T Donáth

United Arab Emirates University, Al Ain, Abu Dhabi, United Arab Emirates

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Publications (24)23.58 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The morphological and biochemical changes that occur in the early phase of streptozotocin (STZ)-induced beta cell failure have not been characterized. The pancreas and plasma of rats treated with STZ were processed for morphological and biochemical parameters 1-24 h and 4 weeks after STZ treatment. Marked reduction in body weight was observed as early as 3 h post STZ treatment and hyperglycemia coupled with hypoinsulinaemia appeared in rats 1 h after treatment with STZ. Hyperglycemia, hyperglucagonemia and hypoinsulinemia became permanent 24 h after STZ treatment. The number of insulin-positive cells decreased significantly (p<0.05) at 24 h after STZ treatment with a concomitant increase in the number of glucagon-immunoreactive cells. Electron microscopy showed coalescing of beta cell granules 18 h after STZ treatment. A near to complete degranulation of beta cells settled at 21 h after STZ administration. The pancreatic tissue and plasma levels of adrenaline and noradrenaline increased significantly (p<0.004: pancreatic tissue; p<0.04: plasma) 3 h after STZ treatment and remained high after a reduction at 6 h post STZ treatment. The pancreatic tissue and plasma levels of 5-HIAA decreased significantly (p<0.002 pancreatic tissue; p<0.04: plasma) 1 h after STZ treatment and remained low after a reduction at 6-9 h post STZ treatment. STZ elicited significant dose-dependent increases in insulin secretion from the isolated pancreas. The early changes in catecholamine level may be used in screening and follow-up studies on diabetes mellitus.
    Experimental and Clinical Endocrinology & Diabetes 05/2010; 118(10):699-707. · 1.76 Impact Factor
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    ABSTRACT: The present study was designed to compare the morphological changes occurring in pancreatic tissue fragments transplanted into the anterior eye chamber (AEC) and the subcutaneous (SC) regions of the rat. Pancreatic tissue segments were removed from the tail end of the pancreas of neonatal rats and transplanted into the AEC and SC region of the neck of homologous rats. Five weeks after transplantation, the grafts were removed and processed for light microscopy, immunohistochemistry and radioimmunoassay. In both pancreatic tissue grafts, the acinar cells degenerated completely after transplantation. In contrast to this, insulin-, glucagon-, somatostatin- and pancreatic polypeptide-positive cells and pancreatic ducts survived equally well in both the AEC and SC grafts. The pattern and percentage distribution of insulin-, glucagon-, somatostatin- and PP-producing cells in the AEC and SC grafts was similar to that observed in normal pancreas. However, the percentage distribution of glucagon- and PP-containing cells was significantly (p < 0.03) lower in SC grafts when compared to normal. Radioimmunoassay showed that the AEC and SC pancreatic tissue grafts contained large quantities of insulin and glucagon. However, the insulin content of AEC was slightly but not significantly higher than that of SC grafts. The protein content of pancreatic tissue grafts in these transplantation sites was still significantly (p < 0.05) lower compared to normal. Lymphatic infiltration was also more conspicuous in SC grafts compared to AEC grafts. This infiltration by lymphatic cells was confined only to the endocrine portion of the graft. In conclusion, pancreatic tissue grafts survived in both the AEC and SC regions of rats but the AEC appears to be more conducive to graft survival than the SC region.
    European Journal of Morphology 01/2002; 39(5):257-68.
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    ABSTRACT: The aim of this study was to examine the disease characteristics and complications of diabetes mellitus in patients in a Hungarian rural community. Data relating to age, sex, date of onset of diabetes, fasting blood glucose values and all diseases associated with diabetics were retrieved from the medical records of patients. Almost six percent (5.7%) of the population has diabetes mellitus. The percentage of Type I diabetic patients in this population was 5.8 percent. The prevalence of diabetes was slightly but not significantly higher in females than in males. The mean age of the diabetic population was 52.1 +/- 11.3 for male and 53.47 +/- 15.7 for the female patients. The peak age of onset of diabetes mellitus was in the sixth decade of life. The mean fasting blood sugar value was 10.64 +/- 0.6 and 10.57 +/- 0.5 mmol L(-1), in male and female diabetic patients (n = 103), respectively. Diabetic patients presented with many signs and symptoms in the general practice setting. The findings of this study showed that diabetics present with many disease conditions and signs and symptoms in the general practice setting. Many of these conditions are known to be associated with diabetes while others are not. As a result of the adverse effects of diabetes mellitus on the cardiovascular system and on body metabolism as a whole, the damage and morbidity caused by diabetes mellitus may have been underestimated. The results of this study have shed light on the unrecognised complications of diabetes mellitus.
    Archives of Physiology and Biochemistry 08/2001; 109(3):281-91.
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    ABSTRACT: Vasoactive intestinal polypeptide (VIP) is an inhibitory non-adrenergic, non-cholinergic transmitter, which mediate in the relaxation of sphincters of the gastrointestinal tract. The aim of this study was to determine whether there is a change in the pattern of innervation and tissue content of VIP in the rat gastroduodenum after the onset of streptozotocin (STZ)-induced diabetes mellitus. Diabetes was induced by a single intraperitoneal injection of STZ (60 mg Kg(-1)). Four weeks after the induction of diabetes mellitus, the rats were anaethetised and the pancreata were removed for further processing. VIP was localized and measured in normal and diabetic rat gastroduodenal tissues by immunohistochemistry and radioimmunoassay, respectively. VIP immunoreactivity was stronger in the ganglion cells of the submucosal and myenteric plexuses of the gastric antrum and duodenum of normal rats (n = 6) when compared to that of diabetic rats (n = 6). Moreover, the number of VIP-positive neurons was significantly lower in the gastrointestinal tract of diabetic rats compared to normal. The VIP content of the gastric antrum and duodenum of diabetic rat was significantly lower (p< 0.05) than that of normal rat. In contrast to the lower tissue levels of VIP in the gastroduodenal segment of diabetic rats, the plasma level of VIP was significantly higher (p< 0.04) in diabetic rat compared to normal. The plasma level of VIP in normal rats was comparable to that measured in normal human beings. A low tissue level of VIP in the gastroduodenal tract of diabetic rat may contribute in part to the abnormal gut motility observed in diabetic patients.
    Archives of Physiology and Biochemistry 07/2001; 109(3):246-51.
  • E Adeghate, T Donáth
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    ABSTRACT: Intrinsic nerves play a crucial role in the regulation of body functions. It is therefore of paramount importance to be able to study the biology of intrinsic nerves in tissue grafts. The anterior eye chamber of rats has long been used to study different biological mechanisms, growth and differentiation of a variety of tissues, because of the transparency of the cornea, which also allows macroscopic changes to be seen. Despite its extended use, a detailed, easy to follow description of the technique of tissue and cell transplantation into the anterior eye chamber has not been presented. In this study, pancreatic tissue fragments were transplanted into the anterior eye chamber of rats alone or with brain tissue fragments to examine the survival and viability of intrinsic nerves in these tissue fragments, which have been detached from their original extrinsic nerves. The pancreatic transplants contained intact 5-HT and AChE-positive intrinsic neurons. The brain tissue grafts contained many AChE-enzyme reactive cells. The method is simple and can be used to study the morphology or physiology of intrinsic neurons in any tissue fragment. The grafts are easily vascularised and reinnervated because of the rich blood and nerve supply of the iris which forms the bed of the anterior eye chamber. The graft will also survive with ease because the anterior eye chamber is an immunologically privileged site. In conclusion, the intrinsic nerves of pancreatic and brain tissue fragments can survive after several weeks of transplantation into the anterior eye chamber of rats. In addition to this, these intrinsic nerves have the ability to produce and or store neurotransmitters and their enzymes.
    Brain Research Protocols 12/2000; 6(1-2):33-9. · 1.82 Impact Factor
  • Transplantation Proceedings 03/1998; 30(2):567-8. · 0.95 Impact Factor
  • Transplantation Proceedings 03/1998; 30(2):592. · 0.95 Impact Factor
  • E Adeghate, T Donáth
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    ABSTRACT: The administration of exogenous insulin ameliorated the symptoms and increased the life expectancy of insulin dependent diabetic patients, but could not cure or prevent the devastating complications including retinopathy, nephropathy and angiopathy. It was recognised that despite insulin therapy, the severity and frequency of the degenerative late complications are still high in patients suffering from diabetes mellitus. The recognition of the increased frequency of and complications accompanying the disease has intensified efforts by scientists to find the form of pancreatic tissue to be transplanted and the suitable site in a bid to secure an insulin producing graft. This review presents an update in pancreatic organ and fragment transplantation. The history of the pancreas is also brought into limelight to show the long, hard and exciting path pancreas and diabetes mellitus have both gone through. An account is also given of experimental and clinical pancreatic whole organ/fragment transplantation including transplantation sites, the evaluation of the viability of pancreatic grafts and the complications of transplantation. Pancreatic islet transplantation is not discussed.
    Acta chirurgica Hungarica 02/1998; 37(1-2):133-51.
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    ABSTRACT: To determine an in vitro marker of viability during pancreatic preservation, 12 pigs underwent total pancreas harvesting, and graft were stored in Euro-Collins or Belzer perfusion solution for up to 24 hours. Amylase concentration of the storage solution was analyzed in regular periods and tissue samples were taken for acridine-orange histochemical evaluation of viability in the same time. In vitro pancreatic amylase release (IU/g pancreas tissue) was calculated from the volume of solution and the weight of graft. A significant increase of amylase release was found in the course of preservation in both media. Comparing amylase release in different solutions we found significant difference between Euro-Collins and Belzer media (4 hours: 6.45 IU/g vs. 2.2 IU/g, 8 hours: 11.5 vs. 3.58, 24 hours: 8.7 vs. 42.8, respectively). Comparison of amylase release with histochemical evaluation of viability showed strict correlation. We concluded that amylase release is a good marker for exocrine tissue destruction as well as viability of preserved pancreas. Our data confirms that Belzer solution is superior in pancreatic preservation. It is suggested that after adaptation into human model in vitro pancreatic amylase release could be a time- and cost-saving, useful method in predicting pancreatic transplant function prior graft implantation.
    Acta chirurgica Hungarica 02/1997; 36(1-4):46-8.
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    ABSTRACT: This study demonstrates the presence and distribution of atrial natriuretic peptide (ANP) pancreastatin (PST), leucineenkephalin (Leu-ENK), galanin (GAL), and insulin in the pig pancreas. The effects of PST, ANP, Leu-ENK, and GAL on protein and amylase secretion were also investigated to determine their functional role in the control of pancreatic secretion. PST-immunoreactive cells were observed in the islet of Langerhans and in the wall of the ducts. Leu-ENK-immunopositive cells were observed in both the endo-and exocrine pancreas. It is colocalized with insulin in the islet of Langerhans. ANP immunoreactivity was discernible in nerve fibers and cells of the exocrine pancreas. GAL-immunopositive cells were observed in close association with insulin-positive cells in the islets of Langerhans and in the exocrine pancreas. Stimulation of isolated pancreatic segments with either ANP or Leu-ENK resulted in increased protein secretion and amylase output. The Leu-ENK-evoked amylase secretion was antagonized by naloxone. Pancreastatin was effective at all concentrations, but low concentration had more marked secretory effects whereas GAL failed to evoke any significant increases in either protein or amylase secretion. The results of the study have demonstrated a close association of peptidergic fibers with the secretory cells of the pancreas. The nerve fibers can release peptides that in turn can stimulate protein and amylase secretion.
    Peptides 02/1996; 17(3):503-9. · 2.61 Impact Factor
  • Advances in Experimental Medicine and Biology 02/1994; 350:57-60. · 2.01 Impact Factor
  • E Adeghate, T Donáth
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    ABSTRACT: The distribution of acetylcholinesterase (AChE) at the ultrastructural level was investigated in normal and in pancreatic fragments transplanted for 56 days into the anterior eye chamber of heterologous rats using enzyme cytochemical methods. Acetylcholinesterase reaction products were seen on the basal surface of the acinar cells in normal pancreas. Acetylcholinesterase enzyme activity was also detected on the axolemma of the surviving nerve fibres. This enzyme reaction product forms alternating thick and thin bands on the axolemma. Some of these AChE-positive nerve fibres accompany blood vessels that also survive after transplantation. AChE were seen in cytoplasm adjacent to the surviving alpha and pancreatic polypeptide cells. We conclude that the ability of some neurons and cells to produce and or store acetylcholinesterase is still retained after transplantation of pancreatic tissue into the anterior eye chamber of rats.
    Cell Transplantation 01/1994; 3(2):171-7. · 3.57 Impact Factor
  • Ernest Adeghate, Tibor Donáth
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    ABSTRACT: Dopamine-beta-hydroxylase(DBH)-positive nerves were demonstrated in normal and in pancreatic tissue fragments transplanted for 22 and 32 days into the anterior eye-chamber of rats using immunohistochemical techniques. Dopamine-beta-hydroxylase-immunopositive neurons of different shapes could be observed in normal pancreas. The neurons had either spindle or oval shapes. In the transplanted tissue, DBH-positive neuronal profiles were found in the stroma. In some cases DBH-immunopositive cells appeared as a cluster of cells around pancreatic ducts and blood vessels or as solitary cells. The wall of pancreatic ducts in the transplants also contained DBH-immunopositive nerve profiles.
    Journal of Chemical Neuroanatomy 05/1991; 4(3):223-7. · 2.52 Impact Factor
  • E Adeghate, T Donáth
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    ABSTRACT: The endocrine cells of embryonic pancreatic tissue fragments transplanted into the anterior eye-chamber of rats for 74 days were investigated immunohistochemically and morphometrically and the results obtained were compared with that of normal tissue. Four types of endocrine cells were identified and their distribution was as follows: insulin: 42-52%, glucagon: 11-28%, somatostatin: 4%, and pancreatic polypeptide-positive cells: 3-6%. Their size in square micrometer were as follows: 153, 110, 38 and 51. The area, number, distribution and topography of these endocrine cells with regard to each other did not differ significantly from that of normal tissue. The area of each islet and their cell population vary considerably both in normal and transplanted pancreas.
    Experimental and clinical endocrinology 02/1991; 98(3):193-9.
  • Ernest Adeghate, Tibor Donáth
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    ABSTRACT: Neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) immunoreactive nerves were demonstrated in 21-day-old embryonic pancreatic tissue fragments transplanted into the anterior eye chamber of rats for 22, 45 and 109 days and in 60-day-old normal adult pancreas using immunohistochemical technique. In normal adult tissue, NPY-positive neurons lie close to the basal and lateral walls of the acinar cells. NPY-containing nerve fiber plexuses were found around blood vessels. VIP-immunopositive nerves were also discernible in the outer parts of the islets of Langerhans and on pancreatic ducts. In the transplants, it is not only the neural elements that survived but also the pancreatic ducts and the endocrine cells. VIP- and NPY-positive neurons were found in the stroma of the surviving pancreatic tissue. The distribution of these neural elements is similar to that of normal tissue in the surviving pancreatic ducts but different with regards to the acinar tissue. This study confirms that intrinsic nerves can survive and synthesize polypeptides even after 109 days of transplantation into the anterior eye chamber.
    Peptides 11/1990; 11(6):1087-92. · 2.61 Impact Factor
  • E Adeghate, T Donáth
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    ABSTRACT: Morphological changes in 21-day-old embryonic and 2-day-old postnatal rat pancreatic tissue fragments transplanted into the anterior eye chamber of homologous animals for 74, 77, 180, and 534 days were investigated using light and electron microscopic, acetylcholinesterase enzyme, and immunohistochemical methods. The pancreatic acinar cells degenerated and were not observed at this stage of transplantation. The ductal system proliferated and partly differentiated into endocrine cells that subsequently formed many new islets of Langerhans as well. The structures of beta-, alpha-, delta-, and pancreatic polypeptide cells were found to be intact even 1.5 years after transplantation. In addition to this, the organization of these cells inside the islets is similar to that of normal pancreatic tissue. The transplanted tissue fragments were well vascularized with blood vessels and innervated also by serotonergic cells and acetylcholinesterase-positive neurons. It is concluded that pancreatic tissue fragments, with the exception of the acinar component, can grow and survive with intact structure in the anterior eye chamber of homologous rats for up to 1.5 years.
    Pancreas 06/1990; 5(3):298-305. · 3.01 Impact Factor
  • T Donáth
    Acta morphologica Hungarica 02/1990; 38(3-4):155-8.
  • Ernest Adeghate, Tibor Donáth
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    ABSTRACT: Acetylcholinesterase-and monoamine oxidase-positive neuronal elements were investigated in embryonic pancreatic tissue fragments transplanted into the anterior eye-chamber of rats for 28, 77, and 135 d, using enzyme histochemical method. Amongst the components of the parenchymal tissue, only the ductal and islets cells survived. Monoamine oxidase (MAO)- and acetylcholinesterase (AChE)-positive neuronal cell bodies and fibres were found to be considerably many in the surviving and newly formed islets of Langerhans, in the wall and periphery of the tubules. Their topography with regards to these components is similar to that in normal tissue. In normal tissue, MAO-positive fibers abut the basal and lateral parts of acinar cells. AChE-positive neurons are most conspicuous in the islets and in the wall of pancreatic ducts.
    Acta Histochemica 02/1990; 89(2):183-6. · 1.76 Impact Factor
  • T Donáth, E Adeghate
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    ABSTRACT: The ultrastructure of pancreatic light and clear endocrine cells in normal and transplanted tissue fragments in the anterior eye-chamber of rats was described by electron microscopy. Compared to the dark cells, the light cells contain a conspicuously poorly stained cytoplasmic ground substance with varying number of rough endoplasmic reticulum cisterns and secretory granules. The quantities of these two organelles are inversely proportional to each other. "Light" alpha, beta, delta and pancreatic polypeptide cell-types were identified in normal and transplanted tissue. Out of these, the light alpha cell is the most commonly occurring. The "clear" endocrine cells are much fewer in number than the light cells. They contain well stained cytoplasm with numerous low electron density vesicles and few secretory granules. There is no ultrastructural difference between the light and clear cells in normal and in transplanted tissue for 77 and 534 days. The occurrence of light and clear cells in the transplanted tissue shows that these transplants behave morphologically like normal tissue. These cell types might be related to the different stages of secretory granule synthesis and maturation.
    Acta morphologica Hungarica 02/1990; 38(3-4):217-24.
  • E Adeghate, T Donáth
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    ABSTRACT: The mechanism of secretory granule formation and exocytosis in the endocrine cells of normal and transplanted rat pancreas was studied using electron microscopy. On the one hand, formation of secretory granules starts with the dilatation of the 2 ends or the vesicularization of the middle parts of rough endoplasmatic reticulum (RER). On the other hand, prohormone ribosomes condense into the vesicles of the GOLGI apparatus. This probably indicates that the GOLGI complex is not the only source of formation of secretory granules. Exocytosis occurs with the formation of an electron dense streak between the perigranular membrane and the apical cell membrane. This is followed by the rupture of the streak at this midpoint allowing the granule to extrude into the space between the cell membrane and the parenchymal basal membrane. This fusion-rupture-extrusion mechanism repeats itself at the parenchymal and capillary basal membranes and also at the endothelium until it gets into the capillary lumen, showing that hormones of pancreatic endocrine cells may be actively transported into circulation as intact secretory granules. There is no significant morphological difference between the mechanism of secretory granule formation in normal and transplanted pancreatic tissue.
    Gegenbaurs morphologisches Jahrbuch 02/1989; 135(5):697-704.

Publication Stats

112 Citations
23.58 Total Impact Points

Institutions

  • 1998–2010
    • United Arab Emirates University
      Al Ain, Abu Dhabi, United Arab Emirates
  • 1988–2000
    • Semmelweis University
      • • Department of Anatomy, Histology and Embryology
      • • First Department of Internal Medicine
      Budapeŝto, Budapest, Hungary
  • 1997–1998
    • Uzsoki Hospital
      Budapeŝto, Budapest, Hungary