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Biomedical subjects

C Moretti

Publications and source records attributed to C Moretti.

At least 37 records · Page 2Linked to original sources
PubMed2000

Influence of growth hormone on a new marker of cartilage metabolism (chondrex).

The aim of this study was to evaluate the usefulness of a major secretory protein of human chondrocytes (chondrex) as a potential serum marker of bone responsiveness to growth hormone (GH). The study included 18 children (10 F, 8 M), aged 10.9 +/- 2.3 years, bone age 8.8 +/- 2.7 years, height -2.3 +/- 0.22 SDS, affected by isolated idiopathic GH deficiency (GHD). Serum samples for evaluation of chondrex, total, and bone alkaline phosphatase were taken before and 3 and 6 months following treatment with rhGH. The basal serum level of chondrex did not differ between patients (37 +/- 22 ng/ml) and controls (33 +/- 9.8 ng/ml). Following 6 months of treatment with rhGH, a significant increase of height velocity SDS (from -2.8 +/- 0.5 to 1.3 +/- 0.7), total (from 195 +/- 47 to 264 +/- 79 U/liter) and bone alkaline phosphatase (from 81 +/- 21 to 108 +/- 30 U/liter) was observed, while chondrex serum level remained unchanged (from 37 +/- 22 to 36 +/- 29 ng/ml). It was concluded that chondrex cannot be considered a reliable marker of bone responsiveness to GH in the growing child.

Adipokines↗
PubMed2000

Re-dosing of prostaglandin-E1 versus prostaglandin-E1 plus phentolamine in male erectile dysfunction: a dynamic color power Doppler study.

During penile pharmacotesting, anxiety may overcome complete smooth muscle relaxation and lead to false positive diagnosis of organic male erectile dysfunction (ED). We tested the efficacy and safety of re-dosing of PGE1 alone versus combination of PGE, and the alpha1,2-blocker phentolamine (PHE) to improve an incomplete pharmaco-induced erection during color-power-Doppler (CPD) sonography. 116 consecutive impotent patients were submitted to CPD and injected with 10 microg PGE, plus audiovisual sexual stimulation. Clinical evaluation of rigidity and CPD parameters were normal in 26 patients while in the remaining they were upgraded in 15% and 35% after redosing of 10 microg PGE1 alone and 10 microg PGE1 plus 1 mg PHE, respectively (P < 0.05); furthermore, in these latter patients CPD studies showed increased visualisation of distal ramifications of helicine arterioles. The final diagnosis was changed in those patients who responded to re-dosing with no differences in the occurrence of prolonged erections between the two treatments. We conclude that re-dosing of PGE1/PHE mixture is a safe and effective procedure to maximize erectile response during dynamic CPD sonography and has a better diagnostic sensitivity than re-dosing of PGE1 alone.

Adrenergic alpha-Antagonists↗
PubMed2000

IPEM guidelines on dosimeter systems for use as transfer instruments between the UK primary dosimetry standards laboratory (NPL) and radiotherapy centres.

United Kingdom dosimetry codes of practice have traditionally specified one electrometer for use as a secondary standard, namely the Nuclear Enterprises (NE) 2560 NPL secondary standard therapy level exposure meter. The NE2560 will become obsolete in the foreseeable future. This report provides guidelines to assist physicists following the United Kingdom dosimetry codes of practice in the selection of an electrometer to replace the NE2560 when necessary. Using an internationally accepted standard (BS EN 60731:1997) as a basis, estimated error analyses demonstrate that the uncertainty (one standard deviation) in a charge measurement associated with the NE2560 alone is approximately 0.3% under specified conditions. Following a review of manufacturers' literature, it is considered that modern electrometers should be capable of equalling this performance. Additional constructural and operational requirements not specified in the international standard but considered essential in a modern electrometer to be used as a secondary standard are presented.

Guidelines as Topic↗
PubMed2000

Mild thyroid abnormalities and recurrent spontaneous abortion: diagnostic and therapeutical approach.

PROBLEM: The aim of this study is to evaluate the role of mild thyroid abnormalities in recurrent spontaneous abortion, and to assess the effects of two different therapeutical protocols. METHOD: A prospective study in the population of recurrent aborters with mild thyroid abnormalities, evaluating the obstetric outcome in 42 patients. Sixteen thyroid autoantibodies positive patients were treated with thyroid replacement therapy, while 11 patients received intravenous immunoglobulins (IVIG). Fifteen patients, characterized by negative antithyroid antibodies, and having underlying thyroid pathology, were treated with thyroid replacement therapy. RESULTS: Among patients with thyroid antibodies, 6 out of the 11 pregnancies (54.5%) treated with IVIG ended in live birth. In the thyroid supplementation group, 13 out of 16 pregnancies (81.2%) ended in live birth. Only one pregnancy loss occurred among patients with a mild underlying thyroid pathology treated with thyroid replacement therapy. CONCLUSIONS: Mild thyroid abnormalities are associated with an increased rate of miscarriage. This poor obstetrical prognosis seems to be related to an impaired thyroid adaptation to pregnancy. Thyroid replacement therapy appears to be more effective than IVIG in preventing a new miscarriage.

Abortion, Habitual↗
PubMed2000

Pituitary adenylate cyclase-activating polypeptide (PACAP) and PACAP-receptor type 1 expression in rat and human placenta.

Pituitary adenylate cyclase-activating polypeptide (PACAP), the new hypophysiotropic factor member of the vasoactive intestinal peptide (VIP)/secretin/glucagon/GHRH family of neuropeptides, exerts its biological action by interacting with both PACAP-selective type I receptors (PAC1) and type II receptors (VPAC1), which bind both PACAP and VIP. The placenta is a site of production of hypophysiotropic factors that participate in the control of local hormone production, as well as the respective hypothalamic-pituitary neurohormones. In the present study, we show the expression of PACAP gene and irPACAP distribution within rat and human placental tissues, by means of RT-PCR and immunohystochemical experiments. In both rat and human placenta, we evaluated the expression of PAC1 gene by Northern hybridization analysis performed with a 32P-labeled 706 nt complementary DNA probe, derived from the full-length coding region of the rPAC1 complementary DNA. The results of these experiments demonstrate the presence, in both human and rat placenta, of a 7.5-kb transcript similar in size to those detected in the ovary, brain, and hypothalamus. Alternative splicing of two exons occurs in human and rat PAC1 gene generating splice variants with variable tissue-specific expression. To ascertain which of the splice variants were expressed in placental tissue we performed RT-nested PCR using primers flanking the insertion sequence termed hip/hop cassette in rat or SV1/SV2 box in human gene. Electrophoretic analysis of the PCR products showed a different pattern of expression of messenger RNA splicing variants in human and rat placenta. In particular, the rat placenta expresses the short PAC1 receptor (PAC1short), the rPAC1-hip or hop (which are indistinguishable with the primers used), and the rPAC1-hip-hop, whereas the human placenta expresses only the PAC1SV1 (or SV2) variant, structurally homologous to the rat PAC1 hip (or hop). Sequence analysis of the human PCR-amplified PAC1 variant was therefore carried out and revealed that human placenta only expresses the PAC1SV2 isoform. The presence and characterization of PACAP binding sites was then investigated in human placenta by radioligand binding studies performed on crude membrane preparation using [125I]PACAP27 as tracer. Scatchard analysis of the binding results revealed the presence of two binding sites, one with high affinity and low capacity (Kd 0.33+/-0.04 nM; Bmax 36.9+/-12.1 fmol/mg protein) and one with low affinity and high capacity (Kd 24+/-6.9 nM, Bmax 9.3+/-0.19 pmol/mg protein). The relative potencies of PACAP-related peptides for inhibition ofradioligand binding were: PACAP27 > or = PACAP38 > VIP, whereas GHRH and other unrelated peptides, such as CRH and beta-endorphin, did not inhibit [125I]PACAP27 binding. In conclusion, in this study, we provide evidence for the expression of PACAP within rat and human placenta. We also demonstrate that both human and rat placenta express the PAC1 gene and that the human tissue has binding sites for PACAP. These findings may suggest a role for PACAP in the regulation of placental physiology through autocrine and/or paracrine mechanisms.

Animals↗
PubMed2000

Leptin and aging: correlation with endocrine changes in male and female healthy adult populations of different body weights.

Aging is associated with changes in plasma levels of several hormones. There are conflicting reports on whether circulating leptin levels change during aging, the possible explanation for which is that alterations in adiposity and body mass index (BMI) also occur. In this study we measured plasma leptin and other hormonal parameters known to influence leptin in 150 men and 320 women of a wide age (18-77 yr) and BMI (18.5-61.1 kg/m2) range. Subjects of each gender were separated into 2 groups of similar BMI, i.e. nonobese (BMI, <30) and obese (BMI, >30), and treated separately. Statistical analysis was performed, treating each group of subjects as a whole population or divided into age groups (<30, 30-50, and >50 yr). BMI-adjusted leptin levels were progressively lower with increasing age in women, with a consistent fall after menopause (-21%; P < 0.001); in men, leptin levels also tended to be lower in subjects more than 50 yr of age, but the reduction was not significant. Multiple linear regression analysis, performed on subjects treated either as a whole population or divided into obese and nonobese, showed that in both genders BMI and age were independent contributors of leptin levels, and there was an inverse relationship between leptin and age in both obese (standardized coefficient beta = -0.25 in women and -0.23 in men; P < 0.01) and nonobese (-0.22 in women and -0.20 in men; P < 0.05) subjects. The correlation of leptin and age with plasma levels of sex and thyroid hormones, GH, insulin-like growth factor I, PRL, and insulin was also evaluated. The variables that correlated with leptin were included in a multiple regression model that included BMI and age. Testosterone in men (-0.43 in nonobese and -0.19 in obese; P < 0.05) and estradiol in women (0.22 in nonobese and 0.24 in obese; P < 0.05) were important contributors to leptin levels; also, dehydroepiandrosterone sulfate in obese women (-0.16) and sex hormone-binding globulin in obese subjects of both genders (0.15 in women and 0.19 in men) were significant determinants in the model. However, none of the hormonal parameters abolished the negative correlation between leptin and age or the gender difference in leptin levels. In conclusion, our data show that in adult humans of different body weight, serum leptin gradually declines during aging; leptin reduction is higher in women than in men, but it is independent from BMI and other age-related endocrine changes.

Adolescent↗
PubMed2000

Novel point mutation in the splice donor site of exon-intron junction 6 of the androgen receptor gene in a patient with partial androgen insensitivity syndrome.

Androgen receptor (AR) gene mutations have been shown to cause androgen insensitivity syndrome with altered sexual differentiation in XY individuals, ranging from a partial insensitivity with male phenotype and azoospermia to a complete insensitivity with female phenotype and the absence of pubic and axillary sexual hair after puberty. In this study we present an 11-yr-old XY girl, with clinical manifestations peculiar for impaired androgen biological action, including female phenotype, blind-ending vagina, small degree of posterior labial fusion, and absence of uterus, fallopian tubes, and ovaries. At the time of the diagnosis the patient had a FSH/LH ratio according to the puberal stage, undetectable 17beta-estradiol, and high levels of testosterone (80.1 ng/mL). After bilateral gonadectomy, performed at the age of 11 yr, histological examination showed small embryonic seminiferous tubules containing prevalently Sertoli cells and occasional spermatogonia together with abundant fibrous tissue. Molecular study of the patient showed a guanine to thymine transversion in position +5 of the donor splice site in the junction between exon 6 and intron 6 of the AR gene. The result of RT-PCR amplification of the AR messenger ribonucleic acid from cultured genital skin fibroblasts of the patient suggests that splicing is defective, and intron 6 is retained in most of the receptor messenger ribonucleic acid molecules. We show by immunoblotting that most of the expressed protein lacks part of the C-terminal hormone-binding domain, and a small amount of normal receptor is observed. This is probably responsible for the reduced binding capacity in genital skin fibroblasts of the patient. The molecular basis of the alteration in this case is a novel, uncommon mutation, leading to a phenotype indicative of a partial androgen insensitivity syndrome, Quigley's grade 5.

Androgen-Insensitivity Syndrome↗
PubMed1999

Cloning and expression analysis of a Petunia hybrida flower specific mitotic-like cyclin.

A cyclin cDNA clone (Pethy;CycB1;1) was isolated from a Petunia hybrida ovary specific cDNA library. Sequence comparison revealed that Pethy;CYCB1;1 protein is highly homologous to mitotic B1 cyclins. Northern analysis and in situ hybridisation experiments showed that its expression is developmentally regulated and restricted to flower organs. We have attempted to define some of the cell division patterns which contribute to shaping each floral organ by analysing Pethy;CycB1;1 expression on Petunia flower sections. While in sepals, epidermis and parenchyma cell division patterns were comparable, there were two distinct cell division patterns in petals. In the epidermis, Pethy;CYCB1;1 expression was found both at the petal tip and along epidermis, whereas in the parenchyma only at the petal tips. In reproductive organs cell divisions were detected only in sporophytic tissues. No signals were detected inside meiotic cells.

Cloning, Molecular↗
PubMed1999

Significance of T-wave changes during early dobutamine stress echocardiography in patients with Q-wave acute myocardial infarction.

The relation between T-wave changes and regional contraction during dobutamine stress echocardiography at low (5 to 10 microg/kg/min) and high (20 to 40 microg/kg/min) doses in 43 consecutive patients, early (7+/-2 days) after first recent Q-wave acute myocardial infarction has been evaluated. T-wave changes detected in > or =2 infarct-related electrocardiographic leads during dobutamine infusion were defined as follow: (1) negative T waves becoming positive, (2) positive T waves becoming upright > or =2 mm, and (3) negative T waves becoming upright > or =2 mm from baseline. Wall motion score index (WMSI) was defined as the sum of the echocardiographic scores of 16 segments divided by total segments considered at baseline, and at low and peak doses of dobutamine. Patients were classified according to the absence or presence of dobutamine T-wave changes. Those without T-wave changes had a significantly higher WMSI at rest (1.68+/-0.23 vs 1.50+/-0.21; p <0.05) and at peak (1.77+/-0.34 vs 1.51+/-.30 p <0.05) of dobutamine stress testing, without higher incidence of viability, homozonal, and heterozonal ischemia and chest pain. The angiographic patterns were similar between groups. Regression analysis showed a significant correlation between WMSI and T-wave amplitude at baseline (R = 0.38, p = 0.01) and at peak dobutamine stress testing (R = 0.50, p = 0.0006). The sensitivity sensitivity, specificity, and accuracy of T-wave changes to detect myocardial viability were 0.27, 0.84, and 0.70, respectively. The sensitivity, specificity, and accuracy of T-wave changes to detect homozonal ischemia were 0.76, 0.27, and 0.46, respectively. In conclusion, dobutamine-induced T-wave changes are associated with a greater extent of wall motion abnormalities both at rest and at peak stress echocardiography, but they are of little value in predicting myocardial viability when analyzed early after myocardial infarction.

Adult↗
PubMed1999

Body-fat distribution and responsiveness of the pituitary-adrenal axis to corticotropin-releasing-hormone stimulation in sedentary and exercising women.

Excess upper-body (android) fat is considered an health hazard. Exercise training is known to have the potential to modify body composition and to induce a preferential loss of abdominal fat. We studied and compared the composition of whole body and major body regions using dual-energy X-ray absorptiometry (DEXA) in 21 exercising (3-4 hours of intense physical activity/day) and 21 sedentary eumenorrhoic women of similar ages, body mass index (BMI), waist-to-hip ratio (WHR) and age of menarche. In a small number of women in each group (6 out of 21), the ACTH and cortisol response to CRH test and the 24-h urinary cortisol excretion was evaluated. Exercising women had 10% higher total and leg lean mass (p<0.05), and 38% lower total fat mass (p<0.01) than sedentary women. Furthermore, the proportion of android fat was 22% lower in exercising than sedentary women (p<0.01), while the proportion of lower-body (gynoid fat) was unchanged. BMI and WHR were not different between the two groups, while the android/gynoid fat ratios were 16% lower in exercising than in sedentary women (p<0.01). In the exercising women, ACTH and cortisol plasma levels, as well as the 24-h urinary cortisol excretion, were significantly (p<0.01) higher than in the sedentary women studied. In these subjects, a direct relationship between the peak delta percentage increases of ACTH and cortisol after the CRH test and the proportion of android fat was found (r=0.60, p<0.05 and r=0.69, p<0.02, respectively). These results demonstrate that in women who practise intense exercise there are significant differences in body fat distribution in comparison to sedentary women, with a marked less amount of android fat, and suggest that this difference may be related to a reduced response of the pituitary-adrenal axis to CRH.

Absorptiometry, Photon↗
PubMed1999

Comparing the effects of nasal synchronized intermittent positive pressure ventilation (nSIPPV) and nasal continuous positive airway pressure (nCPAP) after extubation in very low birth weight infants.

In this study we hypothesized that nasal synchronized intermittent positive pressure ventilation (nSIPPV) would provide more ventilatory support than nasal continuous positive airway pressure (nCPAP) in the immediate post-extubation period in very low birth weight (VLBW) infants. We tested this hypothesis by comparing the effects of these two ventilatory techniques on ventilation, gas exchange, and patient inspiratory effort in 11 preterm infants immediately after extubation. All neonates studied (BW: 1141+/-(SEM) 53 g; GA: 28.1+/-(SEM) 0.5 wks) had received mechanical ventilation because of respiratory distress at birth and were extubated by day 14 of life. Nasal SIPPV and nCPAP were applied in random order to each infant after extubation so that each was his/her own control. Both nCPAP and nSIPPV were delivered at end-expiratory pressures (PEEP) of 3 cm H2O. Inspiratory times (Ti) and peak inspiratory pressures set during nSIPPV were the same as those used at the time of extubation. Recordings lasted 45 min in each mode of ventilation. Tidal volume (Vt), minute volume (Ve), respiratory rate (RR), airway pressure (Paw), transcutaneous PO2 (TcPO2) and PCO2 (TcPCO2) as well as phasic esophageal pressure deflections (Pe), as an estimate of inspiratory effort, were measured. The measurements obtained during both modes of ventilation indicated significant differences between the two techniques. Indeed, application of nSIPPV was associated with a statistically significant increase in Vt and Ve. In addition, Pe decreased by 30% during nSIPPV (P<0.01). TcPCO2 was statistically significantly lower during nSIPPV than nCPAP, and RR as well. These data therefore suggest that nSIPPV may provide more ventilatory support than nCPAP in the post-extubation period with less patient inspiratory effort.

Humans↗
PubMed1999

Expression of functional leptin receptors in rodent Leydig cells.

Several studies indicate that the size of body fat stores and the circulating levels of the adipocyte-derived hormone leptin are able to influence the activity of the hypothalamic-pituitary-gonadal axis. The leptin-hypothalamic-pituitary-gonadal interactions have been mainly studied at the level of the central nervous system. In this study, we investigated the possibility that leptin may have direct effects on the rodent Leydig cell function. To probe this hypothesis, we first analyzed the expression of leptin receptors (OB-R) in rodent Leydig cells in culture. RT-PCR studies showed that rat Leydig cells express both the long (OB-Rb) and short isoform (OB-Ra) of leptin receptor, whereas MLTC-1 cells (a murine Leydig tumor cell line) express only the long isoform. Short-term (30-90 min) incubation of rat Leydig cells with increasing concentrations ofleptin (2-500 ng/ml) led to a significant and dose-dependent inhibition of human (h)CG-stimulated testosterone (T) production (approximately 60% reduction, IC50 = 20 ng/ml) but no change in basal androgen release. Also, leptin (150 ng/ml) amplified hCG-induced intracellular cAMP formation (1- to 2-fold) without modifying basal cAMP levels. Subsequent experiments showed that leptin inhibited 8Br-cAMP-stimulated T production, indicating that leptin's effect is exerted beyond cAMP. The inhibitory effect of leptin on hCG-induced T secretion was accompanied by a significant reduction of androstenedione and a concomitant rise of the precursor metabolites pregnenolone, progesterone, and 17-OH-progesterone, conceivable with a leptin-induced lesion of 17,20 lyase activity. Separate experiments performed with the MLTC-1 cells (not expressing cytochrome P450-17alpha) showed that leptin, though amplifying hCG-stimulated cAMP production, did not modify hCG-stimulated pregnenolone and progesterone release. These results further indicate that leptin action on steroidogenesis occurs downstream of progesterone synthesis. Northern Blot experiments showed no acute effect of leptin on cytochrome P450-17alpha messenger RNA accumulation in rat Leydig cells in basal and hCG-stimulated conditions, excluding that the rapid changes observed were caused by messenger RNA degradation. In conclusion, these findings, for the first time, show that leptin has direct, receptor-mediated actions on rodent Leydig cells in culture, at concentrations within the range of obese men.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1999

Thyroid hormone effects on mouse oocyte maturation and granulosa cell aromatase activity.

In the present study we evaluated the role of T3 on the in vitro processes of mouse cumulus cell-oocyte complex expansion, oocyte meiotic maturation, and granulosa cell aromatase activity. Results obtained from cumuli oophori isolated from immature and adult mice ovaries demonstrated that T3 at all concentrations tested (0.1-100 nM) did not affect basal or FSH-induced cumulus expansion or interfere with oocyte meiotic maturation up to metaphase II stage. On the contrary, T3 inhibited in a time- and dose-dependent manner FSH-induced aromatase activity in cultured granulosa cells obtained from either adult or immature female mice. The half-maximal dose (ED50) of T3 inhibition was 0.87 +/- 0.21 nM, which is in agreement with the reported dissociation constant of T3 nuclear receptor (Kd = 0.4-5 nM) in mammalian granulosa cells. Time-course experiments demonstrated higher sensitivity to T3 of adult granulosa cells with respect to immature granulosa cells in culture. Indeed, in immature granulosa cells T3 inhibition became significantly evident only after 6 days of hormonal treatment, whereas in adult granulosa cells the inhibitory effect was present after only 2 days of treatment. (Bu)2cAMP- or 3-isobutyl-1-methyl-xanthine-stimulated aromatase activity was also significantly decreased by T3, thus suggesting that the inhibition was downstream from cAMP formation. Lastly, analysis of aromatase messenger RNA (mRNA) levels by semiquantitative RT-PCR demonstrated the ability of FSH to increase aromatase mRNA level in cultured granulosa cells by 2.4 +/- 0.5-fold. In agreement with the effect on enzyme activity, the stimulatory effect of FSH on aromatase mRNA level was greatly reduced after T3 cotreatment. In conclusion, T3 inhibition of aromatase activity may be of physiological relevance in the complex multihormonal regulation of mammalian follicle development and may contribute to explaining the alteration in female reproductive functions after thyroid hormone hypo- or hypersecretion.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Leptin and androgens in male obesity: evidence for leptin contribution to reduced androgen levels.

Leptin circulates in plasma at concentrations that parallel the amount of fat reserves. In obese males, androgen levels decline in proportion to the degree of obesity. Recently, we have shown that in rodent Leydig cells leptin inhibits hCG-stimulated testosterone (T) production via a functional leptin receptor isoform; others have found that leptin inhibits basal and hCG-induced T secretion by testis from adult rats. In this study, we further investigated the relationship linking leptin and androgens in men. Basal and hCG-stimulated leptin and sex hormone levels were studied in a large group of men ranging from normal weight to very obese (body mass index, 21.8-55.7). Initial cross-sectional studies showed that circulating leptin and fat mass (FM) were inversely related with total and free T (r = -0.51 and r = -0.38, P < 0.01 and P < 0.05, respectively). Multiple regression analysis indicated that the correlation between leptin or FM and T was not lost after controlling for SHBG and/or LH and/or estradiol (E2) levels and that leptin was the best hormonal predictor of the lower androgen levels in obesity. Dynamic studies showed that in obese men the area under the curve of T and free T to LH/hCG stimulation (5000 IU i.m.) was 30-40% lower than in controls and inversely correlated with leptin levels (r = -0.45 and r = -0.40, P < 0.01 and P < 0.05, respectively). Also, LH/hCG-stimulation caused higher increases in 17-OH-progesterone to T ratio in obese men than in controls, whereas no differences were observed between groups either in stimulated E2 levels or in the E2/T ratio. In all subjects, the percentage increases from baseline in the 17-OH-progesterone to T ratio were directly correlated with leptin levels or FM (r = 0.40 and r = 0.45, P < 0.01), but not with E2 or other hormonal variables. In conclusion, our studies, together with previous in vitro findings, indicate that excess of circulating leptin may be an important contributor to the development of reduced androgens in male obesity.

17-alpha-Hydroxyprogesterone↗
PubMed1998

A novel antiprotozoal aminosteroid from Saracha punctata.

A new aminosteroid, 3beta-amino-22,26-epiminocholest-5-ene named sarachine (1), and two known flavonoids, eriodictyol (2) and 7-O-beta-D-glucopyranosyl-eriodictyol (3), were isolated from the leaves of Saracha punctata. The alkaloid was found to inhibit the growth of Leishmania braziliensis promastigotes (100% at 25 microM) and of Trypanosoma cruzi epimastigotes in culture (50% at 25 microM) and showed a strong in vitro antiplasmodial activity with an IC50 of 25 nM.

Animals↗
PubMed1998

Comparison of two methods of therapy level calibration at 60Co gamma beams.

The accuracy and traceability of the calibration of radiotherapy dosimeters is of great concern to those involved in the delivery of radiotherapy. It has been proposed that calibration should be carried out directly in terms of absorbed dose to water, instead of using the conventional and widely applied quantity of air kerma. In this study, the faithfulness in disseminating standards of both air kerma and absorbed dose to water were evaluated, through comparison of both types of calibration for three types of commonly used radiotherapy dosimeters at 60Co gamma beams at a few secondary and primary standard dosimetry laboratories (SSDLs and PSDLs). A supplementary aim was to demonstrate the impact which the change in the method of calibration would have on clinical dose measurements at the reference point. Within the estimated uncertainties, both the air kerma and absorbed dose to water calibration factors obtained at different laboratories were regarded as consistent. As might be expected, between the SSDLs traceable to the same PSDL the observed differences were smaller (less than 0.5%) than between PSDLs or SSDLs traceable to different PSDLs (up to 1.5%). This can mainly be attributed to the reported differences between the primary standards. The calibration factors obtained by the two methods differed by up to about 1.5% depending on the primary standards involved and on the parameters of calculation used for 60Co gamma radiation. It is concluded that this discrepancy should be settled before the new method of calibration at 60Co gamma beams in terms of absorbed dose to water is taken into routine use.

Air↗