Bruna Biondo

Severe hypoplasia of medullary arcuate nucleus: quantitative analysis in sudden infant death syndrome.

Abstract The human arcuate nucleus (ARCn) is postulated to be homologous to ventral medullary cells involved in chemoreception, and respiratory and blood pressure responses. Abnormalities in central respiratory control may result from dysfunction of this anatomic ventral area. We evaluated the changes of the neuronal population of the medullary ARCn in infants victims of the sudden infant death syndrome (SIDS). In this study we tested the hypothesis that anatomical deficiency of the ARCn is associated with SIDS. The volume and neuronal density of the ARCn were morphometrically quantified with an image analyzer in 36 cases of SIDS and 12 age-matched controls. We found a marked hypoplasia in the SIDS ARCn compared to controls and, particularly, in 11 SIDS cases (30%) in which the ARCn exhibited a severe hypoplasia, being almost totally absent. Three-dimensional reconstructions and morphometric measurements of ARCn confirmed this marked hypoplasia in all the serial sections examined (P = 0.0001) and the reduced neuronal density (P = 0.0025) in relation to control cases. In conclusion these abnormalities observed in the ARCn are consistent with the idea that ARCn dysfunction plays an important role among the causative factors of sudden infant death. The hypoplasia of the ARCn represents the most frequent congenital abnormality in our experience, and can be a plausible morphological substrate for a subset of SIDS.

Brain stem lesions in the sudden infant death syndrome: variability in the hypoplasia of the arcuate nucleus

Abstract. In the present study we investigated quantitatively the incidence of hypoplasia of the arcuate nucleus (ARCn) of the medulla oblongata, reported earlier [Gozal D, Hathout GM, Kirlew KAT (1994) J Appl Physiol 76:207], as well as its distribution in 62 cases of sudden infant death syndrome (SIDS; mean age 14 postnatal weeks, 39 male and 23 female) and 25 controls (mean age 16 postnatal weeks, 14 male and 11 female), using detailed histopathological and morphometric analyses performed on serial sections of medulla oblongata. The SIDS cases were divided into four subtypes: SIDS A (27 cases, 43%) with histologically well-developed ARCn; SIDS B (16 cases, 26%) with severe bilateral hypoplasia along the whole length; SIDS C (11 cases, 18%) with partial bilateral hypoplasia, located mainly in the lateral portions of the caudal two thirds of the nucleus, and SIDS D (8 cases, 13%) with right monolateral hypoplasia of the ARCn. ARCn hypoplasia was detected in 56% of cases (35 cases). Three-dimensional volume reconstruction showed that in the SIDS A victims the mean volume was analogous to controls, whereas in the SIDS group with ARCn hypoplasia, severe or partial, the mean volume was significantly different from controls on both sides of the medulla oblongata (SIDS B group: P=0.003, P=0.002; SIDS C group: P=0.007, P=0.008). The mean ARCn volume in the SIDS D group was statistically significant only on the right side (P=0.005). We also observed reduced neuron density of the ARCn, associated with a decrease in the total number of neurons over the whole length of the nucleus itself. On the basis of the morphometric results of neuronal population in the different portions of the ventrolateral medulla in SIDS cases, we hypothesized that infants without the full complement of neurons and neuropil (ARCn hypoplasia) are at risk for SIDS because they are unable to develop appropriate cardioventilatory control during this crucial developmental period.

Glial and neuronal alterations in the nucleus tractus solitarii of sudden infant death syndrome victims.

The factors underlying the sudden infant death syndrome (SIDS) are still unknown, but in recent years much attention has been focused on the central cardiorespiratory control system. In the present work we analyzed the nucleus tractus solitarii (nTS) of 23 SIDS victims and 17 age-matched control cases. We studied the functional and morphological alterations of neurons and glial cells to evaluate the results of possible hypoxic-ischemic injury that could have led to sudden death. Morphometric and immunohistochemical analyses were performed on medullary sections. In the nTS of SIDS victims we observed modifications of both neuronal and glial cells. Brain injury triggers the activation of both astrocytes and microglia, which respond to neuronal damage by characteristic changes that could explain our observations in the nTS of SIDS victims. In our investigation of the nTS of SIDS victims we found a significant increase of reactive astrocytes density, a significantly higher percentage of necrotic cells, an increase of reactive microglial cells density, a significantly higher expression of substance P and the presence of NMDA receptors immunoreactivity. Our results support the hypothesis that there is injury of the nTS neurons in SIDS victims, even if the causes of this damage are still unknown. This neuronal damage may explain why adequate ventilation is often not maintained during hypoxia. Such histological findings have never been thought sufficient to explain SIDS, but the tissue findings could be an indication of the impairment of several pathophysiological mechanisms which may underlie brainstem dysfunction, affecting cardiorespiratory control.

Delayed neuronal maturation of the medullary arcuate nucleus in sudden infant death syndrome

Recently, quantitative abnormalities in neuronal populations derived from the rhombic lip (inferior olive nucleus of the brain stem and external granular layer of the cerebellum) have been reported in victims of the sudden infant death syndrome (SIDS). In this study we examined the arcuate nucleus (ARCn) of 35 SIDS victims and 25 controls, to determine neuronal abnormalities involving this nucleus in SIDS. Computer-assisted cell evaluation was made on sections stained with hematoxylin and eosin to study the neuronal dimensions (nuclear and cytoplasmic area, nuclear/cytoplasmic ratio), the form factor and the density of reactive astrocytes. There was a significant reduction of the neuronal area (nuclear and cytoplasmic) in SIDS victims compared with controls. The neuronal populations of SIDS victims had a significantly higher form factor, index of immaturity. The SIDS victims were divided into two groups on the basis of ARCn development: 18 SIDS-A cases with a well-developed ARCn and 17 SIDS-B cases with severe bilateral hypoplasia. The results of our research indicate that the developmental defect is characterized by a reduction in size of the ARC neurons and by neuronal depletion. In SIDS the ARCn has the histomorphological features of neuronal immaturity, and there is a marked reduction of all quantitative cell parameters and lower astrocytes density with respect to controls. On the basis of the morphometric results of the arcuate neuronal populations, we hypothesize that infants whose neurons have failed to reach full maturity are at risk for SIDS because they are unable to develop appropriate cardioventilatory control.

Cell kinetics of pleomorphic adenomas of the parotid gland

The aim of the present study is to characterise the cell kinetics of pleomorphic adenoma of the parotid gland by assessing DNA content and proliferating cell nuclear antigen (PCNA) positivity. In 22 parotid adenomas, DNA content was measured by densitometry in histological serial sections stained with Feulgens method and PCNA positivity was determined by immunohistochemistry with the monoclonal antibody PC10. To assess the proliferative activity, DNA index and PCNA index were evaluated. It was possible to distinguish two types of adenoma. In Group I there was a prevalence of diploid cells with a low PCNA index. Group II is represented by adenomas with a large percentage of triploid cells and a PCNA index significantly higher than that of Group I. Our findings suggest that the possibility of recurrence or malignant transformation depends on intrinsic biological properties of each adenoma.

Glomerular morphometry of twenty-three biopsied patients with IgA nephropathy

The aim of the present study was the process of an easy method for quantitative evaluation of the alterations of the mesangial matrix, cellularity and urinary space in IgA glomerulonephritis (IgA-GN) by the image analysis technique. A Vidas (Kontron-Zeiss) image analyzer was employed for the morphometric study of renal biopsies from 23 patients with IgA-GN. The following parameters were assessed: mesangial matrix index, expressed as the ratio between mesangial area and total glomerular area x 100; mesangial cellularity index, considered as the ratio between the total number of nuclei contained in the glomerulus and the overall glomerular area in mm2 x 10(4); urinary space/glomerular area ratio. The morphometric results compared to the respective values observed in normal glomeruli indicate an increase in the overall area of glomeruli with IgA-GN and, conversely, a decrease in the total area occupied by the urinary space (p = 0.0001). It can therefore be concluded that the morphometric determination of the morphologic abnormalities occurring in the renal glomerulus with IgA-GN is an extremely useful method to describe the characteristics of this pathologic condition with a rapid and less laborious approach.

Evaluation of DNA content by static cytometry in hypertrophic cardiomyopathy (HCM).

In the contexts of normal cardiac development in humans, the capability of mitosis is restricted to the intrauterine phase and a brief postnatal period. But various findings indicate that the final number of muscle cells may be increased by physiological and pathological stimuli which affect the heart also during adulthood. 1-3 The aim of this study is to determine variation in the capability of mitosis in hypertrophic myocardial fibrocells (HCM) using an image analyzer. We examined 4 cases of HCM and 5 controls. Samples were taken from the free walls of the atria, right and left ventricular free walls, and the ventricular septum, fixed in 10% forrnalin buffer and embedded in paraffin. Sections of 5 prn thickness were stained with hematoxylin-eosin by the Feulgen procedure. Densitometric tests were performed on the sections with a VIDAS image analyzer (Zeiss-Kontron) and DNA content (integrated optical density) and nuclear area of rnyocytes were evaluated. An average of 300 well-defined coplanar fibrocells were evaluated from hypertrophic myocardial areas. This method is particularly suitable because of the stechiometric binding with nuclear DNA. Integrated Optical Density (IOD) was evaluated in nuclei arranged in longitudinal sections. Ploidy was expressed as DNA index = ratio between peak DNA content of myocardial nuclei analyzed and peak reference lymphocytes. DNA index = 1 corresponds to diploidy, DNA index f 1 to aneuploidy. The results of our investigation are expressed as mean values and relative standard deviation. The level of p < 0.05 was selected as being statistically significant. We used the variance analysis test (F-test) to show the difference between the mean values observed compared with controls. Densitometric analysis showed an aneuploid content of the triploid type, indicating an increased cell proliferation, an expression of hyperplasia. The factors that induce hyperplasia in HCM are not yet known. The increase of nuclear area of myocytes, confirmed by nuclear duplication, which is particularly evident in the septum and in the ventricle walls, seems to result from the presence of hypertrophy of myocardial fibrocells. Cytometric analysis of normal heart myocardial biopsy samples has shown the presence of polypolidization in the nuclei with HCM while fibroblast and endothe-

DENSITOMETRY OF PAUTRIER'S MICROABSCESS CELLS IN CUTANEOUS T CELL LYMPHOMA

Background. Epidermotropic lymphoid T cell infiltrates are part of a continuous spectrum of lesions ranging from “benign” parapsoriasis to frank cutaneous T cell lymphoma (CTCL, mycosis fungoides). Either the clinical or histologic differentiation between these entities prove often difficult and the prognosis may be difficult to assess.