroup of patients at very high risk of postoperative complications are suggested.

Accidents, Traffic↗

Recognizing adolescents' 'evolving capacities' to exercise choice in reproductive healthcare.

All countries (except Somalia and the USA) have adopted the UN Convention on the Rights of the Child, which usually applies to individuals aged under 18 years. The Convention requires governments to 'respect the responsibilities, rights and duties of parents [or others acting as parents] ellipsis in a manner consistent with the evolving capacities of the child'. Many adolescents gain capacity to make decisions for themselves concerning reproductive and sexual health services, and to decide issues of confidentiality. Immature adolescents must be given usual protections. The Convention sets a legal limit on parental power to deny capable adolescents reproductive and sexual health services. The question whether an adolescent is a 'mature minor' must be decided by health service providers independently of parental judgment. The specific duties of government and health service providers to implement adolescent rights regarding their reproductive and sexual health needs are examined.

Adolescent↗

An evolving hierarchical family classification for glycosyltransferases.

Glycosyltransferases are a ubiquitous group of enzymes that catalyse the transfer of a sugar moiety from an activated sugar donor onto saccharide or non-saccharide acceptors. Although many glycosyltransferases catalyse chemically similar reactions, presumably through transition states with substantial oxocarbenium ion character, they display remarkable diversity in their donor, acceptor and product specificity and thereby generate a potentially infinite number of glycoconjugates, oligo- and polysaccharides. We have performed a comprehensive survey of glycosyltransferase-related sequences (over 7200 to date) and present here a classification of these enzymes akin to that proposed previously for glycoside hydrolases, into a hierarchical system of families, clans, and folds. This evolving classification rationalises structural and mechanistic investigation, harnesses information from a wide variety of related enzymes to inform cell biology and overcomes recurrent problems in the functional prediction of glycosyltransferase-related open-reading frames.

Amino Acid Motifs↗

The distribution of wearout over evolved reliability structures.

A multiple-integral equation, termed the wearout equation, describes the distribution of wearout (or aging) over evolved reliability structures, such as organisms and self-replicating machines, and thus statistically governs virtually all aging properties of the systems. The equation is applied to the computation of ab initio ("from the beginning") life tables for four natural populations of ungulates--wild boar, Dall sheep, African buffalo, and hippopotamus--which represent a broad range of survival characteristics. The good agreement of the ab initio and empirical tables, the best available for testing the theory, demonstrates the basic realism of the wearout equation. If the equation withstands further experimental testing, its analysis may provide insight into fundamental questions in the biology of aging.

Aging↗

Neoadjuvant chemotherapy in invasive bladder cancer: the evolving role of surgery.

The role of an operation in patients receiving neoadjuvant chemotherapy for clinically localized but invasive transitional cell carcinoma of the bladder currently is evolving. An operation is essential for case selection and evaluation of local response but it also contributes to bladder preservation and survival. The procedure that is necessary to select for and assess response to chemotherapy may itself alter the actual or proceed to evolution of invasive bladder cancer. Neoadjuvant chemotherapy is a reasonable therapeutic strategy in selected patients but it remains to be seen whether the results will prove to be superior to those achieved with standard endoscopic and open operations.

Antineoplastic Combined Chemotherapy Protocols↗

Evolved improvements in placement of the silicone gel prosthesis for post-prostatectomy incontinence.

During the last 2 1/2 years we have used the silicone gel prosthesis for 8 consecutive patients who were incontinent after prostatectomy. Although the prosthesis had to be replaced in 1 instance a satisfactory result has been obtained by each patient. We believe that with minimal patient selection successful results can be achieved in a large majority of such patients by implementing the evolved improvements in prosthesis placement: 1) use 4 serrated knee staples or George Washington modification to improve fixation, 2) release the urethral bulb from the central perineal tendon for better compression and 3) place the prosthesis higher on the ischiopubic rami. Avoidance of urethral erosion is the single most important aspect of the procedure and intraoperative urethral pressure profile may be helpful in this regard. Guidelines regarding the procedure, prosthesis injection and patient management are discussed briefly.

Gels↗

Evolving uses of laparoscopy in children.

As the technology evolves, the number of procedures that can be performed laparoscopically will continue to expand (Table 3). The impact on the field of pediatric surgery, which encompasses surgical oncology, gastrointestinal surgery, trauma, and gynecologic surgery, will be significant. There are several hurdles for the pediatric surgeon to overcome before beginning operative laparoscopy. The acquisition of the initial instrumentation is expensive, and the credentialing process may be time-consuming. And there remains a healthy suspicion on the part of many pediatric surgeons that these techniques represent a fad. We believe that operative laparoscopy has advantages and disadvantages. Some of the procedures require more time and are frequently tedious, thus trying the patience of the surgeon. It is difficult for experienced surgeons to subject themselves electively to the learning curve associated with a new procedure. While the benefits are mostly in the postoperative period, we believe exposure is vastly improved in obese patients. Patients appear to have less pain and postoperative ileus, and they may return to unrestricted activity sooner. We are still discovering which laparoscopic procedures can be done safely to the patient's advantage. Solving the dilemma of what procedures should be performed using laparoscopic techniques will require extensive experience and study, and minimally invasive surgery will be a subject of controversy and debate for many years. It is difficult to imagine that open cholecystectomy would once again become the standard. We predict that we will see a continued expansion in the types of procedures to be performed using minimal-access techniques. And in the future, we may have to justify our opening of a patient's abdomen when the procedure could have been performed laparoscopically, as is now the case for cholecystectomy in some areas of the country.

Appendectomy↗

The evaluation of isolated third nerve palsy revisited: an update on the evolving role of magnetic resonance, computed tomography, and catheter angiography.

The evaluation and management of the neurologically isolated third nerve palsy continues to evolve. The major concern for the clinician confronted with a patient with a third nerve palsy has been the exclusion of an intracranial aneurysm. The evolution of new imaging techniques, such as computed tomography angiography and magnetic resonance angiography, have provided new imaging options for clinicians. This article reviews the pertinent recent literature on the use of these imaging studies in evaluating the patient with a third nerve palsy.

Angiography↗

Evolving patterns of tissue composition in benign prostatic hyperplasia as a function of specimen size.

The tissue composition in 36 transurethral resections and four prostate enucleations for benign prostatic hyperplasia (BPH) was quantitated by computerized morphometric techniques using 15 morphologic categories. Data were compared between seven consecutive weight ranges. Nodules of glandular and/or stromal tissue comprised only 5% of tissue in the smallest resections, while bladder neck and anterior fibromuscular tissue represented more than half the specimen. Non-nodular prostatic tissue from the transition zone was the dominant resected component in all but the largest specimens (enucleations) where nodules comprised most of the tissue. Though nodules comprised only 22% of the largest transurethral resections, their contribution to hyperplasia increased more rapidly than any other component. Glandular nodules with a high ratio of epithelium to stroma dominated at all weight ranges. It was concluded that tissue resected for BPH is quite heterogeneous, that nodules comprise most of the tissue only in specimens over 50 g in weight, and that the most common hyperplastic component is histologically normal tissue. Benign prostatic hyperplasia undergoes morphologic evolution with increasing weight, and epithelial-rich nodules are the most rapidly evolving component.

Aged↗

Evolving concepts of cortical radial and areal specification.

The fundamental principles of cortical organization and its development, postulated by Santiago Ramón y Cajal at the turn of the century, based on his exquisite observations and ingenious interpretation of neuronal assemblies impregnated with the Golgi method, are being expanded with the application of advanced methods of anatomy, molecular biology and genetics. In this chapter, I will focus on the concept of columnar organization and areal specifications of the cerebral cortex that has served as a useful framework for understanding its development as well as its function as an evolving organ of thought.

Animals↗

Prostatitis: evolving management strategies.

Concepts regarding the etiology, diagnosis, and management of prostatitis have changed more in the last 3 years than they have in the last 3 decades. Urologists (and all physicians) no longer need to avoid patients with this disease. It is hoped that the new management strategies that are evolving will eventually benefit the majority of patients sustaining prostatitis.

Acute Disease↗

Consilience across evolving dysplasias affecting myeloid, cervical, esophageal, gastric and liver cells: common themes and emerging patterns.

In the present paper, an attempt is made to identify common biologic themes across dysplastic states affecting the marrow, gastro intestinal tissue, the cervix and liver as well as unifying patterns during disease evolution. The following algorithm appears generally applicable, although individual variations must necessarily be anticipated. It appears that there is an initial transforming event which in all dysplasias except that affecting the marrow has been found to be infectious. Increased cellular proliferation-increased apoptosis, telomere shortening, appearance of telomerase expression and clonal expansion follow the initial insult. Abnormalities in the cytokine environment are universally described and it is likely that the quintessential monoclonality aspect of dysplasia predisposes to accumulation of genetic mutations, and microsatellite instability leading to the appearance of evolved sub-clones. The conversion of a dysplastic phenotype to a malignant one reflects the success of one such sub-clone in developing a survival advantage over a large population of prematurely apoptotic neighbors. This state is usually acquired by silencing tumor suppressor genes through hypermethylation or actual loss or dysfunction. Thus, excessive apoptosis of cells resulting from a persistent infectious process predisposes the organ towards developing a cancerous phenotype. Evidence for the shared pathology is presented at length with the hope that these parallels between dysplastic states will be helpful in both biologic and therapeutic research.

Animals↗

Effects of lanthanide substitution at Ca2+-site on the properties of the oxygen evolving center of photosystem II.

Functional calcium present in a photosynthetic oxygen evolving center (OEC) was replaced by lanthanides. To this end, sample membranes depleted of Ca2+ as well as 16 and 24 kDa extrinsic proteins were prepared and the effects of lanthanides substitution on OEC were studied. The lanthanides inhibited Ca2+-dependent restoration of oxygen evolution but the presence of Ca2+ during the treatment protected OEC from this inhibition, which occurred within 1 min at 20 degrees C but required much longer time at 0 degrees C. Kinetic analysis suggests that lanthanides function as a mixed-type competitor for Ca2+. Lanthanides with ionic radii smaller than Ca2+ show higher affinity for the Ca2+ site than those with larger radii. A lanthanide-substituted OEC displayed a thermoluminescence (TL) band arising from S2Q(A)- charge recombination, indicating that the Mn cluster is oxidized to the S2 state. However, the peak temperature of the TL band varied depending on lanthanide species. The results indicate that the oxidation potential of the Mn cluster is modified in various ways in a substituted OEC. Furthermore, the threshold temperature for the S1 to S2 transition in the lanthanide-substituted OEC was markedly upshifted to the temperature coincident with that found in Ca2+-depleted but 24 kDa protein preserved OEC. Changes in the OEC induced by the binding of lanthanides to the Ca2+-site are discussed based on these results.

Calcium↗

Bacteraemic pneumococcal pneumonia: a continuously evolving disease.

During an 8 year prospective study of community-acquired pneumonia (CAP) requiring hospitalisation we found that 47 of 1118 (4.2%) patients had Streptococcus pneumoniae bacteraemia. Females outnumbered males 27:20. The mean age was 63.4 years and 25% of our patients were admitted from a nursing home. A comparison with the 1071 other patients with CAP showed that patients with bacteraemic pneumococcal pneumonia (BPP) were more likely to be female and to have alcoholism, diabetes mellitus, and chronic obstructive pulmonary disease as co-morbidities. The mortality rate of 19% in BPP was not significantly lower than the 22% rate for the remaining patients with CAP. Four of the nine (44%) patients with BPP who died, did so within 24 h of admission, compared with 29 of 236 (12.3%) (P less than 0.02) who died of CAP. A notable clinical feature was the absence of cough in 19% while overall in only 66% was the cough productive. Most of the patients had a non-specific clinical presentation. Fifty-three per cent had an uncomplicated stay in hospital. We conclude that bacteraemic pneumococcal pneumonia is a continuously evolving disease and for the first time may now be more common in women.

Bacteremia↗