Biomedical subjects

W Drommer

Publications and source records attributed to W Drommer.

At least 19 recordsLinked to original sources

PubMed2003

[Experimental studies on the therapy of epiglottis hypoplasia in horses--transendoscopic injection of collagen and polytetrafluoroethylene].

Epiglottic augmentation by transendoscopic injection of an implant material was performed on ten clinically healthy horses. In six cases bovine collagen (Zyplast) was used, in the remaining four horses the injection was done with polytetrafluorethylene (PTFE-Paste). The results of the surgery were observed endoscopically and by contrast radiography. Using the radiographs, epiglottic length and thickness were measured. For necropsy and histologic assessment the horses, three and two animals of the two groups, were euthanized at three and 12 weeks after surgery. The data obtained from the measurements at necropsy were correlated with those from the radiographs. The minimal invasive technique was very easy to perform with the bovine collagen while PTFE was less suitable for the transendoscopic injection. The data concerning the epiglottic length as well as its thickness measured on the radiographs correlated well to those obtained from the measurements at necropsy. After injection of collagen as well as PTFE an organisation of the implant was noticed histologically, which increased in accordance with the increasing time after injection. As far as the collagen implant is concerned, there was fibrous granulation tissue accompanied by an inflammatory reaction consisting mainly of lymphocytes and histiocytes. In contrast the injection of PTFE led to the development of a foreign body granuloma. In addition, some cases showed ulcers. Both implant materials led to an increase in epiglottic thickness, so that one can expect an improvement in its stability which could be of benefit to the therapy of epiglottic hypoplasia. But this increase in thickness had its maximum level directly after injection and declined over the period observed. Still, especially in the case of the collagen used here, the development of a fibrous granulation tissue and the immigration of fibroblasts and fibrocytes into the implant indicates that there is a stabilisation to some extent. Bovine collagen was proven to be highly suitable for transendoscopic injection. Although there is report about good clinical results using PTFE via laryngotomy, this material seems to be unsuitable for the transendoscopic technique due to the circumstances that lead to a higher number of complications.

Animals↗

PubMed2002

Microscopic and ultrastructural lesions of the ureter and renal pelvis in sows with regard to Actinobaculum suis infection.

Tissues from ureter and renal pelvis of 18 sows naturally (n = 15) and experimentally (n = 3) infected with Actinobaculum suis (former Actinomyces, Eubacterium suis) were studied using light and scanning as well as transmission electron microscopy. The results were compared with the findings from 11 clinically healthy sows as controls. The lesions in both the ureter and renal pelvis of naturally and experimentally infected animals were similar. In severe cases there were necrotizing ureteritis and pyelitis with accumulation of bacterial colonies in some cases. Several superficial epithelial cells were found phagocytosing necrotic debris. In mild cases the main lesions included epithelial cell hyperplasia, desquamation of the superficial epithelial cells and goblet cell metaplasia with intraepithelial cyst formation. The goblet cells were found in the superficial as well as in the intermediate cell layers. Generally, it was observed that severe purulent ureteritis and pyelitis/ pyelonephritis in sows were to be expected only in mixed infection of A. suis with other bacteria. The findings were compared and discussed with the changes in the infected urinary bladder of sows and the alterations induced by urinary tract infection in man.

Actinomyces↗

PubMed2002

Effects of repeated biopsying on muscle tissue in horses.

The collection of muscle samples in horses to estimate their performance potential, adaptations to training and diagnosis of exertional myopathies is of increasing interest. This study was designed to examine whether repeated biopsying of the gluteus medius muscle at 7 week intervals alters morphology and muscle fibre variables in the sampling area. The gluteus had been biopsied 3 times previously, each biopsy separated by a 7 week interval. Seven weeks after the last biopsy, this study was initiated. Percutaneous needle biopsies were taken from left and right muscles at 2 depths (2 and 6 cm) and at 2 sites for each depth (22 and 25 cm from the tuber coxae) of 7 mature Thoroughbreds. The 22 cm site was located close (2 cm caudal) to an area of the muscle that had been biopsied previously. The 25 cm site was 5 cm apart from this area. A total of 52 samples were available for histology, electron microscopy and immunohistochemistry. The latter was used to study percentages, sizes and capillaries of muscle fibre types. Most muscle samples collected (75%) had normal morphology, but the remaining 25% showed signs of muscle repair. In some circumstances, they showed regenerative signs of complete muscle repair, while in others ineffective muscle repair (scar formation) was evident. Nevertheless, sufficient normal tissue was always available for measuring routine muscle variables. Samples collected 3 cm laterally apart showed large differences with regard to muscle fibre type variables examined. These results show that repeated muscle samples in intervals of 7 weeks do not have effects that would impair evaluation of muscle fibre variables for diagnosis of effectivity of conditioning programmes. Furthermore, they emphasise that the only way of keeping variations through sample collection technique small is to standardise all biopsying techniques accurately.

Animals↗

PubMed2001

[Optimizing laser parameters for intrastromal incision with ultra-short laser pulses].

BACKGROUND: With the assistance of ultrashort laser pulses (ca. 200 fs pulse duration) it is possible to perform precise incisions inside the corneal stroma with a width of a few microns. The advantage of ultrashort pulses is that the required energy of a few microjoules is more than an order of magnitude lower compared with longer pulse durations, i.e. ps or ns pulses. Therefore, the secondary effects, such as thermal and mechanical damage to the surrounding tissue and the amount of radiation reaching the retina, are reduced. This method of intrastromal photodisruption allows a very well defined deposition of energy within the laser focus inside the corneal stroma, accompanied by minimal collateral damage. METHODS: The possibilities of performing intrastromal cuts using fs-laser pulses at a wavelength of 780 nm and pulse durations of 200 fs were studied using a titanium-sapphire laser system. The treated tissue samples were analysed by light and scanning electron microscopy to determine incision quality, reproducibility and achievable accuracy. The mechanical side effects of fs-photodisruption inside the surrounding tissue were analysed by pressure measurements using pyroelectric transducers. CONCLUSION: The thermal and mechanical side-effects of this method are very low and comparable to the effects during excimer treatment. Therefore an application of ultrashort laser pulses in refractive surgery appears to be a feasible alternative.

Animals↗

PubMed2001

Kinetic characterization of the changes in protein tyrosine phosphorylation of membranes, cytosolic Ca2+ concentration and viability in boar sperm populations selected by binding to oviductal epithelial cells.

On reaching the oviduct, spermatozoa are retained in the isthmic region of the oviduct until ovulation occurs. The essential steps of capacitation are co-ordinated in this region. In this study, a primary cell culture system of oviductal epithelial cells was established to investigate sperm binding to oviductal epithelium and modulation of sperm function during incubation under capacitating conditions in co-culture with oviductal epithelial cells. Epithelial cells were stripped from the oviducts of sows and cultivated for 5-7 days on Lab-Tek Chamber slides on Matrigel. The preparations on chamber slides and suspensions of control spermatozoa were incubated for 3 h in Tyrode's albumin lactate pyruvate (TALP) medium. At 3, 30, 60, 90 and 180 min the free-swimming spermatozoa were collected by washing, and membrane integrity, tyrosine phosphorylation patterns and [Ca(2+)](i) of bound, unbound and control spermatozoa were assessed with fluorescent probes (propidium iodide, Cy-3 and fluo-3-AM). The cells bound to oviductal epithelial cells showed reduced cytosolic Ca(2+) concentration, reduced and almost absent tyrosine phosphorylation of membrane proteins and higher viability at the time of the first sampling. Increases in Ca(2+) concentration and cell death occurred much more slowly during incubation in cells bound to oviductal epithelial cells compared with free-swimming spermatozoa, and no changes in tyrosine phosphorylation were observed. The preferential binding of viable, low-Ca(2+) cells with suppressed tyrosine phosphorylation and slower functional modulation of boar spermatozoa attached to oviductal epithelial cells might represent a mechanism for selecting functionally competent spermatozoa and prolonging their lifespan by delaying capacitation in the oviductal reservoir.

Animals↗

PubMed2001

Selective sperm binding to pig oviductal epithelium in vitro.

The sperm reservoir in the caudal isthmus of the oviduct of a number of species is created by binding of spermatozoa to oviductal epithelium. The sperm reservoir fulfills a number of functions such as control of sperm transport, maintenance of sperm viability and modulation of capacitation. The initial capacities of ejaculated and epididymal boar spermatozoa to bind to oviductal epithelium were investigated using a modified pig oviductal explant assay. The number of spermatozoa that bound to 0.01 mm(2) of explant surface was used as the parameter of binding capacity. Binding of spermatozoa to oviductal epithelial explants was dependent in a linear manner on the number of spermatozoa added (P < or = 0.05). No difference was found in initial sperm binding between isthmic and ampullar explants. There was no effect of the stage of the oestrous cycle or the reproductive status of the female donor. There was a significant effect (P < or = 0.05) of the individual boar on the binding index. The binding index correlated negatively with the percentage of spermatozoa with cytoplasmic droplets and the percentage of morphologically abnormal spermatozoa (P < or = 0.05). Epididymal spermatozoa showed significantly lower initial binding capability than did ejaculated spermatozoa from the same boars (P < or = 0.05); therefore, components of seminal plasma may play a role in the binding process. The individual differences revealed by this study and their relation to morphology and contact of spermatozoa with seminal fluid indicate a selective function of sperm-oviduct binding.

Animals↗

PubMed2000

Cytopathological observations on renal tubule epithelium cells in common carp Cyprinus carpio under Trypanoplasma borreli (Protozoa: Kinetoplastida) infection.

Cytological alterations in renal tubule epithelium cells of carp Cyprinus carpio infected with the blood flagellate Trypanoplasma borreli Laveran & Mesnil, 1901 were investigated during the course of a laboratory infection of a highly susceptible carp line. With the development of the parasitaemia, a hyperplasia of the interstitial renal tissue was induced, which resulted in a tubulus necrosis. Cytological changes were already seen in tubulus epithelium cells on Day 7 post injection (PI) of the parasite. The basilar invaginations of the cells fragmented and a swelling of mitochondria was noted. With increasing parasitaemia, on Days 14 and 21 PI, these changes progressed up to the loss of the basilar invagination and high amplitude swellings of mitochondria and deterioration of their internal membrane structures. Cells of the distal tubule segment reacted earlier and more rapidly than cells of the proximal tubule. The cytological alterations suggested a loss of function of the epithelum cells, which most likely resulted in impaired ionic and osmotic regulation of T. borreli-infected fishes. Our findings indicate that in response to the proliferation of the interstitial renal tissue cell structures of the renal tubule cells are altered quickly and in a progressive manner.

Animals↗

PubMed2000

A study of sequential histopathology of Trypanoplasma borreli (Protozoa: Kinetoplastida) in susceptible common carp Cyprinus carpio.

The tissue response of common carp Cyprinus carpio to the kinetoplastid blood parasite Trypanoplasma borreli Laveran & Mesnil, 1901 was investigated during a laboratory infection of a highly susceptible carp line. With the development of the parasitaemia an increased proliferation of the lymphoid renal interstitial tissue was induced, which resulted in a progressive depression and deterioration of renal tubules. In heavily infected carp at Days 20 to 28 post inoculation (PI), a tubulonephrosis, a glomerulitis caused by a massive accumulation of leukocytes in glomerular capillaries, and large numbers of trypanoplasms in blood vessels and renal interstitium were observed. Corresponding with rising T. borreli numbers in the peripheral blood, splenic lymphocytes showed increasing proliferation rates, and the capillaries of the liver, gills, heart and intestine were infiltrated with lymphocytes and trypanoplasms. In heavily infected carp, congestion of liver sinusoids, focal necroses of hepatic tissue, extensive accumulations of erythrocytes in the spleen and in the blood marked anaemia were observed. These carp often showed abdominal distension, exophthalmus and swimming disorders described as 'sleeping sickness of carp'. Proliferation of cells from the interstitial lymphoid tissue of the kidney, which bears a close resemblance to the bone marrow of higher vertebrates, is considered a normal immune response of fish to antigen challenge. We here describe the unique case of a severe but ineffective immune reaction which results in the destruction of excretory renal structures. This has to be considered a severe disturbance of osmoregulation in affected carp, which, together with a decrease in oxygen uptake due to anaemia, is likely a major cause of death in these carp.

Animals↗

PubMed2000

Application of ultrashort laser pulses for intrastromal refractive surgery.

BACKGROUND: Recently, laser systems have become available which generate ultrashort laser pulses with a duration of 100-200 femtoseconds (fs). By generating micro-plasmas inside the corneal stroma with fs pulses, it is possible to achieve a cutting effect inside the tissue while leaving the anterior layers intact. The energy threshold to generate a micro-plasma with fs pulses is some orders of magnitude lower than it is for picosecond or nanosecond pulses. This results in a strong reduction of the thermal and mechanical damage of the surrounding tissue. METHODS: With a titanium:sapphire fs laser system, the cutting effect on corneal tissue from freshly enucleated porcine eye globes was investigated with different pulse energies. The irradiated samples were examined by light and electron microscopy. The laser-induced pressure transients and the laser-induced bubble formation were analysed with a broadband acoustic transducer and by flash photography. RESULTS: With fs laser pulses, the extent of thermal and mechanical damage of the adjacent tissue is in the order of 1 microm or below and therefore comparable with the tissue alterations after ArF excimer laser ablation. Using pulse energies of approximately 1-2 microJ and a spot diameter of 5-10 microm, intrastromal cuts can be performed very precisely in order to prepare corneal flaps and lenticules. CONCLUSION: Femtosecond photodisruption has the potential to become an attractive tool for intrastromal refractive surgery.

Animals↗

PubMed2000

Corneal dermoid in a dwarf rabbit (Oryctolagus cuniculi).

Histology after superficial keratectomy verified our diagnosis of corneal dermoid in a dwarf rabbit (Oryctolagus cuniculi). To our knowledge, this lesion has not been reported previously to occur in dwarf rabbits. Ocular dermoids should be considered as a differential diagnosis for corneal abnormalities in the rabbit.

Animals↗

PubMed1998

Changes of intestinal epithelial structure and cell turnover in carp Cyprinus carpio infected with Goussia carpelli (Protozoa: Apicomplexa).

Epithelial cell turnover in the intestine of common carp Cyprinus carpio infected with the coccidian parasite Goussia carpelli (Leger & Stankovitch, 1921) was investigated during laboratory infection using histological and electron microscopical techniques. During the development of the parasite an increased number of mitotic enterocytes, identified by bromodeoxyuridine (BRDU) uptake, were observed at the base of infected mucosal folds. During the merogonic and gamogonic development of the parasite, severe damage to infected epithelium occurred, and concomitantly BRDU-positive cells spread along the mucosal folds. These cells exhibited immature characteristics, including a squamous to cuboidal shape, nuclear apolarity, a high number of ribosomes, and short or reduced microvilli. Contact with adjoining cells was formed by tight junctions and desmosomes, indicating the epithelial origin of these cells. These cells covered gut segments with damaged epithelium within a few days, suggesting a high regenerative capacity of the carp intestine, and this could explain the mild clinical symptoms in fish affected by G. carpelli-coccidiosis. Our study for the first time describes epithelial cell responses to injuries caused by enteric protozoa in piscine hosts.

Animals↗

PubMed1998

Alterations of synovial tissue and their potential role in the deposition of beta2-microglobulin-associated amyloid.

BACKGROUND: Beta-2-microglobulin-associated amyloidosis (AB2M) is a frequent complication of long-term dialysis treatment. Uraemic retention of beta2-microglobulin (beta2M) apparently constitutes the basis for AB2M. However, it is unclear why clinical manifestations are largely confined to osteoarticular tissues. It has been speculated that synovial inflammatory changes, induced by uraemia and/or dialysis therapy could predispose this tissue to amyloid deposition. METHODS: We investigated which local synovial alterations preceded or paralleled amyloid deposition. Using immunohistology we evaluated synovial leukocyte infiltration (B and T lymphocytes, monocytes/macrophages), cell proliferation, fibroblast activation (de novo expression of alpha-smooth-muscle actin), the expression of extracellular matrix components (heparan sulphate proteoglycan, collagen types I, III, IV), and advanced glycation end-products (AGEs). RESULTS: Synovial AB2M was detected in 20 of 36 chronic peritoneal and haemodialysis patients and none of eight non-uraemic controls. Notably, non-AB2M synovial amyloid was present in six additional dialysis and three control patients. Cellular infiltration was largely restricted to patients with advanced AB2M deposits. The infiltrates consisted mainly of macrophages and progressed with increasing degrees of AB2M deposition. In advanced cases they exhibited characteristics of a foreign-body reaction. Other infiltrating leukocyte types, altered cell proliferation, or fibroblast activation were absent or uncommon in periarticular tissue of dialysis patients with and without AB2M. Neither dialysis treatment nor the presence of AB2M deposits appreciably altered the qualitative matrix composition in periarticular tissue. AGEs were present in AB2M deposits, the extracellular synovial matrix of dialysis patients (of both, patients with and without AB2M) and, to a lesser degree, in synovia of controls. CONCLUSIONS: These data suggest that, except for AGE formation, alterations of none of the parameters assessed, and in particular no inflammatory tissue alterations, precede periarticular AB2M. Rather synovial tissue, possibly modified by AGEs, seems to have an intrinsic propensity for amyloid deposition and inflammatory changes appear to only arise secondary to amyloid deposition.

Adult↗

PubMed1998

Histology and ultrastructure of the urothelium lining the ureter and the renal pelvis in sows.

The histology and ultrastructure of the urothelium lining the ureter and renal pelvis in sows was examined using light microscopy, and scanning and transmission electron microscopy. The epithelium of both the ureter and the renal pelvis were similar and consisted of the basal, the intermediate and the superficial cells. The luminal surface of the superficial cells was characterized by microplicae. Transmission electron microscopy showed that the luminal membrane of these cells showed trilaminar asymmetric unit membrane. Tight junctions linked the lateral parts of the superficial cells, while the intermediate and the basal cells were connected to each other and the basal cells with the basal membrane through desmosomes and hemidesmosomes, respectively. Clusters of mitochondria were observed throughout the urothelium. Unlike that of the basal cells, the Golgi complex and the endoplasmic reticulum were well developed in the superficial and intermediate cells. Lysosomes and vesicles were observed only in the superficial and the intermediate cells. Fine cytoplasmic filaments, although very few in the basal cells, were observed throughout the epithelium. The results are compared and discussed with the findings reported on the urotherlium of other mammalian species and humans.

Animals↗

PubMed1998

Immunohistochemical studies in equine recurrent uveitis (ERU).

Despite extensive clinical research, the etiology of equine recurrent uveitis (ERU) is still unknown. After an immunologic pathogenesis was established in recurrent uveitis in humans, a similar pathogenic mechanism was assumed to exist in ERU. To investigate whether immunopathologic mechanisms are involved in ERU, 20 eyes of 15 horses with ERU were examined immunohistochemically with a T cell marker, B cell marker, and anti-major histocompatibility complex (MHC) class II antibodies. Twenty-six eyes of 20 horses were used for investigation of MHC class II antigen expression in normal equine eyes. In 18 eyes of 14 horses, the number of T cells in the inflammatory cell population within the uvea was assessed. In 16/18 eyes (89%), the T lymphocyte fraction was > 70%. This cell population was distributed mostly in a diffuse manner throughout the uvea and also within the mantle zone of follicular lymphocytic aggregates. Foci of B lymphocytes could be found within the center of follicular aggregates in three eyes. The expression of MHC class II antigen on resident ocular cells was evaluated in 10 eyes of six horses with ERU. An increase of MHC class II antigen expression in the trabecular meshwork and on the nonpigmented ciliary epithelium was noted as was a deviant expression on proliferating Müller cells and retinal pigment epithelial cells. The predominance of T cells in the inflammatory infiltrates supports the central role of a cell-mediated immune response. Furthermore, the observation of a deviant MHC class II expression on resident ocular cells suggests that aberrant immune regulation may play a role in the pathogenesis of ERU.

Animals↗

PubMed1997

Ultrastructural and molecular analyses of the persistence of Chlamydia trachomatis (serovar K) in human monocytes.

Previous studies have suggested that monocytes may play a role in the dissemination of Chlamydia trachomatis, and in establishment of persistent infection with this bacterium. Infection of cultured human peripheral blood monocytes with C. trachomatis serovar K produced persistent, nonproductive infection. Transmission electron microscopy of such infected cultures revealed single or multiple Chlamydia in monocyte inclusions over a culture period of 10 days. Those inclusions were aberrant, and normal reticulate bodies within the inclusions were not observed. Immunoelectron microscopy showed the chlamydial major outer membrane protein and lipopolysaccharide to be associated with the bacterial plasma membrane. Lipopolysaccharide was also identified in the monocyte cytoplasm. Molecular analyses of primary chlamydial rRNA transcripts demonstrated that the organism is viable and metabolically active within monocyte inclusions. However, attempts to overcome chlamydial growth arrest by incubation of Chlamydia-infected monocytes with tryptophan, and antibodies against alpha interferon, gamma interferon, or tumor necrosis factor, were all ineffective, suggesting that known mechanisms of growth inhibition do not hold in human monocytes. These observations indicate that infection of human peripheral blood monocytes with C. trachomatis may be involved in the genesis/maintenance of extra-urogenital inflammation, since non-culturable, metabolically active bacteria persist in those cells.

Antibodies, Blocking↗

PubMed1997

Comparative studies on mammalian Müller (retinal glial) cells.

Müller cells from 22 mammalian species were subjected to morphological and electrophysiological studies. In the 'midperiphery' of retinae immunocytochemically labeled for vimentin, estimates of Müller cell densities per unit retinal surface area, and of neuron-to-(Müller) glia indices were performed. Müller cell densities were strikingly similar among the species studied (around 8000-11,000 mm-2) with the extremes of the horse (< or = 5000 mm-2) and the tree shrew (> or = 20,000 mm-2). By contrast, the number of neurons per Müller cell varied widely, being clustered at 6-8 (in retinae with many cones), at about 16, and at up to more than 30 (in strongly rod-dominated retinae). Isolated Müller cell volumes were estimated morphometrically, and cell surface areas were calculated from membrane capacities. Müller cells isolated from thick vascularized retinae (carnivores, rats, mice, ungulates) were longer and thinner, and had smaller volumes but higher surface-to-volume ratios than cells from thin paurangiotic (i.e. with blood vessels only near the optic disc) or avascular retinae (rabbits, guinea pigs, horses, zebras). In whole-cell voltage-clamp studies, Müller cells from all mammals studied displayed two dominant K+ conductances, inwardly rectifying currents and delayed rectifier currents. TTX-sensitive Na+ currents were recorded only in some species. Based on these data, the following hypotheses are presented, (a) neuron-to-(Müller) glia indices are determined by precursor cell proliferation rather than by metabolic demands; (b) Müller cell volumes depend on available space rather than on the number of supported neurons; and (c) it follows that, the specific metabolic activities of Müller cells must differ greatly between species, a difference that may contribute to distinct patterns of retinal vascularization.

Animals↗

PubMed1997

Observations on the fine structure of the liver in the camel (Camelus dromedarius).

The structure of macroscopically inconspicuous livers in 23 adult camels (Camelus dromedarius) was studied by light and transmission electron microscopy. A well-developed connective tissue characterizes the camel liver. Thick trabeculae divide the liver parenchyma into lobules. Portal tracts and central veins are surrounded by a variable amount of fibrous tissue. In the perisinusoidal space (DISSE), collagen fibres form a dense three-dimensional network around the sinusoids. A mild to moderate fatty infiltration is present in hepatocytes of all animals. In the epithelial cells of the bile ducts, small to medium sized lipid inclusions are a common feature. The ultrastructure of hepatocytes in the camel liver corresponds to that of other domestic mammalian species. The endothelial cells lining the sinusoids show a multiple fenestration and are surrounded by a discontinuous basal lamina. Fat-storing cells are numerous and contain lipid droplets varying in size, number and electron density from one cell to another.

Animals↗

PubMed1997

[Intraocular metastasis of bronchial carcinoma in a cat].

A rare case of a ten-year-old neutered male Persian cat is described, in which metastasis of a pulmonary adenocarcinoma into the choroid of the right eye had led to visual impairment and major ophthalmoscopically detectable changes of the fundus. These were a generalized hyporeflectivity of the tapetal fundus due to retinal edema with multiple areas of retinal detachment and also severe edema of the papilla, furthermore an increased tortuosity and congestion of the retinal vessels. While the diagnosis of a primary lung tumor could be made intra vitam based on the result of an x-ray examination, the neoplastic nature of the fundic lesions could only be confirmed by histopathologic examination.

Adenocarcinoma↗