Coexistence of negatively and positively buckled isomers on n+-doped Si(111) − 2 × 1.

A long-standing puzzle regarding the Si(111) − 2 × 1 surface has been solved. The surface energy gap previously determined by photoemission on heavily n-doped crystals was not compatible with a strongly bound exciton known from other considerations to exist. New low-temperature angle-resolved photoemission and scanning tunneling microscopy data, together with theory, unambiguously reveal that isomers with opposite bucklings and different energy gaps coexist on such surfaces. The subtle energetics between the isomers, dependent on doping, leads to a reconciliation of all previous results.

Body fat in men with prolactinoma.

OBJECTIVE: (a) To evaluate body fat in men with prolactinoma and healthy controls, using whole body dual energy x-ray absorptiometry (DXA), and (b) to correlate DXA results with anthropometry and clinical aspects of male prolactinomas. MATERIAL AND METHODS: A cross-sectional study was performed in two University referral centers. Eleven newly-diagnosed men with prolactinoma and 9 with normal PRL levels due to dopamine agonist treatment were submitted to DXA and blood analysis (PRL, testosterone, dihydrotestosterone, estradiol, and SHBG) by the time of their clinical evaluation. They were compared with 14 control men of similar age and body mass index distribution. RESULTS: Newly-diagnosed men with prolactinoma had higher fat percentage in the arms and the total body, when compared with patients treated with dopamine agonists and controls. The former group also presented higher fat percentage in the legs than the controls. Truncal fat percentage of the newly-diagnosed patients was lower than the dopamine agonist treated group. The 3 groups had similar android and gynoid fat contents. Fat percentage of the 6 sites correlated with PRL, testosterone, and dihydrotestosterone levels. CONCLUSION: Newly-diagnosed men with prolactinomas had higher body fat content. Body fat was linked to disease control, especially to the PRL and androgen levels. Consequently, adequate control of hyperprolactinemia should be pursued in order to reduce the risk of obesity and its metabolic complications in men with prolactinoma.

Diagnosis and management of hyperprolactinemia: results of a Brazilian multicenter study with 1234 patients.

OBJECTIVE: The aim of the study was to evaluate clinical and laboratorial features of 1234 patients with different etiologies of hyperprolactinemia, as well as the response of 388 patients with prolactinomas to dopamine agonists. DESIGN, SETTING, AND PATIENTS: A total of 1234 hyperprolactinemic patients from 10 Brazilian endocrine centers were enrolled in this retrospective study. MAIN OUTCOME MEASURE: PRL measurement, thyroid function tests, and screening for macroprolactin were conducted. RESULTS: Patients were subdivided as follows: 56.2% had prolactinomas, 14.5% drug-induced hyperprolactinemia, 9.3% macroprolactinemia, 6.6% non-functioning pituitary adenomas, 6.3% primary hypothyroidism, 3.6% idiopathic hyperprolactinemia, and 3.2% acromegaly. Clinical manifestations were similar irrespective of the etiology of the hyperprolactinemia. The highest PRL levels were observed in patients with prolactinomas but there was a great overlap in PRL values between all groups. However, PRL>500 ng/ml allowed a clear distinction between prolactinomas and the other etiologies. Cabergoline (CAB) was more effective than bromocriptine (BCR) in normalizing PRL levels (81.9% vs 67.1%, p<0.0001) and in inducing significant tumor shrinkage and complete disappearance of tumor mass. Drug resistance was observed in 10% of patients treated with CAB and in 18.4% of those that used BCR (p=0.0006). Side-effects and intolerance were also more common in BCR treated patients. CONCLUSION: Prolactinomas, drug induced hyperprolactinemia, and macroprolactinemia were the 3 most common causes of hyperprolactinemia. Although PRL levels could not reliably define the etiology of hyperprolactinemia, PRL values >500 ng/ml were exclusively seen in patients with prolactinomas. CAB was significantly more effective than BCR in terms of prolactin normalization, tumor shrinkage, and tolerability.

Ca(2+)/nicotinamide adenine dinucleotide phosphate-dependent H(2)O(2) generation is inhibited by iodide in human thyroids.

A calcium and NAD(P)H-dependent H(2)O(2)-generating activity has been studied in paranodular thyroid tissues from four patients with cold thyroid nodules and from nine diffuse toxic goiters. H(2)O(2) generation was detected both in the particulate (P 3,000 g) and in the microsomal (P 100,000 g) fractions of paranodular tissue surrounding cold thyroid nodules (PN), with the same biochemical properties described for NADPH oxidase found in porcine and human thyroids. In PN tissues, the particulate NADPH oxidase activity (224 +/- 38 nmol H(2)O(2) x h(-1) x mg(-1) protein) was similar to that described for the porcine thyroid enzyme. However, no NADPH oxidase activity was detectable in the particulate fractions from eight diffuse toxic goiter patients treated with iodine before surgery; all but one also received propylthiouracil or methimazole in the preoperative period. Thyroid cytochrome c reductase (diffuse toxic goiters = 438 +/- 104 nmol NADP(+) x h(-1) x mg(-1) protein; PN = 78 +/- 10 nmol NADP(+) x h(-1) x mg(-1) protein) and thyroperoxidase (diffuse toxic goiters = 621 +/- 179 U x g(-1) protein; PN = 232 +/- 121 U x g(-1) protein) activities were unaffected by iodide. Thus, the human NADPH oxidase seems to be inhibited by iodinated compounds in vivo and probably is an enzyme involved in the Wolff-Chaikoff effect. Our findings reinforce the hypothesis that thyroid NADPH oxidase is responsible for the production of H(2)O(2) necessary for thyroid hormone biosynthesis.

Attributable risks for kidney cancer in northern Italy.

The percent population attributable risk (AR) for kidney cancer was estimated in relation to smoking habits, beta-carotene intake, history of cystitis and family history of kidney cancer, using data from a case-control study conducted between 1985 and 1989 in Milan, northern Italy. The data comprised 133 histologically confirmed cases of incident kidney cancer and 392 controls, admitted to hospital for a wide range of acute, non-neoplastic, non-smoking-related diseases. On the basis of multivariate odds ratios (ORs), smoking habits accounted for about 26% of cases, a low beta-carotene intake for 18%, a history of cystitis for 7%, and a family history of kidney cancer in first-degree relatives for 3% of cases. Ever smoking and low beta-carotene intake combined explained 38% of all kidney cancers, and the combination of these two factors plus a history of cystitis and a family history of kidney cancer explained 45% of the incidence of the disease. Thus, even if available, dietary information was limited and the AR estimates were based on somewhat arbitrary assumptions. A considerable proportion of kidney cancers could be avoided simply by eliminating smoking and increasing consumption of fruit and vegetables in this Italian population. This would mean that about 1,500 kidney cancer deaths every year in the whole of Italy could be avoided.

Does placebo help establish equivalence in trials of new antidepressants?

Clinical trials of new antidepressants usually compare a new drug to a reference antidepressant and to a placebo. The placebo is intended to validate the trial in the case of a no-difference outcome, i.e., it helps in assessing equivalence. The aim of the present paper is to test whether placebo has indeed helped establish equivalence of effect in comparative trials of new antidepressants. We carried out an example of sample size determination first in a trial to show a difference between the new and control drug, and second in a trial to assess equivalence between two competing drugs. Finally, we retrospectively calculated the maximum difference accepted as equivalence of effect in published trials of new antidepressants. Assuming a response rate to antidepressants of 70%, 294 subjects for each treatment group are needed to show a 10% difference between two antidepressant drugs and more than 1,300 to assess equivalence at a 5% level of delta, the maximum difference acceptable as equivalence of effect. The level of delta in published trials of new antidepressants ranges between 12 and 43%, suggesting they cannot claim to demonstrate equivalence of effect. Therefore, the presence of a placebo arm for comparison didn't help establish whether both drugs really worked the same way. Comparative trials of new antidepressants should adopt a two-arm design, a suitable number of patients and a high standard in the experimental design in order to minimise possible control-event rate variation.

Bidialysis: a new technique.

An increase in solute removal, a shorter dialysis session, the patient's well being and the reduction of global costs are the principal aims of the new hemodialysis methods. The simultaneous use of two hemodialyzers in hemodialysis has been experimented by other researchers. Our technique involves the use of two cuprophan hemodialyzers in sequence (double filter system: DFS), each one connected separately to fresh dialysate. Fifteen symptomatic large patients were treated with DFS and the results were compared to conventional hemodialysis (CHD). After the first hemodialyzer, modification of pH and electrolytes occurred in the plasma composition. In the second hemodialyzer, urea depuration occurred without further significant changes in hydroelectrolytic or acid-basic plasma patterns. The Kt/V increased from 1.10 to 1.29 (18%). The authors conclude that in DFS there was an advantage in urea clearance, osmolarity stability and reduction of side effects.

[Ultrastructure of HeLa cells chromosomes by freeze-etching and shadow casting techniques (author's transl]. / Ultrastruttura di cromosomi di cellule HeLa con la tecnica del freeze-etching e delle repliche ombrate

HeLa cells in metaphase arrest were studied by freeze-etching. The spiral organization of each chromatid appeared clearly, it was, however, impossible to visualize the inner structure of chromosomes. We have also analysed whole metaphase plates by the shadow casting technique; the results obtained do not seem to be useful for diagnostic application.

[An ultrastructural research of pancreatic islets in sodium nitrite poisoned rabbits (author's transl)]. / Ricerca sull'ultrastruttura delle isole pancreatiche in conigli sottoposti ad intossicazione subacuta di sodio nitrito

Following a biochemical and histological study, the pathogenic effects of the sodium nitrite were investigated by the electron microscope. The vasodilator effect of the nitrite causes in the islets edema and dilatation of the sinusoids. We suppose that the increased afflux of blood could favour the secretion of granules till the exhaustion of cells. Moreover, the endoplasmic reticulum becomes more and more homogeneous and finally he loses its characteristic structure. We observed, at last, that the number of pancreatic islets in the poisoned animals is lower than in control animals.

[Rathke's pouch cysts: diagnosis and treatment]. / Cistos de bolsa de Rathke: diagnóstico e tratamento.

We studied retrospectively a series of four patients with Rathke pouch cysts and pointed out to their clinical presentation and treatment. They all occurred with female patients. Predominant symptoms were amenorrhea, headache and visual disorders. We present a revision of the literature concerning various series of Rathke's pouch cysts. We conclude that surgery is the best therapeutical procedure and transsphenoidal approach is the best surgical technique.

[Acromegaly. Diagnostic and therapeutic aspects. Analysis of 18 cases]. / Acromegalia. Aspectos diagnósticos e terapêuticos. Análise de 18 casos.

The authors present a retrospective study of a series of eighteen patients with acromegaly diagnosed, treated and followed by the Endocrinology and Neurosurgery Services of the Hospital Universitário Clementino Fraga Filho of the Federal University of Rio de Janeiro. The average age of the patients was 43.2% years (varying between 15 and 63). Initial complaints were mainly due to somatic alterations in 83.33%; half the cases had manifestations secondary to tumor compression and 53.33% had neuro-ophtalmological alterations. Hypersecretion of growth hormone was demonstrated by basal hormone determinations and dynamic tests. Neuroradiological assessment showed supraselar expansion in 61.11% of cases. Surgical approach was transsphenoidal in all cases. The main objective of this study was to establish diagnostic criteria, discuss the therapeutic conduct and evaluate the results obtained, comparing them with other series of literature.

[Intra-adenomatous pituitary apoplexy]. / Apoplexia hipofisária intradenomatosa.

The authors review the literature on intra-adenomatous pituitary apoplexy with special emphasis on pathophysiology, diagnosis and therapeutic approach. They present five cases, from a series of 86 patients with pituitary tumors, that developed this syndrome. The patients were diagnosed and followed by the Neurosurgery and Endocrinology Services of Hospital Universitario Clementino Fraga Filho, Universidade Federal do Rio de Janeiro. Diagnosis was confirmed by CT-Scan and MRI in all cases, and the treatment of choice was surgical. Conclusions point to the diagnostic difficulties and the urgency of treatment in this clinical setting.

[Complications of pituitary surgery. Analysis of 120 operations at HUCFF-UFRJ]. / Complicações das cirurgias hipofisárias. Análise de 120 cirurgias no HUCFF-UFRJ.

We evaluated 120 pituitary operations performed at Hospital Universitario Clementino Fraga Filho of the Universidade Federal do Rio de Janeiro from 1979 to July 1998 with the aim of analysing the immediate post operative morbidity and mortality. The ages ranged from 15 to 70 years and the clinical diagnoses were: nonsecreting adenomas, 46 (38.34%); acromegaly, 30 (25%); prolactinomas, 29 (24.16%) and Cushing's disease 15 (12.5%). The main endocrine complications were: panhypopituitarism, 16 (13.34%); diabetes insipidus, 15 (12.5%) and adrenocortical insufficiency, 4 (3.34%). Neurological complications: infection, 13 (10.84%); and cerebrospinal fluid leakage, 6 (5%). Two patients died. Our results agree with those of the international literature. We identified a progressive decrease of morbidity and mortality due to surgeon's skill increase and to the uniformity of the clinical team which managed those patients.

[Hormonal dysfunction of nonpituitary lesions from midline and perisellar area]. / Disfunção hormonal em lesões não hipofisárias das regiões selar e periselar.

OBJECTIVE: To analyse clinical and/or laboratorial preoperative hormonal dysfunction, of the nonpituitary intracranial lesions from midline and parasellar area. METHOD: Forty-four patients were evaluated with nonpituitary intracranial lesions, who had images studies (computed tomography or magnetic resonance) and preoperative basal hormonal level; 16 had preoperative hypothalamus-hypophysial function tests (megatests). These patients were divided in two groups. Group I - 34 lesions from midline: 11 craniopharyngiomas, 8 meningiomas, 3 germinomas, 3 tumors of sphenoid sinus, 2 empty sella syndrome, 2 pylocitic astrocytomas, 1 giant aneurysm, 2 mucoceles, 1 III ventricle diverticulum and 1 Rathke's cleft cyst; Group II - 10 lesions from parasellar area: 9 meningiomas and 1 giant aneurysm. RESULTS: In group I, 25/34 (73.5%) patients showed laboratorial hormonal deficit (14 without clinical manifestations) 18/34 (52.9%) hyperprolactinemia (5 with galactorreia) and 8 (53.3%) showed growth hormone deficiency in 15 megatests available in this group; 3 (8.8 %) patients presented central diabetes insipidus (CDI). In group II, 6/10 (60%) patients showed laboratorial hormonal deficit (5 without clinical manifestations), 1 (10%) hyperprolactinemia and 1 growth hormone deficiency (single megatest realized in this group); no patient had preoperative CID. CONCLUSIONS: The presence of nonspecific or poorly valorized clinical manifestations, does not indicate absence of hormonal dysfunction; in this present serie, 19/38 (50%) patients with laboratorial abnormalities, didn't show clinical manifestations. Hormonal dysfunction is frequent in sellar and perisellar nonpituitary lesions, specially involving midline.

[Interferon-beta 1a in relapsing-remitting multiple sclerosis. First report of a Mexican population]. / El interferón-beta la en el tratamiento de la esclerosis múltiple con curso remitente-recurrente. Primera descripción en una población mexicana.

OBJECTIVE: We present the results of a prospective and a longitudinal study of IFN-beta 1a (Rebif) in the treatment of Mexican patients with relapsing-remittin multiple sclerosis (MS). PATIENTS AND METHODS: Twenty five patients were included, all of them fulfilled the diagnostic criteria proposed by Poser, had a clinical evolution of at least 2 years, had 2 to 3 acute attacks of MS in the 12 months preceding study entry and an EDSS < 5.5. Six patients were excluded from the trial, one because of anaphylactic shock, 2 progressed to the chronic form and 3 decided not to continue in the study. These patients were considered as treatment failures and represented 24% of the participants entering the trial. The remaining 19 patients (mean age 29.8, 74% females) completed 2-year follow-up. The mean time of disease duration was 48.8 months. Six million units of IFN-beta 1a were applied thrice weekly, in 8 patients (42%) dosage reduction to 6 millions units twice a week was necessary because of leukopenia or elevation in liver enzymes. RESULTS: In the year before treatment with IFN-beta 1a patients had 2.7 +/- 0.93 acute attacks, after treatment the mean number of acute attacks per year was reduced to 1.94 +/- 2.39 (28.9% reduction). When analyzed by gender there was a 62.9% reduction in acute episodes per year in women and a 27.7% reduction in men (p < 0.05). The most frequent side effects were fatigue, headache, local skin reactions, depressed mood, myalgia, weight variations and somnolence. A few patients developed leukopenia, anemia or elevated liver enzymes. In 31.25% of the patients there was an increase in the number of lesions on MRI, in 31.25% there was a reduction in the number of lesions and in 37.5% no change was noted. CONCLUSION: The best-tolerated dose of IFN-beta 1a was 12 million units/week in women and 18 million units/week in men.

[Cardiac troponin I in chronic hemodialysis. Comparison of methods and results after 3 months]. / Troponina I cardiaca negli emodializzati cronici. Metodi a confronto e risultati a tre mesi.

The laboratory and instrumental markers today in use for the determination of myocardial damage present limitations in dialysis patients due to interference patterns that tend to reduce prognostic evaluation. The aim of this study is to evaluate whether troponin I (cTnI), a recently established marker of myocardial damage, can help to identify, in asymptomatic patients too, minor ischemic lesions that could screen this patient population for future acute cardiac events. In our study of 103 patients undergoing chronic dialysis, instrumental measurements and serum dosages of cTnI were carried out at the onset and after three months, using first and second generation methods. Among the patients who tested positive using the above tests, 4 acute cardiac events were observed. A follow-up of the present study is due in one year's time.

Confinement effects in π-bonded chains at group IV semiconductor (111) surfaces.

The degree of 1D character of surface chains at group IV (111)-2 × 1 reconstructed surfaces is established by surface sensitive optical spectroscopy. Optical experiments on a diamond C(111)-2 × 1 surface show that the absorption peak related to dangling-bond transitions exhibits a marked blueshift upon oxygen exposure of the clean surface. Such behaviour is analogous to that observed on a clean Si(111)-2 × 1 surface. For both surfaces the experimental finding is interpreted in terms of quantum confinement of surface electrons in quasi-one-dimensional π-bonded chains, whose length decreases with oxygen uptake. A different behaviour is observed in Ge(111)-2 × 1, where only a very slight blueshift of the surface-state optical transition is detected upon oxidation. The almost negligible blueshift in Ge(111)-2 × 1 is consistent with a significant coupling between the π-bonded chains resulting in a much less pronounced one-dimensional character of Ge(111)-2 × 1 surface electrons compared to diamond and silicon reconstructed surfaces.

Total arsenic, inorganic arsenic, and other elements concentrations in Italian rice grain varies with origin and type.

Rice is comparatively efficient at assimilating inorganic arsenic (Asi), a class-one, non-threshold carcinogen, into its grain, being the dominant source of this element to mankind. Here it was investigated how the total arsenic (Ast) and Asi content of Italian rice grain sourced from market outlets varied by geographical origin and type. Total Cr, Cd Se, Mg, K, Zn, Ni were also quantified. Ast concentration on a variety basis ranged from means of 0.18 mg kg(-1) to 0.28 mg kg(-1), and from 0.11 mg kg(-1) to 0.28 mg kg(-1) by production region. For Asi concentration, means ranged from 0.08 mg kg(-1) to 0.11 mg kg(-1) by variety and 0.10 mg kg(-1) to 0.06 mg kg(-1) by region. There was significant geographical variation for both Ast and Asi; total Se and Ni concentration; while the total concentration of Zn, Cr, Ni and K were strongly influenced by the type of rice.

Charge transfer between isomer domains on n+-doped Si(111)-2 × 1: energetic stabilization.

Domains of different surface reconstruction-negatively or positively buckled isomers-have been previously observed on highly n-doped Si(111)-2 × 1 surfaces by angle-resolved ultraviolet photoemission spectroscopy and scanning tunneling microscopy/spectroscopy. At low temperature, separate domains of the two isomer types are apparent in the data. It was argued in the previous work that the negative isomers have a lower energy of their empty surface states than the positive isomers, providing a driving force for the formation of the negative isomers. In this work we show that the relative abundance of these two isomers shows considerable variation from sample to sample, and it is argued that the size of the isomer domains is likely to be related to this variation. A model is introduced in which the electrostatic effect of charge transfer between the domains is computed, yielding total energy differences between the two types of isomer. It is found that the transfer of electrons from domains of positive isomers to negative ones leads to an energetic stabilization of the negative isomers. The model predicts a dependence of the isomer populations on doping that is in agreement with most experimental results. Furthermore, it accounts, at least qualitatively, for the marked lineshape variation from sample to sample observed in photoemission spectra.

Effect of inorganic and organic ligands on the sorption/desorption of arsenate on/from Al-Mg and Fe-Mg layered double hydroxides.

This paper describes the sorption of arsenate on Al-Mg and Fe-Mg layered double hydroxides as affected by pH and varying concentrations of inorganic and organic ligands, and the effect of residence time on the desorption of arsenate by ligands. The capacity of ligands to inhibit the fixation of arsenate followed the sequence: nitrate