Search PubMed⌕ Search

Biomedical subjects

E Tamm

Publications and source records attributed to E Tamm.

27 records · Page 2Linked to original sources
PubMed1990

Visualization of hyaluronic acid in the anterior segment of rabbit and monkey eyes.

Hyaluronic acid was visualized using a new histochemical technique: the hyaluronic acid-binding region of the cartilage proteoglycan was isolated, linked with biotin and used in histological sections as a ligand for hyaluronic acid. Staining was performed using the avidin-biotin-peroxidase technique. The presence of hyaluronic acid in the anterior segments of rabbit and monkey eyes was studied in fresh-frozen, as well as in fixed paraffin sections; addition of cetyl-pyridinium chloride to the fixative was essential. In both species intense staining was seen in the stroma of the conjunctiva, the connective tissue of the ciliary processes, and on the apical membranes of the corneal endothelium. Species differences were observed in both conventional and unconventional outflow pathways. In rabbits, the tissue located directly adjacent to the aqueous plexus and the connective tissue surrounding the poorly developed ciliary muscle were stained. In monkeys, only the anterior, non-filtering part of the trabecular meshwork and the outer wall of Schlemm's canal showed intense staining in paraffin sections. In frozen sections, the inner wall (cribriform region of the trabecular meshwork) was also stained. The spaces between the anterior part of the ciliary muscle bundles remained almost unstained.

Animals↗
PubMed1990

[Electron microscopy and immunohistochemical studies of the intraocular pressure lowering effect of prostaglandin F2 alpha].

Topically applied prostaglandin F2 alpha (PGF2 alpha) has been shown to lower intraocular pressure in cynomolgus monkeys. In this study the morphological changes following topical treatment of seven cynomolgus monkeys with 4 micrograms PGF2 alpha isopropylester for 5-8 days were investigated and compared with the eyes of five normal animals. Quantitative light microscopical, ultrastructural and immunhistochemical methods were used. No cellular signs of inflammation were seen in any of the eyes. Slight edema in the most anterior part of the ciliary processes occurred in most eyes, but only in parts of the circumference. The most pronounced change was dilation of the intramuscular spaces within the ciliary muscle. No changes were observed in the extracellular matrix within the muscle bundles, which consist partly of type IV and VI collagen, laminin and fibronectin. In the connective tissue between the muscle bundles, loss of collagen type I and III fibrils was observed. Additionally, macrophages were found with phagolysosomes containing phagocytized collagen fibrils. We suggest that loss of extracellular material leads to a widening of the uveoscleral outflow pathways of ciliary muscle and thereby to a reduction in intraocular pressure.

Animals↗
PubMed1990

Membrane voltage recordings in a cell line derived from human ciliary muscle.

A smooth muscle cell line (H7CM) was established from the ciliary muscle of a 1-day-old human infant. The cultured cells had a normal female karyotype (46 XX) and could be maintained in cell culture for at least 11 generations. A common feature of confluent cultures was the presence of abundant bundles of 6-7 nm microfilaments associated with dense bodies. Both the ultrastructural appearance and the presence of smooth muscle-specific alpha-isoactin (also present in the human ciliary muscle in situ) support the smooth muscle origin of the H7CM cell line. Continuous membrane voltage (Vm) recordings were obtained in confluent monolayers of H7CM cells using glass microelectrodes. Resting Vm in 105 impalements averaged -66.2 +/- 0.7 mV (mean +/- standard error of the mean). In this system, rapid membrane transients induced by changing of the superfusing test solutions were detectable. Relative K+ conductance was characterized, and the contribution of electrogenic sodium/potassium adenosine triphosphatase to Vm was investigated. Under control conditions, H7CM cells were electrically quiescent. However, action potentials could be induced by application of 10 mM barium. Barium-induced action potentials were not abolished by removal of extracellular Na+ nor were they inhibited by the presence of tetrodotoxin. However, they were blocked by verapamil, fulfilling criteria believed to be typical for smooth muscle cells. Acetylcholine, carbachol, and to a lesser extent pilocarpine induced a reversible Vm depolarization. The effect of acetylcholine was blocked by atropine, implying muscarinic receptor involvement in the Vm response. Collectively, these findings show the potential usefulness of cultured ciliary muscle cells in understanding further the cellular mechanisms underlying drug-induced contraction of the human ciliary muscle.

Acetylcholine↗
PubMed1989

The effects of ocular hypotensive doses of PGF2 alpha-isopropylester on anterior segment morphology.

In cynomolgus monkeys, PGF2 alpha when topically applied in the isopropylester form in doses sufficient to reduce IOP, has much less effect on the ciliary epithelium than PGs have previously been reported to cause in rabbits. We observed no accumulation of wandering cells (leukocytes and histiocytes), which are one of the typical signs of inflammation. The changes noted in the ciliary epithelium itself were mild, which may either be a sign of mild inflammation or might be caused by the greatly reduced IOP and consequent alteration in internal pressure relationship. The functionally important morphological effect of PGF2 alpha seems to be a widening of the uveoscleral pathways within the ciliary muscle, which seems primarily to be a result of relaxation of the muscle fibers and secondary to loss or modification of extracellular material. Preliminary studies indicate that both of these morphological alterations are at least partly reversed within 12 hours after the last PG treatment. This is consistent with the concept that the observed morphological changes in the ciliary muscle are associated with the ocular hypotensive effects of PGF2 alpha since such hypotensive effects are usually maintained for less than 12 hours after the topical application of this drug. Our findings suggest that PGF2 alpha-IE and possible other PGs, may provide a useful new tool to reduce IOP and to explore the physiological and pharmacological mechanisms that are involved in the control of uveoscleral outflow.

Animals↗
PubMed1988

Age-related loss of morphologic responses to pilocarpine in rhesus monkey ciliary muscle.

Ciliary muscle topography and connective tissue distribution were studied by light microscopy in atropinized, pilocarpinized, or untreated eyes from rhesus monkeys of various ages. With age, the connective tissue ground plate between ciliary muscle and ciliary processes thickens, while there is very little increase in connective tissue within the ciliary muscle. With age, the atropinized muscle becomes shorter and smaller in area while it remains unchanged in width and position. In pilocarpinized eyes, the ciliary muscle is shorter, narrower, smaller in longitudinal and total area (ie, more circular and compact), and positioned more anteriorly than in contralateral atropinized eyes. These contractile responses to pilocarpine diminish with age at a rate similar to that for accommodative decline. According to these topographic findings, physicians seeking the pathophysiologic characteristics of presbyopia, which occurs in humans and rhesus monkeys on a comparable relative time scale, should redirect their attention toward the ciliary muscle.

Administration, Topical↗
PubMed1988

Morphological study of the anterior segment of cynomolgus monkey eyes following treatment with prostaglandin F2 alpha.

Topically applied prostaglandin F2 alpha has been shown to lower intraocular pressure in cynomolgus monkeys. In this study the morphological changes, following topical treatment with 4-50 micrograms of prostaglandin F2 alpha for 4-8 days, were investigated. Semiquantitation of (1) accumulation of white blood cells as one sign of inflammation, (2) edema and (3) enlarged spaces between ciliary muscle cells were performed. Eighty sections per eye encompassing the whole circumference were investigated. No accumulation of white blood cells was seen in any of the eyes. Slight edema in the most anterior part of the ciliary processes occurred in most eyes, but only in part of the circumference. These changes could be either directly induced by the prostaglandin treatment or secondary to the decrease in intraocular pressure. The most pronounced change was the dilatation of the intramuscular spaces. These enlarged spaces could explain the physiologically shown increase in uveoscleral outflow.

Animals↗
PubMed1988

Age changes in rhesus monkey ciliary muscle: light and electron microscopy.

The ciliary muscle from 44 rhesus monkeys ranging in age from 137-day fetuses and a 3-week neonate to 35-year-old adults was studied by light and electron microscopy. In the fetuses and the neonate, the muscle cells appeared immature, and the muscle consisted mainly of longitudinally oriented fibers. By age 1 year, the muscle fibers were aggregated into bundles, and within each bundle the individual fibers were packed tightly together. In sagittal section, the muscle now exhibited longitudinal, reticular and circular portions. The individual muscle cells exhibited ultrastructural characteristics which set them apart from other smooth muscle cells. Age-related structural changes occurred in the ciliary muscle and intramuscular nerves, beginning at 6 years. These included increasing numbers of lysosomes, 'fingerprints', and the appearance of myelin figures within some nerve endings and nerve fibers. These alterations became more frequent and pronounced with age, and in elderly animals were seen in all regions of the muscle and around its entire circumference. Additionally, the elderly animals exhibited overt degeneration of some muscle cells and some myelinated nerve fibers. The time-course of these age-related structural neuromuscular alterations parallels the decline of functional accommodative amplitude (i.e. presbyopia) and of the ciliary muscle's configurational response to peripheral pharmacologic and central electrical stimulation. This suggests a pathophysiologic, albeit (given the relatively moderate overall abnormalities) not necessarily causal, relationship. An age-related increase in the number of pigmented cells between the ciliary muscle bundles also occurred, with the anterior longitudinal region being affected last. This might reflect an age-related decline in uveoscleral drainage of aqueous humor.

Aging↗
PubMedDate not supplied

Pancreatic cancer: current concepts in imaging for diagnosis and staging.

Because of its late clinical presentation, pancreatic cancer remains the fourth most common cause of cancer death. Surgery is the only option for cure, and advancements in surgical technique and neoadjuvant therapy have the potential to increase the number of patients who could undergo surgery for potential cure. Accurate diagnosis and staging of pancreatic ductal carcinoma are therefore of great importance. This paper reviews the state of the art for such diagnostic modalities as computed tomography, magnetic resonance imaging, endoscopic ultrasound, positron emission tomography, and laparoscopic surgery and laparoscopic ultrasound for diagnosis and staging of pancreatic cancer. Currently, accurate diagnosis and staging probably require the use of a combination of techniques, including multiphase helical or multidetector computed tomography and/or dynamically enhanced magnetic resonance imaging with endoscopic ultrasound with fine-needle aspiration. The role of positron emission tomography still needs to be determined. The role of laparoscopic surgery and laparoscopic ultrasound may be limited in those institutions with state-of-the-art imaging techniques.

Diagnosis, Differential↗