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Biomedical subjects

J A Litwin

Publications and source records attributed to J A Litwin.

At least 19 recordsLinked to original sources
PubMed2000

Maxillary sinus polyps secondary to dental extraction.

Polyps of the maxillary sinus were obtained from six patients who had reported upper tooth extraction with oroantral perforation prior to the development of symptoms, from 11 patients with chronic sinusitis, and from 12 patients with allergy. Histopathological features, scanning electron microscopy of the polyp epithelium and clinical data were compared in those groups of patients. The post-traumatic polyps differed from those of other aetiologies by showing the presence of granulomas, less numerous inflammatory cells with very few eosinophils, nearly normal surface epithelium (smaller surface area occupied by nonciliated epithelium, absence of epithelial squamous cells, normal frequence of goblet cells), rapid appearance of symptoms, and shorter duration of the disease. It seems that the specific characteristics of the injury-induced polyps results from a different mechanism of their formation, involving primarily abnormal mucosal repair and to a lesser extent an inflammatory process.

Adolescent↗
PubMed1999

Microvascular architecture of the human urinary bladder wall: a corrosion casting study.

The vascular system of the urinary bladder wall effectively performs its function in spite of considerable spatial changes due to the filling/voiding cycle. However, only a few studies have dealt with the microvascular architecture of the bladder wall and only two, using old-fashioned techniques, were devoted to the human bladder. This study presents the microvasculature of the human bladder wall visualized by scanning electron microscopy of vascular corrosion casts. Postoperative bladder specimens obtained from patients with advanced bladder tumors were filled with small amount (80 ml) of saline and perfused via at least four largest arteries with anticoagulant-containing saline followed by paraformaldehyde/glutaraldehyde fixative and Mercox resin. After polymerization of the resin, the vascular casts were macerated with potassium hydroxide, cleaned with formic acid and water and freeze dried. Only regions of the bladder wall distant to the tumor were examined in light and scanning electron microscopes. The almost empty state of the bladder was manifested by extensive folding of the mucosa and tortuosity of almost all vessels other than capillaries. The branches of main arteries and veins formed an adventitial/serosal plexus which directly supplied/drained the capillary network of the muscularis and sent long perpendicular vessels to the mucosal plexus. These vessels had straight or coiled course depending on whether they terminated at the top or at the base of the mucosal folds. The rich mucosal plexus followed the folds parallel to their surface and gave off short, straight, mostly perpendicular twigs communicating with the subepithelial capillary network. Apart from very few vascular interconnections between the mucosal plexus and the muscularis, the submucosa was generally avascular. The subepithelial capillary network showed extreme density and uneven contours of the capillaries, only in less folded areas of trigone and urethral orifice the network was looser and capillaries thinner. The capillary system of the muscularis was poorly developed. Due to its architecture, tortuosity, and coiling/uncoiling capabilities, the microvasculature of the human urinary bladder wall seems to efficiently accommodate changes associated with cyclic contraction and stretching. Disturbances in blood flow induced by overdistension of the bladder reported in several studies may be due to pressure of the urine affecting the patency of the vessels rather than to the spatial insufficiency of the vascular system.

Adult↗
PubMed1999

Immunocytochemical investigation of catalase and peroxisomal lipid beta-oxidation enzymes in human hepatocellular tumors and liver cirrhosis.

A significant reduction of catalase activity, a peroxisomal marker enzyme, occurs in human hepatic neoplasias, but no information is available on other peroxisomal proteins. We have studied by means of immunohistochemistry four specific proteins of peroxisomes (catalase and three enzymes of lipid beta-oxidation) in human hepatocellular tumors of various differentiation grades from adenoma to anaplastic carcinoma. In all tumors, except the adenomas, the tumor cells contained fewer peroxisomes than extrafocal hepatocytes and the reduction of antigenic sites in the tumor types generally correlated with the degree of tumor dedifferentiation as assessed by classical histopathological criteria. Two poorly differentiated tumors had no detectable peroxisomes at all. There were no major differences in the intensities of the immunocytochemical staining for all four studied peroxisomal antigens in different tumors, suggesting that the neoplastic transformation affects the biogenesis of the entire organelle and not merely the individual peroxisomal enzyme proteins. Some tumors exhibited a distinct peripheral distribution of peroxisomes. In cases with associated liver cirrhosis, the hepatocytes in the adjacent liver showed marked peroxisome proliferation, forming large perinuclear aggregates, occupying occasionally the entire cytoplasm. Taken together, our observations indicate that peroxisomes are significantly altered in both hepatocellular tumors and liver cirrhosis and, thus, could be responsible for some of the metabolic derangements observed in those disease processes.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1999

Architecture of blood vessels in human fetal gastric corpus: a corrosion casting study.

Vascular architecture of the gastric corpus was investigated in 16-24 wk human fetuses using a corrosion casting technique and the scanning electron microscopy. The general distribution of blood vessels seen in adults has already been established in the fetus, with three major vascular plexuses located in the serosa, submucosa and mucosa. The serosal plexus, supplied and drained by large extramural vessels, contained anastomosing, arcade-like arrays of arteries and veins with their branches piercing the muscularis and communicating with the compact submucosal plexus. Vertical arterioles and capillaries were sent by submucosal arteries to supply a very dense capillary plexus which surrounded the gastric pits and consisted of wide, sinusoidal vessels showing morphological manifestations of angiogenesis by intussusceptive growth. The plexus was drained by vertical venules emptying into submucosal veins. In contrast to the richly vascularized upper half of the mucosa, the lower half showed a relative paucity of blood vessels, probably due to the thinness of the fetal mucosa allowing an effective diffusion of oxygen and nutrients from the upper half. Neither arteriovenous anastomoses, nor end-arteries were found in the fetal stomach. Results of this study support one of the two existing models of mucosal vascularization in the human stomach: i.e. the model postulating the presence of short and long arterioles and two distinct, albeit interconnected capillary networks in the upper and lower zones of the mucosa respectively. In human fetuses, the latter network is absent; it probably develops by remodelling of the preexisting vertical capillaries in the last phase of pregnancy, prior to the onset of gastric gland function.

Adult↗
PubMed1998

Vascular architecture of human urinary bladder carcinoma: a SEM study of corrosion casts.

The vascular architecture of five advanced invasive papillary tumours of the urinary bladder was investigated using corrosion casting and scanning electron microscopy. The superficial vasculature was composed predominantly of capillary systems of two types: dense flat networks with numerous interconnections and tightly packed tortuous loops, forming multiple irregular folds that reflected the papillary morphology of the tumours. The capillaries were supplied and drained by numerous straight nonanastomosing arterioles and venules, which arose by way of multiple branching of larger vessels originating from the mucosal plexus of the bladder. Differences between the tumours in the spatial arrangement of these vessels probably reflect different growth dynamics. The intramural parts of the tumours contained a chaotic network of straight, uniform capillaries with numerous sprouts, which was very different from the superficial capillary system. It is postulated that different angiogenesis-targeted growth factors may be expressed in the phases of exophytic growth and muscularis invasion of the tumour, leading to the formation of different microvascular patterns.

Arterioles↗
PubMed1998

Microcirculation of human fetal posterior root ganglia: a scanning electron microscopic study of corrosion casts.

The vasculature of lumbar posterior root ganglia was investigated in human fetuses aged 17-24 weeks; using the corrosion casting technique and scanning electron microscopy. The arterial supply consisted of one main artery and occasional arterioles entering the ganglion at its pole and running axially, while the venous drainage was located at the periphery of the ganglion, thus indicating a centrifugal pattern of blood flow. The dense capillary network of the ganglion showed the roughly parallel course of the vessels in the central zone and an irregular arrangement in the peripheral zone where capillaries formed "nests", probably surrounding individual perikaryons of ganglionic cells. The capillaries had a sinusoidal character with numerous dilatations about twice the normal capillary size, as well as occasional larger vascular spaces resulting from capillary interconnections and suggesting the intussusceptive type of angiogenesis.

Capillaries↗
PubMed1998

Distribution of mast cells along and across successive segments of the rat digestive tract: a quantitative study.

Density of mast cells stained by Alcian Blue at pH 0.3 was measured in the successive segments and the successive layers of rat digestive tract using a semiautomatic computerized image analysis system. The results were calculated in a dual way: per area of the entire layer and per area of its connective tissue compartment, in which the mast cells were located (extremely small number of intraepithelial and intramuscular mast cells was not included in the analysis). The distribution of mast cells in the particular layers was rather uniform with exception of the fundus of glandular stomach, where they were located at two distinct levels: in the upper quarter of the mucosa and in its lowermost zone, with the layer inbetween being practically free of mast cells. The quantitative estimation of mast cell density in the successive segments of the digestive tract yielded a generally similar profile irrespectively of the way of calculating the results, with the highest overall densities being observed in the middle segments (stomach, jejunum). Especially high densities of mast cells per area unit of the connective tissue were found in the muscularis of glandular stomach and in the lamina propria of small intestine and cecum. The analysis of mast cell density in the successive layers of the particular digestive tract segments revealed no clear pattern when the results were expressed per area unit of the whole layer. Calculation of densities per area unit of the connective tissue showed that lamina propria contained the most numerous mast cells in the entire small and large intestine, moreover, a decreasing pattern of mast cell density across the wall (lamina propria>submucosa>muscularis) was observed in the jejunum, transverse colon and rectum, suggesting that the latter way of calculation more reliably reflects mast cell distribution, which may result from the joint influence of two factors: the distance from the lumen of the digestive tract and the density of nerve terminals in its wall.

Alcian Blue↗
PubMed1997

The architecture of internal blood vessels in human fetal vertebral bodies.

The internal vascular system of vertebral bodies was investigated in 17-24 wk human fetuses by acrylic dye injection and by corrosion casting/scanning electron microscopy. The regions of intervertebral spaces did not contain blood vessels. The radial metaphyseal vessels were at the stage of centripetal ingrowth into the vertebral body cartilage and their terminal, blindly ending segments had a form of cuff-like capillary plexuses. The anterolateral equatorial arteries communicating with the vessels of the ossification centre were only rarely found. The centre was usually supplied by 2 posterior (nutrient) arteries which branched into an arcade-like array of arterioles equipped with occasional sphincters and giving origin to a dense network of peripherally located capillaries. Numerous blind capillary buds formed the advancing border of the ossification centre. The veins usually accompanied the arteries. In the ossification centre the venous compartment consisted of sinuses drained by larger posterior veins. In the 17 wk fetus, an axial avascular area was observed in the place of notochord localisation, indicating the formation of a ring-shaped ossification centre around the notochord remnants at earlier stages of fetal development.

Corrosion Casting↗
PubMed1997

Distribution of eosinophils along and across successive segments of the rat digestive tract: a quantitative study.

Density of eosinophils stained by substrateless DAB reaction was measured in the successive segments and the successive layers of rat digestive tract using a semiautomatic computerized image analysis system. The results were calculated in a dual way: per area of the entire layer and per area of its connective tissue compartment, in which the eosinophils were located (extremely small number of intraepithelial and intramuscular eosinophils was not included in the analysis). The density of eosinophils in the successive segments of the digestive tract seemed to depend primarily on the time of contact between the contents and the wall of the segment, being the highest in regions of food/content retention (fundus of the stomach, cecum) and the lowest in regions of rapid passage (esophagus, pylorus, duodenum). When eosinophil density in the successive layers was compared, its gradual decrease in the successive layers (villi>lamina propria>submucosa>muscularis) was observed in almost the entire small intestine and lower values in submucosa compared to mucosa were also evident in the stomach, duodenum and small intestine. It seems that there is a decreasing gradient of chemoattractants for eosinophils dependent of the distance from the lumen and the contents of the digestive tract. However, this decreasing pattern appeared only when the density was calculated for the area of the connective tissue compartment suggesting that this method of calculation more reliably reflects the distribution of eosinophils and should be used in future quantitative studies on tissue eosinophils.

Animals↗
PubMed1996

Vascular architecture of the human fetal adrenal gland: a SEM study of corrosion casts.

The vascular architecture of adrenal glands was investigated in human fetuses aged from 16 to 24 weeks, using microcorrosion casts and scanning electron microscopy. The fetal adrenals showed an arrangement of blood vessels remarkably similar to that described in adult glands. There was a clear centripetal pattern from superficial arteries and their branches, via irregular capillaries of the subcapsular plexus and definitive cortex, and then via the radial sinusoids and venous sinuses of the fetal cortex, to the central vein. Rare medullary arterioles traversed the cortex to break up into small local capillary networks in the central region of the gland. Some superficial capillaries were drained by occasional subcapsular veins. No portal system was observed in the fetal adrenals.

Adrenal Glands↗
PubMed1995

Corrosion casting study on the vasculature of nasal mucosa in the human fetus.

BACKGROUND: The vasculature of the nasal mucosa in the human fetus so far has not been investigated morphologically by modern techniques. METHODS: Nasal blood vessels were studied in 18-21-week-old human fetuses by corrosion casting and scanning electron microscopy. RESULTS: The general vascular architecture was similar to that described for adult humans, with (1) a dense network of subepithelial capillaries, (2) a mucosal layer of larger vessels, predominantly veins, and (3) large arteries located near the perichondrium. Specific vessel types characteristic of the nasal mucosa and important for its functions in adults, such as cavernous veins or cushion veins, were, however, absent in the fetuses, although probable precursor forms of cushion veins could be observed. The arteriovenous anastomoses had the form of short bridges, and no tortuous or glomerular anastomoses present in the mature nasal mucosa were found. CONCLUSIONS: The underdevelopment of some vascular areas is postulated to reflect the functional immaturity of the respiratory system in the fetus.

Arteries↗
PubMed1995

Microvasculature of the dorsal mucosa of human fetal tongue: a SEM study of corrosion casts.

The vasculature of the dorsal mucosa of the tongue was investigated in 18-21 week human fetuses by corrosion casting and scanning electron microscopy. Microvascular systems of the fungiform, foliate and circumvallate papillae, albeit less complex, showed similarity to those described in children, while the capillary networks of the filiform papillae were not yet fully developed, having either a knot-like or cone-like form instead of the corolla-like pattern typical of the postnatal period. Morphological features suggesting angiogenesis included both capillary outgrowths characteristic of vascular sprouting and tiny holes in the vascular walls regarded as evidence of intussusceptive capillary growth. The subpapillary vascular network supplying and draining the papillary vessels was composed of the more superficial capillary bed and the deeper plexus of larger arterioles and venules.

Abortion, Spontaneous↗
PubMed1995

Immunocytochemical demonstration of peroxisomes in cultured Leydig cells: a decrease in testosterone secretion precedes reduction of peroxisomes.

Peroxisomes were visualized in primary cultures of mouse Leydig cells by light microscopic immunocytochemical demonstration of catalase and two enzymes of peroxisomal lipid beta-oxidation: acyl-CoA oxidase and 3-ketoacyl-CoA thiolase. Immunofluorescent peroxisomes had the form of granules, rods or short tubules located in the cytoplasm of Leydig cells. The amount of peroxisomes in the cells and the intensity of their fluorescence was similar irrespective of the antibody used. On days 2 and 4 of the culture, most Leydig cells contained very numerous, densely packed peroxisomes. On days 6 and 8, their number and fluorescence intensity gradually decreased. The parallel measurements of testosterone concentration in the culture medium revealed a sharp decline of androgen production between days 1 and 4 of the culture. The observed precedence of the decrease in testosterone production in relation to reduction of the peroxisome number suggests that a decrease in testosterone level or factors regulating androgen synthesis may influence degradation of peroxisomes.

Acetyl-CoA C-Acyltransferase↗
PubMed1995

Morphological heterogeneity of peroxisomes in cultured mouse Leydig cells.

Peroxisomes of different shapes were visualized in mouse Leydig cells from primary cultures by immunofluorescent demonstration of catalase and two peroxisomal lipid beta-oxidation enzymes, acyl-CoA oxidase and 3-ketoacyl-CoA thiolase. Apart from typical spherical profiles, rod-shaped, tubular and annular peroxisomes were also observed. The proportion between spherical and elongated forms varied from cell to cell; the latter forms seemed to occur more frequently in flattened cells spread on the glass in the course and after monolayer formation. On very rare occasions the Leydig cells contained small local networks of interconnected tubular peroxisomes, probably representing areas of peroxisomal reticulum, whose existence has been so far supported by substantial biochemical, but hardly any morphological evidence.

Acetyl-CoA C-Acetyltransferase↗
PubMed1994

Blood vessels in epiphyseal cartilage of human fetal femoral bone: a scanning electron microscopic study of corrosion casts.

Formation of intrachondral vessels (cartilage canals) in the proximal femoral epiphysis was studied in 13- to 22-week-old human fetuses using a corrosion casting technique and scanning electron microscopy. Several successive morphological stages of angiogenesis occurring inside the hyaline cartilage were distinguished. The process of cartilage vascularization starts with the formation of hairpin loops sent off from the perichondrial vascular network into the adjacent cartilage. A capillary glomerulus is then formed at the leading end, and the entire vascular unit grows in length, assuming a mushroom-like shape. Its further elongation is accompanied by a backward expansion of the capillary network which surrounds a pair of main vessels (arteriole and venule) like a manchette. The subsequent branching of such primary vascular units proceeds according to the same morphological patterns. The resulting tree-like vascular formations become interconnected via their lateral branches. This study clearly supports the invasion theory of cartilage canal formation.

Blood Vessels↗
PubMed1994

The vascular architecture of human fetal oviduct: a scanning electron microscopic study of corrosion casts.

Vascular architecture was investigated, in 18-21 week old human fetuses, for the first time with the use of corrosion casting and scanning electron microscopy, which offer high resolution and three-dimensional images of the vascular networks. The general arrangement of large vessels was similar to that described for the mature oviduct; however, the intramural vasculature of the muscular layer and mucosal folds consisted predominantly of capillary and sinusoidal networks. A characteristic feature of the fetal oviduct was a prominent sub-serosal venous plexus, which was most extensive in the isthmic segment. The relatively low degree of differentiation found in the fetal oviduct vasculature seems to reflect its functional immaturity.

Arteries↗
PubMed1994

The lung in closeview: a corrosion casting study on the vascular system of human foetal trachea.

The aim of this study was to examine the tracheal vasculature in 5 month human foetuses, and to determine whether it differs from that previously described by other authors for adult human trachea. The vascular bed was visualized using the technique of corrosion casting and examined by scanning electron microscopy. The arrangement of larger vessels: longitudinal tracheo-oesophageal arteries and veins, as well as their segmental branches running circumferentially in the intercartilaginous spaces, was similar to that observed in the trachea of adults. However, no blood sinuses reported to occur in the submucous venular plexus of the human trachea could be found in the foetuses. It is postulated that the possible functions of such sinuses acting as the capacitance system are related to the functional respiratory tract; hence, this vascular specialization is not yet developed in the foetus.

Blood Vessels↗