Randomized phase 2 dose comparison LITESPARK-013 study of belzutifan in patients with advanced clear cell renal cell carcinoma.

BACKGROUND: Belzutifan is a first-in-class HIF-2α inhibitor approved at a dose of 120 mg once daily for certain adults with VHL disease and adults with advanced renal cell carcinoma (RCC) following therapy with a programmed death receptor (or ligand)-1 (PD-[L]1) inhibitor and a vascular endothelial growth factor tyrosine kinase inhibitor. However, whether belzutifan dose could be optimized is unclear. PATIENTS AND METHODS: The phase 2 LITESPARK-013 study (NCT04489771) enrolled patients with advanced clear cell RCC whose disease progressed after 1-3 prior systemic therapies, including an anti-PD-(L)1 regimen. Patients were randomly assigned 1:1 to receive belzutifan 120 mg or 200 mg once daily. The primary endpoint was objective response rate (ORR) per RECIST v1.1. Secondary endpoints included duration of response (DOR), progression-free survival (PFS), overall survival (OS), and safety. RESULTS: Overall, 154 patients were enrolled (120 mg: n = 76; 200 mg: n = 78). Median follow-up was 20.1 months (range 14.8-28.4). ORR was 23.7% vs 23.1% for the 120 mg and 200 mg groups, respectively (P = 0.5312; -0.5% [95% CI, -14.0 to 12.9]. Median DOR was not reached for the 120 mg arm and was 16.1 months (2.1+ to 23.5+) for the 200 mg arm. No between-group differences were observed for PFS (HR 0.94 [95% CI 0.63-1.40]) or OS (medians not reached; HR 1.11 [95% CI, 0.65-1.90]). Grade 3 or 4 treatment-related adverse events were observed in 35 patients (46.1%) in the 120 mg group and 36 patients (46.2%) in the 200 mg group. CONCLUSION: The efficacy of belzutifan was similar between the 120-mg dose and the 200-mg dose for previously treated clear cell RCC. Safety at both doses was consistent with the known safety profile of belzutifan. These results further support 120 mg once daily as the preferred dose for belzutifan.

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.

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.

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.

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.

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.

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.

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.

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.

Golgi-Colonnier method: correlation of the degree of chromium reduction and pH change with quality of staining.

We examined the role of chromium reduction in the Golgi-Colonnier method, correlating the quality of neuronal impregnation with the levels of hexavalent (CrVI) and trivalent (CrIII) chromium in the tissue and in the chromation fluid (CF). The concentrations of both chromium species were assessed by measuring spectrophotometrically the CrVI before and after oxidizing the sample and by calculating the ratio of CrVI to total chromium (chromium ratio, CrR). The CrR was almost identical in the tissue and the CF, decreasing exponentially during chromation due to a progressive consumption of CrVI to form CrIII. Satisfactory cell impregnation was obtained only when the CrR was 0.45-0.7, regardless of other factors. The CrR values could be accurately predicted by the pH increase of the CF; this increase has proven to be a most reliable criterion to decide the endpoint of the chromation process. The dependence of cell staining on the [CrIII], together with the well-known ability of this species to bridge proteins, suggests that the key event for cell impregnation is the cross-linking of neuronal proteins by CrIII polymers.

Pilocarpine-induced changes in the saccharide composition of the tectorial membrane and interdental cells of the organ of Corti: a study with gold-labeled lectins.

The glycoconjugates in the cytoplasm of inner ear interdental cells and those constituting the limbal tectorial membrane were identified by a post-embedding cytochemical method using low-temperature embedding in Lowicryl K4M and labeling with biotinylated lectins, goat anti-biotin antibody, rabbit anti-goat antibody, and gold-labeled protein A in control animals, and after the systemic injection of pilocarpine. The lectins used were ConA, PHA-E, PSA, RCA, SBA, Succ-WGA, UEA, and WGA. In control animals, a semiquantitive analysis of gold particles showed that Succ-WGA produced the strongest labeling on the tectorial membrane, followed by SBA, ConA, WGA, RCA, PHA-E, and PSA. The lowest values were obtained with UEA. The cytoplasm of the interdental cells was also labeled with all the lectins, but the number of particles/microns2 was lower than on the tectorial membrane. The concentration of gold particles on the limbal tectorial membrane in pilocarpine-treated animals was higher than in control animals for some lectins (RCA, PSA, UEA) but lower for others (WGA, SBA, PHA-E, Succ-WGA). The changes in the labeling pattern of the cytoplasm of the interdental cells paralleled those in the tectorial membrane. These results demonstrate that the saccharide composition of the limbal tectorial membrane can be modified by systemic injection of pilocarpine. This action may take place through a change in either the secretion rate or the amount of some glycoconjugates by the interdental cells.

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.

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.

The effect of hypothyroidism on the development of the glycogen content of organ of Corti's hair cells.

The density of glycogen particles in organ of Corti's sensory cells was measured to determine the effect of congenital hypothyroidism upon the normal development of this energy source. This density in both normal and hypothyroid inner hair cells remains in low values from birth to adulthood. On the other hand, that of normal outer hair cells undergoes a great increase between the 10th and the 20th postnatal days, coinciding with the maturation of both the efferent innervation of these cells and the tuning properties of the auditory receptor. The glycogen stores of the hypothyroid outer hair cells do not show any significant increase from birth to adulthood. This latter fact suggests that the congenital hypothyroidism restrains the development of an important energy source of outer hair cells, most surely disturbing the physiological processes relying on glycogen metabolism.

Lectin staining of saccharides in the normal and hypothyroid developing organ of Corti.

Lectin staining has been used to detect mono- and oligosaccharides in normal and hypothyroid developing organs of Corti in the rat. Eight developmental stages were studied (1, 5, 8, 10, 15, 20, 50 and 60 days after birth). Congenital hypothyroidism was induced by oral administration of propylthyouracil to pregnant rats. Labelling of the tectorial membrane with 3 lectins, Ulex europaeus agglutinin-I (UEA-I), Lens culinaris agglutinin (LCA) and Ricinus communis agglutinin-I (RCA-I) showed no significant differences between normal and hypothyroid animals. Staining with peanut agglutinin (PNA) showed that the hypothyroid adult tectorial membrane (but not the normal one) possesses the disaccharide galactose + N-acetyl galactosamine. Phaseolus vulgaris agglutinin-L (PHA-L) labels the whole tectorial membrane in both groups of animals, but the staining is more intense in the hypothyroid one for a narrow band of oligosaccharide located just between the tectorial membrane and the underlying organ of Kölliker. Both soybean agglutinin (SBA) and succinylated wheat germ agglutinin (WGA) stain the tectorial membrane as well as the cytoplasm of the cells constituting the inner portion of the organ of Kölliker; this latter feature disappears in the normal animals about the 8th postnatal day, but it is abnormally preserved until the 60th postnatal day in the hypothyroid ones. In the adult hypothyroid animals, 3 of the lectins (LCA, PHA-L and WGA) stain extracellular conglomerates located under the synaptic pole of the outer hair cells.

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.

Regional specialization of the cell coat in the hair cells of the organ of Corti.

The anionic sulfated groups of the cell coat glycoconjugates were studied in sensory and supporting cells of the organ of Corti with the colloidal iron hydroxide technique of Mowry, modified by Seno et al. [(1985) Histochemistry 82, 307-312]. This technique specifically stains the apical (endolymphatic) surface of both inner and outer hair cells. As this is the area at which the influx of potassium into the sensory cells takes place, the accumulation of negative charges in this location may be a mechanism to concentrate cations (mainly potassium) close to this portion of the hair cell membrane.