Areas Of Rarefaction Research Articles

Pathology of periportal fibrosis involution in human schistosomiasis.

Optical and electron microscopical evidences of focal matrix degradation were frequently seen in liver sections of periportal fibrosis caused by schistosomiasis mansoni in man. The material came from 14 wedge hepatic biopsies taken from patients with chronic advanced hepatosplenic disease and undergoing operations for the relief of portal hypertension. Besides the presence of focal areas of rarefaction, fragmentation and dispersion of collagen fibers, the enlarged portal spaces also showed hyperplasia of elastic tissue and disarray of smooth muscle fibers following destruction of portal vein branches. Eggs were scanty in the tissue sections, and matrix degradation probably represented involuting changes related to the progressive diminution of parasite-related aggression, which occurs spontaneously with age or after cure by chemotherapy. The changes indicative of matrix degradation now described are probably the basic morphological counterpart of periportal fibrosis involution currently being documented by ultrasonography in hepatosplenic patients submitted to curative chemotherapy.

Lysosomes as key organelles in the pathogenesis of prion encephalopathies.

The causation, structural origin, and mechanism of formation of spongiform lesions in transmissible encephalopathies are unknown. We have used immunogold electron microscopy to locate ubiquitin conjugates, hsp 70, and beta-glucuronidase (markers of the lysosomal compartment) and prion protein (PrP) in both control and scrapie-infected mouse brain. In scrapie-infected brain, lysosomes and lysosome-related structures (multivesicular and tubulovesicular dense bodies) are present in abnormally high numbers in neuronal cell processes. These structures contain PrP, together with the lysosomal markers ubiquitin conjugates, hsp 70, and beta-glucuronidase, which could also be identified spilling from tubulovesicular dense bodies into areas of early rarefaction in neuronal processes; we suggest that these areas of rarefaction are the precursor lesions of spongiform change. We advance the hypothesis that spongiform change is brought about by cytoskeletal disruption in neuronal processes caused by liberation of hydrolytic enzymes from lysosomes overloaded with the abnormal isoform of PrP (PrPsc). We suggest that the lysosomal system is probably acting as the bioreactor for processing of normal PrP to the abnormal isoform. The continuous production of increasing quantities of abnormal PrPsc in lysosome-related bodies will eventually cause disruption of the lysosomal membrane with destruction of the neuronal cytoskeleton and the initiation of vacuolation. Later, death of the cell will be associated with release of the PrPsc isoform into the extracellular environment. Repeated rounds of phagocytosis, lysosomal biogenesis of PrPsc, lysosomal membrane rupture, hydrolytic enzyme release, and neuronal lysis will lead to an exponential increase in cell damage and cell death.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological features of collagen degradation in advanced hepatic schistosomiasis of man.

Optical and electron microscopical evidences of focal matrix degradation were frequently seen in liver sections taken from patients with periportal ("pipe-stem") fibrosis caused by schistosomiasis mansoni. Besides the presence of focal areas of rarefaction, fragmentation and dispersion of collagen fibers, the enlarged portal spaces also showed hyperplasia of elastic tissue and disarray of smooth muscle fibers following the destruction of portal vein branches. Ultrastructural changes represented by focal lytic and/or electron dense alterations of collagen fibrils were similar to those first seen in experimental material and designated as "chronic collagen degradation". Elastin and related microfibrils were also affected by focal condensation, fragmentation, distortion and dissolution. Schistosome eggs were scanty in the tissue sections examined. Matrix degradation represented involuting changes related to the progressive diminution of parasite aggression, which occurs spontaneously with age or after cure by chemotherapy. Changes of focal matrix degradation now being described represent the basic morphological counterpart of periportal fibrosis involution documented clinically, especially by ultrasonography, in patients with hepatosplenic schistosomiasis submitted to curative chemotherapy.

先天性股関節脱臼における骨頭核の変形 骨幹端の変化との関連について

165 hips in 132 patients with congenital dislocation of the hip wete reviewed to analyse the radiological course of the capital femoral epihysis assosiated with metaphyseal changes. The mean age at late follow-up was 6.8 years (range, 5-15 years).Epiphyseal deformities wete classified into three types according to the extent of the defect, and metaphyseal changes, which were area of rarefaction, medial beaking and sagging rope sign, were sought in the early period after reduction.Then the late radiologic appearance of the femorel head and neck was graded to the three classes by modified thomas's system.89 hips wete recognized one of three types of the epiphyseal deformities. 32 hips of 89, in whcih epiphyseal deformities appeared, had one or more metaphyseal changes and were gradaed as poor and fair on the late radiologic apparance. All of 16 hips with poor results had early metaphyseal changes.It is thought that early metaphyseal changes on the epiphyseal deformities may be correlated with the final radiolgic result.

Ultrastructure of hypertensive rat aorta. Increased basement membrane-like material.

To determine the effect of elevated blood pressure on the ultrastructure of rat aorta, hypertension (average mean pressure 163 +/- 17 mm Hg) was produced by suprarenal aortic coarctation. After 3 weeks, the subendothelium of the hypertensive thoracic aorta showed significantly increased volume measurements for mononuclear leukocytes and basement membrane-like material compared with the sham-operated control group. Focal areas of rarefaction of the subendothelial extracellular material were associated with the nearby presence of mononuclear leukocytes. None of these alterations were found in the normotensive abdominal aorta. The tunica media of hypertensive thoracic aorta also contained significantly increased basement membrane-like material. This new finding in an animal hypertension model is the direct result of the quantitative morphological approach employed in this study. In some rats, the partially constricting aortic ligature compromised the right renal artery leading to ischemic atrophy of the right kidney and hyperreninemia in addition to hypertension. In this group, excluded from the previous analysis and evaluated separately, subendothelial thickening and accumulation of basement membrane-like material in the thoracic aorta were greatly increased compared with the control group and other hypertensive rats. This result could not be attributed to an effect of blood pressure alone and might have been caused in part by humoral factors. Basement membrane accumulation appears to be an important early response of the arterial wall to hypertension or other factors in this rat model.

The nature of humeral pseudocysts.

In an effort to define the nature of the humeral pseudocyst, we examined a large number of macerated specimens. The area of rarefaction, located in the lateral aspect of the proximal humerus, may be a prominent radiographic finding in young individuals. In older individuals, with loss of trabecular bone in the proximal portion of the humerus, a less obvious rarefaction is present. Precise radiographic features allow differentiation of this normal finding from significant lesions in this region.

Reading the radiograph: A comparison of viewing techniques

The presence or absence of an area of periapical pathosis as exemplified by an area of rarefaction in 260 cases selected at random was determined by viewing a single radiograph of each case using three viewing techniques. Six examiners viewed the radiographs independently. They agreed with one another about 50% of the time. Holding the radiograph up to the view box was found to be more accurate than either projecting the image on a screen or viewing the radiograph through a magnifier viewer. By using the three techniques, individual examiners were able to agree with themselves an average of 68.8% of the time. The presence or absence of an area of periapical pathosis as exemplified by an area of rarefaction in 260 cases selected at random was determined by viewing a single radiograph of each case using three viewing techniques. Six examiners viewed the radiographs independently. They agreed with one another about 50% of the time. Holding the radiograph up to the view box was found to be more accurate than either projecting the image on a screen or viewing the radiograph through a magnifier viewer. By using the three techniques, individual examiners were able to agree with themselves an average of 68.8% of the time.

Chronic Candida Arthritis in Leukemic Patients

SIR-We read with interest the report of Fainstein et al. [1] as well as their review on candida arthritis in patients with cancer. Since the data on the pathology of candidal arthritis in humans are very limited, we would like to draw attention to a case not included in their review; it involved a patient with acute myeloblastic leukemia [2]. Because of misdiagnosis despite positive joint cultures, this patient had a chronic arthritis of the knee due to C. albicans that evolved over a nine-month period during which there was no specific treatment. A synovial biopsy was performed four months after appearance of the first symptoms and revealed nonspecific histologic signs of inflammation and no visible fungi. Radiographs of the joint performed eight months after onset revealed patchy areas of rarefaction in the femoral epiphysis. There was transient improvement when amphotericin B was started eight months after onset, but the patient soon died of his underlying disease. At autopsy there was evidence of disseminated visceral fungal infection presenting as pseudotumoral nodules. The affected knee joint showed localized cartilaginous erosions; microscopic examination showed that these were riddled with numerous fungal filaments. The adjacent bone showed atrophy but no foci of infection. This case of a chronic C. albicans arthritis in a leukemic patient shows that radiologic abnormalities as well as cartilaginous lesions may develop with time. This observation is in contrast to the lack of cartilage and bone involvement observed by Fainstein et al. in their patients with acute C. albicans arthritis. In the latter group the lesions remained surprisingly limited despite the incompetence of the patients' host defenses.

Ultrastructural lesions of bile ducts in primary biliary cirrhosis: A comparison with the lesions observed in graft versus host disease

Intrahepatic bile duct destruction is a characteristic feature of primary biliary cirrhosis and hepatic graft versus host disease. Lymphocytotoxicity against antigens on the surface of biliary cells is one of the cell mediated immune mechanisms debated in the pathogenesis of persistent bile duct destruction during primary biliary cirrhosis. Immune complex injury has also been hypothesized. In graft versus host disease, damage to bile duct cells is also believed to be due to a cytotoxic reaction of the grafted lymphoid cells against the host histocompatibility antigens, and immune complex deposition is likely to occur. The aim in this comparative ultrastructural study of intrahepatic bile ducts in 10 patients with primary biliary cirrhosis and six patients with hepatic graft versus host disease was to investigate whether identical or different ultrastructural lesions were detected in both diseases. Features of conspicuous necrosis of biliary cells, including cytolysosomes, apoptosis, and basement membrane disruption, were observed in both diseases. Numerous lymphocytes established close membrane contacts with biliary cells, especially with the necrotic ones. They had cytoplasmic pseudopods, and some of them displayed a uropod or contained lysosomal vesicles. Abnormalities of the bile duct basement membrane, also observed in both diseases, included thickening or multilayering and numerous lucent areas of rarefaction often containing osmiophilic inclusions. The striking similarity of the ultrastructural lesions in both diseases provides an additional morphological argument to suggest that certain common pathogenic mechanisms might be involved in the destruction of bile ducts in primary biliary cirrhosis as well as in hepatic graft versus host disease.

Furcation canals in the human mandibular first molar

The presence of lateral canals from the floor of the pulp chamber to the furcation region has been demonstrated radiographically after obliteration of the root canal. Furthermore, pulpal inflammation can cause areas of rarefaction in the interradicular bone which normally resolve after routine endodontic procedures. These occurrences seem to indicate that there are direct avenues of communication between the pulp and periodontal tissues. In order to investigate this further, 100 human mandibular first molars were used in an in vitro study to determine the incidence of lateral canals in the furcation region.

A dynamic analysis of an elastic model of the human head

The determination of possible locations of brain damage caused by the generation of tensile pulses in the brain for axisymmetric impact is investigated. The head is modeled as a spherical fluid-filled shell and as a prolate ellipsoid of revolution. In the latter case both cavitating and noncavitating central fluids were used. The models are analyzed using a two-dimensional Lagrangian, finite difference computer computation. Results show rarefactions occur in the fluid both adjacent to and opposite to the loading point. The elliptical geometry increases the maximum tensile value and the occurrence of cavitation causes major modification of the levels in the rarefaction areas.

Electrophoretic differentiation of radicular cysts and granulomas

Polyacrylamide-gel electrophoresis was used for differential diagnosis of radicular cysts and granulomas. Root canal fluids were aspirated from forty anterior teeth with radiographic evidence of periapical pathosis, and from one pulpless anterior tooth with no radiographic evidence of periapical pathosis. Endodontic therapy was performed on all the teeth, and all the periapical lesions were surgically removed. The lesions were examined histologically, and the histopathologic diagnoses were then compared with the electrophoretic patterns. Analysis of the root canal fluids showed the following: (1) An albumin pattern was found in all thirty-one of the cases diagnosed histologically as being granulomas. The same pattern was also found in the case of the pulpless tooth without an area of rarefaction. (2) In eight of the nine cases diagnosed histologically as cysts, there was a much more intense albumin pattern and other patterns in the globulin regions. In the one case of a cyst that was misdiagnosed, the apical portion of the canal was calcified and the cyst lumen was never penetrated.

Endodontic success—Who's reading the radiograph?

Success and failure in 253 cases selected at random were determined by mounting the films and having six examiners read them, independently and without consulting one another. They agreed on fewer than half of the cases. When the question was only one of determining whether or not an area of rarefaction was present on one film, the agreement was still less than half. Upper molars gave the greatest percentage of disagreement, but all the other teeth gave large percentages of disagreement also.

Myxoma of the mandible with a 35 year follow-up: Mr T. G. Scott's case

Summary A case of myxoma of the mandible has been followed for a 35-year period. The tumour recurred rapidly after attempts at excision and became painful. Prolonged clinical remissions (approximately 20 years and 10 years respectively) followed radiotherapy. Radiological evidence of areas of rarefaction in the jaw has persisted for 35 years in spite of treatment, but at present the lesion is symptomless.

Guidelines for the prevention of fracture of root canal instruments

1. Stainless steel reamers and files are preferable to carbon steel instruments because, while they may bend under excessive torque, they are less likely to break. 2. Root canal instruments should be examined both before and after use to make certain that the blades are regularly aligned. Too little or too much space between the blades is an indication that the instrument has been under strain and may break. 3. The smaller sizes of reamers and files (Nos. 10 to 30) should not be used more than twice (that is, instrumentation for more than two root canals). Rubber stops of different colors attached to the instrument are a convenient means of indicating how many times it has been used. 4. Dull instruments are likely to become lodged against dentine instead of cutting, and this promotes the chances of breakage. 5. Files break more often from the torque used in gaining a purchase on the dentine than from the act of filing against dentine. The degree of torque applied should be minimal. 6. Reamers should be twirled back and forth between the thumb and fingers, never exceeding a 180 degree are. 7. Instruments should be used in sequence of sizes, without ever skipping a size. 8. Because of the slight difference in diameter between a reamer and a file of a given size, both types of instrument should be used in narrow canals. Smaller stepwise increments in width will accrue than if either reamers or files alone are used, thus minimizing breakage of instruments. 9. Debris should be removed between the blades from time to time while one is operating with the same instrument in the root canal, as the accumulated debris retards cutting and so predisposes the instrument to breakage. 10. All root canal instruments should be used in a wet canal, preferably one which has been flooded with sodium hypochlorite, to facilitate cutting and thereby prevent breakage. 11. Chemical agents should be used along with instrumentation when necessary to facilitate cutting of dentine. 12. Where an instrument has been broken in the root canal, the prognosis is more favorable if an area of rarefaction is not present at the time of the accident.

The use of the pulpal space of a tooth in the conservative treatment of a large area of rarefaction

The use of the pulpal space of a tooth in the conservative treatment of a large area of rarefaction

Lucent Lesion in the Femoral Neck

Dr. Joseph T. Ferrucci, Jr.: This patient, a 30-year-old surgeon, noted the sudden onset of pain in his left hip while descending a staircase four months prior to admission. The pain persisted and was slightly aggravated by extremes of motion. Night pain occasionally occurred. A roentgenogram six weeks prior to this admission revealed a lesion in the left femoral neck. Aspirin was administered with considerable relief of symptoms. The physical examination and laboratory studies were not remarkable, and this examination of the hip was performed (Figure). <h3>Discussion</h3> Dr. Laurence L. Robbins: Dr. Dreyfuss, do you have any ideas about this? Dr. Jack R. Dreyfuss: There is an area of rarefaction in the intertrochanteric region somewhat nearer the lesser trochanter. There is no periosteal reaction or sclerosis, and I do not see any other lesions. Actually, this is a fairly large area of lucency, measuring over 4 cm in length. It

Endodontic success—A reappraisal of criteria: Part II

An attempt has been made to correlate clinical, histologic, and roentgenographic observations of endodontically treated teeth in order to focus attention on the inadequacies of the roentgenogram as the sole criterion of treatment success. Definitions and interpretations of success vary among clinicians, and most often the roentgenogram is used as the sole criterion of success. Clinical observations, such as the persistence of pain, swelling, and the development of a fistula, are seldom included as additional criteria. Roentgenographic interpretations of radiolucencies present many fallibilities. These are usually produced by differences in vertical and horizontal angulation of the roentgen beam. Systemic and local constitutional disorders often simulate periapical radiolucencies that are not of endodontic origin. Periodontal disease often causes roentgenographic lesions that are mistaken for evidence of endodontic treatment failure. These lesions develop either before or after endodontic treatment. Differences in the length of observation time used for the evaluation of success can produce variations in the rates of success or failure. Using the roentgenogram as the only criterion of success in cases in which no radiolucency developed in teeth without a region of rarefaction, we observed a success rate of 92.7 per cent in 1,200 cases within a period of 6 months. After a period of 2 years the success rate was 88.7 per cent in 500 cases. This difference was statistically significant. In cases of teeth with radiolucencies in which a decrease in the size of the area was viewed as an indication of success, there was no difference between a 6 month (75 per cent) and a 2 year (77 per cent) follow-up. When complete bone regeneration, as visualized on the roentgenogram, was used as the standard of success, our success rate was 39.2 per cent in 365 teeth after an observation period of 2 to 10 years. Failures as manifested by roentgenographic evidence usually will occur within 2 years, whereas the clinical symptoms of pain, swelling, and development of a fistula will occur during treatment or within the first few months after treatment. The teeth of patients with persistent pain during or immediately after treatment are often resected or extracted. This group is seldom included in the analysis of endodontic failures. Histologic sections of teeth, with and without areas of rarefaction, that were extracted because of pain occasionally revealed the presence of undisclosed accessory or lateral canals. However, pain was also present in a similar number of cases in which there were no accessory canals. Furthermore, necrotic tissue was observed in many of these canals with no clinical symptoms of pain. In endodontically treated teeth with periapical radiolucencies, there is a definite correlation with histologic findings, whereas no such correlation exists in teeth without periapical radiolucencies. This lack of correlation is especially true in the case of teeth with necrotic pulps. Histologic evidence of chronic inflammation in the periapical tissues of teeth with normal roentgenographic findings has been observed invariably in both animal and human teeth with necrotic pulps. Cysts and granulomas developed in the periapical region following pulp extirpation in a number of cases that did not exhibit radiolucent areas before or after treatment. Most of the histologic sections of periapical tissues of teeth with areas of rarefaction revealed granulomas and cysts in equal distribution. Scar tissue in the periapical region was found in only two of 100 specimens examined after treatment. The small incidence of cases with scar tissue in the periapical area does not justify the conclusion that healing occurs with scar tissue formation merely because an area appears smaller on a follow-up roentgenogram. We have observed that large areas of radiolucency can also contain fibrous tissue following endodontic therapy in a similar percentage of cases. Large, small, arrested, or reduced areas of rarefaction all contain the same inflammatory cells. Most radiolucencies, whatever their size may be, are either granulomas or cysts. We have proposed a hypothesis to show how a cystic lesion can heal following a nonsurgical or conservative endodontic procedure, and we have offered new and more realistic criteria of successful endodontic therapy, based on clinical, histologic, and roentgenographic evaluation.

Endodontic success—A reappraisal of criteria: Part I

Abstract An attempt has been made to correlate clinical, histologic, and roentgenographic observations of endodontically treated teeth in order to focus attention on the inadequacies of the roentgenogram as the sole criterion of treatment success. Definitions and interpretations of success vary among clinicians, and most often the roentgenogram is used as the sole criterion of success. Clinical observations, such as the persistence of pain, swelling, and the development of a fistula, are seldom included as additional criteria. Roentgenographic interpretations of radiolucencies present many fallibilities. These are usually produced by differences in vertical and horizontal angulation of the roentgen beam. Systemic and local constitutional disorders often simulate periapical radiolucencies that are not of endodontic origin. Periodontal disease often causes roentgenographic lesions that are mistaken for evidence of endodontic treatment failure. These lesions develop either before or after endodontic treatment. Differences in the length of observation time used for the evaluation of success can produce variations in the rates of success or failure. Using the roentgenogram as the only criterion of success in cases in which no radiolucency developed in teeth without a region of rarefaction, we observed a success rate of 92.7 per cent in 1,200 cases within a period of 6 months. After a period of 2 years the success rate was 88.7 per cent in 500 cases. This difference was statistically significant. In cases of teeth with radiolucencies in which a decrease in the size of the area was viewed as an indication of success, there was no difference between a 6 month (75 per cent) and a 2 year (77 per cent) follow-up. When complete bone regeneration, as visualized on the roentgenogram, was used as the standard of success, our success rate was 39.2 per cent in 365 teeth after an observation period of 2 to 10 years. Failures as manifested by roentgenographic evidence usually will occur within 2 years, whereas the clinical symptoms of pain, swelling, and development of a fistula will occur during treatment or within the first few months after treatment. The teeth of patients with persistent pain during or immediately after treatment are often resected or extracted. This group is seldom included in the analysis of endodontic failures. Histologic sections of teeth, with and without areas of rarefaction, that were extracted because of pain occasionally revealed the presence of undisclosed accessory or lateral canals. However, pain was also present in a similar number of cases in which there were no accessory canals. Furthermore, necrotic tissue was observed in many of these canals with no clinical symptoms of pain. In endodontically treated teeth with periapical radiolucencies, there is a definite correlation with histologic findings, whereas no such correlation exists in teeth without periapical radiolucencies. This lack of correlation is especially true in the case of teeth with necrotic pulps. Histologic evidence of chronic inflammation in the periapical tissues of teeth with normal roentgenographic findings has been observed invariably in both animal and human teeth with necrotic pulps. Cysts and granulomas developed in the periapical region following pulp extirpation in a number of cases that did not exhibit radiolucent areas before or after treatment. Most of the histologic sections of periapical tissues of teeth with areas of rarefaction revealed granulomas and cysts in equal distribution. Scar tissue in the periapical region was found in only two of 100 specimens examined after treatment. The small incidence of cases with scar tissue in the periapical area does not justify the conclusion that healing occurs with scar tissue formation merely because an area appears smaller on a follow-up roentgenogram. We have observed that large areas of radiolucency can also contain fibrous tissue following endodontic therapy in a similar percentage of cases. Large, small, arrested, or reduced areas of rarefaction all contain the same inflammatory cells. Most radiolucencies, whatever their size may be, are either granulomas or cysts. We have proposed a hypothesis to show how a cystic lesion can heal following a nonsurgical or conservative endodontic procedure, and we have offered new and more realistic criteria of successful endodontic therapy, based on clinical, histologic, and roentgenographic evaluation.

1261. Development of a high-temperature molten-lithium pump: R W Kelly et al,J Eng Power,88(1), 1966, 13–21

The determination of possible locations of brain damage caused by the generation of tensile pulses in the brain for axisymmetric impact is investigated. The head is modeled as a spherical fluid-filled shell and as a prolate ellipsoid of revolution. In the latter case both cavitating and noncavitating central fluids were used. The models are analyzed using a two-dimensional Lagrangian, finite difference computer computation. Results show rarefactions occur in the fluid both adjacent to and opposite to the loading point. The elliptical geometry increases the maximum tensile value and the occurrence of cavitation causes major modification of the levels in the rarefaction areas.