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P Seifert

Publications and source records attributed to P Seifert.

At least 19 recordsLinked to original sources
PubMed1994

Demonstration of nerve fibers in human accessory lacrimal glands.

To provide morphologic evidence for the innervation of accessory lacrimal glands, glands were biopsied and examined using standard transmission electron microscopic techniques. Non-myelinated nerve fibers were found in the connective tissue between the glandular epithelia where they made contact with glandular epithelial cells, myoepithelial cells, vascular endothelial cells, plasma cells and fibroblasts. The distances measured between axons and target cells ranged from 30 to 130 nm. Where nerve fibers approached cells sustaining a basement membrane, their basement membranes fused to form a discrete unit resembling so-called 'synapses à distance'. Cells with no basement membrane were situated in direct contact with the basement membrane of a nerve fiber. Single axons were identified between glandular epithelial cells and cells of intralobular ducts. Most of these axons contained many small clear vesicles and a few large, dense core vesicles, a finding considered typical of cholinergic parasympathetic nerve fibers. In addition, one of the axons identified contained small dense core vesicles typical of sympathetic nerve fibers. Human accessory lacrimal glands are therefore definitely innervated, with parasympathetic structures morphologically prevailing over sympathetic structures.

Axons↗
PubMed1993

Enameloid formation in two tetraodontiform fish species with high and low fluoride contents in enameloid.

Forming teeth of parrotfish and pufferfish were viewed by transmission electron microscopy to correlate cytological features of the enameloid organ with the species' fluoride (F) content in mature enameloid. Secretory-stage inner dental epithelial cells (IDE) of parrotfish (high F) and pufferfish (low F) secreted procollagen granules into the enameloid collagen matrix. The odontoblasts of both species, less numerous than IDE cells, also contained procollagen granules at the enameloid matrix formation stage. After the full thickness of enameloid matrix collagen had been deposited, enameloid crystallites formed parallel to the long axis of the enameloid collagen fibres. Concurrently, the plasma membranes of the outer dental epithelial cells (ODE) became invaginated in both species, but to a much greater extent in parrotfish. Highly undulating parrotfish ODE cells surrounded numerous fenestrated capillaries. In contrast, pufferfish ODE cells remained straight with few adjacent capillaries. Extensive tight junctions formed between ODE and IDE cells of both species, sealing the extracellular space. With increased mineralization, enameloid collagen fibres were no longer discernible. A thin layer of amorphous material, which subsequently mineralized, was secreted on to the enameloid surface by IDE cells in both species. Pufferfish odontoblasts secreted a mineralizing amorphous layer on the pulpal aspect of the enameloid. The results suggest that at the mineralization stage, a triad of cytostructural features, highly invaginated ODE cells, highly vascularized ODE cells, and extensive tight junctions are strongly correlated with high fluoride content of mature enameloid mineral. Species without any one of these features have lower fluoride in the enameloid.

Animals↗
PubMed1993

The architecture of human accessory lacrimal glands.

Human accessory lacrimal glands were examined both light and electron microscopically and their gross architecture was reconstructed from serial sections. Every accessory lacrimal gland nodule is an individual organ with its own connective tissue coat and excretory duct. Within the gland proper, the excretory duct ramifies to form intralobular ducts, which are connected to the secretory glandular epithelia. The secretory epithelia are composed of elongated tubules terminating in short end pieces with lumina of variable width. True acini are absent. Thus, the accessory lacrimal glands are tubular glands. The cells of tubules and end pieces contain large secretory granules suggestive of a regulated mechanism of secretion. The content of organelles and the amount of secretory material present in neighboring cells can show pronounced differences. Both end pieces and tubules and, to a lesser extent, the intralobular ducts are surrounded by myoepithelial cells. The interstitial connective tissue contains blood vessels, free cells, and fibroblasts. Axons of nonmyelinated nerve fibers are in close spatial contact to vascular endothelial cells, connective tissue cells, free cells, and glandular epithelial cells. A few axons with parasympathetic characteristics and, less frequently, with sympathetic characteristics were identified between the epithelial cells of both secretory epithelium and intralobular ducts.

Blepharoptosis↗
PubMed1991

Serum fluoride level and fluoride content of enameloid.

We investigated diverse groups of fish species to determine whether the fluorine (F) contents of the dental hard tissues were related to baseline serum F levels. Serum samples, enameloid, dentin, ganoid/enamel, and bone were analyzed for F by either electron microprobe or wet chemistry. Species were categorized into two groups based on the F content of the enameloid. One group contained greater than 2.6 wt% F in enameloid, whereas the other group had less than 0.45 wt% F in enameloid. The dentin and bone from all species (or, in skates, the cartilage), as well as the ganoid/enamel layer of a Holostean fish (alligator gar), showed consistently low F content. In those species whose teeth developed in sequential rows, the F content of enameloid increased with progressive tooth development. The serum F levels of all fish were below 0.05 microgram F/mL (2.63 mumol/L) and were not significantly related to the F content of the enameloid. The results substantiate the idea that F incorporation into enameloid is related to fish phylogeny, not food or habitat. It is suggested that specialized outer dental epithelial cell configurations may facilitate the incorporation of F into enameloid.

Animals↗
PubMed1990

The effects of colchicine on the ultrastructure of odontogenic cells in the common skate, Raja erinacae.

Ultrastructural alterations induced by colchicine were investigated to determine the secretory activities of odontogenic cells during formation of tooth enameloid matrix in skates. Treated skate inner dental epithelial (IDE) cells did not display dilated cisternae of the granular endoplasmic reticulum (GER) nor accumulate Golgi-associated secretory granules at any dose level or time interval examined. This response was markedly different from that observed in teleost IDE cells synthesizing the enameloid collagen matrix. Treated skate IDE cells did show increased accumulations of glycogen-containing vesicles and intercellular glycogen associated with amorphous material, compared to controls. Additionally, the aberrant occurrence of large intracellular glycogen pools and amorphous material suggested that carbohydrate processing was a major function of skate IDE cells. Treated odontoblasts associated with enameloid matrix formation sometimes showed dilated GER cisternae, but procollagen secretory granules were not observed. Instead, electron dense material was present within the Golgi cisternae, tubular granules, and large granules. Some electron-dense material appeared to be shunted to a resorptive pathway via multivesicular bodies in treated odontoblasts. The continuity of tubular granules with the enameloid matrix suggested that they contained precursors of the enameloid matrix, and possibly the periodic, 17.5-nm cross-striated, "giant" fibers. Treated odontoblasts associated with predentin collagen matrix deposition showed dilated GER cisternae and accumulations of procollagen secretory granules, features consistent with the function of active collagen synthesis and secretion. The findings indicate that (1) skate IDE cells do not synthesize enameloid collagen as found in bony fish tooth development; (2) skate IDE cells do process glycogen for secretion into the enameloid matrix; (3) collagen, although present, is not a major constituent of skate enameloid matrix; (4) enameloid "giant" fibers are unique to elasmobranchs; and (5) odontoblasts synthesize and secrete proteins other than collagen into the enameloid matrix.

Animals↗
PubMed1990

[Use of the stable nitrogen isotope 15N in assessing liver metabolism in hormonal contraception].

In 37 women with long-term use of oral contraceptives (average use 13.4 years) and 12 women who had not taken oral contraceptives for at least 5 years we determined the serum enzymes ALAT, ASAT, Gamma-GT and conducted the 15N-ammonium test as a marker of partial metabolic performance of the liver. In addition we studied total protein, protein fractions in the serum and haematologic parameter. 18 out of 37 women showed a morbid result in the 15N-ammonium test. In 4 of these 18 women morphological changes representing hepatic damage caused by contraceptives could be detected. On the average ALAT, Gamma-GT and 15N-ammonium test in both groups are clearly different. Because the enzymic levels are being in the normal range, only the 15N ammonium test enables to give a hepatotoxic evidence. It is possible to conclude that long-term use of oral contraceptives influences the liver metabolism.

Adult↗
PubMed1989

The penetration of exogenous tracers through the enameloid organ of developing teleost fish teeth.

In order to determine whether exogenous materials permeate to the forming tooth enameloid matrix, teleost species were injected intramuscularly with horseradish peroxidase (HRP) or myoglobin, or; intracardially with lanthanum nitrate or HRP, then killed a predetermined intervals post-injection. Tooth bearing bones were processed for transmission electron microscopy. At the enameloid matrix formation stage, capillaries associated with the enameloid organ were few in number and rarely fenestrated. Both organic tracers reached the matrix at cervical but not coronal, regions of the teeth in all species examined. Lanthanum was rarely observed extravascularly and never extended to the enameloid matrix at the secretion stage. At the enameloid mineralization stage, fenestrated capillaries were closely associated with the outer dental epithelial cells (ODE). All tracers were observed in the plasma membrane invaginations of the ODE. Only intracardially injected HRP compromised the apical intercellular junctions of the inner dental epithelial cells (IDE) to reach the mineralizing enameloid Lanthanum did not extend past the ODE-IDE cell junctions. It is concluded that the close association of mineralization stage fenestrated capillaries with the highly invaginated ODE cells result in increased tracer penetration compared to the secretory stage. The deeper penetration of the organic tracers, compared with lanthanum, between mineralization stage IDE cells may be due to longer in vivo circulation of the former material. The apical junctions of mineralization stage IDE cells, however, remained impermeable to the organic tracers. The absence of mineral in secretory stage enameloid mineral could not be due to specialized cell junctions preventing access of molecules to the matrix. It is suggested that controlling factors other than cellular permeability initiate enameloid mineralization.

Animals↗
PubMed1986

Combined tracheal transection and innominate artery disruption from blunt chest trauma.

Both transection of the trachea and injury of the aorta and its arch vessels can occur after blunt chest trauma; however, the combination of these injuries in 1 patient is exceedingly rare. This report of a patient with distal trachea transection and proximal innominate artery disruption from blunt chest trauma reviews some of the important factors to be considered in managing these injuries. Management of the airway must be planned before the operative procedure is begun and can be facilitated by the use of a sterile anesthesia circuit passed on to the operative field. Exposure of tracheal injuries as low as the carina can be achieved through sternotomy incision if this approach is indicated for repair of the associated vascular injury. The use of prosthetic materials should be avoided in vascular injury repair due to contamination of the field from the associated airway disruption. Attention to postoperative bronchial hygiene is mandatory for successful outcome after tracheal anastomosis.

Adult↗
PubMed1980

Blood transfusion-induced suppression of cellular immunity in man.

The effect of planned blood transfusions on cell-mediated immunity was studied in previously nontransfused prospective kidney graft recipients. Following transfusion of washed erythrocytes a marked suppression of cellular immunity was found, indicated by reduced response to mitogenic (PHA, Con A, PWM) and antigenic stimulation (Ag-C containing PPD, tetanus toxoid, streptolysin, mumps, vaccinia antigen). A second transfusion led to a more pronounced and prolonged immunosuppression. No suppression was found when autologous blood was applied to volunteers. Preliminary results show autologous and allogeneic MLR suppression when mitomycin-C treated patient cells taken after transfusion are added. Our findings indicate that blood transfusion-induced suppression of cell-mediated immunity might be caused by an unspecific suppressor cell.

Blood Transfusion↗
PubMed1980

Snoring.

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Adult↗