Phase I Trial of Stereotactic MRI-Guided Online Adaptive Radiation Therapy (SMART) for the Treatment of Oligometastatic Ovarian Cancer

PURPOSE

Stereotactic body radiation therapy is increasingly used to treat a variety of oligometastatic histologies, but few data exist for ovarian cancer. Ablative stereotactic body radiation therapy dosing is challenging in sites like the abdomen, pelvis, and central thorax due to proximity and motion of organs at risk. A novel radiation delivery method, stereotactic magnetic-resonance-guided online-adaptive radiation therapy (SMART), may improve the therapeutic index of stereotactic body radiation therapy through enhanced soft-tissue visualization, real-time nonionizing imaging, and ability to adapt to the anatomy-of-the-day, with the goal of producing systemic-therapy-free intervals. This phase I trial assessed feasibility, safety, and dosimetric advantage of SMART to treat ovarian oligometastases.

METHODS AND MATERIALS

Ten patients with recurrent oligometastatic ovarian cancer underwent SMART for oligometastasis ablation. Initial plans prescribed 35 Gy/5 fractions with goal 95% planning target volume coverage by 95% of prescription, with dose escalation permitted, subject to strict organ-at-risk dose constraints. Daily adaptive planning was used to protect organs-at-risk and/or increase target dose. Feasibility (successful delivery of >80% of fractions in the first on-table attempt) and safety of this approach was evaluated, in addition to efficacy, survival metrics, quality-of-life, prospective timing and dosimetric outcomes.

RESULTS

Ten women with seventeen ovarian oligometastases were treated with SMART, and 100% of treatment fractions were successfully delivered. Online adaptive plans were selected at time of treatment for 58% of fractions, due to initial plan violation of organs-at-risk constraints (84% of adapted fractions) or observed opportunity for planning target volume dose escalation (16% of adapted fractions), with a median on-table time of 64 minutes. A single Grade ≥3 acute (within 6 months of SMART) treatment-related toxicity (duodenal ulcer) was observed. Local control at 3 months was 94%; median progression-free survival was 10.9 months. Median Kaplan-Meier estimated systemic-therapy-free survival after radiation completion was 11.5 months, with concomitant quality-of-life improvements.

CONCLUSIONS

SMART is feasible and safe for high-dose radiation therapy ablation of ovarian oligometastases of the abdomen, pelvis, and central thorax with minimal toxicity, high rates of local control, and prolonged systemic-therapy-free survival translating into improved quality-of-life.

Radiation therapy for vaginal and perirectal lesions in recurrent ovarian cancer

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Radiation to isolated vaginal and perirectal ovarian cancer recurrences provides effective in-field control.

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Complete response of targeted lesions after radiation was 88%.

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Radiation increased the chemotherapy-free interval without associated grade 3/4 toxicities.

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Platinum sensitivity prior to radiation may be associated with improved overall survival.

The role for localized radiation to treat ovarian cancer (OC) patients with locally recurrent vaginal/perirectal lesions remains unclear, though we hypothesize these patients may be salvaged locally and gain long-term survival benefit. We describe our institutional outcomes using intensity modulated radiation therapy (IMRT) +/- high-dose rate (HDR) brachytherapy to treat this population. Our primary objectives were to evaluate complete response rates of targeted lesions after radiation and calculate our 5-year in-field control (IFC) rate. Secondary objectives were to assess radiation-related toxicities, chemotherapy free-interval (CFI), as well as post-radiation progression-free (PFS) and overall survival (OS). PFS and OS were defined from radiation start to either progression or death/last follow-up, respectively. This was a heavily pre-treated cohort of 17 recurrent OC patients with a median follow-up of 28.4 months (range 4.5–166.4) after radiation completion. 52.9% had high-grade serous histology and 4 (23.5%) had isolated vaginal/perirectal disease. Four (23.5%) patients had in-field failures at 3.7, 11.2, 24.5, and 27.5 months after start of radiation, all treated with definitive dosing of radiation therapy. Patients who were platinum-sensitive prior to radiation had similar median PFS (6.5 vs. 13.4 months, log-rank p = 0.75), but longer OS (71.1 vs 18.8 months, log-rank p = 0.05) than their platinum-resistant counterparts. Excluding patients with low-grade histology or who were treated with palliative radiation, median CFI was 14.2 months (range 4.7 – 33.0). Radiation was well tolerated with 2 (12.0%) experiencing grade 3/4 gastrointestinal/genitourinary toxicities. In conclusion, radiation to treat locally recurrent vaginal/perirectal lesions in heavily pre-treated OC patients is safe and may effectively provide IFC.

Tumor Microenvironment as a Regulator of Radiation Therapy: New Insights into Stromal-Mediated Radioresistance

Simple Summary

Cancer is multifaceted and consists of more than just a collection of mutated cells. These cancerous cells reside along with other non-mutated cells in an extracellular matrix which together make up the tumor microenvironment or tumor stroma. The composition of the tumor microenvironment plays an integral role in cancer initiation, progression, and response to treatments. In this review, we discuss how the tumor microenvironment regulates the response and resistance to radiation therapy and what targeted agents have been used to combat stromal-mediated radiation resistance.

Abstract

A tumor is a complex “organ” composed of malignant cancer cells harboring genetic aberrations surrounded by a stroma comprised of non-malignant cells and an extracellular matrix. Considerable evidence has demonstrated that components of the genetically “normal” tumor stroma contribute to tumor progression and resistance to a wide array of treatment modalities, including radiotherapy. Cancer-associated fibroblasts can promote radioresistance through their secreted factors, contact-mediated signaling, downstream pro-survival signaling pathways, immunomodulatory effects, and cancer stem cell-generating role. The extracellular matrix can govern radiation responsiveness by influencing oxygen availability and controlling the stability and bioavailability of growth factors and cytokines. Immune status regarding the presence of pro- and anti-tumor immune cells can regulate how tumors respond to radiation therapy. Furthermore, stromal cells including endothelial cells and adipocytes can modulate radiosensitivity through their roles in angiogenesis and vasculogenesis, and their secreted adipokines, respectively. Thus, to successfully eradicate cancers, it is important to consider how tumor stroma components interact with and regulate the response to radiation. Detailed knowledge of these interactions will help build a preclinical rationale to support the use of stromal-targeting agents in combination with radiotherapy to increase radiosensitivity.

Single-Institution Phase 1/2 Prospective Clinical Trial of Single-Fraction, High-Gradient Adjuvant Partial-Breast Irradiation for Hormone Sensitive Stage 0-I Breast Cancer

PURPOSE

We sought to evaluate the feasibility and tolerability of a novel accelerated partial breast irradiation regimen delivered in a single fraction postoperatively.

METHODS AND MATERIALS

We enrolled 50 patients with low-risk, hormone-sensitive breast cancer from 2015 to 2018 on a prospective phase 1/2 trial to receive single-fraction, high-gradient partial-breast irradiation (SFHGPBI) 2 to 8 weeks after lumpectomy for node-negative, invasive, or in situ breast cancer. The high gradient was achieved by prescribing 20 Gy to the surgical bed and 5 Gy to the breast tissue within 1 cm of the surgical bed simultaneously in 1 fraction using external beam.

RESULTS

The median age was 65 (range, 52-84). Ten patients (20%) had small-volume ductal carcinoma in situ while the remainder had stage I disease. At a median follow-up of 25 months, we evaluated toxicity, patient- and physician-reported cosmesis, patient-reported quality of life (QOL), and initial tumor control. There was no Common Terminology Criteria for Adverse Events v4.0 grade 3+ toxicity. Only 34% of patients experienced grade 1 erythema. Good-to-excellent pretreatment cosmesis was present in 100% and 98% per physicians and patients, respectively, and did not change post-SFHGPBI. Quantitative cosmesis by percentage of breast retraction assessment significantly improved over time during the post-SFHGPBI period per mixed repeated measures modeling (P = .0026). QOL per European Organization for Research and Treatment of Cancer QOL Questionnaires C30 and BR-23 did not decline other than temporarily in the systemic therapy effects and hair loss domains, both of which returned to pretreatment values. There was 1 noninvasive in-breast recurrence in a separate untreated quadrant 18 months post-SFHGPBI and 1 isolated axillary recurrence 30 months post-SFHGPBI, both salvaged successfully. There were no distant recurrences or cancer-related deaths observed.

CONCLUSIONS

Accelerated partial-breast irradiation delivered in a single fraction postoperatively using external beam techniques is a novel, feasible, well-tolerated regimen. SFHGPBI does not adversely affect cosmesis or QOL as reported by both physicians and patients. Initial tumor control rates are excellent, with longer follow-up required to confirm efficacy.

Lipid peroxidation and antioxidants status in human malignant and non-malignant thyroid tumours

Introduction:

Thyroid epithelial cells produce moderate amounts of reactive oxygen species that are physiologically required for thyroid hormone synthesis. Nevertheless, when they are produced in excessive amounts, they may become toxic.

Objective:

The present study is aimed to compare the lipid peroxidation (LPO), antioxidant enzymes – superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and non-protein thiols (reduced glutathione (GSH)) in human thyroid tissues with malignant and non-malignant disorders.

Design and Methods:

The study used human thyroid tissues and blood samples from 157 women (147 diseased and 10 normal). Thyroid hormones, oxidative stress markers and antioxidants were estimated by standard methods.

Results:

LPO significantly increased in most of the papillary thyroid carcinoma (PTC: 82.9%) and follicular thyroid adenoma (FTA: 72.9%) tissues, whilst in a majority of nodular goitre (69.2%) and Hashimoto’s thyroiditis (HT: 73.7%) thyroid tissues, it remained unaltered. GSH increased in PTC (55.3%), remained unaltered in FTA (97.3%) and all other goiter samples studied. SOD increased in PTC (51.1%) and all other malignant thyroid tissues studied. CAT remained unaltered in PTC (95.7%), FTA (97.3%) and all other non-malignant samples (HT, MNG, TMNG) studied. GPx increased in PTC (63.8%), all other malignant thyroid tissues and remained unaltered in many of the FTA (91.9%) tissues and all other non-malignant samples (HT, MNG, TMNG) studied.

Conclusions:

In the case of non-malignant thyroid tumours, the oxidant–antioxidant balance was undisturbed, whilst in malignant tumours the balance was altered, and the change in r value observed in the LPO and SOD pairs between normal and PTC tissues and also in many pairs with multi-nodular goitre (MNG)/toxic MNG tissues may be used as a marker to differentiate/detect different malignant/non-malignant thyroid tumours.

Vessel generator noise as a settlement cue for marine biofouling species

Underwater noise is increasing globally, largely due to increased vessel numbers and international ocean trade. Vessels are also a major vector for translocation of non-indigenous marine species which can have serious implications for biosecurity. The possibility that underwater noise from fishing vessels may promote settlement of biofouling on hulls was investigated for the ascidian Ciona intestinalis. Spatial differences in biofouling appear to be correlated with spatial differences in the intensity and frequency of the noise emitted by the vessel's generator. This correlation was confirmed in laboratory experiments where C. intestinalis larvae showed significantly faster settlement and metamorphosis when exposed to the underwater noise produced by the vessel generator. Larval survival rates were also significantly higher in treatments exposed to vessel generator noise. Enhanced settlement attributable to vessel generator noise may indicate that vessels not only provide a suitable fouling substratum, but vessels running generators may be attracting larvae and enhancing their survival and growth.

PARP-1: Friend or Foe of DNA Damage and Repair in Tumorigenesis?

Oxidative stress induced by reactive oxygen species can result in DNA damage within cells and subsequently increase risk for carcinogenesis. This may be averted by repair of DNA damage through the base or nucleotide excision repair (BER/NER) pathways. PARP, a BER protein, is known for its role in DNA-repair. However, multiple lesions can occur within a small range of DNA, known as oxidative clustered DNA lesions (OCDLs), which are difficult to repair and may lead to the more severe DNA double-strand break (DSB). Inefficient DSB repair can then result in increased mutagenesis and neoplastic transformation. OCDLs occur more frequently within a variety of tumor tissues. Interestingly, PARP is highly expressed in several human cancers. Additionally, chronic inflammation may contribute to tumorigenesis through ROS-induced DNA damage. Furthermore, PARP can modulate inflammation through interaction with NFκB and regulating the expression of inflammatory signaling molecules. Thus, the upregulation of PARP may present a double-edged sword. PARP is needed to repair ROS-induced DNA lesions, but PARP expression may lead to increased inflammation via upregulation of NFκB signaling. Here, we discuss the role of PARP in the repair of oxidative damage versus the formation of OCDLs and speculate on the feasibility of PARP inhibition for the treatment and prevention of cancers by exploiting its role in inflammation.

Synthetic lethal interactions between EGFR and PARP inhibition in human triple negative breast cancer cells

Few therapeutic options exist for the highly aggressive triple negative breast cancers (TNBCs). In this study, we report that a contextual synthetic lethality can be achieved both in vitro and in vivo with combined EGFR and PARP inhibition with lapatinib and ABT-888, respectively. The mechanism involves a transient DNA double strand break repair deficit induced by lapatinib and subsequent activation of the intrinsic pathway of apoptosis. Further dissection of the mechanism reveals that EGFR and BRCA1 can be found in the same protein complex, which is reduced by lapatinib. Interestingly, lapatinib also increases cytosolic BRCA1 and EGFR, away from their nuclear DNA repair substrates. Taken together, these results reveal a novel regulation of homologous recombination repair involving EGFR and BRCA1 interaction and alteration of subcellular localization. Additionally, a contextual synthetic lethality may exist between combined EGFR and PARP inhibitors.

Kinomic profiling approach identifies Trk as a novel radiation modulator

BACKGROUND

Ionizing radiation treatment is used in over half of all cancer patients, thus determining the mechanisms of response or resistance is critical for the development of novel treatment approaches.

MATERIALS AND METHODS

In this report, we utilize a high-content peptide array platform that performs multiplex kinase assays with real-time kinetic readout to investigate the mechanism of radiation response in vascular endothelial cells. We applied this technology to irradiated human umbilical vein endothelial cells (HUVEC).

RESULTS

We identified 49 specific tyrosine phosphopeptides that were differentially affected by irradiation over a time course of 1h. In one example, the Tropomyosin receptor kinase (Trk) family members, TrkA and TrkB, showed transient activation between 2 and 15 min following irradiation. When we targeted TrkA and TrkB using small molecule inhibitors, HUVEC were protected from radiation damage. Conversely, stimulation of TrkA using gambogic amide promoted radiation enhancement.

CONCLUSIONS

Thus, we show that our approach not only can identify rapid changes in kinase activity but also identify novel targets such as TrkA. TrkA inhibition resulted in radioprotection that correlated with enhanced repair of radiation-induced damage while TrkA stimulation by gambogic amide produced radiation sensitization.

Androgen receptor expression in human thyroid cancer tissues: a potential mechanism underlying the gender bias in the incidence of thyroid cancers

Gender bias in the incidence of thyroid cancer is well known, however, the underlying mechanism is largely unknown. The current study determines variations in the molecular characteristics of thyroid cancers between men and women. Normal and cancerous thyroid tissues were collected from a total of 125 men and women who underwent surgical thyroidectomy. Testosterone levels in serum and thyroid cancer tissues were elevated in women while it decreased in men compared to respective control groups; whereas, ligand binding activity increased in men and decreased in women. Androgen receptor (AR) mRNA expression increased in a majority of men while it decreased in a majority of women except those with follicular thyroid carcinoma (FTC). In thyroid cancers of women, Pearson's correlation analysis showed a positive correlation of AR mRNA with AR protein, CBP and Sp1, whereas AR mRNA showed a negative correlation with p53. In case of men, AR mRNA showed a positive correlation with AR and cyclin D1 proteins in papillary thyroid carcinoma (PTC); and CBP and Sp1 in follicular thyroid adenoma (FTA), whereas AR mRNA showed a positive correlation with p53. Our study identified for the first time that AR is posttranscriptionally regulated by miR-124a in thyroid cancer tissues. Further, our in vitro studies with a PTC cell line (NPA-87-1) showed miR-124a as the potent inhibitor of AR that impairs cell proliferation even in the presence of testosterone. Thus, the current study suggests that: (i) the varying pattern of testosterone level and AR status in thyroid tissues of men and women may predispose to the gender specific incidence of thyroid tumors and (ii) miR-124a plays a significant role in determining the AR gene expression pattern and thus, androgen mediated thyroid tumor growth.

Induction of settlement in mussel (Perna canaliculus) larvae by vessel noise

Underwater sound plays an important role in the settlement behaviour of many coastal organisms. Large steel-hulled vessels are known to be a major source of underwater sound in the marine environment. The possibility that underwater sound from vessels may promote biofouling of hulls through triggering natural larval settlement cues was investigated for the mussel, Perna canaliculus. The mussel larvae showed significantly faster settlement when exposed to the underwater noise produced by a 125-m long steel-hulled passenger and freight ferry. Median time to attachment on the substrata (ie settlement) was reduced by 22% and the time taken for all experimental larvae to settle was reduced by 40% relative to a silent control. There was no difference in the survival of the mussel larvae among the various noise treatments. The decrease in settlement time of the mussel larvae appeared to correlate with the intensity of the vessel sound, suggesting that underwater sound emanating from vessels may be an important factor in exacerbating hull fouling by mussels.

Pharmacological characterization and appetite suppressive properties of BMS-193885, a novel and selective neuropeptide Y(1) receptor antagonist

Treatment of obesity is still a large unmet medical need. Neuropeptide Y is the most potent orexigenic peptide in the animal kingdom. Its five cloned G-protein couple receptors are all implicated in the regulation of energy homeostasis evidenced by overexpression or deletion of neuropeptide Y or its receptors. Neuropeptide Y most likely exerts its orexigenic activity via the neuropeptide Y(1) and neuropeptide Y(5) receptors, although the involvement of the neuropeptide Y(2) and neuropeptide Y(4) receptors are also gaining importance. The lack of potent, selective, and brain penetrable pharmacologic agents at these receptors made our understanding of the modulation of food intake by neuropeptide Y-ergic agents elusive. BMS-193885 (1,4-dihydro-[3-[[[[3-[4-(3-methoxyphenyl)-1-piperidinyl]propyl]amino] carbonyl]amino]phenyl]-2,6-dimethyl-3,5-pyridinedicarboxylic acid, dimethyl ester) is a potent and selective neuropeptide Y(1) receptor antagonist. BMS-193885 has 3.3 nM affinity at the neuropeptide Y(1) receptor, acting competitively at the neuropeptide Y binding site. BMS-193885 increased the K(d) of [(125)I]PeptideYY from 0.35 nM to 0.65 nM without changing the B(max) (0.16 pmol/mg of protein) in SK-N-MC cells that endogenously express the neuropeptide Y(1) receptor. It is also found to be a full antagonist with an apparent K(b) of 4.5 nM measured by reversal of forskolin (FK)-stimulated inhibition of cAMP production by neuropeptide Y. Pharmacological profiling showed that BMS-193885 has no appreciable affinity at the other neuropeptide Y receptors, and is also 200-fold less potent at the alpha(2) adrenergic receptor. Testing the compound in a panel of 70 G-protein coupled receptors and ion channels resulted in at least 200-fold or greater selectivity, with the exception of the sigma(1) receptor, where the selectivity was 100-fold. When administered intracerebroventricularly or directly into the paraventricular nucleus of the hypothalamus, it blocked neuropeptide Y-induced food intake in rats. Intraperitoneal administration of BMS-193885 (10 mg/kg) also reduced one-hour neuropeptide Y-induced food intake in satiated rats, as well as spontaneous overnight food consumption. Chronic administration of BMS-193885 (10 mg/kg) i.p. for 44 days significantly reduced food intake and the rate of body weight gain compared to vehicle treated control without developing tolerance or affecting water intake. These results provide supporting evidence that BMS-193885 reduces food intake and body weight via inhibition of the central neuropeptide Y(1) receptor. BMS-193885 has no significant effect of locomotor activity up to 20 mg/kg dose after 1 h of treatment. It also showed no activity in the elevated plus maze when tested after i.p. and i.c.v. administration, indicating that reduction of food intake is unrelated to anxious behavior. BMS-193885 has good systemic bioavailability and brain penetration, but lacks oral bioavailability. The compound had no serious cardiovascular adverse effect in rats and dogs up to 30 and 10 mg/kg dose, respectively, when dosed intravenously. These data demonstrate that BMS-193885 is a potent, selective, brain penetrant Y(1) receptor antagonist that reduces food intake and body weight in animal models of obesity both after acute and chronic administration. Taken together the data suggest that a potent and selective neuropeptide Y(1) receptor antagonist might be an efficacious treatment for obesity in humans.

Hydration study of homopolypeptides by (2)H NMR

Deuteron T(1) and T(2) was studied as a function of hydration in homopolyglycine (PG) and homopolyproline (PP). Water deuteron relaxation rates in PG conform to a hydration model involving two types of primary hydration sites where water is directly bonded to the polymer. Once these sites are filled, additional water only bonds to water molecules at the primary sites and in so doing affect their dynamics. PP exhibits an anomalous T(1) and T(2) hydration dependence which has been interpreted in terms of a cooperative water molecule-PP molecule helical conformational rearrangement which occurs once a certain hydration level is reached. The proposal of a water-PP structure is tested using molecular dynamics simulations.

Prefrontal membrane phospholipid metabolism of child and adolescent offspring at risk for schizophrenia or schizoaffective disorder: an in vivo 31P MRS study

In vivo (31)P magnetic resonance spectroscopy ((31)P MRS) studies have shown abnormal membrane phospholipid metabolism in the prefrontal cortex (PF) in the early course of schizophrenia. It is unclear, however, whether these alterations also represent premorbid risk indicators in schizophrenia. In this paper, we report in vivo (31)P MRS data on children and adolescents at high risk (HR) for schizophrenia. In vivo (31)P MRS studies of the PF were conducted on 16 nonpsychotic HR offspring of parents with schizophrenia or schizoaffective disorder, and 37 age-matched healthy comparison (HC) subjects. While 11 of the HR subjects had evidence of Axis I psychopathology (HR-P), five HR subjects had none (HR-NP). We quantified the freely mobile phosphomonoester (PME) and phosphodiester (PDE) levels reflecting membrane phospholipid precursors and breakdown products, respectively, and the relatively broad signal underlying PDE and PME peaks, comprised of less mobile molecules with PDE and PME moieties (eg, synaptic vesicles and phosphorylated proteins). Compared to HC subjects, HR subjects had reductions in freely mobile PME; the differences were accounted for mainly by the HR-P subjects. Additionally, HR-P subjects showed increases in the broad signal underlying the PME and PDE peaks in the PF. To conclude, these data demonstrate new evidence for decreased synthesis of membrane phospholipids and possibly altered content or the molecular environment of synaptic vesicles and/or phosphoproteins in the PF of young offspring at risk for schizophrenia. Follow-up studies are needed to examine the predictive value of these measures for future emergence of schizophrenia in at-risk individuals.

Dihydropyridine neuropeptide Y Y(1) receptor antagonists

Dihydropyridine 5a was found to be an inhibitor of neuropeptide Y(1) binding in a high throughput (125)I-PYY screening assay. Structure-activity studies around certain portions of the dihydropyridine chemotype identified BMS-193885 (6e) as a potent and selective Y(1) receptor antagonist. In a forskolin-stimulated c-AMP production assay using CHO cells expressing the human Y(1) receptor, 6e demonstrated full functional antagonism (K(b)=4.5 nM). Compound 6e inhibited NPY-induced feeding in satiated rats when dosed at 3.0 and 10.0 mg/kg (ip), and also decreased spontaneous overnight food consumption in rats at doses of 10 and 20 mg/kg (ip).

Postprocessing method to segregate and quantify the broad components underlying the phosphodiester spectral region of in vivo (31)P brain spectra

In a typical, in vivo (31)P brain spectrum, the phosphomonoester (PME) and phosphodiester (PDE) spectral region not only contains signals from freely mobile PMEs and PDEs (which are anabolic and catabolic products of membrane phospholipids) but also signals of broader underlying lineshapes from less-mobile molecules. In general, either the PME and PDE resonances are quantified as a combined value of freely mobile metabolites plus less-mobile molecules or the broader underlying signal is reduced/eliminated prior to or post data collection. In this study, a postprocessing method that segregates and quantifies the individual contributions of the freely mobile metabolites and the less-mobile molecules is introduced. To demonstrate the precision and accuracy of the method, simulated data and in vivo (31)P brain spectroscopy data of healthy individuals were quantified. The ability to segregate and quantify these various PME and PDE contributions provides additional spectral information and improves the accuracy of the interpretation of (31)P spectroscopy results. Magn Reson Med 45:390-396, 2001.

Molecular insights into neurodevelopmental and neurodegenerative diseases

Magnetic resonance spectroscopy (MRS) is a non-invasive physical technique that is routinely used to determine the quantity and structure of organic molecules in solution. Technical advances that have expanded the usefulness of this technique include: (1) high resolution MRS to identify and quantify individual molecules present in complex mixtures of tissue extracts; (2) in vivo MRS techniques to non-invasively monitor metabolites in humans; (3) structure determination of proteins of moderate size; and (4) improved structure characterization of solids and liquid crystals, such as the detection of phase changes in membranes. The focus of this review is on the first two technical advances mentioned above. The strengths of MRS as a research tool to investigate molecular alterations in disease states include ease of sample preparation, minimum sample manipulation, avoidance of the preparation of derivatives, and the ability to analyze an unfractionated sample. The strengths of MRS in the clinic are its ability to measure neuronal metabolite levels non-invasively in humans and its potential for disease diagnosis, monitoring disease progression, and assessing the efficacy of experimental therapies.

Magnetic resonance spectroscopy in schizophrenia: methodological issues and findings--part II

Magnetic resonance spectroscopy allows investigation of in vivo neurochemical pathology of schizophrenia. "First generation" studies, focusing on phosphorus and proton magnetic resonance spectroscopy, have suggested alterations in membrane phospholipid metabolism and reductions in N-acetyl aspartate in the frontal and temporal lobes. Some discrepancies remain in the literature, perhaps related to the variations in medication status and phase of illness in the patients examined, as well as in magnetic resonance spectroscopy methodology; the pathophysiologic significance of the findings also remains unclear. Technologic advances in magnetic resonance spectroscopy in recent years have expanded the potential to measure several other metabolites of interest such as the neurotransmitters glutamate and gamma-aminobutyric acid and macromolecules such as membrane phospholipids and synaptic proteins. Issues of sensitivity, specificity, measurement reliability, and functional significance of the magnetic resonance spectroscopy findings need to be further clarified. The noninvasive nature of magnetic resonance spectroscopy allows longitudinal studies of schizophrenia both in its different phases and among individuals at genetic risk for this illness. Future studies also need to address confounds of prior treatment and illness chronicity, take advantage of current pathophysiologic models of schizophrenia, and be hypothesis driven.

Magnetic resonance spectroscopy in schizophrenia: methodological issues and findings--part I

Our knowledge of the biological basis of schizophrenia has significantly increased with the contribution of in vivo proton and phosphorus magnetic resonance spectroscopy (MRS), a noninvasive tool that can assess the biochemistry from a localized region in the human body. Studies thus far suggest altered membrane phospholipid metabolism at the early stage of illness and reduced N-acetylaspartate, a measure of neuronal volume/viability in chronic schizophrenia. Inconsistencies remain in the literature, in part due to the complexities in the MRS methodology. These complexities of in vivo spectroscopy make it important to understand the issues surrounding the design of spectroscopy protocols to best address hypotheses of interest. This review addresses these issues, including 1) understanding biochemistry and the physiologic significance of metabolites; 2) the influence of acquisition parameters combined with spin-spin and spin-lattice relaxation effects on the MRS signal; 3) the composition of spectral peaks and the degree of overlapping peaks, including the broader underlying peaks; 4) factors affecting the signal-to-noise ratio; 5) the various types of localization schemes; and 6) the objectives to produce accurate and reproducible quantification results. The ability to fully exploit the potentials of in vivo spectroscopy should lead to a protocol best optimized to address the hypotheses of interest.

Metabolic alterations in postmortem Alzheimer's disease brain are exaggerated by Apo-E4

Alterations in phospholipid metabolites are a characteristic abnormality of Alzheimer's disease (AD). Many of these alterations have been demonstrated by magnetic resonance spectroscopy (MRS) studies of postmortem tissue. Phosphodiesters appear to be elevated late in the disease and phosphomonoesters appear to be elevated early in the disease and then decrease. Second to aging, the most robust risk factor for AD identified to date is the presence of the E4 allele of apolipoprotein-E (Apo-E). Because apolipoproteins are intimately involved in lipid metabolism, this study was performed to determine if the presence of the Apo-E4 allele affects the abnormalities in phospholipid metabolites in AD brain. Perchloric acid extracts from 12 Apo-E 3/3, 31 3/4, 6 4/4 AD brains and 5 Apo-E 3/3 control brains were studied by both proton magnetic resonance spectroscopy and phosphorus-31 magnetic resonance spectroscopy. When the E4-positive AD samples were compared with the 3/3 AD samples, an exaggeration in both phosphomonoester and phosphodiester abnormalities was observed. The decrease in N-acetyl-L-aspartate (NAA) was also exaggerated. These results suggest membrane phospholipid metabolite alterations observed in AD are more severe in the presence of the Apo-E4 allele.

Proton magnetic resonance spectroscopic imaging in patients with extratemporal epilepsy

PURPOSE

Reduced levels of N-acetylaspartate (NAA) in temporal lobes responsible for temporal lobe epilepsy have been observed consistently in proton magnetic resonance spectroscopy (MRS) studies.

METHODS

We investigated the potential of proton MRS to detect low NAA outside of the temporal lobes in patients with non-lesional partial extratemporal epilepsy. Proton MR spectroscopic imaging (MRSI) data of both frontal lobes and central/postcentral regions were obtained in 20 such patients and 16 normal control subjects. The epileptogenic region was determined by an extensive clinical-EEG investigation, including the recording of habitual seizures in each patient, and intracranial EEG recordings in 10 patients.

RESULTS

The relative NAA resonance intensities (i.e., NAA/phosphocreatine plus creatine (CR(t)), NAA/choline-containing metabolites (Cho(t)) and NAA/Cr(t) + Cho(t)), were all significantly reduced throughout the spectroscopic image as compared with that of the controls. Furthermore, reduction of the NAA ratios was greater in the epileptogenic region as compared with the nonepileptogenic regions, on EEG investigation.

CONCLUSIONS

In vivo proton MRSI of patients with nonlesional partial extratemporal epilepsy detected evidence of widespread neuronal damage or dysfunction that was greatest in the region of seizure focus.

Magnetic resonance spectroscopic changes in Alzheimer's disease

In vitro and in vivo 31P magnetic resonance (MR) spectroscopy studies of Alzheimer's disease (AD) brain have revealed alterations in membrane phospholipid metabolism and high-energy phosphate metabolism. Mildly demented AD patients compared with control subjects have increased levels of phosphomonoesters, decreased levels of phosphocreatine and probably adenosine diphosphate and an increased oxidative metabolic rate. As the dementia worsens, levels of phosphomonoesters decrease and levels of phosphocreatine and adenosine di-phosphate increase. The changes in oxidative metabolic rate suggest that the AD brain is under energetic stress. The phosphomonoester findings support our in vitro findings and implicate basic defects in membrane metabolism in AD brain. MR spectroscopy provides new diagnostic insights and a noninvasive method to follow the progression of the disease and the metabolic response to therapeutic interventions.

Aggregation of beta-amyloid peptide is promoted by membrane phospholipid metabolites elevated in Alzheimer's disease brain

Increased amounts of beta-amyloid (A beta) peptide deposits are found in Alzheimer's disease brain. These amyloid deposits have been implicated in the pathophysiology of this common dementing illness. A beta peptides have been shown to be toxic to neurons in cell culture, and this toxicity is critically dependent on the aggregation of the peptide into cross-beta-pleated sheet fibrils. Also, in vivo and postmortem NMR studies have shown changes in certain brain membrane phospholipid metabolites in normal aging and more extensive alterations in patients with Alzheimer's disease. The finding that membrane phospholipids affect the aggregation of A beta suggests that the abnormalities in membrane metabolism found in Alzheimer's disease could affect the deposition of A beta in vivo. Therefore, we examined the effect of membrane phospholipid metabolites that are altered in Alzheimer's disease brain on the aggregation of A beta(1-40) using a light scattering method. Certain metabolites (glycerophosphocholine, glycerophosphoethanolamine, and alpha-glycerophosphate) augment the aggregation of A beta. Other membrane phospholipid metabolites (phosphocholine, phosphoethanolamine, and inositol-1-phosphate) have no effect. We conclude that increased membrane phospholipid metabolite concentrations may play a role in the deposition of A beta seen in normal aging and the even greater deposition of A beta observed in Alzheimer's disease.

Magnetic resonance imaging volumetric and phosphorus 31 magnetic resonance spectroscopy measurements in schizophrenia

The purpose of this study was to examine the relationship between phosphorus magnetic resonance spectroscopy (31P MRS) parameters and left prefrontal volumes in both patients with schizophrenia and healthy subjects. 31P MRS parameters and magnetic resonance imaging (MRI) volumetric data were collected in the left prefrontal region in 10 patients with schizophrenia and 10 healthy subjects of comparable age, handedness, sex, educational level, and parental educational level. No correlations were found between any MRS parameter and grey matter volumes in the combined subjects. Phosphomonoester (PME) and grey matter volumes, however, were both correlated negatively with age. PMEs were found to be decreased, and calculated intracellular magnesium ([Mg2+]intra) was found to be increased in the patients with schizophrenia compared with healthy subjects after adjusting for left prefrontal grey and white matter, total brain volume, and age. These findings suggest that cortical grey and white manner volumes are not directly related to PME and [Mg2+]intra abnormalities in schizophrenia patients.

Proton magnetic resonance spectroscopic imaging for discrimination of absence and complex partial seizures

We performed proton magnetic resonance spectroscopic imaging of the temporal lobes between, during, and soon after nonconvulsive seizures in 20 patients with documented temporal lobe epilepsy, 5 patients with primary generalized epilepsy, and 2 patients with secondary generalized epilepsy. Our objective was to determine whether there were metabolic changes observable by magnetic resonance spectroscopic imaging during seizures and whether these changes were specific for focal or generalized nonconvulsive seizures. We found a significant increase in lactate to creatine plus phosphocreatine (lactate/creatine) values, reflecting an imbalance in energy supply and demand or an adaptation in response to ictal neuronal discharges, during and soon after complex partial seizures, but not during or soon after absence seizures associated with generalized epilepsy. In patients with temporal lobe epilepsy, the N-acetylaspartate resonance relative to creatine plus phosphocreatine was low in one or both temporal lobes, indicating neuronal loss or damage. This was not observed in patients with primary generalized epilepsy. The regions with abnormal lactate/creatine and N-acetylaspartate/creatine values corresponded to the epileptogenic focus as defined by clinical-electroencephalographic investigation. There was no change in the N-acetylaspartate/creatine values in the temporal lobes between the interictal, ictal, or postictal states. We conclude that (1) partial seizures are associated with abnormally high lactate levels, but absence seizures are not, and (2) no short-term changes of N-acetylaspartate occur during or soon after complex partial seizures or absence seizures. These findings may be related to the lack of postictal confusion in patients with absence seizures, as well as with the more benign course of primary generalized epilepsy with nonconvulsive attacks.

An in vivo proton magnetic resonance spectroscopy study of schizophrenia patients

The level of the 1H metabolites in the left dorsolateral prefrontal region of schizophrenia patients at different stages of illness were measured in vivo using a short echo time spectroscopy technique. During both the early onset and chronic stages, normal N-acetylaspartate levels were observed, which suggests that these patients had no significant neuronal cell damage and/or loss. The in vivo measurements of glutamate in the first-episode, drugnaive patients failed to provide convincing evidence for the involvement of the glutamatergic system in the dorsolateral prefrontal region. Significant differences in the glutamine levels were observed in the acutely medicated and chronic patients; however, the interpretation of these differences requires further study.

The use of a priori knowledge to quantify short echo in vivo 1H MR spectra

In vivo 1H MR spectra of the prefrontal cortex acquired with the stimulated echo acquisition mode (STEAM) TE = 20 ms sequence were quantified to determine relative levels of cerebral metabolites. A priori knowledge of spectra from individual metabolites in aqueous solution was incorporated into a frequency domain quantification technique. The accuracy and precision of modeling these metabolites were investigated with simulated spectra of varying signal-to-noise ratios (SNRs) and relative metabolite levels. The efficacy of modeling in vivo data was tested by quantifying 10 repeated measures of two consecutively acquired in vivo spectra (an 8-cm3 volume of interest (VOI) and a 4-cm3 VOI positioned within the 8-cm3 VOI) on the same normal subject. The differences in levels of glutamate (Glu), phosphocreatine plus creatine (PCr+Cr) and choline-containing compounds (Cho(t)) between spectra from the 8- and 4-cm3 VOIs corresponded with the expected differences observed in the proportions of gray matter within the VOIs (estimated from 1H images). Correcting for the T1 and T2 relaxation, the estimated concentrations of N-acetylaspartate, PCr+Cr, Cho(t), Glu, and glutamine were consistent with previous in vivo and in vitro reports.

An in vivo study of the prefrontal cortex of schizophrenic patients at different stages of illness via phosphorus magnetic resonance spectroscopy

BACKGROUND

In this study, phospholipid metabolism of cell membranes, high-energy phosphate metabolism, and intracellular free magnesium concentration in the prefrontal cortex of first-episode drug-naive schizophrenic patients and medicated schizophrenic patients at different stages of illness were compared with those of controls.

METHODS

Localized in vivo phosphorus 31 magnetic resonance spectra of the left dorsolateral prefrontal cortex of 11 drug-native, eight newly diagnosed medicated, and 10 chronic medicated patients with schizophrenia were compared with controls of similar gender, education, parental education, and handedness.

RESULTS

Significantly decreased levels of phosphomonoesters in drug-native, newly diagnosed medicated, and chronic medicated patients and significantly increased levels of phosphodiesters in drug-native patients were observed when compared with controls. There were no significant differences in the levels of high-energy phosphate metabolites between the groups except for a significant decrease in the inorganic orthophosphate levels of newly diagnosed medicated patients. A significant increase in the intracellular free magnesium concentration was observed in drug-naive, newly diagnosed medicated, and chronic medicated patients compared with controls. There were no correlations between the patients' negative and positive symptoms and the observed phosphorus-containing metabolites.

CONCLUSIONS

A reduction in precursors of membrane phospholipid are observed during the early and chronic stages of the schizophrenia illness, and breakdown products of membrane phospholipids are increased at the early stage of illness before medication treatment.

Membrane phospholipid metabolism and schizophrenia: an in vivo 31P-MR spectroscopy study

Membrane phospholipid metabolism was studied with 31P magnetic resonance spectroscopy in the left dorsal prefrontal cortex of 19 male, medicated, schizophrenic patients and compared to 18 normal male controls matched in age, education and parental education level. The schizophrenic patients had significantly decreased phosphomonoester levels (PMEs, metabolites predominantly involved in the synthesis of membrane phospholipids). Phosphodiester levels (PDEs, breakdown products of membrane phospholipids) were not statistically different in schizophrenic patients compared to controls. However, a significant increase in the PDE levels was observed in the newly diagnosed patient subgroup. This observed pattern of the PMEs and PDEs would be consistent with the presence of an abnormal neurodevelopment early in the illness of schizophrenia.

Protection from radiation-induced damage to spermatogenesis in the androgen pretreated rat

Protection of spermatogenesis from radiation-induced damage has been investigated in the adult Wistar rat. Silastic tubing containing either cholesterol or testosterone was implanted subcutaneously 7 weeks before 4 equal daily fractions of either 1, 1.5, 2, and 2.5 Gy of 230 kVp X-rays locally to the testes. Implants were removed on the day following the last fraction and 8 weeks after irradiation 88.6%, 83.8%, 63.6% and 28.9% tubule cross-sections respectively were found regenerating in rats pretreated with testosterone. In contrast, 68.45%, 58.6%, 38.2% and 17.3% tubule cross-sections regenerating were obtained in rats pretreated with cholesterol. Changes in testis weight however were found to show the reverse trend (i.e. a greater weight loss was observed following androgen pretreatment). These results show that protection of spermatogenesis from fractionated irradiation may be achieved in rat testis by androgen pretreatment.

Comparative effects of X irradiation on the testes of adult Sprague-Dawley and Wistar rats

The response of the testes of two strains of adult rats (Sprague-Dawley and Wistar) to graded single doses and split doses of 230 kVp X rays has been investigated. A marked difference was noted between the strains in the response of the clonogenic spermatogonia to irradiation, as measured histologically by the repopulation index. Single-dose response curves derived for these cells in the Sprague-Dawley strain had a much larger shoulder (up to about 4-5 Gy) than for the Wistar (less than 2 Gy). Split-dose studies revealed that this difference may partly be explained by a greater repair capacity in the cells of the Sprague-Dawley strain. Changes in serum FSH concentrations mirrored the changes in clonogenic spermatogonial survival following split doses of radiation.

The response of murine stem spermatogonia to radiation combined with 3-aminobenzamide

The influence of 3-aminobenzamide (3-AB) on the radiation response of the stem spermatogonia of the CBA mouse has been investigated. Doses of 3-AB from 66 to 450 mg/kg, administered 1 h before irradiation, significantly enhanced stem-cell killing. Enhancement was observed when 3-AB (450 mg/kg) was given up to 5 h before, but not if administered after, irradiation. When radiation was delivered at a lower dose rate (5 cGy/min compared to 180 cGy/min) significant dose sparing was achieved for radiation alone. Pretreatment with 3-AB resulted in slightly less enhancement at the low dose rate than at the high. Split-dose studies (9 Gy total dose) with radiation alone resulted in a recovery ratio of 1.4-1.5. Administration of 3-AB before the first dose resulted in a similar recovery ratio, but if given immediately after the first dose the ratio was smaller. Pretreatment of mice with the radiosensitizer RSU-1069 indicated that at least some of the stem cells were radiobiologically hypoxic. We suggest therefore that the enhancement of spermatogonial stem-cell killing by 3-AB is not entirely due to inhibition of repair processes but may also involve modification of the oxygen status of the testis.

Time dependence for the protective effect of androgen from procarbazine-induced damage to rat spermatogenesis

The protective effects of androgen pretreatment on the procarbazine-induced killing of spermatogonial stem cells in Wistar rats have been investigated. Using testosterone-filled Silastic implants (200 mm2) the degree of protection from four weekly doses of procarbazine (100 mg/kg) was found to be dependent upon the androgen pretreatment time interval as assessed by quantitative histology. No protective effect was seen until rats had received 4 wk of pretreatment with androgen, whereafter protection increased to a maximum (about 20 to 30% of tubule cross-sections exhibiting recovery) after 8 to 12 wk of pretreatment. In contrast, the same level of maximal protection could be obtained by 6 wk of pretreatment using testosterone enanthate, suggesting that differences in protection may be achieved using different modes of androgen administration.

Subarachnoid injection as a complication of retrobulbar anesthesia

We studied eight cases of apparent subarachnoid injection of local anesthetic through the optic nerve sheath and subsequent spread to the parabrainstem cisterns and the contralateral optic nerve sheath. The patients all experienced bilateral decrease in vision and ophthalmoplegia, and variable degrees of central nervous system symptoms and respiratory depression. The complications occurred with a variety of local anesthetic agents and with sharp disposable needles in six of the eight cases. These cases demonstrated the spectrum of signs and symptoms that may follow optic nerve sheath injection of local anesthetic agents.

Attempted protection of spermatogenesis from single doses of gamma-irradiation in the androgen pretreated rat

Spermatogenic stem-cell survival after gamma-irradiation has been investigated in the adult Wistar rat. Single doses of 4.5 and 9 Gy gamma-rays were administered to the testes of rats who received arachis oil (0.1 ml/100 g body weight) or testosterone enanthate (240 micrograms/100 g body weight) subcutaneously three times weekly for 6 weeks prior to radiation and during the week in which the radiations were given. A mean percentage of regenerating seminiferous tubule cross-sections of 32.45% and 7.26% was found in the testes of androgen-pretreated rats at 8 weeks after 4.5 and 9 Gy, respectively. Similar values (33.4% and 6.2%) were obtained in arachis oil-pretreated controls. We therefore conclude that protection of rat spermatogenesis from single doses of gamma-rays cannot be achieved by androgen pretreatment.

Behavioral studies with anxiolytic drugs. II. Interactions of zopiclone with ethyl-beta-carboline-3-carboxylate and Ro 15-1788 in squirrel monkeys

The effects of zopiclone (0.1-100 mg/kg) were studied alone and in combination with the benzodiazepine receptor antagonist Ro 15-1788 and the inverse agonist ethyl-beta-carboline-3-carboxylate (beta-CCE). Under one procedure, food-maintained responding of squirrel monkeys was punished during one component of a multiple schedule. Each 30th response during both components produced food and, during the punishment component, also produced electric shock. Intermediate doses of zopiclone (0.3-30 mg/kg) did not affect or decreased unpunished responding and produced large increases in punished responding; higher zopiclone doses decreased responding under both conditions. beta-CCE (0.1-3 mg/kg) reversed both the rate-increasing and the rate-decreasing effects of zopiclone under each condition, producing a dose-dependent shift to the right of the zopiclone dose-effect curves. All doses of beta-CCE higher than 0.1 mg/kg decreased responding when given alone. Ro 15-1788 (0.1 or 1 mg/kg), which had no effect on punished or unpunished responding, reversed both the rate-increasing and the rate-decreasing effects of zopiclone. Under a second procedure, zopiclone increased responding of squirrel monkeys maintained by food under a 5-min fixed-interval schedule at doses that did not affect or decreased responding comparably maintained in an alternate component by response-produced electric shock. These effects were also reversed by both Ro 15-1788 and beta-CCE. When administered alone, beta-CCE produced effects opposite those of zopiclone and the benzodiazepines by decreasing responding maintained by food and increasing shock-maintained responding.(ABSTRACT TRUNCATED AT 250 WORDS)

Testicular function in adult rats treated with the alkylating agent chlorambucil

The effects of multiple treatments with the alkylating agent chlorambucil on testicular function in the adult Wistar rat were evaluated. Weekly treatment with doses of 2.5, 5, or 10 mg/kg produced no effect either on spermatogenesis or Leydig cell function. In contrast, doses of 8 or 10 mg/kg administered twice weekly induced damage to both spermatogenesis and probably the Leydig cells. A dose-dependent decrease in spermatogonial stem-cell survival was observed with these two regimens, as assessed by counts of repopulating tubule cross sections. Although serum testosterone remained unchanged, possible Leydig cell damage was indicated by an approximate twofold increase in serum LH following treatment with either 8 or 10 mg/kg of chlorambucil twice weekly. The present results demonstrate that multiple treatments with cytotoxic drugs can be used to model the testicular damage observed in man.

Ro 15-1788 and beta-CCE selectively eliminate diazepam-induced feeding in the rabbit

Food intake was monitored in three female and one male adult rabbits following the administration of three drugs known to result in feeding increases in other species. The drugs, diazepam (1.0 mg/kg), cyproheptadine (0.03 mg/kg) and chlorpromazine (1.0 mg/kg) all produced large increases in food intake; of these, only the effect of diazepam, a benzodiazepine, was reversed by doses of the benzodiazepine antagonists Ro 15-1788 (0.3 mg/kg) and Ethyl beta-carboxylate (beta-CCE) (1.0 mg/kg) which, when given alone, did not affect feeding. The results support evidence suggesting that Ro 15-1788 and beta-CCE are specific antagonists of the benzodiazepine receptor and of their effects on a wide range of behaviors.

Characterization of an aerosol sample from the auxiliary building of the Three Mile Island reactor

Analyses for radioisotopic composition and dissolution characteristics were performed on an aerosol filter sample collected for a week by an air sampler located in the auxiliary building of the Three Mile Island nuclear reactor. The major radioisotopes found on the filter were 89Sr, 90Sr, 134Cs and 137Cs. Greater than 90% of both 89-90Sr and 134-137Cs dissolved within 48 hr in an in vitro test system. Scanning electron microscopic analyses showed the presence of respirable size particles as well as larger particles ranging up to 10 micron in diameter. The major matrix components were Fe, Ca, S, Mg, Al and Si. Although the radionuclides were present in a heterogeneous matrix, they were in a soluble form. This information enables a better evaluation of bioassay data and predictions of dose distribution resulting from an inhalation exposure to this aerosol. Further, the combination of techniques used in this study may be applicable to the characterization of other aerosols of unknown composition.

Prior behavioral experience can reverse the effects of morphine

Morphine administration typically decreases responding of squirrel monkeys trained to avoid electric shock. However, the rate-decreasing effects of morphine on avoidance responding were reversed after either concurrent or prior exposure to a condition in which responding was maintained by shock presentation. These findings demonstrate that behavioral experience can play a significant role in determining the behavioral effects of drugs and that specific types of environmental conditions can completely reverse the usual effects those drugs have on behavior.

Distribution, retention and dosimetry of plutonium and americium in the rat, dog and monkey after inhalation of an industrial-mixed uranium and plutonium oxide aerosol

This study provides information on patterns of radiation dose in laboratory animals after inhalation exposure to an aerosol of one form of mixed uranium and plutonium oxide. The aerosol contained a mixture of UO2 and 750 degrees C heat-treated PuO2 obtained from the ball milling operation in a mixed-oxide fuel fabrication process. Americium-241 from the decay of 241Pu was also present in the PuO2 matrix. Fischer-344 rats, Beagle dogs, and Cynomolgus and Rhesus monkeys inhaled aerosols re-generated from dry mixed oxide powders with particle size distribution characteristics similar to those observed in samples collected at the industrial site. Clearance from the lung and distribution in other tissues of the plutonium from this UO2 + PuO2 admixture was similar to what has been observed for PuO2 from laboratory-produced aerosols. The UO2-PuO2 aerosol was relatively insoluble in the lungs of all species. Monkeys and rats cleared plutonium and americium from their lungs faster than dogs. Very little plutonium or americium translocated within the first 2 yr after exposure to tissues other than tracheobronchial lymph nodes. The greater accumulation of plutonium and americium in the tracheobronchial lymph nodes of dogs as compared to monkeys and rats combined with the more rapid initial clearance of these radionuclides from the lungs of rats and monkeys suggests that errors could result from using data from a single animal species to estimate risk to humans from inhalation of these industrial aerosols.

Effects of chlorpromazine and d-amphetamine on schedule-controlled and schedule-related behavior of rabbits

A lever-lifting response by Dutch Belted and New Zealand White rabbits was maintained in water-deprived animals by 0.26% saccharin solution and in food-deprived animals by food pellets under a multiple 3-min fixed-interval (FI) 30-response fixed-ratio (FR) schedule. Rabbits responding for the saccharin solution had food freely available during the session and in the home cage, whereas those responding for pellets had water continuously available during the session as well as in the home cage. Under nondrug conditions the FR and FI schedules controlled different rates and patterns of responding in the rabbit that were characteristic of those found with other species. In addition, eating or drinking occurred during the initial portion of the FI under the saccharin solution and initial food presentation schedules, respectively. Doses of d-amphetamine (0.1--10.0 mg/kg) increased responding under the FI and FR schedules of food delivery, but increased only FI responding maintained by the saccharin solution. Doses of 3.0--10.0 mg/kg d-amphetamine produced extremely high (300--800% of control) rates of stereotyped perseverative level responding. Schedule-related eating or drinking were unaffected or decreased at doses of d-amphetamine that increased schedule-controlled responding. Chlorpromazine (0.03--0.3 mg/kg) increased FI responding maintained both by saccharin and food, whereas FR responding generally was unaffected at these dose levels; eating but not drinking was increased with chlorpromazine. Since the behavioral effects of drugs such as amphetamine and chlorpromazine differ somewhat in the rabbit from those found with other typically studied nonhuman mammals, further studies with the rabbit may yield useful information for comparative behavioral pharmacology.

The CT-topography of retrobulbar anesthesia. Anatomic-clinical correlation of complications and suggestion of a modified technique

The anatomic relationship of an injection needle as traditionally placed in retrobulbar anesthesia to optic nerve, orbital vessels and eye muscles is demonstrated by computed tomography. The clinical complications of retrobulbar injections are reviewed and correlated to the orbital topography in different positions of gaze, as analyzed in anatomic sections and CT images. The results indicate that with the transitional technique of retrobulbar injection the most important orbital structures are in the immediate neighbourhood of the needle. A different injection technique is discussed.

Effects of ethanol on multiple fixed-interval fixed-ratio schedule performances: dynamic interactions at different fixed-ratio values

Key pecking by three pigeons was maintained under a multiple fixed-interval fixed-ratio schedule of food presentation. The fixed-interval value remained at 3 minutes, while the fixed-ratio size was increased systematically in 30-response increments from 30 to either 120 (two pigeons) or 150 (one pigeon). At least two lower fixed-ratio values were also redetermined. The effects of ethanol (5 to 2.5 g/kg) were assessed at each of the different schedule parameters. Both overall and running response rates under the fixed-ratio schedule decreased with increases in the size of the fixed-ratio schedule; pause duration under the fixed-ratio schedule was directly related to increases in fixed-ratio size. Overall and running rates of responding under the fixed-interval schedule changed little with increases in the size of the fixed-ratio schedule. Despite the relative invariance of fixed-interval responding across the different fixed-ratio values, the effects of ethanol on responding under the fixed-interval schedule differed depending on the size of the fixed-ratio schedule. Greater increases occurred in both overall and in lower local rates of responding under the fixed-interval schedule when the fixed-ratio value was 120 or 150. The effects of ethanol on responding under the fixed-ratio schedule also depended on the size of the fixed ratio. Increases in responding under the fixed-ratio schedule were typically greater at the higher fixed-ratio values where response rates were lower. When the effects of ethanol were redetermined at the lower fixed-ratio parameter values, rates and patterns of responding were comparable to those obtained initially. However, the dose-effect curves for responding under both fixed-ratio and fixed-interval schedules were shifted up and to the right of those determined during the ascending series. The effects of ethanol can depend on rate or responding, behavioral history, and the context in which behavior occurs.