Receptor Tyrosine Kinases ror1/2 and ryk Are Co-expressed with Multiple Wnt Signaling Components During Early Development of Sea Urchin Embryos.

AbstractA combination of receptors, co-receptors, and secreted Wnt modulators form protein complexes at the cell surface that activate one or more of the three different Wnt signaling pathways (Wnt/ß-catenin, Wnt/JNK, and Wnt/Ca2+). Two or more of these pathways are often active in the same cellular territories, forming Wnt signaling networks; however, the molecular mechanisms necessary to integrate information from these pathways in these situations are unclear in any in vivo model system. Recent studies have implicated two Wnt binding receptor tyrosine kinases, receptor tyrosine kinase-like orphan receptor (Ror) and related-to-receptor tyrosine kinase (Ryk), in the regulation of canonical and non-canonical Wnt signaling pathways, depending on the context; however, the spatiotemporal expression of these genes in relation to Wnt signaling components has not been well characterized in most deuterostome model systems. Here we use a combination of phylogenetic and spatiotemporal gene expression analyses to characterize Ror and Ryk orthologs in sea urchin embryos. Our phylogenetic analysis indicates that both ror1/2 and ryk originated as single genes from the metazoan ancestor. Expression analyses indicate that ror1/2 and ryk are expressed in the same domains of many Wnt ligands and Frizzled receptors essential for the specification and patterning of germ layers along the early anterior-posterior axis. In addition, both genes are co-expressed with Wnt signaling components in the gut, ventral ectoderm, and anterior neuroectoderm territories later in development. Together, our results indicate that Ror and Ryk have a complex evolutionary history and that their spatiotemporal expression suggests that they could contribute to the complexity of Wnt signaling in early sea urchin embryogenesis.

Activities of an ethics consultation service in a Tertiary Military Medical Center.

The Joint Commission on Accreditation of Healthcare Organizations requires hospitals to have a mechanism to address issues of medical ethics. Most hospitals, especially those in the military, have an ethics committee composed solely of members who serve as an additional duty. To enhance the ethics consultation service, the 59th Medical Wing created a position under the chief of the medical staff for a full-time, fellowship-trained, medical ethicist. After establishment of this position, the number of consultations increased, a systematic program for caregiver education was developed and delivered, and an organizational presence was achieved by instituting positions on the institutional review board, the executive committee of the medical staff, and the credentials committee. Issues in medical care are becoming increasingly complicated, due in large part to financial stresses and technological advancements. Ethics consultation can help prevent and resolve many of these problems. This report discusses the activities of the first year of a full-time ethicist in a tertiary military medical center.

Heliox improves pulmonary mechanics in a pediatric porcine model of induced severe bronchospasm and independent lung mechanical ventilation.

BACKGROUND: A helium-oxygen gas mixture (heliox) has low gas density and low turbulence and resistance through narrowed airways. The effects of heliox on pulmonary mechanics following severe methacholine-induced bronchospasm were investigated and compared to those of a nitrogen-oxygen gas mixture (nitrox) in an innovative pediatric porcine, independent lung, mechanical ventilation model. RESULTS: All of the lungs showed evidence of severe bronchospasm after methacholine challenge. Prospective definition of 'heliox response' was a 15% or greater improvement in lung function in the lung receiving heliox compared with the matched lung receiving nitrox. Seven out of 10 pigs responded to heliox therapy with respect to resistance and eight out of 10 pigs responded to heliox therapy with respect to compliance and tidal volume (P < 0.03). After crossover from nitrox to heliox, eight out of eight lungs significantly improved with respect to tidal volume, resistance and compliance (P < 0.001). After crossover from heliox to nitrox all eight lungs showed a significant increase in resistance and a significant decrease in tidal volume (P < 0.001). CONCLUSIONS: In a pediatric porcine model of acute, severe methacholine-induced bronchospasm and independent lung mechanical ventilation, administration of heliox improves pulmonary mechanics, gas flow, and ventilation. Administration of heliox should be considered for support of pediatric patients with acute, severe bronchospasm requiring mechanical ventilation through small artificial airways.

Anesthetic regimen effects on a pediatric porcine model of asphyxial arrest.

The effects of three anesthetic regimens on an established model of pediatric porcine hypoxic-hypercarbic arrest were examined. Twenty-four preadolescent miniature piglets were paralyzed, mechanically ventilated and anesthetized with one of three regimens: IM + IV pentobarbital (n = 8); IM + IV ketamine (n = 8); or IM ketamine+inhaled isoflurane (n = 8). Asphyxial cardiopulmonary arrest was induced and, after and 8 min cardiac arrest nonintervention interval, a standardized protocol of manual CPR with mechanical ventilation was performed. Outcome variables included incidence of ventricular fibrillation, time to cardiac arrest, endogenous plasma epinephrine levels and arteriovenous epinephrine gradients. IV Ketamine anesthesia produced the highest incidence of ventricular fibrillation (P < 0.01 vs. pentobarbital and isoflurane). Time to asphyxia induced cardiac arrest was greatest for the pentobarbital group (P < 0.05 vs. ketamine and isoflurane). During induction of asphyxial cardiac arrest (low cardiac flow), endogenous venous epinephrine accumulation was highest in the pentobarbital anesthetized group (P < 0.05). After 8 min of untreated cardiac arrest and 1 min of CPR (low flow), arterial epinephrine levels were highest in the ketamine group (P < 0.05). Endogenous epinephrine gradients were venous > arterial in all groups at the end of the 8 min cardiac arrest non-intervention interval (no flow). After 1 min of CPR, the gradients had either equalized or reversed to arterial > venous in all groups except for pentobarbital. As designed and expected, return of spontaneous circulation did not occur in any animal. We conclude that, in developing models of porcine asphyxial cardiopulmonary arrest and resuscitation to simulate pediatric human arrest, variations in anesthetic regimen produce significant differences in parameters that are important to consider: time to asphyxia induced cardiac arrest, fibrillation threshold, plasma epinephrine level and arteriovenous epinephrine gradient. Anesthetic effects need to be carefully considered and clearly explained to facilitate the interpretation of studies of interventions in cardiopulmonary arrest and resuscitation.

Mitral valve prolapse and anxiety disorders in patients with anorexia nervosa.

Much has been written about the occurrence of mitral valve prolapse among eating disordered patients. Despite this literature, a causal relationship between the two conditions has yet to be established. The present study evaluated 500 patients with eating disorders and demonstrated an association between a low median ideal body weight and the frequency of mitral valve prolapse (P less than 0.001). The physical signs and symptoms of mitral valve prolapse disappeared in eating disordered patients with the return of normal weight (P less than 0.001). Contrary to prior reports, there was no association between mitral valve prolapse and the occurrence of diagnosable panic or anxiety disorders. The results of this study suggest that the symptoms of anxiety and panic associated with mitral valve prolapse in eating disordered individuals may be due to physiologic change in cardiac status related to weight rather than central nervous system changes associated with classic anxiety disorders.

Sexual abuse in patients with eating disorders.

The incidence of sexual abuse in eating disorder patients appears significant. Fifty percent of both our anorectic and bulimic patients reported a history of sexual abuse while only 28% of a non-anorexic, non-bulimic control population reported similar problems (p less than 0.01). Several patterns of behavior seemed related to previous sexual assault. In one, the eating disorder was used to change the body image of the patient and therefore to provide a defense to future abuse. Other behaviors which occurred more specifically in bulimic women dealt with a projection of repressed anger toward male authority figures. Forty six percent of the bulimic women seen in our study exhibited some promiscuous behavior, using sex either as a gauge of their own self worth or as a means of punishing men. It is essential that sexual issues be addressed early in the treatment of patients with eating disorders. Disclosure is often difficult particularly in outpatient situations where the patient lives at home with her family. It usually does not occur in such cases until the later stages of therapy, or until the patient is hospitalized. Rape is the exception since our data suggests that it is usually revealed early in the course of treatment (p less than 0.001). Once disclosure occurs, a dramatic change is usually seen in the patient and treatment becomes more effective. As the patient deals with the issues of sexual abuse, they no longer need to deny their sexuality or punish themselves or others. Issues of guilt, depression, repressed anger, low self-esteem, social isolation and inadequacy are important and need to be addressed during the course of therapy with sexually abused patients.

Sexual abuse in patients with anorexia nervosa and bulimia.

Few studies have documented the extent and nature of sexual abuse among women who later come to treatment for anorexia nervosa or bulimia. This comparison study reports on a sample of 158 patients admitted to an eating-disorder unit, of whom 60 gave a history of sexual abuse, compared to 98 with no history of abuse. Fifty percent of the anorexic and bulimic patients had suffered sexual abuse, compared to only 28% of patients admitted with other eating-disorder diagnoses; this was a significant difference (p less than 0.001). Of the four types of abuse surveyed, only those patients suffering rape were likely to have sought help from caregivers prior to admission (p less than 0.001). The authors report on likely perpetrators of abuse, age of first abuse, and frequency of depressive symptoms in the abused population. The data from this study strongly suggest that the possibility of sexual assault or abuse must be assessed and the results included in a comprehensive therapy plan for eating-disorder patients.

Identification of mycobacteria from culture by using the Gen-Probe Rapid Diagnostic System for Mycobacterium avium complex and Mycobacterium tuberculosis complex.

Commercially available kits (Mycobacterium avium Complex Rapid Diagnostic System and Mycobacterium tuberculosis Complex Rapid Diagnostic System; Gen-Probe, Inc., San Diego, Calif.) utilizing nucleic acid hybridization for the rapid identification of members of the M. avium-M. intracellulare complex and M. tuberculosis complex were evaluated by using 339 clinical and American Type Culture Collection (Rockville, Md.) isolates. The tests, which can be performed in approximately 2 h, use specific [125I]DNA probes complementary to the rRNAs of M. avium, M. intracellulare, and M. tuberculosis complex, the latter of which includes M. tuberculosis, M. bovis, M. bovis BCG, M. africanum, and M. microti. The M. avium-M. intracellulare probes correctly identified 99 of 114 M. avium-M. intracellulare isolates, with 7 false-negatives and 8 false-positives, for a sensitivity of 93.4% and a specificity of 96.6%. After repeat testing, 110 of 114 were correctly identified, with 4 false-negatives and no false-positives, for a sensitivity of 96.5% and a specificity of 100%. The M. tuberculosis complex probe correctly identified 99 of 102 M. tuberculosis isolates, with 1 false-negative and 2 false-positives, for a sensitivity of 99% and a specificity of 99.2%. After repeat testing, 100 of 102 isolates were correctly identified, with no false-negatives and 2 false-positives, for a sensitivity of 100% and a specificity of 99.2%. Overall, there were 15 discrepant M. avium-M. intracellulare results, with 4 such results after repeat testing, and 3 discrepant M. tuberculosis complex results, with 2 such results after repeat testing. The Gen-Probe kits are highly sensitive and specific for use in identifying M. avium-M. intracellulare complex and M. tuberculosis complex isolates and will be useful in the clinical laboratory which can use the present radionuclide-containing kits cost effectively.

Increasing distance and independence of ambulation in elderly nursing home residents.

We tested the effectiveness of a prompt-and-praise procedure for increasing walking distance and independence in eight nursing home residents. Walking distance and method of ambulation were observed just prior to mealtimes; in addition, mobility and social interaction were time-sampled in the living areas throughout the day. Treatment was lagged in a multiple baseline design across lunch and dinner meals within subjects, and across subjects within each of three units. In the mealtime setting, two subjects began walking the maximum scored distance during baseline; the other six subjects showed a marked increase in walking beginning with the first meal in which the intervention was applied. Six of the eight subjects also progressed to more independent means of ambulation. Generalization of walking to the second meal was observed in all four of the subjects in whom this could be assessed. Generalization across subjects was not observed nor was generalization to the living areas. Staff successfully implemented the procedures in the mealtime settings and the effects were maintained at the 4-month follow-up.

Behavioral covariation in the treatment of delusional verbalization with contingency management.

A 23-year-old female with the dual diagnosis of mild mental retardation and emotional disturbance was referred for treatment because of frequent disruptive outbursts. A brief inpatient behavior analysis suggested that delusional verbalization reliably preceded all other aberrant behaviors. Consequently treatment focused mainly on delusional verbalization; the additional aberrant behaviors were observed for behavioral covariation. The treatment package consisted of verbal instructions, modeling of appropriate eating behaviors, contingent verbal reprimand and a 2-min removal of food, and differential reinforcement of other behaviors. The design was a multiple baseline across settings. Results indicate a marked decrease in delusional verbalization in all settings, and, a correlated decrease for disruption, screaming, and out-of-seat behaviors.

The reduction of seizure-like behaviors through contingency management.

A 22-year-old mildly retarded male, diagnosed as epileptic and paranoid schizophrenic, was admitted to an inpatient behavior unit for a medication assessment and possible behavioral treatment of uncontrolled seizure-like behavior. Since the patient had rarely been allowed out of his living unit in the past year, treatment consisted of a half-hour walk with a preferred staff member made contingent upon a 24-hr period of time free of any occurrence of seizure-like behaviors. An ABAB reversal design was used to assess experimental control. Data indicated that seizures decreased from a mean of 0.70 per day during the initial baseline phase to 0.36 per day during the final treatment phase. Additionally, the duration of seizures decreased from a mean of 50 min per seizure during the initial baseline phase to 17 min per seizure during the final treatment phase, although the contingency was applied irrespective of duration of seizure-like activity. The patient was discharged to a transitional setting until a community placement could be located.

Alteration of tight junctional permeability in the rat parotid gland after isoproterenol stimulation.

The permeability of junctional complexes to ultrastructural tracers of different molecular weight and the freeze-fracture appearance of junctional structure were investigated in the resting and stimulated rat parotid gland. Tracers were administered retrogradely via the main excretory duct, and allowed to flow by gravity (16 mmHg) into the gland for 15-60 min. Secretion was induced in some animals by intraperitoneal injection of isoproterenol. In resting glands, the tracers microperoxidase , cytochrome c, myoglobin, tyrosinase (subunits), and hemoglobin were restricted to the luminal space of the acini and ducts. In glands stimulated 1-4 h before tracer administration, reaction product for microperoxidase , cytochrome c, myoglobin, and tyrosinase was found in the intercellular and interstitial spaces, whereas hemoglobin was usually retained in the lumina. In contrast, horseradish peroxidase and lactoperoxidase appeared to penetrate the tight junctions and reaction product was localized in the extracellular spaces in both resting and stimulated glands. Diffuse cytoplasmic staining for horseradish peroxidase and lactoperoxidase was frequently observed in acinar and duct cells. The distribution of horseradish peroxidase was similar in both Sprague-Dawley and Wistar-Furth rats, and at concentrations of 0.1-10 mg/ml in the tracer solution. Freeze-fracture replicas of stimulated acinar cells revealed an increased irregularity of the tight junction meshwork, but no obvious gaps or discontinuities were observed. These findings indicate that (a) tight junctions in the resting rat parotid gland are impermeable to tracers of molecular weight greater than or equal to 1,900; (b) stimulation with isoproterenol results in a transient increase in junctional permeability allowing passage of tracers of molecular weight less than or equal to 34,500; (c) junctional permeability cannot be directly correlated with junctional structure; and (d) the behavior of horseradish peroxidase and lactoperoxidase in the rat parotid gland is inconsistent with their molecular weights. Cell membrane damage due to the enzymatic activity or binding of these two tracers may account for the observed distribution.

Immunocytochemical localization of catechol-O-methyltransferase in the pregnant rat uterus.

Light microscopic immunocytochemical observations of catechol-O-methyl-transferase (COMT) localization in the pregnant rat uterus were made with a specific antibody to soluble rat liver COMT and the peroxidase-antiperoxidase technique. The changes in cellular localization of COMT were followed from the onset of pregnancy to 12 h after delivery of the last fetus. COMT first appeared on day 5 of pregnancy in endometrial epithelial cells of the uterus. On day 7, COMT appeared in the decidual cells on the antimesometrial side of the uterus close to the implanting blastocyst. Two morphologically distinct, COMT-positive, decidual cells were observed: polygonal cells and stellate cells. After parturition, COMT-positive decidual cells remained in the decidua basalis. The possible physiological roles of COMT in the pregnant uterus are discussed.

Changes in tight junctions of rat intestinal crypt cells associated with changes in their mitotic activity.

The freeze-fracture appearance of tight junctions between rat duodenal crypt cells was studied in normal, mitotically suppressed, and mitotically enhanced animals. In normal animals crypt cell tight junctions present a pleomorphic appearance. The population includes junctions resembling postmitotic junctions of the intestinal villus, junctions composed largely or completely of particle chains, and regions at the cell apex in which junctions are absent for 3-4 micron distances laterally. Mitotic suppression by inhibition of DNA synthesis with cytosine arabinoside results in the disappearance of pleomorphism and crypt tight junctions progressively come to resemble those of the intestinal villus. With recovery from the drug and further synchronization with Colcemid, the crypt cells undergo a mitotic burst, and all varieties of unusual junctional configurations are observed with increased frequency.

Morphology of the granular secretory glands in skin of poison-dart frogs (Dendrobatidae).

The granular glands of nine species of dendrobatid frogs were examined using light and electron microscopy. The glands are surrounded by a discontinuous layer of smooth muscle cells. Within the glands proper the secretory cells form a true syncytium. Multiple flattened nuclei lie at the periphery of the gland. The peripheral cytoplasm also contains mitochondria, rough surfaced endoplasmic reticulum, the Golgi apparatus, and an abundance of smooth endoplasmic reticulum. Centrally, most of the gland is filled with membrane-bound granules surrounded by amorphous cytoplasm. Few other organelles are found in this region. Early in the secretory cycle, the central part of the gland is filled with flocculent material which appears to be progressively partitioned off by membranes to form the droplet anlage. As granules form, the structure of the contents becomes progressively more vesicular. Dense vesicles, which bud off from the Golgi apparatus, fuse with the granular membrane during the development of granules, and might contain enzymes involved in toxin synthesis. The granules at this point resemble multivesicular bodies. Their structure is similar in all species of dendrobatid frogs even though the different frogs secrete substances of different chemical structure and toxicity.