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Biomedical subjects

A C Levi

Publications and source records attributed to A C Levi.

At least 19 recordsLinked to original sources
PubMed2001

The development of the suprarenal gland: surgical and anatomical considerations.

BACKGROUND: Aim of this research is to study the situation and relationships of the adrenal gland in the first stage of development in order to give some contributes for the application of laparoscopic adrenalectomy; in the meantime we describe the series of the debate changes occurring in the constitution of the cortex and medulla. METHODS: Analysis of histologic slices of thoraco-abdominal and abdominal regions of human embryos and fetuses ranging from the fifth (12 mm CR) to the twentieth week (170 mm CR). RESULTS: At 12 mm CR an unique type of cells is present in the cortex; at 16 mm CR there are two different groups of cells. Sympathogonia enter into the cortex at 16 mm CR. The right adrenal gland seems enclosed into the liver and a ligament containing the middle adrenal vein reaches the vena cava inferior sulcus. The left adrenal gland, through the coelomic cavity, is in relationship with the stomach, the medial border of the spleen and the pancreatic body contained in the primitive dorsal mesogastrium. CONCLUSIONS: The timing of penetration of the ganglion cells into the cortex is defined as well as the hypothesis that the matrix of the fetal and definitive cortex is the same: moreover the study of the early development allows to understand the main characteristics of both the adrenal glands which are significant for a rational and differential laparoscopic approach.

Adrenal Glands↗
PubMed1998

Embryologic bases of extended radical resection in pancreatic cancer.

OBJECTIVE: To analyze whether an embryologic "rationale" exists to the clinical and anatomicopathological data that suggest the execution of extended resections in patients with pancreatic cancer. METHODS: Reconstruction of serial histological sections of 18 human embryos and fetuses regarding the pancreatic region; anatomical microdissections of two 9-month fetuses. RESULTS: The ventral and dorsal pancreatic buds can be identified until the eighth week of development. A close developmental relationship between the dorsal pancreas and the lymphatic and nervous structures in the dorsal mesogastrium is observed. Other lymphatic stations are exclusively related to the ventral pancreas. The posterior fusion of the dorsal mesogastrium is a late event in embryologic development. CONCLUSIONS: The complete fusion of the 2 pancreatic buds occurs later than previously reported in the literature. The close embryologic relations of these buds with the lymphatic and nervous peripancreatic structures may support the need for extended resections in patients with pancreatic cancer.

Fetus↗
PubMed1998

Anatomosurgical implications derived from an embryological study of the Scarpa's triangle with particular reference to groin lymphadenectomy.

OBJECTIVE: To clarify some anatomical controversies of the fascial structures and lymph node development of the inguinal region through an embryological study in relation to the surgical techniques of groin lymphadenectomy. METHODS: Sections of the femoral triangle belonging to four fetuses whose crown-rump (CR) length ranged from 70 to 310 mm, corresponding to a developmental age of 11 and 35 weeks, were studied. RESULTS: The femoral fascia is formed of one layer and is not divided into superficial and deep layers. The cribriform fascia has a morphogenetic origin different from that of the femoral fascia and it is defined by the thickening of the connective tissue filling the fossa ovalis and therefore would be more correctly named lamina cribrosa. The deep inguinal lymph nodes originate directly from the superficial lymphatic tissue located in the fossa ovalis. This last observation supports the fact that no lymph nodes are present beneath the femoral fascia distal to the lower margin of the fossa ovalis. CONCLUSIONS: The results of this study, from a surgical point of view, support the technique of total or radical inguinal-femoral lymphadenectomy with preservation of the femoral fascia and, from an anatomical point of view, resolve some of the contradictory statements reported in the anatomical literature regarding morphogenesis and terminology of the structures of the Scarpa's triangle. In addition, the present study provides useful anatomic and terminological landmarks to those surgical oncologists (gynecologist, urologist, dermatologist, etc.) dealing with malignant diseases requiring groin dissection practices. In addition, it could represent a useful background for a future more precise surgical terminology which represents a vital issue for institutional studies with multiple surgeons as well as for large multi-institutional studies.

Fascia↗
PubMed1996

Histopathology of the substantia nigra in Alzheimer's disease.

Histopathologic examination of the pars compacta of the substantia nigra of 17 patients with Alzheimer's disease showed Lewy bodies in six, neurofibrillary tangles in another six and only histologic changes that did not differ from age-matched controls in five patients. Four of the six patients with nigral Lewy bodies showed severe loss of neural cell bodies, reactive astrocytosis, gliosis and neuromelanin in macrophages and in the neuropile. By contrast, the loss of neuronal cell bodies in our patients without nigral Lewy bodies regardless of whether or not they also had nigral neurofibrillary tangles was no greater than what we observed in our age-matched controls. Quantitative cell counts confirmed our histopathologic estimates of neuronal loss. Our study and the findings of others show that the substantia nigra is often abnormal in Alzheimer's disease and that the abnormalities are rarely severe without nigral Lewy bodies.

Aged↗
PubMed1994

Mitochondrial abnormalities in nigral neurons of the marmoset and Macaca fascicularis treated with MPTP.

In a previous study we observed the processes determining the cellular death in nigral neurons of Macaca fascicularis and common Marmoset treated with MPTP. The purpose of this study is to consider, in substantia nigra neurons of the same animals, mitochondrial abnormalities caused by neurotoxin. Three Macaca fascicularis and 5 common Marmosets, respectively treated with 3 and 4 mg/kg of MPTP dissolved in saline + 10% ethanol, were suppressed by means of an i.v. injection phenobarbital. The substantia nigra, isolated from the mesencephalon, has been examined under Electron Microscope. Different mitochondrial abnormalities have been observed in nigral neurons: crystal abnormalities occur more frequently than other alterations. They are correlated with various degrees of mitochondrial enlargement. Dissolution of the matrix induces formation of spherical highly electron-dense inclusions of various volume and in different number; they are probably lipoprotein. Laminar bodies and myelin-like figures are determined by alterations of the external membrane. Particular roundish organules, placed near normal mitochondria, are limited by fragments of membrane with a granular material, occasionally flowing in the cytoplasm. The biochemical hypothesis concerning the genesis of the observed abnormalities is discussed in the present study.

Animals↗
PubMed1994

The aging substantia nigra: quantitative histologic study.

In this study, we estimated the amount of neuronal neuromelanin in hematoxylin and eosin sections of the pars compacta of the substantia nigra in 69 autopsied subjects, 14 to 100 years old. The mean area of cellular neuromelanin showed a curvilinear increase from 103 microns2 at age 14, to 600 at age 67 before dropping off to 328 at age 100 (R2 = +0.51, p < 0.00001). By contrast, the areal fraction or area of neuromelanin relative to the area of neuronal cell bodies showed a linear increase with age (r = +0.84, p < 0.00001). The latter and an increase in the percent of neuromelanin pigmented neuronal cell bodies from 83% at age 14 to almost 100% at age 65 and older (R2 = +0.61, p < 0.00001) accounted for the increasing mean area of cellular neuromelanin. By contrast, a decrease in the mean area of neuronal cell bodies (r = -0.63, p < 0.00001) and a decrease in the number of profiles of neuronal cell bodies (r = -0.51, p < 0.0001) explained the decrease of mean area of cellular neuromelanin beyond 67. Our findings support the hypothesis that an overload of neuromelanin is neurotoxic and emphasize the importance of using age-matched controls in histopathologic studies of the substantia nigra.

Adolescent↗
PubMed1994

Postnatal development of intestinal villi in the rat. Determination of villus size gradient.

The existence of the so called "Villus Size Gradient" (VSG) which defines the proportional decrease in height of intestinal villi from duodenum to ileum is well documented in adult animals and man. The aim of this study is to define whether the VSG is present since birth or, if not, when and why it appears. We have measured the height of intestinal villi in 25 rats: 5 at 1 day from birth, 5 at 5 days, 5 at 8 days, 5 at 15 days and 5 at 30 days. We have prepared histological slides of a duodenal, jejunal and ileal tract of each animal and measured the height of villi on microphotographs. At day 1 we observed a higher size of duodenal villi statistically significant with respect to jejunum and ileum, while at day 5 no differences were observed between the various intestinal tracts. The VSG become evident 8 days after birth progressively increasing to day 30. The predominance of duodenum present at birth is therefore probably due to the fetal developmental growth which is known to be more precocious in duodenum than in more distal tracts. Five days after birth the intestinal villi are equally developed, while in later ages the VSG appears. So we can conclude that the VSG is a consequence of luminal and humoral factors and not a predetermined event.

Analysis of Variance↗
PubMed1993

Arrangement of the anal striated musculature.

A study of the anatomy of the anal striated musculature is performed on 34 adult specimens to reconsider some debated morphologic aspects. The original "eight-shaped" arrangement of the fibers of the pubococcygeus is pointed out, suggesting a definite role of the muscle as a superior part of the continence muscular complex; the intermediate part seems to be formed by the puborectalis loop and the deep external anal sphincter, not always separable. Finally, the inferior portion is represented by the superficial sphincter, which shows anatomic behavior similar to that of the pubococcygeus.

Adult↗
PubMed1991

Development of the anal canal muscles.

The anal canal muscles development is studied in 18 human embryos. The external anal sphincter results to origin common with the urogenital sphincter from the cloacal sphincter. The muscle, after its appearance, is subdivided into two portions from a thin mesenchymal layer. Moreover, our embryologic study clearly confirms that the puborectalis muscle is a portion of the levator ani, its primordium being common with the ileo and the pubococcygeus muscles. The anal smooth musculature appears later than the striated one.

Anal Canal↗
PubMed1991

Modifications of the trophism of intestinal mucosa after intestinal and bilio-pancreatic diversion in the rat.

Morphofunctional alterations to the intestinal mucosa are influenced by three main factors: food, bilio-pancreatic secretions, intestinal hormones. In order to assess the importance of each one, histological and histochemical tests were performed on different segments of intestine taken from rats which were sacrificed one month after the following procedure: gastrojejunal anastomosis on a Roux loop (Model I); same procedure plus biliopancreatic bypass into the jejunum (Model II). When compared to the controls, Model I duodenum samples revealed hypertrophy of the entire wall with "bundles" of villi, while Model II samples showed a clear hypotrophy and reduction in the number of duodenal villi. To such modifications of the duodenum correspond longer, thinner villi in the other bowel segments, particularly in the jejunum and distal ileum. These results suggest that the predominant trophic effect derives from contact with biliopancreatic secretions at a proximal level. The modifications of the duodenal mucosa appear to regulate the trophism of the distal segments probably by the secretion of distant acting enterohormones.

Adaptation, Physiological↗
PubMed1989

Effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on ultrastructure of nigral neuromelanin in Macaca fascicularis.

In neurons of the substantia nigra (SN) of Macaca fascicularis the administration of parkinsongenic doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) caused morphological changes of the neuromelanic granules. Under light microscopy, the granules appeared more dispersed and larger. Electron microscopy revealed coalescence of granules in large masses with loss of the electrodense component. Phagocytosis of neuromelanin by glial cells was also observed. In several neurons the neuromelanic changes were evident in the presence of morphologically intact mitochondria. These data suggest an interaction between MPTP and neuromelanin that may have relevance to the nigrotropic toxicity of MPTP and are in agreement with observations on neuromelanin in parkinsonian patients.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1986

Neuromelanic pigment in substantia nigra neurons of rats and dogs.

The presence of neuromelanic pigment in neurons of the rat substantia nigra (SN) is a matter of controversy. The presence of neuromelanin in the SN of 15--24-month-old rats was investigated by electron microscopy (EM) and the findings compared to the morphology and distribution of neuromelanin in SN of dogs. In the rat, EM examination revealed a few small, evenly distributed neuromelanic granules in only 5% of nigral neurons. Dogs of 1 year of age showed a similar pattern; however, SN from adult and aged dogs exhibited abundant and larger neuromelanin granules which were also detectable by light microscopy. It is concluded that scanty neuromelanin is detectable by EM in rat SN and that the content of this pigment increases with age. The documented paucity of neuromelanin in rat SN neurons may explain why higher doses and longer treatment with MPTP is required in rats to obtain biochemical and behavioral signs of nigrostriatal dysfunction in this species.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1982

Preliminary observations on the neuromelanic pigment in the substantia nigra nucleus of the cat.

The AA. study the behaviour of neuromelanic pigment in the substantia nigra of cats' mesencephalon. To this aim they suppress a first group of animals with MgSO4; a second group with a substance whose action is narcotic and curare-like. They carry out the observations on mesencephalon microtomic sections, some stained with hematoxylin, some treated with PAS reaction and some with Sudan Black. The results are: 1)- in the perikaryon of substantia nigra pars compacta neurons of cats suppressed with MgSO4, the pigment, absent in the early age of life, appears in adult age. It is characterized by brownish-yellow granulations, either scattered or clustered together. This finding is substantially similar to that observed in dogs' substantia nigra. 2)- The substantia nigra neurons of the mesencephalon taken from cats suppressed with a curare-like substance, appear instead, almost wholly, without the peculiar neuromelanic granulations. However intracytoplasmic bodies stained with hematoxylin and PAS positive, can be observed. In order to establish the morphological and histochemical events which occur in the substantia nigra neurons in depigmentation induced in this way the AA. consider further investigations absolutely necessary.

Aging↗
PubMed1979

Ultrastructure of neuromelanin granules in dog substantia nigra at different ages.

The Authors study through ultrastructural observations the sequence of processes concerning the appearance and the depositing of the neuromelanic pigment in the neurons of dog mesencephalic substantia nigra nucleus at different ages. The results are as follows: in the one year old dog, in a low percentage of lysosome-like oval organelles, few masses, strongly electron-dense, appear on the matrix. In the five year old dog, these masses are deposited and increased in quantity inside many more organelles. In the specimens extracted from older dogs, these organelles, characterized moreover by the presence of lipidic globules, merging in groups, became larger and more irregular. The Authors discuss the results obtained with the ultrastructural observation, compared with those obtained with the optical methods.

Aging↗