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Biomedical subjects

R Kessler

Publications and source records attributed to R Kessler.

At least 55 records · Page 3Linked to original sources
PubMed2001

Study of the K(0)(L) --> pi(+)pi(-)gamma Direct Emission Vertex.

We have performed studies of the K(0)(L)-->pi(+)pi(-)gamma direct emission ( DE) and inner Bremsstrahlung ( IB) vertices, based on data collected by KTeV during the 1996 Fermilab fixed target run. We find a(1)/a(2) = -0.737+/-0.034 GeV2 for the DE form-factor parameter in the rho-propagator parametrization, and report on fits of the form factor to linear and quadratic functions as well. We concurrently measure gamma(K(0)(L)-->pi(+)pi(-)gamma,E(*)(gamma)>20 MeV)/gamma(K(0)(L)-->pi(+)pi(-)) = (20.8+/-0.3)x10(-3), and a K(0)(L)-->pi(+)pi(-)gamma DE/(DE+IB) branching ratio of 0.683+/-0.011.

Journal Article↗
PubMed2001

Search for the decay KL --> pi(0)e+e-.

We report on a search for the decay KL-->pi(0)e+e- carried out by the KTeV/E799 experiment at Fermilab. This decay is expected to have a significant CP violating contribution and the measurement of its branching ratio could support the Cabibbo-Kobayashi-Maskawa mechanism for CP violation or could point to new physics. Two events were observed in the 1997 data with an expected background of 1.06+/-0.41 events, and we set an upper limit B(KL-->pi(0)e+e-)<5.1 x 10(-10) at the 90% confidence level.

Journal Article↗
PubMed2001

Nicotine dependence in the United States: prevalence, trends, and smoking persistence.

BACKGROUND: The prevalence of smoking in the United States has been closely monitored. However, little is known about the epidemiology of nicotine dependence. We studied DSM-III-R nicotine dependence in the United States, trends across cohorts, and the role of nicotine dependence in smoking persistence. METHODS: The Tobacco Supplement to the National Comorbidity Survey was administered to a representative subset of 4414 persons aged 15 to 54 years. The World Health Organization's Composite International Diagnostic Interview was used to assess nicotine dependence. RESULTS: Lifetime prevalence of nicotine dependence was 24%, nearly half of those who had ever smoked daily for a month or more. The highest risk for nicotine dependence occurred in the first 16 years after daily smoking began, at which point the rate declined and continued at a slower pace for several years. Nicotine dependence increased the risk of smoking persistence, with an odds ratio (OR) of 2.2 (95% confidence interval [CI], 1.6-3.0). Members of the most recent cohort, who were 15 to 24 years of age at the time of the survey, were the least likely to smoke daily, but those who smoked had the highest risk of dependence: OR for daily smoking in the most recent vs earliest cohort was 0.7 (95% CI, 0.5-0.9), and for dependence among smokers, 7.2 (95% CI, 5.0-10.4). CONCLUSIONS: Despite evidence that nicotine dependence is the leading preventable cause of death and morbidity, it remains a common psychiatric disorder. Smoking cessation and the decline in uptake in recent years varied across subgroups of the population.

Adolescent↗
PubMed2001

One-step purification of recombinant yeast 6-phosphofructo-2-kinase after the identification of contaminants by MALDI-TOF MS.

His-tagged yeast 6-phosphofructo-2-kinase was overexpressed in the yeast strain DFY658 under the control of the Gal1 promoter. Here we describe a simple and fast purification protocol for the recombinant enzyme under native conditions using a HiTrap affinity column loaded with CuSO(4). The use of MALDI-TOF MS after in-gel-digestion enabled us to identify a critical contamination of the end product as yeast alcohol dehydrogenase1 (Adh1p). After identification this contaminant could be efficiently removed by carrying out the washing steps at 25 degrees C instead of at 4 degrees C. To reduce the cellular proteolytic activities a low phosphate concentration in the growth medium was applied. This simple modification of the yeast cell growth conditions increased significantly the yield of the recombinant protein.

Alcohol Dehydrogenase↗
PubMed2001

Etoposide phosphate with carboplatin in the treatment of elderly patients with small-cell lung cancer: a phase II study.

BACKGROUND: Although the average age of lung cancer patients is increasing, many elderly patients remain undertreated, mainly because of the fear of higher treatment toxicity in this category of patients. We conducted a study to evaluate the efficacy and tolerability of a combination therapy with carboplatin (C) and etoposide phosphate (EP) in elderly patients with Small-Cell Lung Cancer (SCLC). PATIENTS AND METHODS: Previously untreated patients older than 70 years with stage IIIB/IV SCLC received a combination of EP (100 mg/m2 D1, D2, D3) and C (D1, dose calculated according to the Calvert formula). Response rate, survival and toxicity were assessed. RESULTS: Thirty-eight patients (mean age 76 years, range 70-88 years) received a total of 162 cycles. Eighteen patients (47%) received the six scheduled cycles. Thirty patients were evaluable for efficacy (2 CR and 20 PR). The median survival was 237 days and the one-year probability of survival was 26%. The most common adverse effect was transient grade 3 or 4 neutropenia, observed during 57% of evaluable cycles, while five episodes of febrile neutropenia also occurred, with one fatal (bacteremia). It is noteworthy that no renal or liver toxicity was observed, and no mucitis was noted. Unfortunately, a relatively high proportion of patients died shortly after the start of the study. Although most deaths seemed unrelated to the treatment, the possibility of its exacerbatory effect on comorbidities, especially cardiovascular, cannot be excluded. CONCLUSION: The two-drug regimen of carboplatin and etoposide phosphate is feasible in most elderly patients with an acceptable toxicity, and the overall results suggest that patients even older than 70 years may benefit from full treatment. Therefore, consideration should be given to offering active treatment to most patients with SCLC, regardless of age but with special attention paid to comorbidities.

Age Factors↗
PubMed2001

Screening for anxiety and depression in early adolescence.

OBJECTIVE: To examine the level of diagnostic and discriminative accuracy of three dimensional rating scales for detecting anxiety and depressive disorders in a school-based survey of 9th grade youths. METHOD: Classroom screening instruments, the Center for Epidemiologic Studies-Depression Scale (CES-D), the Revised Children's Manifest Anxiety Scale (RCMAS), and the Multidimensional Anxiety Scale for Children (MASC) were administered to 632 youths from three sites in 1998. On the basis of rating scale results, samples of high-scoring and non-high-scoring youths were invited to participate in a diagnostic interview conducted within 2 months of the screening sessions. RESULTS: MASC scores were most strongly associated with individual anxiety disorders, particularly among females, whereas the CES-D composite score was associated with a diagnosis of major depression, after controlling for comorbid disorders. The RCMAS was least successful in discriminating anxiety and depression. When receiver operator characteristic curves were examined, diagnostic accuracy was moderate. CONCLUSIONS: The ability of the MASC and CES-D to discriminate within and between categorically defined diagnostic groups has important implications for the accurate identification of youths in need of services.

Adolescent↗
PubMed2001

Outcome of COPD patients with mild daytime hypoxaemia with or without sleep-related oxygen desaturation.

The aim of the present study was to compare the evolution of pulmonary haemodynamics and of arterial blood gases in chronic obstructive pulmonary disease (COPD) patients with mild-to-moderate hypoxaemia, with or without sleep-related oxygen desaturation. COPD patients with daytime arterial oxygen partial pressure in the range 56-69 mmHg were included prospectively. Sleep-related oxygen desaturation was defined as spending > or = 30% of the nocturnal recording time with arterial oxygen saturation <90%. From the 64 patients included, 35 were desaturators (group 1) and 29 were nondesaturators (group 2). At baseline (t0), patients with sleep-related desaturation had a significantly higher daytime (mean +/- SD) arterial carbon dioxide partial pressure (Pa,CO2) (44.9 +/- 4.9 mmHg versus 41.0 +/- 4.1 mmHg, p=0.001) whereas mean pulmonary artery pressure (mPAP) was similar in the two groups. After 2 yrs (t2) of follow-up, 22 desaturators and 14 nondesaturators could be re-evaluated, including pulmonary haemodynamic measurements. None of the nondesaturator patients became desaturators at t2. The difference between the two groups in terms of daytime Pa,CO2 was still present at t2. The mean changes in mPAP from t0 to t2 were similar between the two groups, as were the rates of death or requirement for long-term oxygen therapy (American Thoracic Society criteria) during follow-up of up to 6 yrs. The presence of sleep-related oxygen desaturation is not a transitional state before the worsening of daytime arterial blood gases, but is a characteristic of some chronic obstructive pulmonary disease patients who have a higher daytime arterial carbon dioxide partial pressure. Such isolated nocturnal hypoxaemia or sleep-related worsening of moderate daytime hypoxaemia does not appear to favour the development of pulmonary hypertension, nor to lead to worsening of daytime blood gases.

Adult↗
PubMed2001

The obesity-hypoventilation syndrome revisited: a prospective study of 34 consecutive cases.

STUDY OBJECTIVES: Obesity has many detrimental effects on the respiratory function and may lead to chronic hypoventilation in some patients, an association known as the obesity-hypoventilation syndrome (OHS). In many cases, patients with OHS also have sleep apneas. Hereafter, we describe several features of a cohort (n = 34) of patients with OHS and show the comparisons with a large cohort (n = 220) of patients with obstructive sleep apnea syndrome (OSAS). We compare also OHS patients with a group of patients with the association of OSAS and COPD, also known as "overlap" patients. DESIGN: Descriptive analysis of prospectively collected clinical data. SETTING: Respiratory care unit and sleep laboratory of university hospital. RESULTS: In OHS patients, OSAS was present in most of the cases (23 of 26 patients). However, in three patients, OHS was not associated with OSAS, showing that obesity per se may lead to chronic hypoventilation. As expected by definition, OHS patients had, on average the worst diurnal arterial blood gas measurements, compared to the other groups. For the OHS patients, the mean diurnal PaO(2) was 59 +/- 7 mm Hg, which was significantly different from the PaO(2) of the OSAS patients (75 +/- 10 mm Hg; p = 0,001) but also from the overlap patients (66 +/- 10 mm Hg; p = 0.015). Pulmonary hypertension (ie, mean pulmonary artery pressure > 20 mm Hg) was more frequent in OHS patients than in "pure" OSAS patients (58% vs 9%; p = 0.001). CONCLUSION: Patients with OSAS and chronic respiratory insufficiency had in most cases an associated OHS or COPD. Patients with OHS were older than patients with pure OSAS. They had mild-to-moderate degrees of restrictive ventilatory pattern due to obesity. Severe gas exchange impairment and pulmonary hypertension were quite frequent. The association of OHS and OSAS was the rule. However, in three patients, OHS was not associated with OSAS, suggesting that OHS is an autonomous disease.

Chronic Disease↗
PubMed2001

Daytime somnolence. Basic concepts, assessment tools and clinical applications.

Excessive somnolence is a common symptom, with a prevalence of 10 to 20% in a general population. However, physicians seldom ask their patients about sleep complaints. The internal biological clock drives the balance between sleepiness and alertness, generating circadian rhythms, with "physiological" increases of somnolence, especially at mid-day and before the habitual bed time. Excessive somnolence is a subjective feeling of an imperious need of sleep in unusual time and environmental conditions. Sleep deprivation, sleep fragmentation and to a lesser degree hypoxia are believed to be the main mechanisms leading to excessive somnolence. Excessive somnolence increases the risk of car accidents, deteriorates health status and quality of life and might increase mortality. Excessive somnolence is associated with many diseases such as obstructive sleep apnoea syndrome. Excessive sleepiness can be assessed by visual scales or questionnaires, the best known being the Epworth sleepiness scale. Objective tests in somnolent patients assess the sleep-wake balance disturbances. The most widely used tests are the multiple sleep latency test (MSLT), the maintenance of wakefulness test (MWT) and the Oxford sleep resistance (OSLER) test. These tests measure the time to sleep emergence in different conditions.

Disorders of Excessive Somnolence↗
PubMed2000

Identification of the putative brain tumor antigen BF7/GE2 as the (de)toxifying enzyme microsomal epoxide hydrolase.

Malignant gliomas are the main cause of death from primary brain tumors. Despite surgery, radiation, and chemotherapy, patients have a median survival of less than a few years; therefore, it is clearly imperative to investigate new ways of treatment. The development of new therapeutic strategies for brain tumors is dependent on a better understanding of the differences between normal and tumoral brain cells. Our group had described previously a Mr 48,000 antigen defined by reactivity with two monoclonal antibodies (GE2 and BF7) obtained by immunization of mice with human glioblastoma cells. Here, we describe the identification of the GE2/BF7 antigen as microsomal epoxide hydrolase (mEH), a drug-metabolizing enzyme that is involved both in toxification and detoxification of carcinogens. We initially used immunoaffinity purification using GE2 and BF7 and analyzed the purified proteins by microsequencing. Edman degradation identified 15 amino acids of the NH2-terminal sequence that were 100% identical to mEH. To further confirm the identity of the BF7/GE2 antigen as mEH, we showed that the protein immunopurified with GE2 and BF7 was recognized by an anti-mEH antibody and that in vitro and in vivo synthesized human mEH is recognized by BF7 and GE2 antibodies. Furthermore, anti-mEH antibody recognizes an antigen expressed both in gliomas and reactive astrocytes, as do BF7 and GE2. Finally, we demonstrate that in contrast to what has been reported in rat embryo fibroblasts, p53 does not regulate mEH mRNA expression in glioma cells.

Animals↗
PubMed2000

[Ab interno trabeculectomy with the Nd:YLF picosecond laser].

BACKGROUND: The outcome of glaucoma surgery is limited by scar formation. As an alternative to current techniques, the opening of the trabecular meshwork ab interno may lead to increased outflow. This study examined the Nd:YLF picosecond laser for ab interno ablation of the trabecular meshwork without opening of the eye. PATIENTS AND METHODS: A Nd:YLF picosecond laser was used which allows tissue to be ablated even through fluids. We performed ablation with different spot sizes and energies in postmortem eyes. Afterwards the effect of the laser treatment was examined by electron microscopy. RESULTS: The ablation threshold for the cornea was found to be 20 J/cm2 for a pulse width of 30 ps. At a lower level of energy (10 J/cm2) ablation of the trabecular meshwork was possible. The size of the focus which was limited by the optics of the slit-lamp was about 50 microns. CONCLUSION: These initial results with a Nd:YLF picosecond laser confirm the possibility of ablating tissue in the trabecular meshwork ab interno without the need to open the eye.

Animals↗
PubMed2000

Regional cerebral activation in irritable bowel syndrome and control subjects with painful and nonpainful rectal distention.

BACKGROUND & AIMS: Irritable bowel syndrome (IBS) is characterized by visceral hypersensitivity, possibly related to abnormal brain-gut communication. Positron emission tomography imaging has suggested specific central nervous system (CNS) abnormalities in visceral pain processing in IBS. This study aimed to determine (1) if functional magnetic resonance imaging (fMRI) detects CNS activity during painful and nonpainful visceral stimulation; and (2) if CNS pain centers in IBS respond abnormally. METHODS: fMRI was performed during nonpainful and painful rectal distention in 18 patients with IBS and 16 controls. RESULTS: Rectal stimulation increased the activity of anterior cingulate (33/34), prefrontal (32/34), insular cortices (33/34), and thalamus (32/34) in most subjects. In IBS subjects, but not controls, pain led to greater activation of the anterior cingulate cortex (ACC) than did nonpainful stimuli. IBS patients had a greater number of pixels activated in the ACC and reported greater intensity of pain at 55-mm Hg distention than controls. CONCLUSIONS: IBS patients activate the ACC, a critical CNS pain center, to a greater extent than controls in response to a painful rectal stimulus. Contrary to previous reports, these data suggest heightened pain sensitivity of the brain-gut axis in IBS, with a normal pattern of activation.

Adult↗
PubMed2000

Prognostic implications of a positive bronchial resection margin.

OBJECTIVE: This retrospective study evaluates probability of survival and mode of recurrence in patients with a microscopically positive bronchial resection margin following resection for primary bronchogenic carcinoma, as well as influence of radiotherapy on survival. METHODS: From January 1986 to July 1997, 40 patients had a microscopically positive bronchial resection margin following a macroscopically complete resection (17 lobectomies, three bilobectomies, four sleeve-lobectomies, and 16 pneumonectomies). Tissue diagnosis was squamous cell carcinoma in 32 patients, adenocarcinoma in four, adenosquamous carcinoma in two and neuroendocrine carcinoma in two. Lymph node status was N0 in 14 patients, N1 in 10, and N2 in 16. The bronchial margin contained carcinoma in situ in 20 patients, invasive mucosal carcinoma in five, and peribronchial infiltration in 15. All patients except the three most recent underwent adjuvant radiation therapy. RESULTS: At the conclusion of the study (January 31st, 1999), 30 patients had died: two with post-operative complications, 17 with progressive disease, ten without relation to cancer, and one under undefined circumstances. Six of 10 unrelated deaths were interpreted as respiratory complications of radiotherapy. Recurrent disease appeared in 24 patients (60%). Nineteen had progression of initial disease (47.5%): metastatic spread in 12 (30%), isolated local recurrence in four (10%), and combined local recurrence and metastases in three (7.5%). Five patients developed metachronous cancer, with bronchial location in four (10%) and laryngeal in one (2.5%). 5-year survival (Kaplan-Meier) in 20 patients with carcinoma in situ was 38.7+/-13.7% (median 31 months), but rose to 55.0+/-16. 6% when excluding seven deaths not related to cancer (five of whom were secondary to radiotherapy) (chi(2)=3.080; P=0.0792). Survival in 13 patients classified N0 was 51.3+/-16.3% (median 61 months), and 71.1+/-18.0% following exclusion of unrelated deaths (chi(2)=3. 939; P=0.0472). Adverse prognosis of peribronchial infiltration was correlated to a positive N status (13 N2 and 2 N1), 5-year survival being 20.0+/-10.3% (median: 18 months). CONCLUSIONS: Prognosis of peribronchial infiltration is similar to N2 disease. In situ carcinoma does not influence survival per se. Local control of disease is probably in part due to radiotherapy. However, the high prevalence of unrelated late deaths suggests an adverse impact of radiotherapy on survival.

Adenocarcinoma↗
PubMed2000

Lung cancer following previous extrapulmonary malignancy.

OBJECTIVE: Having demonstrated a poor prognosis of operable lung cancer in patients with previous head and neck malignancies, we intended to evaluate prognosis of lung cancer in patients with a history of extrapulmonary and extracervical malignancies. METHODS: The population of this study included 55 patients; these were 40 males and 15 females, with a mean age 64.4+/-8.6 years. The previous malignancy was considered tobacco-induced in 15 patients (kidney, two; bladder, ten; esophagus, three), hormone-dependant in 18 (breast, six; female genital, eight; prostate, four), and miscellaneous in 22 (leukemia, four; skin, seven; colon, 11). Following complete resection, 25 patients were classified stage I, 13 were stage II, and 17 were stage IIIA. RESULTS: There were two early perioperative deaths (3.6%), and three during the second month owing to cardiovascular complications. At the conclusion of the study (July 1st, 1997), 32 further patients had died (58.2%): 25 had progression of lung cancer, one had progression of previous malignancy, and six were without evidence of disease. Five-year survival (Kaplan-Meier) was estimated 47+/-10.2% in stage I (median 44 months), 30.8+/-15.6% in stage II (median 26 months), and 16. 7+/-9.9% in stage IIIA (median 17 months). When excluding five early perioperative deaths, 5-year survival was 51.1+/-10.6% in stage I (median 93 months), 33.3+/-16.7% in stage II (median 36.5 months), and 19.0+/-11.2% in stage IIIA (median 20.5 months). Comparing the three groups defined according to location of previous malignancy, there was no significant difference neither in stage distribution (chi(2)=1.326; P=0.857), nor in 5-year survival estimates: 38.9+/-12. 9% (median 27 months) after tobacco-induced malignancies, 38.9+/-11. 5% (median 24 months) following hormone-dependant malignancies, and 28.4+/-10.2% (median 28 months) following miscellaneous cancers (chi(2)=0.059; P=0.9707). CONCLUSIONS: In opposition to data collected in patients with previous head and neck cancer, survival estimates according to stage were contained within the universally accepted range no high risk group has been identified. Resection of lung cancer with curative intent is a fair option in patients with previous extrapulmonary malignancy.

Adult↗
PubMed2000

Development of a brief screening instrument: the HANDS.

BACKGROUND: The present study was designed to develop a briefer screening scale of approximately 10 items which maintained the validity of the Zung Self-Rating Depression Scale in a sample similar to that attending National Depression Screening Day (NDSD), as well as a more general audience. METHODS: We first administered 70 items from a variety of existing rating scales to 40 subjects who answered an ad for depressed subjects and 55 who answered an ad for non-depressed subjects, all of whose diagnoses were confirmed by the Structured Clinical Interview for DSM-IV (SCID). Based on the correlation between each item and the diagnostic criterion, we reduced the number of items to 17 which we then administered to another 45 subjects who answered an ad similar to that used for NDSD and also underwent a SCID interview. Based on these results, we arrived at the final 10-item Harvard Department of Psychiatry/NDSD scale (HANDS) with the assistance of the item-response theory. The items are scored for frequency of occurrence of each symptom over the past 2 weeks. Total scores range from 0 to 30. RESULTS: The 10-item scale (HANDS) has good internal consistency and validity: a cutpoint score of 9 or greater gave sensitivity of at least 95% in both studies. Although specificity was lower for all scales in the self-selected population, the HANDS performed at least as well as the 20-item Zung Scale, the 21-item Beck Depression Inventory-II and the 15-item Hopkins Symptom Depression Checklist. CONCLUSION: The 10-item HANDS performs as well as other widely used longer self-report scales and has the advantage of briefer administration time.

Adolescent↗
PubMed2000

Platypnea-orthodeoxia syndrome related to an aortic aneurysm combined with an aneurysm of the atrial septum.

We report the case of a 71-year-old man bearing a severe right-to-left shunt through a patent foramen ovale in the absence of elevated right-sided heart or pulmonary artery pressures. He presented with platypnea-orthodeoxia syndrome, but he had no pulmonary or extracardiac diseases that are known to be associated with this syndrome. Chest radiography showed a bulky aneurysm of the thoracic aorta. A peripheral contrast transesophageal echocardiography demonstrated a large right-to-left shunt through a patent foramen ovale. In addition, the atrial septum was severely deformed by an aneurysm including this patent foramen ovale. We hypothesized that the opening of the foramen ovale was the result of a mechanical deformation of the atrial septum by two contributing factors: the aneurysm of the thoracic aorta and the aneurysm of the septum itself.

Aged↗
PubMed1999

Attenuated expression of the serum responsive T1 gene in ras transformed fibroblasts due to the inhibition of c-fos gene activity.

The T1 gene encodes a protein, which shares homology with the IL-1 receptors. In fibroblasts, T1 is induced by growth factors and in response to the onset of oncogene expression. The c-fos gene is transiently activated in these situations and was shown to be the major mediator of T1 gene induction. In contrast, the sustained expression of a ras oncogene in NIH3T3 cells resulted in the downregulation of basal T1 gene activity and the attenuation of T1 gene induction in response to mitogenic signals. Likewise, the immediate early genes encoding c-Fos, FosB, and Fra-2 are repressed in these cells. T1 gene repression could be overcome by the forced expression of c-fos in ras transformed fibroblasts. Thus, the lack of c-fos gene expression is the likely cause for ras mediated T1 gene repression. Fra-1, in contrast to the other three members of the Fos family, is permanently synthesized in high amounts in ras transformed NIH3T3 fibroblasts. We show that AP-1, which is abundant in these cells throughout the whole cell cycle, consists predominantly of Fra-1/c-Jun and Fra1/JunD heterodimers. We provide evidence that Fra1/c-Jun heterodimers are responsible for the repression of c-fos gene induction following serum stimulation. The introduction of a dominant negative version of c-Jun into ras transformed fibroblasts was able to rescue c-fos gene induction in response to serum stimulation, further demonstrating that AP-1 is indeed involved in c-fos gene repression. We conclude that oncogenic ras mediates the activation of the fra-1 gene which results in elevated AP-1 activity throughout the cell cycle. Fra-1 containing AP-1 complexes repress the c-fos and possibly other immediate early genes thereby preventing the induction of certain delayed early genes such as the T1 gene in response to mitogenic stimulation.

3T3 Cells↗