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Does the sheep mandible relapse following lengthening by distraction osteogenesis?

AIM: Distraction osteogenesis is a technique used to lengthen the shortened mandible. However, the long term stability of the distracted mandibular bone is not known. The aim of this study was to assess if the sheep mandible relapses following lengthening, and to assess the quality of distracted bone up to 1 year post lengthening. METHODS: Twenty-four sheep had bilateral external mandibular distractors applied, with three sheep as controls. Titanium marker screws were positioned both proximal and distal to the distraction zone in all sheep. Following a 5 day latency period, the interdental gap was distracted 1 mm/day for 20 days, with a subsequent 20 day consolidation period. Ante-mortem serial X-rays were used to assess for relapse by measuring the distance between the screws. The animals were sacrificed at either 3, 6, 9 or 12 months post-distraction. At post mortem, the distance between the screws was re-measured. The distracted bone was assessed mechanically and histologically. RESULTS: The mean mandibular lengthening obtained was 13.2 mm. There was no relapse of the mandible over 12 months. The distracted bone had attained the strength and stiffness of undistracted bone by 6 months post-distraction (p < 0.05). Histological evaluation revealed significant amounts of lamellar bone by 6 months post-distraction. CONCLUSIONS: No relapse occurred for 12 months post distraction lengthening. The bone formed following distraction was stable and of good quality. These findings lend support to the use of distraction osteogenesis in clinical practice.

Analysis of Variance↗

Long-term follow-up in children treated for retroperitoneal malignant tumours.

Thirty-two long-term survivors after treatment with surgery, radiotherapy and chemotherapy for neuroblastoma (NRB) and Wilms' tumour (WT) were re-evaluated after a period of more than 10 years (mean 16 yr 1 mo, range 27 yr 2 mo/10 yr 5 mo). In addition to routine clinical and laboratory studies, all patients underwent auxometry, echocardiography, spinal X-ray, abdominal US and kidney radionuclide scans. Neither obvious physical signs nor cutaneous toxicity were noted at inspection. No dysmenorrhoea or sexual disorders were mentioned. Haematological data turned out to be all in the normal range, except for TIBC/UIBC ratio (out of range in 70 % of cases); gammaGt (62.5 %); A/G ratio (12.5 %); ALT (37.5 %). Auxometrical data were all in the normal range; in particular, results of mean weight and height were just slightly over the 50 degrees centile. Spinal X-rays revealed mild kyphotic deformities (68.9 %), pelvic obliquity and tilting (62.5 %), rotation of the vertebral bodies (34.3 %) and compensatory curves of the spine (21.8 %). No impairment of cardiac functions was noted at echocardiography. No alteration of the hepatic structure was detectable at US scans. Marked impairment of the renal function (20 % and 1.5 % residual function) was detected at radionuclide imaging in 2 NRB patients who had not undergone nephrectomy, with the kidney having almost disappeared in one. In conclusion, the study emphasises the need for careful and prolonged follow-up for the detection of sequelae than can appear even many years after the initial treatment, and the wisdom and the need for a continued search for less aggressive protocols; as long as the cure rate is not compromised, less aggressive protocols should aim for a satisfactory overall survival with a reduced incidence of sequelae and hence a better quality of life.

Adolescent↗

Serpin polymerization is prevented by a hydrogen bond network that is centered on his-334 and stabilized by glycerol.

Polymerization of serpins commonly results from mutations in the shutter region underlying the bifurcation of strands 3 and 5 of the A-sheet, with entry beyond this point being barred by a H-bond network centered on His-334. Exposure of this histidine in antithrombin, which has a partially opened sheet, allows polymerization and peptide insertion to occur at pH 6 or less when His-334 will be predictably protonated with disruption of the H-bond network. Similarly, thermal stability of antithrombin is pH-dependent with a single unfolding transition at pH 6, but there is no such transition when His-334 is buried by a fully closed A-sheet in heparin-complexed antithrombin or in alpha(1)-antitrypsin. Replacement of His-334 in alpha(1)-antitrypsin by a serine or alanine at pH 7.4 results in the same polymerization and loop-peptide acceptance observed with antithrombin at low pH. The critical role of His-334 and the re-formation of its H-bond network by the conserved P8 threonine, on the full insertion of strand 4, are relevant for the design of therapeutic blocking agents. This is highlighted here by the crystallographic demonstration that glycerol, which at high concentrations blocks polymerization, can replace the P8 threonine and re-form the disrupted H-bond network with His-334.

Antithrombins↗

Parapharyngeal extension of a meningioma.

A case of posterior fossa meningioma with parapharyngeal extension is described. The tumour lacked contrast enhancement at both CT and MRI, and showed no vascularity at angiography. These negative features restricted us to a differential diagnosis alone. The postulated mechanisms for an extracranial position of a meningioma, mainly from Hoye et al, are re-presented.

Cranial Fossa, Posterior↗

Reliability of skinfold calipers as a tool for measuring body fat in human beings.

Triceps skinfold thickness measured in ten adults aged 19 to 50 yr by a Holtain skinfold caliper, was compared with subcutaneous fat thickness obtained on cross-sections of the left upper arm by computerized axial tomography (CAT). The thickness of subcutaneous fat was measured on CAT scan film directly with the inbuilt computer graphic technique. The measurements taken on CAT scan film were found to be significantly higher (by 21-45%; P less than 0.001) than those by the skinfold calipers. Our findings suggest that skinfold calipers may not be very accurate tools for the assessment of body fat in human beings. Therefore, its use in the determination of body composition, for which great precision is required calls for re-thinking.

Adipose Tissue↗

[Primary hyperparathyroidism: significance of its preoperative localization].

The diagnostic accuracy of locating parathyroid tumors preoperatively was studied by reviewing 27 cases of hyperparathyroidism experienced at our Department between 1965 and 1983. Computed tomography gave the most accurate prediction (69%), followed by venous sampling for PTH (33%), subtraction scintigraphy with 201T1 and 123I (30%), ultrasonography (29%) and palpation (7%). Although the time required for an operation was not changed, significantly fewer parathyroid glands identified were removed during the operation when they had been located accurately before operation. This enabled quick recovery from postoperative hypocalcemia and ensured a safer operation. Scintigraphy and ultrasonography must first be performed in patients suspected of having hyperparathyroidism, but computed tomography is essential before operation. Venous sampling is indicated only when all other tests are negative, or in cases of re-operation.

Adolescent↗

[Traumatic hip dislocation with "spontaneous" reposition and re-luxation].

A case of traumatic hip dislocation with spontaneous reduction of the hip joint is presented. The patient was involved in a car accident, and characterized as multitraumatized. On admission to the Emergency Department there were no clinical signs of traumatic hip-dislocation, but because of the severity of the trauma an X-ray of the pelvis was performed and a fracture of the acetabulum diagnosed. The patient was taken to the operating theatre for surgery of several fractures of both upper and lower extremities. This was followed by control X-rays including both anterior-posterior and lateral views of the right hip. This demonstrated that the right hip was now dislocated. The dislocation was reduced. CT showed a larger fracture of the acetabulum, and this was treated with osteosynthesis. Patients with an unstable hip due to trauma, should as a general rule have the hip X-rayed in two planes. It is further suggested that in cases of severely traumatized patients X-ray of the pelvis should be routinely performed.

Accidents, Traffic↗

Rearrangement of human cell homologous chromosome domains in response to ionizing radiation.

Chromosomes are located within the interphase nucleus in regions called domains. Using fluorescence in situ hybridization with whole chromosome paints, a pain of homologous chromosomes can be visualized as two discrete domains and their relative spatial location determined. This study examines the effects of an ionizing radiation exposure on the relative spatial location of chromosome 7 and 21 domains in human skin fibroblasts and lung endothelial cells. The distance between homologous chromosome domains was assessed for each nucleus, before and after exposure to ionizing radiation, using conventional epifluorescence and confocal laser scanning microscopy. Results from conventional microscopy indicated that homologous chromosome domains were re-positioned closer to each other within interphase nuclei after exposure to radiation. Analysis of three-dimensional data obtained from confocal microscopy confirmed these results. In control cells, and in cells examined immediately after irradiation, 66.2% +/- 2.1% of the homologous chromosome 21 domains within endothelial cell nuclei were located greater than 4.0 microns apart (33.8% +/- 1.9% were less than 4.0 microns apart). However, when cells were examined 2 h after a 4.0 Gy gamma-ray exposure, only 30.5% +/- 2.1% of the homologous chromosome domains were greater than 4.0 microns apart (69.5% +/- 2.1% were less than 4.0 microns apart). Similar results were obtained for chromosomes 7 and 21 in skin fibroblast nuclei. The results indicate that homologous chromosome domains rearranged and became closer together within the interphase nuclei in response to ionizing radiation. The exact mechanism of this response is unknown, but it may be related to DNA repair processes. It is speculated that chromosome domains are re-positioned to permit repair of radiation-induced DNA damage.

Cell Nucleus↗

Response of mouse spermatogonial stem cells to X-ray induction of heritable reciprocal translocations.

Although heritable translocations are an important endpoint for the assessment of genetic risk from radiation, there has been a serious information gap with regard to their induction in spermatogonial stem cells, the most important cell stage in males for risk considerations. This led to uncertainty in estimating the magnitude of risk per unit exposure. Further, the relationship between the frequency of reciprocal exchanges scored by cytological analysis of the exposed male's meiocytes and the frequency of those transmitted to first-generation offspring needed to be re-examined. In order to fill in these gaps, two radiation studies, i.e., dose response and dose fractionation, were conducted on spermatogonial stem cells in which heritable and cytologically detected translocations were scored. The present data are by far the most extensive, to date, for heritable translocation induction in spermatogonial stem cells. The linearity of the rising portion of the dose-effect curve and the additivity of effects observed in the fractionation study allow a direct estimation of the number of transmissible translocations expected per unit exposure. Thus, the expected increase in heritable translocations per rad of acute X-rays is 3.89 X 10(-5) per gamete. The data also show a lack of consistency between cytologically and genetically scored translocations.

Animals↗

Syntheses and reactivity studies of solvated dirhenium acetonitrile complexes.

Fully and partially solvated triply-bonded [Re2]4+ complexes have been synthesized and their X-ray structures are described. A fully solvated dirhenium salt with BArf [tetrakis(3,5-bis(trifluoromethyl)phenyl)borate] as the counter anion [Re2(CH3CN)10][BArf]4 () has been characterized. The solubility of the complex in CH2Cl2 and THF in addition to CH3CN offers the possibility of improved reactivity. The structure of [Re2(micro-O)(CH3CN)10][BF4]4 () that possesses a linear [Re(III)-O-Re(III)]4+ unit is reported. Protonation reactions of cis-Re2Cl2(dppm)2(O2CCH3)2 and trans-Re2Cl4(dppm)2 with HBF4.Et2O in acetonitrile afforded cis and trans [Re2(dppm)2(CH3CN)6][BF4]4 ( and ), respectively. Prolonging the reaction time, however, does not lead to fully solvated complex [Re2(CH3CN)10][BF4]4. The neutral nitrogen donor ligands pynp (2-(2-pyridyl)-1,8-naphthyridine) and tznp (2-(2-thiazolyl)-1,8-naphthyridine) react readily with [Re2(CH3CN)10][BF4]4 to provide trans-[Re2(pynp)2(CH3CN)4][BF4]4 and trans-[Re2(tznp)2(CH3CN)4][BF4]4. The X-ray structures trans-[Re2(pynp)2(CH3CN)4][BF4]4 () and trans-[Re2(tznp)2(CH3CN)4][BF4]3[PF6] () have been determined.

Journal Article↗

Stabilization of the proximal ulnar stump in the Sauvé-Kapandji procedure by using the extensor carpi ulnaris tendon: long-term follow-up studies.

PURPOSE: The Sauvé-Kapandji procedure is considered a useful treatment option for distal radioulnar disorders. Postoperative instability of the proximal ulnar stump and radioulnar convergence, however, may be symptomatic. We modified the Sauvé-Kapandji procedure by stabilizing the proximal ulnar stump with a half-slip of the extensor carpi ulnaris tendon. We previously reported on 13 patients with this procedure at an average follow-up period of 35 months; the patients had satisfactory clinical results and improved stability of the proximal ulnar stump as shown by x-ray examination. In this article we address the question of whether those clinical and radiographic results noted at an average follow-up period of 35 months after surgery were maintained at later follow-up examinations. METHODS: We re-examined 12 of the 13 original patients and compared their initial follow-up results with their current results after an average follow-up period of 95 months. RESULTS: The results of this series after 95 months of follow-up evaluation were similar to the results at 35 months. CONCLUSIONS: The results presented in this article suggest that the clinical radiographic results at the 35-month follow-up examination were maintained in the long-term 95-month follow-up evaluation despite the finding that the hole in the proximal ulnar stump had broken in 3 wrists at follow-up examination. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level IV.

Adult↗

Chloroplast NADP-malate dehydrogenase: structural basis of light-dependent regulation of activity by thiol oxidation and reduction.

BACKGROUND: NADP-dependent malate dehydrogenase (EC 1.1.1.82) is a light-activated chloroplast enzyme that functions in the C4 pathway of photosynthesis. The light regulation is believed to be mediated in vivo by thioredoxin-catalyzed reduction and re-oxidation of cystine residues. The rates of reversible activation and inactivation of the enzyme are strongly influenced by the coenzyme substrates that seem to ultimately determine the steady-state extent of activation in vivo. RESULTS: The X-ray structure of the inactive, oxidized enzyme was determined at 2.8 A resolution. The core structure is homologous to AND-dependent malate dehydrogenases. Two surface-exposed and thioredoxin-accessible disulfide bonds are present, one in the N-terminal extension and the other in the C-terminal extension. The C-terminal peptide of the inactive, oxidized enzyme is constrained by its disulfide bond to fold into the active site over NADP+, hydrogen bonding to the catalytic His225 as well as obstructing access of the C4 acid substrate. Two loops flanking the active site, termed the Arg2 and Trp loops, that contain the C4 acid substrate binding residues are prevented from closing by the C-terminal extension. CONCLUSIONS: The structure explains the role of the C-terminal extension in inhibiting activity. The negative C terminus will interact more strongly with the positively charged nicotinamide of NADP+ than NADPH, explaining why the coenzyme-binding affinities of the enzyme differ so markedly from those of all other homologous alpha-hydroxy acid dehydrogenases. NADP+ may also slow dissociation of the C terminus upon reduction, providing a mechanism for the inhibition of activation by NADP+ but not NADPH.

Amino Acid Sequence↗

Mitral valve re-replacement for impaired bioprosthesis after 19 years in a patient undergoing steroid treatment.

A 59-year-old man underwent closed mitral commissurotomy for mitral stenosis at the age of 19 years, and mitral valve replacement (MVR) with a Hancock standard bioprosthesis and tricuspid annuloplasty at the age of 40 years. Two years after the second operation, the patient developed human T-lymphotropic virus type-1 infection, manifesting as myelopathy/tropical spastic paraparesis, and has required steroid therapy for 17 years. He was well for 18 years after the MVR, but has recently developed severe congestive heart failure, orthopnea and enlarged liver. Doppler echocardiography showed severe transvalvular regurgitation of the prosthesis and tricuspid valve. The patient underwent re-MVR with a 27 mm St. Jude Medical prosthesis, and tricuspid annuloplasty. The surgery was well tolerated, without any significant infectious complication. Some tears and perforations were found in the leaflets of the explanted bioprosthesis, but soft X-ray analysis showed minimal calcification. Mild changes and longer durability of the bioprosthesis may be related to the long-term use of steroid therapy.

Adrenal Cortex Hormones↗

[Problems of recurrence and reoperations in discogenic lumboischiadic syndromes. 1].

During the period between Feb. 1 1982 and Dec. 31 1989 at the Neurosurgical Clinic in Kosice 2346 patients were operated (813 women and 1533 men) on account of discogenic lumboischiadic syndrome. Because of true relapses 79 patients were reoperated (29 women, 50 men), i.e., 3.37% of 2346 patients. These formed the investigated group. The youngest patient was 18 years old, the oldest 60 years, the mean age was 38.5 years. Check-up examinations, X-ray material and mathematical evaluation revealed that even marked deviations from the ideal weight according to Broca, balneotherapy, regular physical training and localization of the damaged disc did not influence the development of a true relapse which called for re-operation. The latter were significantly more frequent in subjects engaged in excessively hard physical work and those who developed a complication during the first operation.

Adolescent↗

[Early and late prognosis in acute myocardial infarct. A retrospective study in patients admitted to the coronary care unit in the past 10 years].

The prognostic evaluation of the patient with an acute myocardial infarction is one of the most interesting unanswered problems. This is both because of its complexity and its implications in terms of secondary prevention. Several clinical studies have emphasized the reliability of the prognostic evaluation based on data collected during the first 24 hours. We therefore evaluated the prognostic relevance of 26 variables measured in the coronary care unit in 1914 patients admitted to our Unit as a result of acute myocardial infarction during the past 10 years. Twenty-four patients were lost to follow-up so that the evaluation refers to 1,890 patients, 1,506 of whom are males aged between 22 and 99 years (mean 58.1) and 384 are females aged between 29 and 88 years (mean 67.1); thus there is a greater prevalence of males. The sex-related difference in the age distribution is statistically significant. In-hospital mortality was analyzed using univariate and multivariate statistical methods (chi-squared test, multiple logistic regression analysis). The prognostic relevance of the considered variables in relation to the survival was analysed using the logrank test and using Cox's model. The variables associated with a greater risk of in-hospital death were found to be: age, presence of diabetes, anterior location of the infarct, arterial hypotension at admission, Killip class III and IV and the presence of ventricular tachyarrhithmias. In contrast, smokers had a lower in-hospital death risk. As to mortality during the follow-up, there was an association with age, female sex, pre-existent coronary disease, presence of high heart rate on admission, low peripheral tissue perfusion, x-ray documented pulmonary congestion, supraventricular tachiarrhythmias and intraventricular block. In contrast, the presence of obesity was associated with a reduced death risk during the follow-up. During the follow-up the most frequent cause of death was re-infarction, followed by sudden death, death from non-cardiac causes and heart failure.

Adult↗