Characterizing prostate cancer risk through multi-ancestry genome-wide discovery of 187 novel risk variants

The transferability and clinical value of genetic risk scores (GRSs) across populations remain limited due to an imbalance in genetic studies across ancestrally diverse populations. Here we conducted a multi-ancestry genome-wide association study of 156,319 prostate cancer cases and 788,443 controls of European, African, Asian and Hispanic men, reflecting a 57% increase in the number of non-European cases over previous prostate cancer genome-wide association studies. We identified 187 novel risk variants for prostate cancer, increasing the total number of risk variants to 451. An externally replicated multi-ancestry GRS was associated with risk that ranged from 1.8 (per standard deviation) in African ancestry men to 2.2 in European ancestry men. The GRS was associated with a greater risk of aggressive versus non-aggressive disease in men of African ancestry (P = 0.03). Our study presents novel prostate cancer susceptibility loci and a GRS with effective risk stratification across ancestry groups.

HIV Symptom Clusters are Similar Using the Dimensions of Symptom Occurrence and Distress

CONTEXT

People living with HIV infection (PLWH) in the United States continue to experience a high symptom burden despite improvements in antiretroviral therapy.

OBJECTIVES

The purpose of this study was to determine if the number and types of symptom clusters differed based on whether symptom occurrence rates or distress ratings were used to create the clusters.

METHODS

Data from 2,000 patients with complete symptom occurrence rates and distress scores on the 20-item HIV Symptom Index from their first ambulatory clinic visit at one of six national HIV centers of excellence in the Center for AIDS Research Network of Integrated Clinical Systems were used in these analyses. Exploratory factor analysis was used to create the symptom clusters.

RESULTS

The same four symptom clusters (i.e., gastrointestinal, psychological, pain, body image) were identified using occurrence rates and distress ratings. For both dimensions of the symptom experience, the psychological, pain, and body image clusters each had the same symptoms. For the gastrointestinal cluster, four symptoms loaded on the occurrence dimension and six symptoms loaded on the distress dimension.

CONCLUSION

The number and types of symptom clusters were relatively similar across the occurrence and distress dimensions of the symptom experience. Symptom clusters in PLWH may provide insights into the development of targeted interventions for multiple co-occurring symptoms.

Testing for non-random mating: evidence for ancestry-related assortative mating in the Framingham heart study

Population stratification leads to a predictable phenomenon-a reduction in the number of heterozygotes compared to that calculated assuming Hardy-Weinberg Equilibrium (HWE). We show that population stratification results in another phenomenon-an excess in the proportion of spouse-pairs with the same genotypes at all ancestrally informative markers, resulting in ancestrally related positive assortative mating. We use principal components analysis to show that there is evidence of population stratification within the Framingham Heart Study, and show that the first principal component correlates with a North-South European cline. We then show that the first principal component is highly correlated between spouses (r = 0.58, p = 0.0013), demonstrating that there is ancestrally related positive assortative mating among the Framingham Caucasian population. We also show that the single nucleotide polymorphisms loading most heavily on the first principal component show an excess of homozygotes within the spouses, consistent with similar ancestry-related assortative mating in the previous generation. This nonrandom mating likely affects genetic structure seen more generally in the North American population of European descent today, and decreases the rate of decay of linkage disequilibrium for ancestrally informative markers.

Synthesis of vinyl-functionalized oxazoles by olefin cross-metathesis

A ruthenium-based catalyzed olefin cross-methathesis reaction involving 2- and 4-vinyl-functionalized oxazoles was developed. A wide range of olefinic partners was coupled in good to excellent yields and high stereoselectivities under mild conditions. This methodology offers new opportunities for the synthesis of a plethora of biologically active natural products.

Gastrin releasing peptide (GRP) receptor targeted radiopharmaceuticals: a concise update

The gastrin releasing peptide (GRP) receptor is becoming an increasingly attractive target for development of new radiolabeled peptides with diagnostic and therapeutic potential. The attractiveness of the GRP receptor as a target is based upon the functional expression of GRP receptors in several tumors of neuroendocrine origin including prostate, breast, and small cell lung cancer. This concise review outlines some of the efforts currently underway to develop new GRP receptor specific radiopharmaceuticals by employing a variety of radiometal chelation systems.

Syntheses, in vitro and in vivo characterization of a 99mTc-(I)-tricarbonyl-benzylamino-dihydroxymethyl phosphine (NP(2)) chelate

Studies were performed to study the complexation chemistry of 99mTc(CO)(+)(3) with a new tridentate amino-dihydroxymethyl phosphine (NP(2)) ligand with the 99mTc(CO)(3)(OH(2))(+)(3) synthon at tracer levels. A single, well-defined 99mTc(CO)(3)NP(2) complex is formed at pH 7.5 within 10 min at 60 degrees C that exhibits high in vitro and in vivo stability.

Synthesis and characterization of (99m)Tc- and (188)Re-complexes with a diamido-dihydroxymethylenephosphine-based bifunctional chelating agent (N(2)P(2)-BFCA)

A diamido-dihydroxymethylenephosphine (N(2)P(2)) bifunction chelating agent (BFCA) was shown to form well-defined (99m)Tc- and (188)Re-chelate structures. The 4, 4-bis [bis-hydroxymethyl-phosphonyl-propylcarbonmoyl]-butyric acid bifunctional chelating agent (N(2)P(2)-BFCA) formed stable complexes with (99m)Tc and (188)Re in >95% yield with high radiochemical purity (RCP). The biodistribution of the (99m)Tc- and (188)Re-N(2)P(2)-BFCAs after intravenous injection studied in normal mice showed the activity was excreted primarily via renal-urinary pathway indicating their use for labeling peptides with (99m)Tc and (188)Re.

Evaluation of an (111)In-DOTA-rhenium cyclized alpha-MSH analog: a novel cyclic-peptide analog with improved tumor-targeting properties

The aim of this study was to examine the effect of rhenium-mediated peptide cyclization on melanoma targeting, biodistribution, and clearance kinetics of the alpha-melanocyte-stimulating hormone (alpha-MSH) analog 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) coupled ReO-cyclized [Cys(3,4,10),D-Phe(7)]alpha-MSH(3-13) (DOTA-ReCCMSH).

METHODS

DOTA-ReCCMSH was compared with its reduced nonmetalated linear homolog, DOTA-CCMSH, and an analog in which rhenium cyclization was replaced by disulfide bond cyclization, DOTA-[Cys(4,10),D-Phe(7)]alpha-MSH(4-13) (CMSH). DOTA was also conjugated to the amino terminus of one of the highest-affinity alpha-MSH receptor-binding peptides, [Nle(4),D-Phe(7)]alpha-MSH (NDP), as a linear peptide standard. The DOTA-conjugated alpha-MSH analogs were radiolabeled with (111)In and examined for their in vitro receptor-binding affinity with B16/F1 murine melanoma cells, and their in vivo biodistribution properties were evaluated and compared in melanoma tumor-bearing C57 mice.

RESULTS

The tumor uptake values of (111)In-DOTA-ReCCMSH were significantly higher than those of the other closely related (111)In-DOTA-alpha-MSH conjugates. Even at 24 h after injection, a comparison of the tumor uptake values for (111)In-DOTA-coupled ReCCMSH (4.86 +/- 1.52 percentage injected dose [%ID]/g), CCMSH (1.91 +/- 0.56 %ID/g), CMSH (3.09 +/- 0.32 %ID/g), and NDP (2.47 +/- 0.79 %ID/g) highlighted the high tumor retention property of ReCCMSH. Rhenium-coordinated cyclization resulted in less renal radioactivity accumulation of (111)In-DOTA-ReCCMSH (8.98 +/- 0.82 %ID/g) than of (111)In-DOTA-CCMSH (63.2 +/- 15.6 %ID/g), (111)In-DOTA-CMSH (38.4 +/- 3.6 %ID/g), and (111)In-DOTA-NDP (12.0 +/- 1.96 %ID/g) at 2 h after injection and significantly increased its clearance into the urine (92 %ID at 2 h after injection). A high radioactivity uptake ratio of tumor to normal tissue was obtained for (111)In-DOTA-ReCCMSH (e.g., 489, 159, 100, and 49 for blood, muscle, lung, and liver, respectively, at 4 h after injection).

CONCLUSION

The novel ReO-coordinated cyclic structure of DOTA-ReCCMSH contributes significantly to its enhanced tumor-targeting and renal clearance properties and makes DOTAReCCMSH an excellent candidate for melanoma radiodetection and radiotherapy.

In vivo evaluation of an 111In-labeled ST-peptide analog for specific-targeting of human colon cancers

In vitro competitive binding studies of In-DOTA-NCS-6-Ahx-Phe(19)-ST[1-19] vs. 125I-Tyr(5)-6-Ahx-Phe(19)-ST[1-19] with guanylate cyclase -C (GC-C) receptors on human colon cancer LS-180 cells revealed an IC(50) value of 7.7 +/- 0.1.6 nM. The in vitro cellular residualization studies of the 111In-DOTA-NCS-ST peptide and GC-C receptor mediated stimulated cGMP production with LS-180 cells demonstrates that this peptide selectively binds to LS-180 cells in an agonistic fashion. In vivo biodistribution studies in LS-180 tumor bearing SCID mice demonstrates that the 111In-DOTA-NCS-ST peptide targets the tumor with a specific uptake of 0.94 +/- 0.31%ID/g at 1 hr p.i. and approximately 23% was retained by the tumor at 4 hrs p.i. The radioactivity cleared rapidly from the blood stream with 84.5 +/- 3.4%ID at 1h p.i. found in the urine. High activity in urine and kidney, and minimal activity in liver and intestines, demonstrates preferential clearance of the radioactivity through the renal/urinary pathway. The specific in vitro and in vivo accumulation of the radioactivity by LS-180 human colonic cancer cells highlights the potential of radiometallated-DOTA-ST analogs as diagnostic/therapeutic radiopharmaceuticals.

Radiometallated receptor-avid peptide conjugates for specific in vivo targeting of cancer cells

New receptor-avid radiotracers are being developed for site-specific in vivo targeting of a myriad of receptors expressed on cancer cells. This review exemplifies strategies being used to design radiometallated peptide conjugates that maximize uptake in tumors and optimize their in vivo pharmacokinetic properties. Efforts to produce synthetic peptide analogues that target the following three receptor systems are highlighted: Gastrin releasing peptide (GRP), alpha-melanocyte stimulating hormone (alpha-MSH), and guanylate cyclase-C (GC-C) receptors.

Synthesis and in vitro evaluation of an 111In-labeled ST-peptide enterotoxin (ST) analogue for specific targeting of guanylin receptors on human colonic cancers

BACKGROUND

Human colonic cancer cells are known to express guanylate cyclase C (GC-C) receptors for guanylin and uroguanylin. E. coli ST is a peptide with high metabolic stability that specifically binds to GC-C receptors. An in vitro evaluation of a new synthetic indium-111 labeled ST conjugate for specific targeting of human colonic cancers that express GC-C receptors was performed.

MATERIALS AND METHODS

A DOTA conjugated ST analogue DOTA-NCS-6-Ahx-Phe19-ST[1-19] (DOTA-NCS-ST) was synthesized and labeled with indium-111. The non-radioactive indium analogue (In-DOTA-NCS-ST) was also prepared in macroscopic quantities. 111In-DOTA-NCS-ST was produced as a single species (>80% RCP) and purified by HPLC. Human colon cancer CaCO-2 and T-84 cells were used to evaluate the in vitro IC50 values for GC-C receptor binding and determine the cell uptake and retention of radioactivity.

RESULTS

The DOTA-NCS-ST and In-DOTA-NCS-ST conjugates exhibit high in vitro binding affinity for GC-C receptors with IC50 values <10 nM. The in vitro cell binding studies with the 111In-DOTA-NCS-ST conjugate demonstrated that 111In-label ST internalizes in human colon cancer cells and exhibits long-term retention.

CONCLUSION

The combination of radiolabeling efficacy and specific in vitro cell uptake and retention suggests that the DOTA-NCS-ST construct holds potential for the development of diagnostic or therapeutic radiopharmaceuticals labeled with trivalent radiometals for specific targeting of human colonic cancers.

Psychosocial predictors of satisfaction among orthognathic surgery patients

This study assessed the usefulness of selected psychosocial tests and demographic measures in identifying satisfied versus dissatisfied patients who received orthognathic surgery. Data were collected prior to placement of orthodontic appliances, 1 to 2 weeks presurgery, and at 1 week, 8 weeks, 6 months, 12 months and and 2 years postsurgery. The Revised Symptom Checklist-90 (SCL-90-R) scales, the Eysenck Personality Inventory (EPI), the Sickness Impact Profile (SIP), and the Oral Health Status Questionnaire (OHSQ) were used as independent variables. Indicators from the Post-Surgical Patient Satisfaction Questionnaire (PSPSQ), which assesses patient satisfaction regarding psychosocial issues, oral functioning, and esthetics, served as a postsurgical dependent measure of patient satisfaction. Thirty-one male and 86 female subjects participated in the multisite randomized trial comparing rigid and wire fixation. Patient age was significantly correlated with patient satisfaction from 8 weeks postsurgery through 2 years postsurgery. Older patients appear to report greater postsurgical satisfaction in comparison to younger patients. The postsurgical OHSQ (esthetics subscale) and postsurgical PSPSQ (satisfaction) were significantly related at 8 weeks, 6 months, 12 months, and 2 years postsurgery. Additionally, PSPSQ (satisfaction) and postsurgical OHSQ (general oral health scale) were correlated at 12 months. The EPI, SIP, and SCL-90-R were not significantly associated with postsurgical satisfaction when assessing the entire study sample. Postsurgical qualitative data from the PSPSQ indicated that 50% of the patients reported positive outcomes in oral functioning. Sixty-five percent reported esthetic improvements, and 37% reported neurosensory loss.

Synthesis, Characterization, and Labeling with 99mTc/188Re of Peptide Conjugates Containing a Dithia-bisphosphine Chelating Agent

Radiolabeling of small receptor-avid peptides at specific predetermined chelation sites with radioactive metals has been an effective approach for production of target-specific radiopharmaceuticals for diagnosis and therapy of diseases. Among various electron-donating groups found on chelator frameworks, phosphines are unique because they display versatile coordination chemistry with a wide range of transition metals. We have recently reported the utility of a dithia-bis(hydroxymethyl)phosphine-based (P2S2) bifunctional chelating agent (BFCA) containing air-stable primary phosphine groups to form 99mTc-labeled receptor-avid peptides by the preconjugation approach. Here we report a novel strategy for labeling small peptides with both 99mTc and 188Re using the P2S2-COOH (6,8-bis[3-(bis(hydroxymethyl)phosphanyl)propylsulfanyl]octanoic acid) BFCA by a postconjugation radiolabeling approach. The first step in this approach involves the coupling of the corresponding (PH2)2S2-COOH intermediate to the N-terminus of the peptide(s). Formylation of P-H bonds with aqueous formaldehyde in the presence of HCl in ethanol affords the corresponding (hydroxymethyl)phosphine-P2S2-peptide conjugates in the form of an oxidatively stable phosphonium salt. The P2S2-peptide conjugates are generated (where the PH2 groups are converted to P(CH2OH)2 groups) by treatment of the P2S2-peptide phosphonium salt(s) with 1 M sodium bicarbonate solution at pH 8.5. Complexation of BFCA conjugates with 99mTc is achieved by direct reduction with Sn(II) tartarate to yield the 99mTc-P2S2-peptide conjugate in near quantitative yields. Complexation of the BFCA conjugates with 188Re is achieved by transchelation with 188Re citrate in yields of >/=90%. In this study, (PH2)2S2-COOH BFCA was conjugated to model peptides. The glycineglycine ethyl ester (GlyGlyOEt)-(PH2)2S2-COOH BFCA conjugate was converted to the hydroxymethylene phosphine form and complexed with 99mTc to produce the 99mTcO2-P2S2-GlyGlyOEt conjugate 8 in RCPs of >/=95%. This singular 99mTc product is stable over 24 h in aqueous solution as confirmed by HPLC. Identical retention times of the 99mTcO2-P2S2-GlyGlyOEt complex and its cold rhenium analogue (ReO2-P2S2-GlyGlyOEt) on HPLC indicates similarity in structures at the macroscopic and the tracer levels. The utility of this postconjugation strategy was further demonstrated by synthesizing a P2S2-D-Lys6-LHRH conjugate and producing its corresponding 99mTc complex in RCPs of >/=88%. Finally, the P2S2-5-Ava-BBN[7-14]NH2 bombesin (BBN) analogue was synthesized, the PH2 groups converted to P(CH2OH)2 groups and subsequently labeled with 188Re to yield a 188Re-labeled bombesin analogue with a RCP of >/=90%. The biological integrity of this conjugate was demonstrated in both in vitro and in vivo. The results of this investigation demonstrate that the (PH2)2S2-COOH BFCA can be conveniently used as a precursor for labeling small receptor-avid peptides with diagnostic (99mTc) and therapeutic (188Re) radionuclides via the postconjugation approach in high yields.

Melanoma-targeting properties of (99m)technetium-labeled cyclic alpha-melanocyte-stimulating hormone peptide analogues

Preliminary reports have demonstrated that (99m)technetium (Tc)-labeled cyclic [Cys(3,4,10), D-Phe7]alpha-MSH(3-13) (CCMSH) exhibits high tumor uptake and retention values in a murine melanoma mouse model. In this report, the tumor targeting mechanism of 99mTc-CCMSH was studied and compared with four other radiolabeled alpha-melanocyte stimulating hormone (alpha-MSH) peptide analogues: 125I-(Tyr2)-[Nle4, D-Phe7]alpha-MSH [125I-(Tyr2)-NDP]; 99mTc-CGCG-NDP; 99mTc-Gly11-CCMSH; and 99mTc-Nle11-CCMSH. In vitro receptor binding, internalization, and cellular retention of radiolabeled alpha-MSH analogues in B16/F1 murine cell line demonstrated that >70% of the receptor-bound radiolabeled analogues were internalized together with the receptor. Ninety % of the internalized 125I-(Tyr2)-NDP, whereas only 36% of internalized 99mTc-CCMSH, was released from the cells into the medium during a 4-h incubation at 37 degrees C. Two mouse models, C57 mice and severe combined immunodeficient (Scid) mice, inoculated s.c. with B16/F1 murine and TXM-13 human melanoma cells were used for the in vivo studies. Tumor uptake values of 11.32 and 2.39 [% injected dose (ID)/g] for 99mTc-CCMSH at 4 h after injection, resulted in an uptake ratio of tumor:blood of 39.0 and 11.5 in murine melanoma-C57 and human melanoma-Scid mouse models, respectively. Two strategies for decreasing the nonspecific kidney uptake of 99mTc-CCMSH, substitution of Lys11 in CCMSH with Gly11 or Nle11, and lysine coinjection, were evaluated. The biodistribution data for the modified peptides showed that Lys11 replacement dramatically decreased the kidney uptake, whereas the tumor uptakes of 99mTc-Nle11- and 99mTc-Gly11-CCMSH were significantly lower than that of 99mTc-CCMSH. Lysine coinjection significantly decreased the kidney uptake (e.g., from 14.6% ID/g to 4.5% ID/g at 4 h after injection in murine melanoma-C57 mice) without significantly changing the value of tumor uptake of 99mTc-CCMSH. In conclusion, the compact cyclic structure of 99mTc-CCMSH, its resistance to degradation, and its enhanced intracellular retention are the major contributing factors to the superior in vivo tumor targeting properties of 99mTc-CCMSH. Lys11 residue in 99mTc-CCMSH is critical to the tumor targeting in vivo, and lysine coinjection rather than lysine replacement can significantly decrease the nonspecific renal radioactivity accumulation without impeding the high melanoma-targeting properties of 99Tc-CCMSH. The metal-cyclized CCMSH molecule displays excellent potential for the development of melanoma-specific diagnostic and therapeutic agents.

Psychosocial predictors of high-risk patients undergoing orthognathic surgery

The purpose of this analysis was to identify a set of predictor variables that are prospectively related to postsurgical outcomes. Specifically, psychosocial characteristics were sought to predict postsurgical outcomes. The 5 Revised Symptom Checklist-90 (SCL-90-R) scales, the neuroticism score of the Eysenck Personality Inventory (EPI), the psychosocial domain score from the Sickness Impact Profile (SIP), and 4 scales from the Oral Health Status Questionnaire (OHSQ) were used as the predictors. A total of 31 male and 86 female subjects participated in this multicenter randomized trial, which compared rigid and wire fixation. Data were collected prior to placement of orthodontic appliances, 1 to 2 weeks presurgery, and at 1 week, 8 weeks, 6 months, and 2 years after surgery. Baseline oral health was used as an indicator of postsurgical oral health functioning. A path analytic model of influences on presurgical oral health was estimated (R2 = 0.43). The results suggest that presurgical screening of demographic characteristics (age, sex, and ethnicity), oral health (the OHSQ), quality of life issues (SIP), and personality features (SCL-90-R), accounts for 23% to 39% of the variance in postsurgical oral health outcomes. The path analysis conducted suggests that a patient's age, ethnicity, gender, and elevated scores on the EPI have indirect effects on postsurgical health. As determined by a 2-stage least squares regression model, 3 variables--the patient's presurgical oral health (per the OHSQ), pre- and postsurgical Global Severity Index (GSI) score from the SCL-90-R, and the psychosocial scale score from the SIP--were found to have a statistically significant impact on postsurgical outcomes. Additionally, the GSI, SIP, and OHSQ are reliable measures in predicting oral health outcomes.

Early sexual experiences among pregnant and parenting adolescents

One hundred sixty-six pregnant or parenting adolescent females completed a survey regarding early sexual experiences (wanted and unwanted), family dysfunction and violence, and health-risky behaviors occurring prior to age 18. Fifty-three percent had at least one unwanted sexual experience. Younger age at first unwanted sexual experience was associated with younger age at first wanted sexual experience. Adolescent females with an unwanted sexual experience, as compared to those without, were more likely to be victims of physical violence, to have run away, to be substance abusers, and to have family members with drug or alcohol problems. Four factors explained 39% of the variance in age at first pregnancy: presence of a family member with a drinking problem, age first got hit with a belt or other object by a family member, age first got drunk, and age at first wanted sexual experience. It was concluded that the prevention of teenage pregnancy entails a multifaceted approach that addresses family life, early sexual experiences, and health-risky behaviors.

99mTc-labeling and in vivo studies of a bombesin analogue with a novel water-soluble dithiadiphosphine-based bifunctional chelating agent

Recent progress in the synthesis of water-soluble phosphine ligand systems and their corresponding 99mTc complexes prompted the development of a new bifunctional chelating agent (BFCA) based on a tetradentate dithiadiphosphine framework (P2S2-COOH). The detailed synthesis of this new BFCA is described here. The corresponding 99mTc complex, 99mTc-P2S2-COOH, can be formed in >95% yield. To demonstrate the potential of this chelate to efficiently label peptides, 99mTc-P2S2-COOH was coupled to the N-terminal region of the truncated nine-amino acid bombesin analogue, 5-Ava-Gln-Trp-Ala-Val-Gly-His-Leu-Met-NH2 [BBN(7-14)], to form 99mTc-P2S2-BBN(7-14). Conjugation to the peptide was performed in borate buffer (pH 8.5) by applying the prelabeling approach in yields of >60%. In competitive binding assays, using Swiss 3T3 mouse fibroblast cells against [125I-Tyr4]bombesin, Re-P2S2-BBN(7-14) exhibited an IC50 value of 0.8 +/- 0.4 nM. The pharmacokinetic studies of 99mTc-P2S2-BBN(7-14) and its ability to target tissue expressing gastrin-releasing peptide (GRP) receptors were performed in normal mice. The 99mTc-P2S2-BBN(7-14) exhibited fast and efficient clearance from the blood pool (0.6 +/- 0.1% ID, 4 h postinjection) and excretion through the renal and hepatobiliary pathways (56.4 +/- 8.2 and 28.1 +/- 7.9% ID, 4 h postinjection, respectively). Significant uptake in the pancreas was observed (pancreatic acini cells express bombesin/GRP receptors), producing pancreas:blood and pancreas:muscle ratios of ca. 22 and 80, respectively, at 4 h postinjection.

Design and characterization of alpha-melanotropin peptide analogs cyclized through rhenium and technetium metal coordination

alpha-Melanocyte stimulating hormone (alpha-MSH) analogs, cyclized through site-specific rhenium (Re) and technetium (Tc) metal coordination, were structurally characterized and analyzed for their abilities to bind alpha-MSH receptors present on melanoma cells and in tumor-bearing mice. Results from receptor-binding assays conducted with B16 F1 murine melanoma cells indicated that receptor-binding affinity was reduced to approximately 1% of its original levels after Re incorporation into the cyclic Cys4,10, D-Phe7-alpha-MSH4-13 analog. Structural analysis of the Re-peptide complex showed that the disulfide bond of the original peptide was replaced by thiolate-metal-thiolate cyclization. A comparison of the metal-bound and metal-free structures indicated that metal complexation dramatically altered the structure of the receptor-binding core sequence. Redesign of the metal binding site resulted in a second-generation Re-peptide complex (ReCCMSH) that displayed a receptor-binding affinity of 2.9 nM, 25-fold higher than the initial Re-alpha-MSH analog. Characterization of the second-generation Re-peptide complex indicated that the peptide was still cyclized through Re coordination, but the structure of the receptor-binding sequence was no longer constrained. The corresponding 99mTc- and 188ReCCMSH complexes were synthesized and shown to be stable in phosphate-buffered saline and to challenges from diethylenetriaminepentaacetic acid (DTPA) and free cysteine. In vivo, the 99mTcCCMSH complex exhibited significant tumor uptake and retention and was effective in imaging melanoma in a murine-tumor model system. Cyclization of alpha-MSH analogs via 99mTc and 188Re yields chemically stable and biologically active molecules with potential melanoma-imaging and therapeutic properties.

Child sexual revictimization by multiple perpetrators

OBJECTIVE

The objectives of this study were to describe feelings, disclosure characteristics, family dysfunction, and health risky behaviors in those adolescents having unwanted sexual experiences (USE; any kind of sexual touching that was bad, uncomfortable, or forced) with multiple perpetrators and to compare these parameters with those adolescents having USE(s) with single perpetrators.

METHOD

A cross-sectional survey of consecutive waiting room patients from four clinic sites was done in 538 adolescents and young adults; 76% of the study population were Hispanic and over half were poor. One hundred sixty-one subjects with single perpetrator USE(s) were compared with 97 subjects who had USE(s) with more than one perpetrator.

RESULTS

Victims of multiple perpetrators were more likely than victims of single perpetrators to react with self-blame and delay disclosure of USE due to shame. When compared with victims of single perpetrators, those with multiple perpetrators were more likely to disclose their USE to protect self or others or because they became weary or intolerant of the abuse. Although family violence and substance abuse were common in both victims of single and multiple perpetrators of USE, these factors appeared to potentiate the likelihood of repeated victimization in childhood. Prevalence of health risky behaviors did not differ between the two groups.

CONCLUSIONS

The findings indicated that sexual revictimization by multiple perpetrators is not uncommon and suggest that abused children should be questioned about this possibility. Children and teenagers who have USE(s) with more than one perpetrator may have more difficulties with psychological recovery due to increased shame and self-blame.

Unwanted and illegal sexual experiences in childhood and adolescence

Three hundred forty-two anonymous surveys regarding unwanted sexual experiences (USE) were filled out in three clinic sites: a pediatric sexual abuse clinic, family practice clinic, and family planning clinic. In the latter two clinics, 40% of females and 16% of males had at least one unwanted sexual experience prior to turning 18 years old. Only 91% of the sexual abuse clinic patients indicated their experience was unwanted. In addition, 27% of the subjects had wanted sexual experiences that were illegal and underreported: These experiences involved a partner at least 4 years older or younger. While feelings of victimization were most common, self-blame and naivete about the abuse were also frequently reported, especially in those who had an USE with a peer. Ambivalence, self-blame, and peer pressure were associated with a lower tendency to disclose one's USE. Although unwanted and illegal sexual experiences were less common in Hispanic females, feelings of self-blame and ambivalence regarding their USE were more frequent in comparison with White females. These findings have important investigative and therapeutic implications for professionals who encounter victims of sexual abuse.

Child sexual abuse: An undermining of the polis

This paper explores the sexual abuse literature and the political participation literature for possible linkages. Research on political participation indicates low levels of political trust and damaged self-esteem have important impacts on style and level of political involvement. The literature on child sexual abuse indicates potential root causes for lowered trust and self-esteem which have implications for adult participation in the civic arena. Sexual abuse has negative effects on individual victims and also undermines the foundations of democratic societies.

Decrease in locus coeruleus [3H]idazoxan binding site density in genetically epilepsy-prone (GEPR) rats

Deficits in norepinephrine synthesis, transmitter level, turnover and reuptake have been reported in the brain of genetically epilepsy-prone (GEPR) rats. We investigated the hypothesis that these alterations may trigger a compensatory downregulation of locus coeruleus alpha 2-adrenergic receptors and an upregulation of postsynaptic alpha 2-adrenergic receptor density in forebrain regions of GEPR rat brain. alpha 2-adrenergic receptor density was measured in the locus coeruleus and 7 forebrain regions of control and GEPR rats by in vitro [3H]idazoxan autoradiography. Specific [3H]idazoxan binding site density was decreased significantly in the locus coeruleus of both GEPR-3 and GEPR-9 rats compared to controls. No significant differences in specific [3H]idazoxan binding were observed in the 7 forebrain regions of GEPR-9 rats compared to control. Reduced locus coeruleus alpha 2-adrenergic receptor density in GEPR rats may produce a net increase in locus coeruleus noradrenergic cell firing, an effect which could, in part, offset the impact of reduced noradrenergic influence in GEPR rat forebrain. Additionally, decreased norepinephrine levels in GEPR rat brain may be a long-term consequence of reduced alpha 2-adrenergic receptor-mediated inhibition of locus coeruleus firing activity.

The effect of ligand structure on glutathione-mediated decomposition of propylene amine oxime derivatives

Tetramethylpropyleneamine oxime (TMPAO) was synthesized and complexed to 99mTc. 99mTc-TMPAO samples, when challenged with reduced glutathione (GSH), were shown to have two GSH sensitive components, similar to a mixture of d,l and meso 99mTc-HMPAO. One component had a GSH-induced second-order dissociation rate constant (K2) similar to 99mTc-meso-HMPAO. Despite the presence of a large fraction of this component in these samples, brain uptake and autoradiographic studies with 99mTc-TMPAO were equivalent to 99mTc-d,l-HMPAO suggesting that both the d,l and meso 99mTc-TMPAO isomers are efficiently trapped in brain.

Formation of a stable 99mTc-tri-hydrazidophosphine oxide (99mTc-THP) chelate

Atri-hydrazidophosphine oxide (THP) ligand was synthesized and used to complex 99mTc in high yield (> 95%) by Sn(II) reduction of 99mTcO4-. 99mTc-THP has excellent stability in both 0.9% acqueous NaCl at neutral pH and in human serum at 37 degrees C. Biodistribution studies indicate minimal organ specificity and no significant in vivo release of 99mTcO4-. The ease of 99mTc complexation with THP and the high stability of 99mTc-THP suggests that this ligand may be used as a basis for the development of new imaging agents.

Radiographic and neuro-SPECT imaging in an immature third ventricle teratoma: case report

We report a case of an immature teratoma of the third ventricle, which was preoperatively thought to be a choroid plexus papilloma. The diagnosis was made by biopsy since the radiographic (CT, MRI), angiographic and scintigraphic findings ([99mTc]pertechnetate, 99mTc-DTPA, 99mTc-HMPAO brain SPECT) were nonspecific. Disruption of the blood-brain barrier is the mechanism for radionuclidic and contrast tumoral uptake and is demonstrated by marked contrast enhancement on CT and focal concentration on [99mTc]pertechnetate and 99mTc-DTPA images. No suppression of [99mTc]pertechnetate tumor uptake was observed following the administration of potassium perchlorate. Increased concentration of tumor protein is suggested by the increased signal on the T1-weighted magnetic resonance images and high [99mTc]pertechnetate uptake. The tumor's detection on the 99mTc-HMPAO brain SPECT was due to its intraventricular location. A number of potential mechanisms for brain tumor localization of 99mTc-HMPAO are discussed.

Evaluation of alkylated derivatives of 99mTc-propylene amine oxime (99mTc-PnAO)

Several lipophilic di-alkylated derivatives of propylene amine oxime (PnAO were complexed to 99mTc. Assessment of the 99mTc-PnAO derivatives included biodistribution and qualitative autoradiography. All of the derivatives studied penetrated the intact blood-brain-barrier, with the 99mTc-dibutyl-PnAO complex exhibiting the lowest initial brain uptake while the 99mTc-diethyl-PnAO and the 99mTc-dipropyl-PnAO complexes possessing nearly identical initial brain uptake as compared to 99mTcPnAO. Qualitative autoradiographs revealed significant loss of image resolution with extended time post injection indicative of rapid radiopharmaceutical washout. Although increasing alkyl chain length did not enhance initial brain uptake, the data demonstrates that limited modification of the PnAO ligand structure can be performed without decreasing cerebral uptake of the respective 99mTc complex.

Retention of [99mTc]-d,l-HM-PAO in rat brain: an autoradiographic study

The regional cerebral distribution pattern of [99mTc]-d,l-HM-PAO in rat brain was studied by autoradiography. The regional cerebral uptake of this tracer is related to regional cerebral blood flow (rCBF); however, the ratio of retained radioactivity (determined by digital imaging techniques) in gray matter compared to white matter is lower than that reported for the blood flow ratio. Considerable inhomogeneity is observed in cortical gray matter for at least 60 min postinjection, demonstrating that minimal, if any, cerebral redistribution of this agent occurs.

Two populations of tyrosine hydroxylase-positive cells occur in the spinal cord of the chick embryo and hatchling

The existence of tyrosine hydroxylase (TH)-containing neurons in the spinal cord of the chick embryo was investigated by anti-TH immunocytochemistry. Two populations of intensely immunostained cells were observed along the entire extent of the cord, beginning late in chick embryogenesis. One group of TH-positive cells was particularly numerous and found ventral to the central canal. The other group, which was smaller in number, was located along the superficial and lateral border of the dorsal horn of the spinal cord. When examined by the glyoxylic acid histofluorescence technique, cells could be visualized only very infrequently ventral to the central canal, and not at all within the dorsal horn. However, after pretreatment of hatchlings with the catecholamine synthesis precursor L-DOPA, cells ventral to the canal were readily observed by histofluorescence, while the dorsally located cells seldom visualized. Since these populations of TH-positive cells appear to only partially express the catecholaminergic phenotype, these cells may provide a model in which factors regulating the expression of neurotransmitter phenotypes can be examined in neurons of the developing CNS.

Analysis of the change in number of serotonergic neurons in the chick spinal cord during embryonic development

The existence of serotonin (5-HT)-containing neurons in the spinal cord of the chick embryo was examined by anti-5-HT immunocytochemistry. The first immunoreactive cells were observed in embryos at 7 days of incubation (E7) and were initially located within the floor plate of the early spinal cord. By E9, immunostained cells occurred throughout the length of the spinal cord and were frequently encountered in most transverse sections of the cord. When examined at later embryonic ages of E12, 17 and at hatching (E21 or 22), the 5-HT cells became progressively more difficult to find with the advancing age of the embryos. To determine if this population of spinal cord 5-HT neurons actually diminished during development, a detailed quantitative analysis was undertaken to estimate the number of 5-HT cells in the cord of chick embryos at different ages. The results of this investigation demonstrated that the size of the 5-HT neuronal population rose rapidly from E7 and plateaued (at approximately 3500 neurons) between E9 and E12. As anticipated, the number of 5-HT cells at E17 decreased at all cord levels. Surprisingly, however, the number of spinal cord 5-HT neurons at hatching increased (depending on the cord level) either back to, or above, the counts estimated for the earlier ages of E9 and E12. Therefore, cells expressing the 5-HT phenotype in the spinal cord of the chick embryo persist throughout the period of embryonic development, rather than appear transiently.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral uptake and retention of 99Tcm-hexamethylpropyleneamine oxime (99Tcm-HM-PAO)

A new radiopharmaceutical, 99Tcm-hexamethylpropyleneamine oxime (99Tcm-HM-PAO) is described. This agent displays considerable promise for imaging cerebral blood flow. In studies in rats and one human volunteer, 99Tcm-HM-PAO demonstrates good brain uptake, prolonged retention of activity in the brain, and slow regional redistribution. These properties suggest that this new radiopharmaceutical is ideal for single photon emission tomographic (SPECT) imaging of cerebral blood flow.

99mTc-propylene amine oxime (99mTc-PnAO); a potential brain radiopharmaceutical

Propylene amine oxime (PnAO) forms a neutral lipid soluble complex with 99mTc. 99mTc-PnAO can be prepared by simple reduction of 99mTc-pertechnetate with stannous ion in the presence of excess PnAO in saline at or near neutral pH. This agent will passively penetrate biological membranes including the intact blood-brain barrier (BBB) as evidenced by the high brain uptake observed shortly after IV injection. The first-pass extraction efficiency in baboons was estimated to be 80% at normal blood flow. This agent or a derivatized form of 99mTc-PnAO may be useful in assessment of regional cerebral blood flow (rCBF) in humans.

A neutral lipophilic complex of 99mTc with a multidentate amine oxime

Propylene amine oxime, 3,3'-(1,3-propanediyldiimino)bis(3-methyl-2-butanone)dioxime, (PnAO) forms a neutral lipophilic complex with 99mTc in greater than 95% yield at room temperature at pH 5-10. The complex can be prepared with generator produced 99mTc using 10(-5) M SnC4H4O6 as the reducing agent at ligand concentrations as low as 3 X 10(-5) M. It is stable in saline solutions for as long as 24 h. [99mTc]PnAO may be useful as an imaging agent which passively diffuses across the blood brain barrier.

Biodistribution of lipophilic 99mTc complexes of cyclam derivatives

Several n-alkyl-cyclam derivatives were synthesized which form stable single component cationic chelates with 99mTc. These results suggest that the cyclam moiety in these derivatives complexes 99mTc in the same manner as the underivatized macrocycle. Biodistribution studies in mice show that all of these chelates are cleared from circulation by both the kidneys and liver. The ratio and rates of clearance by these organ systems is related to lipid solubility. None of the lypophilic-cationic-99mTc agents show any significant myocardial uptake. Also, these chelates show no significant ability to penetrate the blood-brain-barrier.

The behavior of neutral amine oxime chelates labelled with Tc at tracer level

Neutral 99mTc-chelates were formed with propylene amine oxime, 3,3'-(1,3-propanediyldiimino)bis-(3-methyl-2-butanone)-dioxime and other PnAO analogues. Even though the other amine oxime ligands form neutral chelates with 99mTc, the stability, lipophilic and the brain uptake characteristics are less desirable than [99mTc]-PnAO. These results demonstrate that slight modifications in the amine oxime ligand backbone produces significant effects on the chemical and biological behavior of the [99mTc]dioxime chelates.