Inferior Half Research Articles

Sistema de pastejo rotativo "ponta e rapador" para novilhas de corte: 1. Desenvolvimento corporal

O objetivo deste trabalho foi avaliar o desenvolvimento de novilhas de corte no sistema de pastejo rotativo "ponta" e "rapador" durante o primeiro (Ano-1) e segundo (Ano-2) invernos/primaveras pós-desmama até o final do primeiro acasalamento aos 22-24 meses de idade. Setenta e seis bezerras de corte mestiças foram mantidas durante Ano-1 e Ano-2 em pastagem nativa melhorada de azevém (Lolium multiflorum L.) e trevo vesiculoso Yuchi (Trifolium vesiculosum cv. Yuchi). No período de verão/outono e acasalamento os animais foram mantidos em campo natural, em lote único. Os tratamentos Ponta (TP): grupo consumindo a metade superior da pastagem disponível; Rapador (TR): consumindo a metade inferior da pastagem foram testados. A evolução do peso vivo (PV) em cada etapa do experimento e ganho de peso médio diário (GMD) por período foram analisados. O peso vivo de TP diferiu do TR ao final do Ano-1 (195,6 vs. 168,1 kg), ao final do Ano-2 (316,3 vs. 274,1 kg) e ao início (318,5 vs. 275,7 kg) e final (341,5 vs. 304,4 kg) do acasalamento, respectivamente. O maior PV foi atribuído ao maior GMD obtido por TP sobre TR durante o uso da pastagem melhorada, com GMD de 0,790 vs 0,563 kg/dia e 0,753 vs. 0,522 kg/dia, no Ano-1 e Ano-2, respectivamente. Houve inversão no GMD com melhor desempenho do TR em relação ao TP (0,377 vs. 0,303 kg/dia) no acasalamento. O sistema de recria de novilhas para reposição, favorecendo determinado grupo de animais (TP), é uma das alternativas para obter pesos vivos satisfatórios, tornando-as aptas à concepção aos 22-24 meses de idade.

Transinferior Temporal Amygdalohippocampectomy for Temporal Lobe Epilepsy

Purpose: We describe a new surgical approach for removing the amygdalohippocampal complex. This approach does not require difficult surgical techniques, has had no complications so far, and the operative results have been excellent for obtaining sufficient seizure control. Methods: After a temporal craniotomy, the inferior temporal gyrus is exposed. A cortical incision, 15 nun superior and parallel to the temporal base, from the temporal tip to 50 mm (left side) or 60 mm (right side) posterior to it is made. The incision is deepened to reach to the arachnoid near the tentorial edge. When this is accomplished, the inferior temporal horn is opened widely, and the entire hippocampus is exposed. The hippocampus, as well as the parahippocampal gyrus, is removed in two pieces of ∼2 cm long each. The inferior half of the amygdala and the temporal basal cortex just in front of the head of hippocampus is also removed. Results: Of the 30 operated on cases that were followed up for > 1 year, 25 were completely seizure free, two had only a few auras a year, two had a few complex partial seizures a year, and one showed no change. This distribution is quite satisfactory. Conclusion: This approach is easy, but the results are satisfactory. Of course, the anterior temporal approach is the standard technique; however, the novel approach should be considered, especially when the entire hippocampus is to be removed.

The snapped inferior rectus

To evaluate the management and possible aetiology of the snapped inferior rectus muscle in strabismus surgery. Three patients are described whose inferior rectus muscle broke across its width some 8-10mm behind the insertion while being held on a squint hook without excessive force during strabismus surgery. The proximal part of the muscle was not found. The distal part of the snapped muscle was excised for pathological examination. Transposition of the inferior halves of the adjacent horizontal muscles to the insertion of the inferior rectus (a modified inverse-Knapp procedure) was performed in all cases. After the transposition surgery, one patient was orthotropic in the primary position, one patient required a prism correction to produce a range of single vision and the third patient was orthotropic after a further operation. There was good depression in one case and the other two had a limitation of depression. In all cases, horizontal movements remained intact and there were no signs of anterior segment ischaemia. The unique relations of the inferior rectus to the surrounding tissues may be a factor in causing the breaking of this muscle. Two of the patients were elderly and this may be a factor also. Transposition surgery is the appropriate management when the proximal part of the snapped muscle cannot be located and has satisfactory but imperfect results.

Contralateral Ureteral Meatal Advancement in Unilateral Antireflux Surgery

Purpose Contralateral vesicoureteral reflux is a well-known development after successful unilateral ureteral reimplantation that is not apparently influenced by the reimplantation technique. We sought to determine whether bilateral reimplantation should be performed routinely in unilateral cases. Materials and Methods From 1984 to 1995 we performed contralateral ureteral meatal advancement in 53 children 1 to 9.5 years old (mean age 2.5) undergoing surgery for unilateral grades II to V vesicoureteral reflux, including 12 with reflux in duplex systems. Ureteral meatal advancement involves a transverse Y shaped mucosal incision from the nonrefluxing orifice to the opposite hemitrigone. The inferior half of the ureteral orifice is then advanced toward the midline using 3 or 4 long-term resorbable sutures. The control group included 98 children who underwent unilateral surgery for grades II to V reflux from 1990 to 1995. Results No evidence of vesicoureteral reflux was observed in the 53 children who underwent contralateral meatal advancement. There was no obstruction or other complications. At followup contralateral reflux was found in 11 controls after unilateral reimplantation. Conclusions Contralateral reflux has been reported in up to 27% of previously reported cases and in 11% of our control group after successful unilateral antireflux surgery. Contralateral ureteral meatal advancement has proved effective for preventing reflux in 100% of cases. It requires minimal invasion of the nonrefluxing ureter, and little additional operative time and cost.

Morphological and structural characteristics of the proximal femur in human and rat

Because the ovariectomized rat model of postmenopausal osteoporosis is the most commonly used small animal model to investigate consequences of bone loss on bone structure and strength, or to assess benefits of the various therapeutic strategies to improve bone mass and strength, the attempt was made to compare histoanatomical and structural characteristics of the femoral neck between human and rat models. In addition to different biomechanics, there is a significant difference in gross- and microanatomy of the proximal femur between humans and rats. Percent of the cortical bone component is much higher in rats (72.5%) relative to humans (12.5%). Also, cortical bone at the femoral neck in rats is evenly distributed, whereas in humans there is a considerable difference in the amount of the cortical bone between the superior half of the femoral neck with cortical thickness being only 0.3 mm, and the inferior half of the neck having 6-mm-thick cortex. Humans have far more cancellous bone at the femoral neck (22.7% average) relative to rats (6.8%). In addition, cancellous bone at the femoral neck in humans is unevenly distributed between the bone center and its periphery. Human samples exhibited striking differences in the cancellous bone structure between weight-bearing and tensile trabecular groups exhibiting clear trabecular orientation consisting of plates and rods, and trabeculae around the neutral bone axis with little mechanical activity exhibiting rod-like trabeculae only. Although humans and rats have a periosteum covering the femoral neck, and each lacks the muscular attachment at Intracapsular portions of the femoral neck, rats, in contrast to humans, have the ability to quickly adapt cortical thickness and increase inertia to meet mechanical needs via modeling-dependent periosteal apposition.

Tympanic membrane changes in experimental purulent otitis media

The stiffness properties of the gerbil tympanic membrane (TM) were investigated during the early course of experimental purulent otitis media produced by middle ear inoculation (n=49) with type 3 Streptococcus pneumoniae. In a first approach the acoustic admittance and susceptance were measured in vitro with tympanometry and in a second approach the tympanic membrane displacement in response to static pressure was measured with moire interferometry. A histological assessment of the tympanic membrane was made concurrently. The acoustic admittance and susceptance reduced during the initial days post-inoculation. These reductions seem to correlate with an oedema simultaneously developing in the pars tensa. The pressure-induced displacement increased with time of disease, i.e. the mechanical stiffness of the TM reduced. Local deformation zones, or `weak spots' appeared in the inferior half of the pars tensa in three out of eight cases measured at 3 or 4 days post-inoculation. The loss of stiffness in the pars tensa may affect the further course of otitis media, and the `weak spots' are possible precursors of retraction pockets and/or perforations. The stiffness reductions may be caused by changes on a sub-microscopical, molecular level. ©1997 Elsevier Science B.V. All rights reserved

The spatio-temporal pattern of photoreceptor degeneration in the aged rd/rd mouse retina.

Photoreceptor degeneration in the retina of the rd/rd (retinal degeneration) mice has been studied using immunocytochemistry with antisera against cone- and rod-opsin. The rd/rd mice exhibited different regional specific rates of degeneration for rods and cones. As early as postnatal day 25, cells labelled with the rod-opsin and cone-opsin antisera disappeared preferently from the central retina. Whereas in the inferior half of the retina, degeneration subsequently proceeded towards the periphery, this did not occur in the dorsal hemisphere. By the age of 100 days, many cells immunoreactive for the cone-opsin antiserum and a few cells immunoreactive for the rod-opsin antiserum were located in an area of the dorsal retina. The ventral retina lacked labelled elements at this age. Finally, rd/rd mice at one year or 600 days of age contained a similar number of cone-opsin immunopositive cells (approximately 2000-2800 cells), occupying almost the same area in the retina as that found at 100 days of age. A photoreceptor candidate for the entrainment of non-visual photoreception probably remains in the cone population in aged rd/rd mice.

Eye infections after refractive keratotomy.

Ocular infections are serious and potentially vision-threatening complications of refractive keratotomy. We have performed an integrative review of published literature to address important issues concerning these complications. Articles in MEDLINE and published manuscripts and abstracts reporting previously unpublished cases of infections after refractive keratotomy were systematically identified and reviewed. Our review did not target patients treated with relaxing incisions for postkeratoplasty astigmatism. Pertinent data were abstracted and analyzed. Forty-three cases (47 episodes: 42 keratitis and 5 endophthalmitis) of infection appeared in 26 published reports from 1975 to 1994. The frequency ranged from 0.25% to 0.70%. In 22 (47%) eyes, infection occurred before 2 weeks. Thirty-five (74%) infections were located in the inferior half of the cornea, and 22 (62%) were located in the inferotemporal quadrant. Thirty-one (66%) infections were bacterial (32% gram-positive, 23% gram-negative, 9% acid fast, 496 unknown), 5% fungal, 6% viral, 19% sterile, and 4% of unknown origin. Spectacle-corrected visual acuity after conservative treatment was 20/40 or better in 70% of eyes. Penetrating keratoplasty was performed in six cases. Potential associations included reoperations in 12 (26%) eyes, postoperative contact lens wear in 7 (15%), and intraoperative perforation in 7 (15%). The published literature indicates that infections after refractive keratotomy may compromise visual function. Approximately half of the infections occur in the first 2 weeks. Reoperations, postoperative contact lens wear, and intraoperative perforations may be significant risk factors.

Use of perfluorocarbon liquids in proliferative vitreoretinopathy: results and complications.

The present study was set up to evaluate the influence of perfluorocarbon liquids on the postoperative anatomical and functional results as well as on the complication rates in eyes with proliferative vitreoretinopathy (PVR). Sixty five consecutive eyes (64 patients) with PVR in different stages requiring surgical intervention where liquid perfluorocarbons were used were compared with 64 consecutive eyes (62 patients) operated without the help of perfluorocarbon immediately before this time. Both groups were similar with regard to severity of PVR, number of operations, and initial visual acuity. The observation period was shorter in the perfluorocarbon group because they were operated more recently (17.4 months as against 24.4 months). The anatomical as well as the functional success rates were not significantly higher in the perfluorocarbon group (69% v 61% and 65% v 53% respectively). However, in cases operated on without perfluorocarbons where reproliferation would occur it was of much greater severity than in cases where perfluorocarbons were used. The number of uncured cases with contraction of the retina at least in the inferior half was more than twice as high in the group operated on without perfluorocarbon. Combined with massive reproliferation secondary glaucoma and bullous or band keratopathy were more frequent in eyes treated before the use of perfluorocarbon. The intraoperative use of perfluorocarbon liquids in vitreoretinal surgery does not prevent postoperative reproliferation but does reduce its severity.

Effect of partial retinal destruction and gliosis on the intravitreal pharmacokinetics of HPMPC.

Intravitreal HPMPC ([S]-1-[3-hydroxy-2 phosphonylmethoxypropyl cytosine) has a long antiviral effect in patients with cytomegalovirus retinitis. The authors evaluated the pharmacokinetics of intravitreal injections of HPMPC to understand major route of HPMPC elimination in a pigmented rabbit that had undergone scatter laser photocoagulation over half of the retinal surface. The authors treated the inferior half of the retina, receiving an average of 605 grade 3 or 4 (gray-white or white) diode laser burns in a scatter fashion in the left eyes of 13 rabbits. After 4 weeks, 13 rabbits received intravitreal injection of HPMPC (100 micrograms in 0.1 mL) in both eyes. Forty-eight hours after injection, unfixed vitreous samples were obtained for high-pressure liquid chromatography analysis. Two rabbits were used for light microscopic examination of diode laser photocoagulated retina with the perfusion fixation. The HPMPC concentration in the vitreous was 5.93 +/- 1.75 micrograms/mL in the laser-treated group and 4.76 +/- 1.2 micrograms/mL in the control group 48 hours after intravitreal HPMPC injection. The difference was statistically different (P = 0.037). Results showed a higher concentration of intravitreal HPMPC in the eye that had approximately 25% of the retina destroyed by the laser photocoagulation. The higher concentration is likely the result of reduced elimination and a concomitant increase in half-life. This suggests that HPMPC may be eliminated via the retinal route. Eyes with more extensive retinal involvement with human cytomegalovirus may have an even longer duration of action of intravitreal HPMPC. This may lead to modification of dosing regimens.

Anatomic Study of Arthroscopic Debridement of the Ankle

To this date, there have been no published studies correlating gross intra-articular anatomy and the compartments of the ankle that can be instrumented under arthroscopic visualization. The purpose of this study was to demonstrate which areas of intra-articular surface were accessible to the standard portals using a technique that allows direct anatomic correlation. Six fresh cadaver specimens and 12 fresh-frozen, below-knee amputations were used in this study. The 18 ankles were divided into six groups using only one arthroscopic portal site and one instrumentation site per group. Arthroscopic curettes were used to debride only the visualized talar, tibial, and fibular articular cartilage surfaces. After debridement, excision of the distal tibiofibular joint and the talus was performed. The total area of articular cartilage removed with each combination of arthroscope and instrument portal sites was noted, photographed, and recorded graphically. Use of the various combinations of the anteromedial, anterolateral, and posterolateral portals allowed complete access to all surfaces of the tibial plafond, anterior and posterior rims, and the talar dome. Areas that were not accessible by any portal combination were the distal half of the anterior colliculus of medial malleolus, the majority of the lateral talar articular surface, and the inferior half of the lateral malleolar articular surface.

Regional retinal blood flow reduction following half fundus photocoagulation treatment.

Regional changes in retinal blood flow following inferior and subsequent superior argon laser half fundus photocoagulation treatment were measured in six diabetic patients with advanced retinopathy. Centreline blood velocity, vessel diameter, and blood flow in major inferior and superior temporal retinal arteries were measured at baseline and following each treatment using the bidirectional laser Doppler technique and monochromatic fundus photography. Inferior fundus laser treatment produced a significant blood flow decrease in inferior temporal arteries ranging from 60% to 78%. Blood flow changes in superior temporal arteries were not significant, ranging from -7% to +14%. Subsequent superior fundus laser treatment produced a significant blood flow decrease in superior temporal arteries ranging from 50% to 66%. Subsequent blood flow changes in inferior temporal arteries were not significant, ranging from -19% to +21%. The results indicate that regional laser treatment produces a regional reduction in retinal blood flow, consistent with measurements of preretinal and intraretinal oxygen tension which have indicated increases in oxygen over photocoagulated regions.

Initial Argon Laser Trabeculoplasty to the Inferior vs Superior Half of Trabecular Meshwork

Previous studies of argon laser trabeculoplasty (ALT) have examined the effects of laser spot size, power, duration, anterior vs posterior spot placement, and extent of trabecular meshwork (TM) treated per session. Many surgeons perform ALT initially over 180° of TM and postpone further treatment if a sufficient response is obtained. Initially treating 180° of TM, reserving the other 180° until the initial treatment effect wears off, delays surgical intervention longer than initially treating 360° of TM. 1 Most people have greater meshwork pigmentation inferiorly than superiorly. To our knowledge, no prior studies have addressed whether initially treating one specific region of TM is equally efficacious as treating any other specific region. We hypothesized that the intraocular pressure (IOP) response to initially treating the inferior half of the TM might be detectably different compared with initially treating the superior half. Methods. One hundred two eyes of 80 consecutive patients with primary

Brain damage after profoundly hypothermic circulatory arrest: Correlations between neurophysiologic and neuropathologic findings: An experimental study in vertebrates

Five groups of neonatal pigs were subjected to cardiopulmonary bypass with circulatory arrest periods that varied from 70 to 120 minutes for the investigation of brain changes in induced deep-core hypothermia (15 degrees C) with circulatory arrest. The parameters that were analyzed were (1) microscopy of the brain in animals at 6 hours after bypass procedures and (2) intraoperative monitoring of somatosensory evoked potentials. Microscopic cellular damage appeared in all animals with a circulatory arrest period of more than 70 minutes. These changes involved mainly Purkinje's cells of the cerebellum, and they affected particularly the inferior half of the cerebellum. The prolongation of latency in the cortical responses, which reflects a slowing of the neural transmission with hypothermia, occurred in all animals. The late evoked potentials remained absent in all piglets with circulatory arrest periods of 90, 105, and 120 minutes, but they were fully recovered in all piglets of the control group and those with 70-minute arrest times. We concluded that the cerebellar region is the most sensitive site in which ischemic lesions attain their maximal severity and extent, and the maximum time of circulatory arrest without histopathologic and neurophysiologic sequelae should not exceed 70 minutes.

Appearance of the Hymen at Birth and One Year of Age: A Longitudinal Study

The increase in the number of prepubertal girls who require evaluation of possible sexual abuse creates a need for detailed information, not previously available from cross-sectional studies, on the influence of aging on the hymen's appearance. This study was undertaken to evaluate and document, using a longitudinal design, changes in the hymen's morphology in 62 girls without a history of sexual abuse between birth and their first birthday. Labial agglutination extensive enough to obscure the inferior half of the hymen was observed in 5 girls (8%) at 1 year of age. Thirty-three (58%) of the remaining 57 infants experienced a marked decrease in the amount of their hymenal tissue between birth and 1 year. Significantly more infants at 1 year of age had a crescentic configuration (0% vs 28%), and significantly fewer had an external ridge (82% vs 14%) as compared to the newborn period. An annular hymen with a central or ventrally displaced opening progressed to a crescentic hymen in 13 children by 1 year, 77% (10/13) of whom were observed to have a notch (cleft) at the 12 o'clock position on the earlier study. A superior notch appeared for the first time in 9 girls. Lateral notches resolved in 5 cases and persisted in 2. Inferior notches between the 4 and 8 o'clock positions were not observed at birth or 1 year. Hymenal tags resolved in 2 instances, persisted in the same location in 2, and appeared for the first time in 4 cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuropathological Features of Profoundly Hypothermic Circulatory Arrest: An Experimental Study in the Pig

Twenty-four neonatal pigs were exposed to periods of circulatory arrest of between 70 and 120 min under profound hypothermia at 15 degrees C. Brain tissue taken 6h after cardiopulmonary bypass was examined histologically and by electron microscopy for evidence of hypoxic damage. Specimens from control pigs and animals subjected to 70 min arrest showed no morphological changes in the cerebral or cerebellar neurones. The earliest changes were seen after 90-min arrest; these were highly significant after 120 min. The changes involved mainly the Purkinje cells of the cerebellum with vacuolation in the cytoplasm; the inferior half of the cerebellum was particularly affected. The frequency and pattern of selective vulnerability of the cerebellum may be related primarily to the nature of its blood supply.

Mucosal Folds of Eustachian Tube in Young Children

Differences in the extent of mucosal folding in the superior versus the inferior half of the human Eustachian tube (ET) were studied in young children by measuring the length of the mucosal margin and counting the number of mucosal folds, as they appeared in histological cross-sections, in the pharyngeal, midcartilaginous, isthmus, and osseous portions of each half of the ET in 12 normal ET/temporal bone specimens from 12 individuals aged 1 day to 2 years. The mucosal margin of the ET was significantly longer in the inferior half than in the superior half in the pharyngeal, midcartilaginous, and isthmus portions (paired t-test, pharyngeal portion: t[11] = 3.71, p < 0.01; midcartilaginous portion: t[11] = 4.52, p < 0.01; isthmus portion: t[11] = 3.40, p < 0.01). However, there was no significant difference between in the inferior half and in the superior half at the osseous portion. Also there were significantly more mucosal folds in the inferior half than in the superior half in all four portions (paired t-test, pharyngeal portion: t[11] = 3.46, p < 0.01; midcartilaginous portion: t[11] = 7.40, p < 0.01; isthmus portion: t[11] = 5.03, p < 0.01; osseous portion: t[11] = 4.49, p < 0.01). These results indicate that the surface area of the mucosa in the inferior half of the ET is larger than that of the superior half.(ABSTRACT TRUNCATED AT 250 WORDS)

Mucosal Folds in Human Eustachian Tube: A Hypothesis regarding Functional Localization in the Tube

Differences in the extent of mucosal folding in the superior versus the inferior half of the human eustachian tube (ET) lumen were studied by measuring, as it appeared in histologic cross section, the length of the mucosal margin in the pharyngeal portion, the midcartilaginous portion, the isthmus portion, and the osseous portion of each half of the ET in 16 normal ET temporal bone specimens from 16 individuals 12 to 70 years of age. The mucosal margin of the ET was significantly longer in the inferior half than in the superior half in all four portions (paired t test: pharyngeal portion t[15] = 3.59, p < .01; midcartilaginous portion t[15] = 3.52, p < .01; isthmus portion t[15] = 4.15, p < .01; osseous portion t[15] = 2.24, p < .05). These results indicate that the inferior half of the ET mucosa has more folds than the superior half, and that the surface area of the inferior half of the ET is larger than that of the superior half. This, together with the finding previously reported that secretory components of the ET such as glands and goblet cells are more richly distributed in the inferior (floor) portion than in the superior (roof) portion of the ET, may be related to the fact that the floor of the ET has an active role in clearance function. A hypothesis regarding localization of the ventilatory and clearance functions within the ET is proposed.

Relationship between the development of diaphragma sellae and the morphology of the sella turcica and its content.

The impaired formation of the diaphragma sellae may lead to the development of the empty-sella syndrome. This structure, when fully formed, is a protective barrier against the pulsating action that the cerebrospinal fluid exerts on the sellar content. There are anatomical features which support this belief, but they also suggest that the development of the diaphragma sellae is a factor which determines the morphology of the sella turcica and its contents. Those human specimens which do not have diaphragma sellae or in which it is only partially developed, are characterized by a smaller hypophysis, always located at the inferior and/or posterior half of the sella, with a larger sellar volume and frequently greater fragility of its bony walls. These findings, although rare (5% of the cases), are indirect signs of the important role which the diaphragma sellae plays in the sellar region.

Tricompartment Model of the Lacrimal Pump Mechanism

The role of the lacrimal sac in the lacrimal pump mechanism is controversial. Movements of the lateral wall of the lacrimal sac with blinking were videotaped through an endoscope in eight patients after dacryocystorhinostomy. In addition, movements of an air bubble at the opening of the nasolacrimal duct with blinking were studied in three patients with an incompetent valve of Hasner. The superior half of the lateral wall of the lacrimal sac moved laterally with lid closure and medially with lid opening. The inferior half of the lateral wall of the lacrimal sac moved medially with lid closure and laterally with lid opening. In patients with an incompetent valve of Hasner, the air bubble at the opening of the nasolacrimal duct bulged into the nose with lid closure and retracted into the nasolacrimal duct with lid opening. A tricompartment model of the lacrimal pump is presented that incorporates these findings. With lid closure, the orbicularis muscle contracts, compressing the canaliculi and pulling the superior half of the lateral wall of the lacrimal sac laterally. This creates a lower pressure in the superior sac, allowing tears to be propelled from the canaliculi into the sac. At the same time, the inferior half of the lateral sac wall moves medially, creating a positive pressure in the inferior sac and nasolacrimal duct, thus forcing tears down the duct into the nose. With lid opening, the orbicularis muscle relaxes, allowing the canaliculi to open and the superior half of the lateral sac wall to move medially. The resulting negative intracanalicular pressure allows tears to flow from the lacrimal lake into the canaliculi, and the higher pressure in the superior sac closes the valve of Rosenmueller and forces tears from the superior to inferior sac and proximal nasolacrimal duct. At the same time, the inferior half of the lateral sac wall moves laterally, resulting in a negative pressure in the inferior sac and nasolacrimal duct.