Timing of Radiotherapy (RT) After Radical Prostatectomy (RP): Long-term outcomes in the RADICALS-RT trial [NCT00541047]

BACKGROUND

The optimal timing of radiotherapy (RT) after radical prostatectomy for prostate cancer has been uncertain. RADICALS-RT compared efficacy and safety of adjuvant RT versus an observation policy with salvage RT for PSA failure.

METHODS

RADICALS-RT was a randomised controlled trial enrolling patients with ≥1 risk factor (pT3/4, Gleason 7-10, positive margins, pre-op PSA≥10ng/ml) for recurrence after radical prostatectomy. Patients were randomised 1:1 to adjuvant RT ("Adjuvant-RT") or an observation policy with salvage RT for PSA failure ("Salvage-RT") defined as PSA≥0.1ng/ml or 3 consecutive rises. Stratification factors were Gleason score, margin status, planned RT schedule (52.5Gy/20 fractions or 66Gy/33 fractions) and treatment centre. The primary outcome measure was freedom-from-distant metastasis, designed with 80% power to detect an improvement from 90% with Salvage-RT (control) to 95% at 10yr with Adjuvant-RT. Secondary outcome measures were bPFS, freedom-from-non-protocol hormone therapy, safety and patient-reported outcomes. Standard survival analysis methods were used; HR<1 favours Adjuvant-RT.

FINDINGS

Between Oct-2007 and Dec-2016, 1396 participants from UK, Denmark, Canada and Ireland were randomised: 699 Salvage-RT, 697 Adjuvant-RT. Allocated groups were balanced with median age 65yr. 93% (649/697) Adjuvant-RT reported RT within 6m after randomisation; 39% (270/699) Salvage-RT reported RT during follow-up. Median follow-up was 7.8 years. With 80 distant metastasis events, 10yr FFDM was 93% for Adjuvant-RT and 90% for Salvage-RT: HR=0.68 (95%CI 0·43-1·07, p=0·095). Of 109 deaths, 17 were due to prostate cancer. Overall survival was not improved (HR=0.980, 95%CI 0.667-1.440, p=0.917). Adjuvant-RT reported worse urinary and faecal incontinence one year after randomisation (p=0.001); faecal incontinence remained significant after ten years (p=0.017).

INTERPRETATION

Long-term results from RADICALS-RT confirm adjuvant RT after radical prostatectomy increases the risk of urinary and bowel morbidity, but does not meaningfully improve disease control. An observation policy with salvage RT for PSA failure should be the current standard after radical prostatectomy.

Long term outcomes of nonmyeloablative allogeneic stem cell transplantation with TSEB TLI and ATG for Mycosis Fungoides and Sezary Syndrome

Advanced stage (IIB-IVB) Mycosis Fungoides (MF) and Sezary Syndrome (SS) have a poor prognosis with median survival <5 years. We report long-term outcomes of a non-myeloablative allogeneic stem cell transplantation regimen consisting of total skin electron beam therapy, total lymphoid irradiation and antithymocyte globulin. Our prospective cohort consisted of 41 patients with a higher proportion of MF (34MF, 7SS). Acute GVHD Grade 2 to 4 was seen in 31.7% and chronic GVHD Grade 2 to 4 in 24%. The cumulative incidence of non-relapse mortality was 9.8% at 1 year and 12.6% at 2 years. At Day +90 post-transplant 66% of patients had a complete response (CR). With a median post-transplant follow up of 5.27 years, the 5-year overall survival rate was 37.7% (MF 36.7%, SS 57.1%). The 5-year cumulative incidence of progressive disease or relapse was 52.7% in all patients but only 20.8% in those with CR at transplant compared to 70.6% in those not in CR at transplant (p = 0.006). Long term survival is possible in advanced MF and SS with non-myeloablative transplantation and outcomes are improved in patients with CR at transplant.

Mindfulness as an early intervention for hazardous alcohol use among non-treatment seeking Latine emerging adults: A mini-review

The age cohort referred to as emerging adults (ages 18-29 years old) demonstrates the most hazardous alcohol use in the United States (U.S.) Approximately one-third of emerging adults regularly engage in heavy episodic drinking (4/5 drinks in two hours females/males). Compared to their non-Latine White peers, Latine emerging adults in the U.S. report lower rates of heavy episodic drinking (HED) yet are at greater risk of developing a substance use disorder and experience more severe negative consequences from drinking alcohol. Despite their high-risk status, Latine emerging adults are less likely to seek treatment and have less access to innovative health-promoting resources, further exacerbating health inequities. Research has shown that practicing mindfulness can interrupt habituated cognitions, intrusive thinking, and automatic behaviors associated with hazardous drinking. However, Latine representation in MBI trials is minimal. This mini-review explores the potential value of mindfulness as an early intervention for hazardous alcohol use among Latine emerging adults. The review provides future directions for research, highlighting the need to design culturally and developmentally tailored MBIs that can provide a respectful, non-judgmental, and discrimination-free environment that appeals to Latine emerging adults. Additionally, conclusions are drawn regarding the possible benefits of pairing MBI with contingency management strategies to decrease attrition rates in MBI trials.

Participation in a yoga intervention is associated with improved mental health among Latinx adolescents

Latinx youth with mental health disorders have worse outcomes when compared to their White (non-Hispanic) counterparts. Latinx youth also have less access to and lower utilization of mental health services. Emerging research supports the psychological and physical benefits of engaging in yoga and yoga may function as a complimentary treatment option for patients with mental health challenges. However, research assessing the efficacy of yoga and mindfulness is particularly sparse among Latinx youth, who may particularly benefit from mind body awareness activities given barriers to more traditional health approaches. The objective of this quasi-experimental study was to examine the effects of a 12-week Vinyasa flow-based yoga group intervention on anxiety, depression, empathy, and life satisfaction among adolescents receiving outpatient mental health treatment. Adolescents (n = 186; 12-17 years old) were recruited to an active intervention condition (Yoga); a subsequent group of participants (n = 91) were recruited in the same manner to an assessment-only comparison control condition (Comparison). The Yoga group participated in culturally and developmentally tailored group yoga classes for 12 weeks. Structural equation modelling was used to evaluate the main effect intervention response between participants in the two conditions. At the post-intervention assessment, after controlling for baseline levels of outcome variables (i.e., depression, anxiety, empathy, and life satisfaction), on average participants in the yoga condition reported: less depression symptoms (B = -1.54, p = 0.008), less anxiety symptoms (B = -0.75, p = 0.048), greater empathy (B = 1.32, p = 0.025) and greater life satisfaction (B = 0.30, p = 0.013) as compared to the Comparison condition. Yoga interventions can be an acceptable and feasible modality for promoting well-being and reducing mental health problems among Latinx youth.

Tau phosphorylation and PAD exposure in regulation of axonal growth

Introduction: Tau is a microtubule associated phosphoprotein found principally in neurons. Prevailing dogma continues to define microtubule stabilization as the major function of tau in vivo, despite several lines of evidence suggesting this is not the case. Most importantly, tau null mice have deficits in axonal outgrowth and neuronal migration while still possessing an extensive microtubule network. Instead, mounting evidence suggests that tau may have a major function in the regulation of fast axonal transport (FAT) through activation of neuronal signaling pathways. Previous studies identified a phosphatase activating domain (PAD) at the tau N-terminal that is normally sequestered, but is constitutively exposed in tauopathies. When exposed, the PAD activates a signaling cascade involving PP1 and GSK3β which affects cellular functions including release of cargo from kinesin. Furthermore, we discovered that PAD exposure can be regulated by a single phosphorylation at T205. Exposure of the PAD is an early event in multiple tauopathies and a major contributing factor to neurodegeneration associated with tau hyperphosphorylation. However, effects of tau PAD exposure on anterograde FAT raised the interesting possibility that this pathway may be a mechanism for physiological regulation of cargo delivery through site-specific phosphorylation of tau and transient activation of PP1 and GSK3β. Significantly, there is already evidence of local control of PP1 and GSK3β at sites which require cargo delivery. Methods: To investigate this hypothesis, first we evaluated cellular localization of tau PAD exposure, pT205 tau phosphorylation, and active GSK3β in primary hippocampal neurons during development. Second, we analyzed the axonal outgrowth of tau knockout neurons following transfection with full length hTau40-WT, hTau40-ΔPAD, or hTau40-T205A. Results and Discussion: The results presented here suggest that transient activation of a PP1-GSK3β signaling pathway through locally regulated PAD exposure is a mechanism for cargo delivery, and thereby important for neurite outgrowth of developing neurons.

Feasibility, acceptability and preliminary impact of mindfulness-based yoga among Hispanic/Latinx adolescents

BACKGROUND

The Hispanic/Latinx population constitutes the fastest growing ethnic/racial minority group in the United States (U.S.). Compared to their non-Hispanic/Latinx White counterparts, Hispanic/Latinx youth experience more depression and anxiety, and have more unmet mental health needs (88% vs 76%). Emerging research supports the psychological and physical benefits of mind-body awareness training to enhance well-being and mental health, but almost no studies have recruited ethnic/racial minority samples.

PURPOSE

The current study examined the feasibility, acceptability and preliminary impact of a mindfulness-based yoga program among Hispanic/Latinx public high school students.

PROCEDURES

Participants (N = 187) were recruited from a local public high school in a large multi-ethnic urban school district in the Southeast U.S. and participated in 6 weekly hour-long sessions of mindfulness-based yoga. Participants completed assessments at pretest and one month after program completion.

MAIN FINDINGS

The sample was predominantly Hispanic/Latinx (95%) and female (64%), on average 15.2 years old (SD = 1.3), and 51% were born outside the U.S. Participants reported on average a 14.2% reduction in depressive symptoms (pretest mean = 5.51, posttest mean = 4.73, p = .032, Cohen's d = 0.2), a 14.9% reduction in anxiety symptoms (pretest mean = 9.90, posttest mean = 8.42, p = .005, Cohen's d = 0.2), and a 21.9% reduction in stress (pretest mean = 9.66, posttest mean = 7.54, p < .001, Cohen's d = 0.5).

CONCLUSION

These findings provide support for the effectiveness of a mindfulness-based yoga program for Hispanic/Latinx adolescents, a medically underrepresented group experiencing significant mental health disparities.

The effect of joint translation constraint on within-participant variability of kinematics and kinetics during running in cerebral palsy

BACKGROUND

Biomechanical data in cerebral palsy are inherently variable but no optimal model of translational joint constraint has been identified. The primary aim of this study was to determine which model of translational joint constraint resulted in the lowest within-participant variability of lower limb joint angles and moments. The secondary aim was to determine which model best distinguished known functional groups in Cerebral Palsy.

METHODS

Three models (three degrees of freedom, six degrees of freedom and six degrees of freedom with specified joint translation constraint) were applied to data from running trials of 40 children with cerebral palsy.

FINDINGS

Joint angle standard deviations were largest using the six degrees of freedom model and smallest using the constrained six degrees of freedom model (p < 0.050). For all joints in all planes of motion, joint moment standard deviations were largest using the six degrees of freedom model and smallest using the constrained six degrees of freedom model; standard deviations using the constrained model were smaller than the three degrees of freedom model by 10-30% of moment magnitude (0.01-0.03 Nm/kg; p < 0.001). The six degrees of freedom models distinguished functional subgroups with larger effect size than the three degrees of freedom model only for hip power generation in swing.

INTERPRETATION

A model with specified joint constraint minimized within-participant variability during running and was useful for detecting differences in functional capacity in cerebral palsy.

Music Education as a Path to Positive Youth Development: An El Sistema-Inspired Program

The El Sistema music education philosophy links positive individual and social development through musical education. This study is a longitudinal examination of the impact of participation in an El Sistema-inspired program, the Miami Music Project, on positive youth development. We hypothesized that over the course of a school year, participation in ensemble-based after-school music programming would significantly enhance factors associated with positive youth development. Specifically, we evaluated social emotional constructs aligned with the Five Cs of Positive Youth Development: Competence, Confidence, Caring, Character, and Connection. Results revealed that participants showed significant increases across all five Cs over the course of the year. Additionally, findings showed that Miami Music Project students showed greater enhancements over time in Character, Competence and Caring when compared to a group of youth who did not participate in music education. This study presents empirical documentation of the numerous meaningful social and emotional enhancements that participation in an El Sistema-inspired program is engendering among youth. In this type of rigorous orchestral model of musical instruction, youth seem to acquire not only cognitive benefits but also a host of social and emotional enhancements, ostensibly from learning in an environment that requires disciplined social cohesion. These findings provide insight into the holistic approach foundational to the El Sistema philosophy and adds to our overall understanding of musical instruction in important ways.

Hispanic Students' Perceptions About HIV/STI Testing and Prevention: A Mixed-Methods Study in a Hispanic-Serving University

Hispanic young adults in the United States are disproportionately affected by HIV and should be considered a priority for prevention efforts. The purpose of this study was to explore perceptions and beliefs of English-speaking students (aged 18-24 years) at a Hispanic-serving university about HIV/sexually transmitted infection (STI) testing and prevention to increase acceptance and adoption of services. Four major themes emerged from four qualitative focus groups (n = 30 students) and were corroborated by an optional anonymous survey (n = 24 surveys): (a) preferences for HIV/STI testing services, (b) essential HIV/STI testing information, (c) preferred delivery method of HIV/STI testing information, and (d) culturally appropriate message design with Hispanic young adults. Findings suggest that Hispanic young adults perceive accessible testing to be important to their community and view normalization of these services as a necessary component of successful adoption and adherence. Although flyers were reported as a practical means for distributing on-campus testing and service information, social media was endorsed as one of the most effective ways to reach young adults. Among participants, there was less consensus regarding the need for cultural tailoring. Results provide practical insights into the development and application of health promotion strategies with an ethnic minority group and demonstrate how a mixed-methods approach can be employed to inform health promotional efforts.

Developing an SMS Intervention for the Prevention of Underage Drinking: Results From Focus Groups

BACKGROUND

There is growing evidence that text messaging-"short message service" (SMS)-is useful for health promotion and behavior change. SMS has become a preferred channel of communication among adolescents. Despite burgeoning interest, there remains a critical need for formative research regarding developmentally and culturally appropriate SMS-based health promotion with teenagers.

OBJECTIVES

The primary objective was to develop SMS message protocols and procedures effective for reducing underage drinking among Hispanic teens. Using focus groups, we sought our target population's perspectives on SMS parameters including scheduling, frequency, content, themes, and confirmation-of-receipt.

METHOD

We conducted, recorded, and transcribed six mixed-gender focus groups (20 adolescents, 4-5 per group) recruited from the Division of Adolescent Medicine at Miami Children's Hospital. Alcohol-related and "attention control" text messages were assembled from two sources (http://www.mobilehealth4youth.org and the existing literature); these SMSs, along with SMS procedures, were the focus of discussion. The recordings and transcription were reviewed by two researchers who employed a qualitative iterative process analytical approach.

RESULTS

Findings revealed distinct preferences among teenagers about the scheduling, frequency, content, themes, and confirmation-of-receipt of SMSs. Moreover, teens were most enthusiastic about SMSs that addressed alcohol-related knowledge, self-efficacy, social support, or future orientation. Conclusion/Importance: Seeking our target population's perspectives on SMS parameters was essential for developing SMS message protocols and procedures with potential effectiveness for reducing underage drinking among Hispanic teens. It is strongly recommended that researchers or clinicians considering SMS-based interventions conduct a similar formative process prior to implementation.

Differences in the use of vision and proprioception for postural control in autism spectrum disorder

BACKGROUND

People with autism spectrum disorders (ASDs) also have poorer fundamental motor skills. The development of postural control underlies both social and motor skills. All three elements are facilitated by the active use of visual information. This study compares how adults with ASD and typically developed adults (TDAs) respond to a postural illusion induced using neck vibration. Adults with ASD unlike the TDA, were not expected to correct the illusion using vision.

METHODS

The study used intermittent (15off, 5on) posterior neck vibration during 200 s of quiet stance to induce a postural illusion. In TDAs and only in the absence of vision this protocol induces a forward body lean. Participants (12 ASD, 20 TDA) undertook four conditions combining vibration and visual occlusion.

RESULTS

As predicted, TDA were only affected by the postural illusion when vision was occluded (vibration condition: vision occluded (n=1) p=0.0001; vision available (n=3) p>0.2466). Adults with ASD were affected by the postural illusion regardless of the availability of vision (all conditions p<0.0007).

CONCLUSIONS

Our findings indicated the adults with ASD did not use visual information to control standing posture. In light of existing evidence that vision-for-perception is processed typically in ASD, our findings support a specific deficit in vision-for-action. These findings may explain why individuals with ASD experience difficulties with both social and motor skills since both require vision-for-action. Further research needs to investigate the division of these visual learning pathways in order to provide more specific intervention opportunities in ASD.

Treatment Process Predictors of Program Completion or Dropout among Minority Adolescents Enrolled in a Brief Motivational Substance Abuse Intervention

This study documented significant differences in alliance in a predominantly Latino sample of adolescents who either completed or dropped out of a Guided Self-Change treatment program. Therapeutic alliance, working alliance and patient involvement were assessed via ratings of audio-recorded segments of participants' counseling sessions. Descriptive discriminant function analysis identified working alliance goals, patient participation and therapist warmth and friendliness variables as significantly predictive of completion status. These results were confirmed via follow-up logistic regression analyses. The use of brief clinical tools to monitor and manage alliance among adolescents receiving treatment who are at risk for drop-out is discussed.

Motivation for reducing substance use among minority adolescents: targets for intervention

Motivation to change substance use is considered to be one of the most important predictors of client readiness for alcohol and other drug treatment and ability to benefit from treatment. Enhancing motivation to change substance use is an important emphasis of many substance use intervention programs. The specific factors predicting motivation to change substance use remain largely unidentified and poorly understood, particularly among racial/ethnic minority youth. This study examines the influence of adolescent and parental factors on motivation to change substance use among 310 alcohol-using and/or drug-using racial/ethnic minority adolescent males. The analytic plan involved the use of structural equation modeling. Adolescents' motivation to change substance use was influenced directly and indirectly by parental factors, as well as by adolescent substance use severity and externalizing disorders. Findings have implications for treatment with racial/ethnic minority youth, as parental factors may be exceptionally useful targets for interventions aimed at enhancing motivation to reduce substance use among these at-risk youth.

Size does matter: can we reduce the radiotherapy field size for selected cases of anal canal cancer undergoing chemoradiation?

AIMS

Chemoradiation is the standard of care for the treatment of anal canal cancer, with surgery reserved for salvage. For tumours with uninvolved inguinal nodes, it is standard to irradiate the inguinal nodes prophylactically, resulting in large field sizes, which contribute to acute and late toxicity. The aim of this single-centre retrospective study was to determine if, in selected cases, prophylactic inguinal nodal irradiation could be avoided.

MATERIALS AND METHODS

Between August 1998 and August 2004, 30 patients with biopsy-proven squamous cell anal canal cancer were treated with chemoradiation using one phase of treatment throughout. A three-field beam arrangement was used without attempting to treat the draining inguinal lymph nodes prophylactically. The radiotherapy dose prescribed was 50Gy in 25 daily fractions over 5 weeks. Concomitant chemotherapy was delivered with the radiation using mitomycin-C 7-12mg/m(2) on day 1 and protracted venous infusional 5-fluorouracil 200mg/m(2)/day throughout radiotherapy.

RESULTS

All patients had clinically and radiologically uninvolved inguinal and pelvic nodes and all had primary lesions that were T3 or less. The median age at diagnosis was 65 years (range 41-84). The median follow-up was 41 months (range 24-113). The mean posterior field size was 14x15cm and the mean lateral field size was 12x15cm. All patients achieved a complete response. Ninety-four per cent of patients (28/30) were alive and disease free. The two patients who died did so of unrelated causes and were disease free at death. Four patients relapsed and all were salvaged with surgery; two for local disease requiring abdominoperineal resection, one with an inguinal nodal relapse requiring inguinofemoral block dissection and one for metastatic disease to the liver who underwent liver resection.

CONCLUSIONS

This single-centre retrospective study supports the treatment for selected cases of anal canal cancer with smaller than standard radiation fields, avoiding prophylactic inguinal nodal irradiation. Hopefully this will translate into reduced acute and late toxicity. In future studies we would suggest that consideration is given as to whether omission of prophylactic inguinal nodal irradiation for early stage tumours should be explored.

Effects of abdominal muscle fatigue on anticipatory postural adjustments associated with arm raising

Anticipatory postural adjustments (APAs) are postulated to ameliorate the effects of the disturbance to posture caused by voluntary movement. The primary hypothesis tested in our study was that the magnitude of anticipatory trunk muscle activity is altered by abdominal muscle fatigue. A subsidiary aim of the present study was to examine the directional nature of APAs and use this information to elucidate the central or peripheral nature of changes in postural muscle activity associated with abdominal muscle fatigue. The present study was a within subject design, where abdominal muscle fatigue was induced by a static abdominal curl. Surface EMG was used to assess postural muscle activity in the following trunk muscles; rectus abdominis, erector spinae and internal oblique. Following abdominal muscle fatigue, the magnitude of muscle activity during APAs was significantly reduced by 20% in both the rectus abdominis (fatigued muscle) and the erector spinae (not fatigued) indicating a central rather than peripheral fatigue effect on muscle activity. Abdominal muscle fatigue also induced a 30% increase in the baseline muscle activity of the internal oblique. The changes in magnitude of APA muscle activity may reflect a change in system gain or a change in postural control perhaps related to a change in perceived postural stability. An increase in baseline muscle activity in the internal oblique may compensate partially for the reduction in APAs.

Permanent prostate brachytherapy: a century of technical evolution

PURPOSE

To summarise the practical aspects of the development of techniques of interstitial permanent prostate brachytherapy (PPB) implantation. Prostate brachytherapy dates back to Pasteau's publication in 1913 describing the insertion of a radium capsule into the prostatic urethra to treat carcinoma of the prostate. Various implantation methods were employed but with unsatisfactory results until the development of the transrectal ultrasound in the 1980s. The subsequent two-stage Seattle technique allowed for a planned homogenous distribution of radioactive sources throughout the gland resulting in biochemical control comparable to surgical and external beam radiotherapy series. With the advent of advanced computer software and improved imaging, the technique has developed accordingly to a single stage procedure with on-table dosimetric assessment. The principles of targeting dose to the prostate while avoiding surrounding organs at risk remain as relevant today as nearly a century ago. There is an array of techniques to consider for the novice PPB provider. Whether the evolution of PPB techniques will translate into improved biochemical control is yet to be seen.

Using combined x-ray and MR imaging for prostate I-125 post-implant dosimetry: phantom validation and preliminary patient work

Post-implantation dosimetry is an important element of permanent prostate brachytherapy. This process relies on accurate localization of implanted seeds relative to the surrounding organs. Localization is commonly achieved using CT images, which provide suboptimal prostate delineation. On MR images, conversely, prostate visualization is excellent but seed localization is imprecise due to distortion and susceptibility artefacts. This paper presents a method based on fused MR and x-ray images acquired consecutively in a combined x-ray and MRI interventional suite. The method does not rely on any explicit registration step but on a combination of system calibration and tracking. A purpose-built phantom was imaged using MRI and x-rays, and the images were successfully registered. The same protocol was applied to three patients where combining soft tissue information from MRI with stereoscopic seed identification from x-ray imaging facilitated post-implant dosimetry. This technique has the potential to improve on dosimetry using either CT or MR alone.

The discovery of a galaxy-wide superwind from a young massive galaxy at redshift z ≈ 3

High-velocity galactic outflows, driven by intense bursts of star formation and black hole accretion, are processes invoked by current theories of galaxy formation to terminate star formation in the most massive galaxies and to deposit heavy elements in the intergalactic medium. From existing observational evidence (for high-redshift galaxies) it is unclear whether such outflows are localized to regions of intense star formation just a few kiloparsecs in extent, or whether they instead have a significant impact on the entire galaxy and its surroundings. Here we present two-dimensional spectroscopy of a star-forming galaxy at redshift z = 3.09 (seen 11.5 gigayears ago, when the Universe was 20 per cent of its current age): its spatially extended Lyalpha line emission appears to be absorbed by H i in a foreground screen covering the entire galaxy, with a lateral extent of at least 100 kpc and remarkable velocity coherence. This screen was ejected from the galaxy during a starburst several 10(8) years earlier and has subsequently swept up gas from the surrounding intergalactic medium and cooled. This demonstrates the galaxy-wide impact of high-redshift superwinds.

A prognostic index that predicts outcome following palliative whole brain radiotherapy for patients with metastatic malignant melanoma

To determine the outcome of patients with metastatic malignant melanoma (MMM) treated with palliative whole brain radiotherapy (WBRT) and to identify factors that predict treatment outcome to assist future trial design, a retrospective study was performed on patients with MMM who received WBRT at the Royal Marsden Hospital between 1998 and 2003. Data regarding patient factors, tumour factors and survival were collected. A total of 112 patients were identified and full data were available for 102 patients. The median age was 53 years (range 25–81 years), 66.7% were male and 33.3% female. The median dose prescribed was 20 Gy in five fractions as a mid-plane dose. The median survival after WBRT for the whole group was 51 days (range 3–1386). In an attempt to define prognostic groups, we used the validated RTOG recursive partitioning analysis (RPA) classification for brain metastasis (class 1: Karnofsky Performance Score (KPS) ⩾70%, age <65 years with no extracranial metastasis; class 3: KPS <70%; class 2: all others). The median survivals were 151, 71 and 21 days for RPA class 1, 2 and 3, respectively (P<0.001). Multivariate analysis showed that RPA class, leptomeningeal involvement, presence and number of extracranial metastatic sites and progressive disease in the brain on imaging before WBRT are important independent predictive factors. A prognostic index was derived from these factors that allowed identification of patients unlikely to benefit from WBRT. In conclusion, the RTOG RPA classification is valid when applied to patients with MMM. Patients in RPA class 1 and good prognosis class 2 are likely to benefit from palliative WBRT and should be considered for entry into trials that aim to improve duration of response. We identified that patients with RPA class 3, leptomeningeal involvement or RPA class 2 with poor prognostic index are unlikely to benefit from palliative WBRT.

Current Opinion on Adjuvant and Salvage Treatment after Radical Prostatectomy

AIMS

The role of postoperative radiotherapy and hormone treatment after radical prostatectomy is uncertain, with no good evidence base to guide practice. In particular, it is not known whether a blanket policy of adjuvant therapy offers any advantage over a selective approach using salvage treatment in people who develop biochemical failure. Furthermore the technique for postoperative radiotherapy to the prostate bed has not been well described. We surveyed the opinion of UK clinical oncologists to describe current practice, with a view to informing the design of clinical trials in this setting.

MATERIALS AND METHODS

A questionnaire was designed to elicit the opinion and clinical practice of UK clinical oncologists on the use of radiotherapy and hormone therapy after radical prostatectomy. The questionnaire was distributed to the delegates at the British Institute of Radiology Conference 'Contemporary issues in Prostate Cancer Radiotherapy' on 9 May 2003.

RESULTS

Forty-nine out of 70 (70%) clinical oncologists completed the questionnaire. With an undetectable postoperative prostate-specific antigen (PSA) less than 0.04 ng/ml, opinion was divided on the role of adjuvant therapy. For example, adjuvant radiotherapy was recommended by 51% (25/49) of respondents for cases with pT3 margin positive disease. When recommending adjuvant radiotherapy, 60% (59/99) recommended hormone therapy in addition. In cases with an asymptomatic rising PSA after radical prostatectomy who had not received adjuvant therapy, 93% (43/46) recommended salvage radiotherapy, but the PSA threshold for recommending such treatment varied widely. The two most common dose-fractionation regimens for salvage radiotherapy to the prostate bed were 62-64 Gy in 2 Gy daily fractions (47%), and 50-55 Gy in 20 fractions (30%).

CONCLUSIONS

Opinion is varied within the UK on the role of radiotherapy and hormone therapy after radical prostatectomy. The results of this survey should inform the design of future clinical trials.

Do the Finapres and Colin radial artery tonometer measure the same blood pressure changes following deflation of thigh cuffs?

The objective of this work was to determine if systematic differences exist between blood pressure time series measured by two non-invasive techniques. Cerebral blood flow autoregulation is often measured while a change in blood pressure is induced by deflation of thigh cuffs. To interpret the result a continuous measurement of arterial blood pressure is required. The Finapres is a non-invasive blood pressure monitor that is often used when assessing autoregulation but there is uncertainty about its reliability. A more recent device, the Colin tonometer, uses radial artery tonometry, which may prove to be a more reliable non-invasive method of obtaining a blood pressure waveform. Twenty healthy volunteers were recruited; blood pressure trends following cuff deflation were measured simultaneously with a Finapres and a Colin tonometer. A significant difference was found between the blood pressure waveforms measured with the two devices. The most striking difference was a slower recovery time measured with the Finapres (Wilcoxon signed rank test P < 0.001). Peripheral vasoaction may be distorting the measurement of blood pressure by the Finapres. This would account for the difference that exists between the techniques. Comparison with a direct arterial line would confirm which non-invasive measurement is more accurate.

Susceptibility of mice deficient in the MHC class II transactivator to infection with Mycobacterium tuberculosis

Major histocompatibility complex (MHC) class II antigen presentation and subsequent CD4+ T-cell activation are critical for acquired immunity to Mycobacterium tuberculosis infection. MHC class II gene expression is primarily controlled by the master transactivator CIITA protein. Without functional CIITA protein, MHC class II expression is lost, impairing immune responses and increasing susceptibility to infection. In this study, we compared protective immune responses of CIITA-deficient mice and wild-type C57BL/6 controls with low dose aerosol M. tuberculosis infection. After aerogenic challenge, CIITA-/- mice failed to limit mycobacterial growth (2.5 and 2.0 log10 > WT lung and spleen CFUs, respectively, at day 58). Lung histopathology involved extensive necrosis, severe pneumonitis and overwhelming inflammation in the gene knockout mice. Mean survival time for CIITA-/- mice was significantly reduced (57 versus >300 days for WT). This extreme sensitivity to tuberculous infection was largely attributed to the absence of CD4+ cells. Flow cytometric studies detected virtually no CD4+ cells in CIITA-/- mouse spleens after infection versus elevated numbers in WT spleens. Failed CD4+ T-cell expansion markedly reduced interferon-gamma (IFN-gamma production in CIITA-/- mice versus WT controls. These results suggest the necessity of a functional CIITA pathway for controlling tuberculous infections and that interventions targeting CIITA expression may be useful antimycobacterial therapeutics.

Peptide nucleic acid probe detection of mutations in Mycobacterium tuberculosis genes associated with drug resistance

The emergence of drug-resistant strains of Mycobacterium tuberculosis is a serious public health problem. Many of the specific gene mutations that cause drug resistance in M. tuberculosis are point mutations. We are developing a PCR-peptide nucleic acid (PNA)-based ELISA as a diagnostic method to recognize point mutations in genes associated with isoniazid and rifampin resistance in M. tuberculosis. Specific point mutation-containing sequences and wild-type sequences of cloned mycobacterial genes were PCR-amplified, denatured, and hybridized with PNA probes bound to microplate wells. Using 15-base PNA probes, we established the hybridization temperatures (50 degrees C-55 degrees C) and other experimental conditions suitable for detecting clinically relevant point mutations in the katG and rpoB genes. Hybridization of PCR-amplified sequences that contained these point mutations with complementary mutation-specific PNAs resulted in significant increases in ELISA response compared with hybridization using wild-type-specific PNAs. Conversely, PCR-amplified wild-type sequences hybridized much more efficiently with wild-type PNAs than with the mutation-specific PNAs. Using the M. tuberculosis cloned genes and PCR-PNA-ELISA format developed here, M. tuberculosis sequences containing point mutations associated with drug resistance can be identified in less than 24 h.

DNA vaccination against tuberculosis: expression of a ubiquitin-conjugated tuberculosis protein enhances antimycobacterial immunity

Genetic immunization is a promising new technology for developing vaccines against tuberculosis that are more effective. In the present study, we evaluated the effects of intracellular turnover of antigens expressed by DNA vaccines on the immune response induced by these vaccines in a mouse model of pulmonary tuberculosis. The mycobacterial culture filtrate protein MPT64 was expressed as a chimeric protein fused to one of three variants of the ubiquitin protein (UbG, UbA, and UbGR) known to differentially affect the intracellular processing of the coexpressed antigens. Immunoblot analysis of cell lysates of in vitro-transfected cells showed substantial differences in the degradation rate of ubiquinated MPT64 (i.e., UbG64 < UbA64 < UbGR64). The specific immune response generated in mice correlated with the stability of the ubiquitin-conjugated antigen. The UbA64 DNA vaccine induced a weak humoral response compared to UbG64, and a mixed population of interleukin-4 (IL-4)- and gamma interferon (IFN-gamma)-secreting cells. Vaccination with the UbGR64 plasmid generated a strong Th1 cell response (high IFN-gamma, low IL-4) in the absence of a detectable humoral response. Aerogenic challenge of vaccinated mice with Mycobacterium tuberculosis indicated that immunization with both the UbA64- and UbGR64-expressing plasmids evoked an enhanced protective response compared to the vector control. The expression of mycobacterial antigens from DNA vaccines as fusion proteins with a destabilizing ubiquitin molecule (UbA or UbGR) shifted the host response toward a stronger Th1-type immunity which was characterized by low specific antibody levels, high numbers of IFN-gamma-secreting cells, and significant resistance to a tuberculous challenge.

Rapid and efficient detection of extra-pulmonary Mycobacterium tuberculosis by PCR analysis

SETTING

The diagnosis of extra-pulmonary tuberculosis (EPTB) remains an important clinical problem, primarily because of the inadequate sensitivity of conventional bacteriologic methods for detecting Mycobacterium tuberculosis in extra-pulmonary specimens.

OBJECTIVE

To evaluate whether a IS6110-based polymerase chain reaction (PCR) method can be utilized to detect M. tuberculosis in non-pulmonary specimens.

DESIGN

Specimens from 286 Mexican patients with a presumptive clinical diagnosis of EPTB were prospectively examined by Ziehl-Neelsen staining, mycobacterial culture on Löwenstein-Jensen slants, and by PCR. The DNA for PCR was extracted by the buffer lysis method and phenol-guanidine thiocyanate-chloroform. Primers that amplify a 200 bp fragment from the insertion-like M. tuberculosis sequence element IS6110 were utilized.

RESULTS

Our results demonstrate that this PCR method is highly specific (100%) for identifying M. tuberculosis from a variety of specimens including cerebrospinal fluid (CSF), pleural fluid, ascitic fluid, pericardial fluid, urine, and lymph node exudate. Moreover, the sensitivity of PCR for detecting M. tuberculosis in CSF (94%), pleural fluid (94%), ascitic fluid and other extrapulmonary specimens (93%) greatly exceeds the sensitivity of conventional smear and culture methods.

CONCLUSION

These results demonstrate that PCR can be a highly specific and sensitive aid in the detection of M. tuberculosis from extra-pulmonary specimens.

Caltech Faint Galaxy Redshift Survey. XI. The Merger Rate to Redshift 1 from Kinematic Pairs

The rate of mass accumulation due to galaxy merging depends on the mass, density, and velocity distribution of galaxies in the near neighborhood of a host galaxy. The fractional luminosity in kinematic pairs combines all of these effects in a single estimator that is relatively insensitive to population evolution. Here we use a k-corrected and evolution-compensated volume-limited sample having an R-band absolute magnitude of Mk,eR</=-19.8+5logh mag drawing about 300 redshifts from the Caltech Faint Galaxy Redshift Survey and 3000 from the Canadian Network for Observational Cosmology field galaxy survey to measure the rate and redshift evolution of merging. The combined sample has an approximately constant comoving number and luminosity density from redshift 0.1 to 1.1 (OmegaM=0.2, OmegaLambda=0.8); hence, any merger evolution will be dominated by correlation and velocity evolution, not density evolution. We identify kinematic pairs with projected separations less than either 50 or 100 h-1 kpc and rest-frame velocity differences of less than 1000 km s-1. The fractional luminosity in pairs is modeled as fL&parl0;Deltav,rp,Mk,er&parr0;&parl0;1+z&parr0;mL, where &sqbl0;fL,mL&sqbr0; are &sqbl0;0.14+/-0.07,0+/-1.4&sqbr0; and &sqbl0;0.37+/-0.7,0.1+/-0.5&sqbr0; for rp</=50 and 100 h-1 kpc, respectively (OmegaM=0.2, OmegaLambda=0.8). The value of mL is about 0.6 larger if Lambda=0. To convert these redshift-space statistics to a merger rate, we use the data to derive a conversion factor to a physical space pair density, a merger probability, and a mean in-spiral time. The resulting mass accretion rate per galaxy (M1,M2>/=0.2M*) is 0.02+/-0.01&parl0;1+z&parr0;0.1+/-0.5M* Gyr-1. Present-day high-luminosity galaxies therefore have accreted approximately 0.15M* of their mass over the approximately 7 Gyr to redshift 1. Since merging is likely only weakly dependent on the host mass, the fractional effect, deltaM&solm0;M approximately 0.15M*&solm0;M, is dramatic for lower mass galaxies but is, on the average, effectively perturbative for galaxies above 1M*.

Propelling novel vaccines directed against tuberculosis through the regulatory process

The development of novel vaccines for use in the prevention and immunotherapy of tuberculosis is an area of intense interest for scientific researchers, public health agencies and pharmaceutical manufacturers. Development of effective anti-tuberculosis vaccines for use in specific target populations will require close cooperation among several different international organizations including agencies responsible for evaluating the safety and effectiveness of new biologics for human use. In this review, the major issues that are addressed by regulatory agencies to ensure that vaccines are pure, potent, safe, and effective are discussed. It is hoped that the comments provided here will help accelerate the development of new effective vaccines for the prevention and treatment of tuberculosis.

Validation of the use of a commercially available kit for the identification of prostate specific antigen (PSA) in semen stains

PSA is currently being used to detect and monitor quantitatively the development of prostate cancer by serum levels of PSA and has also been found to be present in high concentrations in semen. Elegantly simple, sensitive, and reproducible methods have been developed for analysis of the presence of PSA, including the Tandem-E PSA Immunoenzymetric Assay. The most common procedures for the forensic identification of semen have focused on the microscopic detection of sperm, acid phosphatase activity, and immunoelectrophoretic methods for the detection of PSA. Although these methods have been used for many years, there are problems associated with each method. The Tandem-E PSA Immunoenzymetric Assay detected PSA in 100% of the forensic casework fabric samples, 80% of the forensic casework vaginal swabs and 100% of the vasectomized individuals tested. The cut-off value was determined to be 1.77 ng/mL. These results indicate that this method can be used to identify the presence of semen in forensically significant specimens.

Differential effects of heparin on the early and late phases of hepatic ischemia and reperfusion injury in the pig

The mechanisms by which heparin protects the liver during induced episodes of liver ischemia-reperfusion are poorly understood. Previous work in a swine model demonstrated that serum levels of glycohydrolases and lipid peroxide peaked within 3 h after 45 minutes of hepatic ischemia followed by reperfusion. Serum levels of lactate dehydrogenase and aspartate aminotransferase peaked 20-24 h later. The aim of this study was to evaluate the effect of heparin on these two-phases of enzyme release, using a pig model of hepatic ischemia-reperfusion injury. Twenty male swine were divided into control (n = 8) and heparin (n = 12) groups. In the heparin group, heparin was administered prior to and concurrent with ischemia-reperfusion. Following 45 min of hepatic ischemia, the levels of beta-galactosidase, beta-glucosidase, acid phosphatase, purine nucleoside phosphorylase, lipid peroxides, lactate dehydrogenase, and aspartate aminotransferase in serum were monitored for up to 166 h and compared to pre-ischemic and control levels. With heparin infusion, the peak levels of beta-galactosidase, beta-glucosidase, and the lipid peroxide were reduced to 50-60% of the control levels. Acid phosphatase and purine nucleoside phosphorylase activities in serum were reduced to 25% and 60%, respectively. The peak concentrations of lactate dehydrogenase and aspartate aminotransferase were reduced to about 25% of the control level. In addition, the serum enzymes of control pigs did not return to pre-ischemic levels until 2 weeks after hepatic ischemia, while they normalized in less than 1 week in the heparin-treated animals. Systemic heparinization had different protective effects on the first and secondary phases of liver injury. These differences may reflect heparin protection of different types of liver cells. The protection of the parenchymal cells may be the combined result of reduced sinusoidal cell injury and the anticoagulant properties of heparin.

Analysis of ahpC gene mutations in isoniazid-resistant clinical isolates of Mycobacterium tuberculosis

The ahpC genes of 57 clinical isolates and one in vitro mutant of Mycobacterium tuberculosis were evaluated by nucleotide sequence analyses. Although compensatory ahpC promoter mutations were identified in 8 catalase-negative, katG-defective strains, the ahpC genes of 25 catalase-positive, isoniazid-resistant isolates and 25 drug-sensitive strains were not altered.

Chronic illness perception in adolescence: implications for the doctor-patient relationship

OBJECTIVE

To describe the inter-relationship of chronic illness severity as perceived by adolescents with both psychosocial well-being and objective measures of illness severity. Additionally to compared the adolescents' perception of illness severity with how their physicians believe that the adolescents perceive their illness severity.

METHODS

The psychological well-being of 48 adolescents with either cystic fibrosis (CF) or insulin-dependent diabetes mellitus (IDDM) was measured by four standardized questionnaires. The adolescents' perception of severity of illness was measured using an original instrument (PSCI), and this measure was compared to their physicians' estimates of how the adolescents perceived the severity of their illness and clinical illness.

RESULTS

There were 24 patients in both the CF and IDDM groups. Both groups were found to function well psychosocially; although, there were more patients with low self image compared to normative values. Depression and low self image were associated with a greater adolescent perception of illness severity. For both chronic illness groups, physicians' assessment of assumed adolescent perception of disease severity correlated with clinical indices of disease severity and was higher than the perception of illness severity reported by the adolescents. For adolescents with CF, but not with IDDM, perception of severity of chronic illness correlated with clinical indices.

CONCLUSIONS

For adolescents with chronic illness, their perception of illness severity is an important indicator of psychosocial well-being. Physicians do not accurately infer their patients' perception of illness severity.

Site-directed mutagenesis of the katG gene of Mycobacterium tuberculosis: effects on catalase-peroxidase activities and isoniazid resistance

Recent studies examining the molecular mechanisms of isoniazid (INH) resistance in Mycobacterium tuberculosis have demonstrated that a significant percentage of drug-resistant strains are mutated in the katG gene which encodes a catalase-peroxidase, and the majority of these alterations are missense mutations which result in the substitution of a single amino acid. In previous reports, residues which may be critical for enzymatic activity and the drug-resistant phenotype have been identified by evaluating INH-resistant clinical isolates and in vitro mutants. In this study, site-directed mutagenesis techniques were utilized to alter the wild-type katG gene from M. tuberculosis at 13 of these codons. The effects of these mutations were determined using complementation assays in katG-defective, INH-resistant strains of Mycobacterium smegmatis and Mycobacterium bovis BCG. This mutational analysis revealed that point mutations in the katG gene at nine of the 13 codons can cause drug resistance, and that enzymatic activity and resistance to INH are inversely related. In addition, mutations in the mycobacterial catalase-peroxidase which reduce catalase activity also decrease peroxidase activity.

Rapid detection of Mycobacterium avium in stool samples from AIDS patients by immunomagnetic PCR

Direct PCR detection of bacteria in clinical samples is often hindered by the presence of compounds that inhibit the PCR. To improve and accelerate the diagnosis of Mycobacterium avium-M. intracellulare complex infections, an immunomagnetic PCR (IM-PCR) assay was developed. This IM-PCR procedure combines the separation of mycobacteria by antimycobacterial monoclonal antibody coupled to magnetic beads with an M. avium-M. intracellulare complex-specific PCR protocol based on 16S rRNA gene sequences. As few as 10 M. avium bacilli were detected in spiked human stool samples, a clinical specimen usually refractory to conventional PCR analysis, by the IM-PCR method. Moreover, M. avium organisms were detected in about 24 h in 18 of 22 culture-confirmed fecal samples from AIDS patients. This IM-PCR protocol should allow for the rapid and sensitive detection of M. avium isolates in clinical specimens.

Compensatory ahpC gene expression in isoniazid-resistant Mycobacterium tuberculosis

Mutations that eliminate KatG catalase-peroxidase activity prevent activation of isoniazid and are a major mechanism of resistance to this principal drug for the treatment of Mycobacterium tuberculosis infections. However, the loss of KatG activity in clinical isolates seemed paradoxical because KatG is considered an important factor for the survival of the organism. Expression of either KatG or the recently identified alkyl hydroperoxidase AhpC was sufficient to protect bacilli against the toxic effects of organic peroxides. To survive during infection, isoniazid-resistant KatG mutants have apparently compensated for the loss of KatG catalase-peroxidase activity by a second mutation, resulting in hyperexpression of AhpC.

The absence of genetic markers for streptomycin and rifampicin resistance in Mycobacterium avium complex strains

Mycobacterium avium, Mycobacterium intracellulare complex (MAC) bacilli are an important cause of bacteraemia in AIDS patients but treatment is complicated by their resistance to the usual antimycobacterial agents. In this study of 20 strains of MAC none was found to have the mutations associated with resistance to rifampicin and streptomycin in M. tuberculosis suggesting that MAC have unique mechanisms for resistance to these agents.

Cloning, sequence analysis, overproduction in Escherichia coli and enzymatic characterization of the RNase HI from Mycobacterium smegmatis

Activity gel analysis of cell extracts from slow- and fast-growing mycobacteria confirmed the presence of several RNase H activities in both classes of organism. The rnhA gene from Mycobacterium smegmatis (Ms) was subsequently cloned using an internal gene segment probe [Mizrahi et al., Gene 136 (1993) 287-290]. The gene encodes a polypeptide of 159 amino acids that shares 50% identity with the RNase HI from Escherichia coli (Ec). However, unlike its counterparts from Gram- bacteria, Ms rnhA does not form an overlapping divergent transcriptional unit with dnaQ (encoding the epsilon (proofreading) subunit of DNA polymerase III). Ms RNase HI was overproduced in Ec as an enzymatically active maltose-binding protein (MBP) fusion protein which cleaved the RNA strand of an RNA.DNA hybrid with a similar site selectivity to that of its Ec homologue.

Characterization of the katG and inhA genes of isoniazid-resistant clinical isolates of Mycobacterium tuberculosis

Resistance to isoniazid in Mycobacterium tuberculosis has been associated with mutations in genes encoding the mycobacterial catalase-peroxidase (katG) and the InhA protein (inhA). Among the 26 isoniazid-resistant clinical isolates evaluated in this study, mutations in putative inhA regulatory sequences were identified in 2 catalase-positive isolates, katG gene alterations were detected in 20 strains, and 4 isolates had wild-type katG and inhA genes. Mutations in the katG gene were detected in all 11 catalase-negative isolates: one frameshift insertion, two partial gene deletions, and nine different missense mutations were identified. An arginine-to-leucine substitution at position 463 was detected in nine catalase-positive isolates. However, site-directed mutagenesis experiments demonstrated that the presence of a leucine at codon 463 did not alter the activity of the M. tuberculosis catalase-peroxidase and did not affect the capacity of this enzyme to restore isoniazid susceptibility to isoniazid-resistant, KatG-defective Mycobacterium smegmatis BH1 cells. These studies further support the association between katG and inhA gene mutations and isoniazid resistance in M. tuberculosis, while also suggesting that other undefined mechanisms of isoniazid resistance exist.

A highly immunogenic putative Mycobacterium kansasii lipoprotein

The resurgence of tuberculosis, the emergence of multiple drug resistant tuberculosis, and the increasing prevalence of mycobacterial disease in AIDS patients have increased the importance of defining new mycobacterial antigens that can be utilized in the development of improved diagnostic reagents and more effective vaccines. In this report, a highly immunogenic Mycobacterium kansasii protein (MK35) and the gene encoding this antigen were characterized. MK35 gene probes reacted with genomic DNA from M. avium, M. bovis BCG, M. intracellulare and M. tuberculosis but not with DNA isolated from nine other mycobacterial species. Nucleotide sequence analysis showed that the MK35 gene encodes a 26 kDa protein which contains a consensus bacterial lipoprotein processing sequence. In addition, detergent-phase separation studies strongly suggested that MK35 is a lipoprotein. Skin test assays demonstrated that MK35 elicited a strong response in guinea pigs sensitized with M. kansasii but did not react in M. tuberculosis-sensitized guinea pigs. These results further suggest that mycobacterial lipoproteins are immunogenic antigens that should be considered in the development of new mycobacterial vaccines and diagnostic reagents.

Age-dependent humoral responses of children to mycobacterial antigens

In the United States, disseminated infection with environmental mycobacteria, including the Mycobacterium avium complex, is the most common opportunistic bacterial infection seen in AIDS patients. However, the source and relative degree of exposure to environmental mycobacteria during childhood are unknown. To examine the age-related exposure to mycobacteria, we obtained serum samples from 150 children ranging in age from 6 months to 18 years. Each sample was tested against both M. avium (serovar 1) sonic extracts and mycobacterial lipoarabinomannan, using an enzyme-linked immunosorbent assay (ELISA). All serum samples were also subjected to immunoblot analysis with the sonic extract antigen. These studies established that elevated ELISA values (P < 0.0001) and increased immunoblot reactivity (P < 0.0001) against mycobacterial antigens were both associated with increasing age. The seroreactivity differences were most striking when comparing the age groups of children below the age of 6 with the older age groups. Our results suggest that the development of humoral immune responses to mycobacterial antigens in children correlates with increasing age and that there may be an environmental factor predisposing to mycobacterial exposure which is related to advancing age.

Molecular mechanisms of isoniazid resistance in Mycobacterium tuberculosis and Mycobacterium bovis

Genetic and biochemical studies have suggested a link between reduced catalase activity and resistance to isoniazid in Mycobacterium tuberculosis. In this study, we examined the molecular mechanisms of resistance to isoniazid with six in vitro mutants of the M. tuberculosis complex (Mycobacterium bovis and M. tuberculosis). Five of six mutants resistant to isoniazid were negative by catalase assays. Immunoblot analyses using a polyclonal antibody against the katG gene product (catalase-peroxidase) demonstrated that the enzyme is not produced in four of these isoniazid-resistant strains. A complete deletion of the katG gene was detected in only one of these isoniazid-resistant M. tuberculosis complex strains by Southern blot analyses. In two other resistant strains, partial deletions of the katG gene were identified. A point mutation which resulted in the insertion of a termination codon in the katG coding sequence caused a catalase-negative phenotype in a fourth strain. Of the two resistant strains which produce the enzyme, one was shown to be negative by a catalase assay. Single-stranded conformational polymorphism and DNA sequence analyses identified a mutation in the katG gene of this strain which may contribute to reduced enzymatic activity and subsequent isoniazid resistance. These data demonstrate that genetic alterations to the katG gene other than complete deletions are prevalent and may contribute significantly to the number of cases of isoniazid-resistant tuberculosis.

Glucocorticoids and insulin regulate expression of the human gene for insulin-like growth factor-binding protein-1 through proximal promoter elements

Glucocorticoids stimulate, while insulin inhibits, the hepatic transcription of insulin-like growth factor-binding protein-1 (IGFBP-1). In the present studies, human HEP G2 hepatoma cells were transiently transfected with human (h)IGFBP-1 promoter constructs. Activity of a construct containing the first 1205 base pairs (bp) of the hIGFBP-1 promoter was stimulated 6-9.5-fold by dexamethasone, and this increase was inhibited approximately 76% by insulin. Deletion and site-directed mutations of the hIGFBP-1 promoter (a) identified two glucocorticoid response elements, located within the first 200 bp of the promoter, which are essential for dexamethasone-stimulated promoter activity and which specifically bind human glucocorticoid receptor; (b) showed that a recently characterized insulin-responsive element, located approximately 110 bp 5' to the transcription start site (Suwanichkul, A., Morris, S.L., and Powell, D. R. (1993) J. Biol. Chem. 268, 17063-17068), confers the entire inhibitory effect of insulin not only on basal but also on glucocorticoid-stimulated promoter activity; and (c) showed that this insulin-responsive element is essential for maximal glucocorticoid-stimulated activity. These studies suggest that the interaction of proteins that bind to a cluster of cis elements located in the first 200 bp of the hIGFBP-1 promoter are of major importance in modulating the opposing effects of glucocorticoids and insulin on hepatic hIGFBP-1 expression.