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Sarkar K, Sarkar S, Deb BC, Shah WA, Rashid M, Nagra JS, Panda S, Naik TN, Manna B. HIV makes its way in the islands of the Bay of Bengal (Andaman and Nicobar), India. J Infect 1994; 29:116-8. [PMID: 7963630 DOI: 10.1016/s0163-4453(94)95492-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Panda S, Sarkar S, Mandal BK, Singh TB, Singh KL, Mitra DK, Sarkar K, Tripathy SP, Deb BC. Epidemic of herpes zoster following HIV epidemic in Manipur, India. J Infect 1994; 28:167-73. [PMID: 8034996 DOI: 10.1016/s0163-4453(94)95620-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Since 1989, injecting drug use (IDU) related HIV infection has affected thousands of young adults in Manipur, a north eastern state of India bordering Myanmar following a similar kind of epidemic in adjoining countries like Thailand and Myanmar. During a clinical surveillance of a group of HIV positive IDUs for a natural history study at Manipur, herpes zoster (HZ) emerged as the most specific early HIV related illness (positive predictive value of 100%) in patients belonging to the age group of 12-45 years. Data collected from the dermatology departments of the two main hospitals of the state revealed that there had been an epidemic of HZ since 1990 (rate of 1990 being 11.3/1000 compared to 6.5/1000 in 1989, P value < 0.0001) among males of 12-45 years. The epidemic of HZ has been attributed to the preceding epidemic of IDU related HIV in the same age and gender group occurring 1 year earlier. HZ should be recognised as a marker condition similar to tuberculosis indicating the necessity of screening for HIV in regions where the dual problem of IDU and HIV exist in young adults.
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Sarkar AK, Ghosh AK, Biswas K, Roy BS, Sarkar K. Glycogen storage disease. Indian Pediatr 1994; 31:234-6. [PMID: 7875858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Hesselroth T, Sarkar K, van der Smagt P, Schulten K. Neural network control of a pneumatic robot arm. ACTA ACUST UNITED AC 1994. [DOI: 10.1109/21.259683] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sett R, Sarkar K, Das PK. Macrophage-directed delivery of doxorubicin conjugated to neoglycoprotein using leishmaniasis as the model disease. J Infect Dis 1993; 168:994-9. [PMID: 8376846 DOI: 10.1093/infdis/168.4.994] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The antileishmanial potency of doxorubicin conjugated to mannose-human serum albumin (man-HSA) was tested in experimental visceral leishmaniasis. Conjugation of doxorubicin did not decrease the affinity of the neoglycoprotein for the macrophage mannose receptor. Conjugated doxorubicin eliminated intracellular amastigotes of Leishmania donovani in peritoneal macrophages almost 12.5 times more efficiently than did the free drug and greatly reduced and possibly eliminated splenic intracellular parasites in four consecutive dosages at 5 micrograms/kg/day for 45 days. Free drug at a similar dose had little effect. The leishmanicidal effect of doxorubicin conjugate can be prevented by competitive inhibitors such as man-HSA or mannan and inhibitors of receptor-mediated endocytosis such as colchicine and monensin. These results not only indicate the potential of doxorubicin as an effective chemotherapeutic agent for leishmaniasis but also establish the use of mannosylated neoglycoprotein as a drug carrier in the therapy of macrophage-associated diseases.
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Sarkar K, Meneveau C. Gradients of potential fields on rough surfaces: Perturbative calculation of the singularity distribution function f( alpha ) for small surface dimension. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1993; 47:957-966. [PMID: 9960092 DOI: 10.1103/physreve.47.957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Abstract
Pain originating in periarticular soft tissues of the shoulder is a common clinical problem among the aged patients of both sexes, but it has become increasingly frequent in young individuals because of a health-oriented life style. In the past year, a considerable progress has been made in diagnosing these conditions, especially with the aid of magnetic resonance imaging. Our understanding of the pathogenesis of these conditions, however, has advanced very little, and we hope that more efforts will be devoted in the future to elucidate how the periarticular soft tissues of the shoulder react to diverse injuries they are exposed to.
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Uhthoff HK, Sarkar K. Classification and definition of tendinopathies. Clin Sports Med 1991; 10:707-20. [PMID: 1934093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The authors have classified tendinopathies into two categories. The majority of the tendinopathies are in the primary category in which lesions arise in the substance of the tendon. The authors emphasize that not all tendinopathies are degenerative in nature. Some primary tendinopathies are reactive, such as calcifying tendinitis.
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Uhthoff HK, Sarkar K. Surgical repair of rotator cuff ruptures. The importance of the subacromial bursa. THE JOURNAL OF BONE AND JOINT SURGERY. BRITISH VOLUME 1991; 73:399-401. [PMID: 1670436 DOI: 10.1302/0301-620x.73b3.1670436] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We examined biopsy specimens obtained during surgery on 115 patients with complete rotator cuff rupture. The vascularised connective tissue covering the area of rupture and the proliferating cells in the fragmented tendons reflected more of the features of repair than of degeneration and necrosis. The main source of this fibrovascular tissue was the wall of the subacromial bursa. These features clearly indicated a vigorous reparative response which might play an important role in tendon reconstitution and remodelling. We therefore suggest that extensive debridement along with subtotal bursectomy, commonly practised during surgical repair of rotator cuff rupture, should be avoided. Although strong suture margins are essential for good operative results, debridement should be judicious and preserve as much as possible of the bursa and the associated fibrovascular tissue.
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Abstract
Shoulder pain has become one of the commonest clinical problems in modern North American society. The pathogenetic mechanisms vary widely, and often times, speculations about the underlying pathology have not been substantiated by investigative studies. In the past year, progress in our knowledge about shoulder pain has not been significant. We discuss the topic by dividing shoulder pain into four categories: 1) shoulder pain of local origin; 2) pain referred to the shoulder; 3) shoulder and neck pain; and 4) shoulder pain and reflex sympathetic dystrophy. It appears that a thorough history taking, an understanding of the psychosocial background of the patient, and a complete physical are equally important in the clinical evaluation of painful shoulders.
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Drzewiecki AE, Sarkar K, Wu Y, Uhthoff HK. Usefulness of a new technique for hind limb immobilization in rats for the study of tendon healing. Arch Orthop Trauma Surg 1991; 111:39-42. [PMID: 1772724 DOI: 10.1007/bf00390192] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
To study wound repair in rat Achilles tendon, we utilized a novel surgical method for immobilizing only one hind limb. In this technique, the femoral vessels were preserved while the skin, muscles, nerves and the shaft for the femur were transected. The limb was then rotated and sutured to lie on the posterolateral flank of the animal. The recovery was prompt and the procedure affected the routine growth and metabolism of the animal minimally throughout the period of experimentation. In the immobilized limb, healing of the Achilles tendon was studied after subtotal severance in the midsection. The rats were killed at intervals of 1, 2, and 4 weeks postoperatively. After 1 week, the surface of the wound was covered by a thin layer of cells. A gap persisted underneath and showed fibrovascular proliferation at the margins. In 2 weeks, the gap was completely occupied by fibrovascular tissue that was beginning to align along the long axis of the tendon. By the 4th week, remodeling had occurred and the site of the wound had almost blended with the rest of the tendon. We conclude that this new technique of hind limb immobilization causes little stress on the animal, and it can be useful for the study of tendon healing.
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Sarkar K, Taine W, Uhthoff HK. The ultrastructure of the coracoacromial ligament in patients with chronic impingement syndrome. Clin Orthop Relat Res 1990:49-54. [PMID: 2323149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In an ultrastructural study of the cells and matrix of the coracoacromial ligament (CAL) in 11 patients with impingement syndrome (IS), the cells appeared variegated, in contrast to those in normal CALs. Many showed degenerative changes such as lipid inclusions in the cytoplasms or swelling of cytoplasmic organelles, especially in the vicinity of fibrin exudate where the collagenous matrix disappeared. However, some cells had increased cytoplasmic organelles, including an elaborate Golgi apparatus, indicating enhanced synthetic activity. The matrix, instead of consisting of packed collagenous fibers of fairly uniform diameter as seen in the normal CAL, contained collagen fibers of varying diameters and microfibrils. The ultrastructural features of both the cells and the matrix were suggestive of chronic effects of strain on the ligament. In patients with chronic IS, the CAL has been implicated as the likely cause of impingement when no significant bony or articular abnormality exists. This was not substantiated by the present findings. The changes in the CAL in IS are possibly secondary, and are probably induced by alterations in soft-tissue structures of the subacromial compartment.
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Abstract
Mast cells in rat hearts were studied quantitatively during normal postnatal growth and in two types of cardiac hypertrophy. Normally, cardiac mast cell density in 11-12-day-old animals is very low, but increases markedly in the following 2-3 weeks to its highest values, with a subsequent decline toward adult values. At the peak of mast cell density, the percentage of mast cells in close proximity to capillaries is also highest. In adult animals, mast cell counts are significantly higher in the right ventricle than in the left. This relation is preserved even when the right ventricle is hypertrophic, as in rats born at simulated high altitude. Chronic hypertension and swimming have little effect on the mast cell density in rat hearts. Conspicuous changes in the mast cell density at the time of capillary proliferation seem to indicate a special role played by these cells in the formation of new vessels.
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Sarkar K, Sircar BK, Roy S, Deb BC, Biswas AB, Biswas R. Global review on ORT (oral rehydration therapy) programme with special reference to Indian scene. Indian J Public Health 1990; 34:48-53. [PMID: 2101387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
This communication is an attempt to review the status and implementation of the Oral Rehydration Therapy in the programme for Control for Diarrhoeal Diseases. The Global and the Indian situations are separately discussed, with more emphasis on the latter. Use of Home Available Fluids (HAF), Salt Sugar Solution (SSS). Commercial packets of ORS and the Government supplied packets of ORS are also assessed.
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Gupta DN, Sen D, Saha MR, Sengupta PG, Sikder SN, Ghosh S, Sarkar K, Singh NC, Sharma R. Report of an outbreak of diarrhoeal disease caused by cholera followed by rotavirus in Manipur. Indian J Public Health 1990; 34:62-5. [PMID: 2101390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
An outbreak of acute diarrhoeal disease between August and October 1985 in 3 districts of Manipur state was investigated amongst 9,29,077 population at risk. The overall attack rate and case fatality rate were 0.2% and 0.9% respectively. Hospital records revealed that 58.8% of cases occurred amongst older children above 5 years of age. V.cholera was isolated from 25.3% of cases sampled. Interestingly, increased frequency in weekly admission of cases amongst children during first two years of life increased in the beginning of October when the original peak of diarrhoeal outbreak was about to decline. The October peak was caused by rotavirus which could be detected from 50.0% of diarrhoeal children in this age group. This possibly reflected beginning of the usual rotavirus diarrhoea season in the locality.
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Uhthoff HK, Hammond DI, Sarkar K, Hooper GJ, Papoff WJ. The role of the coracoacromial ligament in the impingement syndrome. A clinical, radiological and histological study. INTERNATIONAL ORTHOPAEDICS 1988; 12:97-104. [PMID: 3410622 DOI: 10.1007/bf00266972] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Seventeen patients with a painful arc syndrome and tenderness over the coracoacromial ligament were selected to demonstrate the changes in the coracoacromial ligament in the impingement syndrome. Plain X-ray examination was normal and a preoperative subacromial bursogram demonstrated impingement in only three out of 17 patients. However, at operation the subacromial space under the coracoacromial ligament, which normally admits the tip of the little finger, appeared unusually tight and barely accessible in 15 out of 17 patients. Histological examination of the biopsied ligament showed degenerative changes but no increase in fibrous tissue. We conclude that in the absence of bony overgrowth the initial change is an increased volume of the soft tissues in the subacromial space. Consequently, the space is compromised by the swelling of its contents, which exert abnormal pressure on the overlying coracoacromial ligament and cause degenerative changes in the ligament. The symptoms of impingement appear because of the unyielding nature of the coracoacromial ligament. Subacromial bursography may not be a reliable test when the coracoacromial ligament is the site of impingement.
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Sarkar K. Mitochondrial inclusions in renal epithelial cells of magnesium-deficient rats. JOURNAL OF SUBMICROSCOPIC CYTOLOGY AND PATHOLOGY 1988; 20:179-84. [PMID: 2836050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In rats with prolonged magnesium deficiency, paracrystalline inclusions in mitochondria were found frequently in the epithelial cells of the thick ascending limb of Henle, especially in the region of the upper medulla. The inclusions presented a variegated appearance. Some were filamentous aggregates, many had alternating dark and light bands, and others were elongated rectangular densities. They were not found in tubules with calcific deposits where the cells showed degenerative changes. This suggested that the inclusions were probably due to altered cell metabolism and not products of cell degeneration.
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Rakusan K, Korecky B, Sarkar K, Turek Z. Merits and pitfalls in morphological assessment of cardiac growth. FEDERATION PROCEEDINGS 1986; 45:2580-4. [PMID: 2944767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The basic principles of quantitative morphological analysis of myocardial tissue are presented. Particular attention is paid to the effects of stimulated cardiac growth on the relationship between cell size and various indices of myocardial capillary supply in pressure-overloaded rat hearts. The importance of adequate sampling and of the number of measurements is stressed with respect to reliable estimation of the mean values but even more for assessment of variability of the measured data. When estimating myocardial capillary supply by average values of capillary density and/or of areas supplied by a single capillary, this crucial information is missing. Therefore the merits of more advanced techniques allowing for the estimation of variability of capillary spacing are critically examined and the significance of their application to myocardial tissue is outlined (method of concentric circles and method of triangular nets). Finally, the importance of variability of capillary spacing on oxygen supply is demonstrated. The variability of capillary spacing alone may affect oxygen supply independently of the average values of intercapillary distance.
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Sarkar K, Buckley C, Uhthoff HK. Liposarcoma simulating a Baker's cyst: a case study. ARCHIVES OF ORTHOPAEDIC AND TRAUMATIC SURGERY. ARCHIV FUR ORTHOPADISCHE UND UNFALL-CHIRURGIE 1986; 105:316-9. [PMID: 3778169 DOI: 10.1007/bf00449934] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We present a case of liposarcoma in a 65-year-old man in whom the tumor first appeared as a soft, cystic mass at the medial margin of the left popliteal fossa. The mass simulated a Baker's cyst. The patient remained untreated for almost 7 months from the discovery of the mass. With worsening pressure symptoms, a biopsy was done that confirmed the clinical diagnosis of liposarcoma. The leg was amputated, but the patient died 2 years later with clinical evidence of pulmonary metastasis. By presenting this case report, we stress the importance of carefully investigating for malignancy all masses presenting as a Baker's cyst in persons past middle age.
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Brunet JA, Sarkar K, Uhthoff HK. Ultrastructure of the fibrous tissue surrounding internal fixation devices. Clin Orthop Relat Res 1986:84-94. [PMID: 3720147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The possible bursal nature of the fibrous tissue that develops like a capsule over internal fixation devices was studied ultrastructurally in 13 human and four canine cases. In both species, the basic structural pattern was similar. The capsule had two distinct zones. The superficial compact zone appeared as a pseudomembrane, and consisted of elongated fibrocytes arranged transversely in a collagenous and microfilamentous matrix. In the deep zone, the cytoplasm and its constituents of connective tissue cells varied from meager to abundant. The structural organization of the capsule as well as its cellular characteristics did not conform to the specificities of an adventitious bursa. The capsular tissue did not appear to be affected by such host factors as age; implant alloy composition; the type of the underlying bone or its abnormalities; duration of implantation, or superficial or deep location of the metal device. Inflammation rarely occurred in the capsular soft tissue, including those cases where pain developed over the implants following an uneventful bone union. Because metal implants do not induce formation of adventitious bursa, pain over an uncomplicated implant is not likely to be due to a bursitis.
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Sarkar K, Kinson GA, Rowsell HC. Embryo resorption following administration of steroidal compounds to rats in mid pregnancy. CANADIAN JOURNAL OF VETERINARY RESEARCH = REVUE CANADIENNE DE RECHERCHE VETERINAIRE 1986; 50:433-7. [PMID: 3742378 PMCID: PMC1255240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In the course of experiments on the effects of anabolic steroids on the myocardium of rat conceptuses, we found that subcutaneous implantation of 10 mg of estradiol, Dianabol or testosterone to rats in mid pregnancy, resulted in embryo resorption. Placental tissue was identified only in estradiol-treated rats which also demonstrated a large amount of serosanguineous fluid that dilated the horns considerably. The yellow nodules of placental attachment sites were represented histologically by cellular and vascular proliferations between the inner and outer layers of the myometrium. The nodular aggregates of cells had variable features according to the steroid administered. Neither decidual cells nor metrial glands that are reported to be the constituents of placental attachment sites were seen in our material. We conclude that anabolic steroids are potent agents for embryo resorption, and that the cells in the nodules of placental attachment sites are likely to be derived from the myometrium.
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Narbaitz R, Marino I, Sarkar K. Lead-induced early lesions in the brain of the chick embryo. TERATOLOGY 1985; 32:389-96. [PMID: 4082070 DOI: 10.1002/tera.1420320309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A single dose consisting of a solution of lead nitrate containing 1 mg lead in 0.1 ml distilled water was injected into the air chamber of chicken eggs on the tenth day of incubation. The injected embryos were killed 24, 48, or 72 hours after the injection. Control embryos were injected with a similar volume of distilled water or of an equimolar calcium nitrate solution on the tenth day and killed 72 hours after. Portions of the optic lobes were processed for their electron microscopic study. Multiple hemorrhagic foci appeared 24 hours after the administration of lead. Red blood cells were found to exit the blood vessels through the spaces between otherwise normal-looking endothelial cells; tight junctions were always found blocking the interendothelial spaces except during the migration of red blood cells through them. Vacuolization of the cytoplasm and mitochondrial swelling and disorganization were observed in the endothelial cells only during the third day after the injection. Similarly, histological and ultrastructural alterations of nerve cells were only found on the third day after the treatment. Hemorrhagic foci were never found in control embryos. Our observations are consistent with the idea that the hemorrhages constitute the primary lesion produced by lead. They also suggest that the hemorrhages are not the result of rupture of previously altered endothelial walls but occur by diapedesis through the interendothelial clefts.
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Sarkar K, Nash LA, Levine DZ. Effects of ureteral ligation on renal medullary lesions of potassium depletion. BRITISH JOURNAL OF EXPERIMENTAL PATHOLOGY 1983; 64:677-83. [PMID: 6318793 PMCID: PMC2040826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In diet-induced potassium depleted rats, tissue potassium content of the renal medulla decreases and membrane-bound droplets form in the cytoplasm of medullary cells. To elucidate the interrelationship between medullary potassium concentration and intracytoplasmic droplets, ligation of the left ureter was performed on rats deprived of potassium for 2 weeks. Our results show that, even in the absence of supplemental potassium provision to the animal, a unilateral rise in tissue potassium of the ligated left kidney was significant. After 4 days of ligation, the left medullary potassium was 41.96 +/- 0.79 mEq/100 g dry weight compared to 32.51 +/- 0.84 mEq/100 g dry weight (P less than 0.001) of medullary potassium in the non-ligated right kidney. The rise in tissue potassium in the left kidney coincided with the dissolution of intracytoplasmic droplets. We conclude, that mechanical obstruction to urinary flow can dissolve storage droplets in medullary cells and that the lysis of droplets is made possible by the increase in medullary tissue potassium content.
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Narbaitz R, Sarkar K, Fragiskos B. Differentiation of bones and skeletal muscles in chick embryos cultured on albumen. REVUE CANADIENNE DE BIOLOGIE EXPERIMENTALE 1983; 42:271-7. [PMID: 6686885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Chick embryos were cultured in hemispheric dishes containing 25 ml fresh albumen. The addition of albumen, known to the relatively poor in free calcium, increased the deficit of calcium regularly observed in embryos cultured with other methods. In spite of this, the embryos survived and differentiated adequately for prolonged periods of time. Most of the cultured embryos presented malformations of the long bones of the limbs consisting of bowing and exuberant growth of bone trabeculae in the concavity of the bend. Block staining with alizarin showed that bones were undermineralized at the time in which bending occurred. Leg muscles differentiated adequately as judged from their electron microscopical observation. It is concluded that the malformations result from the action of normal muscles on undermineralized bones. The growth of bone trabeculae at the concavity of the bend probably results from the piezoelectrical stimulus produced by the bending of the bones. The concentrations of both the ionized and bound fractions of blood calcium were significantly reduced in the cultures. The system appears to constitute an adequate model for further explorations on the effects of prolonged hypocalcemia on the differentiation of different tissues and organs.
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