Search

This paper describes the final incarnation of the Fermilab High Intensity Lab spectrometer which operated for ten years in the Proton West Area of Fermilab in the execution of two experiments (E537 and E705) which studied hadroproduction of high mass dimuon pairs. The version of the spectrometer used in E771 differed from earlier versions of the spectrometer by the addition of a silicon microstrip detector, pad chambers and resistive plate counters. These additions were implemented to give the spectrometer the capability of detection of secondary decay vertices from B --> mu or B --> J/psi --> mu mu decays. As discussed, the spectrometer in a short data taking period was able to address many kinds of physics, other than beauty decays.

A fast first level muon trigger, developed for and used in experiment E771 at Fermilab, for selecting events containing high energy muons, is described. The trigger finds events by matching the hits information received from three planes of Resistive Plate Counters (RPC). The entire process, accomplished within 450 ns, reduces the total interaction rate by a factor of similar to 10(2) for the single muon trigger and a factor of similar to 10(4) for the dimuon trigger. The capability and performances of the trigger system are described.

The migraine-specific triptans have revolutionized the treatment of migraine and are usually the drugs of choice to treat a migraine attack in progress. Different triptans are available in different strengths and formulations including oral tablets, orally disintegrating tablets, nasal sprays and subcutaneous injections. In Europe, sumatriptan is also available as a suppository. Specific differences among the triptans exist as evidenced by different pharmacological profiles includingT½, Tmax, Cmax, AUC, metabolism, drug-drug interaction profiles, amongst other parameters. How or whether these differences translate to clinical efficacy and tolerability differences is not well differentiated. Clinical distinctions among these agents are subtle and proper choice of triptan requires attention to the specific characteristics of each individual patient, knowledge of patient preference, accurate history of the efficacy of previous acute care medications as well as individual features of the drug being considered. Delivery systems may play an important role in the onset of action of triptans. The selection of an acute antimigraine drug for a patient depends upon the stratification of the patient's migraine attack by peak intensity, time to peak intensity, level of associated symptoms such as nausea and vomiting, time to associated symptoms, comorbid diseases, and concomitant treatments that might cause drug-drug interactions. The clinician has in his armamentarium an ever-expanding variety of medications, available in multiple formulations and dosages, with good safety and tolerability profiles. Continued clinical use will yield familiarity with the various triptans, and it should become possible for the interested physician to match individual patient needs with the specific characteristics of a triptan to optimize therapeutic benefit.Os triptanos, drogas anti-migranosas específicas, revolucionaram o tratamento da migrânea e são considerados as drogas de escolha para o tratamento da crise migranosa. Diferentes triptanos são disponíveis em diferentes formulações, incluindo comprimidos, tabletes de dispersão oral, sprays para administração nasal e injeções subcutâneas. Na Europa, sumatriptan também é disponível como supositório. Diferenças específicas entre os triptanos são evidenciadas por seu diferente perfil farmacológico, incluindo T½, Tmax, Cmax, AUC, metabolismo, perfil de interação entre drogas, entre outros parâmetros. Controvérsias existem sobre se, ou como, essas variáveis traduzem-se em eficácia clínica e tolerabilidade. A distinção clínica entre esses agentes é sutil e a escolha adequada de um triptano requer consideração sobre as características específicas de cada paciente, conhecimento da preferência dos mesmos, obtenção de história acurada sobre a eficácia de medicações previamente utilizadas, assim como consideração sobre as características individuais das diversas drogas. A via posológica parece desempenhar importante papel no modo de ação dos triptanos. A seleção de droga antimigranosa adequada para o tratamento da crise migranosa depende da estratificação do ataque de acordo como a intensidade da dor, tempo para que a máxima intensidade da dor seja atingida, sintomas associados, tempo para que os sintomas associados se manifestem, doenças concomitantes e tratamentos adjuvantes que possam causar interações medicamentosas. O clínico dispõe em seu armamentário uma variedade de medicamentos em constante expansão, em múltiplas formulações e dosagens, seguras e com bom perfil de tolerabilidade. O uso continuado dos triptanos perimitirá familiaridade com essa classe de medicação e possibilitará ao clínico a prescrição de drogas com características específicas para atender as necessidades clínicas de diferentes pacientes, de modo a otimizar o benefício terapêutico.

The short-term prospects for Fermilab experiment E771 - devoted to the hadroproduction of beauty - are described as well as the major characteristics of the spectrometer. Expectations for detection and reconstruction of exclusive B decay channels are discussed.

Um número crescente de pacientes vêm sendo submetidos a procedimentos dialíticos em todo o mundo. Cerca de 70% deles apresentam cefaléia. A despeito disso, a cefaléia não é sintoma bem estudado nesse grupo de pacientes. Os objetivos desse estudo são: avaliar possíveis fatores desencadeantes da cefaléia relacionada à hemodiálise e avaliar o tratamento analgésico utilizado nessa situação. Foram estudados prospectivamente 50 pacientes com insuficiência renal crônica seguidos em três serviços de hemodiálise da cidade de Ribeirão Preto, Estado de São Paulo, Brasil, entre janeiro de 1998 e dezembro de 1999. Todos apresentavam cefaléia estritamente relacionada às sessões de hemodiálise. Cefaléia ocorreu principalmente na segunda metade das sessões de hemodiálise (86%). Hipertensão arterial (38%), hipotensão arterial (12%) e alterações no peso corporal durante as sessões de hemodiálise (6%) foram os fatores desencadeantes mais frequentemente identificados. Em 28% dos casos não se identificou qualquer fator. Dipirona foi o analgésico mais utilisado (56%). A despeito de ser tão comum é surpreendentemente escassa a literatura disponível a respeito da associação entre cefaléias e insuficiência renal crônica. Esses pacientes, além de suportarem o fardo de conviver com um procedimento doloroso e monótono, porém necessário para mantê-los vivos, têm ainda que conviver com o impacto adicional das cefaléias na maioria das sessões. A identificação dos possíveis fatores desencadeantes e do tratamento disponível pode contribuir para o nosso conhecimento sobre essa associação, com consequente redução do impacto das cefaléias em portadores de insuficiência renal crônica.A growing number of patients have been undergoing dialysis procedures all around the world. Around 70% of the patients receiving dialysis treatment complain about headaches. In spite of this, headache is not well studied in this group of patients. The aims of this study are: to evaluate possible triggering factors related to hemodialysis headache and to evaluate the analgesic treatments used under this situation. We prospectively studied 50 patients with chronic renal failure attending to three dialysis services from the town of Ribeirão Preto, State of São Paulo, Brazil, from January 1998 to December 1999. All of them presented headaches strictly related to the hemodialysis sessions. Headache occurred mainly in the second half of the hemodialysis (86%). Arterial hypertension (38%), arterial hypotension (12%) and changes in the weight during the hemodialysis sessions (6%) were the most consistently triggering situations. In 28% of the cases no factors were identified. Dipyrone was, by far (56%), the most frequently analgesic used. Despite being so common it noteworthy how scarce are studies in literature concerning headaches in patients with chronic renal failure. These patients, besides having to bear the burden of living with a painful and boring procedure to keep them alive, many of them have the additional burden, to live with a headache in most of the sessions. The identification of possible triggering factors and further evaluations of the treatment might increase our knowledge and contribute to reduce the burden of the headaches in patients with chronic renal failure.

Um número crescente de pacientes vêm sendo submetidos a procedimentos dialíticos em todo o mundo. Cerca de 70% deles apresentam cefaléia. A despeito disso, a cefaléia não é sintoma bem estudado nesse grupo de pacientes. Os objetivos desse estudo são: avaliar possíveis fatores desencadeantes da cefaléia relacionada à hemodiálise e avaliar o tratamento analgésico utilizado nessa situação. Foram estudados prospectivamente 50 pacientes com insuficiência renal crônica seguidos em três serviços de hemodiálise da cidade de Ribeirão Preto, Estado de São Paulo, Brasil, entre janeiro de 1998 e dezembro de 1999. Todos apresentavam cefaléia estritamente relacionada às sessões de hemodiálise. Cefaléia ocorreu principalmente na segunda metade das sessões de hemodiálise (86%). Hipertensão arterial (38%), hipotensão arterial (12%) e alterações no peso corporal durante as sessões de hemodiálise (6%) foram os fatores desencadeantes mais frequentemente identificados. Em 28% dos casos não se identificou qualquer fator. Dipirona foi o analgésico mais utilisado (56%). A despeito de ser tão comum é surpreendentemente escassa a literatura disponível a respeito da associação entre cefaléias e insuficiência renal crônica. Esses pacientes, além de suportarem o fardo de conviver com um procedimento doloroso e monótono, porém necessário para mantê-los vivos, têm ainda que conviver com o impacto adicional das cefaléias na maioria das sessões. A identificação dos possíveis fatores desencadeantes e do tratamento disponível pode contribuir para o nosso conhecimento sobre essa associação, com consequente redução do impacto das cefaléias em portadores de insuficiência renal crônica. A growing number of patients have been undergoing dialysis procedures all around the world. Around 70% of the patients receiving dialysis treatment complain about headaches. In spite of this, headache is not well studied in this group of patients. The aims of this study are: to evaluate possible triggering factors related to hemodialysis headache and to evaluate the analgesic treatments used under this situation. We prospectively studied 50 patients with chronic renal failure attending to three dialysis services from the town of Ribeirão Preto, State of São Paulo, Brazil, from January 1998 to December 1999. All of them presented headaches strictly related to the hemodialysis sessions. Headache occurred mainly in the second half of the hemodialysis (86%). Arterial hypertension (38%), arterial hypotension (12%) and changes in the weight during the hemodialysis sessions (6%) were the most consistently triggering situations. In 28% of the cases no factors were identified. Dipyrone was, by far (56%), the most frequently analgesic used. Despite being so common it noteworthy how scarce are studies in literature concerning headaches in patients with chronic renal failure. These patients, besides having to bear the burden of living with a painful and boring procedure to keep them alive, many of them have the additional burden, to live with a headache in most of the sessions. The identification of possible triggering factors and further evaluations of the treatment might increase our knowledge and contribute to reduce the burden of the headaches in patients with chronic renal failure.

Resume Un traitement endoscopique anterieur peut-il modifier le resultat d'une operation de Heller par laparoscopie ? But de l'etude : Le but de cette etude retrospective etait d'evaluer les resultats symptomatiques et objectifs chez les patients traites par une operation de Heller laporoscopique apres echec d'un traitement endoscopique en comparaison avec ceux observes chez les patients operes d'emblee. Patients et methode : De novembre 1992 a decembre 1998, 92 patients ayant un mega-œsophage ont ete operes par une myotomie de Heller associee a une fondoplicature selon Dor. Une endoscopie preoperatoire a ete systematiquement realisee. Soixante patients ont ete d'emblee operes et 32 l'ont ete apres echec d'une dilatation pneumatique (n = 22) ou d'une injection de toxine botulique (n = 10). Resultats : La duree operatoire moyenne et l'incidence d'une dysphagie postoperatoire ont ete identiques dans les deux groupes. Une ouverture de la muqueuse a ete observee dans 5 % des cas chez les patients operes d'emblee et dans 12,5 % chez ceux operes secondairement (NS). Les breches muqueuses ont ete plus frequentes au cours des 30 premieres operations (17 % vs 3,2 %, p Conclusion : Il y a seulement une tendance a l'augmentation du risque de complications et de consequences nefastes sans signification statistique chez les patients deja traites par dilatation ou injection de toxine botulique. L'incidence plus elevee de breches muqueuses au cours des 30 premieres operations semble en rapport avec la courbe d'apprentissage.

The cross section for b{bar b} production in 800 GeV/c pN interactions has been measured in Fermilab experiment E771 to be 43{sup +27}{sub {minus}17}(stat){sup +7}{sub {minus}7}(syst) nb per nucleon from the observation of events in which both the b and the {bar b} decay semimuonically or a B decays into a J/{psi} followed by J/{psi}{r_arrow}{mu}{sup +}{mu}{sup {minus}} . {copyright} {ital 1998} {ital The American Physical Society}

We present the x{sub F} and p{sub T} differential cross sections of J/{psi} and {psi}{sup {prime}}, respectively, in the ranges {minus}0.05{lt}x{sub F}{lt}0.25 and p{sub T}{lt}3.5 GeV/c. The data samples are constituted by about 12000 J/{psi} and 200 {psi}{sup {prime}} produced in proton-silicon interactions at 800 GeV/c and decaying into opposite sign muons. The x{sub F} and p{sub T} distributions are compared with recent results from experiments E789 at the same energy and to leading order QCD predictions using the MRS D0 parametrization for the parton structure function. The measured shapes of the differential cross sections, except for the d{sigma}/dx{sub F} at small x{sub F}, agree very well with the prediction, even though their value is quite a bit larger than the prediction. We also present the cos{theta} differential cross section of the J/{psi} which indicates unpolarized production in contrast with color octet models predictions. {copyright} {ital 1997} {ital The American Physical Society}

We have searched for the flavor changing neutral current decay Do + p-l+p”in the dimuon data obtained by the E771 experiment conducted at Fermilab. No evidence is found. A branching ratio of (-1.0 ‘A:,’ f 0.2) x 10v6 is obtained, corresponding to a 90% confidence level upper limit of 3.3 x 10m6. This new upper limit is about three times more sensitive than the best published limit. (Submitted to Physical Review Letters)

We report on the analysis of Charmonium and Bottomium states produced in p-Si interactions at s =38.7 GeV . The data have been collected with the open geometry spectrometer of the E771 Experiment at the FNAL High Intensity Lab. J ψ , ψ′ and γ total cross sections as well as the ratio B(ψ′ → μμ)σ(ψ′) (B( J ψ → μμ)σ( J ψ )) have been measured. Results are compared with theoretical predictions and with results at other energies.

Experiment 705 at Fermi National Accelerator Laboratory has designed, built, and operated a large acceptance, highly segmented electromagnetic shower calorimeter using SF5 lead glass, SCG1-C scintillating glass, and two types of gas-based fine-grained hodoscopes. The calorimeter was used to reconstruct photons and electrons with energies ranging from a few GeV/ c 2 to over 100 GeV/ c 2 in 300 GeV/ c pion and proton interactions on a lithium target at instantaneous interaction rates approaching several MHz. Construction details of the calorimeter are given. The readout electronics, calibration, and algorithms used to reconstruct the positions and energies of showering particles are discussed. Energy resolution, position resolution, and reconstruction efficiency are assessed using both calibration electron beams and electrons and π 0 mesons reconstructed in 300 GeV/ c interactions.

The muon trigger logic of experiment E771 at Fermilab is described, with emphasis on the design and development of the board dedicated to such a trigger. A programmable gate arrays microchip has been implemented on the TRIGA board, to achieve a flexible kind of trigger. The use of a programmable trigger allows to optimize the signal to background ratio according to the working conditions of the muon detector.

The cross section for bb̅ production in 800GeV/c pN interactions has been measured in Fermilab experiment E771 to be 43-17+27(stat)-7+7(syst)nb per nucleon from the observation of events in which both the b and the b̅ decay semimuonically or a B decays into a J/ψ followed by J/ψ→μ+μ-.

We describe the various side effects occurring in dialysis sessions and indicate measures for their prevention and/or treatment. Next, we analyze dialysis headache in terms of incidence, prevalence, criteria for its inclusion in the classification of the International Headache Society, and factors related to its triggering, ie, bradykinin and nitric oxide (NO), which have increased plasma levels during dialysis. This permits a critical analysis in comparison with NO donor headache in terms of the pathophysiologic mechanisms that mediate the triggering of both conditions. A similarity is particularly detected in terms of the role of NO as the last link in the chain of events that precedes the onset of headache, which is preceded by a latency period of 3 to 4 hours, much longer than the few seconds needed to inactivate NO. A hypothesis is raised to explain this phenomenon, opening new perspectives for the study of the pathophysiology of headaches, including primary headaches.

We have searched for the flavor changing neutral current decay D-0 --> mu(+)mu(-) in the dimuon data obtained by the E771 experiment conducted at Fermilab. No evidence is found. A 90% confidence level upper limit of 4.2 x 10(-6) is obtained for the branching ratio. This new upper limit is about two times lower than the best published result.

A fast first level muon trigger, developed for and used in experiment E771 at Fermilab, for selecting events containing high energy muons, is described. The trigger finds events by matching the hits information received from three planes of resistive plate counters. The entire process, accomplished within 450 ns, reduces the total interaction rate by a factor of similar to 10(2) for the single muon trigger and a factor of similar to 10(4) for the dimuon trigger. The trigger logic is programmable, and it allows for an optimization of the signal to background ratio. The capability and performances of the trigger system are also described.

A silicon strip detector (SSD) system for use in very high rate experiments has been operated in Experiment E771 (Cox, 1989) at the Fermi National Accelerator laboratory. The detector electronics were designed (Swoboda, 1990; Bowden, 1990; Zimmerman, 1989; Christian, 1991) to meet the specific needs of Fermilab experiment E771 using ASIC chip sets where commercial circuits were not suitable. The electronics for the SSD were designed to operate at rates up to 60 Mhz and were operated at interaction rates up to 10(7) interaction/sec (beam rates of 2 x 10(8) proton/sec). In addition to being very fast, the detector for the 1991 run was very compact with 10000 channels of active detector in a volume of 5cm x 5cm x 10cm. An expansion of the system to 16000 channels is planned for the next Fermilab fixed target run. The strip pitch ranged from 25 mum in the center of the detector near the target to 100 mum pitch at the most downstream, outer edges of the detector. The readout is a latch design with pipelined readout and appears to have single strip efficiencies of approximately 75% even in the presence of a high radiation dose (approximately 10(14) protons/CM 2) and high leakage currents(approximately 1 nA/strip). The detector and associated amplifier electronics has presently been operated at 17-degrees-C and is designed to operate as low as 8-degrees-C.

SUMMARY The treatment of Barrett's esophagus is still controversial. Actually, the only method to prevent the development to cancer is endoscopic surveillance, which ensures good results in terms of long-term survival. An ideal treatment capable of destroying columnar metaplasia, followed by squamous epithelium regeneration could potentially result in a decrease of the incidence of adenocarcinoma. Recently most ablative techniques were used, such as photodynamic therapy, ablation therapy with Nd-YAG laser or argon plasma coagulation and endoscopic mucosal resection. We started a prospective study in January 1998, enrolling 94 patients affected by Barrett's esophagus and candidates for antireflux repair in order to assess the effectiveness and the results of endoscopic coagulation with argon plasma combined with surgery in the treatment of uncomplicated Barrett's esophagus. All patients underwent endoscopic treatment with argon plasma; we observed complete response in 68 patients (72.34%), 27 of them (39.7%) underwent antireflux surgery and the other 41 continued medical therapy. Post-operatively 19 patients (70%) underwent regular surveillance endoscopies and in two cases metaplasia recurred. The final objective of these combined treatments should be the complete eradication of metaplastic mucosa. Our experience was that argon plasma coagulation combined with antireflux surgery or proton pump inhibitor therapy gave satisfactory results, even if follow-up is too short to evaluate the potential evolution of metaplasia to cancer. For this reason, we recommend that this technique should be done only in specialized centres and that these patients continue their endoscopic surveillance program.

The migraine-specific triptans have revolutionized the treatment of migraine and are usually the drugs of choice to treat a migraine attack in progress. Different triptans are available in different strengths and formulations including oral tablets, orally disintegrating tablets, nasal sprays and subcutaneous injections. In Europe, sumatriptan is also available as a suppository. Specific differences among the triptans exist as evidenced by different pharmacological profiles includingT½, Tmax, Cmax, AUC, metabolism, drug-drug interaction profiles, amongst other parameters. How or whether these differences translate to clinical efficacy and tolerability differences is not well differentiated. Clinical distinctions among these agents are subtle and proper choice of triptan requires attention to the specific characteristics of each individual patient, knowledge of patient preference, accurate history of the efficacy of previous acute care medications as well as individual features of the drug being considered. Delivery systems may play an important role in the onset of action of triptans. The selection of an acute antimigraine drug for a patient depends upon the stratification of the patient's migraine attack by peak intensity, time to peak intensity, level of associated symptoms such as nausea and vomiting, time to associated symptoms, comorbid diseases, and concomitant treatments that might cause drug-drug interactions. The clinician has in his armamentarium an ever-expanding variety of medications, available in multiple formulations and dosages, with good safety and tolerability profiles. Continued clinical use will yield familiarity with the various triptans, and it should become possible for the interested physician to match individual patient needs with the specific characteristics of a triptan to optimize therapeutic benefit. Os triptanos, drogas anti-migranosas específicas, revolucionaram o tratamento da migrânea e são considerados as drogas de escolha para o tratamento da crise migranosa. Diferentes triptanos são disponíveis em diferentes formulações, incluindo comprimidos, tabletes de dispersão oral, sprays para administração nasal e injeções subcutâneas. Na Europa, sumatriptan também é disponível como supositório. Diferenças específicas entre os triptanos são evidenciadas por seu diferente perfil farmacológico, incluindo T½, Tmax, Cmax, AUC, metabolismo, perfil de interação entre drogas, entre outros parâmetros. Controvérsias existem sobre se, ou como, essas variáveis traduzem-se em eficácia clínica e tolerabilidade. A distinção clínica entre esses agentes é sutil e a escolha adequada de um triptano requer consideração sobre as características específicas de cada paciente, conhecimento da preferência dos mesmos, obtenção de história acurada sobre a eficácia de medicações previamente utilizadas, assim como consideração sobre as características individuais das diversas drogas. A via posológica parece desempenhar importante papel no modo de ação dos triptanos. A seleção de droga antimigranosa adequada para o tratamento da crise migranosa depende da estratificação do ataque de acordo como a intensidade da dor, tempo para que a máxima intensidade da dor seja atingida, sintomas associados, tempo para que os sintomas associados se manifestem, doenças concomitantes e tratamentos adjuvantes que possam causar interações medicamentosas. O clínico dispõe em seu armamentário uma variedade de medicamentos em constante expansão, em múltiplas formulações e dosagens, seguras e com bom perfil de tolerabilidade. O uso continuado dos triptanos perimitirá familiaridade com essa classe de medicação e possibilitará ao clínico a prescrição de drogas com características específicas para atender as necessidades clínicas de diferentes pacientes, de modo a otimizar o benefício terapêutico.

The International Headache Society (IHS) criteria for headache related to haemo-dialysis consider that the headaches must begin during haemodialysis and terminate within 24 h. Twenty-eight patients whose headaches started by the time they entered the dialysis programme were prospectively studied. We were not able to classify eight patients that presented the headaches between the sessions. Despite the small number of patients in our study being too low to provide a basis for change in the IHS classification, it serves as an observational report demonstrating possible varieties of headache related to haemodialysis.

Objective.—To determine the prevalence and clinical characteristics of headache in patients undergoing hemodialysis and to compare the prevalence of headache prior to and following the beginning of a hemodialysis program. Background.—About 70% of patients receiving hemodialysis complain of headache. Despite this, headaches have not been well studied in this group of patients. Methods.—We evaluated a series of patients with chronic renal failure who attended 3 hemodialysis services in a Brazilian town from January of 1998 to December of 1999. Patients with headache were prospectively followed and classified according to the International Headache Society criteria. The headaches were also categorized according to their temporal profile relative to hemodialysis. Results.—Headache was reported by 87 (70.7%) of the 123 patients studied. Prior to beginning dialysis, 48% had migraine, 19% had episodic tension-type headache, and 8% had both. Headache related to arterial hypertension was the second most frequent headache diagnosis in these patients (25.4%). Fifty patients (57.5%) experienced headache during the session of hemodialysis. Thirty-four were classified as dialysis headache, 7 were classified as migraine, 7 as episodic tension-type headache, and 2 were unclassified. Twenty-four patients (27.6%) reported dramatic improvement of their headaches after the beginning of the dialysis program. Conclusions.—Headache is common in patients undergoing hemodialysis. Classification of such headaches according to the International Headache society criteria may be difficult.

The rationale for pursuing beauty physics at the SSC in a fixed target configuration is described. The increased beauty production cross section at the SSC, combined with high interaction rate capability of the proposed detector, results in 10 10–11 produced BB events per year. The long decay length of the B hadrons (≌10 cm) allows direct observation of B decays in the high resolution silicon microstrip vertex detector. To optimize the operation of the proposed beauty spectrometer and the SSC, parasitic extraction of attendant or artificially generated large amplitude protons using crystal channeling is proposed and explored. The large sample of fully reconstructed B events allows detailed studies various CP violating decays with requisite statistics to confront the standard model. The CP physics potentials of the proposed experiment is evaluated and compared with alternative approaches, such as asymmetric e + e − B Factories and specialized hadron colliders.

A growing number of patients have been undergoing dialysis procedures all around the world. Around 70% of the patients receiving dialysis treatment complain about headaches. In spite of this, headache is not well studied in this group of patients. The aims of this study are: to evaluate possible triggering factors related to hemodialysis headache and to evaluate the analgesic treatments used under this situation. We prospectively studied 50 patients with chronic renal failure attending to three dialysis services from the town of Ribeirão Preto, State of São Paulo, Brazil, from January 1998 to December 1999. All of them presented headaches strictly related to the hemodialysis sessions. Headache occurred mainly in the second half of the hemodialysis (86%). Arterial hypertension (38%), arterial hypotension (12%) and changes in the weight during the hemodialysis sessions (6%) were the most consistently triggering situations. In 28% of the cases no factors were identified. Dipyrone was, by far (56%), the most frequently analgesic used. Despite being so common it noteworthy how scarce are studies in literature concerning headaches in patients with chronic renal failure. These patients, besides having to bear the burden of living with a painful and boring procedure to keep them alive, many of them have the additional burden, to live with a headache in most of the sessions. The identification of possible triggering factors and further evaluations of the treatment might increase our knowledge and contribute to reduce the burden of the headaches in patients with chronic renal failure.

The readout system developed to handle the signals generated by the resistive plate counter muon detector of Fermilab experiment E771 is described. The results obtained during a test run in the summer of 1990 and concerning one quarter of the total system are reported. They indicate that the RPCs and the readout system are suitable as muon detector for beam intensity up to 2 x 10(6) protons/s.

Aim of this study was to assess symptomatic and objective outcome in patients undergoing laparoscopic Heller myotomy after unsuccessful endoscopic treatment, compared to patients having primary surgery.Between November 1992 and December 1998, 92 patients with esophageal achalasia underwent laparoscopic Heller myotomy and Dor fundoplication. Intraoperative endoscopy was routinely performed. Sixty patients had primary surgery (PS); 32 patients had surgery after unsuccessful pneumatic dilatation (PD) (n = 22), or botulinum toxin (Botox) injection (n = 10).The mean operative time and the incidence of postoperative dysphagia were similar in the two groups. The incidence of intraoperative mucosal tears was 5% in the PS group and 12.5% in the PD/Botox group (P = NS). Mucosal tears occurred more frequently during the first 30 operations (17% vs 3.2%, P0.05). Median follow-up was 28 months (range 4-76). An abnormal esophageal acid exposure was documented in 2 patients in the PS group (7.7%), and in two patients in the PD/Botox group (13.3%) (P = NS). Lower esophageal sphincter pressure significantly decreased in both groups (P0.01). The mean percentage of radionuclide residual activity in the esophagus at 1 and 10 minutes significantly decreased in both groups (P0.01).There is only a trend, although not statistically significant, towards an increased risk of complications and adverse effects in patients previously treated by PD and/or Botox. The higher incidence of mucosal tears during the first 30 operations suggests the effect of the learning curve.

The cross sections for the hadroproduction of the {chi}{sub 1} and {chi}{sub 2} states of charmonium in proton-silicon collisions at {radical}(s)=38.8 GeV have been measured in Fermilab fixed target experiment 771. The {chi} states were observed via their radiative decay to J/{psi}{gamma}, where the photon converted to e{sup +}e{sup -} in the material of the spectrometer. The estimated values for the {chi}{sub 1} and {chi}{sub 2} cross sections for x{sub F}>0 are 263{+-}69(stat){+-}32(syst) and 498{+-}143(stat){+-}67(syst) nb per nucleon, respectively. The resulting {sigma}({chi}{sub 1})/{sigma}({chi}{sub 2}) ratio of 0.53{+-}0.20(stat){+-}0.07(syst), although somewhat larger than most theoretical expectations, can be accommodated by the latest theoretical estimates. (c) 2000 The American Physical Society.

Objective To assess the effectiveness of transoral stapled diverticulum esophagostomy in relieving symptoms and decreasing outflow resistance at the pharyngoesophageal junction in patients with Zenker diverticulum. Design Cohort study. From April 1, 1992, until May 31, 1996, the operation was attempted in 95 patients. The median follow-up was 23 months (range, 13-48 months). Setting Tertiary care university hospital. Patients There were 74 men and 21 women, with a median age of 64 years (age range, 37-92 years). All complained of dysphagia and pharyngo-oral regurgitation, and 18 (20%) suffered from recurrent aspiration pneumonia. The median size of the pouch measured by flexible endoscopy was 4 cm (range, 2.5-8 cm). Intervention The septum between the diverticulum and the esophageal lumen was divided under general anesthesia using a linear endostapler introduced through a Weerda endoscope. In most patients, 2 applications of the endostapler with a modified anvil were used. Operative time averaged 23 minutes. Main Outcome Measures Morbidity, symptom score, patient's satisfaction, videofluorographic barium transit, hypopharyngeal intrabolus pressure, upper esophageal clearance of radioisotope. Results A switch to open surgery was required in 3 patients (3.1%), due to difficult exposure of the common wall in 2 cases and a mucosal tear in the other. No postoperative morbidity or mortality was recorded. Oral feeding was started the following day and the median hospital stay was 3 days (range, 2-8 days). Five patients complained of persistent symptoms; 3 of them underwent another endosurgical operation, 1 underwent laser treatment by means of flexible endoscopy, and 1 eventually required open surgery. All patients are asymptomatic at the latest follow-up visit. Postoperative radiologic studies showed free flow of barium in all patients. Manometry showed a significant reduction of hypopharyngeal intrabolus pressure over preoperative values ( P =.003). Radionuclide studies showed a significant reduction of upper esophageal residual activity at 1 minute compared with preoperative values ( P =.006). Conclusions Endosurgical approach to hypopharyngeal diverticula larger than 2 cm is safe and effective. Symptom relief, elimination of the pouch, and decreased outflow resistance at the pharyngoesophageal junction can be obtained without morbidity and with a short hospital stay.

The aim of this study was to investigate the biochemical basis of biomechanical and morphological alterations of upper esophageal sphincter, which have been reported in patients with Zenker's diverticulum. 4-L-Hydroxyproline (4-Hyp) (collagen), isodesmosine (Ides), and desmosine (Des) (elastin) contents were measured in samples of cricopharyngeal muscle (CPM) and muscularis propria of the esophagus below the CPM. The specimens were collected from seven patients operated for Zenker's diverticulum and eight cadavers, without esophageal and connective tissue disease, 4-Hyp was assayed colorimetrically, Ides and Des by high-performance liquid chromatography. Mean (+/-SEM) values were compared by Mann-Whitney U test. In patients, collagen content was significantly increased, both in CPM and in the muscularis propria of the esophagus below the CPM (P < 0.05). In CPM, Ides to Des and collagen to elastin ratios were significantly higher in patients than in controls (P < 0.05). Both the CPM and the upper muscular cuff of the esophagus appear to be involved in the pathogenesis of Zenker's diverticulum. This finding supports the extension of the myotomy to the muscularis propria of the esophagus below the CPM. The alterated Ides to Des ratio suggests a primary disease of CPM as a cause of Zenker's diverticulum.

Six medium-sized ({approx}1 {times} 2 m{sup 2}) drift chambers with pad and stripe readout have been constructed for and are presently operating in Fermi National Accelerator Laboratory experiment E-771. Each chamber module actually represents a pair of identical planes: two sets of anode wires, two sets of stripes, and two sets of pads. The wire planes are read out separately and represent X measurements in the coordinate system of the experiment. The twin stripe and pad planes are internally paired within the chamber modules; stripe signals represent Y measurements and pad signals combination X and Y measurements. Signals which develop on the stripes and pads are mirror (but inverted) images of what is seen on the wires. In addition to being used in the off-line pattern recognition, pad signals are also used as inputs to an on-line high transverse momentum (pt) trigger processor. While the techniques involved in the design and construction of the chambers are not novel, they may be of interest to experiments contemplating very large area, high rate chambers for future spectrometers.