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B Mayer

Publications and source records attributed to B Mayer.

At least 181 records · Page 10Linked to original sources
PubMed1996

Nitrergic and VIPergic neurons in the choroid and ciliary ganglion of the duck Anis carina.

Immunohistochemistry for neuronal nitric oxide synthase (nNOS) and vasoactive intestinal peptide (VIP), and NADPH diaphorase histochemistry, were applied to investigate neurons in the choroid and the ciliary ganglion of the muscovy duck Anis carina. Up to 1000 neurons in the choroid stained for NADPH diaphorase and showed virtually complete colocalization for nNOS immunoreactivity. Almost all of them co-stained for VIP, while about 90% of VIP immunoreactive cell bodies showed colocalization for nNOS. Two-thirds of the neurons were located, mostly singly, at nodes of a wide-meshed nerve plexus in the suprachoroid and were only rarely grouped in ganglia of up to 3 neurons. Numerous varicose nNOS/NADPH-diaphorase-positive nerve fibers were seen around large arterial blood vessels. These fibers derived mainly from paravascular cell bodies that represented about one-third of all choroidal neurons and also displayed costaining for nitrergic markers and VIP. Colocalization of nNOS/NADPH-d and VIP could be demonstrated in most of the perivascular fibers, while slightly more VIP-positive axons in the suprachoroid plexus did not costain for nNOS/NADPH-d. Small-caliber blood vessels and those localized in the choriocapillaris were not endowed with VIP/nNOS/NADPH-diaphorase-positive fibers. A few reactive neuronal cell bodies were also found in ciliary nerves, while most ciliary axons were unstained. In the ciliary ganglion a small subpopulation of neurons showed VIP/nNOS/NADPH-diaphorase colocalization. There were also nNOS/NADPH-d-positive cap-like terminals on ciliary ganglion cells. The presence of VIP/nNOS/NADPH-diaphorase positive neurons and nerve fibers in both the choroid and ciliary ganglion, and in the choroidal perivascular plexus, indicates peripheral nitrergic and VIPergic control of blood flow in the choroid of the duck.

Animals↗
PubMed1996

Nitric oxide synthase in the peripheral nervous system of the goldfish, Carassius auratus.

Neuronal nitric oxide synthase was located in various organs of the goldfish by NADPH-diaphorase histochemistry and immunohistochemistry. Positive cells were detected throughout the digestive tract. A particularly dense plexus of nitric-oxide-synthase-containing fibers was present at the opening of the pneumatic duct into the esophagus and at the intestinal sphincter separating the esophagus and the intestinal bulb. The nitroxergic innervation was mainly confined to the muscularis. The muscular layer of the swim bladder and of the pneumatic duct was densely equipped with stained neurons and fibers. In the heart, the majority of small neurons located at the sinu-atrial junction was found to be positive for nitric oxide synthase. The muscularis of the urinary duct was supplied by fibers originating from many intramural ganglia harboring intensely stained neurons. These results suggest that nitric oxide represents a widespread transmitter in the peripheral nervous system of teleost species.

Animals↗
PubMed1996

Immunohistochemical localization of nitric oxide synthase in rat anterior choroidal artery, stromal blood microvessels, and choroid plexus epithelial cells.

Nitric oxide (NO) has recently been shown to regulate blood flow to choroid plexus, a specialized brain structure responsible for production of most of cerebrospinal fluid. In the present study, we used a specific polyclonal rabbit antibody against the neuronal isoform of NO synthase (NOS), a synthetic enzyme for NO, to determine the localization of NOS in the choroid plexus of adult male Sprague-Dawley rats. NOS-containing nerve fibers were found in the anterior choroidal artery and its branches, and in stromal blood microvessels. Chronic denervation experiments indicated that these nerve fibers originate predominantly from the sphenopalatine ganglion. NOS-immunopositive staining was also detected in the cytoplasm of choroidal epithelial cells. NADPH-diaphorase, a histochemical marker for NOS, was found to colocalize with NOS-immunoreactive product in both nerve fibers and choroidal epithelium. Both neuronal and epithelium-derived NO may regulate secretory function and hemodynamics of choroidal tissue.

Animals↗
PubMed1996

High expression of a Lewis(x)-related epitope in gastric carcinomas indicates metastatic potential and poor prognosis.

BACKGROUND & AIMS: The acquisition of metastatic potential is accompanied by phenotypic changes. The aim of this study was to identify those changes that may lead to the development of new antimetastatic strategies in gastric cancer. METHODS: A new murine monoclonal antibody showing differential reactivity with benign and malignant gastric tissues was isolated. The expression pattern of the recognized 2B4 antigen was determined with immunohistochemistry, and the antigen was analyzed by immunoprecipitation and enzyme digestion. Its prognostic impact in gastric cancer was tested in univariate and multivariate analyses. RESULTS: In gastric mucosa, 2B4 expression was significantly reduced on mucosal glands in the presence of an inflammatory infiltrate and could be modulated in vitro by exposure to interferon alfa and gamma and phorbol esters. Twenty-eight percent of the primary gastric carcinomas showed high levels of 2B4. This correlated significantly with clinicopathological parameters of advanced disease (tumor size of > 50 mm, M1 stage, and UICC stage IIIB/IV). In multivariate analysis, high 2B4 expression was found to be a new, independent parameter of poor prognosis. The 2B4 monoclonal antibody was shown to react with the trisaccharide Gal beta 1-->4(Fuc alpha 1-->3)GlcNAc, i.e., Lewis(x). CONCLUSIONS: High levels of the Lewis(x)-related epitope defined by MAb 2B4 in primary gastric carcinomas is an independent parameter of poor survival.

Animals↗
PubMed1996

[Free microsurgical superior musculocutaneous trapezius flap of the swine: an ideal training model for microvascular reconstructions and in vitro model for experimental microsurgery].

BACKGROUND: Until now there have been no published studies on musculocutaneous porcine free flaps with an uncompromised vascular pedicle, easy surgical access and anatomic orientation allowing unlimited postoperative movement, as German animal research regulations require. RESULTS: The authors present the porcine musculocutaneous superior trapezius flap. It is supplied by the transverse neck artery, a branch of the thyrocervical trunk of the subclavian artery as in human anatomy. CONCLUSION: The advantages of this flap are its easy surgical access, its uncompromised vascular anatomy, and the easy closure of the donor area. The authors demonstrated the uncompromised vascular anatomy in 40 pigs with body weights ranging between 24 and 68 kg. The pigs were able to move normally following surgery.

Animals↗
PubMed1996

[Current systematic definition and terminology of the face lifting technique].

OBJECTIVE: A more precise definition of the term "face lifting" appears to be necessary. The development of new techniques and modifications in the last decade has been the main reason for the proliferation of definitions. Nearly every author has his own terminology for describing his procedures. METHODS: Three criteria are helpful in achieving an overview. 1. The selection according to the anatomical areas of the face and the neck which have to be rejuvenated 2. The selection according to procedures, involving resection of soft tissues as opposed to techniques that solely involve soft tissue reposition, modification of facial bones, and combinations of these principles. 3. The selection according to the different layers of soft tissue or to the combination of different layers which are to be lifted. CONCLUSIONS: The terms "face lifting" and "lifting" are used synonymously in international literature. They refer to those surgical procedures which aim a achieve facial rejuvenation and a younger appearance of the neck. Definitions that refer only to a lifting of the facial skin do not correspond to the actual techniques, which often involve the surgical treatment of different soft tissue layers and sometimes facial bone. A classification is possible because some terms are used more often.

Humans↗
PubMed1996

[The SMAS (subcutaneous musculo-aponeurosis system) flap: a possibility for filling out soft tissue defects after parotidectomy].

BACKGROUND: Parotidectomies sometimes leave a conspicuous soft-tissue defect in the dorsal part of the cheek. METHODS: The authors present a modification of the standard technique of parotidectomy which is reserved for the surgical management of benign parotid tumors. The incision of the skin follows the guidelines for standard subcutaneous rhytidectomy with a modification according to the Redon incision. They use flaps of the subcutaneous musculoaponeurotic system (SMAS), which they fold or rotate in order to fill the soft-tissue defect following parotidectomy. The preparation of the skin and the SMAS in layers from the lateral to the medial aspect of the cheek does not affect the blood supply which comes from medially running vessels. RESULTS: Forty patients have been operated on using these modifications of the standard technique. A postoperative follow-up of more than one year could be controlled in 31 cases. Thirty patients showed an inconspicuous dorsal region of the cheek without a soft-tissue defect compared to the other side. They did not wish a secondary operation for an aesthetic improvement except two scar revisions. CONCLUSION: To date this surgical concept has proved its worth.

Esthetics↗
PubMed1996

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Journal Article↗
PubMed1996

Inhibition of nitric oxide synthesis by NG-nitro-L-arginine methyl ester (L-NAME): requirement for bioactivation to the free acid, NG-nitro-L-arginine.

1. The L-arginine derivatives NG-nitro-L-arginine (L-NOARG) and NG-nitro-L-arginine methyl ester (L-NAME) have been widely used to inhibit constitutive NO synthase (NOS) in different biological systems. This work was carried out to investigate whether L-NAME is a direct inhibitor of NOS or requires preceding hydrolytic bioactivation to L-NOARG for inhibition of the enzyme. 2. A bolus of L-NAME and L-NOARG (0.25 micromol) increased coronary perfusion pressure of rat isolated hearts to the same extent (21 +/- 0.8 mmHg; n = 5), but the effect developed more rapidly following addition of L-NOARG than L-NAME (mean half-time: 0.7 vs 4.2 min). The time-dependent onset of the inhibitory effect of L-NAME was paralleled by the appearance of L-NOARG in the coronary effluent. 3. Freshly dissolved L-NAME was a 50 fold less potent inhibitor of purified brain NOS (mean IC50 = 70 microM) than L-NOARG (IC50 = 1.4 microM), but the apparent inhibitory potency of L-NAME approached that of L-NOARG upon prolonged incubation at neutral or alkaline pH. H.p.l.c. analyses revealed that NOS inhibition by L-NAME closely correlated with hydrolysis of the drug to L-NOARG. 4. Freshly dissolved L-NAME contained 2% of L-NOARG and was hydrolyzed with a half-life of 365 +/- 11.2 min in buffer (pH 7.4), 207 +/- 1.7 min in human plasma, and 29 +/- 2.2 min in whole blood (n = 3 in each case). When L-NAME was preincubated in plasma or buffer, inhibition of NOS was proportional to formation of L-NOARG, but in blood the inhibition was much less than expected from the rates of L-NAME hydrolysis. This was explained by accumulation of L-NOARG in blood cells. 5. These results suggest that L-NAME represents a prodrug lacking NOS inhibitory activity unless it is hydrolyzed to L-NOARG. Bioactivation of L-NAME proceeds at moderate rates in physiological buffers, but is markedly accelerated in tissues such as blood or vascular endothelium.

Animals↗
PubMed1996

Neurochemical characterization of intrinsic neurons in ferret tracheal plexus.

Although neuroanatomical and neurophysiological features of neurons in the ferret trachea have been studied, the neural mediators associated with this plexus have not been completely characterized. The purpose of this study was to examine the occurrence of choline acetyltransferase (ChAT), nitric oxide synthase (NOS), vasoactive intestinal peptide (VIP), and substance P(SP) in the intrinsic neurons of this plexus. The distribution of double- and triple-labeled neurons was quantified in cryostat sections and in whole mounted specimens to evaluate the neurochemical profiles. About 85% of the nerve cell bodies with ChAT immunoreactivity (ChAT-IR) were located in ganglia of the longitudinal trunks or the closely associated bridge ganglia. Approximately 15% of ChAT-positive neurons were in ganglia of the superficial muscular plexus. Conversely, VIP-IR neurons were most frequent in the superficial muscular plexus (>75%) and, <10% were observed in the longitudinal trunks or bridge neurons. Most NOS- and SP-IR neurons were also located in the superficial muscular plexus. The following distribution of neurochemical profiles was determined for neurons of the superficial muscular plexus: 11% only NOS, 20% only VIP, 5% only SP, 67% NOS and VIP, and 40% VIP and SP. NOS, VIP, and SP were frequently localized in the same nerve cell body. The occurrence of nerve terminals containing only SP located around the borders of individual NOS/VIP/SP-containing neurons suggests possible sensory innervation to the airway neurons. The results demonstrate that: (1) most cholinergic nerves do not contain VIP, NOS, or SP; (2) cholinergic neurons are predominantly located in the longitudinal trunk ganglia; (3) VIP, NOS, and SP are predominantly located in the superficial muscular plexus ganglia; and (4) nerve terminals containing exclusively SP, suggesting possible sensory origin, are closely associated with some neurons in the plexus.

Animals↗
PubMed1996

Novel guanylyl cyclase inhibitor potently inhibits cyclic GMP accumulation in endothelial cells and relaxation of bovine pulmonary artery.

The aim of the present study was: 1) to determine the effects of the novel selective inhibitor of guanylyl cyclase, ODQ (1H-[1,2,4]oxadiazolo[4,3,-a]quinoxaline-1-one) on basal and agonist-stimulated cyclic GMP levels in cultured porcine aortic endothelial cells and bovine pulmonary artery strips; 2) to determine its effects on agonist-induced relaxations of bovine pulmonary artery strips; and 3) to compare pulmonary artery cyclic GMP levels with vessel relaxation. ODQ (1 nM-30 microM) inhibited cyclic GMP accumulation in endothelial cells stimulated with S-nitrosoglutathione, nitroprusside and 3-morpholine-sydnonimine at IC50 values of 40 to 100 nM. Complete suppression of cyclic GMP generation was observed at approximately 10 microM. Relaxation of pulmonary artery strips induced by S-nitrosoglutathione, nitroprusside, glycerol trinitrate, nitrite (all endothelium-independent), bradykinin and the Ca++ ionophore A23187 (endothelium-dependent) were antagonized by ODQ (1-10 microM) in a concentration-dependent way. A consistent feature of the inhibitor was that maximal relaxant effects also were reduced. Basal levels and agonist-induced increases in arterial tissue cyclic GMP were inhibited in the same concentration range. However, tissue cyclic GMP production correlated poorly with pulmonary artery relaxation in that relaxations induced by S-nitrosoglutathione were only inhibited in part (50%), whereas rises in cyclic GMP were abolished completely by ODQ (10 microM). Furthermore, at 1 microM, ODQ had no effect on relaxation induced by endothelium-dependent agonists, but prevented entirely stimulation of cyclic GMP accumulation in arterial tissue. These results suggest that ODQ inhibits nitrovasodilator-induced and endothelium-dependent relaxation through inhibition of guanylyl cyclase activation, but also point to the presence of a cyclic GMP-independent component of relaxation in bovine pulmonary artery.

Animals↗
PubMed1996

Demonstration of NADPH-diaphorase (NO-synthase) in sebaceous glands of the mammalian integument, with remarks on the glandular capillary net.

The study demonstrates weakly to strongly positive reaction staining for NADPH-diaphorase/NO- synthase in the peripheral cells of sebaceous glands in the hairy skin of domesticated mammals. Additionally, the structure of the blood capillary system surrounding these glands is better elucidated. The results obtained are discussed in view of a modulatory action of NO generated by these enzyme activities, implying a direct influence of this substance on the contractile elements of gland-associated blood capillaries. In this way, a simple and self-regulatory mechanism to couple blood flow and glandular metabolism can be proposed.

Animals↗
PubMed1996

Characterization of 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one as a heme-site inhibitor of nitric oxide-sensitive guanylyl cyclase.

Nitric oxide (NO) binds with high affinity to the heme of soluble guanylyl cyclase (sGC), resulting in accumulation of the second messenger cGMP in many biological systems. 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) was recently described as potent and selective inhibitor of sGC, providing an invaluable tool with which to settle the function of the cGMP pathway in NO-mediated signal transduction [Mol. Pharmacol. 48:184-188 (1995)]. The present study investigated the mechanism of ODQ-induced inhibition of purified bovine lung sGC. The drug induced a rightward shift of the concentration-response curves recorded with two different NO donors and a reduction of maximal sGC activity, pointing to a mixed type of inhibition. The time course of NO-stimulated sGC activity determined in the presence of 0.3 microM ODQ showed that the inhibitory effect was time-dependent (half-time approximately 3 min) and virtually complete after about 10 min. The cyclase did not recover from ODQ-induced inhibition upon extensive dilution, pointing to an apparently irreversible inactivation of the enzyme by the quinoxalin. Light absorbance spectroscopy showed that ODQ (0.3 mM) induced a shift of the Soret band of the heme from 431 nm to 393 nm, indicating that ODQ oxidizes the ferrous form of the enzyme to the ferric species, which is though to exhibit only poor NO sensitivity. Together, our results suggest that inhibition of sGC by ODQ is NO-competitive and results in an apparently irreversible oxidation of the prosthetic heme group.

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