Specimen charging and detection of signal from non-conductors in a cathode lens-equipped scanning electron microscope

This paper concerns the problems connected with the observation of a nonconductive specimen in a scanning electron microscope (SEM) when incident electrons create a surface charge and a corresponding electric field. The special configuration of the cathode lens enables one to control the landing energy of primary electrons via the specimen bias. In the cathode lens, the accelerating electric field at the surface of the specimen combines itself with that of the surface charge in influencing the trajectories of the signal electrons and hence the detected signal level and the possible recapturing of slow secondaries. Recaptured electrons reduce the ultimate positive surface potential, which arises when working below the higher critical energy of electron impact. Computer simulations of electron trajectories were performed for the typical cathode lens configuration and for a model specimen characterized by emission yields similar to those for glass. The simulations brought an extensive set of data about the trajectories of both secondary and backscattered electrons. Furthermore, the data were processed in order to assess the charge balance between the emitted and recaptured electrons as well as the collection efficiency of the detector. The results include values of the ultimate positive surface potential and the detected signal level, both in dependence on the initial energy of the electron impact and the size of the field of view. Finally, the method for the determination of critical energy is reevaluated. This is based on the measurement of the time dependence of the detected signal.

Treatment with cyclosporin A in a patient with Omenn's syndrome

Unless treated with haematopoetic stem cell transplantation, Omenn's syndrome, a rare variant of severe combined immunodeficiency, is associated with a fatal outcome. We describe a male infant showing all the typical features of Omenn's syndrome, who was successfully treated with cyclosporin A to improve clinical condition prior to haematopoetic stem cell transplantation.

Time and economic cost of constipation care in nursing homes

OBJECTIVE

Chronic constipation is a common disorder among residents in long-term care; yet the cost to the nursing home of constipation-related care is not known. The objective of this study was to quantify the nursing staff and supply-related cost of constipation care to nursing homes from the perspective of the nursing home.

DESIGN

Prospective, observational time-and-motion design.

SETTING

Two United States nursing homes.

PARTICIPANTS

A total of 59 nursing home residents with chronic constipation and nursing staff providing constipation care to them.

MEASUREMENTS

Actual time to complete constipation care-related tasks was measured via stopwatch by trained observers, and the number and professional level (eg, staff nurse, CNA) of staff performing each task was recorded. Frequency of constipation care task data was obtained through 60-day retrospective medical chart review for each subject. Nurse wage rate data was obtained from the Nursing Home Salary and Benefits Report, a US-based national source. Resident and nursing home descriptive information was also collected.

RESULTS

The average cost per task occurrence ranged from 0.72 US dollars for enema administration to 1.74 US dollars for oral medication administration. Average nursing staff costs per subject per year were 1577 US dollars for oral medication administration, 215 US dollars for dietary supplement administration, 39 US dollars for constipation assessment, 17 US dollars for suppository administration, and 6 US dollars for enema administration. Based on estimates of frequency of occurrence, the total annual labor and supply cost per long-term care resident with constipation was 2253 US dollars.

CONCLUSION

Nursing staff performance of constipation care-related tasks is time consuming and costly in the long-term care setting.

Utilisation of a sperm quality analyser to evaluate sperm quantity and quality of turkey breeders

1. A relatively new instrument known as a Sperm Quality Analyzer (SQA) offers a rapid assessment of sperm quality and quantity by providing a sperm quality index (SQI). The SQA measures a combination of the intensity of sperm activity and motile concentration by determining the number and amplitude of sperm movements per second in a capillary tube as detected through light beam interference. 2. Because the SQA has not been tested for its potential use in turkeys, the objective was to determine if the SQA could accurately respond to changes in turkey sperm concentration, viability, and motility in semen collected from turkey breeders. 3. The effect of varying concentrations of sperm on SQI values was evaluated by diluting replicate pools of semen from 4 different aged turkey breeder flocks with saline. Results from all 4 flocks showed that semen dilutions greater than 20-fold resulted in a linear decline in SQI values. 4. Additional in vitro analysis evaluated the effects of turkey sperm viability on the SQI under conditions of constant sperm concentration. Incubated, live sperm was mixed in various proportions with thawed, dead sperm to determine changes in viability. Increased proportions of dead sperm caused a decline in the SQI. 5. To assess sperm motility, turkey semen was incubated under either aerobic (motile) or anaerobic (immotile) conditions. Varied amounts of immotile and motile sperm samples were mixed. A linear increase in the SQI was observed as per cent motile sperm increased. 6. These results indicate that the SQA can respond to differences in turkey sperm concentration, viability, and motility using in vitro analyses.

Use of a sperm quality analyser on semen of turkey breeders to monitor storage time effects and age-related changes during a reproductive cycle

1. A relatively new instrument known as a Sperm Quality Analyzer (SQA) offers a rapid assessment of sperm quality and quantity by providing a sperm quality index (SQI). The SQA measures the intensity of sperm activity and motile concentration by determining the number and amplitude of sperm movements per second in a capillary tube as detected through light beam interference. 2. The objectives of the current study were to determine if the SQA could accurately reflect changes in semen quality that occur with prolonged storage of semen and to determine the variation and change in SQI values among individual breeding male turkeys during their semen production cycle. 3. The effect of storage time on SQI values was evaluated by diluting semen with extender and placing the semen on an oscillating shaker at 4 degrees C for 8 h. The SQI values and sperm viability, expressed as % dead sperm, were recorded hourly. The SQI readings declined linearly with increased storage time while % dead sperm increased linearly with increased semen storage. 4. Semen from 220 individual males was analysed monthly for 9 months. Semen diluted 50-fold with saline had lower SQI values during pre- and post-peak phases of production (months 1, 7, 8, and 9 as compared with months 2 to 6 of semen production). The highest SQI values occurred during months 2 to 6. The largest variation in SQI values occurred during months 1 (CV = 26%) and 9 (CV = 31%) with a CV that averaged 16% for the remaining months. 5. Correlation analysis of SQI values for each bird averaged over 9 months with individual male SQIs for each month showed monthly correlation coefficients that ranged from 0.22 to 0.63. 6. These results indicate that the SQA accurately assessed the decline in sperm quality that occurs with prolonged storage of turkey semen and reflected age-related changes in semen quality and quantity that occurred during a semen production cycle of turkey breeders. In addition, the semen quality rank of some turkey breeders in a population changed with age.

Health-related quality of life associated with irritable bowel syndrome: comparison with other chronic diseases

BACKGROUND

Despite the rapidly growing body of literature on health-related quality of life (HRQoL). placing the results in a context that is meaningful to clinicians and patients is often overlooked.

OBJECTIVE

This study sought to quantify the impact of irritable bowel syndrome (IBS) on HRQoL by comparing the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) scores of IBS patients with normative US data and with the scores of patients having other chronic gastrointestinal (GI) and non-GI disorders.

METHODS

Two IBS reference groups were identified from the published literature: a largely untreated community sample of health maintenance organization (HMO) members (N = 92) and a sample of patients with IBS recruited through clinics and in the community (N = 140). SF-36 scores for these groups were compared with published US population norms (N = 2474) and with published scores for 3 other IBS samples (N = 464); a sample with other chronic GI disorders (dyspepsia [N = 126], gastroesophageal reflux disease [GERD] [N = 516]); and samples with other chronic episodic disorders (asthma [N = 375], migraine [N = 303], panic disorder [N = 73], rheumatoid arthritis [N = 693]).

RESULTS

The scores of patients in both IBS reference groups were significantly lower on several SF-36 domains than those of the US normative population (P < 0.003). Scores on several SF-36 scales were also significantly lower in the IBS reference groups compared with the GERD, asthma, and migraine samples (P < 0.003). Depending on the IBS sample used, scores did not differ or were higher compared with those in the sample with dyspepsia. Relative to the samples with panic disorder and rheumatoid arthritis, the IBS groups had significantly higher scores on most SF-36 domains (P < 0.003). Scores for the HMO reference group were generally higher than those for the clinic/community reference group.

CONCLUSIONS

Based on the results of this analysis, IBS is associated with impairment of HRQoL relative to US population norms and to populations with GERD, asthma, or migraine. HRQoL appears to be greater in patients with IBS than in those with panic disorder or rheumatoid arthritis, although the relative symptom severity in these samples was not known.

[Long-term results after surgical tracheotomy and percutaneous dilatation tracheostomy. A comparative retrospective analysis]

Besides surgical tracheostoma for treatment of long-term intubation, percutaneous dilatational tracheostomy (PDT) has become available during the last few years. Long-term results of the PDT are rare in the medical literature. This paper reports a retrospective analysis comparing the results after PDT with those after surgical tracheostomy. The methods include subjective evaluation of both techniques by the patients using a standardized questionnaire. It also includes the objective cosmetic result of the outside scar, as well as endoscopic inspection of the larynx and trachea. The patients own evaluation showed a higher content in the PDT group mainly due to the cosmetic result. The objective data confirmed those results. Patients with surgical tracheostomy had an average scar length of 5 cm (2 inches), compared to 1,2 cm (5 inch) in the PDT group. The endoscopic examination showed minor stenosis of the trachea in both groups that were not functionally relevant. The average stenosis of 14% for the PDT was similar to that observed after surgical tracheostomy which was 19%. The choice of the best technique should be made in close cooperation between head- and neck surgeons and anesthesiologists.

Use of a self-report constipation questionnaire with older adults in long-term care

PURPOSE

The Patient Assessment of Constipation (PAC), a symptom and quality-of-life inventory, was developed among community-dwelling adults under age 65. The purpose of this study was to evaluate the feasibility and validity of an interview format of the PAC for older adults residing in long-term care.

DESIGN AND METHODS

The PAC was administered to 24 nursing home residents aged 65 and older. Cognitive interviewing methods were used to evaluate subjects' understanding and interpretation of PAC items.

RESULTS

The PAC interview required an average of 11 min, 15 s, to complete. Administration modifications for this population included rereading Likert anchor points and the stem question for each item. Subject item interpretation was generally accurate, as was interpretation of Likert anchors.

IMPLICATIONS

The PAC is easily administered and well understood by older adult residents in long-term care and provides a brief method for obtaining constipation-specific symptom and quality-of-life data from this population.

Measuring change in quality of life in response to Helicobacter pylori eradication in peptic ulcer disease: the QOLRAD

This study was designed to determine if a new condition-specific quality of life measure, the Quality Of Life in Reflux And Dyspepsia (QOLRAD), was responsive to clinical change over a four-week period when evaluating peptic ulcer disease patients undergoing Helicobacter pylori (Hp) eradication. A secondary aim was to evaluate QOLRAD's psychometric performance. Hp-positive patients with peptic ulcer disease were recruited from primary care and gastroenterology clinics (N = 155). QOLRAD scores improved significantly (P < 0.0001) and mean total score increase was 1.07 points on a 7-point scale among 111 subjects who responded to Hp eradication. Effect sizes were moderate for responders (0.64) and low for nonresponders (0.36). Score changes below 0.60 were associated with the smallest improvement in patient and physician condition rating; scores above 1.2 were associated with the greatest improvement. The QOLRAD demonstrates reliability and validity. Changes in QOLRAD score can be meaningfully related to clinical changes, aiding evaluation of health-related quality of life in peptic ulcer disease.

The economics of selective serotonin reuptake inhibitors in depression: a critical review

The prevalence of depression and the high costs associated with its treatment have increased interest in pharmacoeconomic evaluations of drug treatment, particularly in the 1990s as the use of selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs) expanded substantially. This review presents results from specific studies representing the key study designs used to address the pharmacoeconomics of SSRI use: retrospective administrative database analyses, clinical decision analysis models, and randomised clinical trials. Methodological considerations in interpreting results are highlighted. In retrospective administrative database analyses, most comparisons have been made between SSRIs and tricyclic antidepressants (TCAs). A few studies have addressed differences between SSRIs. The studies focused on healthcare cost (to payer) and cost-related outcomes (e.g. treatment duration, drug switching). Although SSRIs are generally associated with higher drug acquisition costs than are TCAs, total healthcare costs are at least offset, if not decreased, by reductions in costs associated with use of SSRIs. Although studies from the early 1990s show some advantage for fluoxetine, the results are limited by use of data from shortly after the introduction of paroxetine and sertraline; studies from the mid- 1990s on that compare drugs within the SSRI class show general equivalence in terms of cost. Important methodological advances are occurring in retrospective studies, with selection bias and other design limitations being addressed statistically. Clinical decision analysis models permit flexibility in terms of ability to specify different alternative treatment scenarios and varying durations. Sensitivity analysis aids interpretability, although model inputs are limited by data availability. Results from short term (1 year duration or less) studies comparing SSRIs and TCAs suggest that SSRIs are more cost effective or that there is no difference. Longer term studies (lifetime Markov models) focus more on the impact of maintenance antidepressant therapy and show more mixed results, generally favouring SSRIs over TCAs. The results indicate that the effect of SSRIs is mainly through prevention of relapse. Important assumptions of these models include fewer serious adverse effects and lower treatment discontinuation rates with SSRIs. Naturalistic clinical trials provide greater generalisability than traditional randomised clinical trials. One naturalistic trial found that nearly half of TCA-treated patients switched to another antidepressant within 6 months; only 20% of SSRI-treated patients switched. Cost differences between groups were minimal. These studies indicate few differences in medical costs, depression outcomes and health-related quality of life between TCAs and fluoxetine, although fewer fluoxetine-treated patients switched treatment.

Scanning electron microscopy of nonconductive specimens at critical energies in a cathode lens system

A method for scanning electron microscopy imaging of nonconductive specimens, based on measurement and utilisation of a critical energy, is described in detail together with examples of its application. The critical energy, at which the total electron yield curve crosses the unit level, is estimated on the basis of measurement of the image signal development from the beginning of irradiation. This approach, concentrated onto the detected signal as the only quantity crucial for the given purpose of acquiring a noncharged micrograph, evades consequences of any changes in an irradiated specimen that influence the total electron yield curve and possibly also the critical energy value. Implementation of the automated method, realised using a cathode lens-equipped scanning electron microsope (SEM), enables one to establish a mean rate of charging over the field of view and its dependence on the electron landing energy. This dependence enables one to determine the energy of a minimum damage of the image of the given field of view. Factors influencing reliability and applicability of the method are discussed and examples of noncharged micrographs of specimens from both life and material science fields are presented.

Symptom and health-related quality-of-life measures for use in selected gastrointestinal disease studies: a review and synthesis of the literature

Patient-rated symptom and health-related quality-of-life (HR-QOL) outcomes are important end-points for clinical trials of medical treatments for gastrointestinal (GI) disorders. Based on this review, patient outcomes research is focused on gastroesophageal reflux disease and dyspepsia, with a growing interest in irritable bowel syndrome but little research in gastroparesis. State-of-the-art for patient-rated symptom scales is rudimentary with an abundance of scales and little attention to systematic instrument development or comprehensive psychometric evaluation. Generally, disease-specific HR-QOL measures have been more systematically developed and evaluated psychometrically, but few have been incorporated into clinical trials. More comprehensive outcome assessments are needed to determine the effectiveness of new medical treatments for functional GI disorders. Future clinical trials of GI disorders should combine clinician assessments of outcomes and symptoms with patient-rated symptom and HR-QOL end-points.

Prefrontal, parietal, and temporal cortex networks underlie decision-making in the presence of uncertainty

Decision-making in the presence of uncertainty, i.e., selecting a sequence of responses in an uncertain environment according to a self-generated plan of action, is a complex activity that involves both cognitive and noncognitive processes. Using functional magnetic resonance imaging, the neural substrates of decision-making in the presence of uncertainty are examined. Normal control subjects show a significant activation of a frontoparietal and limbic neural system during a two-choice prediction task relative to a two-choice response task. The most prevalent response strategy during the two-choice prediction task was "win-stay/lose-shift," where subjects will repeat the previous response if it successfully predicted the stimulus and switch to the alternative response otherwise. Increased frequency of responses that are consistent with this strategy is associated with activation in the superior temporal gyrus. In comparison, increased frequency of response inconsistent with win-stay/lose-shift is associated with parietal cortex activation. These results support the hypothesis that subjects use a frontoparietal neural system to establish a contingency based decision-making strategy even in the presence of random reinforcement.

Plant biotechnology. Italian scientists blast GMO restrictions

While plant scientists around the world celebrate the complete sequence of the genome of the mustardlike plant Arabidopsis thaliana (see p. 2054), embattled colleagues in Italy are protesting new rules that bar all field trials involving genetically modified organisms (GMOs). The researchers hope to turn the prevailing tide by bringing their plight to the attention of colleagues around the world and exerting pressure on their government through a petition drive.

Molecular biology. EMBL rescued from the financial brink

Scientists at the European Molecular Biology Laboratory were breathing a sigh of relief last week after the topflight center in Heidelberg, Germany, announced a 25% budget increase for the next 5 years. The boost eases months of uncertainty over how the lab would comply with an order to pay employees back salary and provides a measure of stability to its renowned but embattled European Bioinformatics Institute.