Esophageal Region Research Articles

Src activation in malignant and premalignant epithelia of Barrett's esophagus

BACKGROUND & AIMS: The neoplastic progression of Barrett's esophagus (BE) may involve genomic instability, inactivation of tumor suppressor genes, or activation of oncogenes. Because activation of Src tyrosine kinase occurs in malignant and premalignant epithelia of the colon, the aim of this study was to determine whether BE is associated with changes in Src expression and activity.METHODS: Src expression and in vitro protein-tyrosine kinase activity in endoscopic tissue samples of BE and esophageal adenocarcinoma were measured and compared with expression and activity in normal esophagus and duodenum from the same patient. Src phosphorylation was assessed by immunoblotting using antiphosphotyrosine antibodies and two-dimensional tryptic phosphopeptide mapping.RESULTS: Src-specific activity was 3-4 fold higher in BE and 6-fold higher in esophageal adenocarcinoma than in control tissues. Different regions of BE from the same patient showed heterogeneity in Src activity compared with the uniform Src activity observed in different regions of normal esophagus and duodenum. In all tissues, Src kinase activity and protein were associated preferentially with the Triton X-100-soluble rather than-insoluble fraction. Immunoblotting and two-dimensional tryptic phosphopeptide mapping showed dephosphorylation of Src at Tyr527 in BE.CONCLUSIONS: Src is activated in BE, in part, because of dephosphorylation of Tyr527. Src activation and its heterogeneous expression occur before development of dysplasia or carcinoma in BE.(Gastroenterology 1997 Feb;112(2):348-56)

Enrichment of single kidney proximal tubulus cells for genotoxicity testing

Subsistence farmers are exposed to a range of mycotoxins. This study applied novel urinary multi-mycotoxin LC–MS/MS methods to determine multiple exposure biomarkers in the high oesophageal cancer region, Transkei, South Africa. Fifty-three female participants donated part of their maize-based evening meal and first void morning urine, which was analysed both with sample clean-up (single and multi-biomarker) and by a ‘dilute-and-shoot’ multi-biomarker method. Results were corrected for recovery with LOD for not detected. A single biomarker method detected fumonisin B1 (FB1) (87% incidence; mean ± standard deviation 0.342 ± 0.466 ng/mg creatinine) and deoxynivalenol (100%; mean 20.4 ± 49.4 ng/mg creatinine) after hydrolysis with β-glucuronidase. The multi-biomarker ‘dilute-and-shoot’ method indicated deoxynivalenol-15-glucuronide was predominantly present. A multi-biomarker method with β-glucuronidase and immunoaffinity clean-up determined zearalenone (100%; 0.529 ± 1.60 ng/mg creatinine), FB1 (96%; 1.52 ± 2.17 ng/mg creatinine), α-zearalenol (92%; 0.614 ± 1.91 ng/mg creatinine), deoxynivalenol (87%; 11.3 ± 27.1 ng/mg creatinine), β-zearalenol (75%; 0.702 ± 2.95 ng/mg creatinine) and ochratoxin A (98%; 0.041 ± 0.086 ng/mg creatinine). These demonstrate the value of multi-biomarker methods in measuring exposures in populations exposed to multiple mycotoxins. This is the first finding of urinary deoxynivalenol, zearalenone, their conjugates, ochratoxin A and zearalenols in Transkei.

Neural network-based detection of esophageal intubation in anesthetized patients.

To test whether a neural network-based method could differentiate between tracheal and esophageal intubation in anesthetized patients by recognizing breathing circuit pressure and flow waveform patterns. Tracheal tubes were placed in the trachea and in the esophagus of adult patients undergoing elective operations. After ensuring for proper oxygenation, ventilator settings were changed to 5 ml/kg tidal volume (VT) and 15 cpm and circuit pressure and flow were recorded for 15 seconds. Then, the breathing circuit was switched to the tube placed in the esophagus, and signals were recorded for an additional 15-second period. During off-line analysis, individual waveforms were separated. Tracheal breaths were labeled with a score of 1 while esophageal "breaths" were labeled with -1. A neural network was defined to learn to associate waveforms to their corresponding scores. Data from 54% of the patients were used to train the neural network. Data from the remaining subjects were used for testing. Forty-six patients were studied. Neural network training was achieved with 100 tracheal and 94 esophageal waveforms from 25 patients. Neural network performance was tested on 84 tracheal and 76 esophageal waveforms from 21 subjects. The neural network assigned scores of 0.99 +/- 0.05 (mean +/- SD) to tracheal waveforms and -0.99 +/- 0.03 to esophageal waveforms. The difference between mean esophageal and tracheal scores was -1.99 with a 99.999% confidence range of -2.01 to -1.96. Any arbitrary cutoff threshold, ranging between -0.76 and 0.7, separated tracheal and esophageal score regions, yielding no false positive or negative results. A neural network differentiated consistently tracheal from esophageal intubation when the ventilation test mode was used. The ventilation mode employed is feasible in most adult patients undergoing elective procedures under general anesthesia. Further research is required to train neural networks to recognize esophageal intubation in different age groups and when different ventilation modes are applied.

A survey of the relationship between bile staining and oesophagogastric lesions in slaughter pigs

In 280 slaughter pigs, the oesophageal region of the stomach was examined to test the hypothesis that there is a (causal) relationship between the intensity of bile staining of oesophagogastric tissue due to bile regurgitation and the severity of oesophagogastric lesions. When the stomachs were opened, almost all stomachs contained bile and 99.6% of stomachs showed bile staining of the pars oesophagea. A total of 14.3% of the stomachs showed distinct erosions and/or ulceration. A considerable proportion of the stomachs (58.5%) had hyperkeratosis as the only lesion. Only two animals showed a completely intact epithelium. There was no evidence for an increased proportion of oesophagogastric lesions with an increased intensity of bile staining. No dark yellow to green staining was observed; a just detectable to an obvious yellow was seen. This is an indication for bile regurgitation of recent origin. Therefore, there is no evidence for the hypothesis that the regurgitation of bile into the stomach is positively linked to the occurrence of oesophagogastric lesions in fattening pigs. It is suggested that various factors associated with slaughter, such as fasting and slaughter procedure, are primarily responsible for the presence of bile and the staining of the pars oesophagea in the stomachs.

Descending peristaltic reflex in the opossum esophagus

To test the hypothesis that the distension-induced esophageal peristaltic reflex involves a polysynaptic pathway, a triple-chamber organ bath was used to chemically isolate different regions of the opossum smooth muscle esophagus while leaving in continuity the intramural neuromuscular apparatus. Balloon distension in the oral chamber evoked membrane hyperpolarization in the aboral chamber, which was followed, on balloon deflation, by depolarization, spike burst, and circular smooth muscle contraction. This reflex was abolished by adding tetrodotoxin to any of the chambers. Addition of Ca(2+)-free 20 mM Mg2+ Krebs solution (to block synaptic transmission) to the intermediate chamber did not affect the descending peristaltic reflex. However, Ca(2+)-free 20 mM Mg2+ Krebs solution markedly attenuated the reflex when placed in either the oral or the aboral chamber. Furthermore, the nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester, when placed in the aboral chamber, abolished the reflex. Other putative neurotransmitter antagonists were without effect when placed in any chamber. These studies suggest that the intramural neural pathway that mediates the descending peristaltic reflex in the opossum esophagus is not polysynaptic, but rather involves long descending neurons that depend on nitric oxide as a final mediator.

Mesoderm-specific B104 expression in the Drosophila embryo is mediated by internal cis-acting elements of the transposon.

The Drosophila melanogaster genome contains about 100 copies of the B104 transposable element, which is strongly expressed during embryogenesis. Here we show that B104 expression is restricted to the esophageal and amnioproctodeal regions of the embryo and to the developing mesoderm. Mesoderm-specific B104 expression requires the activity of the mesoderm-determining factors twist and snail. Virtually the same expression patterns were observed in Drosophila yakuba, a species that a separated from D. melanogaster by some 15 million years of evolution. We show that B104 expression is directed by internal sequences of the retrotransposon that are capable of acting as a cis-acting regulatory element in front of a heterologous Drosophila promoter. Our findings suggest that retrotransposon insertions can affect the expression patterns of endogenous genes by adding and distributing specific cis-acting control elements throughout the host genome. We therefore propose that transposable elements in addition to reducing the fitness of their hosts may also provide a rich pool of cis-acting sequences that contribute to the long-term evolutionary potential of the population in a beneficial manner.

Reducing particle size of corn in lactation diets from 1,200 to 400 micrometers improves sow and litter performance

One hundred primiparous sows were used to determine the effects of particle size of corn in lactation diets on sow and litter performance. The sows were fed a corn-soybean meal-based diet with the corn ground to 1,200, 900, 600, or 400 microns. Particle size of corn had no influence on sow BW or backfat loss (P > .30), subsequent weaning-to-estrus interval (P > .40), or percentage of sows returning to estrus (P > .09). However, ADFI was increased (linear effect, P < .04) as particle size was reduced from 1,200 to 400 microns. Pig survivability was not affected (P > .30) but litter BW gain was increased by 11% when sows were fed diets with 400 vs 1,200 microns corn (linear effect, P < .05). Apparent digestibilities of DM, N, and GE were increased by 5, 7, and 7%, respectively, as particle size was reduced from 1,200 to 400 microns (linear effects, P < .001). Intake of DE was increased 14% (13.7 to 15.6 Mcal/d) as corn particle size was reduced from 1,200 to 400 microns. Intakes of digestible DM and N also were increased (11 and 14%, respectively), whereas fecal excretions of DM and N were decreased by 21 and 31%, respectively (linear effects, P < .001). Reducing particle size increased severity of ulceration and keratinization (nonzero correlations of P < .04 and P < .004, respectively) in the esophageal region of the stomach, although the changes were not associated with reduced sow performance.(ABSTRACT TRUNCATED AT 250 WORDS)

A CASE OF PRIMARY MALIGNANT MELANOMA OF THE ESOPHAGUS

This paper reports here a case of primary malignant melanoma of the esophagus. A 59-year-old female was admitted to the hospital because of dyshagia. Barium meal and endoscopic examinations revealed a blackish tumor with an uneven surface located in the Im and Ei regions of the esophagus. Biopsy of the tumor disclosed primary malignant melanoma of the esophagus. Esophagectomy was performed. The resected tissue material included a 4×3×2cm subpedunculate tumor and a 1×1×1cm small raised lesion in the Im and Ei regions of he esophagus. Histological examination demonstrated malignant melanoma. Postoperative adjuvane chemotherapy was begun, but 7 months after the surgery hepatic metastases were noted. Twenty-three months after the surgery metastases to the neck and mediastinal lymph node were noted, and irradiation was added to the treatment. However, the patient died 26 months after the surgery. Primary malignant melanoma of the esophagus is rare. This is the 97th case in Japan. An analysis of these cases is also presented.

Dysphagia after pharyngolaryngeal cancer surgery. Part II: Implications for reconstructive procedures.

In the base of the tongue region, reconstructive procedures have to provide more bulky-tissue coverage (i.e., myocutaneous flaps) in order to avoid cranial release of pressure and to bring about swallowing initiation. Resections of the pharyngoesophageal (PE) segment cause circular defects, always affecting the sphincter and necessarily relaxation, thus reducing the hypopharyngeal suction pump. The resistance to bolus flow, therefore, is generally increased but can be compensated by a stronger tongue driving force. In addition to the functional obstruction, special attention is called to the growing lumen discontinuity between the wide pharynx and the narrow esophagus. Plastic reconstructions, therefore, have to compensate for different lumina distally. Following ablative surgery in the upper esophageal sphincter region, a softer and smoother tissue coverage is warranted in order to facilitate bolus transfer to a passive bolus flow if necessary. For that purpose, a new myofascial pectoralis flap was designed based on morphometric investigations and postmortal selective injection studies. In this flap, the bulky muscle mass is separated from just a vascularized, thin fascia-muscle layer. The donor site is covered with the remaining bulky muscle-skin complex left intact. The fascial flap covers defects where a soft lining is required and replaces the PE segment as a tubed neopharynx. Histologic specimens show a reepithelization with local mucous membrane from the anastomotic site to the fascial surface. The resistance to bolus flow is reduced, thus alleviating the tongue driving force, which is increased for compensation in any case.

Ultrastructure of the metanephridial system in Aeolosoma bengalense (Annelida)

The excretory system of Aeolosoma bengalense has been examined by light and electron microscopy. The system consists of seven serially arranged paris of metanephridia and six pairs of podocytes (referring to the first zoid of an animal chain). The podocytes surround blood spaces of the alimentary canal forming dorsoventrally running loops that emerge on both sides of it. The two elements of the system have a correlative position, each podocyte extending in close proximity to the funnel of a metanephridium. Only in the region of the first metanephridia are podocytes lacking. The nephrostome of the metanephridia consists of two cells, an inner one, the terminal duct cell, and an outer one enwrapping it, called the mantle cell. Nephrostomal cilia that extend into the coelomic space arise exclusively from the rim of the mantle cell whereas those of the terminal duct cell arranged on its luminal surface protrude into the canal forming a flame. The nephridial canal is ciliated throughout and is either intra- or extracellular. Its initial loops aggregate to form a compact organ, the nephridial body. The middle part of the duct constitutes a loop that ascends at each side of the alimentary canal where it is in intimate contact with its blood spaces. Ultrastructural features of the duct cells suggest a reabsorptive function in two regions, the nephridial body and the uppermost part of the loop. The terminal part of the duct passes through the nephridial body and opens ventrolaterally. Generally, the transverse vascular loops at the gut consist of one podocyte each. In the oesophageal region, where only one pair of podocytes is present, the loops connect the dorsal with the ventral longitudinal vessel. Three pairs of podocytes are present in the dilated region of the intestine emerging from its lateral wall and joining the median ventral vessel or blood spaces near by. In the hind gut, where two pairs of podocytes occur, the loops arise from the dorsolateral part and enter directly the ventral vessel. Cytological features of podocytes resemble those of other animals. The results are discussed on the basis of current theories on the function and the phylogenetic significance of excretory systems in the Annelida.

Influence of Low-Level Exposure to Fusarium Mycotoxins on Selected Immunological and Hematological Parameters in Young Swine

Influence of Low-Level Exposure to Fusarium Mycotoxins on Selected Immunological and Hematological Parameters in Young Swine. Rotter, B. A., Thompson, B. K., Lessard, M., Trenholm, N. L., and Trypbonas, H. (1994). Fundam. Appl. Toxicol. 23, 117-124.The effects of low dietary concentrations of Fusarium mycotoxins (deoxynivalenol (DON), 15-acetyl-DON, and zearalenone) on growth, immunological, and hematological parameters were determined in young pigs during a 28-day feeding experiment. Clean and naturally contaminated corn were incorporated into basal diets formulated to contain 0.00, 0.75, 1.50, and 3.00 mg DON/kg diet. A pair-fed control animal was used for comparison with each animal receiving the highest level of contamination (diet 4). Skin temperature, measured during the first week of the experiment, decreased linearly as the dietary mycotoxin concentration increased. Several other linear effects were observed: depressed feed intake throughout the experiment, reduction in thyroid size (absolute/relative), and changes in the appearance of the esophageal region of the stomach (thicker and higher degree of folding with increasing toxin concentration). Serum T4 (thyroxine) levels increased quadratically after 7 and 28 days of exposure compared to control animals. This change coincided with an increase in albumin levels, a decrease in α-globulin levels, and an overall increase in albumin/globulin ratio as the level of contamination increased. After immunization with sheep red blood cells (SRBC), animals fed contaminated diets showed a delayed response in peak titers. At the end of the experiment an increase in the segmented neutrophil count was observed. The following observations were made for animals consuming diet 4 as compared to the pair-fed controls: lower skin temperature, better feed efficiency, more corrugated stomachs, reduced α-globulin levels, and lower antibody titers to SRBC. The study showed a physiobiochemical adaptation response of animals exposed to mycotoxin-contaminated diets. Although most changes seem to be related to the nutritional status of the animal, others such as reduced skin temperature, altered stomach condition, and reduced α-globulin levels suggest specific effects due to the Fusarium toxins. The pair-feeding treatment was important in reaching these conclusions, but it is also evident that the treatment itself introduces changes in response to a reduced feed intake.

Effects of feeding diets containing Fusarium (naturally) contaminated wheat or pure deoxynivalenol (DON) in growing pigs

Three experiments were conducted to determine the effects of feeding diets containing laboratory synthesized deoxynivalenol (DON), or Fusarium (naturally) contaminated wheat containing DON on performance and health of young pigs (32.8–41.1 kg body weight). Diets containing 3.4–19.1 mg DON kg−1 were fed to pigs ad libitum for 14 d (exps. 1 and 2) or 7 wk (exp. 3) after which time each pig was slaughtered and blood, tissue and organ samples taken for analysis. All pigs responded to DON-contaminated diets with an immediate reduction in feed intake and body weight gain followed by some degree of recovery that was dependent on the dietary DON concentration. Negative linear relationships were found between feed intake or body weight gain and dietary DON concentration with pure DON and naturally contaminated wheat diets. Feed intake and weight gain were, respectively, 18 and 23% lower when a diet containing naturally contaminated wheat was fed compared to a diet containing an equivalent concentration of pure DON. Effects of DON on organ weights, relative to body weight, were inconsistent among experiments. The gastric mucosa was thinner and more eroded and had a higher degree of folding in the esophageal region in most groups fed DON-contaminated diets compared to those fed the control diet. Effects of DON on the fundic and cardiac regions of the stomach were inconsistent among treatments and experiments. There was little or no effect of DON on most of the blood parameters measured. Key words: Pure deoxynivalenol, naturally contaminated wheat, swine, intake, gain, vomitoxin, mycotoxin, fusarium, trichothecene

The role of the frontal ganglion in foregut movements of the moth, Manduca sexta

Two types of rhythmic foregut movements are described in fifth instar larvae of the moth, Manduca sexta. These consist of posteriorly-directed waves of peristalsis which move food toward the midgut, and synchronous constrictions of the esophageal region, which appear to retain food within the crop. We describe these movements and the muscles of the foregut that generate them.The firing patterns of a subset of these muscles, including a constrictor and dilator pair from both the esophageal and buccal regions of the foregut, are described for both types of foregut movement.

The significance of methicillin-resistant Staphylococcus aureus infection in general surgery: a multivariate analysis of risk factors and preventive approaches.

To investigate the characteristics, risk factors, and prevention of methicillin-resistant Staphylococcus aureus (MRSA), a total of 3,627 patients were studied. Among these, 1,336 patients with various infections were used in a risk factor analysis of MRSA to determine the relationship between the use of antibiotics and the incidence of MRSA. Only 3.0% of infections were attributed to MRSA, the esophagus and colorectal region being highly involved, as anastomotic or pelvic abscesses, while the lung had a lower incidence. Almost half the patients with MRSA infections (47.6%) had concomitant infection. A univariate analysis revealed the following significant factors: The coexistence of gastrointestinal or metastatic malignancy, sepsis, tracheostomy, and the prior use of antibiotics such as the beta-lactam compounds or aminoglycosides. A multivariate analysis showed that gastrointestinal malignancy, sepsis, and the prior use of aminoglycosides, tetracycline, macrolides, and carbapenems were independently significant factors. To promote the education of doctors and nurses, regular in-service meetings on MRSA were held in the ward. Moreover, preventive approaches such as patient isolation, strategically placed hand washing equipment, and the use of disposable gloves and contaminated waste bags, have been initiated, and the incidence of MRSA has decreased significantly since then. Thus, to control MRSA, the following steps should be taken: (1) constant and careful surveillance, (2) regular risk factor analyses, (3) the optimal administration of antibiotics, and (4) the education of all hospital staff.

Nucleus ambiguus of the rabbit: cytoarchitectural subdivision and myotopical and neurotopic representations.

The cytoarchitectural subdivisions of the nucleus ambiguus of the rabbit and its myotopical and neurotopical representations were investigated with HRP labeling. The nucleus was subdivided into the compact cell group (CoG), the medial and lateral scattered cell groups (SGm and SGl), and the diffuse cell group (DiG). The CoG was formed by esophageal, pharyngeal constrictor, and palatal motoneurons in the rostral half of the nucleus. The SGm and SGl were located medial and lateral to the CoG, respectively, in the rostral one-third of the nucleus. Stylopharyngeal and cricothyroid motoneurons were located in the most rostral one-fifth of the SGm and the remaining four-fifths, respectively, whereas the SGl was not labeled with HRP injections into the palatal, pharyngeal, esophageal, and laryngeal muscles. The DiG was formed by recurrent laryngeal motoneurons in the caudal two-thirds of the nucleus. Neurons of origin for the glossopharyngeal nerve occupied the stylopharyngeal region, with a few of them scattered in the CoG and SGl. Neurons giving rise to axons in the superior laryngeal nerve occupied the cricothyroid region, with a few of them scattered in the pharyngeal constrictor region; whereas the pharyngeal vagal branch originated from the pharyngeal constrictor and palatal regions. Neurons of the DiG, SGl, and esophageal region contributed to the infranodosal vagus nerve; esophageal fibers of the recurrent laryngeal nerve originated from the dorsal esophageal region. Laryngeal fibers of the recurrent laryngeal nerve originated from the DiG, the caudal neurons of which had axons traversing the cranial accessory root.

Splenic venous flow exceeding portal venous flow at Doppler sonography: relationship to portosystemic varices.

The purpose of this study was to determine if the Doppler sonographic finding of hepatopetal flow in the splenic vein that exceeds hepatopetal flow in the portal vein is associated with portosystemic varices. Sixty-four patients with chronic liver disease were studied retrospectively. In 32 patients, splenic venous flow exceeded portal venous flow (S > P group); in 32 patients, portal venous flow exceeded splenic venous flow (P > S group). All patients were evaluated with Doppler sonography and CT of the upper part of the abdomen. Upper endoscopy was performed within 3 months of sonography in 44 of the 64 patients. In the S > P group, mean splenic volume was significantly larger (p = .02) than in the other group. The prevalence of varices as determined by CT in the esophageal, coronary, and peripancreatic regions was also higher in this group (p < or = .01). When esophageal varices were present, they were judged on the basis of their CT appearance to be massive in 50% of the S > P group and in 0% of the P > S group. Upper endoscopy revealed esophageal varices in 92% of the S > P group and in 55% of the P > S group (p < .005). Bleeding esophageal varices were noted in 75% of the S > P group and in 30% of the P > S group (p < .01). Patients with chronic liver disease and the Doppler sonographic finding of splenic venous flow that exceeds portal venous flow have an increased prevalence of portosystemic varices, which tend to be larger and more likely to bleed.

The search for the central swallowing pathway: the quest for clarity.

As the work of Dr. Martin Donner has brought a clarity to understanding swallowing, so has the work of various neuroscientists, including that of a Nobel Laureate, in providing us with a better comprehension of this complex motor pattern. Understanding the neural control of swallowing has been a process that has occurred during this century in which several investigators, primarily from Europe, Japan, Canada, and the United States, have brought their perspectives in applying particular techniques to decipher how the central and peripheral nervous system control swallowing. Swallowing represents a complex muscular response of the oral, pharyngeal, and esophageal regions which are integrated to provide an effective functional pattern that prepares and transports food while simultaneously protecting the airway. This adaptation of the upper gastrointestinal tract in mammals has been extensively studied peripherally by two methods: recording from the peripheral nerves and muscles, and stimulating peripheral nerves and their receptive fields that can induce the pharyngeal and esophageal phases of swallowing. The study of the peripheral nervous system has provided insight into the sensory receptive fields that evoke or facilitate swallowing, and has established the first serious evidence of the all-or-none sequential contraction pattern of the oropharyngeal and esophageal muscles. It has been these electromyographic studies of the muscles that has established much of the criteria for evaluating the central swallowing pathway. Five techniques have been applied to the central nervous system to study swallowing and include lesioning or destroying discrete regions to determine how swallowing is impaired or modified, electrically stimulating the central neural tissue to determine the type of effects on swallowing, recording from the central neural tissue with macro- and microelectrodes to ascertain when neurons respond in timing to the peripheral muscle activity during swallowing, applying pharmacological agents through micropipettes which could mimic or inhibit potential transmitters, and using immunochemical techniques to tag specific chemicals that could be transmitters used by the neurons in the central swallowing pathway. These various techniques have provided insight into how the central swallowing pathway is organized but the details of the central control are still in the process of being defined and will require as much effort this next century as has been previously developed over the past 90 years.

Megaoesophagus in rats: A clinical, pathological and morphometrical study

Megaoesophagus was observed in 82 Long-Evans rats aged 3-32 months. Clinically, the hair was coarse, the neck distended, the mouth opened, wetted by saliva and soiled by bedding material, and the respiration characterized by tachypnoea and inspiratory crackles. By radiography, after barium administration, the oesophagus was seen to be dilated and filled with impacted dry food in the precardial region. The size of the dilatation varied depending on the oesophageal region and reached a diameter of 12 mm in the most severe case. Histologically, the muscular layers of the dilated portions showed focal inflammation and single fibre necrosis. Each affected oesophagus had (1) an increased circumference and radius and a reduced number of myenteric ganglion cells in both the thoracic and abdominal portions, and (2) a decreased thickness of the muscular layers in the thoracic portion and at the level of the cardia. A simple geometrical model showed that the reduced ganglion cell number was not due to a change in shape of the dilated oesophagus. Since no sign of infectious disease was found in these animals, and rats of other strains kept at the same time under the same conditions were not affected, a hereditary aetiology is suggested.

Toxicity of T-2 toxin and its interaction with deoxynivalenol when fed to young pigs

Sixty 12-wk-old pigs were fed a corn–barley–soybean type diet in a 2 × 5 factorial experiment. Two mycotoxin, corn-based premixes were added: one with and without deoxynivalenol (DON) supplement (2.5 mg kg−1 feed) and the other with T-2 toxin at levels of 0.0, 0.4, 0.8, 1.6 and 3.2 mg kg−1 feed. After a 5-wk feeding period the pigs were killed; major organs were examined grossly and microscopically, and blood and tissue samples were taken for biochemical and hematological analyses. Lower final body weight and daily gain appeared (P &gt; 0.05) to be associated with increasing dietary T-2 toxin content. Feed intake followed a similar trend. The performance of pigs fed the DON-supplemented diets was significantly less than for diets without the DON. There was an interaction between DON and T-2 toxin, with differences in weight gain and feed intake, at the two levels of DON, being smaller at the intermediate levels of T-2 toxin. The incidence of lesions on the mucosa of the pars esophageal region increased with increasing levels of T-2. Otherwise, there was little evidence that T-2 affected any of the major organs examined at necropsy or the biochemical and hematological criteria. It seemed that any effects detected were attributable more to DON and its interaction with T-2 than to the presence of T-2 toxin alone. Key words: Pigs, T-2 toxin, DON, toxin interaction

Basement membrane lectin binding sites are decreased in the esophageal endoderm during the arrival of presumptive muscle mesenchyme in the developing asteroid Pisaster ochraceus.

Basement membranes (BMs) of vertebrates and invertebrates have been shown to contain glycoproteins and proteoglycans, which include oligosaccharides and glycosaminoglycans. Lectin binding sites were characterized in the BM of gastrulating embryos of the starfish, Pisaster ochraceus. In early and mid-gastrulae, the fluorescein isothiocyanate (FITC)-lectin conjugates of concanavalin A (Con A) and wheat germ agglutinin (WGA) reveal the presence of mannose/glucose and glucosamine/sialic acid residues in the BM of all regions of the embryos. However, in the late gastrula embryo, an apparent reduction of these components is observed over the esophageal BM. Ultrastructural studies using the lectin-gold conjugates Con A, Limax flavus agglutinin (LFA), specific for sialic acid, and Dolichos biflorus agglutinin (DBA), specific for galactosamine, demonstrate that most mannose/glucose and galactosamine-containing residues lie in the lamina densa, whereas most sialic acid residues are located over the lamina lucida. In addition, a statistical analysis of lectin binding in the late gastrula embryo reveals that the amount of labelling with both Con A and LFA is significantly reduced in the esophageal region, suggesting that mannose/glucose and sialic acid residues are reduced in this region. These results confirm the observations of the FITC-lectin studies described above. They also confirm earlier studies that demonstrated a difference in BM morphology of the esophageal region (Crawford, '88). Mesenchyme cells, some of which arise from the forming coeloms (Crawford, '90), and which may represent a distinct population, colonize exclusively on this esophageal BM, where they later differentiate into muscle. Quantitative differences in BM glycoconjugates may act to direct the presumptive muscle cells to the region of the esophagus.