Development of a 3D printing process of bolus using BolusCM material for radiotherapy with electrons.

This work presents the optimized parameters of 3D printing for print bolus using BolusCM material. Printing parameters were selected of the homogeneity and absence of air gaps. The dosimetric features of printed bolus were measured with a plane-parallel ionization chamber and EBT3 radiochromic film. Measured features were compared with those estimated with Monte Carlo methods. BolusCM shows good characteristics to be used as bolus material in radiotherapy with electrons, where the printing process allows personalizing the bolus in function of patient characteristics. The material low-cost, the 3D printing and the dosimetric features are few of the advantages of using BolusCM material in radiotherapy with electrons in skin cancer treatment.

Bolus 3D printing for radiotherapy with conventional PLA, ABS and TPU filaments: Theoretical-experimental study.

A theoretical-experimental study of the interaction of electron beams with 3 filaments conventionally used for 3D printing is presented in this paper. Pieces of polylactic acid (PLA), acrylonitrile butadiene styrene (ABS) and thermoplastic polyurethane (TPU) are studied using Monte Carlo simulation with Geant4 and experimental measurements with plane-parallel ionization chambers and radiochromic films. Using different printing parameters and computed tomography, the presence of air gaps and the uniformity in the bolus density made with the different materials are evaluated. The main parameters in the Percentage Depth Dose (PDDs) are determined, the manufacturing process is standardized and the printing profiles are generated for each of the materials in order to obtain uniform attenuation characteristics in the pieces and improve adaptation to irregular anatomical areas.

Characterization of a novel material to be used as bolus in radiotherapy with electrons.

Features of new material to be used as bolus in external radiotherapy were determined and their performance were evaluated. The characterization was carried out using Monte Carlo methods with the Geant4 code where the Percentage Depth Dose (PDD) due to electrons was estimated. In the Monte Carlo model the linear accelerator head was included. Calculated results were experimentally validated with measurements made for 6, 9, 12 and 16 MeV electron beams. The key characteristics of the implemented material were identified, guaranteeing a low cost bolus, easy to be customized and to be used in clinical applications. In comparison with commercial materials the new materials are superior from the cost to the effectiveness of their use in clinical treatments.

Angiographic and Clinical Profile of Patients With COVID-19 Referred for Coronary Angiography During SARS-CoV-2 Outbreak: Results From a Collaborative, European, Multicenter Registry.

Data regarding angiographic characteristics, clinical profile, and inhospital outcomes of patients with coronavirus disease 2019 (COVID-19) referred for coronary angiography (CAG) are scarce. This is an observational study analyzing confirmed patients with COVID-19 referred for CAG from 10 European centers. We included 57 patients (mean age: 66 ± 15 years, 82% male) , of whom 18% had previous myocardial infarction (MI) and 29% had renal insufficiency and chronic pulmonary disease. ST-segment elevation myocardial infarction (STEMI) was the most frequent indication for CAG (58%). Coronavirus disease 2019 was confirmed after CAG in 86% and classified as mild in 49%, with 21% fully asymptomatic. A culprit lesion was identified in 79% and high thrombus burden in 42%; 7% had stent thrombosis. At 40 days follow-up, 16 (28%) patients experienced a major adverse cardiovascular event (MACE): 12 deaths (92% noncardiac), 1 MI, 2 stent thrombosis, and 1 stroke. In an European multicenter registry, patients with confirmed COVID-19 infection referred for CAG during the first wave of the severe acute respiratory syndrome coronavirus 2 pandemic presented mostly with STEMI and were predominantly males with comorbidities. Severity of COVID-19 was in general noncritical and 21% were asymptomatic at the time of CAG. Culprit coronary lesions with high thrombus burden were frequently identified, with a rate of stent thrombosis of 7%. The incidence of MACE at 40 days was high (28%), mostly due to noncardiac death.

Papel de la linfadenectomía paraaórtica inframesentérica durante la histerectomía radical en pacientes con cáncer cervical estadio IB1 en el Instituto Nacional de Cancerología Bogotá, Colombia / Role of inframesenteric para-aortic lymphadenectomy during radical hysterectomy in patients with IB1 cervical cancer in Instituto Nacional de Cancerología Bogota, Colombia

INTRODUCCIÓN: El cáncer cervical es una patología común en países en vías de desarrollo. La histerectomía radical es el estándar de manejo en estadios tempranos sin deseo de fertilidad. La linfadenectomía paraaórtica como parte del tratamiento quirúrgico es controversial. El objetivo de este estudio es determinar la frecuencia de compromiso ganglionar paraaórtico en una serie retrospectiva de pacientes con carcinoma cervical estadio IB1 (clasificación FIGO 2009) llevadas a histerectomía radical mas linfadenectomía pélvica y paraaórtica en el Instituto Nacional de Cancerología durante el periodo de enero 1 de 2009 a marzo 31 de 2017. MÉTODOS: Estudio descriptivo, retrospectivo. Se describieron variables clínicas, operatorias e histopatológicas. Se determinó la frecuencia de compromiso ganglionar a nivel paraaórtico o pélvico, y concurrente. Se realizó análisis univariado en el software estadístico R Project versión 3.6.0. RESULTADOS: Se incluyeron 88 casos. El promedio de edad fue 44,24 ± 9,99 años. La mediana del número de ganglios pélvicos y paraaórticos resecados fue de 23 (6-68) y 4 (1-25), respectivamente. En el 12,5% de las pacientes se observó compromiso tumoral ganglionar pélvico. No se detectó compromiso metastásico de ganglios paraórticos en ningún caso. Dos pacientes presentaron recaída ganglionar paraaórtica durante el seguimiento, recibiendo tratamiento con quimioterapia y quimiorradioterapia de campo extendido, respectivamente. CONCLUSIÓN: En este estudio no se detectó compromiso paraaórtico en pacientes con cáncer cervical IB1 sometidas a histerectomía radical. Este resultado se debe considerar al ofrecer linfadenectomía paraaórtica en pacientes con ganglios pélvicos aparentemente normales en el acto operatorio y/o en los estudios de imágenes prequirúrgicas.

INTRODUCTION: Cervical cancer is a common pathology in developing countries. Radical hysterectomy is the standard of management in early stages without desire for fertility. Paraaortic lymphadenectomy as part of surgical treatment is controversial. The objective of this study is to determine the frequency of paraaortic lymph node involvement in a retrospective series of patients with stage IB1 cervical carcinoma (FIGO 2009 classification) underwent to radical hysterectomy plus pelvic and paraaortic lymphadenectomy at the Instituto Nacional de Cancerologia during the period of January 1 2009 to March 31 2017. METHODS: Descriptive, retrospective study. Clinical, operative, and histopathological variables were described. The frequency of paraaortic, pelvic, concurrent lymph node involvement and adjuvant treatment was determined. A univariate analysis of the variables was performed in the R project statistical software version 3.6.0. RESULTS: 88 cases were included. The mean age was 44,24 ± 9,99 years. The median number of resected pelvic and para-aortic nodes was 23 (6-68) and 4 (1-25), respectively. In 12,5 % of the patients, involvement of the pelvic lymph nodes was present. No patient had paraaortic lymph node involvement. Two patients presented para-aortic lymph node relapse during follow-up, receiving treatment with chemotherapy and extended field chemoradiotherapy, respectively. CONCLUSION: In this study, the frequency of paraaortic involvement in patients with cervical cancer IB1 was 0%. This result should be considered when offering paraaortic lymphadenectomy in patients with apparently normal pelvic nodes in presurgical imaging studies and during the procedure.

Safety and clinical activity of the Notch inhibitor, crenigacestat (LY3039478), in an open-label phase I trial expansion cohort of advanced or metastatic adenoid cystic carcinoma.

Background Deregulated Notch signaling is implicated in multiple cancers. The phase I trial (I6F-MC-JJCA) investigated the safety and anti-tumor activity of crenigacestat (LY3039478), a selective oral Notch inhibitor, in an expansion cohort of patients with adenoid cystic carcinoma (ACC) who received the dose-escalation-recommended phase 2 dose (RP2D), established previously (Massard C, et al., Annals Oncol 2018, 29:1911-17). Methods Patients with advanced or metastatic cancer, measurable disease, ECOG-PS ≤1, and baseline tumor tissue were enrolled. Primary objectives were to identify a safe RP2D, confirm this dose in expansion cohorts, and document anti-tumor activity. Secondary objectives included safety and progression-free survival (PFS). The ACC expansion cohort received the RP2D regimen of 50 mg crenigacestat thrice per week in a 28-day cycle until disease progression or other discontinuation criteria were met. Results Twenty-two patients with ACC were enrolled in the expansion cohort (median age of 60 years). Median treatment duration was 3 cycles with 6 patients remaining on treatment. There were no objective responses; 1 (5%) patient had an unconfirmed partial response. Disease control rate was 73% and 4 patients had stable disease ≥6 months. Median PFS was 5.3 months (95%CI: 2.4-NE)) for the 22 patients; and 7.7 months (95%CI: 4.0-NR) and 2.4 months (95%CI: 1.1-NE) in the subgroup of patients in second-line (n = 7) or ≥ third-line (n = 9), respectively. Frequent treatment-related-adverse events (all grades) included diarrhea, fatigue, vomiting, decreased appetite, dry mouth, and dry skin. There were no new safety signals. Conclusion The crenigacestat RP2D regimen induced manageable toxicity and limited clinical activity, without confirmed responses, in heavily pretreated patients with ACC.

Prospective study of the 532 nm laser (KTP) versus diode laser 980 nm in the resection of hyperplastic lesions of the oral cavity.

BACKGROUND: The aim of this study is to evaluate the resection of hyperplastic lesions on the buccal mucosa comparing the 532nm laser (KTP), versus diode 980nm laser, considering pain, scarring, inflammation and drug consumption that occurred postoperatively with each lasers. MATERIAL AND METHODS: A prospective study of consecutive series of 20 patients in two groups that presents hyperplastic lesions on the buccal mucosa. The choice of the KTP laser or diode 980nm laser for the surgery was made randomly. The power used was 1.5W in both groups in a continuous wave mode with a 320 µm optical fiber. Parameters of pain, scarring, inflammation and consumption of drugs were recorded by a Numerical Rating Scale and evaluated postoperatively. These recordings were made the day of the surgery, 24 hours after, 14 and 28 days after. RESULTS: Pain and inflammation was light - moderate. The consumption of paracetamol was somewhat higher in the diode 980nm laser versus the KTP laser after 24 hours, although data was not statistically significant; significant differences were found after 28 days in regards to pain (p = 0.023) and inflammation (p = 0.023), but always in the absence parameter so we find no pain in both lasers. Scarring in the two types of laser showed no differences along the visits, with not detected scar retractable. CONCLUSIONS: Although there is a slight histological difference regarding the KTP laser in the oral soft tissues for clinical use, both wavelengths are very suitable for excision of oral fibroma.

Assessment of the effectiveness of attenuation of Pb aprons by using TLD dosimetry and Monte Carlo calculations.

We developed an experimental set-up by using a continuous emission X-ray (Pantak DXT-3000) and three types of Pb aprons, with thicknesses of 0.25, 0.5, and 0.75mm, coated with Mylar fiber on their surface. Aprons were placed at a distance of 2.5m from the focus. Aluminum filtration was performed at the beam output to reproduce the qualities of narrow beams, N40 (Eeffective =33keV), N80 (Eeffective =65keV), and N100 (Eeffective =83keV), according to the ISO standard 4037 (1-3). Each apron was fixed with 10 thermoluminescent dosimeters (TLDs) over its surface, five dosimeters before and five dosimeters after irradiation with X-rays. Dosimeter readings were noted, and the attenuation coefficients for each effective energy were calculated. To confirm the method of effective energy of ISO-4037 and evaluate the effectiveness of aprons according to the energy range required for different medical practices, a Monte Carlo simulation using GEANT4 code was performed. Thus, the fluence and the absorbed dose in each of the dosimeters were determined, and then the coefficients of linear attenuation were calculated and compared with the experimental data and with those reported by the National Institute of Standards and Technology. Results were consistent between theoretical calculations and experimental measures. This work will serve to make assessments for other personalized radiation protectors made of Pb.

Transcatheter closure of paravalvular leaks: state of the art.

Paravalvular leak (PVL) is a serious complication after surgical valve replacement or after transcatheter aortic valve replacement. Approximately 1-5% of PVLs can lead to serious clinical consequences, including congestive heart failure and/or haemolytic anaemia. For years, surgical re-intervention has been considered the treatment of choice for symptomatic patients with PVLs. However, surgical re-intervention is associated with a high risk of morbidity and mortality. Transcatheter PVL (TPVL) closure is a less invasive alternative to surgical re-intervention. The safety and feasibility of TPVL closure has been confirmed in several registries and a meta-analysis.In this review, we discuss the clinical implications and diagnosis of PVLs, technical considerations for TPVL, execution of the procedure and assessment of the results.

¿Qué utilidad tiene la ecografía para el pediatra de Atención Primaria? / Are ultrasound scans useful for the Primary Care paediatrician?

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In vivo safety, biodistribution and antitumor effects of uPAR retargeted oncolytic measles virus in syngeneic cancer models.

The urokinase receptor (uPAR) is a clinically relevant target for novel biological therapies. We have previously rescued oncolytic measles viruses fully retargeted against human (MV-h-uPA) or murine (MV-m-uPA) uPAR. Here, we investigated the in vivo effects of systemic administration of MV-m-uPA in immunocompetent cancer models. MV-m-uPA induced in vitro cytotoxicity and replicated in a receptor-dependent manner in murine mammary (4T1) and colon (MC-38 and CT-26) cancer cells. Intravenous administration of MV-m-uPA to 4T1 tumor-bearing mice was not associated with significant clinical or laboratory toxicity. Higher MV-N RNA copy numbers were detected in primary tumors, and viable viral particles were recovered from tumor-bearing tissues only. Non-tumor-bearing organs did not show histological signs of viral-induced toxicity. Serum anti-MV antibodies were detected at day 14 of treatment. Immunohistochemistry and immunofluorescence studies confirmed successful tumor targeting and demonstrated enhanced MV-m-uPA-induced tumor cell apoptosis in treated compared with control mice. Significant antitumor effects and prolonged survival were observed after systemic administration of MV-m-uPA in colon (CT-26) and mammary (4T1) cancer models. The above results show safety and feasibility of uPAR targeting by an oncolytic virus, and confirm significant antitumor effects in highly aggressive syngeneic immunocompetent cancer models.

Mesenchymal stromal-cell transplants induce oligodendrocyte progenitor migration and remyelination in a chronic demyelination model.

Demyelinating disorders such as leukodystrophies and multiple sclerosis are neurodegenerative diseases characterized by the progressive loss of myelin that may lead toward a chronic demyelination of the brain's white matter, impairing normal axonal conduction velocity and ultimately causing neurodegeneration. Current treatments modifying the pathological mechanisms are capable of ameliorating the disease; however, frequently, these therapies are not sufficient to repress the progressive demyelination into a chronic condition and permanent loss of function. To this end, we analyzed the effect that bone marrow-derived mesenchymal stromal cell (BM-MSC) grafts exert in a chronically demyelinated mouse brain. As a result, oligodendrocyte progenitors were recruited surrounding the graft due to the expression of various trophic signals by the grafted MSCs. Although there was no significant reaction in the non-grafted side, in the grafted regions oligodendrocyte progenitors were detected. These progenitors were derived from the nearby tissue as well as from the neurogenic niches, including the subependymal zone and dentate gyrus. Once near the graft site, the cells matured to myelinating oligodendrocytes. Finally, electrophysiological studies demonstrated that axonal conduction velocity was significantly increased in the grafted side of the fimbria. In conclusion, we demonstrate here that in chronic demyelinated white matter, BM-MSC transplantation activates oligodendrocyte progenitors and induces remyelination in the tissue surrounding the stem cell graft.

The anticancer effects of chaetocin are independent of programmed cell death and hypoxia, and are associated with inhibition of endothelial cell proliferation.

BACKGROUND: We previously reported that chaetocin has potent and selective anti-myeloma activity attributable to reactive oxygen species (ROS) induction imposed by inhibition of the redox enzyme thioredoxin reductase; we now detail its effects in solid tumours. METHODS: Cellular assays, transcriptional profiling and the NCI60 screen were used to assess the effects of chaetocin in solid tumour and endothelial cells. RESULTS: NCI-60 screening demonstrated chaetocin to even more potently inhibit proliferation in solid tumour than in haematological cell lines; transcriptional profiling revealed a signature consistent with induction of inflammatory response and cell death pathways. Chaetocin induced ROS, oxidative damage to cellular proteins and apoptosis, with 2-10 nM IC(50)s (24 h exposures) in all tested solid tumour cell lines. The pan-caspase inhibitor zVAD-fmk did not block chaetocin-induced cell death despite inhibiting mitochondrial membrane depolarisation and apoptosis. Further, Molt-4 rho(0) cells lacking metabolically functional mitochondria were readily killed by chaetocin; in addition chaetocin-induced cytotoxicity was unaffected by autophagy inhibitors or hypoxia and consequent HIF-1α upregulation. Moreover, chaetocin inhibited SKOV3 ovarian cancer xenografts producing less vascular tumours, and inhibited human umbilical vein endothelial cell proliferation. CONCLUSION: Chaetocin has intriguing and wide-ranging in vitro and in vivo anticancer effects, and is an attractive candidate for further preclinical and clinical development.

Actinomicosis abdominal y pélvica: reto diagnóstico y quirúrgico para el cirujano general / Abdominal and pelvis actinomycosis: a diagnostic and surgical challenge for the general surgeon

La actinomicosis es una enfermedad infecciosa bacteriana de presentación infrecuente y de muy difícil diagnóstico preoperatorio. Es causada por Actinomyces israelii, una bacteria Gram positiva y anaerobia estricta que, comúnmente, se encuentra en la orofaringe, en el sistema gastrointestinal y en la vagina. Las infecciones más frecuentes por Actinomyces spp. se presentan clínicamente en el área cérvico-facial, en el tórax y en la cavidad abdomino-pélvica. Esta última se ha asociado al uso crónico (mayor de 5 años) del dispositivo intrauterino.Se presenta el caso de una paciente joven, de 26 años de edad, quien consultó inicialmente al Servicio de Ginecología por dolor pélvico crónico y masa pélvica mal definida de varios meses de evolución. La paciente fue finalmente remitida al Servicio de Cirugía General del hospital departamental de Pitalito, Huila, donde se estableció el diagnóstico de actinomicosis abdomino-pélvica en el posoperatorio. Actualmente, la paciente se encuentra en buen estado general y recibe tratamiento prolongado con penicilina oral.

Abdominal and pelvic actinomycosis is a fairly rare chronic suppurative infectious disease of very infrequent presentation. It is caused by the Actinomyces israellí, a strictly anaerobic gram positive bacteria commonly found in the oropharinx, the gastrointestinal tract and the vagina. The most frequent clinical presentation of the disease involves the neck, the entire facial area, the thorax and the abdomino-pelvic cavity. The latter has been associated with the chronic use (more than five years) of the intrauterine contraceptive device (IUD). The case of a 26-year old female patient is reported. She first presented with a history of several months of chronic pelvic pain and a firm non tender pelvic mass. She was then submitted to the department of general surgery of the State Hospital of Pitalito, Huila, Colombia, where de diagnosis of abdomino-pelvic actynomicosis was established postoperatively. The patient is doing well so far and still receives oral penicillin treatment.

[Antibiotic prescribing patterns for pediatric inpatients with acute respiratory tract infection]. / Uso de antibióticos en niños hospitalizados por infección respiratoria aguda.

BACKGROUND: Children with acute respiratory tract infection (ARTI) represent an important target group for efforts aimed at reducing unnecessary antibiotic use. OBJECTIVE: To present the epidemiological data and evaluate the effect of clinical, laboratory, radiological and microbiological data on the decision to prescribe antibiotics to pediatric patients with ARTI as well as to seek criteria that would justify antibiotic use. PATIENTS AND METHODS: A retrospective review was made of the clinical histories of 147 previously healthy children, consecutively admitted to our hospital with ARTI for 1 year (May 1996-April 1997). Patients were divided in two groups: those not treated with antibiotics (n = 92) and those treated (n = 55). Data from the two groups were compared with a statistical computer program (R-Sigma). RESULTS: Of the 147 patients studied, mean age was 2.5 years (range 0-14 years) and 85 (58%) males. One-hundred-and-five patients (72%) had previously been attended to in the emergency room, and 45 patients (30%) had been treated with antibiotics. Upper respiratory tract infection was diagnosed in 81 patients (54%), bronchitis in 28 (18%), bronchiolitis in 23 (15%) and pneumonia in 15 (10%). Ninety-seven patients (66%) had viral infection and only two (1%) had bacterial infection. Syncytial respiratory virus was isolated in 41 patients (28%) and adenovirus in 30 (20%). In the untreated group, the longer duration of symptoms before admission, lymphocytosis, clinical diagnosis of bronchiolitis and normal thorax X-ray, were statistically significant. In the treated group, fever, leukocytosis, neutrophilia and a diagnosis of pneumonia were statistically significant. Length of stay was longer in this group than in the untreated group. CONCLUSIONS: It is difficult to prescribe antibiotics on the basis of bacteriologic data. Laboratory, analytic and radiological data can be helpful in the rational use of antibiotics.

Uso de antibióticos en niños hospitalizados por infección respiratoria aguda / Antibiotic prescribing patterns in pediatric inpatients with acute respiratory tract infection

Antecedentes: Los niños con infección respiratoria aguda constituyen un grupo permanente de estudio para evitar el tratamiento innecesario con antibióticos. Objetivo: Presentar los datos epidemiológicos y estudiar el efecto que tienen los datos clínicos, analíticos, radiológicos y microbiológicos en la decisión de tratar con antibióticos a niños hospitalizados por infección respiratoria aguda, buscando criterios que justifiquen su uso. Pacientes y métodos Se revisan las historias clínicas de 147 niños ingresados consecutivamente por catarro de vías altas, bronquitis, bronquiolitis y neumonía, durante un año (mayo 1996-abril 1997). Los pacientes se dividieron en 2 grupos: pacientes no tratados con antibióticos (n = 92), y pacientes tratados (n = 55) y se compararon estadísticamente los datos mediante un programa R-Sigma. Resultados En el conjunto de la serie, la edad media fue de 2,5 años con predominio de varones 85 (58 por ciento); habían consultado previamente en urgencias 105 pacientes (72 por ciento) y estaban recibiendo antibióticos 45 pacientes (30 por ciento). Se diagnosticó catarro de vías altas en 81 pacientes (54 por ciento), bronquitis en 28 (18 por ciento), bronquiolitis en 23 (15 por ciento) y neumonía en 15 (10 por ciento). Hubo 97 pacientes (66 por ciento) con infección viral demostrada y 2 (1 por ciento) bacteriana. El virus respiratorio sincitial se aisló en 41 pacientes (28 por ciento) y el adenovirus en 30 (20 por ciento). Entre los pacientes no tratados resultaron estadísticamente significativos la mayor duración de los síntomas antes del ingreso, la linfocitosis, el diagnóstico de bronquiolitis y la radiografía de tórax normal. Entre los pacientes tratados fueron estadísticamente significativas fiebre, leucocitosis, neutrofilia y el diagnóstico de neumonía, siendo así mismo más larga la estancia hospitalaria. Conclusión En nuestro medio, es difícil indicar un tratamiento antibiótico basándose en criterios bacteriológicos; los criterios clínicos, radiológicos y analíticos pueden ayudar en la toma de decisiones (AU)

Specific staining of nonpyramidal cell populations of the cerebral cortex by lectin cytochemistry on semithin sections.

The pattern of lectin labeling in the cerebral cortex of the cat was studied using semithin sections. The labeling produced by some lectins (Concanavalin A, Lens culinaris, Phaseolus vulgaris-L, Phaseolus vulgaris-E, Pisum sativum, wheat germ agglutinin, and succynilated-wheat germ) appeared inside every neuron as small cytoplasmic granules, probably corresponding to cisterns of endoplasmic reticulum and/or the Golgi complex. Lectins with affinity for alpha-mannosyl residues (Pisum sativum, Lens culinaris, and Concanavalin A) stained the cell surface of a subset of cortical neurons. The labeled cells were round or polygonal, medium to large neurons present in layers II-VI, exhibiting the morphological features of nonpyramidal cells. Previous lectin studies of perineuronal nets have shown that these extracellular specializations contain N-acetylgalactosamine and N-acetylglucosamine. Our results show that mannose is also a component of perineuronal nets and that lectins specific for alpha-mannose can be used as tools for the cytochemical detection of a separate class of cortical neurons, which have not yet been fully characterized. In addition, some lectins (Bandeiraea simplicifolia, Concanavalin A, Lens culinaris, Phaseolus vulgaris-L, Phaseolus vulgaris-E, Pisum sativum, and succynilated-wheat germ agglutinin) specifically labeled a population of a type of microglia-related cells known as perivascular cells. The data presented here report for the first time the selective staining of perivascular cells and further support the hypothesis that they are different from typical microglial cells.

Structure of glycogen particles in organ of Corti's outer hair cells in three rodent species.

Organ of Corti's outer hair cells are one of the few cell types in mammals to contain large cytoplasmic glycogen stores, and the only one in the adult auditory receptor. Previous reports on the structure and distribution of glycogen in the adult organ of Corti were mainly based on light microscopy histo- and cytochemical methods, and the scare EM studies on the topic relied on techniques which were not sensitive or specific enough. Furthermore, it has been reported that glycogen particles are not present in outer hair cells of all species. A first goal of the present study was to describe the ultrastructure of glycogen stores in organ of Corti's outer hair cells in Guinea pig, rat, and mouse, using the periodic acid-thiocarbohydrazide-silver proteinate method. In addition, differences in the subcellular and cochleotopic distribution of this substance were analyzed. In the adult organ of Corti only the outer hair cells contain glycogen stores. Present throughout their cytoplasm, these deposits appear either as single beta particles, or as aggregates of these, forming alpha particles. Though most alpha particles are round, some appear long and conspicuously straight in longitudinal sections of those cells near the apex of the cochlea, and they seem to be apposed to some filamentous structure. On the other hand, when the cells are sectioned transversely the larger aggregates of glycogen particles follow a curved course. Since outer hair cells of the apical region of the cochlea contain a bundle of contractile microfilaments, our results suggest that glycogen is associated with the contractile apparatus of these cells. This hypothesis is in good accordance with previous experimental data which suggest that glycogen is used as energy source for the contractile movements of outer hair cells.

Development of vestibular function: biochemical, morphological and electronystagmographical assessment in the rat.

Glutamate decarboxylase and choline acetyltransferase were measured in homogenated ampullar cristae of rats during development from postnatal day 13 to 60 to determine changes in levels of these enzymes during early postnatal development. Afferent and efferent innervation of the hair cells of the developing cristae were studied using electron microscopy. In parallel, groups of rats, postrotatory nystagmus were used to assess the development of semicircular canal function during the same time interval. The level of glutamate decarboxylase was high on postnatal day 15 and did not change notably over the remaining days to day 60. Activity of choline acetyltransferase was nearly absent at day 15, but reached levels seen in mature animals by day 17, and remained almost unchanged thereafter. In contrast, as revealed by electronmicroscopy, afferent and efferent innervation appeared to be mature by day 8. Postrotatory nystagmus presented the adult-like features from day 19 onward. According to these results, a role for glutamate decarboxylase in afferent transmission is suggested by the parallel development of levels of glutamate decarboxylase and afferent innervation of the ampullary cristae. The finding of a similar time course of development of choline acetyltransferase levels and postrotatory nystagmus suggests that a cholinergic efferent innervation is involved in the onset of vestibular-ocular function.

A reliable method for Golgi staining of retina and brain slices.

Although the classical Golgi method is a powerful means for structural analysis of the brain, it is generally considered to be an unpredictable technique making anatomists wary of using it. Often, even when successful staining has occurred, deposits of silver chromate crystals on the surface of the tissue obscure examination. This paper describes a simple procedure for Golgi impregnation of retina and brain slices so that good, even staining is obtained and crystal formation is avoided. The most outstanding feature of the method is the consistency of results. This consistency is due to two factors: (1) the accurate determination of the optimal chromation by measuring the rise of pH in the solutions and (2) the uniform penetration of dichromate and silver nitrate to the specimen by using a freely hanging, sandwiching technique. We suggest that the method described here can be applied to other parts of the nervous system and will be a reliable way to identify and better classify new cell types.