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L L Anderson

Publications and source records attributed to L L Anderson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Development of rabbit embryos during a 96-h period of in vitro culture after superovulatory treatment under conditions of elevated ambient temperature.

The effects of elevated ambient temperature on the response to exogenous gonadotropins were evaluated in female New Zealand White rabbits exposed to 33+/-1 degrees C (mean +/- SE) and 10-30% relative humidity (8 h/day) during a 5-day period. Does were treated with pFSH (0.3 mg/0.3 ml Standard Armour) twice daily during three consecutive days with a minimum interval of 8 h between injections. Six hours after the last FSH injection all does were removed from the experimental chamber, given hCG (25 IU/kg) and paired overnight. Nineteen hours after pairing, embryos were flushed from the reproductive tracts, evaluated, and subjected to in vitro culture during a 96-h period. The ovulatory responses to exogenous gonadotropins and fertilization rates did not differ significantly under conditions of elevated ambient temperature, whereas fewer blastocysts and increased number of degenerate embryos were observed after culture. We conclude that although hyperthermia was induced during exposure to elevated ambient temperature, it did not alter the ovulatory responses to gonadotropin treatment and plasma concentrations of FSH and LH compared with does in a thermoneutral environment. Exposure of donor rabbits to elevated ambient temperature before mating, however, increased embryonic degeneration.

Animals↗
PubMed1999

Evaluation and management of nonmelanoma skin cancer. The military perspective.

As the incidence of melanoma skin cancer continues to increase in this country, so does the need for early detection and treatment of these tumors. This article discusses a military skin cancer screening clinic that encourages patient participation and the criteria and statistics regarding the different treatment modalities we employ to treat these skin cancers.

Health Services Accessibility↗
PubMed1999

Functional fitting of interstitial brachytherapy dosimetry data recommended by the AAPM Radiation Therapy Committee Task Group 43. American Association of Physicists in Medicine.

This work was undertaken to expedite implementation of the AAPM Task Group 43 recommendations, which call for significant modifications in the way dose is calculated for interstitial sources of 192Ir, 125I, and 103Pd as well as significant changes in the dose rate constant for 125I sources. The TG43 recommendations include a new formalism for dose calculation at points defined by the radial distance, r, from the source center and the angle, theta, that such a radius makes with the source axis. For each source type, values are tabulated for the radial dose function, the anisotropy function, and the anisotropy factor. The TG43 report includes fitting functions for the radial dose function in the form of polynomials, which are poorly behaved outside the range of fitted data. No functions are offered for the anisotropy function data or the anisotropy factor data, both of which could profit from some smoothing by such functions. We have found a double exponential fit to the radial dose function that not only approximates the data adequately but also appropriately approaches zero for very large distances. The anisotropy function is conveniently fit with a form of type 1 - f(r,theta)cos(theta)e(cr), which is exactly 1 at theta=90 degrees and approaches 1 for large r (for c<0), where f(r,theta) is a selected polynomial in the two variables. The form chosen for the anisotropy factor was 1 - (a+br)e(cr), which appropriately approaches 1 for large r (and c<0). Functional fits of these types are expected to facilitate implementation of TG43 recommendations, in that they may be either incorporated into dose algorithms or used to generate lookup tables of either the x, y or the r, theta format.

Algorithms↗
PubMed1999

Permanent prostate seed implant brachytherapy: report of the American Association of Physicists in Medicine Task Group No. 64.

There is now considerable evidence to suggest that technical innovations, 3D image-based planning, template guidance, computerized dosimetry analysis and improved quality assurance practice have converged in synergy in modern prostate brachytherapy, which promise to lead to increased tumor control and decreased toxicity. A substantial part of the medical physicist's contribution to this multi-disciplinary modality has a direct impact on the factors that may singly or jointly determine the treatment outcome. It is therefore of paramount importance for the medical physics community to establish a uniform standard of practice for prostate brachytherapy physics, so that the therapeutic potential of the modality can be maximally and consistently realized in the wider healthcare community. A recent survey in the U.S. for prostate brachytherapy revealed alarming variance in the pattern of practice in physics and dosimetry, particularly in regard to dose calculation, seed assay and time/method of postimplant imaging. Because of the large number of start-up programs at this time, it is essential that the roles and responsibilities of the medical physicist be clearly defined, consistent with the pivotal nature of the clinical physics component in assuring the ultimate success of prostate brachytherapy. It was against this background that the Radiation Therapy Committee of the American Association of Physicists in Medicine formed Task Group No. 64, which was charged (1) to review the current techniques in prostate seed implant brachytherapy, (2) to summarize the present knowledge in treatment planning, dose specification and reporting, (3) to recommend practical guidelines for the clinical medical physicist, and (4) to identify issues for future investigation.

Brachytherapy↗
PubMed1999

Long-term growth after hypophyseal stalk transection and hypophysectomy of beef calves.

Hypothalamic hormones regulate episodic and basal secretion of hormones from the anterior pituitary gland that affect metabolism and growth in cattle. This study focused on long-term growth in young calves subjected to hypophysectomy (HYPOX), hypophyseal stalk transection (HST), and sham operation control (SOC). Cross-bred (Hereford x Aberdeen Angus) and Hereford, and Aberdeen Angus calves were HYPOX (n = 5), HST (n = 5), or SOC (n = 8) at 146 +/- 2 days of age, whereas another group was HST (n = 5) or SOC (n = 7) at 273 +/- 5 days of age. Body weight was determined every 21 days from birth to 1008 days of age. Anterior vena cava blood was withdrawn at 4-day intervals from day 64-360 for RIA of GH, TSH, T4, T3, and LH, and at 20-min intervals for 480 min to determine episodic hormone secretion. Daily feed intake was determined in HST and SOC calves during an 80-day period. Birth weight averaged 35 +/- 1 kg (+/- SE) and was 142 +/- 4 kg at 126 days and 208 +/- 8 kg at 252 days before surgery. From day 146-1008, growth was arrested (P < 0.001) in HYPOX (0.06 +/- 0.01 kg/day) compared with SOC (0.50 +/- 0.04 kg/day) calves. Growth continued but at a significantly lower rate (P < 0.05) in calves HST at 146 days (0.32 +/- 0.07 kg/day) and 273 days (0.32 +/- 0.06 kg/day) compared with SOC (0.50 +/- 0.09 kg/day). Growth continued to be impaired to 1008 days, but more so in those HST at 146 days (432 +/- 43 kg BW) than 273 days (472 +/- 5 kg BW) and less (P < 0.05) than SOC (586 +/- 37 kg BW). Daily feed intake was consistently less (P < 0.05) in HST compared with SOC calves. Although episodic GH secretion was abolished and peripheral serum GH concentration remained consistently lower in HST (2.4 ng/ml) than SOC (5.5 ng/ml; P < 0.01), the calves continued to grow throughout 1008 days. Peripheral serum TSH concentration was less (P < 0.05) HST compared with SOC calves. There was an abrupt decrease (P < 0.001) in serum T4 (4-fold) and T3 (3-fold) concentration after surgery that remained to 360 days in HST compared with SOC calves. At the time calves were killed, pituitary gland weight was markedly reduced (P < 0.001) in HST (0.18 +/- 0.01 g/100 kg BW) compared with SOC (0.54 +/- 0.03 g/100 kg BW). Histological examination of pituitary glands from HST calves indicated the persistence of secretory GH and TSH cells in the same areas of the adenohypophysis as SOC calves. Coronal sections of the gland stained with performic acid-Alcian blue-periodic acid-Schiff-orange G, revealed GH and TSH secreting cells in HST calves similar to controls. These results indicate that long-term growth continues, but at a slower rate, after hypophyseal stalk transection of immature calves in spite of complete abolition of episodic GH secretion and consistently decreased basal secretion of GH, TSH, T4, and T3 compared with sham-operated animals. Growth was abolished after hypophysectomy of immature calves in which circulating GH and TSH was undetectable.

Animals↗
PubMed1999

Pregnancy, parturition, and lactation in hypophyseal stalk-transected beef heifers.

Progesterone secretion is crucial for maintaining pregnancy to parturition in mammalian species, and in cattle the corpus luteum is the primary source of this hormone. This study determined the roles of prolactin (PRL), growth hormone (GH) and luteinizing hormone (LH) in the luteotropic process in beef heifers hypophyseal stalk-transected (HST, n=7) or sham operated (sham operated controls, SOC, n=9) during midgestation. The main finding was that endogenous PRL and GH maintained progesterone secretion in HST heifers in a similar manner to that in SOC throughout pregnancy. Serum PRL averaged 37 vs 187 and GH 2 vs 4 ng/ml in HST heifers compared with SOC, whereas LH abruptly decreased to undetectable levels after HST compared with a modest 0.4 ng/ml in SOC heifers. The second finding was that parturition and lactation occurred in HST heifers with calf delivery induced to occur at the same time as SOC. Milk production in HST animals was severely limited, and postpartum estrus obliterated compared with SOC. The suckling stimulus sustained milk ejection in HST heifers in spite of diminished PRL, GH, thyroid stimulating hormone, thyroxine and tri-iodothyronine secretion. The results suggest that PRL, GH and possibly placental lactogen are luteotropic during pregnancy in cattle.

Animals↗
PubMed1999

Clinical significance of a cytologic diagnosis of atypical glandular cells of undetermined significance.

OBJECTIVE: To assess the clinical significance of a cytologic diagnosis of atypical glandular cells of undetermined significance (AGUS) and determine the most appropriate evaluation of these patients. STUDY DESIGN: Between 1993 and 1995, 44,217 Papanicolaou smears were evaluated at Allegheny University Hospitals, Medical College of Pennsylvania Campus. There were 108 (0.24%) cases of AGUS smears during that time. No clinical information was available for 14 patients, and 19 were lost to follow-up. The charts of the remaining 75 cases were retrospectively reviewed. RESULTS: Tissue specimens were available for 62 of the 75 patients. There were 26 (42%) with no significant histopathologic findings, 13 (21%) with polyps, 5 (8%) cases of endometrial hyperplasia, 2 (3%) with endometrial adenocarcinoma, 12 (19%) with cervical intraepithelial neoplasia (CIN), 1 (2%) with adenosquamous carcinoma of the cervix, 2 (3%) with cervical adenocarcinoma in situ and 1 (2%) case of metastatic breast cancer. The total number of patients with significant histopathology other than polyps was 23 (37%). The median age of the patients was 49 years. There were more cases of endometrial hyperplasia and endometrial cancer (19%) in women 49 years or older than in younger women; only one (3%) case of endometrial hyperplasia was detected in the younger age group (P = .057). Patients who underwent more-aggressive evaluation (colposcopy and biopsies plus endometrial sampling, cone biopsy or hysterectomy) had greater numbers of abnormal histopathologic findings (55%) than patients who underwent endometrial sampling only (21%) or those who underwent colposcopy and biopsy only (33%). This difference approaches statistical significance (P = .057). A significant proportion of patients with a history of CIN and a cytologic diagnosis of AGUS were found to have CIN (47%), while 8% of those with no history of CIN were found to have CIN (P = .002). Fifty percent of patients with a history of cancer (all had breast cancer) and AGUS had abnormal histopathology. Patients with a subclassification of AGUS "favor neoplasia" had a greater proportion of significant histopathology (72%) as compared to AGUS "unspecified" (26%) and AGUS "favor reactive" (20%) (P = .003). CONCLUSION: A significant proportion of women with a cytologic diagnosis of AGUS have abnormal histopathology. Heightened awareness should be raised in patients with AGUS and a history of CIN or cancer and in those with the AGUS subclassification "favor neoplasia."

Adolescent↗
PubMed1998

Seasonal regulation of prolactin secretion in hypophyseal stalk transected beef calves.

Seasonal regulation of prolactin secretion was investigated in crossbred beef heifer calves. Calves were randomly assigned to hypophyseal stalk transection (HST, n = 6) or sham-operation control (SOC, n = 6) groups and fitted 1 day before surgery with an indwelling external jugular catheter. Prolactin (PRL), growth hormone (GH), thyroid stimulating hormone (TSH), thyroxine (T4), and tri-iodothyronine (T3) in peripheral serum were measured by radioimmunoassay in samples obtained before and after HST or SOC. During the first 8 days after HST, PRL concentrations remained significantly greater than SOC, but then decreased in both HST and SOC calves to 4 +/- 2 (+/- SE) and 10 +/- 3 ng/ml, respectively (P < 0.001). PRL remained low in both HST and SOC groups for three months after surgery. By four months, HST calves had lower basal PRL (5 +/- 1 ng/ml) than observed in SOC (40 +/- 4 ng/ml), and seasonal changes in PRL blood concentration also were attenuated by HST. Although HST reduced PRL secretion, it did not abolish the effect of seasonal changes (P < 0.01); circulating PRL concentration increased six-fold by shifts in photoperiod and temperature from winter to summer in these stalk-transected calves. The SOC group had higher serum GH during the winter (3.8 +/- 0.8) than in July (1.3 +/- 0.03 ng/ml). The HST group had the opposite profile of GH concentration, however, with concentrations being higher during May through July. Thyroid stimulating hormone secretion was partly sustained after stalk transection possibly by negative feedback of reduced circulating thyroxine and tri-iodothyronine. These results in both hypophyseal stalk-transected and sham-operated beef calves maintained in a natural environment strongly suggest that hypothalamic regulation of PRL secretion by adenohypophyseal cells is extremely sensitive to seasonal changes throughout the year. Additionally, immediately after HST, PRL blood concentration remains significantly greater than in SOC calves but eventually decreases to low blood concentration in HST calves, and unlike that seen after HST in primates. Regardless, basal PRL serum concentration responds to seasonal changes, but a less distinct change in basal GH serum concentration in HST calves than seen in the SOC calves.

Animals↗
PubMed1998

Antiporcine relaxin (antipRLX540) treatment decreases relaxin plasma concentration and disrupts delivery in late pregnant pigs.

Antibody against porcine relaxin (antipRLX540; 1:950,000) was produced in sheep and used to determine the effect on relaxin and progesterone secretion, and on parturition in late pregnant pigs. In group 1, Yorkshire gilts with normal estrous cycles were bred on the second observed estrus and fitted with an indwelling jugular cannula and an intraperitoneal cannula on day 100 of pregnancy. Gilts were infused at 6-h intervals with antipRLX540 (n = 10) or PBS (n = 10) beginning on day 103 until parturition. From days 103 to 120, daily blood samples (10 ml) were collected for RIA of relaxin, progesterone, and prolactin. In group 2, bred gilts were randomly assigned to antipRLX540 (n = 11), relaxin (n = 5), and PBS (n = 8) treatment on days 111, 113, and 115. Blood was collected twice daily from day 108 to 120, and every 20 min on days 111, 113, and 115 beginning 60 min before treatment and continuing 180 min. Parturition in gilts given antipRLX540 occurred on day 112.7 compared with day 114.0 in relaxin-treated gilts and day 114.3 in PBS controls (P < 0.05). Duration of delivery from first to last piglet was greatly delayed in antipRLX540 gilts (240 min) compared with PBS controls ([117 min] P < 0.005). Average number of stillborns was greater in antipRLX540- than in PBS-treated controls (2.4 vs. 1.0; P < 0.05). Relaxin concentration in peripheral plasma was lower in antipRLX540-treated gilts from day 105 to 110, but on day 113 the antipRLX540-treated group had a greater relaxin peak release compared with PBS-treated animals (P < 0.05). Plasma progesterone concentrations were similar in antipRLX540- and PBS-treated gilts throughout the period of the study. In group 2, by day 113, progesterone decreased in antipRLX540-treated gilts compared with relaxin- and PBS-treated gilts. Prolactin levels were similar in both antipRLX540- and PBS-treated gilts; however, from 1 to 3 days postpartum the antipRLX540 group had higher prolactin concentration (P < 0.05). The results indicate that antipRLX540 decreased circulating plasma concentrations of unbound or free relaxin during the last 10 days of pregnancy in Yorkshire gilts. AntipRLX540 markedly increased both the duration of delivery of piglets and the average number of stillbirths in this litter-bearing species compared with PBS-treated controls. This study provides strong evidence that increasing circulating concentrations of relaxin during late pregnancy is crucial for unimpaired parturition in the pig.

Animals↗
PubMed1998

Three-dimensional lookup tables for Henschke applicator cervix treatment by HDR 192IR remote afterloading.

PURPOSE: We have generated three-dimensional (3D) lookup tables for dosimetric analysis and optimization of high-dose rate (HDR) gynecological treatments using the Henschke applicator. The new dosimetry data have been compared with two-dimensional (2D) data currently in use. The 3D dosimetry tables have been implemented in an existing cervix treatment-planning system and have been evaluated through analysis of clinical cases. METHODS AND MATERIALS: A general Monte Carlo N-Particles (MCNP) transport code was used to compute absorbed dose distributions around the intrauterine tandem and tungsten-shielded ovoid separately. The dosimetry data are represented in the x-y coordinate system for the intrauterine tandem table. The 3D table for the ovoid contains a radial dose function and an anisotropy function, as formulated in the spherical coordinate system. Absorbed dose at a spatial point is calculated by applying bilinear interpolation for the anisotropy function and linear interpolation for the radial dose function. The geometry factor for a finite line source is used. 3D dose calculations and optimization were performed for 20 treatments of 10 patients. The absorbed dose to critical structures, bladder and rectum, was compared by applying both the 2D table currently in use and the new tables. RESULTS: The new 2D table for the intrauterine tandem yields doses different by less than 10% from those with the current table. The 3D table for the shielded ovoids shows as large as a factor of 4 reduction of dose behind the shield compared with the present 2D table. This shielding effect leads to 21.6 +/- 9.3% and 20.0 +/- 6.6% dose reduction at rectum and bladder, respectively, for actual treatments. CONCLUSION: Our analysis indicates a need for patient-specific 3D dosimetry to permit more accurate dosimetric evaluation of HDR cervix treatments using shielded applicators. We have also shown that a Monte Carlo simulation code enabled us to derive the lookup tables necessary for 3D planning.

Brachytherapy↗
PubMed1998

Differential effects of dexamethasone and RU 486, an antigestagen and antiglucocorticoid, on progesterone and relaxin secretion in hysterectomized pigs with aging corpora lutea.

Pregnancy lasts about 114 days in pigs. Porcine corpora lutea produce not only progesterone but also relaxin (RLX), a peptide hormone that plays a critical role in suppressing uterine motility during pregnancy and in remodelling connective tissues in preparation for imminent parturition. Progesterone concentrations in peripheral blood remain elevated (approximately equal to 25 ng ml-1) for the major part of pregnancy and decrease just before parturition. The decrease in progesterone coincides with the peak prepartum RLX release. Glucocorticoid or antiglucocorticosteroid steroid, RU 486, administration during late pregnancy can induce parturition in the pig. Peak release of RLX and a coincident decrease of progesterone in the circulating blood can also occur in the complete absence of fetuses and uterus in the pig. The effects of glucocorticoid or antiglucocorticoidsteroid administration to such hysterectomized pigs on the secretion of RLX and progesterone were examined in this experiment. Unmated Yorkshire gilts were hysterectomized on days 6-8 (estrus = day 0) and given dexamethasone (total of 30 mg day-1; 2 times i.m. at 0800 and 1600 h) from days 110-118; control animals received vehicle injection during this period. RU 486 (4 mg kg1 body weight) was orally administered once daily (days 111-115) at 0800 h; placebo-treated controls were given the same amount of feed without the drug at this time. RLX concentrations in blood were markedly suppressed (P < 0.01) during dexamethasone treatment (3 +/- 0.9 ng ml-1; mean +/- S.E.) whereas a peak release of RLX (17 +/- 2.8 ng ml-1) occurred in the control group on day 113. In contrast, progesterone concentrations (14 +/- 2.5 ng ml-1) were unaffected by dexamethasone treatment compared with the controls (15 +/- 2.0 ng ml-1; P > 0.82). Upon withdrawal of dexamethasone on day 118, RLX plasma concentrations began to increase and peaked at 14 +/- 2.1 ng ml-1 (P < 0.01) on day 120. In contrast, the antiglucocorticosteroid given to hysterectomized pigs bearing aging corpora lutea caused a marked elevation in circulating levels of progesterone and delayed RLX release until after the end of drug treatment on day 115. Average weights of corpora lutea collected at day 12 were similar between treated and control groups (427 +/- 7 vs. 433 +/- 6 mg; P > 0.68). Results indicate that a synthetic glucocorticoid, dexamethasone, suppresses RLX secretion without causing luteolysis and such suppression is reversible; progesterone secretion remained unaffected. In contrast, the antiglucocorticoid, RU 486, raised progesterone plasma concentration and delayed RLX peak release but did not suppress it during treatment. This experiment provides further evidence that relaxin and progesterone secretion from aging corpora lutea of pigs are regulated through separate mechanisms, and adrenal glucocorticoids may be involved in such a regulation process.

Animals↗
PubMed1998

Prostaglandin F2alpha-induced luteolysis of aging corpora lutea in hysterectomized pigs.

Prostaglandins primarily of uterine origin play an important role in parturition. Hysterectomy of nongravid pigs early in the luteal phase maintains luteal function until about Day 150, whereas the duration of normal pregnancy is about 114 days. A precisely timed peak release of relaxin and coincident decrease in progesterone secretion in unmated hysterectomized gilts are similar to hormonal changes that occur a few hours before parturition. It is hypothesized that prostaglandin F2alpha (PGF2alpha) in hysterectomized pigs mimics abrupt changes in ovarian and pituitary hormone secretion seen before normal parturition and in early lactation. Unmated Yorkshire gilts were hysterectomized on Days 6-8 of a normal estrous cycle, and at 1200 h on Day 113, they were given an i.m. injection of 30 mg PGF2alpha-trihydroxymethylaminomethane (THAM) salt or PBS. None of these gilts expressed behavioral estrus immediately after PGF2alpha or vehicle treatment. On Day 113, PGF2alpha increased peak relaxin (60 ng/ml) compared with that of controls (34 ng/ml; p < 0.01), whereas progesterone decreased abruptly (4 vs. 16 ng/ml in PGF2alpha and PBS; p < 0.01). Prolactin remained at < 5 ng/ml from Day 98 to 120 in controls but peaked at 33 ng/ml immediately after PGF2alpha treatment on Day 113, and then decreased to levels similar to those of controls on Day 120. Sequential bleeding revealed an acute growth hormone release (4.5 ng/ml) immediately after PGF2alpha injection and return to basal levels (< 0.6 ng/ml) on Days 114-120. PGF2alpha induced abrupt shifts in progesterone, relaxin, prolactin, and growth hormone secretion in hysterectomized gilts that mimicked hormone changes seen in late pregnancy, parturition, and early lactation. These findings provide new insight into the role of PGF2alpha in abruptly changing hormone secretions by aging corpora lutea and the pituitary gland even in the absence of conceptuses or the uterus in the pig.

Animals↗
PubMed1998

Gonadotropin-releasing hormone secretion into third-ventricle cerebrospinal fluid of cattle: correspondence with the tonic and surge release of luteinizing hormone and its tonic inhibition by suckling and neuropeptide Y.

Objectives of the current studies were to characterize the pattern of GnRH secretion in the cerebrospinal fluid of the bovine third ventricle, determine its correspondence with the tonic and surge release of LH in ovariectomized cows, and examine the dynamics of GnRH pulse generator activity in response to known modulators of LH release (suckling; neuropeptide Y [NPY]). In ovariectomized cows, both tonic release patterns and estradiol-induced surges of GnRH and LH were highly correlated (0.95; p < 0.01). Collectively, LH pulses at the baseline began coincident with (84%) or within one sampling point after (100%) the onset of a GnRH pulse, and all estradiol-induced LH surges were accompanied by corresponding surges of GnRH. A 500- microg dose of NPY caused immediate cessation of LH pulses and lowered (p < 0.001) plasma concentrations of LH for at least 4 h. This corresponded with declines (p < 0.05) in both GnRH pulse amplitude and frequency, but GnRH pulses were completely inhibited for only 1.5-3 h. In intact, anestrous cows, GnRH pulse frequency did not differ before and 48-54 h after weaning on Day 18 postpartum, but concentrations of GnRH (p < 0.05) and amplitudes of GnRH pulses (4 of 7 cows) increased in association with weaning and heightened secretion of LH. We conclude that the study of GnRH secretory dynamics in third-ventricle CSF provides a reasonable approach for examining the activity and regulation of the hypothalamic pulse generator in adult cattle. However, data generated using this approach must be interpreted in their broadest context. Although strong neurally mediated inhibitors of LH pulsatility (suckling; NPY) had robust effects on one or more GnRH secretory characteristics in CSF, only high doses of NPY briefly abolished GnRH pulses. This implies that the GnRH signal received at the hypophyseal portal vessels under these conditions may differ quantitatively or qualitatively from those in CSF, and theoretically would be undetectable or below a biologically effective threshold when LH pulses are absent.

Animals↗
PubMed1998

Experimental and Monte Carlo dosimetry of the Henschke applicator for high dose-rate 192Ir remote afterloading.

We have performed extensive computational and experimental dosimetry of the Henschke applicator with respect to high dose-rate 192Ir brachytherapy using a GAMMAMED remote afterloader. Our goal was to generate clinically useful two- and three-dimensional look-up tables. Dose measurements of the Henschke applicator involved using TLD chips placed in a polystyrene phantom. Monte Carlo simulations were performed using the MCNP code. The computational models included the detailed geometry of 192Ir source, tandem tube, and shielded ovoid. The measured dose rates were corrected for the dependence of TLD sensitivity on the distance of measurement points from the source. Transit dose delivered during source extension to and retraction from a given dwell position was estimated by Monte Carlo simulations, and a correction was applied to the experimental values. For the applicator tandem, the ratio of dose rates obtained by MCNP to those measured by TLD chips ranges from 0.92 to 1.10 with an average of 0.98 and a standard deviation of 0.02. The measured and calculated dose rates at 1 cm on the transverse axis are 1.10 cGy U-1 h-1. For the shielded ovoid, the ratio ranges from 0.88 to 1.16 with an average of 1.00 and a standard deviation of 0.07. Causes of the discrepancy between the Monte Carlo and TLD results were identified. We found that the combined uncertainty of measured dose rates due to these causes is 5.6% for the applicator tandem and 8.4% for the shielded ovoid. Therefore, the results of the Monte Carlo simulation are considered to have been validated by the measurements within the uncertainty involved in the calculation and measurements.

Brachytherapy↗
PubMed1998

State institutions: thirty years of depopulation and closure.

Over the past 30 years, a number of social, political, and economic forces have influenced public policy decisions regarding residential services for persons with mental retardation and other developmental disabilities (MR/DD). One of the most striking outcomes of these forces has been a steady decrease of persons with MR/DD residing in state institutions. In this paper we show the changes over the past 30 years in state institutional populations, interstate variability, movement of individuals into and out of state institutions, costs of state institutional care, and state institution closures as a result of social policy.

Deinstitutionalization↗
PubMed1997

Enhancement of 131I-mediated cytotoxicity by caffeine.

In cell culture, caffeine has been shown to enhance the lethality of DNA-damaging agents including ultraviolet rays, X-irradiation, and alkylating agents. We have previously reported a Phase I clinical trial demonstrating the feasibility of intraperitoneal radioimmunotherapy in patients with refractory ovarian cancer using 131I-labeled monoclonal antibody OC125. We are now exploring the possibility of using caffeine to enhance the toxicity of 131I-irradiation in target cells. As an in vitro model we tested this hypothesis using Chinese hamster ovary (CHO) cells exposed to 131I-labeled human serum albumin at various doses (4 to 70 microCi/ml) for 24 hr followed by 24 hr of incubation with caffeine. Cytotoxicity was measured by clonogenic survival and a nuclear fragmentation assay. The results show that caffeine, at a concentration of 7.7 mM, significantly enhances the cytotoxicity of 131I-irradiation.

Animals↗
PubMed1997

5-fluorouracil iontophoretic therapy for Bowen's disease.

BACKGROUND: Topical 5-fluorouracil (5-FU) is an accepted therapy for Bowen's disease. Recurrences with this method have been attributed to deep follicular involvement and poor patient compliance because of the prolonged treatment time required. OBJECTIVE: We sought to determine whether iontophoresis of 5-FU is an effective therapy for Bowen's disease. METHODS: Twenty-six patients with biopsy-proven Bowen's disease received eight 5-FU iontophoretic treatments in 4 weeks. Local excision was done 3 months after the last treatment. The specimens were step-sectioned and evaluated for any histologic evidence of bowenoid changes. RESULTS: Only 1 of 26 patients showed histologic evidence of Bowen's disease 3 months after treatment. CONCLUSION: 5-FU iontophoresis appears to be a safe, effective, and well-tolerated therapy for Bowen's disease.

Aged↗