Gamma-ray imaging with a Si/CsI(Tl) Compton detector.

We present results from Compton imaging of gamma-ray sources using an instrument constructed from thin silicon scattering detectors and CsI(Tl) absorbing detectors. We have successfully imaged single and double point sources for several common radioactive isotopes ((137)Cs, (60)Co, (22)Na, (54)Mn). The measured angular resolution is 11.6( composite function) FWHM at 662keV. In parallel with the hardware effort, a GEANT4-based simulation code was developed. Comparisons between real and simulated data are discussed.

Results of gastric interposition for reconstruction of the pharyngoesophagus.

BACKGROUND: Free jejunal transfer has become the standard technique for reconstruction of the proximal pharynx and hypopharynx. Gastric tube interposition is an effective alternative when resection extends below the thoracic inlet. This study was done to determine current indications, review morbidity and mortality rates, and to define clinical and pathologic determinants of survival associated with this procedure. METHODS: We reviewed the records of 32 patients who underwent gastric tube interposition for reconstruction of the pharyngoesophagus from 1987 to 1997. RESULTS: The overall complication rate was 50%. Complications were more frequent in the reoperative group (22% vs 66%, P < .05). The overall fistula rate was 31%. The overall mortality rate was 12%. Ultimately, 71% of patients resumed oral feedings. The 5-year actuarial survival rate was 22%. Unfavorable prognostic factors associated with significantly reduced survival (P < . 05) included margin positive resection, positive lymph node involvement, and operations done for recurrent tumor CONCLUSIONS: Reconstruction of the pharyngoesophagus with gastric tube interposition is indicated for primary tumors of the hypopharynx and cervical esophagus with inferior extension below the thoracic inlet and recurrent tumors or benign strictures in which free jejunal transfer is not feasible or has failed. It can be done with acceptable morbidity and mortality and provides reasonable expectations for long-term survival and resumption of oral intake.

Ovarian responses in women to recombinant follicle-stimulating hormone and luteinizing hormone (LH): a role for LH in the final stages of follicular maturation.

During the follicular phase of the menstrual cycle, FSH stimulates follicular growth, granulosa cell aromatase activity, induction of LH receptors on the granulosa cell membrane, and estradiol secretion. As a result of negative feedback of estradiol on the pituitary, serum FSH concentrations decline. Despite the fall in FSH concentrations, the maturing follicle continues to develop to the preovulatory stage. In a prospective randomized trial, we tested the hypothesis that a key mechanism by which the dominant follicle continues to develop in the face of decreasing concentration of FSH is by acquiring LH responsiveness. In 24 women, pituitary gonadotropin secretion was down-regulated with a GnRH agonist. Follicular growth was then stimulated with recombinant human FSH (r-hFSH) until a 14-mm follicle was identified by ultrasound. The women were then randomized to 1 of 4 groups for a 2-day period: continued r-hFSH treatment, substitution of r-hFSH with saline, low dose r-hLH (150 IU, twice daily), or high dose r-hLH (375 IU, twice daily). Serum estradiol concentrations in the women receiving saline declined by the end of the 2-day randomization period. In contrast, serum estradiol concentrations continued to rise in women receiving either r-hFSH or r-hLH compared with those in the saline-treated group (P < 0.05). Pregnancies occurred in each of the gonadotropin treatment groups. These findings indicate that once FSH initiates follicular growth, either FSH or LH is capable of sustaining follicular estradiol production. Extrapolating these findings to the normal menstrual cycle suggests that the maturing follicle may continue to develop in the presence of diminishing FSH concentrations by acquiring the capacity to respond to LH.

Efficacy of treatment for unexplained infertility.

OBJECTIVE: To analyze the efficacy and cost-effectiveness of alternative treatments for unexplained infertility. DESIGN: Retrospective analysis of 45 published reports. SETTING: Clinical practices. PATIENT(S): Couples who met criteria for unexplained infertility. Women with Stage I or Stage II endometriosis were included. INTERVENTION(S): Observation; clomiphene citrate (CC); gonadotropins (hMG); IUI; and GIFT and IVF. MAIN OUTCOME MEASURE(S): Clinical pregnancy rate. RESULT(S): Combined pregnancy rates per initiated cycle, adjusted for study quality, were as follows: no treatment = 1.3%-4.1%; IUI = 3.8%; CC = 5.6%; CC + IUI = 8.3%; hMG = 7.7%; hMG + IUI = 17.1%; IVF = 20.7%; GIFT = 27.0%. The estimated cost per pregnancy was $10,000 for CC + IUI, $17,000 for hMG + IUI, and $50,000 for IVF. CONCLUSION(S): Clomiphene citrate + IUI is a cost-effective treatment for unexplained infertility. If this treatment fails, hMG + IUI and assisted reproduction are efficacious therapeutic options.

Glucocorticoid repression of gonadotropin-releasing hormone gene expression and secretion in morphologically distinct subpopulations of GT1-7 cells.

Two morphologically distinct subpopulations of GT1-7 cells have been characterized and examined for their responsiveness to glucocorticoids. Type I cells have a neuronal phenotype, extending many lengthy processes, and express neuronal, but not glial, markers. Type II cells show weaker or negative immunostaining for neuronal markers and exhibit fewer processes. The effect of glucocorticoids on gonadotropin-releasing hormone (GnRH) secretion and gene expression was compared in type I and type II GT1-7 cells. For secretion studies, cells were attached to Cytodex beads and perifused with control medium or medium containing dexamethasone (dex). The high level of GnRH secreted by type I cells was slightly enhanced in the presence of dex, whereas dex rapidly and profoundly decreased the already low level of GnRH secreted by type II cells. Immunocytochemistry for GnRH showed dark reaction product in the cell bodies and processes of type I cells and little or no immunoreactivity in type II cells. Both the endogenous mouse GnRH mRNA and the transcriptional activity of a mouse GnRH promoter luciferase reporter gene plasmid were suppressed to a greater extent in type II cells than in type I. In electrophoretic mobility shift assays, there was no difference between type I and type II nuclear extracts in the pattern of protein-DNA complexes formed on two previously identified negative glucocorticoid response elements located at -237 to -201 and -184 to -150 bp of the mouse promoter. Both cell types contained glucocorticoid receptors (GR) by Western blot analysis. Cytosols from type I or type II cells were incubated with [3H]dex to obtain GR binding parameters. Binding data were consistent with a one-site model for dex binding in each case. Small differences in Kd (1.7 nM, type I; 3.1 nM, type II) or Bmax (approximately 3600 sites/cell, type I; approximately 1800 sites/cell, type II) were not likely to account for the differential sensitivity to dex treatment. In conclusion, nuclear alterations in type II cells leading to greater transcriptional susceptibility to dex, coupled with low GnRH storage levels, may be reflected in exquisite sensitivity of GnRH secretion to glucocorticoid repression. This represents the first example of a steroid hormone acting directly on GnRH-producing cells to alter GnRH secretion.

Incidence of bacteremia associated with chorionic villus sampling.

OBJECTIVE: To assess the frequency of transient bacteremia among women undergoing transabdominal and transcervical chorionic villus sampling (CVS). METHODS: One hundred fourteen women undergoing CVS consented to participate in a university review board-approved study protocol. Exclusion criteria included known cardiac valve anomaly or replacement (or other prosthetic) and antibiotic use within the preceding 21 days. Blood cultures (aerobic and anaerobic) were drawn by a single operator on all patients, before CVS and within 15 minutes after completing CVS. Either the catheter tip or needle tip aspirate from each procedure was also sent for culture. RESULTS: Post-procedure bacteremia was detected in two (1.8%) of the patients undergoing CVS. These two patients both had their procedures performed transcervically, resulting in a 4.1% (two of 49) bacteremia rate after transcervical CVS, compared to none (zero of 65) in the transabdominal group (P = .36). The incidence of positive cultures from sampling instruments was also higher in the transcervical group (16.3 versus 0%; P = .003), but did not result in comparable rates of bacteremia among patients with positive instrument cultures. CONCLUSIONS: In this study, CVS was associated with a low rate of bacteremia, regardless of the procedure route. Recommendations for antibiotic prophylaxis in women with abnormal cardiac valves should parallel those for spontaneous vaginal delivery and other comparable genitourinary procedures.

Differences in shame and pride as a function of children's gender and task difficulty.

3-year-old children were presented with easy and difficult tasks and their emotional responses of shame and pride were observed. No shame was shown when subjects succeeded on the tasks and no pride was shown when they failed. Significantly more shame was shown when subjects failed easy tasks than when they failed difficult tasks, and significantly more pride was shown when subjects succeeded on difficult than on easy tasks. While there were no sex differences in task failures, girls showed more shame than boys. There were no sex differences in pride when subjects succeeded.

Self development and self-conscious emotions.

In each of 2 studies, the mirror-rouge technique was used to differentiate children into those who showed self-recognition and those who did not. In Study 1, 27 children (aged 9-24 months) were observed in 2 experimental situations thought to differentially elicit fear and embarrassment behaviors. In Study 2, 44 children (aged 22 months) were seen in the situations of Study 1 and 3 additional contexts thought to elicit embarrassment behavior. The results of both studies indicate that embarrassment but not wariness was related to self-recognition.

Role of Fluosol-DA 20% in prehospital resuscitation.

Fluosol-DA 20% (FDA-20) resuscitation has been proposed for prehospital therapy of hemorrhagic shock (HS). Acute HS (mean arterial pressure 60 mm Hg X 90 min, then 40 mm Hg X 30 min) in 24 splenectomized dogs was treated with 50 ml/kg of lactated Ringer's solution (RL) plus a volume equal to 105% of shed blood volume of FDA-20 (group 1), FDA-20 carrier Annex solution (group 2), or RL (group 3). Cardiopulmonary, hemopoietic, hemodynamic, and organ function parameters were measured preshock, at the end of shock, and at 30 and 60 min, and 24 h after resuscitation. FDA-20 produced effective volume expansion, oxygen delivery, and oxygen consumption. The FDA-20 appeared to affect organ function and cells adversely as reflected by a fall in red cell mass and platelet levels and by a rise in liver enzymes, BUN, and serum creatinine. Both the FDA-20 and Annex solution led to a reduction in serum proteins including serum albumin, serum globulin, immunoglobulin-G, and fibrinogen. These reductions are probably due to an oncotically driven factor which appears to maintain an optimal lymph to plasma oncotic ratio. The hydroxyethyl starch in the FDA-20 and the Annex solution, thus, would drive the plasma proteins into the interstitial space. The prolonged prothrombin times and the activated partial thromboplastin times after FDA-20 may be due, in part, to a reduction in the coagulation proteins, although these were not measured. Pending further studies designed to assess the effects of FDA-20 on possible cellular and multiple organ toxicity, clinical studies are premature and unwarranted.

Reactivation: priming forgotten memories in human infants.

3-month-old infants, trained to produce movement in an overhead crib mobile by footkicking, showed no evidence of remembering the learned association during a cued recall test 14 days later. Infants who received a reactivation treatment 24 hours prior to the 2-week retention test, however, performed at a level not different from that observed immediately following training. A reactivation treatment administered to a group of infants without prior training did not enhance responding during the retention session 24 hours later. Different measures of retention that have previously been used with 3-month-olds were differentially sensitive to the reminder procedure. The finding that forgotten memories can be remembered through a "prior cuing" procedure illustrates that much of the forgetting of young infants may be attributable to failures in retrieval, rather than to failure in encoding or storage (i.e., memory deficits) as has previously been assumed.

Organization of infant memory.

The differential retrieval of specific details and general features was studied in a conditioning paradigm with 3-mo.-olds. Infants learned to move a crib mobile by foot kicking and produced high response rates during cued-recall tests with the same components after retention intervals of 24, 48, 72, and 96 hr. Use of a novel mobile during retention tests significantly reduced responding for as long as 3 days after training. As time since training increased, however, response rate gradually increased until, after 96 hr., it was high and indistinguishable from response to the original mobile. The latter was interpreted as (a) the failure to detect specific details as novel after 96 hr. and (b) the use of general features of the novel mobile as an instance of the general class "mobiles" as retrieval cues. The data demonstrate that access to general visual features persists longer than access to specific visual details.

Immediate and long-term memory for reinforcement context: the development of learned expectancies in early infancy.

Infants were pretrained to move crib mobiles containing 6 or 10 identical objects by means of footkicking and were then exposed to a reinforcer containing only 2 objects. Relative to infants with no prior history of reinformcement with either of the "larger mobiles, infants shifted to the "smaller" mobile had higher kick rates, and, in addition, their visual attention decreased and negative vocalizations increased. These effects were not transient but persisted 24 hours later in infants experiencing the larger (10- to 2-object) shift. The results suggested that infants develop reward-expectation habits which continue to influence behavior for periods of at least 24 hours.

Reactivation of infant memory.

Three-month-old infants learned to activate a crib mobile by means of operant footkicks. Retention of the conditioned response was assessed during a cued recall test with the nonmoving mobile. Although forgetting is typically complete after an 8-day retention interval, infants who received a reactivation treatment--a brief exposure to the reinforcer 24 hours before retention testing--showed no forgetting after retention intervals of either 2 or 4 weeks. Further, the forgetting function after a reactivation treatment did not differ from the original forgetting function. These experiments demonstrate that (i) "reactivation" or "reinstatement" is an effective mechanism by which early experiences can continue to influence behavior over lengthy intervals and (ii) memory deficits in young infants are best viewed as retrieval deficits.

A conditioning analysis of infant long-term memory.

The long-term retention of conditioned operant footkicks by 3-month-old infants was assessed in 2 studies. In both, infants were trained in a conjugate reinforcement paradigm in which footkicks produced conjugate activation of the components of an overhead crib mobile. After 2 training sessions, retention (cued recall, savings) was assessed cross-sectionally in a third session scheduled after varying intervals. In experiment 1, 32 infants were tested after intervals of 48, 72, 96, or 120 hours; in experiment 2, 24 infants were tested after 96, 144, 192, or 336 hours. No evidence of forgetting was observed for as long as 192 hours following original training. Although both retention measures indicated a significant memory deficit in the group tested after 336 hours (2 weeks), some individuals continued to exhibit substantial recall and savings after this retention interval. A conditioning analysis was viewed as a logical means by which to bridge the gap between animal and adult human models of memory.