Serial transverse enteroplasty (STEP) in case of short bowel syndrome: did we achieve our goal? A systematic review.

Surveys on Serial Transverse Enteroplasty (STEP) published in international literature (1 January 2003- 31 May 2021) were searched. Articles were included from 17 countries: 1/23 comparative and 22/23 cohort studies. STEP was performed on 308 patients: pediatrics, adults, and mixed ages. Pediatric group included 16 studies and the adult 6. Pre-STEP residual small bowell (SB) length for pediatrics and adults ranged from 18 to 26 cm and from 30 to 70 cm, respectively. Post-STEP increased SB length for pediatrics and adults ranged between 42 and 100% and 50% and 176%, respectively. For pediatrics, enteral autonomy was reached in 32.22% of cases, parenteral nutrition (PN) dependence was 36.11%, a repeated STEP procedure (Re-STEP) was needed in 17.22%, and a bowel transplant was performed in 6.11%. In adults, enteral autonomy was achieved in 52.38%, while PN dependence was 37.1%, and no Re-STEP or transplantation were required. For the mixed group, post-STEP bowel length increased from 2 to 50 cm, enteral autonomy was obtained in 43%, PN dependence was 57%, without reported Re-STEP or transplantation. Mortality rates were between 5.55% (pediatric) and 7.14% (adults). Preoperative length with preservation of ileocecal valve represented the main predictive factors to achieve enteral autonomy.

Inactivation of urease by 1,4-benzoquinone: chemistry at the protein surface.

The high activity of urease, a Ni(ii) enzyme, has several adverse effects on human health and agriculture, and its modulation needs the use of inhibitors. 1,4-Benzoquinone (BQ) irreversibly inactivates Sporosarcina pasteurii urease (SPU), with first order kinetics for both the inhibitor and the enzyme. This reaction is stoichiometrically quenched in the presence of sulphite. The 2.07 Å crystal structure of SPU bound to BQ shows the presence of a 1,4-hydroquinone moiety covalently bound to the thiol group of αCys322, a key residue found on the mobile flap regulating the substrate access to the active site. The 1.75 Å crystal structure obtained when sulphite is added to a solution of SPU previously incubated with BQ shows the presence of a 2,5-dihydroxy-benzenesulphonate moiety bound to the αCys322 thiol group. These data reveal how the active site cysteine reacts with a prototypical BQ moiety, found in a large number of natural substances potentially suitable to control the urease activity.

Protonation-state determination in proteins using high-resolution X-ray crystallography: effects of resolution and completeness.

A bond-distance analysis has been undertaken to determine the protonation states of ionizable amino acids in trypsin, subtilisin and lysozyme. The diffraction resolutions were 1.2 Šfor trypsin (97% complete, 12% H-atom visibility at 2.5σ), 1.26 Šfor subtilisin (100% complete, 11% H-atom visibility at 2.5σ) and 0.65 Šfor lysozyme (PDB entry 2vb1; 98% complete, 30% H-atom visibility at 3σ). These studies provide a wide diffraction resolution range for assessment. The bond-length e.s.d.s obtained are as small as 0.008 Šand thus provide an exceptional opportunity for bond-length analyses. The results indicate that useful information can be obtained from diffraction data at around 1.2-1.3 Šresolution and that minor increases in resolution can have significant effects on reducing the associated bond-length standard deviations. The protonation states in histidine residues were also considered; however, owing to the smaller differences between the protonated and deprotonated forms it is much more difficult to infer the protonation states of these residues. Not even the 0.65 Šresolution lysozyme structure provided the necessary accuracy to determine the protonation states of histidine.

The determination of protonation states in proteins.

The protonation states of aspartic acids and glutamic acids as well as histidine are investigated in four X-ray cases: Ni,Ca concanavalin A at 0.94 A, a thrombin-hirugen binary complex at 1.26 A resolution and two thrombin-hirugen-inhibitor ternary complexes at 1.32 and 1.39 A resolution. The truncation of the Ni,Ca concanavalin A data at various test resolutions between 0.94 and 1.50 A provided a test comparator for the ;unknown' thrombin-hirugen carboxylate bond lengths. The protonation states of aspartic acids and glutamic acids can be determined (on the basis of convincing evidence) even to the modest resolution of 1.20 A as exemplified by our X-ray crystal structure refinements of Ni and Mn concanavalin A and also as indicated in the 1.26 A structure of thrombin, both of which are reported here. The protonation-state indication of an Asp or a Glu is valid provided that the following criteria are met (in order of importance). (i) The acidic residue must have a single occupancy. (ii) Anisotropic refinement at a minimum diffraction resolution of 1.20 A (X-ray data-to-parameter ratio of approximately 3.5:1) is required. (iii) Both of the bond lengths must agree with the expectation (i.e. dictionary values), thus allowing some relaxation of the bond-distance standard uncertainties required to approximately 0.025 A for a '3sigma' determination or approximately 0.04 A for a '2sigma' determination, although some variation of the expected bond-distance values must be allowed according to the microenvironment of the hydrogen of interest. (iv) Although the F(o) - F(c) map peaks are most likely to be unreliable at the resolution range around 1.20 A, if admitted as evidence the peak at the hydrogen position must be greater than or equal to 2.5 sigma and in the correct geometry. (v) The atomic B factors need to be less than 10 A(2) for bond-length differentiation; furthermore, the C=O bond can also be expected to be observed with continuous 2F(o) - F(c) electron density and the C-OH bond with discontinuous electron density provided that the atomic B factors are less than approximately 20 A(2) and the contour level is increased. The final decisive option is to carry out more than one experiment, e.g. multiple X-ray crystallography experiments and ideally neutron crystallography. The complementary technique of neutron protein crystallography has provided evidence of the protonation states of histidine and acidic residues in concanavalin A and also the correct orientations of asparagine and glutamine side chains. Again, the truncation of the neutron data at various test resolutions between 2.5 and 3.0 A, even 3.25 and 3.75 A resolution, examines the limits of the neutron probe. These various studies indicate a widening of the scope of both X-ray and neutron probes in certain circumstances to elucidate the protonation states in proteins.

Acute changes in clinical parameters and thyroid function peripheral markers following L-T4 withdrawal in patients totally thyroidectomized for thyroid cancer.

After total thyroidectomy, differentiated thyroid cancer (DTC) patients have to undergo L-T4 withdrawal for measuring serum thyroglobulin and 131I whole-body scan (131I WBS) to evaluate residual/recurrent malignant disease. The aim of the present work was to study in these patients the effects of acute thyroid hormone deficiency on various target organs and tissues. Clinical parameters and thyroid function peripheral markers were evaluated in 20 DTC patients, both before and after L-T4 withdrawal. A 24-h urine collection, a fasting blood sample for laboratory examinations, a clinical score for hypothyroidism and cardiovascular, neurological and neuropsychological evaluations were carried out. After L-T4 withdrawal, the clinical score significantly increased, as well as total cholesterol, triglycerides, creatine kinase, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase, whereas SHBG, osteocalcin and urine hydroxyproline levels significantly decreased. The acute thyroid hormone deficiency caused a systolic dysfunction of the left ventricle associated with an increase in systemic vascular resistance without cardiac contractility alterations. A significant increase in the left ventricular mass and thickness was also observed. Carpal tunnel syndrome appeared in 30% of patients and a significant reduction in the immediate auditive memorization and in attentive performance was also detected. These observations indicate that acute hypothyroidism causes significant clinical alterations of peripheral tissue function. In the follow-up of DTC patients, therefore, L-T4 withdrawal procedure should be restricted to cases where the cost/benefit ratio is favorable. Alternative procedures, such as the use of recombinant human TSH, should be used whenever possible.

Synchrotron and neutron techniques in biological crystallography.

Synchrotron radiation (SR) techniques are continuously pushing the frontiers of wavelength range usage, smaller crystal sample size, larger protein molecular weight and complexity, as well as better diffraction resolution. The new research specialism of probing functional states directly in crystals, via time-resolved Laue and freeze trapping structural studies, has been developed, with a range of examples, based on research stretching over some 20 years. Overall, SR X-ray biological crystallography is complemented by neutron protein crystallographic studies aimed at cases where much more complete hydrogen details are needed involving synergistic developments between SR and neutron Laue methods. A big new potential exists in harnessing genome databases for targeting of new proteins for structural study. Structural examples in this tutorial review illustrate new chemistry learnt from biological macromolecules.

Structure of lobster apocrustacyanin A1 using softer X-rays.

The molecular basis of the camouflage colouration of marine crustacea is often provided by carotenoproteins. The blue colour of the lobster carapace, for example, is intricately associated with a multimacromolecular 16-mer complex of protein subunits each with a bound astaxanthin molecule. The protein subunits of crustacyanin fall into two distinct subfamilies, CRTC and CRTA. Here, the crystal structure solution of the A(1) protein of the CRTC subfamily is reported. The problematic nature of the structure solution of the CRTC proteins (both C(1) and A(1)) warranted consideration and the development of new approaches. Three putative disulfides per protein subunit were likely to exist based on molecular-homology modelling against known lipocalin protein structures. With two such subunits per crystallographic asymmetric unit, this direct approach was still difficult as it involved detecting a weak signal from these sulfurs and suggested the use of softer X-rays, combined with high data multiplicity, as reported previously [Chayen et al. (2000), Acta Cryst. D56, 1064-1066]. This paper now describes the structure solution of CRTC in the form of the A(1) dimer based on use of softer X-rays (2 A wavelength). The structure solution involved a xenon derivative with an optimized xenon L(I) edge f" signal and a native data set. The hand of the xenon SIROAS phases was determined by using the sulfur anomalous signal from a high-multiplicity native data set also recorded at 2 A wavelength. For refinement, a high-resolution data set was measured at short wavelength. All four data sets were collected at 100 K. The refined structure to 1.4 A resolution based on 60 276 reflections has an R factor of 17.7% and an R(free) of 22.9% (3137 reflections). The structure is that of a typical lipocalin, being closely related to insecticyanin, to bilin-binding protein and to retinol-binding protein. This A(1) monomer or dimer can now be used as a search motif in the structural studies of the oligomeric forms alpha- and beta-crustacyanins, which contain bound astaxanthin molecules.

Specific interaction of lipoate at the active site of rhodanese.

Dihydrolipoate is an acceptor of the rhodanese-bound sulfane sulfur atom, as shown by analysis of the elementary steps of the reaction catalyzed by rhodanese. The crystal structure of sulfur-substituted rhodanese complexed with the non-reactive oxidized form of lipoate has revealed that the compound is bound at the enzyme active site, with the dithiolane ring buried in the interior of the cavity and the carboxylic end pointing towards the solvent. One of the sulfur atoms of the ligand in the unproductive complex is relatively close to the sulfane sulfur bound to Cys-247, the sulfur that is transferred during the catalytic reaction. This mode of binding of lipoate is likely to mimic that of dihydrolipoate. The results presented here support the possible role of dihydrolipoate as sulfur-acceptor substrate of rhodanese in an enzymatic reaction that might serve to provide iron-sulfur proteins with inorganic sulfide.

Apocrustacyanin A1 from the lobster carotenoprotein alpha-crustacyanin: crystallization and initial X-ray analysis involving softer X-rays.

The A1 subunit of the carotenoprotein alpha-crustacyanin, isolated from lobster carapace, has been crystallized using the vapour-diffusion method. The crystals, grown in solutions of ammonium sulfate containing methylpentanediol (MPD), diffracted to 2. 0 A. The crystals are stable to radiation. The space group of the crystals is P2(1)2(1)2(1). The unit-cell parameters are a = 41.9, b = 80.7, c = 110.8 A. 'Standard structure determination' has been unsuccessful within this crustacyanin family. Instead, an approach based on the S atoms is being undertaken involving softer X-rays at the SRS, Daresbury.

NH2-terminal sequence truncation decreases the stability of bovine rhodanese, minimally perturbs its crystal structure, and enhances interaction with GroEL under native conditions.

The NH2-terminal sequence of rhodanese influences many of its properties, ranging from mitochondrial import to folding. Rhodanese truncated by >9 residues is degraded in Escherichia coli. Mutant enzymes with lesser truncations are recoverable and active, but they show altered active site reactivities (Trevino, R. J., Tsalkova, T., Dramer, G., Hardesty, B., Chirgwin, J. M., and Horowitz, P. M. (1998) J. Biol. Chem. 273, 27841-27847), suggesting that the NH2-terminal sequence stabilizes the overall structure. We tested aspects of the conformations of these shortened species. Intrinsic and probe fluorescence showed that truncation decreased stability and increased hydrophobic exposure, while near UV CD suggested altered tertiary structure. Under native conditions, truncated rhodanese bound to GroEL and was released and reactivated by adding ATP and GroES, suggesting equilibrium between native and non-native conformers. Furthermore, GroEL assisted folding of denatured mutants to the same extent as wild type, although at a reduced rate. X-ray crystallography showed that Delta1-7 crystallized isomorphously with wild type in polyethyleneglycol, and the structure was highly conserved. Thus, the missing NH2-terminal residues that contribute to global stability of the native structure in solution do not significantly alter contacts at the atomic level of the crystallized protein. The two-domain structure of rhodanese was not significantly altered by drastically different crystallization conditions or crystal packing suggesting rigidity of the native rhodanese domains and the stabilization of the interdomain interactions by the crystal environment. The results support a model in which loss of interactions near the rhodanese NH2 terminus does not distort the folded native structure but does facilitate the transition in solution to a molten globule state, which among other things, can interact with molecular chaperones.

Superiority of acceleration and acceleration time over pulsatility and resistance indices as screening tests for renal artery stenosis.

OBJECTIVE: To compare the accuracy of four echo-Doppler-derived velocimetric indices (pulsatility and resistance indices, acceleration and acceleration time) in detecting renal artery stenosis in hypertensive patients. PATIENTS AND METHODS: In 73 hospitalized patients with moderate-to-severe hypertension, 18 of whom had normal renal arteries and 55 renal artery stenosis (50-95%) either atherosclerotic (30 cases, five bilateral) or fibromuscular dysplasia (25 cases, two bilateral), we measured the four velocimetric indices using the lateral abdominal approach and sampling Doppler waveforms distally to the stenosis. The diagnostic accuracy of each index was calculated using as cut-off limit the ideal threshold determined with the receiver-operating characteristic curves. RESULTS: On average all of the indices were altered significantly in arteries with stenosis of both aetiologies with respect to normal arteries, the alterations of pulsatility and resistance indices being, however, less pronounced than those of acceleration and acceleration time, particularly in atherosclerotic stenosis. With the cut-off limits of 0.93, 0.59 and 7.4 m/s2 and 60 ms, respectively, for pulsatility and resistance indices, acceleration and acceleration time, their diagnostic accuracies were 80, 73, 93 and 92%. In stenotic arteries, only the acceleration time was correlated with the degree of arterial narrowing, whereas, in normal arteries, only pulsatility and resistance indices were directly correlated with the age of patients. CONCLUSIONS: Acceleration and acceleration time are more accurate indices than pulsatility and resistance to screen for renal artery stenosis, probably because their alterations are less attenuated by the counterbalancing effects of age and of atherosclerosis.

[Clinical evaluation of calcium-polycarbophil in the treatment of non-specific diarrhea]. / Valutazione clinica del calcio-policarbofilico nella terapia delle diarree non specifiche.

We performed a study on 10 patients aged between 26 and 54 males and females, affected by non-specific diarrhea. A single-blind clinical trial has been developed where Calcium-Polycarbophil was administered (2 cps t.i.d.) for a period of 8 weeks, half with placebo and half with drug in cross-over. No drop-out occurred. Number of evaluations, cramps and consistency of stools, have been evaluated before and after treatment. A definite decrease of evacuations per day and of cramps, when present, together with a higher consistency of stools, are reported when Calcium-Polycarbophil is administered, according to the favourable medical judgement. Haematochemical parameters, evaluated before, during and after the treatment didn't show any relevant variation, apart from slight increase (not statistically significant) of calcium both in blood and in urine). No other unwanted event has been detected. Hence, the high therapeutic index of Calcium-Polycarbophil makes it highly desirable in the treatment of diarrhea.

The code of ethics and the role of nurses: an historical perspective.

A retrospective on the concept of nursing's code of ethics as it was considered throughout our history. Cianci discusses its importance in the early days and why it has even broader implications in today's troubled times.

Effect of vitamin A, C, and E supplementation on rectal cell proliferation in patients with colorectal adenomas.

Studies suggest that cell proliferation abnormalities of the colorectal mucosa are associated with risk of neoplasia, and most cancers of the large bowel are thought to arise from adenomas. The results of other studies suggest that vitamins A, C, and E have chemopreventive efficacy against colon cancer in animal models. This study evaluates the effect of dietary vitamin supplementation on cell kinetics in uninvolved rectal mucosa in patients with colorectal adenomas. Twenty patients with colorectal adenomas were given vitamins A, C, and E for 6 months after complete polypectomy, and 21 patients with adenomas received placebo. In each patient, six biopsy specimens were taken from normal-appearing rectal mucosa before treatment and after 3 and 6 months of treatment and were incubated with tritiated thymidine ([3H]thymidine), and the [3H]thymidine-labeled cells were counted by use of autoradiography. Two parameters of cell proliferation were evaluated: 1) the ratio of the number of labeled cells to the total number of cells (thymidine labeling index) and 2) the ratio of the number of labeled cells in the upper 40% of the crypt to the total number of labeled cells in the crypt (phi h). The latter index reflects abnormal expansion of the proliferative compartment and is thought to be an intermediate biomarker of cancer risk. In patients receiving vitamins, phi h decreased progressively from baseline values, with increasing statistical significance (P less than .05 after 3 months, P less than .01 after 6 months). There was a statistically significant decrease in the thymidine labeling index in the 40% of the crypt near the mucosal surface, but the variation in the overall labeling index was not statistically significant. In the placebo group, we observed no statistically significant change in cell kinetics. These findings suggest that vitamin A, C, and E supplementation is effective in reducing abnormalities in cell kinetics that may indicate a precancerous condition. Before larger trials on chemoprevention of colorectal adenoma recurrence are conducted, additional studies are needed (a) to validate that cell kinetics is an intermediate biomarker, (b) to determine active agents, optimal dosage, and the relative efficacy of agents given alone and in combination, and (c) to test toxicity.

Plasma active and inactive renin and fetal complications in women with high risk pregnancies.

To examine whether the activation of the renin system, which occurs during pregnancy, may be relevant for the development and the outcome of the fetus, we measured active and inactive renin throughout gestation in 29 women having a pregnancy defined as "high risk" because of a clinical history of hypertension, nephropathy, and unexplained abortions. In 23 of these women who delivered full-term infants with normal weight and status, we found that active renin increased progressively from early pregnancy until the end of the second trimester and then declined slightly thereafter. In contrast, in the remaining six women who had fetal complications consisting of either signs of distress requiring cesarean section or growth retardation, the increase in active renin failed to occur. In all women the levels of inactive renin were more elevated throughout gestation than those observed in nonpregnant women, and were higher, although not significantly, in women without fetal complications than in those with fetal complications. Thus, a blunted activation of the renin system during pregnancy is associated with alteration in fetal development and may possibly contribute to it.

Iodine-125-digoxin radioimmunoassay: comparison of commercial kits.

Iodine-125-digoxin radioimmunoassay kits available from Abbott Diagnostics (AD), Dade Division (D), Schwarz/Mann (SM), and Clinical Assays (CA) were evaluated with respect to assay quality. The kit accuracies did not differ significantly at 2.0 ng/ml and the interassay coefficients of variation ranged from 9% (AD) to 21.4% (CA) The accuracy for all kits above 4 ng/ml is questionable, and since serum-dilution values correlated well with undiluted serum values, the dilution method of dose quantitation is preferable for levels above 4 ng/ml. Although all the kits were adequate, for evaluating digoxin at the 2ng/ml level, the Abott kit seems to be of slightly better quality.