Slight Constriction Research Articles

Avaliação oftalmológica em pacientes com AIDS e neurotoxoplasmose

To describe fundoscopic findings among patients with AIDS and active-phase neurotoxoplasmosis. A prospective study of case series type was developed, including 70 patients of both sexes and ages ranging from 20 to 63 years who were admitted to the wards of three public hospitals in the city of Recife, Pernambuco, Brazil, from January to October 2008, with diagnoses of AIDS and neurotoxoplasmosis determined according to the criteria of the Centers for Disease Control and Prevention (1992). The patients were characterized by a first episode of neurotoxoplasmosis (65; 92.9%) or recurrence (5; 7.1%), unawareness of having AIDS (23; 32.9%), mean T CD4+ count of 139.8 + or - 3.04 lymphocytes/mm(3) and mean viral load of 137,080 + or - 39,380 copies/ml. All patients underwent ophthalmological examination consisting of ocular inspection, gauging of visual acuity, investigation of ocular extrinsic muscle function and fundoscopy using a binocular indirect ophthalmoscope (model OHM 3.5 Eyetec) and external lens of 20 diopters (Volk). The findings consisted of retinal cotton-wool spot exudates (8.6%), slight diffuse arteriolar constriction (8.6%), retinochoroiditis scars characteristic of ocular toxoplasmosis (5.7%), atrophy of retinal pigment epithelium (2.9%), retinal detachment (2.9%), increased papillary excavation (1.4%), retinal peripheral degeneration (1,4%), macroaneurysm (1.4%), bilateral papilledema (1.4%) and vitreous-retinal traction (1.4%). Patients with AIDS and neurotoxoplasmosis may present fundoscopic abnormalities characteristic of ocular toxoplasmosis, either in active or in scar form, related to HIV or even to other opportunist or systemic diseases, which can be of great aid for integral treatment of patients by a multiprofessional team.

First Report of Damping-Off Caused by Rhizoctonia solani AG-4 on Mediterranean Fan Palm in Italy.

Mediterranean fan palm (Chamaerops humilis L.), one of just two autochthonous European palms, is native to the western Mediterranean Region in southwestern Europe and northwestern Africa. It can be found growing wild in the Mediterranean area. In Europe, this species is very popular as an ornamental plant. In March 2009, a widespread damping-off was observed in a stock of approximately 30,000 potted 1-month-old plants of C. humilis cv. Vulcano in a nursery in eastern Sicily. Disease incidence was approximately 20%. Disease symptoms consisted of lesions at the seedling shoot (plumule). Stem lesions were initially orange, turned brown, and followed by death of the entire plumule or eophyll. A fungus with mycelial and morphological characteristics of Rhizoctonia solani Kühn was consistently isolated from lesions when plated on potato dextrose agar (PDA) amended with streptomycin sulfate at 100 μg/ml. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia. Mycelium was branched at right angles with a septum near the branch and a slight constriction at the branch base. Hyphal cells removed from cultures grown at 25°C on 2% water agar were determined to be multinucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates with tester strains AG-1 IA, AG-2-2-1, AG-2-2IIIB, AG-2-2IV, AG-3, AG-4, AG-5, AG-6, and AG-11 on 2% water agar in petri plates (3). Anastomosis was observed only with tester isolates of AG-4, giving both C2 and C3 reactions (2). One representative isolate obtained from symptomatic tissues was deposited at the Fungal Biodiversity Centre, Centraalbureau voor Schimmelcultures (CBS No. 125095). Pathogenicity tests were performed on container-grown, healthy, 1-month-old seedlings. Twenty plants of C. humilis cv. Vulcano were inoculated near the base of the stem with two 1-cm2 PDA plugs from 5-day-old mycelial cultures. The same number of plants served as uninoculated controls. Plants were incubated in a growth chamber and maintained at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Symptoms identical to those observed in the nursery appeared 5 days after inoculation and all plants died within 20 days. No disease was observed on control plants. A fungus identical in culture morphology to R. solani AG-4 was consistently reisolated from symptomatic tissues, confirming its pathogenicity. To our knowledge, this is the first report in the world of R. solani causing damping-off on Mediterranean fan palm.

Ultrastructure of male accessory glands of Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae)

The ultrastructure of the male accessory glands of the blow fly, Chrysomya megacephala (Fabricius), was presented using light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A pair of accessory glands was separated at opposite sites. Morphometric results using LM yield evidenced no significant difference in the median of either length or width of the left and right glands. A significant increment in both length and width was seen to plateau between three to six days. SEM observation showed that the surface of the glands revealed a faint irregular groove pattern throughout, and it was occasionally penetrated by tracheoles. Each gland was a slender, elongated sac-like tubule having apical rounded ends, with a slight constriction at the sub-apical part of the gland being observed occasionally. TEM analyses of three-day-old males showed that the glands consisted of external capsular cells with a basement membrane underneath, glandular cells, and gland lumen. The capsular cell was flat and contained a nucleus with electron dense material in the nuclear envelope. The glandular cell, appearing as columnar, consisted of a vacuolated component that contained a large oval nucleus centrally or sub-basally located, with dense mitochondria, numerous rough endoplasmic reticulum, and secretory vesicles containing electron-lucent materials. In the gland lumen, the cross-section through the middle portion revealed dense secretory materials, characterized by electron-dense materials. Some sections revealed a large lumen where secretion accumulates within the delicate sac. The seven-day-old glands exhibited a remarkable change in the lumen, where the whole space contained a large amount of secretory materials, with the electron-dense materials being characterized as similar to those observed in three-day-old glands. About four prominent types of secretions were observed on the basis of difference in electron-density.

First Report of Crown and Root Rot Caused by Rhizoctonia solani AG-4 on Coprosma repens and C. lucida in Italy.

Coprosma (J.R. Forster & G. Forster), a genus containing approximately 90 species, occurs principally in New Zealand, Hawaii, Australia, New Guinea, and islands of the Pacific. In Italy, some of these species, including many variegated varieties and hybrids, are grown as ornamental evergreen shrubs or small trees. In June 2008, a crown and root rot was observed in a stock of approximately 12,000 potted 3-year-old plants of Coprosma repens cv. Yvonne and C. lucida in a nursery in eastern Sicily. Disease incidence was approximately 30%. Disease symptoms consisted of water-soaked lesions at the crown of the trunk and a root rot. Successively, older stem lesions turned orange to brown. As a consequence, leaves initially became chlorotic, gradually became necrotic, and death of the plant followed. A fungus with mycelial and morphological characteristics of Rhizoctonia solani Kühn was consistently isolated from crown and root lesions when plated on potato dextrose agar (PDA) amended with streptomycin sulfate at 100 μg/ml. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia. Mycelium was branched at right angles with a septum near the branch and a slight constriction at the branch base. Hyphal cells removed from cultures grown at 25°C on 2% water agar were determined to be multinucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates on 2% water agar in petri plates (3). Pairings were made with tester strains of AG-1 IA, AG-2-2-1, AG-2-2IIIB, AG-2-2IV, AG-3, AG-4, AG-5, AG-6, and AG-11. Anastomosis was observed only with tester isolates of AG-4, giving C2 and C3 reactions (2). Two representative isolates obtained from symptomatic tissues of C. lucida and C. repens cv. Yvonne were deposited at the Fungal Biodiversity Centre, Centraalbureau voor Schimmelcultures (DISTEF CL1 = CBS-124593 and DISTEF CR1 = CBS-124594, respectively). Pathogenicity tests were performed on container-grown, healthy, 3-month-old cuttings. Ten plants of C. lucida and ten plants of C. repens cv. Yvonne were inoculated near the base of the stem with five 1-cm2 PDA plugs from 5-day-old mycelial cultures. The same number of plants served as uninoculated controls. Plants were maintained at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Symptoms identical to ones observed in the nursery appeared 5 days after inoculation and all plants died within 15 days. No disease was observed on control plants. A fungus identical in culture morphology to R. solani AG-4 was consistently reisolated from symptomatic tissues, confirming its pathogenicity. To our knowledge, this is the first report of R. solani causing crown and root rot on the genus Coprosma.

Response to reply to the letter to the editor concerning “Gebauer et al.: Subdental synchondrosis and anatomy of the axis in aging: a histomorphometric study on 30 autopsy cases. Eur Spine J 15(3):292–298, 2006”: The basis of the dens axis. Where is it located?

Response to reply to the letter to the editor concerning “Gebauer et al.: Subdental synchondrosis and anatomy of the axis in aging: a histomorphometric study on 30 autopsy cases. Eur Spine J 15(3):292–298, 2006”: The basis of the dens axis. Where is it located?

Effect of Diode Laser Retinal Ablative Therapy for Threshold Retinopathy of Prematurity on the Visual Field: Results of Goldmann Perimetry at a Mean Age of 11 Years

To assess the peripheral visual field in premature children who received diode laser photocoagulation for threshold retinopathy of prematurity (ROP) and in a comparison group with subthreshold ROP that had regressed spontaneously without laser treatment. Eleven patients (18 eyes) were treated with laser, and nine patients (16 eyes) with subthreshold untreated ROP were recalled for assessment at a mean follow-up of 11 years. All children underwent Goldmann visual field testing using the II4e and V4e stimuli. Distance visual acuity measurement, dilated fundal examination, and cycloplegic autorefraction were also performed. The visual field extent in treated eyes was 3% to 4% smaller for the V4e target and 7% to 10% smaller for the II4e target than in the comparison eyes. For the II4e stimulus, the right eye visual field extent of the laser-treated children did not differ significantly from that of the untreated comparison group (P = .11), but the left eyes showed a borderline significant reduction (P = .046). For the larger V4e stimulus, no significant differences were noted (right eye, P = .41; left eye, P = .30). This is the first study to assess the effect of diode laser therapy on the peripheral visual field in eyes with threshold ROP using Goldmann perimetry. Laser-treated eyes showed a slight constriction of peripheral visual fields compared with untreated subthreshold eyes. It is uncertain whether this was due to the laser treatment itself or to the more severe ROP in the laser group. However, the limited reduction in visual field extent is comparable to that reported for cryotherapy and is unlikely to be of functional significance.

Puccinia acroptili on Russian Knapweed in Colorado, Montana, and Wyoming.

Acroptilon repens (L.) DC. (Russian knapweed) is a long-lived perennial weed from central Asia that is widely distributed in the western United States (U.S.). Recently, accessions of a rust disease were collected from Colorado (CO), Montana (MT), and Wyoming (WY) for comparison with Eurasian isolates. U.S. accessions had two-celled teliospores with slight constrictions in the middle and urediniospores with three germ pores ± equatorial in location. Urediniospores were (state, width × length, [n = 100]): CO, 16.4 to 25.7 × 19.2 to 27.0 μm; MT, 18.4 to 23.1 × 17.4 to 24.6 μm; and WY, 18.0 to 26.2 × 20.2 to 26.7 μm. These were similar to those of 16.6 to 25.7 × 21.2 to 28.0 μm from two New Mexican (NM) herbarium specimens (BPI Nos. 1107952 and 1110177) (1). Teliospores measured 19.9 to 27.7 × 29.8 to 47.4 μm, 17.4 to 26.0 × 32.4 to 44.2 μm, 16.5 to 27.5 × 29.4 to 45.7 μm, and 18.7 to 27.6 × 31.0 to 46.4 μm for CO, MT, WY, and NM accessions, respectively. These rust isolates have been identified as Puccinia acroptili Syd. on the basis of host plant record and spore morphology (2). To our knowledge, this is the first record of P. acroptili in CO, MT, and WY. Besides NM, P. acroptili has been reported in North America from California, British Columbia, and Saskatchewan.

Contribution of hemodynamics and light scattering to the changes in optical intrinsic signal during cortical spreading depression in rats

Optical intrinsic signals (OIS) imaging has been shown a powerful method for characterizing the spatial and temporal pattern of the propagation of cortical spreading depression (CSD) with high resolution. However, the possible physiological mechanisms underlying these OIS during CSD still remain incompletely understood. In this study, spectroscopic recording of the changes in OIS during pinprick induced CSD were performed at the exposed cortex of -chloralose/urethane anesthetized Sprague-Dawley rats (male, n=12) using a fiber optic reflectance spectrometer (PC-1000, Ocean Optics Inc.) to estimate the contribution of hemodynamics and light scattering to the changes in OIS. The fiber probe (source-detector fiber separation: 0.2 mm) was placed at cortical parenchyma site avoiding large blood vessels. For each animal, five CSDs were elicited with an interval of half an hour. On each CSD induction, the spectra data was collected over a 400 seconds period at the rate of 2 Hz. The changes in the concentration of HbO2 and Hb, and changes in light scattering was estimated by fitting the experimental reflectance spectra data to a modified Beer-Lambert equation using a linear least squares fitting procedure, for a spectral range of 460630 nm. The fit was good with a residual error less than 5% in most experiments. In this experiment, four-phasic changes in OIS were observed at 460 nm 570 nm, but triphasic changes were observed at longer wavelength. The fitting results showed that the CSD induced an initial increase in concentration of HbO2 (amplitude: 9.03.7%), which was 26.218.6 s earlier than the onset of increase of Hb concentration. The increase in concentration of Hb reached its maximum value 47.25.9 s earlier than that of HbO2. Whereas the concentration of HbO2 showed a four-phasic change, the light scattering showed a triphasic change and the concentration of Hb only showed a biphasic change. The timing relationship between OIS and concentration of HbO2 and Hb indicated that the initial phase of the decreased IOS at 550 nm was only caused by the concentration increase of oxygenated hemoglobin at cortical parenchyma sites. But during the second phase of the increased optical reflectance at 550 nm, more complicated physiological mechanisms may be involved, not only the changes in concentration of HbO2, Hb and Hbt, but also the changes in light scattering contributed significantly to the increase of optical reflectance. When the concentration of HbO2 shows a small decrease (7.84.5%), the concentration of Hb increased 24.510.8%, simultaneously with a significant increase of light scattering. Interestingly, in our previous studies, a slight constriction of the pial arteries was observed during this phase of OIS. The constriction of the pial artery and the increase of concentration of total hemoglobin at cortical parenchyma site suggest that the regulations of the pial artery and capillary during this phase may be controlled by different mechanisms. During the followed third phase of light decrease at 550 nm, an increase of blood volume (concentration of total hemoglobin), an increase of oxygenation and decrease of scattering all contributed to the change of intrinsic optical signal.

Structural basis for preferential binding of non-ortho-substituted polychlorinated biphenyls by the monoclonal antibody S2B1

Polychlorinated biphenyls (PCBs) are a family of 209 isomers (congeners) with a wide range of toxic effects. In structural terms, they are of two types: those with and those without chlorines at the ortho positions (2, 2', 6 and 6'). Only 20 congeners have no ortho chlorines. Three of these are bound by the aryl hydrocarbon receptor and are one to four orders of magnitude more toxic than all others. A monoclonal antibody, S2B1, and its recombinant Fab have high selectivity and nanomolar binding affinities for two of the most toxic non-ortho-chlorinated PCBs, 3,4,3',4'-tetrachlorobiphenyl and 3,4,3',4',5'-pentachlorobiphenyl. To investigate the basis for these properties, we built a three-dimensional structure model of the S2B1 variable fragment (Fv) based on the high-resolution crystallographic structures of antibodies 48G7 and N1G9. Two plausible conformations for the complementarity-determining region (CDR) H3 loop led to two putative PCB-binding pockets with very different shapes (models A and B). Docking studies using molecular mechanics and potentials of mean force (PMF) indicated that model B was most consistent with the selectivity observed for S2B1 in competition ELISAs. The binding site in model B had a deep, narrow pocket between V(L) and V(H), with a slight constriction at the top that opened into a wider pocket between CDRs H1 and H3 on the antibody surface. This binding site resembles those of esterolytic antibodies that bind haptens with phenyl rings. One phenyl ring of the PCB fits into the deep pocket, and the other ring is bound in the shallower one. The bound PCB is surrounded by the side chains of TyrL91, TyrL96 and TrpH98, and it has a pi-cation interaction with ArgL46. The tight fit of the binding pocket around the ortho positions of the bound PCBs indicates that steric hindrance of ortho chlorines in the binding site, rather than induced conformational change of the PCBs, is responsible for the selectivity of S2B1.

First Report of Sharp Eyespot of Wheat in Egypt.

In 1998 and 1999, Rhizoctonia solani Kühn and R. cerealis van der Hoeven were isolated from lesions on basal leaf sheaths (2 to 4 cm above the soil level) of 48 wheat plants (Triticum aestivum L. em. Thell.). Plants were collected from 16 locations in Egypt in December 1998 (seedling stage) and March 1999 (adult stage). Disease incidence was approximately 20 and 30% during the 1998 to 1999 and 1999 to 2000 seasons, respectively. Mycelium was white to deep brown, branched at right angles with a septum near the branch, and a slight constriction at the branch base. Multinucleate cells and the production of irregular, brown black sclerotia in culture and on host plants were diagnostic of R. solani (1). Anastomosis groups AG-4 (30 isolates) and AG-1 (6 isolates) of R. solani, distinguished on the basis of hyphal fusion, were recovered. R. cerealis (12 isolates belonging to the anastomosis group CAG-1), which were slow-growing on potato dextrose agar, produced binucleate hyphal cells and yellow sclerotia. The 48 isolates were tested in the greenhouse for pathogenicity using cornmeal and sand inoculum prepared by mixing 3 g of infested cornmeal, 100 g of sand, and 20 ml of distilled water and incubating for 20 days at 28°C. Fifty milliliters of inoculum were added to 500 g of sterile soil in a 15-cm-diameter pot. There were six pots per isolate. Six pots containing noninfested soil were included as checks. Wheat (cv. Giza 160) seeds were disinfested by placing them in 5% of sodium hypochlorite for 5 min, and 10 seeds were planted in each pot. Twenty-five days after planting, an average of five plants survived in the pots treated with R. solani, and seven plants survived in pots treated with R. cerealis. All 10 plants in the noninfested pots survived and were symptomless. The surviving plants treated with R. solani developed a tan cortical rot of the root system and tan zonate lesions on the basal leaf sheaths. The lesions were oriented longitudinally with the stem and were irregular in shape with a white or light tan center surrounded by a wide, dark brown margin. Isolates of R. cerelis caused lesions on the base of the stem of young and mature plants. The lesions, which were larger than those caused by R. solani, were elliptic or "eye" shaped with a pale yellow center and sharply defined narrow border. The fungi were reisolated from the symptomatic tissue. Reference: (1) J. D. S. Clarkson and M. J. Griffin. Plant Pathol. 26:98, 1977.

Formation of propagules on an invasive strain of Caulerpa racemosa (Chlorophyta) in the Mediterranean Sea

An invasive strain of Caulerpa racemosa has been spreading rapidly in the Mediterranean Sea since 1990. It reproduces itself sexually or by random fragmentation of the thallus. We report a new way of vegetative reproduction: a specific fragmentation process involving detachment of ramuli. The ramuli of the invasive strain of C. racemosa are cylindrical to clavate, with a rounded apex and a slight constriction at their insertion on the rachis of the frond. They detach themselves from the fronds and form fine coenocytic chlorophyllous filaments. The production of these propagules may explain the regeneration of C. racemosa meadows, which disappear in certain regions during winter, and may also account for the rapid dissemination of the alga.

A New Foliar Blight of Douglas-fir, Grand Fir, and Noble Fir Caused by a Binucleate Rhizoctonia-like Fungus.

The Oregon State University Plant Clinic received samples in 1996 and 1997 of Douglas-fir (Pseudotsuga menziesii) with web blight from Christmas tree plantations in Douglas, Lane, and Benton counties. Affected needles were 1 or more years old, uniformly brown, with no chlorosis or banding, and had a tendency to hang down from the branches and cling together, bound by mycelial webbing visible at ×10 magnification. In 1998, the disease was found on grand (Abies grandis) and noble (A. procera) firs in Christmas tree plantations as well as in native stands of Douglas-fir. Twigs of grand fir were killed, but not those of Douglas-fir. Brown needles may encompass half the side of a tree, destroying its value. This disease has been severe in Christmas tree plantations. A binucleate Rhizoctonia-like species has been consistently isolated from affected needles from all three tree species. The fungus has hyphae averaging 6.0 μm in diameter, with dolipore septa, slight constriction at the branch points, and acute to right angle branching. No sclerotia are formed, but monilioid cells develop after 2 weeks. Cell nucleation was determined with cotton blue or ethidium bromide. Koch's postulates were fulfilled by inoculating with an isolate obtained from grand fir onto 2-year-old Douglas-fir trees. Plugs (7 mm in diameter) of mycelium growing on potato dextrose agar plates were removed and placed onto the foliage of three trees. Plugs from uninoculated plates were used as a control on three additional trees. Inoculated trees were placed under mist on a greenhouse bench. Symptomatic needles were observed 5 weeks after inoculation. A fungus identical to the inoculum was obtained from symptomatic needles. No Rhizoctonia-like fungi were obtained from needles of the control plants. Further characterization of the fungus is underway. This new disease of Douglas-fir and true firs is potentially devastating, since Douglas-fir is a major component of managed timber forests in western Oregon, and the disease has been found at numerous sites in timber trees in the region.

Role of the nitric oxide-cGMP system in the regulation of ductus arteriosus patency in fetal rats.

The purpose of this study was to examine the role of the nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) system in the regulation of the ductus arteriosus (DA) patency in fetal rats. Pregnant rats were administered N(G)-nitro-L-arginine methyl ester (L-NAME, 50 mg/kg, ip), an NO synthase (NOS) inhibitor; methylene blue (30, 50 and 100 mg/kg, ip), a soluble guanylate cyclase inhibitor; or indomethacin (3 mg/kg, po), a cyclooxygenase inhibitor, at various times before cesarean section. Dams were decapitated to obtain the fetuses by cesarean section, and fetuses were rapidly frozen in an acetone-dry ice mixture. Using rapid freezing and shaving methods, the calibers of the DA, pulmonary artery (PA) and descending aorta (Ao) were measured to evaluate the effects of treatment. L-NAME reduced the DA calibers to 86% of the initial values, but recovery to the control levels occurred 6 hr after the injection. Indomethacin decreased the DA calibers to 34% of the control values and sustained the DA constriction until 24 hr after the treatment. Methylene blue caused DA constriction to almost the same degree as indomethacin, but the levels normalized within 24 hr after the treatment. We conclude that L-NAME caused a slight constriction of the DA, whereas methylene blue and indomethacin caused marked constriction of the vessels, suggesting that the NO-cGMP system as well as prostaglandins contribute to the DA patency.

Comparison of the myogenic response in rat cerebral arteries of different calibers

The myogenic response, the characteristic of blood vessels to contract with increasing pressure, was studied at three different locations along the middle cerebral artery (MCA) vascular tree. We hypothesized that smaller caliber vessels would have a more pronounced myogenic response at lower pressures than larger diameter arteries, corresponding to pressures normally experienced in vivo. Cerebral vessels (MCAs, branches of the MCA, and penetrating arterioles) were isolated from male rats, cannulated with glass micropipettes, and pressurized. Changes in diameter were measured as the transmural pressure was increased from 20–100 mmHg. The MCAs, which had a resting diameter of 202±10 μm ( n=9) at 50 mmHg, showed its greatest myogenic response between 60–100 mmHg (8±2% constriction, n=9, p<0.001). The penetrating arterioles [58±4 μm ( n=8) at 50 mmHg], on the other hand, showed its greatest myogenic response between 20–60 mmHg (10±4% constriction, n=8, p<0.05). Branches of the MCA [118±14 μm ( n=8) at 50 mmHg] showed a slight constriction over the entire pressure range (5±9% constriction between 20–100 mmHg, p=ns). Our results suggest that the myogenic response appears to be best developed in the range of pressures found during physiological conditions for a given vessel in the MCA territory. This characteristic is fundamental in the overall control of cerebrovascular resistance.

Microtubule and actin filament organization during stomatal morphogenesis in the fernAsplenium nidus

The newly-formed guard cell mother cells (GMCs) ofAsplenium nidus are small, lens-shaped and are formed by one or two asymmetrical divisions. Their growth axis is parallel to the plane of their future division, a process during which the internal periclinal wall (IPW) is detached from the partner wall of the underlying cell(s). This oriented GMC expansion occurs transversely to a microfibril bundle, which is deposited externally to a U-like microtubule (Mt) bundle and a co-localized actin filament (Af) bundle. They line the IPW and the major part of the anticlinal walls. The deposition of the microfibril bundle is followed by the slight constriction of the internal part of the GMCs and the broadening of the substomatal cavity. The IPW forms a distinct bulging distal to the neighbouring leaf margin, as well as a less defined proximal one. During the IPW bulging, the Mts and Afs under the external periclinal wall (EPW) attain a radial organization. This is followed by thinning of the central EPW region, which becomes impregnated with a callose-like glucan. The rest of the EPW becomes unequally thickened. The disintegration of the U-like Mt bundle is succeeded by the organization of radial Mt and Af arrays under the IPW. The radial Mt systems, controlling the alignment of the newly-deposited microfibrils, allow the GMC to assume a round paradermal profile. The GMCs form a preprophase Mt band (PPB) perpendicular to the interphase U-like Mt bundle. The anticlinal PPB portions appear first and those lining the periclinal walls later. The cytoplasm adjacent to the latter walls retain the radial Mt systems during early preprophase, simultaneously with the anticlinal PPB portions. The observations suggest that the GMCs of the fernA. nidus obtain a unique form, as a result of a particular polarity established in the cortical cytoplasm of the periclinal walls, in which Mts and Afs appear involved. This polarity persists in cell division and is “inherited” to guard cells (GCs). It provides primary morphogenetic information not only to GMCs but also to GCs.

Increasing vasoconstrictor response to ergonovine with oxidative injury in canine coronary artery.

The effects of oxygen free radicals on coronary vasoreactivity remain unknown. To examine whether oxygen free radicals increase coronary arterial tone and sensitivity to vasoconstrictor stimulation in closed-chest dogs. Oxygen radicals were generated by the reaction of xanthine plus xanthine oxidase (XXO) and effects of these substances on the left coronary artery (the percentage diameter change) and on the constrictor effect of ergonovine were examined in vivo in 19 anesthetized, closed-chest dogs by selective coronary angiography. The effects of XXO solution and ergonovine were assessed in a cumulative fashion using 100, 200, and 300 ml XXO and 50, 100, 150, and 200 micrograms ergonovine, in 5 (group I) and 6 dogs (group II), respectively. The effects of XXO on the constrictor responses elicited by 50 micrograms ergonovine were examined in eight dogs (group III). Changes in the vascular endothelium were examined by postmortem electron microscopic examination. Oxidative injury alone produced slight constriction of the coronary artery, but the change was not significant. However, ergonovine-induced vasoconstriction was enhanced after administration of 100 and 200 ml (cumulative amount) XXO solution (P < 0.05, group II versus group III). The enhancement was no longer observed after administration of 300 ml (cumulative amount) XXO solution. Scanning and transmission electron microscopies revealed the formation of blebs and ulceration in the coronary endothelium after administration of XXO solution. These results suggest that oxygen radicals can enhance the ergonovine-induced coronary vasoconstriction in a concentration-dependent manner. There seems to be a critical level of oxygen radicals for the production of the effect.

Sympathetic stimulation overrides flow-mediated endothelium-dependent epicardial coronary vasodilation in transplant patients.

Abnormal coronary vasomotor responses have been described in transplant patients. The aim of this study was to evaluate the graft epicardial vasomotor responses to different stimuli that increase coronary blood flow. Twelve heart transplant recipients with angiographically normal epicardial coronary arteries were compared 2.7 +/- 1.2 months after surgery with 6 control subjects. Coronary flow velocity was measured with a guidewire Doppler. Coronary diameter changes of the proximal and midportion of the left anterior descending coronary artery were assessed by quantitative coronary angiography during rapid atrial pacing, cold pressor test, supine exercise, and subselective infusion of papaverine and after intracoronary injection of linsidomine (SIN-1). Catecholamine plasmatic levels were determined at the different stages of the protocol. In 6 other transplant patients, a cold pressor test was performed before and after intracoronary infusion of phentolamine (10 micrograms.kg-1.min-1). Coronary flow velocity increased significantly in both groups during each phase of the protocol. In control subjects, dilation was observed in response to atrial pacing (8.7 +/- 7.6%; P < .05), CPT (8.8 +/- 2.3%; P < .01), exercise (14.5 +/- 9.4%; P < .001), and papaverine infusion (14.2 +/- 6.1%; P < .001) and after injection of SIN-1 (26.8 +/- 11.9%; P < .001). In transplant patients, similar dilation was observed during atrial pacing (8.2 +/- 8.3%; P < .05) and papaverine infusion (14.6 +/- 7.8%; P < .001) and after SIN-1 (25.8 +/- 10.8%; P < .001). CPT and exercise caused slight constriction (-3.5 +/- 4.5% and -2.7 +/- 10.5%, respectively; both P < .001 versus control subjects). Norepinephrine plasmatic levels increased in both groups during CPT and exercise. Slight constriction during the cold pressor test (-4.5 +/- 9.6%) changed to dilation (6.8 +/- 7.0%) after alpha-blockade with phentolamine (P < .001). These results show that flow-mediated, endothelium-dependent vasodilation is preserved early after trans-plantation. Sympathetic stimulation, which overrides the endothelium-dependent mechanism, can be related to hypersensitivity to catecholamines due to denervation.

Anesthesia for Aortic and Mitral Valve Replacement in a Patient with Carcinoid Heart Disease

Anesthesia for Aortic and Mitral Valve Replacement in a Patient with Carcinoid Heart Disease

Effect of Endothelin-1 and BQ 123 on Arterioles and Venules of Hypertensive Rats

We investigated the effect of the ETA-receptor antagonist BQ 123 (1.0, 5.0, and 10 mg/kg/h i.v.) on the endothelin-1 (ET-1) (10(-8) M)-induced vasoconstriction of arterioles in the cremaster muscle preparation of anesthetized SHRs. ET-1 10(-8) M led to a constriction of the arterial microvessels most marked in A4 arterioles (-92.9%) and least marked in A1 (-17.3%). The ET-1-induced constriction of venules was much less pronounced and showed no dependence on the vessel type. BQ 123 1.0 mg/kg/h was ineffective in antagonizing the vasoconstrictor effect of ET-1 in arterioles. With 5.0 mg/kg/h BQ 123, the ET-1-induced arterial vasoconstriction was inhibited by 68% in A4, by 44% in A3, by 39% in A2, and by 10% in A1 arterioles. BQ 123 10 mg/kg/h blocked the vasoconstrictor effect of ET-1 in all arteriole types by 79-93% and also reduced diastolic blood pressure in SHRs significantly at the end of the infusion period (-12.6 mm Hg). The ET-1-induced slight venous constriction was not affected by BQ 123.

Vasodilator innervation of small cerebral arteries of guinea pigs

The neuronal influence on the resistance of cerebral arteries was analyzed in middle cerebral arteries of guinea pigs. Calcitonin gene-related peptide- and vasoactive intestinal peptide-immunoreactive nerves and NADPH-diaphorase-positive nerves were present in the distal portion of the middle cerebral artery. Isolated middle cerebral arteries were cannulated and perfused at a constant flow rate (1 ml/min) and the perfusion pressure was monitored. Prostaglandin F 2α (PGF 2α) and K + (50 mM) elicited a sustained increase of the perfusion pressure (vasoconstriction), while noradrenaline and 5-hydroxytryptamine caused only a slight constriction. Electrical field stimulation (FS) at 8 Hz did not elicit a contractile response. In tissues precontracted with PGF 2α, FS induced a tetrodotoxin-sensitive vasodilator response. Endothelium-denudation and removal of the effect of sensory nerves by capsaicin-treatment did not affect the FS-induced vasodilation. In contrast, nitro- l-arginine, an inhibitor of NO formation, attenuated the FS-induced vasodilatation. These results show that the resistance of the cerebral vessels of guinea pigs is under the influence of vasodilator nerves and that the neurogenic vasodilator mechanism involves NO synthesis.