Biomedical subjects

P Böck

Publications and source records attributed to P Böck.

At least 19 recordsLinked to original sources

PubMed2006

Animal experiments with ultra-high molecular weight polyethylene (UHMW-PE) stabilised with alpha-tocopherol used for articulating surfaces in joint endoprostheses.

Numerous investigations proved the impressive suitability of alpha-tocopherol as a stabilizer for ultra-high molecular weight polyethylene (UHMW-PE) used for endoprostheses. Regarding the biocompatibility of this new biomaterial, in-vitro celltoxicity tests gave no hint for a cyto- or genotoxic activity. In this study, animal experiments are carried out to further ensure the biocompatibility of this biomaterial. Thin UHMW-PE-films (20 x 6 x 0.23 mm3) were implanted subcutaneously into rats. Morphology and reactivity of surrounding connective tissue against either pure UHMW-PE material or UHMW-PE containing alpha-tocopherol were studied at timed intervals (2 weeks, 3 month, and 6 month after operation) in 3 groups of animals, each group comprising 10 animals. Parallel to these tests, material changes were investigated in these 3 groups of 10 animals at the same intervals after operation with the help of infrared spectroscopy (FTIR). Within the implantation time, no noteworthy oxidative degradation could be observed. The amount of lost alpha-tocopherol due to diffusion is low enough to ensure a lifetime stabilisation of the UHMW-PE. The implants were all well tolerated and definitely encapsulated already 2 weeks after operation. Presence or absence of alpha-tocopherol in the implants did not evince morphological differences. Therefore, negative consequences were not manifest in the presence of alpha-tocopherol.

Animals↗

PubMed2006

Mammary gland secretory concretions contain non-collagenous bone matrix proteins.

Secretory concretions in mammary gland alveoli are commonly of microscopical size. However, some concretions reach clinically palpable dimensions and may occlude teat canals and obstruct milk flow. We studied secretory concretions in sheep, goat and cow mammary glands, using routine histological staining methods, conventional histochemistry and electron microscopy. As concretions frequently mineralize, immunostaining for keratan sulphate and calcium-binding non-collagenous bone matrix proteins (bone sialoprotein, osteocalcin, osteonectin and osteopontin) was performed. Concretions consisted of organic matrix (condensed secretions) with calcium precipitates. Mineralized deposits mostly show concentric organization, bound haematoxylin, and were readily identified in H&E-stained sections. Mineral components of concretions reacted for calcium carbonate and phosphate, organic matrix was found to contain sialoglycan material. Immunohistochemistry revealed bone sialoprotein, osteonectin and keratan sulphate in cow and goat concretions. Osteocalcin was detected in sheep, cow and goat concretions, whilst osteopontin was not identified in any of the specimens studied. Our results indicate the presence of non-collagenous bone matrix proteins (except osteopontin) in mammary gland concretions. These glycoproteins are commonly thought to govern mineralization of organic matrix and are assumed also to promote mineral deposition in mammary gland secretory concretions. Besides caseins, these particular glycoproteins have to be considered as calcium-binding milk proteins.

Animals↗

PubMed2005

Digital cushions in horses comprise coarse connective tissue, myxoid tissue, and cartilage but only little unilocular fat tissue.

Digital cushions were studied in horses with particular reference to vascularization, tissue constituents and matrix components. The cushions mainly resembled a network of coarse collagen bundles. The areas inbetween the bundles were replenished with loosely woven interstitial connective tissue, myxoid tissue, and fibrocartilage. Expected masses of fat lobules were missing: only solitary adipocytes or small groups of adipocytes were seen. Vascular supply to the cushions was remarkably poor. The mucinous myxoid matrix largely consisted of hyaluronan with little sulphated glycosaminoglycans. Myxoid cells were stellate or ramified in shape and showed a tendency to store glycogen and lipid droplets. Myxoid cells reacted for vimentin and stained for S-100 protein. Moreover, myxoid cells often reacted for neuron specific enolase and glial fibrillary acidic protein. Myxoid tissue continuously transformed into loosely organized interstitial connective tissue with fibroblasts, which remained unreactive when tested for neuroectodermal markers. Myxoid tissue also was not clearly demarcated against irregularly interspersed islets of fibrocartilage or hyaline cartilage. Chondrocytes did not stain for neuron specific enolase but reactivity for S-100 protein and glial fibrillary acidic protein was noted in peripheral regions of fibrocartilage. Single or grouped unilocular fat cells were rarely placed into myxoid areas. Unilocular fat cells stained for vimentin, S-100 protein, and occasionally for glial fibrillary acidic protein but not for neuron specific enolase. Continuous transformation of myxoid tissue into cartilage together with corresponding reactivity for neuroectodermal marker proteins of myxoid cells and peripherally located chondrocytes suggest close relationship between myxoid cells and chondrocytes. The same criteria indicate relationship between myxoid cells and adipocytes. Coarse connective tissue, myxoid tissue, fibrous cartilage, and fat cells are functionally combined to absorb mechanical shock in the horse digital cushions.

Adipose Tissue↗

PubMed2001

Immunohistochemical demonstration of Leu-7 (HNK-1), Neurone-specific Enolase (NSE) and Protein-Gene Peptide (PGP) 9.5 in the developing camel (Camelus dromedarius) heart.

The development of the heart-conducting system has been controversially discussed. The common opinion that these specialized myocytes originate from mesodermal precursors has been challenged when nerve-specific antigens (Leu-7, NF, GIN2) were demonstrated in embryonic hearts of various species, suggesting a neural crest contribution to the embryonic conducting tissue. Anti-Leu-7 (HNK-1) antibodies were reported to reliably mark the conducting system in developing rat, chicken and human hearts. The present investigation was carried out on the hearts of 15 camel fetuses at 35, 45, 60, 75 and 100 cm crown-rump length (three specimens for each stage), in addition to three adult hearts. We investigated the antigenicity of cardiac structures for Leu-7, NSE (Neurone specific Enolase) and PGP (Protein Gene Peptide) 9.5. In all specimens investigated, both NSE and PGP 9.5 were expressed by cardiac nerves and conducting system components. The sinuatrial and atrioventricular nodes, the atrioventricular bundle as well as subendocardial and intramyocardial Purkinje fibers were stained. In contrast, the developing conducting system did not react with anti-Leu-7 antibody, although Leu-7 antigenicity was strongly expressed by the developing cardiac nerves. In adult camel hearts, the same pattern of immunoreactivity for the markers studied was still retained. Our results show that the expression of marker proteins for the developing conducting system is species-specific. Therefore, these markers are of little significance in discussions on the possible neurogenic nature of the heart conducting tissue.

Animals↗

PubMed2000

Different modes of degeneration in autologous and heterologous heart valve prostheses.

BACKGROUND AND AIM OF THE STUDY: This study was performed to elucidate the mechanism of primary tissue failure of bioprosthetic heart valves, which were fabricated from autologous pericardium (Autogenics). Results were compared with the degeneration pattern of heterologous pericardial bioprostheses. METHODS: Between March 1994 and December 1996, 87 Autogenics heart valves were implanted in the aortic position. Since then, 15 valves had to be explanted due to structural deterioration. The average implant period was 33+/-8 months. All explants were examined by gross morphological evaluation and X-ray analysis to identify the failure mode of these devices. In eight explanted autologous tissue valves and six explanted heterologous pericardial bioprostheses, exact morphological evaluation was performed by scanning electron microscopy, microscopic and immunohistochemical techniques. RESULTS: All autologous tissue valves failed due to cuspal tears localized at the commissures. Nocalcification could be detected by X-ray analysis and microscopic methods. Endothelial cell coverage was evident at the outflow surface of all autologous bioprostheses. Histological examination showed severe disintegration of the collagen fibers by insudated plasma proteins and erythrocytes, and the absence of the original fibroblasts. Collagen fibers were vigorously altered between the inner and outer stent of the Autogenics valve. In contrast, heterologous pericardial valves failed due to severe calcification of the cusps. Histological evaluation displayed invasion of macrophages and calcific deposits. The collagenous texture of the pericardial tissue was significantly better preserved compared with autologous tissue. CONCLUSION: High biocompatibility of autologous tissue valves is indicated by the absence of calcium deposits, macrophages and foreign body giant cells, and the presence of endothelial cell ingrowth. Severe disintegration of autologous tissue suggests that brief immersion in glutaraldehyde generates inadequate mechanical stability of bioprosthetic heart valve material. Heterologous valves exhibit low biocompatibility but superior preservation of the collagenous biomaterial.

Aged↗

PubMed1999

Memantine for prevention of spinal cord injury in a rabbit model.

BACKGROUND: This study was conducted to investigate the effect of memantine, a noncompetitive N-methyl-d-aspartate receptor antagonist, on the neurologic outcome of spinal cord ischemia after aortic occlusion. MATERIALS AND METHODS: New Zealand White rabbits were anesthetized and spinal cord ischemia was induced for 40 minutes by infrarenal aortic occlusion. Animals were randomly allocated to 3 groups. Group 1 (n = 8, control) received no pharmacologic intervention, group 2 (n = 8) received intra-aortic memantine infusion (20 mg/kg) after aortic crossclamping, and group 3 (n = 8) was treated with systemic memantine infusion (20 mg/kg) 45 minutes before aortic occlusion. Neurologic status was scored by the Tarlov system (in which 4 is normal and 0 is paraplegia) at 12, 24, 36, and 48 hours after the operation. Lumbar spinal root stimulation potentials and motor evoked potentials from lower limb muscles were monitored before, during, and after the operation. After the animals were killed, the spinal cords were studied histopathologically. RESULTS: All potentials disappeared shortly after aortic crossclamping. They returned earlier in both memantine-treated groups than in the placebo group. Histologic examination of spinal cords revealed a few abnormal motor neurons in memantine-treated rabbits but found extensive injury in the control group. At 12 hours the median Tarlov scores were 0 in the control group (group 1), 2 in the intra-aortic memantine group (group 2, P =.001 versus control), and 3 in the systemic group (group 3, P =.0002 versus control). At 24 hours median Tarlov scores were 0, 2.5 (P =.0002), and 4 (P =. 0002), respectively. Finally, at both 36 and 48 hours median Tarlov scores were 0, 3 (P =.0006), and 4 (P =.0002), respectively. CONCLUSION: Memantine significantly reduced neurologic injury related to spinal cord ischemia and reperfusion after aortic occlusion.

Animals↗

PubMed1998

Endothelialization of biosynthetic vascular prostheses after laser perforation.

OBJECTIVE: This study was undertaken to investigate the feasibility of transmural capillary ingrowth into the inner surface of biosynthetic vascular prostheses (Omniflow, BioNova, Melbourne, Australia) through perforations created by an excimer laser, thus inducing an endothelial cell coverage. METHOD: Biosynthetic vascular prostheses (Omniflow, 10 cm length, 6 mm diameter) were perforated with an excimer laser (diameter of the holes 50 to 100 microm, distance 4 mm) and implanted into the carotid arteries of eight sheep. They were compared to untreated Omniflow prostheses implanted at the contralateral side. Three months after implantation the prostheses were explanted and evaluated by gross morphology, histologic examination, scanning electron microscopy, and immunohistochemical staining for factor VIII to identify endothelial cells. RESULTS: All grafts remained patent. Gross morphologic examination revealed no significant difference in the thrombus-free surface between perforated and untreated prostheses. However, scanning electron microscopy showed endothelial cells in the midgraft portion of all perforated prostheses, whereas collagen fibers, fibrin meshwork, and activated platelets formed the inner layer in six of eight untreated Omniflow prostheses. Transmural capillary ingrowth in the laser group was verified by positive factor VIII staining for endothelial cells in the laser channels. CONCLUSION: Spontaneous endothelialization of biosynthetic vascular prostheses can be achieved by transmural capillary ingrowth through perforations in the wall of the prostheses in an experimental sheep model.

Anastomosis, Surgical↗

PubMed1998

Alteration of rat cerebral microvascular eicosanoid formation by isradipine, a calcium channel blocker.

We studied the influence of the calcium channel blocker isradipine on cerebral microvascular and aortic eicosanoid synthesis. The rat cerebral microvascular eicosanoid formation was assessed by means of bioassay, radioimmunoassay and radio thin layer chromatography from endogenous as well as from exogenous (20:4) radiolabelled substrate. The in vitro as well as the in vivo (0.3 mg/kg/day for 1 week) effect of isradipine was examined. Isradipine increased significantly (P < 0.01) both conversion to and formation of PGI2 and its derivative 6-oxo-PGF1alpha respectively, as well as PGD2-production, while TXB2-synthesis was diminished. The conversion to the other metabolites was not affected to a significant extent. These findings indicate that isradipine enhances PGI2-generation in aorta and cerebral microvessels from both exogenous and endogenous substrate and PGD2 from endogenous substrate, a phenomenon shown to underlie the antiatherosclerotic actions of this calcium channel blocker.

6-Ketoprostaglandin F1 alpha↗

PubMed1998

Acidic glycoproteins accumulate in calcified areas of bioprosthetic tissue.

BACKGROUND AND AIMS OF THE STUDY: This study was performed to evaluate the role of collagen fibrils, cellular elements and matrix proteins in calcification of glutaraldehyde (GA)-fixed bioprosthetic material. METHODS: Lyoplant (lyophilized bovine pericardium, type I collagen) was processed according to three protocols. DF-group (double fixation): after conventional fixation in GA (0.5% for 72 h; storage 0.25%) Lyoplant was implanted subcutaneously into rats for 5 days. Specimens were explanted and re-fixed (conventional fixation), followed by autologous or homologous reimplantation in rats for 21 or 63 days. CF-group (conventional fixation): Lyoplant patches were conventionally fixed (as DF-group), kept in 0.9% saline for one week, and then autologously and homologously reimplanted. GF-group (high-concentration GA): Lyoplant patches were processed (as GF-group) but 0.5% GA was used for tissue storage. Explanted specimens were studied by light microscopic histochemistry; calcium contents were measured by atomic absorption spectroscopy. RESULTS: Severe calcification occurred in the DF-group without differences between autologous and homologous reimplantation. In CF- and GF-groups, calcification was negligible, but immunologic response against homologous implants was accompanied by increased calcium content. Histologic characterization of matrix material in calcified areas revealed oxyphilic glycoproteins, identified as sialoglycans. CONCLUSIONS: Modification of extracellular matrix by GA is assumed as essential to cause calcification of bioprosthetic material. Calcium deposition and accumulation of sialoglycans are simultaneous events. A specific role of this glycoprotein for calcification has to be considered.

Analysis of Variance↗

PubMed1998

Lectin histochemistry of fallopian tube epithelial cells. Relation to ovum transport and ovum pickup.

OBJECTIVE: Data on histochemical and biochemical characteristics of the human oviduct are scarce. The exact mechanisms of ovum transport and pickup are not fully understood. STUDY DESIGN: Human fallopian tubes were obtained and prepared for histochemistry. We analyzed the distribution of negatively charged groups on the oviduct epithelium and cumulus cells and examined the distribution of glycoconjugates by means of lectin histochemistry. We tested the possible influence of poly-L-lysine and considered ABO blood group expression since these characteristics are determined by specific terminal sugar residues. RESULTS: A negatively charged glycocalyx exists on tubal epithelial cells and cumulus cells. Adherence by affinities similar to sugar-lectin binding forces could be disproven in case of commonly used lectins. Poly-L-lysine inhibited the cationic binding reaction but did not influence lectin binding. The blood group A glycoprotein presents terminal D-N-acetyl-galactosamine residues, which are demonstrated by HPA lectin binding. CONCLUSION: Our study indicates that it is unlikely that electrostatic interactions play a major role in ovum transport or pickup. Since poly-L-lysine has been described as inhibiting ovum transport, sugar-lectin binding affinities seem not to operate in ovum transport or pickup.

ABO Blood-Group System↗

PubMed1997

Expression of glial and neuronal marker proteins (S-100, glial fibrillary acidic protein, and neuron-specific enolase) by myxoid cells in the human larynx.

Areas of myxoid connective tissue were regularly found in the aryepiglottic and vestibular folds of operative resections (n = 10) or fresh postmortem specimens (n = 5) of the human larynx. Myxoid tissue was often attached to elastic cartilage (epiglottic, arytenoid, and corniculate cartilage) or spatially related to mucosal glands. This was characterized by ramified cells (myxoid cells) in an ample acidic matrix with few strands of collagen fibers. Extracellular matrix showed alcianophilia at pH 2.5 and metachromasia while tissue digestion with hyaluronidase abolished these staining reactions. Immunohistochemistry revealed reactivity of myxoid cells for S-100 alpha and S-100 beta protein, glial fibrillary acidic protein, and neuron-specific enolase. Elastic cartilage chondrocytes also stained for these markers while fibroblasts remained unstained. Reactivity for identical-neuroectodermal marker proteins of myxoid cells and chondrocytes indicated their close relationship. The presence of myxoid tissue in the larynx, as evidenced by stellate cells immunoreactive for neuroectodermal marker proteins, should be considered when using these markers in diagnostic pathology.

Chondrocytes↗

PubMed1997

Sphincters of canine hepatic sublobular veins respond to endothelin-1 and 3.

The dog has been used repeatedly as a model in liver transplantation research. The microcirculation and its regulatory mechanisms play a crucial role during ischemia and reperfusion. Little is known about the role of venous sphincters in regulating blood flow in the dog liver. Hence, we performed this study to elucidate their potential role in regulating local blood flow. In 14 dogs mean systemic (MSP) and mean portal venous pressure (MPP) were measured. Light and electron microscopy (scanning and transmission) of tissue sections and vascular corrosion casts were used to elucidate the microvascular morphology. Immunocytochemistry was applied to identify smooth muscle cells and the innervation of venous sphincters. Endothelins 1 and 3 were injected to find whether the hepatic venous sphincters are sensitive to these vasoactive agents. Tufts of smooth muscle cells were found in the sublobular veins (SLV; 100 to 250 microm in diameter), that reduced the luminal diameters of veins by 34%. Nerve endings were not observed close to these venous sphincters. The MSP and MPP were 75.3+/-2.4 mmHg and 8.9+/-0.95 mmHg, respectively. Treatment with 1.0 microg/kg of endothelin-1 (ET-1) significantly increased the MSP, the MPP and the percentage of focal venous sphincter contraction by 39% (105+/-4.7 mmHg), 43% (12.8+/-1.7 mmHg) and 57% (53.5+/-4.7), respectively (P <0.01). Treatment with ET-3 caused a significant (P <0.01) decrease in the MSP, the MPP and the percentage of sphincter contraction by 19% (61.0+/-2.2 mmHg), 39% (5.8+/-2.9 mmHg) and 38% (20.9%+/-3.15). Sinusoids did not contain sphincters. Hepatic arterioles and central veins were not affected by ET-treatment. The contraction of SLV sphincters correlated with increases in MPP (r=0.81, P <0.01) and was related to the MSP (r=0.67, P <0.01). These data show that the smooth muscle sphincters in SLV of the dog liver are involved in the local regulation of blood flow and that these sphincters are stimulated by non-neurogenic mechanisms. These sphincters contract in response to ET-1 and relax in response to ET-3. Since ET-1 is released during and/or causes inflammation, e.g., during ischemia and reperfusion, its antagonists might be of benefit during transplantation reperfusion of liver.

Actins↗

PubMed1997

The microvenous valvular anatomy of the human dorsal thoracic fascia.

The use of free scapular fasciocutaneous flaps for reconstruction of recalcitrant grade 6 venous stasis ulcers has shown excellent early success rates. Venous refilling times measured postoperatively over the flaps by photoplethysmography have noted improvements to normal levels. Preliminary anatomic studies have demonstrated valves in the circumflex scapular veins of flaps used in reconstruction. The purpose of this study was to investigate and document the number, morphology, size, and location of valves in the human dorsal thoracic fascia. Ten scapular flaps were obtained from unembalmed cadavers and injected with methyl methacrylate. Each flap cast was divided into four parts: proximal, right and left, and distal, right and left. We reduced the size of specimens (the largest being 24 x 11 mm) and studied them in a scanning electron microscope. We identified all valves, estimated the diameter of the corresponding vein, calculated the depth of the valvular sinus, and related it to the corresponding venous size. Light microscopy and transmission electron microscopy were used as assisting tools applied to glutaraldehyde-fixed specimens. Analysis of injected specimens showed that valves were most abundant in veins with a luminal diameter of 30 to 120 microns (59.3 percent of 905 valves). The depth of valves became larger with increasing venous diameter. The sizes of valve sinuses were not different for individual valves. Except for veins larger than 1000 microns in diameter, there was no significant difference between the number of valves in different parts of an individual flap, nor were there significant differences between the valve numbers in different flaps. Most valves were bicuspid; only in the vein category of 30 to 120 microns were unicuspid valves encountered. Valves sometimes were located in series in a short segment of a vein; occasionally, they were found at the merging site of two veins. Transmission electron microscopy showed that valve leaflets had collagen fibers that ascended toward the tip of the leaflet and occasionally were accompanied by elastic fibers. Myofibroblasts were regularly present in the valve leaflets. These data show that fasciocutaneous flaps from the scapular region have numerous valves (90 valves on average in each flap) in the venous microcirculation. The microvenous valves in the dorsal thoracic fascia appear to be structurally similar to valves in larger veins. These valves may play a role in the improved hemodynamics and promising clinical outcome of patients with chronic venous insufficiency who have undergone free scapular flap reconstruction.

Fascia↗

PubMed1997

Myxoid tissue: its morphology, histochemistry, and relationship with other supporting tissues.

Myxoid tissue was studied in the supporting organ of the cat epiglottis ("epiglottic cartilage"). Under the light microscope, myxoid tissue was characterized by stellate cells placed into an avascular acidic extracellular matrix. This extracellular matrix was alcianophilic at pH = 2.5, reacting with the colloidal iron stain, and staining metachromatically with toluidine blue O at pH = 5.0. Treatment of sections with testicular hyaluronidase abolished these reactions. In addition, staining persisted after methylation/saponification pretreatment, indicating hyaluronic acid as the main acidic component of myxoid extracellular matrix. Under the electron microscope, myxoid extracellular matrix formed flocculent electron dense precipitates. Stellate myxoid cells were characterized by bundles of intermediate (8 nm) cytoplasmic filaments. Myxoid cells were devoid of a basal lamina, contained a few small lipid droplets, and stored some glycogen. Bundles of collagen fibrils, 80-120 nm in diameter, were seen in myxoid areas. Myxoid cells reacted to S-100 protein, glial fibrillary acidic protein, and neuron specific enolase. Moreover, in adult animals, myxoid cells stained for neurofilament protein 200. All these markers were also present in chondrocytes of elastic and fibrous cartilage, indicating a close relationship between myxoid cells and chondrocytes. This was supported by the observation of continuous transitional forms of myxoid tissue into elastic or fibrous cartilage. In 8-week-old kittens, the supporting organ of the epiglottis was found mainly to consist of myxoid tissue with only a few interspersed islets of chondrocytes. It is therefore concluded that myxoid tissue can serve as a precursor of cartilage.

Adipose Tissue↗

PubMed1997

Localization of endothelin-1 and endothelin-3 in the cochlea.

The distribution of endothelin-1 (ET-1) and endothelin-3 (ET-3) was studied by indirect immunostaining of decalcified guinea pig and rat cochleae. No species differences were observed. Perikarya and processes of spiral ganglion cells were highly reactive for both ET-1 and ET-3. The epithelial lining of the cochlear duct stained for ET-1 and ET-3, but reactivity for ET-1 was higher in the lining cells of the inner sulcus, Claudius', and Hensen's cells, while the tympanic covering layer of the basilar membrane stained stronger for ET-3 compared to ET-1. In the stria vascularis, all cell types stained for ET-3, while marginal cells were more reactive for ET-1. Spiral ligament fibroblasts were reactive for ET-1, but not for ET-3. Connective tissue cells of the spiral limbus stained for both endothelins. The region of synapses on outer hair cells reacted for ET-1 and ET-3 but sensory cells remained unstained. Endothelins are discussed to act as modulatory peptides, possibly interfering with nitric oxide, prostaglandins, and atrial natriuretic peptide in the lateral cochlear wall (lateral cochlear wall, i.e. stria vascularis and spiral ligament). The occurrence of endothelins in cochlear neurons suggest their potential role as neurotransmitters.

Animals↗

PubMed1996

Pulmonary venous sphincters in cattle.

BACKGROUND: The pulmonary veins of rats have regular focal narrowing by tufts of smooth muscle (sphincters) that can contract in response to a variety of stimuli, but these structures are not well studied in other species, and there is little information about their innervation and control. METHODS: The pulmonary veins of 21 cattle were cast with methacrylate, and the casts were studied by scanning electron microscopy, or the fixed tissue was studied by light microscopy with immunocytochemistry and transmission electron microscopy. RESULTS: Constrictions occurred in series along the course of veins (9.6/500 microns), giving the cast veins a string-of-pearl look, with narrowing of 33-81% of the outer diameter. No resin appeared beyond the most narrowed veins. The percentage of contraction did not correlate with the diameter of the veins. With immunohistochemistry using antibodies to S-100, protein gene peptide 9.5, neuron-specific enolase, neurofilament 200, and glial fibrillary acidic protein and with transmission electron microscopy, we could identify no neuronal elements associated with the venous smooth muscle tufts. Bronchial smooth muscle bundles in the same sections stained positively. CONCLUSIONS: The veins of cattle are unlike the rat because the focal venous smooth muscle protrudes deeply into the venous lumen and may completely obstruct perfusion. If the focal venous muscle has no innervation (this study) and can constrict without blood flow (as shown previously), then the venous constriction and, hence, local blood flow regulation must be controlled by local mediators.

Animals↗

PubMed1996

Localization of nitric oxide synthase I and III in the cochlea.

Nitric oxide synthase (NOS) isoforms I and III were localized in the guinea pig cochlea by indirect immunohistochemistry using frozen sections and paraffin sections. NOS I staining was observed in the cytoplasm of outer hair cells, in nerve cell somata and fibers of the spiral ganglion, and in axonal profiles of the spiral lamina next to the base of inner hair cells. In addition, lining cells of the inner sulcus and limbus, and cells of the spiral ligament stained for NOS I but vascular walls remained unstained. NOS III reactivity was seen in the cytoplasm of outer and inner hair cell, in lining cells of the limbus, and on the endolymphatic surface of marginal cells. Staining for NOS III of spiral ganglion perikarya showed varying intensity. Endothelial cells of cochlear glomeruli reacted for NOS III. NOS III in vascular endothelial cells implies regulatory effects of nitric oxide (NO) on vascular wall tonus and cochlear blood supply. NOS I in cochlear neurons indicates these cells as possible sources for NO during neuronal activity. Activated neurons may provide NO that adjusts cochlear perfusion to neuronal activity. Finally, NO that is liberated from hair cells or afferent synaptic terminals may act as an inhibitor on N-methyl-D-aspartate (NMDA) receptors (negative feed-back inhibition).

Animals↗

PubMed1996

Spontaneously hypertensive rats develop pulmonary hypertension and hypertrophy of pulmonary venous sphincters.

This study explored the spontaneously hypertensive rat as an animal model of pulmonary hypertension and sought to identify anatomic changes in its pulmonary microvasculature, especially focal constrictions of pulmonary veins (sphincters). The average systemic and pulmonary artery blood pressures were 172/139 (+/- 9/9) and 36/14 (+/- 4/3), respectively, for spontaneously hypertensive Wistar Kyoto rats (SHR), and 134/83 (+/- 8/2) and 20/10 (+/- 2/2) for normotensive Wistar Kyoto rats (WKY) (P < 0.01 for both). Light microscopy of the lungs in SHR showed muscularization of both arteries and veins, but this was more pronounced in the small pulmonary veins. Perivascular edema was also present. There were 20 (+/- 4) leukocytes per 100 microns of capillary length in SHR and 9 (+/- 2) in WKY (P < 0.001). Transmission electron microscopy showed focal venous smooth muscle was greater in SHR than in WKY. Scanning electron microscopy of vascular casts showed the average maximal focal venous contraction (sphincter) was 54% (+/- 10) of its diameter in SHR, but was only 6% (+/- 4) in WKY (P < 0.01). Arterial contraction occurred in the hypertensive rats as bourglass narrowings of the casts, but was less conspicuous than venous constrictions. The mean alveolar capillary diameter was 8.1 microns (+/- 1.6) in SHR, compared with 6.3 microns (+/- 1.0) in WKY (P < 0.01). The central interspace between capillaries was 3.2 microns (+/- 1.6) in SHR and 6.0 microns (+/- 3.6) in WKY (P < 0.01). The venous contraction, capillary size, and capillary interspace distance correlated with the pulmonary blood pressure. The spontaneously hypertensive rat can be a model of pulmonary hypertension with its most notable structural change being increased muscularity in the small pulmonary veins.

Animals↗