Measured attenuation correction methods

Accurate attenuation correction is a prerequisite for the determination of exact local radioactivity concentrations in positron emission tomography. Attenuation correction factors range from 4–5 in brain studies to 50–100 in whole body measurements. This report gives an overview of the different methods of determining the attenuation correction factors by transmission measurements using an external positron emitting source. The long-lived generator nuclide⁶⁸Ge/⁶⁸Ga is commonly used for this purpose. The additional patient dose from the transmission source is usually a small fraction of the dose due to the subsequent emission measurement. Ring-shaped transmission sources as well as rotating point or line sources are employed in modern positron tomographs. By masking a rotating line or point source, random and scattered events in the transmission scans can be effectively suppressed. The problems of measured attenuation correction are discussed: transmission/emission mismatch, random and scattered event contamination, counting statistics, transmission/emission scatter compensation, transmission scan after administration of activity to the patient. By using a double masking technique simultaneous emission and transmission scans become feasible.This article was presented at the 1st EEC workshop on accuracy determination in PET, January 19–20th. 1989 Pisa, Italy (COMAC-BME Concerted Project Characterization and Standardization of PET Instrumentation)     

Psychosocial stress and symptoms of menopause: a comparative study of menopause clinic patients and non-patients

In much of the literature to date, the definition of climacteric symptoms has been based largely upon women who present for medical treatment of symptoms. It is already well recognised that patients (of all ages and both sexes) presenting for medical treatment tend to report themselves as suffering from more life stresses and from more neurotic symptoms than people in the general population. Life stress and adequacy of coping may thus be important factors in the incidence of symptomatology at the climacteric, as at any other time of life. This study therefore investigated the proposal that post-menopausal women who present for treatment at menopause clinics suffer from more life stresses and more neurotic symptoms than post-menopausal women in the general pupolation.

It was found that patients did indeed suffer from more psychosocial stress, measured in terms of life events, clinical depression and anxiety scales and a rating scale based on a clinician's judgements of ongoing psychosocial stress, vulnerability and adequacy of coping. Patients also suffered from significantly more symptoms than non-patients, not only psychological, but also hypothalamic and metabolic symptoms. However, the incidence of hot flushes and vaginal atrophy was the same in both groups. The stress/coping rating was the measure which correlated most highly with the psychological symptoms reported by subjects as symptoms of menopause. Life events and clinical stress measures were more consistently related in the non-patient group, indicating possible intervening variables (such as hormone imbalance) in this relationship in the patient group.     

Somatosensory Evoked Potential Changes With a Selective Attention Task

Somatosensory evoked potential (SEP) changes associated with selective attention were investigated. In 16 subjects, SEPs were recorded from five locations while they counted electrical stimuli to one of four randomly stimulated fingers. Sequential SEP events measured included peaks P30 (positivity at 30 msec). P45, N60, P100. N140. P190. N230, P400. Counting was associated with greater P45, P100. P190, N230, and P400 amplitudes; effects were not attributable to eye or tongue activity. Analyses designed to reveal changes associated with two conceptualized “channels” (finger class, hand) showed that the P45, P100, and P190 amplitude increases involved both channels. The P400 effect was limited to the target finger. Channel effects for N60 and N140 amplitudes resulted from decreases localized to the unattended element of one channel, suggesting “inhibition.” Latency effects involved mainly the hand channel; counted hand latencies were shorter for P30, P45, P100 and P190. The findings indicate modifications of both early and late electrocortical events with selective attention, and that changes can be of several kinds. They support the view that attention proceeds in more than one stage.     

Ensemble noise and current relaxation analysis of K+ current in single isolated salivary acinar cells from rat

The K⁺ channel in rat parotid gland acinar cells were investigated by ensemble current noise analysis in single isolated cells employing the giga-seal whole cell current recording mode. Sets of 20–40 identical de- and hyperpolarization voltage steps were applied and the resultant current records were processed by computer to obtain the mean and the variance of the current. The time-course of the mean current could be fitted by the sum of two exponentials, suggesting a 3-state model. The simplest plausible hypothesis is a model with one open and two closed states. Assuming this model, the relationship between the variance (₂) and the mean current (I) could be fitted by the function ₂/I=i–I/N. The estimated single channeli/V-relations were similar to those taken from single channel current recordings, and the size of the population of channels per cell (N) was 76±26 (n=12). The validity of the model was tested by a successful simulation of the time-course of the variance.     

中学生生活事件与抑郁的关系

目的：探讨中学生具体生活事件和抑郁状况的关系。方法：采用青少年生活事件量表和中学生抑郁量表对558名中学生进行问卷调查。结果：除个别生活事件项目外，青少年生活事件量表中的多数项目均与中学生抑郁呈显著正相关；生活事件与抑郁的回归分析表明，学习负担重，受人歧视冷遇，不喜欢上学，家庭经济困难，与同学或好友发生纠纷，升学压力，被盗或丢失东西，考试失败或不理想，受批评或处分，生活习惯明显变化，恋爱不顺利或失恋，被罚款等12类生活事件进入了对抑郁的回归方程，对抑郁的预测作用较大。结论：中学生生活事件与其抑郁存在广泛的正相关关系。12项生活事件对中学生抑郁有较大的预测作用。     

CD8+T-bet+ cells as a predominant biomarker for inclusion body myositis

Background

Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.

Electrical properties of metallic electrodes

The series equivalent resistance R and capacitance C of metal/saline electrode/electrolyte interfaces were measured as a function of frequency (100 Hz–20k Hz) and current density (0·25 to 1000 A m⁻²) for eight typical electrode metals. For each of the metals tested, R decreased and C increased as the current density was increased above a critical value (with the exception of silver and MP35N at frequencies above 1 kHz for which R increased and C decreased slightly). With the exception of copper, the current density linearity limit (for 10 per cent decrease in R or 10 per cent increase in C) increased with increasing frequency and, in most cases, the current density linearity limit for 10 per cent increase in C was slightly less than that for 10 per cent decrease in R. Among the metals tested, copper and aluminium had the lowest current carrying capability and rhodium had the highest current-carrying capability. The current carrying capabilities of 316 SS, platinum, silver and MP35N, were intermediate and similar. With increasing current density, an increase in the electrode/electrolyte capacitance was the most sensitive indicator of the current-carrying linearity limit.     

SARS疫情期间公众心态影响及变化趋势分析

目的：探索重大突发性公共卫生事件对社会公众心理行为的影响，以及在不同阶段中公众心态变化的特点。方法：对SAILS流行期间374人次的心理咨询记录进行分析，依据疫情发展情况，比较各阶段的差异。结果：在咨询者中，女性(59．4％)多于男性(40．6％)；根据疫情变化将咨询记录数据划分为三个阶段，分析发现随着疫情缓和，针对SARS症状的咨询者显著减少，从13．1％降低到1．8％；有关社会生活的咨询者显著增多，从8．7％上升到12．3％；在有关情绪问题的咨询者中，伴有相关症状者显著减少，从23．0％降低到4．5％；不伴相关症状者显著增多，从77．0％上升到95．5％。结论：整个SAILS疫情期问，情绪问题始终占第一位；随SARS疫情缓和，社会公众对于疾病本身的关注减少，而与疫情有关的社会生活问题增多；面对突发性公共卫生事件，及时开通心理咨询热线电话是十分必要的。     

Providing Interdisciplinary Geriatric Team Care: What Does It Really Take?

We concur with Speer and Schneider's arguments (2003 ; this issue) that more psychologists should offer mental health services to older adults and that the primary care system is a good focus of such efforts. Three issues deserve more prominence in their review. First, their argument that older adults are averse to mental health services seems incorrect, given research indicating that older adults prefer psychotherapy to medication for treatment of depression. Second, psychologists working in primary care need to be aware of new Current Procedural Terminology (CPT) codes that allow documentation of psychological work in medical settings. Third, Speer and Schneider allude to interdisciplinary team functioning, but provide little information about models of team care or issues in developing a well-functioning interdisciplinary team; this commentary expands on those topics.