Evaluating the intensity of the 803-keV γ ray of 210Po using a 4παβ(LS)-γ(HPGe) measurement system

The absolute intensity for the 803-keV γ ray of ²¹⁰Po was evaluated by α-γ coincidence technique. A liquid sample with a known amount of ²¹⁰Po embedded in scintillation fluid was measured in a coincidence-based system that comprises a Liquid Scintillator (LS) detector and a High-Purity Germanium (HPGe) detector. A photo-reflector assembly that contains the ²¹⁰Po sample provides 100% efficiency for detecting the α particles. The combination between the HPGe and the LS detectors allows to reject non-coincident α-γ events while maintaining high resolution γ spectroscopy. Consequently, the faint 803-keV photopeak from ²¹⁰Po could be observed in a background-free environment, and its intensity could be evaluated with good accuracy. Sample measurements were carried out over nine months to gather statistics and verify the reliability of the experimental procedure. The absolute intensity of the 803-keV line was found to be (1.22 ± 0.03) × 10^-5, in excellent agreement with the adopted value in a recent data compilation and consistent with previous experimental works.

Evaluating the intensity of the 'prompt' 140.5 keV γ-ray of 99Mo using a 4παβ(LS)-γ(HPGe) measurement system

The absolute intensity for the 'prompt' 140.5 keV gamma-ray of ⁹⁹Mo was evaluated using the β-γ coincidence technique. A liquid sample of ⁹⁹Mo was prepared from a⁹⁹Mo/^99mTc generator and measured in a 4παβ(LS)-γ(HPGe) system that comprises a Liquid Scintillator (LS) detector and a High-Purity Germanium (HPGe) detector. The sample was introduced into scintillation fluid embedded in a photo-reflector assembly that provides almost 100% efficiency for detecting β particles (in the energy range of intreset). The combination of the HPGe and the LS detectors provided a highly effective rejection mechanism for non-coincident events. Thereby, the distinction between the detected 140.5 keV events originating from decays of ^99mTc (IT) and those from transitions bypassing the metastable state could be obtained and the 'prompt' intensity was evaluated directly. The system was calibrated for detecting β particles and γ-rays using radioactive sources of known activities and having identical geometry as the sample containing ⁹⁹Mo. The absolute intensity of the 'prompt' 140.5 keV was found to be (5.21 ± 0.02_stat±0.16_sys)%, in good agreement with results from more recently reported works.

High power high voltage bias-T for half wave resonators and radio frequency quadrupole couplers

High power high voltage bias-T units capable of delivering up to 100 kW CW RF power at 176 MHz and up to 4 kV DC were developed at the Soreq Nuclear Research Center for the Soreq Applied Research Accelerator Facility linac. Two separate bias-T units with different requirements were designed for the radio frequency quadrupole couplers and the half wave resonator couplers. The purpose of this bias-T is to prevent multipacting phenomena by application of a high voltage DC bias to inner conductors of RF couplers. Underlying design principles, indigenous development, and successful off-line and on-line tests results are presented.

Neutron Capture on the s-Process Branching Point ^{171}Tm via Time-of-Flight and Activation

The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable ^{171}Tm (t_{1/2}=1.92  yr) is part of the branching around mass A∼170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of ^{171}Tm at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (n_TOF) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time-of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384(40) mb, with which the estimation from the n_TOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A∼170 branching, namely, the ^{171}Yb abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation.

Study of Astrophysical s-Process Neutron Capture Reactions at the High-Intensity SARAF-LiLiT Neutron Source

We report on recent experiments at the Soreq Applied Research Accelerator Facility Liquid-Lithium Target (SARAF-LiLiT) laboratory dedicated to the study of s-process neutron capture reactions. The kW-power proton beam at 1.92 MeV (1-2 mA) from SARAF Phase I yields high-intensity 30 keV quasi-Maxwellian neutrons (3-5×1010 n/s). The high neutron intensity enables Maxwellian averaged cross sections (MACS) measurements of low-abundance or radioactive targets. Neutron capture reactions on the important s-process branching points 147Pm and 171Tm were investigated by activation in the LiLiT neutron beam and γ-measurements of their decay products. MACS values at 30 keV extracted from the experimental spectrum-averaged cross sections are obtained and will be discussed. The Kr region, at the border between the so-called weak and strong s-process was also investigated. Atom Trap Trace Analysis (ATTA) was used for the first time for the measurement of a nuclear reaction cross section. After activation in the quasi-Maxwellian neutron flux at SARAF-LiLiT, isotopic ratios were determined for 81Kr(230 ky)/80Kr and 85gKr(10.8 y)/84Kr. The latter ratio was confirmed both by low-level β counting and γ spectrometry. The shorter-lived capture products 79,85m,87Kr were detected by γ -spectrometry and the corresponding neutron-capture MACS of the respective target nuclei 78,84,86Kr were determined. The MACS of the 80Kr(n, γ)81Kr and 84Kr(n, γ)85gKr reactions are still under study. The partial MACS leading to 85mKr(4.5 h) measured in this experiment has interesting implications since this state decays preferentially by γ decay (79%) to 85Rb on a faster time scale than does 85gKr and behaves thus as an s-process branching point.

Stellar ^{36,38}Ar(n,γ)^{37,39}Ar Reactions and Their Effect on Light Neutron-Rich Nuclide Synthesis

The ^{36}Ar(n,γ)^{37}Ar (t_{1/2}=35  d) and ^{38}Ar(n,γ)^{39}Ar (269 yr) reactions were studied for the first time with a quasi-Maxwellian (kT∼47  keV) neutron flux for Maxwellian average cross section (MACS) measurements at stellar energies. Gas samples were irradiated at the high-intensity Soreq applied research accelerator facility-liquid-lithium target neutron source and the ^{37}Ar/^{36}Ar and ^{39}Ar/^{38}Ar ratios in the activated samples were determined by accelerator mass spectrometry at the ATLAS facility (Argonne National Laboratory). The ^{37}Ar activity was also measured by low-level counting at the University of Bern. Experimental MACS of ^{36}Ar and ^{38}Ar, corrected to the standard 30 keV thermal energy, are 1.9(3) and 1.3(2) mb, respectively, differing from the theoretical and evaluated values published to date by up to an order of magnitude. The neutron-capture cross sections of ^{36,38}Ar are relevant to the stellar nucleosynthesis of light neutron-rich nuclides; the two experimental values are shown to affect the calculated mass fraction of nuclides in the region A=36-48 during the weak s process. The new production cross sections have implications also for the use of ^{37}Ar and ^{39}Ar as environmental tracers in the atmosphere and hydrosphere.

Note: Proton irradiation at kilowatt-power and neutron production from a free-surface liquid-lithium target

The free-surface Liquid-Lithium Target, recently developed at Soreq Applied Research Accelerator Facility (SARAF), was successfully used with a 1.9 MeV, 1.2 mA (2.3 kW) continuous-wave proton beam. Neutrons (~2 × 10(10) n/s having a peak energy of ~27 keV) from the (7)Li(p,n)(7)Be reaction were detected with a fission-chamber detector and by gold activation targets positioned in the forward direction. The setup is being used for nuclear astrophysics experiments to study neutron-induced reactions at stellar energies and to demonstrate the feasibility of accelerator-based boron neutron capture therapy.

Effect of secondary electrons suppression on emittance measurement of an intense, low-energy beam

Transversal emittance measurements of intense low-energy beams involve use of collimators. As most of the beam is stopped by a collimator, a question arises whether the special conditions in the vicinity of the collimator influence emittance measurement. In particular, the secondary electrons emitted from the slit surface may affect the measurement of the beam phase distribution. We have observed significant modification in the measured phase space distribution of a 5-6 mA DC proton beam at the Soreq Applied Research Accelerator Facility low-energy transport after application of a weak magnetic field in the plane of the slit collimator. The periphery region of the phase distribution was mostly affected. The overall effect on the emittance value was as large as 20%.

Use of a wire scanner for monitoring residual gas ionization in Soreq Applied Research Accelerator Facility 20 keV∕u proton∕deuteron low energy beam transport beam line

The ion source end of the Soreq Applied Research Accelerator Facility accelerator consists of a proton∕deuteron ECR ion source and a low energy beam transport (LEBT) beam line. An observed reduction of the radio frequency quadrupole transmission with increase of the LEBT current prompted additional study of the LEBT beam properties. Numerous measurements have been made with the LEBT bream profiler wire biased by a variable voltage. Current-voltage characteristics in presence of the proton beam were measured even when the wire was far out of the beam. The current-voltage characteristic in this case strongly resembles an asymmetric diodelike characteristic, which is typical of Langmuir probes monitoring plasma. The measurement of biased wire currents, outside the beam, enables us to estimate the effective charge density in vacuum.

An expanded Transactional Stress and Coping Model for siblings of children with sickle cell disease: family functioning and sibling coping, self-efficacy and perceived social support

AIM

To investigate the application of an expanded Transactional Stress and Coping Model for the psychological adjustment of non-chronically ill, African-American siblings of children with sickle cell disease (SCD).

METHODS

Ninety-seven siblings (M = 11.24 years) from 65 families who care for a child with SCD participated. Primary caregivers completed the Coping Health Inventory for Parents, the Family Relations Scale and the Child Behaviour Checklist, while siblings completed the Kidcope, the Children's Self-Efficacy for Peer Interaction Scale, and the Social Support Scale for Children.

RESULTS

Family processes were predictive of sibling adjustment, revealing that family coping, expressiveness and support improved adjustment, while family conflict predicted poor adjustment.

CONCLUSION

Findings suggest that family-centered interventions stressing family expressiveness and support, while minimizing conflict, will contribute to sibling psychological adjustment.

DNA repair, mitochondria, and neurodegeneration

Accumulation of nuclear and mitochondrial DNA damage is thought to be particularly deleterious in post-mitotic cells, which cannot be replaced through cell division. Recent experimental evidence demonstrates the importance of DNA damage responses for neuronal survival. Here, we summarize current literature on DNA damage responses in the mammalian CNS in aging and neurodegeneration. Base excision repair (BER) is the main pathway for the removal of small DNA base modifications, such as alkylation, deamination and oxidation, which are generated as by-products of normal metabolism and accumulate with age in various experimental models. Using neuronal cell cultures, human brain tissue and animal models, we and others have shown an active BER pathway functioning in the brain, both in the mitochondrial and nuclear compartments. Mitochondrial DNA repair may play a more essential role in neuronal cells because these cells depend largely on intact mitochondrial function for energy metabolism. We have characterized several BER enzymes in mammalian mitochondria and have shown that BER activities change with age in mitochondria from different brain regions. Together, the results reviewed here advocate that mitochondrial DNA damage response plays an important role in aging and in the pathogenesis of neurodegenerative diseases.

Experiments with thermalized rare isotope beams from projectile fragmentation: a precision mass measurement of the superallowed beta emitter 38Ca

The mass of the short-lived radio nuclide 38Ca (T(1/2) = 440 ms) has been measured with the 9.4-T Penning trap mass spectrometer of the Low-Energy Beam and Ion Trap Facility. A mass uncertainty of deltam = 280 eV has been achieved, corresponding to deltam/m = 8 x 10(-9). The result makes 38Ca, a superallowed beta emitter, a new candidate to test the conserved-vector-current hypothesis. The experiment is also the first demonstration that short-lived radioactive isotopes produced by projectile fragmentation of relativistic heavy-ion beams can be slowed down and prepared such that precision experiments of this kind are possible.

Revised rates for the stellar triple-α process from measurement of 12C nuclear resonances

In the centres of stars where the temperature is high enough, three alpha-particles (helium nuclei) are able to combine to form 12C because of a resonant reaction leading to a nuclear excited state. (Stars with masses greater than approximately 0.5 times that of the Sun will at some point in their lives have a central temperature high enough for this reaction to proceed.) Although the reaction rate is of critical significance for determining elemental abundances in the Universe, and for determining the size of the iron core of a star just before it goes supernova, it has hitherto been insufficiently determined. Here we report a measurement of the inverse process, where a 12C nucleus decays to three alpha-particles. We find a dominant resonance at an energy of approximately 11 MeV, but do not confirm the presence of a resonance at 9.1 MeV (ref. 3). We show that interference between two resonances has important effects on our measured spectrum. Using these data, we calculate the triple-alpha rate for temperatures from 10(7) K to 10(10) K and find significant deviations from the standard rates. Our rate below approximately 5 x 10(7) K is higher than the previous standard, implying that the critical amounts of carbon that catalysed hydrogen burning in the first stars are produced twice as fast as previously believed. At temperatures above 10(9) K, our rate is much less, which modifies predicted nucleosynthesis in supernovae.

Unambiguous identification of three beta-decaying isomers in 70Cu

Using resonant laser ionization, beta-decay studies, and for the first time mass measurements, three beta-decaying states have been unambiguously identified in 70Cu. A mass excess of -62 976.1(1.6) keV and a half-life of 44.5(2) s for the (6-) ground state have been determined. The level energies of the (3-) isomer at 101.1(3) keV with T(1/2)=33(2) s and the 1+ isomer at 242.4(3) keV with T(1/2)=6.6(2) s are confirmed by high-precision mass measurements. The low-lying levels of 70Cu populated in the decay of 70Ni and in transfer reactions compare well with large-scale shell-model calculations, and the wave functions appear to be dominated by one proton-one neutron configurations outside the closed Z=28 shell and N=40 subshell. This does not apply to the 1+ state at 1980 keV which exhibits a particular feeding and deexcitation pattern not reproduced by the shell-model calculations.

Clarification of the three-body decay of 12C (12.71 MeV)

Using beta decays of a clean source of 12N produced at the IGISOL facility, we have measured the breakup of the 12C (12.71 MeV) state into three alpha particles with a segmented particle detector setup. The high quality of the data permits solving the question of the breakup mechanism of the 12.71 MeV state, a longstanding problem in few-body nuclear physics. Among existing models, a modified sequential model fits the data best, but systematic deviations indicate that a three-body description is needed.

Precision measurement of the 7Be(p,gamma)8B cross section with an implanted 7Be target

The 7Be(p,gamma)8B reaction plays a central role in the evaluation of solar neutrino fluxes. We report on a new precision measurement of the cross section of this reaction, following our previous experiment with an implanted 7Be target, a raster-scanned beam, and the elimination of the backscattering loss. The new measurement incorporates a more abundant 7Be target and a number of improvements in design and procedure. The point at E(lab)=991 keV was measured several times under varying experimental conditions, yielding a value of S17(E(c.m.)=850 keV)=24.0+/-0.5 eV b. Measurements were carried out at lower energies as well. Because of the precise knowledge of the implanted 7Be density profile, it was possible to reconstitute both the off- and on-resonance parts of the cross section and to obtain from the entire set of measurements an extrapolated value of S17(0)=21.2+/-0.7 eV b.

Transplanted lichens in and around the Mount Carmel National Park and the Haifa Bay industrial region in Israel: physiological and chemical responses

This study investigated the impact of air pollution on the spectral reflectance of the epiphytic lichen Ramalina lacera, indicated by the normalized difference vegetation index (NDVI), on the integrity of chlorophyll, indicated by the ratio OD435 nm/OD415 nm, and on the integrity of cell membranes, indicated by electric conductivity. Data relating to physiological parameters of injury were integrated with data concerning the detrimental deposition of mineral elements. The transplanted lichen, originating in a relatively unpolluted site in Israel, was placed in 17 sites on and around the Carmel Mountain and in 2 sites in an industrial region in the Haifa Bay, northwest Israel, for a period of 10 months. The accumulated amounts of Ca, Ti, Cu, Mg, Fe, Si, Ni, Zn, V, Cr, Mn, Cl-, K, F-, Na, Ba, Sr, B, S, P, Al, PO(3-)(4), SO(2-)(4), and NO-3 were related to alterations in spectral reflectance and injury caused to chlorophyll and cell membranes. At the end of the period of exposure, the retrieved transplants from the Haifa Bay exhibited low NDVI values and low OD435 nm/OD415 nm ratios, indicating chlorophyll degradation, and high electric conductivity values, indicating damaged cell membranes. NDVI values correlated positively with OD435 nm/OD415 nm ratios and negatively with accumulated amounts of Ba, Cu, Ni, S, SO(2-)(4), V, and Zn. OD435 nm/OD415 nm ratios correlated negatively with amounts of Ba, Cu, Ni, NO(-)(3), SO(2-)(4), and V. Values obtained for electric conductivity correlated positively with amounts of B, Ba, Cl-, Cr, Cu, Na, Ni, NO(-)(3), S, and SO(2-)(4). Both elemental and ion content and the physiological status of the R. lacera transplants indicated that the greater part of the biomonitoring sites on and around the Carmel Mountain were slightly polluted or unpolluted, whereas the Haifa Bay region was rather polluted. The greater part of the Haifa Bay pollution derives from the combustion of heavy fuel oil.

Improving adherence with deferoxamine regimens for patients receiving chronic transfusion therapy

We designed a study to obtain follow-up on behavioral aspects of compliance with home deferoxamine administration, explore social factors that might influence compliance, and evaluate the effectiveness of a pilot intervention program for patients with thalassemia or sickle cell disease who were receiving chronic transfusion therapy. Thirty-one patients between the ages of 6 and 21 years and their primary caregivers were administered a 24-hour recall Interview about home care. Fifteen went on to participate in a Desferal Day Camp, which combined educational strategies with peer support. Behavioral measures of treatment adherence were similar for most patients with sickle cell disease and thalassemia. Patient compliance with days of deferoxamine administration at follow-up was associated with initial compliance, perceived support, and patient and caregiver knowledge. Increased sharing of responsibilities for home care by patients and caregivers and caregiver knowledge were associated with lower ferritin and liver iron levels. A subsample of 3 patients who were extremely noncompliant with days of deferoxamine administration was examined separately; these patients were found to be moderately compliant with the number of hours and amount of deferoxamine administered and to share fewer home care tasks with primary caregivers. Participation in Desferal Day Camp did not result in increases in knowledge or peer support, suggesting that future interventions should focus on family support and on improving self-regulatory skills. The crucial role of collaboration among patients, families, and health care providers in developing interventions to enhance adherence was emphasized.

Resource utilization associated with initial hospital stays complicated by early onset group B streptococcal disease

BACKGROUND

The epidemiology of early onset neonatal group B streptococcal (GBS) disease has changed appreciably, but there are no recent assessments of the in-hospital resource utilization it incurs.

STUDY DESIGN

We performed a retrospective cohort study of infants delivered from 1987 through 1995 at Massachusetts' largest obstetrics hospital. A matched cohort design was used to assess care occurring after transfer to another acute care hospital.

RESULTS

There were 135 cases of early onset neonatal GBS infection complicating 85,062 deliveries (1.6/1,000 births) in 9 years, with a substantial decline beginning in 1994, when maternal intrapartum chemoprophylaxis was widely introduced. Most (73%) infants had birth weights of 2500 g or more; 93% survived. Overall both the median and mean lengths of stay were 8 days longer for infants with GBS disease than for those without this infection (P < 0.001). Total hospital charges for neonates with GBS disease also were higher, with the difference in medians of $5323 and in means of $10,004 (P < 0.001). Differences were greatest among >2500-g birth weight infants; no excess was evident for infants with birth weights of < 1500 g.

CONCLUSION

There was a substantial excess length of stay and charges associated with early onset neonatal GBS disease, although this was less than previously reported.

Telephone follow-up for case finding of domestic violence in an emergency department

OBJECTIVE

To determine whether telephone follow-up of selected female patients seen in an urban ED would improve domestic violence (DV) case finding.

METHODS

A prospective, cross-sectional study was conducted on consecutive female patients between the ages of 16 and 65 years treated in an urban trauma center during July and August 1995. Record review identified those patients with conditions suggesting increased risk for DV: injury; substance abuse; complaints or diagnoses related to stress, anxiety, depression, or panic attack; or complaints of headache, nonspecific abdominal pain, generalized fatigue, or numbness lasting > 1 week. Attempts were made to telephone all patients who had high-risk presentations within 3 days of their emergency visits. Patients were contacted by a trained interviewer regarding the circumstances of their visits.

RESULTS

There were 142 (9%) high-risk presentations out of 1,500 ED visits by women. Of these high-risk visits, 68 patients denied DV, 19 patients did no speak English, 16 patients gave an incorrect telephone number, 18 patients could not be reached after 3 telephone calls, and 6 patients did not give a telephone number. Of the remaining 15 patients, 5 were diagnosed at the initial visit as having experienced DV, and 10 admitted on the follow-up call that the visit had been related to DV or emotional stress at home.

CONCLUSION

A structured interview, conducted via telephone in follow-up of released ED patients, identified an additional 10 victims out of 142 high-risk presentations and 1,500 total ED presentations. This approach is labor-intensive, with a relatively low yield. Nonetheless, prospective identification of selective high-risk cases by physicians, coupled with subsequent social service telephone contact, may be a complement in department case finding.

Incidence of sudden infant death syndrome in Olmsted County, Minnesota: 1945 through 1992

OBJECTIVE

To apply uniform diagnostic criteria for sudden infant death syndrome (SIDS) for an extended period for comparison of incidence rates from 1945 to 1992 in Olmsted County, Minnesota, to investigate the influence of a person-time or live birth denominator on the estimate of incidence, to calculate the proportionate mortality rate for SIDS over time, and to evaluate the accuracy of death certificates for case ascertainment and the role of interobserver variation in case classification.

DESIGN

We retrospectively reviewed the autopsy results and complete medical records for all infant death from 1945 through 1992 for residents of Olmsted County, Minnesota.

MATERIAL AND METHODS

Cases were identified from a computerized list of all Olmsted County deaths of infants occurring at ages 48 hours to 365 days. All resident cases were categorized as non-SIDS, possible SIDS, SIDS, or incomplete, on the basis of findings from autopsy and clinical history. Incidence rates were calculated for two different SIDS groups and with use of denominators of person-time and live births.

RESULTS

For the study period, 82 cases of SIDS were identified (97% white and 3% Asian). The mean age at death was 12.5 weeks; male infants constituted 59% of cases. No significant trend in seasonal distribution was noted; 73% of deaths occurred between midnight and noon. The incidence rate, defined as SIDS definite and possible deaths per 1,000 resident live births, increased from 0.55 in 1950 through 1953 to 1.28 in 1990 through 1992. The secular trend was best described by a linear model with constant positive slope. Similar trends were observed with other definitions of incidence. During the study period, SIDS as a percentage of total infant deaths dramatically increased, ranging from 2.5 in 1950 through 1953 to 17.9 in 1990 through 1992. The death certificate diagnosis correctly predicted 72% of SIDS cases before 1970 and 100% of cases after 1970.

CONCLUSION

Since 1945, the incidence of SIDS apparently has increased, although diagnostic transfer from other causes of death probably contributes to the observed trend. The comparison of live births versus person-time as denominators showed no significant difference in incidence rates. Interobserver reliability is modest for SIDS cases diagnosed before 1970 and may contribute to the variability in reported SIDS incidence rates.

Postpubertal disease status in diabetes and factor structure anomaly on the WISC-R

Diabetic children have been found to display an anomalous factor structure on the Wechsler Intelligence Scale for Children-Revised (WISC-R) (Holmes, Cornwell, Dunlap, Chen, & Lee, 1992). The present study sought to extend this finding with a larger cross-regional sample of children to determine which, if any, demographic or disease factor(s) might be related to the anomalous structure. Results revealed that groups of older (> = 12 years) children and those with late disease onset (> = 5 years) exhibited an anomalous four-factor structure in which the traditional Perceptual Organization factor (II) split into two factors: Picture Completion and Picture Arrangement formed a visual discrimination factor; and Block Design and Object Assembly created a spatial conceptual factor. It is postulated that diabetic performance on this visual discrimination factor may reflect mild visual neuropathies, often associated with adolescence and postpubertal disease status.

Escalating doses of carboplatin with high-dose ifosfamide using autologous bone marrow as support: a phase I study

In this phase I study, 16 adult cancer patients were treated with concurrent 4-day continuous infusions of ifosfamide at 12 g/m2 and escalating doses of carboplatin (400-1600 mg/m2) to determine the major non-haematological dose-limiting toxicity of the combination. Mesna was given by continuous infusion over 5 days for uroprotection (total dose per course = 15 g/m2). Autologous bone marrow support, which was mandated for subsequent dose levels once granulocytes remained below 500/microliters for more than 14 days in at least 2 patients entered at a given dose level, was used at dose levels above 400 mg/m2 carboplatin. Renal toxicity became dose-limiting at the maximum tolerated dose level of 1600 mg/m2 carboplatin. Temporary creatinine elevations above 2 mg/dl (median peak 2.6 mg/dl) were observed in 3 and irreversible renal toxicity occurred in 1 (peak creatinine 6.9 mg/dl, chronic creatinine 5-6 mg/dl) of the 5 patients entered at this dose level. Severe confusion and lethargy associated with rising creatinine developed in 2 patients. Two complete and four partial responses were documented in 14 heavily pretreated evaluable patients. The complete responses continue at 14+ and 20+ months in a patient with germ cell carcinoma and Ewing's sarcoma, respectively. Carboplatin appears to contribute to the renal toxicity of ifosfamide. Nevertheless, the combination of carboplatin and ifosfamide at 80% and 75% of the single-agent maximal tolerated doses respectively produced acceptable non-haematological toxicity. Further studies in the treatment of sarcoma, germ cell, ovarian and lung carcinomas with this combination are warranted.

Extrapleural pneumonectomy, chemotherapy, and radiotherapy in the treatment of diffuse malignant pleural mesothelioma

Malignant pleural mesothelioma has been considered a uniformly fatal disease associated with a median survival of 4 to 18 months. Extrapleural pneumonectomy alone has proved disappointing in the treatment of this disease, as have chemotherapy and radiotherapy. From 1980 to 1990, 31 patients with pleural mesothelioma underwent multimodality therapy that included extrapleural pneumonectomy with resection of the pericardium and diaphragm. The age of the patients was 53.4 +/- 8.6 years; 26 were male. All patients had the pathologic diagnosis reviewed before treatment. At thoracotomy six patients had residual (unresectable) gross disease, and in 23 there was histologic evidence of disease at the resection margin. The perioperative morbidity and mortality rates were 19% and 6%, respectively. The mean length of hospital stay for the 29 patients who survived the operation was 10.9 +/- 3.5 days. Postoperatively 26 patients received cyclophosphamide, doxorubicin, and cis-platinum chemotherapy with or without radiotherapy. The survival rates were 70% at 1 year and 48% at 2 years. Trends toward improved survival in the patients with complete resections approached but did not reach statistical significance. These data suggest that this multimodality protocol can be administered with acceptable morbidity and mortality. Prospective trials are justified to further clarify the role of this approach.

A phase I study of high-dose ifosfamide and escalating doses of carboplatin with autologous bone marrow support

The dose-limiting toxicity in two separate phase I trials of the high-dose single agents ifosfamide and carboplatin was renal insufficiency at 18 g/m2 and hepatic and ototoxicity at 2,400 mg/m2, respectively. In this phase I study, 16 adults were treated with ifosfamide at 75% of the single-agent maximum-tolerated dose (MTD) (12 g/m2) and escalating doses of carboplatin (400 to 1,600 mg/m2) to determine the nonhematologic dose-limiting toxicity and the maximum-tolerated dose of the combination. Both drugs as well as mesna for uroprotection were given by continuous infusion over 4 days with an additional day of mesna (total dose per course, 15 g/m2). Autologous bone marrow support was stipulated for subsequent dose levels once granulocytes remained less than 500/microL for more than 14 days in two of three to five patients entered at a given dose level. Autologous bone marrow support was used at doses above the 400 mg/m2 carboplatin dose level. At the maximum-tolerated dose level of 1,600 mg/m2 of carboplatin, renal toxicity precluded further dose escalation. Of the five patients entered at this dose level, reversible creatinine elevation greater than 2 mg/dL (median peak, 2.6 mg/dL) was observed in three patients, and irreversible renal failure occurred in an additional patient (peak creatinine, 6.9 mg/dL. Transient gross hematuria appeared more common with the combination than with ifosfamide alone. Two patients developed severe somnolence and confusion associated with a rising creatinine. There were two complete (CRs) and four partial responses (PRs) in 14 heavily pretreated assessable patients (including four partial or complete responses in eight assessable patients with advanced refractory sarcoma, and one CR in two patients with germ cell carcinoma). Carboplatin and ifosfamide appear to have overlapping renal toxicity. Nevertheless, carboplatin and ifosfamide can be combined at 80% and 75% of the single-agent maximum-tolerated doses, respectively, with acceptable nonhematologic toxicity. Ifosfamide and carboplatin are an attractive core combination for further studies in the treatment of sarcoma, germ cell, ovarian, and lung carcinomas.

High-dose thiotepa alone and in combination regimens with bone marrow support

Curative treatment regimens for leukemias, lymphomas, and testicular cancer have been based on laboratory observations of a clear relationship (generally linear-log) between increasing doses of chemotherapeutic agents and tumor cytotoxicity and on recognition of the need for combination chemotherapy to avoid the emergence of drug resistance. Chemotherapeutic agents have been selected for combinations based on cytotoxic activity, different mechanisms of action (to avoid cross-resistance), and different dose-limiting toxicities (to avoid additive toxicity). The ideal combinations use the highest tolerable doses of active non-cross-resistant agents to minimize the potential for drug resistance and achieve optimum cytotoxicity. Dose escalation is often limited by myelosuppression. Hematologic stem cell support from bone marrow or peripheral blood allows the administration of significantly higher doses of chemotherapy. In 1977, Thomas and colleagues in Seattle reported that 13 of 100 patients who underwent bone marrow transplantation for relapsed acute leukemia were disease-free 1 to 4.5 years later. Today, almost 50% of selected patients with acute myelogenous leukemia who undergo transplantation with human leukocyte antigen-matched sibling donor marrow during first remission are cured. Between 20% and 50% of lymphoma patients who undergo transplantation after failing conventional treatment have survived; those whose disease is responding to standard-dose therapy at the time of transplant have the best prognosis. Conditioning regimens that are sufficiently cytoreductive are not currently available for patients with solid tumors. The diversity of solid tumors makes it likely that a variety of regimens will be required. In a sequence of laboratory and clinical studies, we have constructed and evaluated a regimen comprising 6 g/m2 of cyclophosphamide, 500 mg/m2 of N,N',N''-triethylenethiophosphoramide (thiotepa), and 800 mg/m2 of carboplatin. The response rate in women with measurable breast cancer was 81%. While profound myelosuppression was noted, organ toxicity has been rare. This regimen, designed to exploit the principles of curative cancer chemotherapy, is associated with low morbidity and high cytoreductive efficacy. The regimen is currently being evaluated in a phase II trial in patients with previously untreated metastatic breast cancer who are responsive to conventional-dose chemotherapy. Of 29 patients entered in the study, only one has died of toxicity, confirming the low incidence of treatment-related toxicity associated with the regimen.

The structure of melittin in the form I crystals and its implication for melittin's lytic and surface activities

Melittin from bee venom is water-soluble, yet integrates into membranes and lyses cells. Each melittin chain consists of 26 amino acid residues and in aqueous salt solutions it exists as a tetramer. We have determined the molecular structure of the tetramer in two crystal forms grown from concentrated salt solutions. In both crystal forms the melittin polypeptide is a bent alpha-helical rod, with the "inner" surface largely consisting of hydrophobic sidechains and the "outer" surface consisting of hydrophilic side chains. Thus, the helix is strongly amphiphilic. In the tetramer, four such helices contribute their hydrophobic side chains to the center of the molecule. The packing of melittin tetramers is also very similar in the two crystal forms: they are packed in planar layers with the outsides forming hydrophilic surfaces and the insides (the centers of melittin tetramers) forming a hydrophobic surface. We suggest that the surface activity of melittin can be rationalized in terms of these surfaces. The lytic activity of melittin can also be interpreted in terms of the molecular structure observed in the crystals: the hydrophobic inner surface of a melittin helix may integrate into the apolar region of a bilayer with the helix axis approximately parallel to the plane of the bilayer, and with the hydrophilic surface exposed to the aqueous phase. This integration would be expected to disrupt the bilayer because of melittin helix would penetrate only a short distance into it. Additionally, the integration of melittin from one side of a bilayer would produce a surface area difference across the bilayer, perhaps leading to lysis. In this view, melittin is distinct from membrane proteins that penetrate evenly into both leaflets of a bilayer or exactly halfway through a bilayer, and hence we refer to melittin as a surface-active protein.

Clinical bioavailability evaluation of a controlled release formulation of diazepam

A controlled release formulation of diazepam was compared to equal daily dose of the trade tablet under single day and steady-state conditions. Virtually no differences were found in the mean steady-state concentrations of diazepam or its metabolites, N-desmethyldiazepam, when the subjects received the 5 mg trade table three times daily or the 15 mg controlled release formulation once daily. Similarly, there was no difference in mean diazepam or N-desmethyldiazepam plasma concentrations when single doses of the controlled release formulation were give to fed or fasted volunteers. These data indicate that the controlled release formulation produces plasma concentrations of diazepam and N-desmethyldiazepam comparable to those achieved with the same daily dose of the trade product given three times daily, suggesting that these regimens can be used interchangeably.

Multiple-dose phase I trials--normal volunteers or patients? One viewpoint

Traditionally, Phase I tolerance trials have been done with normal volunteers to establish single- and multiple-dose tolerance. We feel that the justification for doing multiple-dose tolerance studies in normals is open to question and that, in fact, more pertinent data can be generated by using the appropriate patient populations for these studies.

Pharmacokinetics of flunitrazepam following single- and multiple-dose oral administration to healthy human subjects

Healthy human subjects received single and multiple oral doses of flunitrazepam. Absorption and disposition were first order and reproducible from administration. The oral doses were virtually completely available to the liver, and elimination from the body occurred entirely via metabolism. Assuming the liver to be the sole eliminating organ, hepatic blood clearance and extraction ratio were approximately 0.235 liter/hr/kg and 0.154, respectively. Steady-state blood volume of distribution averaged 3.76 liters/kg in the single-dose studies. Terminal exponential half-lives from the single- and multiple-dose studies (different subjects) averaged 13.5 and 19.2 hr, respectively; these differences were not due to clearance changes but were entirely attributable to variations in volumes of distribution.

Keratinizing dermatoses. Combined data from four centers on short-term topical treatment with tretinoin

In four medical centers, 40 patients with keratinizing dermatoses were treated with topical tretinoin (vitamin A acid) 0.1% cream and salicylic acid 2% cream in a short-term, double-blind study. Tretinoin was the more effective treatment for several of the keratinizing dermatoses with the exception of palmar-plantar hyperkeratosis, for which it was not effective in the concentration and method of application used. The most striking clinical responses occurred in patients with lamellar ichthyosis and ichthyosis vulgaris. Local adverse reactions-chiefly pruritus, erythema, burning, excoriation, and irritation-were not severe and could be controlled by modification of the treatment regimen.

Effect of flurazepam on common clinical laboratory tests

Twenty-two clinical laboratory tests performed on blood samples from 16 normal subjects following one week of either flurazepam or placebo administered in a double-blind method showed no apparent chemical interference by flurazepam on any of the testing procedures.

The structure of form I crystals of D-ribulose-1,5-diphosphate carboxylase

Single crystals of d -ribulose-1,5-diphosphate carboxylase from tobacco leaves, Nicotiana tabacum (variety Turkish Samsun), have been examined by X-ray diffraction, electron microscopy, and optical diffraction. Twelve molecules are loosely packed into a body-centered cubic unit cell, space group 14132 with cell dimension a = 383 Å. The asymmetric unit is one quarter of a molecule, and the minimum molecular symmetry is 222. This symmetry when combined with estimates of the two subunit masses and stoichiometry is compatible with a molecular structure of the composition L8S8 (L is large subunit, S is small). If all bonds between large and small subunits are equivalent, the true molecular symmetry is 422; this symmetry is consistent with molecular images in micrographs.