RESUMEN
PURPOSE: Achieving endocrine remission by gross total resection is challenging in pituitary neuroendocrine tumours (PitNETs) with cavernous sinus invasion. This study aims to assess the safety, feasibility, and optimal dose for intraoperative fluorescence imaging as an added instrument to discriminate PitNET from surrounding tissue using bevacizumab-800CW, targeting vascular endothelial growth factor A (VEGF-A). METHODS: In part I, dose-escalation (0-4â5-10-25 mg) was performed in 4 groups of 3 patients with PitNETs Knosp grade 3-4. In part II, after interim analysis, the 10 mg and 25 mg groups were expanded to a total of 6 patients. Quantitative fluoroscence molecular endoscopy consisted of wide field fluorescence molecular endoscopy and multi-diameter single fiber reflectance / single fiber fluorescence spectroscopy. Mean fluorescence intensity (MFI) of the fresh surgical specimen was calculated and VEGF-staining was performed. RESULTS: Eighteen patients were included. All doses were well tolerated. Three serious adverse events were registered, but none were tracer-related. Part I showed an adequate in-vivo tumour-to-background ratio for both 10 mg (TBR 2â00 [1â86, 2â19]) and 25 mg (TBR 2â10, [1â86, 2â58]). Part II revealed a substantially higher MFI in the 25 mg group. With both 10 mg and 25 mg a statistically significant difference between tumour and surrounding tissue was detected (p < 0â0001). All surgical specimens had VEGF-A expression. CONCLUSION: This study demonstrates the safety and feasibility of quantitative fluorescence molecular endoscopy during PitNET surgery. Both 10 mg and 25 mg bevacizumab-800CW result in clear differentiation in-vivo, with improved contrast ex-vivo (MFI) in the 25 mg group. TRIAL REGISTRATION: NCT04212793 / Study Details| Detection of PitNET Tissue During TSS Using Bevacizumab800CW| ClinicalTrials.gov.
RESUMEN
Multidiameter single fiber reflectance (MDSFR) spectroscopy is a method that allows the quantification of µs' and the phase-function-dependent parameter γ of a turbid medium by utilizing multiple fibers with different diameters. We have previously introduced the theory behind MDSFR and its limitations, and here we present an experimental validation of this method based on phantoms containing a fractal distribution of polystyrene spheres both in the absence and presence of the absorber Evans Blue.
Asunto(s)
Dispersión de Radiación , Análisis Espectral , Fractales , Fenómenos Ópticos , Fantasmas de Imagen , Poliestirenos , Reproducibilidad de los ResultadosRESUMEN
BACKGROUND: Vitamin B12 and homocysteine have been shown to be associated with depression or depressive symptoms, but the relationship has not been universal. Both vitamin B12 and homocysteine may exert an effect via vascular mechanisms; it is possible that other mechanisms apply. Holotranscobalamin is a novel, more accurate measure of tissue vitamin B12. OBJECTIVES: To examine associations between vitamin B12, serum folate, holotranscobalamin, homocysteine and depressive symptoms in a sample of healthy elderly. METHODS: Cross-sectional, observational community based study. RESULTS: Lower levels of holotranscobalamin and vitamin B12 were associated with higher levels of depressive symptoms when controlled for Mini-mental state examination scores and psychosocial and cardiovascular risk factors. Homocysteine was not associated with depressive symptoms when biological and psychosocial covariates were included. CONCLUSIONS: It is possible that low levels of vitamin B12 or holotranscobalamin are associated with depressive symptoms via mechanisms other than vascular pathology.
Asunto(s)
Trastorno Depresivo/sangre , Homocisteína/sangre , Transcobalaminas/análisis , Vitamina B 12/sangre , Anciano , Anciano de 80 o más Años , Biomarcadores/sangre , Estudios de Cohortes , Trastorno Depresivo/epidemiología , Trastorno Depresivo/psicología , Femenino , Humanos , Masculino , Irlanda del Norte/epidemiología , Satisfacción Personal , Estudios Prospectivos , Población UrbanaRESUMEN
Rational design based on a pharmacophore of CCR2 antagonists reported in the literature identified lead compound 9a with potent inhibitory activity against human CCR2 (hCCR2) but moderate activity against murine CCR2 (mCCR2). Modification on 9a led to the discovery of a potent CCR2 antagonist 21 (INCB3344) with IC(50) values of 5.1 nM (hCCR2) and 9.5 nM (mCCR2) in binding antagonism and 3.8 nM (hCCR2) and 7.8 nM (mCCR2) in antagonism of chemotaxis activity. INCB3344 exhibited >100-fold selectivity over other homologous chemokine receptors, a free fraction of 24% in human serum and 15% in mouse serum, and an oral bioavailability of 47% in mice, suitable as a tool compound for target validation in rodent models.
Asunto(s)
Pirrolidinas/química , Receptores CCR2/antagonistas & inhibidores , Administración Oral , Animales , Evaluación Preclínica de Medicamentos , Humanos , Ratones , Unión Proteica , Pirrolidinas/síntesis química , Pirrolidinas/farmacocinética , Ratas , Receptores CCR2/metabolismo , Relación Estructura-ActividadRESUMEN
The aim of this review was to describe briefly the mechanism and history of photodynamic therapy (PDT). The achieved preclinical and clinical results in Rotterdam are discussed in the light of a search to optimize aminolevulinic acid-photodynamic therapy (ALA-PDT). As the incidence of skin cancer is rising, an optimized treatment in non-melanoma skin cancer is needed.
Asunto(s)
Ácido Aminolevulínico/uso terapéutico , Fotoquimioterapia , Fármacos Fotosensibilizantes/uso terapéutico , Neoplasias Cutáneas/tratamiento farmacológico , Ensayos Clínicos como Asunto , Evaluación Preclínica de Medicamentos , HumanosRESUMEN
A novel technique of measuring the prompt, thermally induced wave-front aberrations in a large aperture flash-lamp pumped Nd3+ glass disk amplifier is presented. Implementing a 2 × 2 lens array and a 2 × 2 position sensitive detector array as a diagnostic system, the wave-front profile was successfully reconstructed for the first five Zernike terms for a temporal window of 8.5 ms.
RESUMEN
INTRODUCTION: An increase in detection of early-stage asymptomatic lung tumors could increase the overall survival rate of lung cancer patients. A new approach to cancer (pre-)screening focusses on detecting field cancerization instead of the tumor itself. The objective of this study was to investigate the use of optical spectroscopy to detect field cancerization in the buccal mucosa of lung cancer patients. METHODS: Optical buccal mucosa measurements were performed in lung cancer patients and controls using multidiameter single-fiber reflectance spectroscopy. We analyzed whether the measured optical parameters could distinguish lung cancer patients from controls. RESULTS: Twenty-three lung cancer patients, 24 chronic obstructive pulmonary disease (COPD) control patients, and 36 non-COPD controls were included. The majority of tumors were non-small-cell lung carcinomas (96%) and classified as stage I (48%). The tissue scattering properties µs' and γ at 800 nm and the tissue bilirubin concentration were all near-significantly different (P=.072, 0.058, and 0.060, respectively) between the lung cancer and COPD group. µs' at 800 nm had a sensitivity of 74% and a specificity of 63%. The microvascular blood oxygen saturation of the lung cancer patients was also higher than the COPD patients (78% vs. 62%, P=.002), this is probably a consequence of the systemic effect of COPD. CONCLUSIONS: We have demonstrated that µs' at 800 nm is increased in the buccal mucosa of patients with lung cancer compared to controls with COPD. This might be an indication of field cancerization in the oral cavity of patients with lung cancer.
RESUMEN
We present a review of six clinical studies investigating the use of photodynamic therapy (PDT) using porphyrin precursors for the treatment of Old World cutaneous leishmaniasis (CL). Thirty-nine patients with a total of 77 lesions received PDT using a range of treatment schedules following topical application of aminolevulinic acid (ALA) or methyl-aminolevulinate (MAL). The tissue response to PDT is accompanied by a mild burning sensation, erythema and reversible hypo- and hyperpigmentation. Few mechanistic studies have addressed the principles underlying the use of PDT for CL. All six reviewed papers suggest that PDT with porphyrin precursors is relatively effective in treating CL. Data are still limited, and PDT cannot at this point be recommended in routine clinical practice. The mechanism of action of this promising therapeutic modality needs to investigated further and additional controlled trials need to be performed.
Asunto(s)
Leishmaniasis Cutánea/tratamiento farmacológico , Fotoquimioterapia/métodos , Ácido Aminolevulínico/análogos & derivados , Ácido Aminolevulínico/uso terapéutico , Humanos , Fármacos Fotosensibilizantes/uso terapéutico , Porfirinas/uso terapéuticoRESUMEN
BACKGROUND: Photodynamic therapy (PDT) is an accepted treatment for superficial basal cel carcinoma (sBCC) and Bowens disease. In Rotterdam, extensive preclinical research has lead to an optimized twofold illumination scheme for aminolevulinic acid-PDT (ALA-PDT). OBJECTIVE: To provide additional evidence of ALA-PDT for sBCC, Bowens disease (BD), nodular BCC (nBCC) and actinic keratosis (AK) using a 2-fold illumination scheme after a single application of ALA. METHODS: Five hundred fifty-two lesions (430 sBCC, 20 nBCC, 32 BD, 70 AK) were treated with ALA-PDT using a twofold illumination scheme. ALA was applied topically for 4 h. Lesions were treated with two light fractions of 20 and 80 J/cm(2) separated by a 2-h dark interval. RESULTS: After a minimum follow-up of 12 months, in average follow-up of 2 years, an overall complete response of 95% was seen for all lesions. For sBCC, the complete response at 2 years was 97% (for AK 98%, for BD 84% and for nBCC 80% after 2 years). A sub-analysis of the results of lesions larger than 2 cm showed CR at 2 years of 89% for all lesions (n = 57). Cosmetic outcome was good to excellent in 95% of the treated lesions. CONCLUSION: ALA-PDT using a twofold illumination scheme of 20 plus 80 J/cm(2) separated by a 2-h dark interval leads to high complete response rates at 2 years and can be regarded as an evidence-based treatment modality for superficial growing non-melanoma skin cancer and the (pre)malignant AK. The Rotterdam fractionated approach should be included in future guidelines.
Asunto(s)
Ácido Aminolevulínico/uso terapéutico , Enfermedad de Bowen/tratamiento farmacológico , Carcinoma Basocelular/tratamiento farmacológico , Queratosis/tratamiento farmacológico , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/uso terapéutico , Neoplasias Cutáneas/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Resultado del TratamientoRESUMEN
The femoral head-neck alpha angle is used to quantify the degree of femoral head asphericity in patients suspected of cam-type femoroacetabular impingement. The measurement was first performed using magnetic resonance imaging and, more recently, three-dimensional computed tomography (CT). We set out to determine whether the alpha angle could be reliably measured using ultrasound. Patients were recruited from a cohort presenting for CT of the hip. Alpha angles were calculated following the departmental protocol by institutionally accredited radiographers. After the CT, patients were imaged with ultrasound and the alpha angle calculated from the ultrasound image by a sonographer blinded to the CT result. Statistical comparison of the two methods was performed with the Bland-Altman test using SPSS (version 21.0, Chicago, USA), and a p < 0.05 afforded significance. Twenty-eight patients were recruited. Eleven patients were bilateral examinations, providing 39 hips for analysis. There were 15 females and 13 males, with 21 right and 18 left hips examined. Average patient age (±standard deviation) was 40 y (±13.9 y). Mean (±standard deviation) measurements for CT and ultrasound were 62.5° (±14.2°) and 64.5° (±12.6°), respectively. The mean absolute difference between the two methods was 10.5° (95% confidence interval 6.9°-14.0°). Sensitivity of each individual ultrasound measurement was 91.3%. The specificity of ultrasound was 43.75%. The positive predictive value was 0.7, and the negative predictive value was 0.78. Overall accuracy of the ultrasound-derived alpha angle was calculated at 0.718. Ultrasound demonstrates good sensitivity and good negative predictive value in calculation of the femoral head-neck alpha angle compared with CT; however, specificity is low. Ultrasound measurement of the alpha angle can provide objective evidence of cam-type femoroacetabular impingement in symptomatic patients and can direct patients to more established imaging techniques where appropriate.
Asunto(s)
Pinzamiento Femoroacetabular/diagnóstico por imagen , Cabeza Femoral/diagnóstico por imagen , Cuello Femoral/diagnóstico por imagen , Ultrasonografía/métodos , Adulto , Femenino , Cabeza Femoral/patología , Cuello Femoral/patología , Articulación de la Cadera/diagnóstico por imagen , Articulación de la Cadera/patología , Humanos , Masculino , Rango del Movimiento Articular , Sensibilidad y EspecificidadRESUMEN
The objective of this study was to evaluate the performance of a dedicated light applicator for light delivery and fluence rate monitoring during Foscan-mediated photodynamic therapy of nasopharyngeal carcinoma in a clinical phase I/II study. We have developed a flexible silicone applicator that can be inserted through the mouth and fixed in the nasopharyngeal cavity. Three isotropic fibers, for measuring of the fluence (rate) during therapy, were located within the nasopharyngeal tumor target area and one was manually positioned to monitor structures at risk in the shielded area. A flexible black silicon patch tailored to the patient's anatomy is attached to the applicator to shield the soft palate and oral cavity from the 652-nm laser light. Fourteen patients were included in the study, resulting in 26 fluence rate measurements in the risk volume (two failures). We observed a systematic reduction in fluence rate during therapy in 20 out of 26 illuminations, which may be related to photodynamic therapy-induced increased blood content, decreased oxygenation, or reduced scattering. Our findings demonstrate that the applicator was easily inserted into the nasopharynx. The average light distribution in the target area was reasonably uniform over the length of the applicator, thus giving an acceptably homogeneous illumination throughout the cavity. Shielding of the risk area was adequate. Large interpatient variations in fluence rate stress the need for in vivo dosimetry. This enables corrections to be made for differences in optical properties and geometry resulting in comparable amounts of light available for Foscan absorption.
Asunto(s)
Iluminación/instrumentación , Mesoporfirinas/uso terapéutico , Neoplasias Nasofaríngeas/tratamiento farmacológico , Recurrencia Local de Neoplasia/tratamiento farmacológico , Fotoquimioterapia/instrumentación , Adolescente , Adulto , Diseño de Equipo , Análisis de Falla de Equipo , Femenino , Humanos , Indonesia , Luz , Masculino , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/uso terapéutico , Proyectos Piloto , Dosis de Radiación , Radiometría , Resultado del TratamientoRESUMEN
We have previously shown that light fractionation during topical aminolevulinic acid based photodynamic therapy (ALA-PDT) with a dark interval of 2h leads to a significant increase in efficacy in both pre-clinical and clinical PDT. However this fractionated illumination scheme required an extended overall treatment time. Therefore we investigated the relationship between the dark interval and PDT response with the aim of reducing the overall treatment time without reducing the efficacy. Five groups of mice were treated with ALA-PDT using a single light fraction or the two-fold illumination scheme with a dark interval of 30 min, 1, 1.5 and 2h. Protoporphyrin IX fluorescence kinetics were monitored during illumination. Visual skin response was monitored in the first seven days after PDT and assessed as PDT response. The PDT response decreases with decreasing length of the dark interval. Only the dark interval of 2h showed significantly more damage compared to all the other dark intervals investigated (P<0.05 compared to 1.5h and P<0.01 compared to 1h, 30 min and a single illumination). No relationship could be shown between the utilized PpIX fluorescence during the two-fold illumination and the PDT response. The rate of photobleaching was comparable for the first and the second light fraction and not dependent of the length of dark interval used. We conclude that in the skin of the hairless mouse the dark interval cannot be reduced below 2h without a significant reduction in PDT efficacy.
Asunto(s)
Ácido Aminolevulínico/farmacología , Fotoblanqueo/efectos de la radiación , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/farmacología , Animales , Fluorescencia , Cinética , Ratones , Ratones Desnudos , Fotoblanqueo/efectos de los fármacos , Fotoperiodo , Protoporfirinas/análisisRESUMEN
We have studied different single and fractionated illumination schemes after systemic administration of 5-aminolevulinic acid (ALA) to Improve the response of nodular tumors to ALA-mediated photodynamic therapy. Tumors transplanted on the thigh of female WAG/Rij rats were transdermally illuminated with red light (633 nm) after systemic ALA administration (200 mg/kg). The effectiveness of each treatment scheme was determined from the tumor volume doubling time. A single illumination (100 J/cm2 at 100 mW/cm2, 2.5 h after ALA administration) yielded a doubling time of 6.6+/-1.2 days. This was significantly different from the untreated control (doubling time, 1.7+/-0.1 days). The only treatment scheme that yielded a significant improvement compared to all other schemes studied was illumination at both 1 and 2.5 h after ALA administration (both 100 J/cm2 at 100 mW/cm2) and resulted in a tumor volume doubling time of 18.9+/-2.9 days. A possible mechanism to explain this phenomenon is that the protoporphyrin IX formed after administration of ALA is photodegraded by the first illumination. In the 75-min interval, new porphyrin is formed enhancing the effect of the second illumination.
Asunto(s)
Ácido Aminolevulínico/administración & dosificación , Neoplasias Experimentales/tratamiento farmacológico , Fotoquimioterapia/métodos , Animales , Femenino , Luz , Neoplasias Experimentales/patología , Ratas , Factores de TiempoRESUMEN
Monitoring of relevant parameters during photodynamic therapy (PDT) and correlating these with treatment response is necessary to guarantee optimal and reproducible treatment outcome. In this paper we study the correlation between changes in the local tissue optical properties (absorption and scattering coefficients) during ALA-PDT and changes in PpIX fluorescence. The optical properties are measured extremely superficially by employing a single fiber for the delivery and collection of white light to and from the tissue. The measured reflectance spectrum is modeled in terms of four relevant parameters: blood saturation, relative blood volume fraction, scattering intensity and wavelength dependence of the scattering. All these parameters, except the relative blood volume fraction, are shown to correlate with the rate of photobleaching of PpIX, which in turn has previously been shown to correlate with the response of tissues to PDT. These results yield valuable insight in the behavior of these parameters during PDT and their suitability to predict PDT-response for other photosensitizers for which monitoring through photobleaching is not possible.
Asunto(s)
Ácido Aminolevulínico/farmacología , Monitoreo de Drogas/métodos , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/farmacología , Ácido Aminolevulínico/metabolismo , Animales , Ratones , Fármacos Fotosensibilizantes/metabolismo , Espectrometría de FluorescenciaRESUMEN
BACKGROUND AND OBJECTIVE: Fluorescence measurements in the skin are very much affected by absorption and scattering but existing methods to correct for this are not applicable to superficial skin measurements. STUDY DESIGN/MATERIALS AND METHODS: The first use of multiple-diameter single fiber reflectance (MDSFR) and single fiber fluorescence (SFF) spectroscopy in human skin was investigated. MDSFR spectroscopy allows a quantification of the full optical properties in superficial skin (µa, µs' and γ), which can next be used to retrieve the corrected - intrinsic - fluorescence of a fluorophore Qµa,x(f). Our goal was to investigate the importance of such correction for individual patients. We studied this in 22 patients undergoing photodynamic therapy (PDT) for actinic keratosis. RESULTS: The magnitude of correction of fluorescence was around 4 (for both autofluorescence and protoporphyrin IX). Moreover, it was variable between patients, but also within patients over the course of fractionated aminolevulinic acid PDT (range 2.7-7.5). Patients also varied in the amount of protoporphyrin IX synthesis, photobleaching percentages and resynthesis (>100× difference between the lowest and highest PpIX synthesis). The autofluorescence was lower in actinic keratosis than contralateral normal skin (0.0032 versus 0.0052; P<0.0005). CONCLUSIONS: Our results clearly demonstrate the importance of correcting the measured fluorescence for optical properties, because these vary considerably between individual patients and also during PDT. Protoporphyrin IX synthesis and photobleaching kinetics allow monitoring clinical PDT which facilitates individual-based PDT dosing and improvement of clinical treatment protocols. Furthermore, the skin autofluorescence can be relevant for diagnostic use in the skin, but it may also be interesting because of its association with several internal diseases.
Asunto(s)
Queratosis Actínica/patología , Fenómenos Ópticos , Piel , Anciano , Femenino , Tecnología de Fibra Óptica , Fluorescencia , Humanos , Queratosis Actínica/tratamiento farmacológico , Masculino , Imagen Óptica/métodos , Fotoblanqueo , Fotoquimioterapia , Protoporfirinas/biosíntesis , Espectrometría de Fluorescencia/instrumentación , Espectrometría de Fluorescencia/métodos , Análisis EspectralRESUMEN
The success reported for the treatment of superficial skin carcinomas by photodynamic therapy with topical application of the photosensitizer precursor 5-aminolevulinic acid has therapeutic implications for the treatment of other skin disorders. This paper describes the accumulation of the photosensitizing agent protoporphyrin IX in areas of plaque psoriasis by monitoring of the fluorescence emission induced by low-intensity laser excitation at 488 nm. We present results from 15 patients with a total of 42 plaques and show that the characteristic fluorescence emission of protoporphyrin IX increases in intensity within the 6-h period following application of 5-ami-nolevulinic acid, suggesting that there is a potential for superficial photodynamic therapy. The rate of increase and maximum intensity of fluorescence emission was not directly related to the applied quantity of the precursor. The variability of the fluorescence intensity was as great between plaques at different sites on the same patient as between different patients. Also, the effect of plaque occlusion following application appeared insignificant. Although there was only limited enhancement of emission from areas of skin surrounding the plaque, a significant buildup of sensitizer was detected after several days in some areas of psoriasis that received no application.
Asunto(s)
Ácido Aminolevulínico/farmacología , Fotoquimioterapia , Protoporfirinas/farmacocinética , Psoriasis/metabolismo , Psoriasis/terapia , Administración Tópica , Ácido Aminolevulínico/administración & dosificación , Relación Dosis-Respuesta a Droga , Humanos , Fármacos Fotosensibilizantes/farmacocinética , Psoriasis/patología , Pirimidinonas/uso terapéutico , Valores de ReferenciaRESUMEN
OBJECTIVE: To determine the usefulness or otherwise of the awake electroencephalogram (EEG) in the diagnosis of Alzheimer's disease (AD). DESIGN: Prospective collection of one or more awake EEGs in patients diagnosed as having AD or mixed AD and multi-infarct dementia according to current systematic criteria with analysis of those cases confirmed by postmortem examination. Systematized blind interpretation of EEGs. SETTING: Tertiary care practice with both ambulatory and hospitalized patients, ie, neurological department in general hospital and psychogeriatric unit in psychiatric hospital. PATIENTS: A series of 86 subjects with AD and 17 with mixed AD and multi-infarct dementia being those members of a consecutive series on whom postmortem information was available. Awake EEGs in 56 age- and sex-matched control subjects. RESULTS: Seventy-five patients with AD (87.2%) and 13 of the mixed group (76.5%) had abnormal EEGs on first testing, giving a sensitivity of 87.2% for uncomplicated AD. Ultimately, 79 (92%) of 86 patients with AD had abnormal EEGs. Twenty (35%) of 56 EEGs for matching control subjects were abnormal. Moderately abnormal or severely abnormal EEGs were found in 10 (50%) of 20 of the patients with AD of less than 4 year's duration compared with two (4.1%) of 49 of the control subjects, giving a specificity of 95.9% for EEGs with this degree of abnormality. The normal EEG had a negative predictive value of 0.825 with respect to the diagnosis of AD in these populations. CONCLUSIONS: Widespread availability, low cost, and high sensitivity support the use of the awake EEG in the diagnosis of AD.
Asunto(s)
Enfermedad de Alzheimer/diagnóstico , Encéfalo/fisiopatología , Electroencefalografía , Anciano , Enfermedad de Alzheimer/fisiopatología , Demencia por Múltiples Infartos/diagnóstico , Demencia por Múltiples Infartos/fisiopatología , Electroencefalografía/métodos , Femenino , Humanos , MasculinoRESUMEN
Testosterone production by fetal (20.5 days) and neonatal (1-day-old) rat testes was measured to study the possible direct effect of gonadotrophin-releasing hormone (GnRH) on steroidogenesis in early development. Single gonads were incubated in the presence and absence of GnRH (10(-10) to 10(-6) M) or agonistic analogues (10(-11) to 10(-7) M). For comparison, some testes were incubated with ovine luteinizing hormone (0.001-0.01 microgram oLH1 NIH-LH-S20/ml of medium TC199. No clear evidence of stimulation by an agonist (10(-7) M) was seen with fetal testes, but the lowest concentration (10(-11) M) gave results suggestive of an inhibitory action. Similar experiments with neonatal testes showed stimulation. With the highest concentration of GnRH or agonist the amounts of testosterone produced were about 2-3-fold greater than from control testes. Greater quantities of testosterone were found with testes exposed to LH. Hourly sampling in one experiment showed that significant stimulation of testosterone secretion had occurred within the first hour with GnRH (10(-6) M). It was concluded that fetal-neonatal rat Leydig cells are responsive to GnRH.
Asunto(s)
Animales Recién Nacidos/metabolismo , Feto/metabolismo , Hormonas Liberadoras de Hormona Hipofisaria/farmacología , Testículo/metabolismo , Testosterona/metabolismo , Animales , Relación Dosis-Respuesta a Droga , Femenino , Hormona Liberadora de Gonadotropina/análogos & derivados , Hormona Liberadora de Gonadotropina/farmacología , Técnicas In Vitro , Masculino , Embarazo , Ratas , Ratas Endogámicas , Receptores de Superficie Celular/análisis , Receptores LHRH , Testículo/efectos de los fármacosRESUMEN
Tobravirus isolate I6 is an anomalous strain of tobacco rattle virus (TRV), which has biological properties typical of TRV, but which is serologically related to pea early-browning virus (PEBV). Its RNA-2 species is a natural recombinant molecule which contains internal sequences, including the particle protein gene, resembling those of PEBV, but with some TRV-like sequences at each end. Sequencing of RNA-2 of isolate I6 showed that, at the 3' end, it is almost identical to RNA-2 of PEBV strain SP5, and TRV-like sequences are limited to the 25 residues that are common to both viruses. However, unlike PEBV RNA-2, I6 RNA-2 can be replicated by TRV RNA-1-coded enzymes. Thus, specific recognition of RNA-2 by TRV replicase seems not to involve sequences at the 3' end. About 275 residues at the 5' end of I6 RNA-2 are similar to those in RNA-2 of TRV strain TCM, and are jointed to the PEBV-SP5-like subgenomic promoter and coding sequences by about 100 residues of uncertain origin. These results support the idea that I6 RNA-2 originated by recombination between TRV and PEBV RNA-2 molecules, although the exact position of the junction and therefore the mechanism involved are unclear.
Asunto(s)
Virus de Plantas/genética , Virus ARN/genética , ARN Viral/genética , Recombinación Genética/genética , Secuencia de Bases , Datos de Secuencia Molecular , Análisis de Secuencia de ARN , Homología de Secuencia de Ácido NucleicoRESUMEN
An assay involving reverse transcription followed by polymerase chain reaction specifically detected tobacco rattle virus RNA in extracts of infected plants. It detected a wide range of serological variants and typical non-particle producing NM-type isolates. The sensitivity of the method was sufficient to detect TRV RNA in 10 ng total nucleic acid from an infected plant, or in a relatively crude nucleic acid preparation from 60 micrograms infected leaf tissue.