A protein folding intermediate of ribonuclease T1 characterized at high resolution by 1D and 2D real-time NMR spectroscopy

The rate-limiting step during the refolding of S54G/P55N ribonuclease T1 is determined by the slow trans-->cis prolyl isomerisation of Pro39. We investigated the refolding of this variant by one-dimensional (1D) and two-dimensional (2D) real-time NMR spectroscopy, initiated by a tenfold dilution from 6 M guanidine hydrochloride at 10 degreesC. Two intermediates could be resolved with the 1D approach. The minor intermediate, which is only present early during refolding, is largely unfolded. The major intermediate, with an incorrect trans Pro39 peptide bond, is highly structured with 33 amide protons showing native chemical shifts and native NOE patterns. They could be assigned in a real-time 2D-NOESY (nuclear Overhauser enhancement spectroscopy) by using a new assignment strategy to generate positive and negative signal intensities for native and non-native NOE cross-peaks, respectively. Surprisingly, amide protons with non-native environments are located not only close to Tyr38-Pro39, but are spread throughout the entire protein, including the C-terminal part of the alpha-helix, beta-strands 3 and 4 and several loop regions. Native secondary and tertiary structure was found for the major intermediate in the N-terminal beta-strands 1 and 2 and the C terminus (connected by the disulfide bonds), the N-terminal part of the alpha-helix, and the loops between beta-strands 4/5 and 5/6. Implications of these native and non-native structure elements of the intermediate for the refolding of S54G/P55N ribonuclease T1 and for cis/trans isomerizations are discussed.     

Therapeutic controversy: Obesity--a modern-day epidemic

This study reviewed 17 patients (24 great toes) treated by a single surgeon for hallux rigidus with a dorsal-closing wedge osteotomy of the proximal phalanx in conjunction with a moderate cheilectomy. The average age of patients was 47 years (range, 20-69 years). The minimum follow-up was 1 year (range, 1-16 years; median follow-up, 30 months), and all but five patients were studied for 2 years or more. Ninety-six percent of patients affirmed their decision to have surgery if they had to make the choice again. Subjectively, all patients improved. Preoperatively, 67% of the cases had severe pain by American Orthopaedic Foot and Ankle Society criteria. Postoperatively, 58% had no pain and 42% had mild pain. There was 100% union rate of the osteotomy. Seven of 10 women and 1 of 7 men still had some restrictions on footwear options postoperatively. Recovery time from the patients' perspective was 2 to 12 months (average, 5.6 months). Based on the results of this study, the authors suggest that the addition of a dorsal-closing wedge osteotomy of the proximal phalanx increases patient satisfaction, compared with their review of patients treated by cheilectomy alone. The procedure provides good pain relief and has few complications.     

Cisplatin-based neoadjuvant chemotherapy and combined resection for ethmoid sinus adenocarcinoma reaching and/or invading the skull base

OBJECTIVE: To review our experience with cisplatin-based neoadjuvant chemotherapy before en bloc resection via a combined neurosurgical and transfacial approach for ethmoid sinus adenocarcinoma reaching and/or invading the skull base. DESIGN: Case series. SETTING: A tertiary care center and university teaching hospital. PATIENTS: Twenty-two patients with primary untreated ethmoid sinus adenocarcinoma reaching and/or invading the skull base consecutively treated between 1984 and 1992 with cisplatin-based neoadjuvant chemotherapy and combined neurosurgical and transfacial approach. MAIN OUTCOME MEASURES: Statistical analysis of survival, local control, nodal recurrence, distant metastasis, and metachronous second primary tumor incidence based on the Kaplan-Meier actuarial method. Univariate analysis was performed to analyze the relationships between various factors, survival, and local recurrence. Clinical response, histological response, toxic effects of chemotherapy, and postoperative course were also reported. RESULTS: The Kaplan-Meier 3-year survival, local control, nodal recurrence, and distant metastasis estimates were 68.1%, 65.7%, 5.3%, and 10%, respectively. Metachronous second primary tumor was not encountered in our series. Survival was statistically more likely to be reduced in patients with intrasphenoidal tumor extent (P = .04) and local recurrence (P = .01). Local recurrence was statistically more likely in patients with intrasphenoidal tumor extent (P = .002) and no response to cisplatin-based neoadjuvant chemotherapy (P = .03). CONCLUSIONS: The results achieved suggest that cisplatin-based neoadjuvant chemotherapy before combined neurosurgical and transfacial approach should be further investigated for the treatment of ethmoid sinus adenocarcinoma reaching and/or invading the skull base.     

Cholelithiasis and dietary risk factors: an epidemiologic investigation in Vidauban, Southeast France. General Practitioner's Group of Vidauban

Dietary risk factors have been implicated in the development of cholelithiasis. The aim of this study was to determine in a homogeneous French population whether a particular type of diet may be lithogenic. Seventy-six subjects over 30 years of age (26 men, 50 women) with cholelithiasis detected by ultrasound were selected from a population sample of 830 subjects by drawing lots using the polling list. These were matched by 76 control subjects without cholelithiasis randomly selected from the same population. Univariate analysis was significant for a high calorie diet >2500 kcal/day (OR = 3.62, P = 0.0065), a diet rich in carbohydrates with a consumption > or = 55 g/day (OR = 2.98, P = 0.0067), and a diet rich in total lipids (OR = 4.97, P = 0.023) or saturated fatty acids (OR = 3.06, P = 0.0146). An alcohol consumption equivalent to 20-40 g/day was protective (P = 0.018). Multivariate analysis confirmed these results. Our study suggests that a change in dietary habits by limiting excess calories, saturated fats and carbohydrates could reduce the incidence of cholelithiasis.     

An antagonist peptide-EPO receptor complex suggests that receptor dimerization is not sufficient for activation

Dimerization of the erythropoietin (EPO) receptor (EPOR), in the presence of either natural (EPO) or synthetic (EPO-mimetic peptides, EMPs) ligands is the principal extracellular event that leads to receptor activation. The crystal structure of the extracellular domain of EPOR bound to an inactive (antagonist) peptide at 2.7 A resolution has unexpectedly revealed that dimerization still occurs, but the orientation between receptor molecules is altered relative to active (agonist) peptide complexes. Comparison of the biological properties of agonist and antagonist EMPs with EPO suggests that the extracellular domain orientation is tightly coupled to the cytoplasmic signaling events and, hence, provides valuable new insights into the design of synthetic ligands for EPOR and other cytokine receptors.     

Effects of limited mouth opening capacity (trismus) on lung function

In the present study pulmonary function test data were obtained from 15 healthy volunteers and 15 patients with slightly impaired ventilation during both normal and maximally reduced opening of the mouth (trismus, intercuspid position). The aim of the study was to examine the effects of complete trismus on pulmonary function using objective and subjective parameters. In maximally reduced mouth opening, both groups showed an impairment of all subjective and objective pulmonary function test data. In healthy volunteers, the significant changes in the test data (p < 0.05) simulated mild to moderate pulmonary impairment, whereas patients with an already impaired pulmonary function showed a marked deterioration of their initial respiratory condition. The results of the subjective and objective parameters examined indicate that an intercuspid position (trismus) further aggravates pulmonary functional impairments. Complete trismus can be considered a risk factor to pulmonary function in patients using mouth-breathing as primary or supportive mode of respiration.