ABSTRACT
We demonstrate a novel scheme for Raman-pulse and Bragg-pulse atom interferometry based on the 5S-6P blue transitions of ^{87}Rb that provides an increase by a factor â¼2 of the interferometer phase due to accelerations with respect to the commonly used infrared transition at 780 nm. A narrow-linewidth laser system generating more than 1 W of light in the 420-422 nm range was developed for this purpose. Used as a cold-atom gravity gradiometer, our Raman interferometer attains a stability to differential acceleration measurements of 1×10^{-8} g at 1 s and 2×10^{-10} g after 2000 s of integration time. When operated on first-order Bragg transitions, the interferometer shows a stability of 6×10^{-8} g at 1 s, averaging to 1×10^{-9} g after 2000 s of integration time. The instrument sensitivity, currently limited by the noise due to spontaneous emission, can be further improved by increasing the laser power and the detuning from the atomic resonance. The present scheme is attractive for high-precision experiments as, in particular, for the determination of the Newtonian gravitational constant.
ABSTRACT
BACKGROUND: Brazil has a long history of heavy asbestos consumption. However, the number of asbestos-related diseases (ARDs) falls far below the one expected compared with other asbestos consumer countries. AIMS: To examine underreporting of ARDs, that is mesothelioma, asbestosis and pleural plaques, in Brazil's Mortality Information System (SIM). METHODS: Health information systems (HIS) were mapped, datasets retrieved and records of ARD deaths extracted. Records were pair-matched using anonymous linkage to create a single database. ARD-reported cases missing in SIM were considered unreported. The study's period ranged from 2008 to 2014, when every HIS contributed to the ARD records pool. RESULTS: A total of 1298 registered ARD deaths were found, 996 cases of mesothelioma (77%) and 302 (23%) of asbestosis and pleural plaques. SIM was the major single data source of ARD but 335 mesothelioma deaths were missing, an average underreporting of 33%, with no clear time trend. For asbestosis and pleural plaques, underreporting of ARD oscillated from 55% in 2010 to 25% in 2014, a declining trend. ARD underreporting was not associated with sex or age. CONCLUSIONS: One-third of underreported ARD deaths in the universal SIM is unacceptably high and, apparently, it has not been improving substantially over time. After recoveries from multiple databases, the number of cases is still below, which could be expected based on asbestos consumption. Interoperability of multiple information systems could enhance case detection and improve the precision of mortality estimates, which are crucial for surveillance and for evaluation of remedial policies.
Subject(s)
Asbestos , Asbestosis , Lung Neoplasms , Mesothelioma , Pleural Diseases , Pleural Neoplasms , Asbestos/adverse effects , Brazil/epidemiology , Humans , Mesothelioma/etiology , Pleural Diseases/etiology , Pleural Neoplasms/etiologyABSTRACT
Different rehabilitation models for persons diagnosed with disorders of consciousness have been proposed in Europe during the last decade. In Italy, the Ministry of Health has defined a national healthcare model, although, to date, there is a lack of information on how this has been implemented at regional level. The INCARICO project collected information on different regional regulations, analysing ethical aspects and mapping care facilities (numbers of beds and medical units) in eleven regional territories. The researchers found a total of 106 laws; differences emerged both between regions and versus the national model, showing that patients with the same diagnosis may follow different pathways of care. An ongoing cultural shift from a treatment-oriented medical approach towards a care-oriented integrated biopsychosocial approach was found in all the welfare and healthcare systems analysed. Future studies are needed to explore the relationship between healthcare systems and the quality of services provided.
Subject(s)
Health Services Needs and Demand , Persistent Vegetative State/rehabilitation , Health Policy , Hospital Bed Capacity , Humans , Italy , National Health Programs , Regional Health PlanningABSTRACT
BACKGROUND AND AIMS: Diabetic women have a more adverse plasma lipid profile than men. Sex differences in dietary habits may play a role, but are little investigated. The study evaluates the quality of diet, adherence to the nutritional recommendations of the Diabetes and Nutrition Study Group and their relation with plasma lipid in men and women with diabetes. METHODS AND RESULTS: We studied 2573 people, aged 50-75, enrolled in the TOSCA.IT study (clinicaltrials.gov; NCT00700856). Plasma lipids were measured centrally. Diet was assessed with a semi-quantitative food frequency questionnaire. Women had a more adverse plasma lipid profile than men. Women consumed significantly more legumes, vegetables, fruits, eggs, milk, vegetable oils, and added sugar, whereas men consumed more starchy foods, soft drinks and alcoholic beverages. This stands for a higher proportion (%) of energy intake from saturated fat and added sugar (12.0 ± 2.4 vs 11.5 ± 2.5 and 3.4 ± 3.2 vs 2.3 ± 3.2, P < 0.04), and a higher intake of fiber (11.2 ± 2.8 vs 10.4 ± 2.6 g/1000 Kcal/day) in women. Adherence to the recommendations for saturated fat and fiber consumption was associated with significantly lower LDL-cholesterol regardless of sex. Adherence to the recommendations for added sugars was associated with significantly lower triglycerides and higher HDL-cholesterol in men and women. CONCLUSIONS: Men and women with diabetes show significant differences in adherence to nutritional recommendations, but sex differences in plasma lipid profile are unlikely to be explained by nutritional factors. Adherence to the nutritional recommendations is associated with a better plasma lipid profile regardless of sex, thus reinforcing the importance of substituting saturated for unsaturated fat sources, increasing fiber and reducing added sugar intake.
Subject(s)
Choice Behavior , Diabetes Mellitus, Type 2/diet therapy , Diet, Healthy , Feeding Behavior , Lipids/blood , Patient Compliance , Recommended Dietary Allowances , Aged , Biomarkers/blood , Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/diagnosis , Diabetes Mellitus, Type 2/psychology , Female , Food Preferences , Humans , Italy , Male , Middle Aged , Nutrition Assessment , Risk Factors , Sex Factors , Surveys and Questionnaires , Time Factors , Treatment OutcomeABSTRACT
INTRODUCTION: Country-specific information on pediatric GH therapy is available from multi-national studies. METHODS: A total of 1294 children in Spain enrolled in the observational Genetics and Neuroendocrinology of Short-stature International Study (GeNeSIS). Adverse events were assessed in all GH-treated patients (n=1267) and effectiveness in those with GH deficiency (GHD, 78%). RESULTS: Mean age at time of entry to the study was 9.8 years. GH was initiated at a median (Q1-Q3) 0.22 (0.20-0.25) mg/kg/week and administered for 2.8 (1.6-4.4) years. For 262 patients with GHD and 4-year data, mean (95% CI) height velocity was 4.3 (4.1 - 4.6) cm/year at baseline, 9.0 (8.7 to 9.4) cm/year at 1-year, and 5.5 (5.2 to 5.8) cm/year at 4-years. Height standard deviation score (SDS) was -2.48 (-2.58 to -2.38) at baseline and -1.18 (-1.28 to -1.08) at 4 years. Final height SDS minus target height SDS (n=241) was -0.09 (-0.20 to 0.02). In 1143 GH-treated patients with ≥1 year follow-up, 93 (8.1%) reported treatment-emergent adverse events. Serious events were reported for 7 children, with 2 considered GH-related. CONCLUSION: These data confirm the benefit of GH replacement therapy on height gain for the patients in Spain. The safety profile was consistent with that already known for GH therapy.
Subject(s)
Growth Disorders/drug therapy , Human Growth Hormone/therapeutic use , Body Height , Child , Human Growth Hormone/adverse effects , Humans , SpainABSTRACT
BACKGROUND AND AIMS: Apart from late motor nerve dysfunction, factors affecting muscle strength in diabetes are largely unknown. This study was aimed at assessing muscle strength correlates in diabetic subjects encompassing a wide range of peripheral nerve function and various degrees of micro and macrovascular complications. METHODS AND RESULTS: Four-hundred consecutive patients with type 1 and 2 diabetes (aged 46.4 ± 13.9 and 65.8 ± 10.3 years, respectively) from the Study on the Assessment of Determinants of Muscle and Bone Strength Abnormalities in Diabetes (SAMBA) were examined for upper and lower body muscle isometric maximal voluntary contraction by dynamometry. Univariate and multivariate regression analyses were applied to identify strength correlates. Isometric force at both the upper and lower limbs was significantly lower in subjects with than in those without any complication. At univariate analysis, it was strongly associated with age, diabetes duration, physical activity (PA) level, cardio-respiratory fitness, anthropometric parameters, surrogate measures of complications, and parameters of sensory and autonomic, but not motor (except amplitude) neuropathy. Multivariate analysis revealed that upper and lower body strength correlated independently with male gender and, inversely, with age, autonomic neuropathy score (or individual autonomic function abnormalities), and vibration perception threshold, but not sensory-motor neuropathy score. Diabetes duration and PA level were excluded from the model. CONCLUSIONS: Both upper and lower body muscle strength correlate with measures of diabetic complications and particularly with parameters of sensory and especially autonomic nerve function, independently of diabetes duration and PA level, thus suggesting the involvement of mechanisms other than manifest motor nerve impairment.
Subject(s)
Diabetes Complications/diagnosis , Diabetes Mellitus, Type 2/physiopathology , Diabetic Neuropathies/diagnosis , Motor Neuron Disease/diagnosis , Muscle Strength/physiology , Adult , Aged , Diabetes Complications/complications , Diabetes Complications/physiopathology , Diabetes Mellitus, Type 1/complications , Diabetes Mellitus, Type 1/physiopathology , Diabetes Mellitus, Type 1/therapy , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/therapy , Diabetic Neuropathies/physiopathology , Female , Humans , Male , Middle Aged , Motor Activity , Motor Neuron Disease/physiopathology , Multivariate Analysis , Prospective StudiesABSTRACT
AIMS: A new assay, much more rapid and efficient than the existing standardized tests, is introduced for the evaluation of bactericidal activity of chemical disinfectants and antiseptics under simulated practical conditions of use. METHODS AND RESULTS: The bactericidal activity of biocides was quantified using a novel semi-automated assay based on the European Norm (EN) standard suspension tests but determining bacterial cell viability by intracellular adenosine tri-phosphate (ATP) content quantification instead of traditional culture-based microbiological techniques. The new test was validated by comparison to the standard suspension tests EN 1276 and EN 13727. During the validation, the linearity of the ATP detection system, limit of detection, specificity, sensitivity, relative accuracy and precision (repeatability and reproducibility) were determined. CONCLUSIONS: The validation study showed that the new assay evaluates the activity of biocides as well as the EN standard suspension tests, but it allows a large number of test conditions to be efficiently analysed. SIGNIFICANCE AND IMPACT OF THE STUDY: The new test can therefore be applied to accurately establish the lowest active concentration (MBCs) of disinfectants or antiseptics under simulated practical conditions of use and to compare the susceptibility of a large number of strains and conditions via inactivation curves. This is not possible in any reasonably practicable way with the EN standards considering the time and cost required for each determination.
Subject(s)
Adenosine Triphosphate/analysis , Anti-Infective Agents, Local/analysis , Disinfectants/analysis , Luminescent Measurements/methods , Microbiological Techniques/methods , Bacteria/drug effects , Limit of Detection , Microbial Viability , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
There is no consensus on which drugs/techniques/strategies can affect mortality in the perioperative period of cardiac surgery. With the aim of identifying these measures, and suggesting measures for prioritized future investigation we performed the first International Consensus Conference on this topic. The consensus was a continuous international internet-based process with a final meeting on 28 June 2010 in Milan at the Vita-Salute University. Participants included 340 cardiac anesthesiologists, cardiac surgeons, and cardiologists from 65 countries all over the world. A comprehensive literature review was performed to identify topics that subsequently generated position statements for discussion, voting, and ranking. Of the 17 major topics with a documented mortality effect, seven were subsequently excluded after further evaluation due to concerns about clinical applicability and/or study methodology. The following topics are documented as reducing mortality: administration of insulin, levosimendan, volatile anesthetics, statins, chronic ß-blockade, early aspirin therapy, the use of pre-operative intra-aortic balloon counterpulsation, and referral to high-volume centers. The following are documented as increasing mortality: administration of aprotinin and aged red blood cell transfusion. These interventions were classified according to the level of evidence and effect on mortality and a position statement was generated. This International Consensus Conference has identified the non-surgical interventions that merit urgent study to achieve further reductions in mortality after cardiac surgery: insulin, intra-aortic balloon counterpulsation, levosimendan, volatile anesthetics, statins, chronic ß-blockade, early aspirin therapy, and referral to high-volume centers. The use of aprotinin and aged red blood cells may result in increased mortality.
Subject(s)
Cardiac Surgical Procedures/mortality , Critical Care , Anesthesia , HumansABSTRACT
BACKGROUND: There is no consensus on which drugs/techniques/strategies can affect mortality in the perioperative period of cardiac surgery. With the aim of identifying these measures, and suggesting measures for prioritized future investigation we performed the first international consensus conference on this topic. METHODS: The consensus was a continuous international internet-based process with a final meeting on June 28th 2010 in Milan at the Vita-Salute University. Participants included 340 cardiac anesthesiologists, cardiac surgeons and cardiologists from 65 countries all over the world. A comprehensive literature review was performed to identify topics that subsequently generated position statements for discussion, voting and ranking. RESULTS: Of the 17 major topics with a documented mortality effect, seven were subsequently excluded after further evaluation due to concerns about clinical applicability and/or study methodology. The following topics are documented as reducing mortality: administration of insulin, levosimendan, volatile anesthetics, statins, chronic beta-blockade, early aspirin therapy, the use of preoperative intra-aortic balloon counterpulsation and referral to high-volume centers. The following are documented as increasing mortality: administration of aprotinin and aged red blood cell transfusion. These interventions were classified according to the level of evidence and effect on mortality and a position statement was generated. CONCLUSION: This international consensus conference has identified the non-surgical interventions that merit urgent study to achieve further reductions in mortality after cardiac surgery: insulin, intra-aortic balloon counterpulsation, levosimendan, volatile anesthetics, statins, chronic beta-blockade, early aspirin therapy, and referral to high-volume centers. The use of aprotinin and aged red blood cells may result in increased mortality.
ABSTRACT
PRIMARY OBJECTIVE: The evaluation of school and work reintegration of patients following severe brain injury and of the relationship between the most common (early and late) prognostic indicators and reintegration itself. RESEARCH DESIGN: A retrospective study on a population of 353 patients consecutively admitted to an intensive rehabilitation unit (S. Cuore Hospital, Negrar, Italy) from 1991-1999. METHODS AND PROCEDURES: Evaluation of school and work outcome in this population up to December 2001 (follow-up from 2-10 years post-trauma). Data collection was made using the EBIS (European Brain Injury Society) protocol. RESULTS: In December 2001, 53% of those previously working had returned to competitive work; 76.5% of students were continuing with their studies or had progressed into work. There was a significant difference between employed and non-employed groups in terms of GCS, post-traumatic amnesia (PTA), in-patient rehabilitation length of stay (LOS) and GOS at 6 and at 12 months post-injury. CONCLUSIONS: The data confirm the predictive value of the indices used regarding work reintegration in TBI patients. Nevertheless, prolonged and intensive rehabilitation programmes can lead to high re-employment rates in patients whose initial prognosis seemed very poor.
Subject(s)
Brain Injuries/rehabilitation , Adolescent , Adult , Aged , Amnesia/etiology , Brain Injuries/psychology , Child , Child, Preschool , Disability Evaluation , Employment , Female , Glasgow Coma Scale , Humans , Length of Stay/statistics & numerical data , Male , Middle Aged , Prognosis , Psychomotor Performance , Rehabilitation Centers , Retrospective Studies , SchoolsABSTRACT
BACKGROUND: The role of ghrelin in weight control after surgery is not clear. We examined plasma ghrelin and leptin levels in patients with morbid obesity undergoing biliopancreatic diversion (BPD) of Scopinaro. METHODS: 30 adult patients (27 females, 3 males), undergoing elective BPD were recruited from the Hospital Surgery Service. Fasting blood samples for biochemical determinations were drawn before surgery and 1, 3 and 12 months after BPD. Human plasma ghrelin was measured by RIA. RESULTS: During the study period, weight, BMI and serum leptin levels decreased significantly at all sample points compared to preoperative values. Ghrelin plasma levels increased during the study, with statistical significance at 3 months and 1 year after surgery compared with preoperative levels. While leptin changes correlated with changes in BMI, no correlation was found between ghrelin and leptin or BMI changes. CONCLUSION: Plasma ghrelin levels could be decreased in obese patients as a compensatory mechanism to their nutritional state, but our results do not support the postulated beneficial role of ghrelin in the 1-year weight loss after BPD. They rather suggest that weight loss somehow stimulates ghrelin secretion, even in the absence of part of the stomach.
Subject(s)
Biliopancreatic Diversion/methods , Leptin/blood , Obesity, Morbid/surgery , Peptide Hormones/blood , Adult , Analysis of Variance , Biomarkers/blood , Body Mass Index , Cohort Studies , Fasting , Female , Follow-Up Studies , Ghrelin , Humans , Male , Middle Aged , Monitoring, Physiologic/methods , Obesity, Morbid/diagnosis , Postoperative Care , Probability , Radioimmunoassay , Sensitivity and Specificity , Time Factors , Weight LossSubject(s)
Hypothyroidism/etiology , Aged , Aged, 80 and over , Female , Humans , Radiotherapy/adverse effectsABSTRACT
No disponible
Subject(s)
Aged, 80 and over , Adult , Humans , Aged , Female , Radiotherapy , Hypothyroidism , Precursor Cell Lymphoblastic Leukemia-Lymphoma , Chest PainABSTRACT
BACKGROUND: In essential hypertension, the lower limit of autoregulation of coronary flow shifts to higher perfusion and the hypertensive ventricle is at a higher than normal risk of ischemia, and less able to tolerate acute reduction of coronary perfusion pressure. Little is known about pattern of coronary flow in isolated systolic hypertension, a pathologic condition in which the elevated systolic blood pressure is associated with a lower than normal vascular compliance and normal or slightly greater than normal mean arterial pressure and vascular resistance. OBJECTIVE: To evaluate the effects of rapid normalization of blood pressure on coronary blood flow in isolated systolic hypertension. METHODS: We subjected 20 patients with isolated systolic hypertension to intraoperative hemodynamic and transesophageal echocardiographic monitoring during peripheral vascular surgery. Coronary flow velocity integrals and diameters in the left anterior descending coronary artery were evaluated under baseline conditions and after normalization of blood pressure, which occurred spontaneously during anesthesia (10 cases; group 1A) or was induced by infusion of nitrate (10 cases, group 1B). RESULTS: After normalization of systolic blood pressure integrals decreased significantly only for patients in group 1A; percentage changes of diameter were significantly greater for patients in group 1B. Therefore, coronary blood flow after normalization of systolic blood pressure increased for patients in group 1B (by 28+/-25%) and decreased for patients in group 1A (by 30+/-21%). Changes in integrals were inversely related to those in diameter (r= -0.72, P < 0.001); for patients in group 1A changes in coronary perfusion pressure and diameter were related to those of integrals (r= 0.94; P < 0.0005). CONCLUSIONS: In isolated systolic hypertension, despite there being similar changes of the systolic blood pressure, administration of nitrates caused a marked increase of coronary flow through direct effects on coronary circulation, whereas spontaneous normotension was associated with a significant reduction of coronary flow.
Subject(s)
Blood Pressure/drug effects , Coronary Circulation/drug effects , Hypertension/drug therapy , Aged , Anesthetics, Intravenous , Diazepam , Echocardiography , Echocardiography, Transesophageal , Female , Humans , Hypertension/physiopathology , Male , Middle Aged , Nitroglycerin/therapeutic use , Systole/drug effects , Vasodilator Agents/therapeutic useABSTRACT
BACKGROUND AND AIM OF THE STUDY: Mitral valve repair has recently emerged as the treatment of choice in patients presenting with insufficiency due to valve prolapse. The study aims were to evaluate: (i) the clinical presentation in a consecutive series of patients with mitral valve prolapse undergoing surgical repair; (ii) the correlation between pre- and intraoperative echocardiographic features and surgical findings in these patients; and (iii) whether clinical and echocardiographic data may predict surgical outcome. METHODS: Between March 1997 and May 2000, 152 patients (110 men, 42 women; mean age 59+/-13 years) were recruited into the study. All patients had myxomatous mitral valve disease causing severe regurgitation and underwent systematic examination by transesophageal echocardiography (TEE) for clear delineation of the three scallops of the posterior leaflet and juxtaposed segments of the anterior leaflet. RESULTS: In 119 patients (78%) a flail valve was documented by TEE and confirmed on surgical inspection; an anterior leaflet chordal rupture was not visualized by TEE in one case. In 15 cases (10%) there was flail of the anterior leaflet, and in 105 cases (69%) flail of the posterior leaflet. A bileaflet complex prolapse without chordal rupture was found in 32 cases. On the basis of TEE evaluation, mitral valve replacement was performed electively in 10 patients (7%); the other 142 (93%) underwent mitral valve repair. Adequate repair was obtained in 93% of cases; residual mitral regurgitation (eight cases; grade 3+) and mitral stenosis (one case) were documented by intraoperative TEE, and nine patients (6%) underwent valve replacement. CONCLUSION: The majority of patients with myxomatous mitral valve prolapse and severe regurgitation undergoing valve repair have chordal rupture of the posterior mitral leaflet, a condition in which results of valve repair are excellent. TEE provides a powerful means to define the mechanisms of mitral regurgitation and to identify the suitability of patients for valvuloplasty.
Subject(s)
Echocardiography, Transesophageal , Mitral Valve Insufficiency/surgery , Mitral Valve Prolapse/surgery , Adult , Aged , Chordae Tendineae/diagnostic imaging , Chordae Tendineae/surgery , Female , Humans , Male , Middle Aged , Mitral Valve/diagnostic imaging , Mitral Valve/surgery , Mitral Valve Insufficiency/diagnostic imaging , Mitral Valve Prolapse/diagnostic imaging , Monitoring, Intraoperative , Postoperative Complications/diagnostic imaging , Predictive Value of Tests , Prognosis , Rupture, SpontaneousABSTRACT
A male patient suffering for exertional angina was scheduled for coronary bypass. Physical examination was unremarkable except for oropharynx classified as Mallampati II. After anesthetic induction with fentanyl 10 micrograms/kg, thiopental 5 mg/kg and muscle relaxation with succynilcoline 1 mg/kg, the patient was ventilated via a face mask. Laryngoscopy revealed a bulky mass arising from the rigth base of the tongue hiding the epiglottis and all the vocal apparatus (Cormack class 4); a failed intubation caused bleeding. Facial mask ventilation became more difficult therefore, considering the task on managing the airway, a n. 4 laryngeal mask was positioned by the senior anesthetist. Two intubation attempts failed while ventilation via laryngeal mask became more and more difficult. Surgery was therefore cancelled due to inability to airway management. The mass, biopsied by an otolaryngologist, resulted to be a lingual tonsillar hyperthrophy and therefore was not removed. The patients was re-scheduled for cardiac surgery. Maintaining spontaneous breathing during light sedation, with topical anesthesia, this patient was successfully intubated over an Olympus BF P 10 bronchoscope. The patient had an uneventful operation, was regularly extubated and was discharged on the sixth postoperative day free from airway complications. Although we followed only some of the guidelines for the management of the difficult airway: a senior anesthetist was immediately called when an anatomic alteration was evident; progressive difficulty in maintaining the airway prompted the positioning of a LMA, the restoration of the spontaneous breathing and the cancellation of the elective operation had been mandatory when a class 4 Cormack was found at laryngoscopy. This situation requires an alternative approach to intubation or with the retrograde technique or with the aid of a fiberscope both maintaining spontaneous breathing.
Subject(s)
Intubation, Intratracheal , Palatine Tonsil/pathology , Anesthesia , Coronary Artery Bypass , Humans , Hypertrophy , Male , Middle Aged , Palatine Tonsil/diagnostic imaging , Tomography, X-Ray ComputedABSTRACT
Evidence has been accumulating in favour of a role for hepatitis C virus (HCV) in the pathogenesis of human lymphoproliferative disorders. HCV infection has been documented in the majority of patients with essential mixed cryoglobulinaemia type II (MC-II); in patients with HCV infection, B-cell clonal expansion have been detected in peripheral blood and bone marrow, and a high prevalence of B-cell non-Hodgkin's lymphomas has been documented. Liver biopsies in chronic hepatitis C frequently show portal lymphoid infiltrates with features of B follicles, whose clonality has not yet been investigated. This study has analysed the B-cell clonality of portal lymphoid infiltrates from 16 patients with chronic HCV hepatitis. Portal tracts showing obvious lymphoid infiltrates were microdissected from the paraffin-embedded liver tissue sections and the clonality of lymphoid B-cells was tested using a polymerase chain reaction (PCR) approach designed to identify immunoglobulin heavy chain gene (IgH) rearrangements. A successful IgH-PCR analysis was achieved in 35 lymphoid infiltrates from 11 patients (seven with the four without MC-II) and yielded a single band in 21 cases, two bands in ten cases, and three bands in four cases. Comparison of the IgH-PCR amplification bands obtained from the different lymphoid aggregates of the same biopsy revealed that they differed in size. This finding indicates that each aggregate derives from the proliferation of one or a few founder B-cells, which are not related to each other. The results obtained in patients with and without MC-II were similar, suggesting that the presence of B-cell clonal proliferations in liver biopsies is independent of the occurrence of B-cells producing monoclonal IgMk cryoglobulins.
Subject(s)
B-Lymphocytes/immunology , Hepatitis C, Chronic/immunology , Liver/immunology , B-Lymphocytes/pathology , Cell Division , Clone Cells , Cryoglobulinemia/complications , Cryoglobulinemia/immunology , Gene Rearrangement, B-Lymphocyte, Heavy Chain , Hepatitis C, Chronic/complications , Hepatitis C, Chronic/pathology , Humans , Immunoenzyme Techniques , Liver/pathology , Polymerase Chain ReactionABSTRACT
Thioredoxin reduction in chloroplasts is catalyzed by a unique class of disulfide reductases which use a [2Fe-2S]2+/+ ferredoxin as the electron donor and contain an Fe-S cluster as the sole prosthetic group in addition to the active-site disulfide. The nature, properties, and function of the Fe-S cluster in spinach ferredoxin:thioredoxin reductase (FTR) have been investigated by the combination of UV/visible absorption, variable-temperature magnetic circular dichroism (MCD), EPR, and resonance Raman (RR) spectroscopies. The results indicate the presence of an S = 0 [4Fe-4S]2+ cluster with complete cysteinyl-S coordination that cannot be reduced at potentials down to -650 mV, but can be oxidized by ferricyanide to an S = 1/2 [4Fe-4S]3+ state (g = 2.09, 2.04, 2.02). The midpoint potential for the [4Fe-4S]3+/2+ couple is estimated to be +420 mV (versus NHE). These results argue against a role for the cluster in mediating electron transport from ferredoxin (Em = -420 mV) to the active-site disulfide (Em = -230 mV, n = 2). An alternative role for the cluster in stabilizing the one-electron-reduced intermediate is suggested by parallel spectroscopic studies of a modified form of the enzyme in which one of the cysteines of the active-site dithiol has been alkylated with N-ethylmaleimide (NEM). NEM-modified FTR is paramagnetic as prepared and exhibits a slow relaxing, S = 1/2 EPR signal, g = 2.11, 2.00, 1.98, that is observable without significant broadening up to 150 K. While the relaxation properties are characteristic of a radical species, MCD, RR, and absorption studies indicate at least partial cluster oxidation to the [4Fe-4S]3+ state. Dye-mediated EPR redox titrations indicate a midpoint potential of -210 mV for the one-electron reduction to a diamagnetic state. By analogy with the properties of the ferricyanide-oxidized [4Fe-4S] cluster in Azotobacter vinelandii 7Fe ferredoxin [Hu, Z., Jollie, D., Burgess, B. K., Stephens, P. J., & Münck, E. (1994) Biochemistry 33, 14475-14485], the spectroscopic and redox properties of NEM-modified FTR are interpreted in terms of a [4Fe-4S]2+ cluster covalently attached through a cluster sulfide to a cysteine-based thiyl radical formed on one of the active-site thiols. A mechanistic scheme for FTR is proposed with similarities to that established for the well-characterized NAD(P)H-dependent flavin-containing disulfide oxidoreductases, but involving sequential one-electron redox processes with the role of the [4Fe-4S]2+ cluster being to stabilize the thiyl radical formed by the initial one-electron reduction of the active-site disulfide. The results indicate a new biological role for Fe-S clusters involving both the stabilization of a thiyl radical intermediate and cluster site-specific chemistry involving a bridging sulfide.