Multi-scale investigation in the frequency domain of Ar/HMDSO dusty plasma with pulsed injection of HMDSO.

A combination of time-resolved optical emission spectroscopy measurements and collisional-radiative modeling is used to investigate the phenomena occurring over multiple time scales in the frequency domain of a low-pressure, axially-asymmetric capacitively-coupled RF argon plasma with pulsed injection of hexamethyldisiloxane (HMDSO, Si2O(CH3)6). The collisional-radiative model developed here considers the population of argon 1s and all ten 2p levels (in Paschen's notation). The presence of HMDSO in the plasma is accounted for in the model by quenching of the argon 1s states by species generated by plasma processing of HMDSO, including HMDSO-15 (Si2O(CH3)5), acetylene (C2H2) and methane (CH4). Detailed analysis of the relative populations of Ar 2p states reveals cyclic evolutions of the electron temperature, electron density and quenching frequency that are shown to be linked to the kinetics of dust formation in Ar/HMDSO plasmas. Penning ionization of HMDSO and its fragments is found to be an important source of electrons for the plasma maintenance. It is at the origin of the cyclic formation/disappearance of the dust cloud, without attenuation of the phenomenon, as long as the pulsed injection of HMDSO is sustained. The multi-scale approach used in this study further reveals the straightforward relation of the frequency of HMDSO pulsed injection, in particular the HMDSO duty cycle, with the frequency of dust formation/disappearance cycle.

Age-dependency of mycophenolate mofetil dosing in combination with tacrolimus after pediatric renal transplantation.

BACKGROUND: Dosing of mycophenolate mofetil (MMF) must be lower in combination therapy with Tacrolimus (Tac) than with Cyclosporine. One study with mostly adolescent recipients recommended an MMF dose of 250 mg/m2 BID. Because this dose resulted in low area-under-the-curve (AUC) in our infant population, we retrospectively analyzed all available pharmacokinetic (PK) profiles in pediatric renal transplant patients on MMF plus Tac therapy to propose appropriate MMF dosing in pediatric patients of all ages. PATIENTS AND METHODS: Forty-four PK profiles were performed in 27 patients (median age, 11.6 years; range, 1.8-20.7 years). The investigations were performed at a median of 299 days (range, 24-3424) after transplantation. Ten patients were converted to Tac plus MMF, all others received this as primary therapy. For patients with repeated measurements, we calculated the average AUC and doses. We used first-order PK modeling to calculate the doses for a mycophenolic acid (MPA) AUC of 60 ug*h/mL and a Tac AUC of 150 ng*h/mL. RESULTS: The mean Tac dose was 2.6 +/- 1.2 mg/m2/d or 0.086 +/- 0.038 mg/kg/d, resulting in an average AUC of 120.6 +/- 30.4 ng*h/mL. The MMF dose was not normally distributed; the median dose was 549 mg/m2/d (range, 146-1413) and the median MPA AUC was 49.8 ug*h/mL (range, 26.7-156.0). The mean dose for a Tac AUC of 150 ng*h/mL was 3.50 +/- 1.77 mg/m2/d (0.117 +/- 0.058 mg/kg) and was independent of age or time after transplantation. By contrast, we found a negative relationship between the dose per m2 (r2 = 0.29; P = 0.0038) or per kg (r2 = 0.58; P < .0001) required for an MPA AUC of 60 ug*h/mL and patient age. Converted and primary patients behaved identically. The dosing requirement decreased from 500 mg/m2 BID in 2-year-old patients to 250 mg/m2 in adolescents. There was substantial interpatient variability of 44%. CONCLUSIONS: Higher MMF doses are required for young children. Our data suggest a starting dose for infants of 500 mg/m2 BID, with PK monitoring of MPA due to substantial interpatient variability.

Depression and anxiety in oncology: the psychiatrist's perspective.

Depression and anxiety are frequently undiagnosed and untreated in cancer patients, resulting in a significant negative impact on quality of life and disease outcome. Furthermore, although effective therapies for depression and anxiety are available, there have been few clinical trials of pharmacotherapy in cancer patients. This article explores how the diagnosis of depression and anxiety can be improved in cancer patients and reviews current treatment options in the oncology setting. The Hospital Anxiety and Depression Scale, a simple, patient-administered questionnaire, is effective in screening for psychiatric symptoms at an early stage of cancer treatment, particularly if vulnerable individuals can be identified and targeted. Selective serotonin reuptake inhibitors are currently first-choice therapy for depression, and many of the drugs in the class are effective in anxiety disorders. Further studies of these agents in the oncology setting are warranted.

Effects of reduced salinity on survival, growth, reproductive success, and energetics of the euryhaline polychaete Capitella sp. I.

Physiological adjustment to water of reduced salinity requires energy expenditure. In this study we sought to determine the fitness costs associated with such adjustment in the euryhaline polychaete Capitella sp. I, and the extent to which such costs could be explained by increased rates of energy expenditure. In a series of experiments conducted at 20 degrees C, salinity was reduced from 30 per thousand to either 25, 20, 15, 12, or 10 per thousand within 72 h after the larvae had been induced to metamorphose. Juveniles were reared on fine, organic-rich sediment. Over the next 15-30 days, we determined survival, growth, fecundity, and rates of respiration and feeding (via fecal pellet production). Larval salinity tolerance was also determined. Juvenile survival at salinities as low as 12-15 per thousand was comparable to that at 30 per thousand. The lower limit of salinity tolerance was 10-12 per thousand at 20 degrees C for both larvae and juveniles. Juveniles grew significantly more slowly at 12-15 per thousand in six of the seven experiments. Fecundity, however, was generally highest at intermediate salinities of 20-25 per thousand, and comparable at 30 and 15 per thousand. No individuals released embryos at 12 per thousand over the approximately 30-day observation periods in any of the three experiments in which the worms were reared at this low salinity. Reduced growth rates were not explained by differences in rates of respiration at different salinities: at reduced salinity, respiration rates were either statistically equivalent to (P>0.10) or significantly below (P<0.05) those recorded for animals maintained at 30 per thousand. Lower growth rates at lower salinities were best explained by reduced feeding rates. Further studies are required to determine whether digestive efficiency, growth hormone concentrations, or reproductive hormone concentrations are also altered by low salinity in this species.

Sexual abuse in adolescents--data from a psychiatric treatment centre for adolescents.

OBJECTIVES: To determine the prevalence of sexual abuse in a large sample of adolescent psychiatric patients and to compare sexually abused patients with non sexually abused patients, the latter category including non-sexual physically abused and non-abused patients. DESIGN: A retrospective analysis of the patient records at the William Slater Centre for Adolescents, University of Cape Town Medical School/Groote Schuur Hospital. SETTING: The William Slater Centre (WSC) is an outpatient psychiatric treatment centre for adolescents with emotional and behavioural problems. SUBJECTS: Nine hundred and thirty-four adolescent and young adult patients referred to the WSC in Cape Town from February 1990 to April 1997. METHODS: The WSC Assessment form, a semi-structured interview schedule, was used to focus on depressive symptoms, suicidal ideation and parasuicide, eating disorders, substance abuse, psychosexual history, sexual abuse and physical abuse, and Diagnostic and Statistical Manual i.v. diagnosis. RESULTS: One-third of all patients admitted to the centre from February 1990 to April 1997 reported some form of sexual abuse. More sexually abused patients than expected received a diagnosis of depression. On average sexually abused patients scored higher on depression rating scales than non sexually abused patients. Logistic regression showed that the presence of suicidal symptoms and alcohol use are to some extent independently associated with sexual abuse. CONCLUSION: The problem of sexual abuse among South African youth is confirmed by this study. The association between sexual abuse and depression, suicidal symptoms and alcohol use is supported. The country's dwindling psychiatric services therefore face an increasingly challenging future.

Pathways to mental health care among South African adolescents: analysis of referrals to an adolescent psychiatric unit.

Assessment forms of 670 adolescents referred over four years to an adolescent psychiatric unit were analyzed to establish how they entered mental health care. The first part of the study examined referral sources; the second established the appropriateness of referral. Adolescents were referred via a number of pathways, of which school sources, psychiatric services, and social agencies were prominent. Interestingly, 60.7% of the referrals were from persons not trained in mental health care. No significant difference in appropriateness of referral was found between trained and nontrained sources. Thus, the unique referral base of adolescents in need of mental health care must be recognized. Although the majority in this study were not mental health care workers, the findings show that their referrals were clinically appropriate. This suggests that by improving the mental health skills of this sector, the provision of psychiatric care to adolescents could be enhanced.

Psychiatric symptomatology in adolescents with cancer.

Adolescents with cancer need to cope with their disease and treatment while accomplishing the tasks unique to this developmental period. In this pilot study, the prevalence of psychological morbidity among adolescents with cancer was examined. In addition, assessment methods and risk factors were explored. Forty-three recently diagnosed adolescents with cancer completed the Hospital Anxiety and Depression Scale (HADS), the Beck Depression Inventory (BDI), and the Rotterdam Symptom Checklist (RSCL) and underwent a full psychiatric assessment. In the psychiatric interviews, 9% of the sample was diagnosed with a depressive mood disorder. Results suggest that self-report rating scales can be useful assessment instruments if used as complementary tools. Psychosocial assessment of the adolescent with cancer is nevertheless difficult. This appears to be due to an atypical symptomatology pattern and a tendency toward the masking of distress. Case examination of depressed patients suggests that illness and treatment factors may not be primary risk factors for the development of psychological morbidity. External stressors such as poor family support and past sexual abuse, when compounded by illness and treatment factors, may be more relevant.

Depressive disorders in an out-patient oncology setting: prevalence, assessment, and management.

OBJECTIVE: To assess the prevalence of depressive disorders among cancer patients attending the out-patient oncology clinic of a major hospital, and to initiate the development of a valid and practical psychological morbidity screening instrument suitable for local conditions. DESIGN: Survey utilising self-report screening scales and full psychiatric interviews. SETTING: Radiotherapy department, Groote Schuur Hospital. PATIENTS: Breast cancer, head and neck cancer, and lymphoma patients attending out-patient oncology clinics. RESULTS: A total of 456 patients completed the Hospital Anxiety and Depression Scale (HADS). Of that sample, 245 also completed the Beck Depression Inventory (BDI), and 100 were subjected to a structured psychiatric interview. The prevalence of depression in this population is approximately 14%, which is lower than estimates reported elsewhere. Only 14% of the interviewed depressed cases had been identified and treated by the existing health care system, highlighting the need for suitable screening tools. Appropriate screening tools and management strategies for this population are discussed. CONCLUSION: This study highlighted the need for routine screening for depression and the implementation of cost-effective management strategies in oncology settings.

A preliminary investigation of high-school counseling resources on the Cape Peninsula.

In South Africa, counseling and guidance services remain marginalized. The aim of this study was to determine the structure and function of the counseling facilities in high schools on the Cape Peninsula. The first telephone survey comprising 68 representatively and randomly selected schools revealed that 26% of schools had no guidance department, and the mean full-time guidance teacher-pupil ratio was 1:897. The second survey involving 33 randomly selected full-time and part-time guidance teachers from the first sample showed that they could assign on average 14.4 minutes of counselling per pupil in one school year. Analysis of the full-time guidance teachers (N = 22) time allocation revealed that 23% of time was allocated to counseling, 32% to guidance, and 45% to formal teaching and administration. These results suggest that the allocation of personnel and time to counselling are deficient. An implication is that adolescents with psychological problems go undetected and therefore untreated.