Photocatalytic treatment of organoselenium in synthetic mine-impacted effluents

Biological selenium reduction processes are commonly employed as the best available technology (BAT) for selenium removal; however, as a by-product they produce trace amounts of organoselenium compounds with orders of magnitude greater bioaccumulation potential and toxicity. Here, we assessed buoyant photocatalysts (BPCs) as a potential passive advanced oxidation process (P-AOP) for organoselenium treatment. Using a synthetic mine-impacted water solution, spiked with selenomethionine (96 μg/L) as a representative organoselenium compound, photocatalysis with BPCs fully eliminated selenomethionine to <0.01 μg/L with conversion to selenite and selenate. A theoretical reaction pathway was inferred, and a kinetics model developed to describe the treatment trends and intermediates. Given the known toxic responses of Lepomis macrochirus and Daphnia magna to organoselenium, it was estimated that photocatalysis could effectively eliminate organoselenium acute toxicity within a UV dose of 8 kJ/L (1-2 days solar equivalent exposure), by transformation of selenomethionine to less hazardous oxidized Se species. Solar photocatalysis may therefore be a promising passive treatment technology for selenium-impacted mine water management.

Abstract S5-6: Steroid Hormone Regulation of Mammary Stem Cell Function

Background: The ovarian hormones estrogen and progesterone profoundly influence breast cancer risk, underpinning the benefit of endocrine therapies in the treatment of breast cancer. Modulation of their effects through ovarian ablation or chemoprevention strategies also significantly decreases breast cancer incidence. Conversely, there is an increased risk of breast cancer associated with pregnancy in the short-term. The cellular mechanisms underlying these observations, however, are poorly defined. We and others recently isolated mammary epithelial populations enriched for mammary stem cells (MaSCs), committed luminal progenitor and mature luminal cells from both mouse and human mammary glands. Unexpectedly, MaSCs exhibited a receptor-negative phenotype for ERα , PR and ErbB2. Given the central important of estrogen and progesterone signaling to mammary gland development and cancer, we sought to determine whether these hormones could indirectly modulate MaSC function. Methods and Results: We utilized mouse models to directly study the effects of steroid hormones on the in vivo repopulating ability of MaSCs. Ovariectomy markedly diminished MaSC number and the extent of ductal outgrowth in vivo. The relative contribution of estrogen and progesterone to the regulation of MaSC activity was next examined using hormone pellets or antagonists. MaSC activity increased in animals treated with both estrogen and progesterone. Remarkably, even three weeks of treatment with the aromatase inhibitor letrozole was sufficient to reduce the MaSC pool. The outgrowth potential of these cells was again affected, suggesting that MaSCs retain a ‘memory’ of estrogen deprivation, perhaps through perturbation of their cycling status. Indeed, cell cycle analysis revealed an increase in the percentage of MaSC-enriched cells in G0/G1 in ovariectomized glands compared to controls. This was accompanied by a profound reduction in the expression of cell cycle genes including Cyclin D1.

We further evaluated the effect of the hormonal environment on MaSC function during pregnancy, where progesterone (and prolactin) have prominent roles. Pregnancy led to a transient 11-fold increase in MaSC numbers. This was accompanied by marked elevation in the expression of the progesterone target gene RANK ligand in luminal cells, together with its receptor RANK in the MaSC-containing population. To determine whether MaSC activity is in part mediated through paracrine signals from RANK ligand, inhibitors of RANK signaling were evaluated. Treatment of virgin or pregnant mice with an anti-RANK ligand monoclonal antibody in vivo significantly impaired the clonogenic activity of the MaSC-enriched but not luminal subpopulation.

Discussion: Despite lacking the steroid hormone receptors ERα and PR, MaSCs appear to be exquisitely sensitive to hormone signaling, presumably via paracrine signaling that includes the RANK signaling pathway. The augmented MaSC pool during pregnancy suggests a cellular basis for the short-term increase in breast cancer incidence following pregnancy. Our findings further indicate that breast cancer chemoprevention may in part be achieved through suppression of MaSC function. We speculate that inhibitors of RANK and other stem cell signaling pathways could represent potential chemoprevention agents.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr S5-6.

Functions of alpha-melanotropin and other opiomelanocortin peptides in labour, intrauterine growth and brain development

In a number of animals and in humans, factors from the fetal hypothalamus function in intrauterine growth, in labour and in brain development. Peptides of the opiomelanocortin family are produced by the pituitary, brain and placenta and are probably involved in these developmental processes. In the rat, alpha-MSH stimulates fetal growth, protein synthesis, wound healing and liver regeneration and it reduces periosteal bone resorption. In chick embryos, alpha-MSH restores the corticosteroid-induced growth retardation. Thus alpha-MSH seems to possess general trophic properties. The fetal brain in humans is involved in timing the moment of birth. This process is probably mediated by peptides of the opiomelanocortin family as suggested from observations in anencephaly and other congenital brain anomalies and from the influence of corticosteroids or ACTH on labour. The high percentage of premature deliveries in heroin addicts is worth examining endocrinologically, in this respect. The exact nature of the peptides and mechanisms involved in labour is not yet known. Some peptides of the opiomelanocortin family induce an acceleration of brain development. Neonatal treatment of rats with alpha-MSH alters their later behaviour while ACTH fragments accelerate the onset of eye-opening. Opiates and methadone inhibit brain development, and neonatal administration of beta-endorphin or naloxone causes permanent insensibility to temperature stimuli. The interrelated nature of the fetal pituitary, brain and placenta does not, at present, allow us to pin down which of these structures is primarily involved in the regulation of intrauterine growth, labour and brain development.

Minimally invasive esophagectomy: a teaching hospital's first year experience

Surgical resection of the esophagus remains the mainstay of treatment for esophageal cancer. However, esophagectomy is associated with significant morbidity and mortality in the postoperative period. We have recently altered our practice pattern to include minimally invasive esophagectomy (MIE) as the approach of choice in the hope of minimizing morbidity associated with this procedure. In this retrospective analysis, we compare outcomes of our first year performing MIE to the previous 3 years of open esophagectomy (OE) at a single teaching hospital. Sixty-five patients underwent esophagectomy between June 2002 and July 2006. Among these, 22 patients underwent MIE between June 2005 and July 2006 and 43 patients underwent OE. The two groups were comparable with regards to age, comorbidities and pathologic stage. The MIE group had less operative blood loss (178 mL vs. 356 mL), decreased respiratory complications requiring mechanical ventila-tion (5% vs. 23%), increased number of lymph nodes procured per procedure (15 vs. 8), and increased number of patients discharged within 10 days (72% vs. 28%) when compared to the OE group. No difference was identified in mortality, complications, or length of stay.

Sexual dimorphism in immune function: the role of prenatal exposure to androgens and estrogens

Perinatal exposure to androgens permanently transforms certain tissues, e.g., the brain, the genitalia, etc. This process involves both masculinization and defeminization. Immune function also is transformed by early steroid exposure; however, it is not yet known whether the response capabilities of the immunocytes themselves are directly modified or whether they are responding to signals from other masculinized tissues, e.g., the brain. Most evidence points to a direct effect since androgen and estrogen receptors are present in developing immunocytes. Both androgens and estrogens have a role in regulating adult immunity including Th1/Th2 balance. Adult susceptibility to autoimmune and other diseases is also related to steroid exposure. How immune cells respond to gonadal steroids in adulthood may depend on the pattern of androgenic and estrogenic stimulation during early development.

Positioning aged patients

While geriatric patients do not present problems of positioning that are found only in their age group, their acquired infirmities may intensify the likelihood and severity of complications common to younger peers. Careful preoperative evaluation of potential positioning problems is needed, as is explicit recording of positioning recommendations in a manner easily encountered by appropriate members of the care team. The physiologic impact of those infirmities that are present upon the ability of the patient to recover from the surgical and anesthetic experience should be kept clearly in mind throughout the procedure, and techniques involved should be modified accordingly. A postoperative survey of potential complications of positioning should be made expeditiously to permit indicated treatment to be applied rapidly to an elderly patient.

Analysis of rapid maxillary molar distal movement without patient cooperation

The purpose of this investigation was to evaluate the treatment effects of an intraoral appliance used for rapid distal movement of the maxillary molars. The appliance studied, the Jones jig, is designed to deliver a distalizing force to the maxillary molar against an intraoral anchorage unit thereby eliminating the need for patient compliance. A retrospective study was performed comparing before and after lateral cephalometric radiographs on 13 patients who were treated for an average of 26 weeks with the Jones jig. The cephalometric radiographs were evaluated to determine if there were significant differences between pretreatment and posttreatment variables that included skeletal, dental and soft tissue relationships. Differences between the pretreatment and posttreatment means were significant for mesial angulation of the premolar anchorage unit (P <.001), distal movement of the maxillary molars (P <.01), mesial movement of the premolar anchorage unit (P <. 01), mesial movement of the maxillary incisors (P <.001), and increased lower anterior facial height (P <.01). The anchorage loss, flared maxillary incisors, and increased facial height are negative treatment effects that should be expected when using this or similar appliance design.

A numerical study of radiofrequency deposition in a spherical phantom using surface coils

The electromagnetic fields induced by a surface coil in a spherical phantom, having a wide range of electrical properties, is studied using numerical methods of calculation. The specific absorption rate (SAR), radiofrequency magnetic field (B1), magnetic field energy within the phantom (EB), and the volume-averaged SAR (<SAR>) are calculated at 10, 63, and 200 MHz. They are analyzed with respect to dielectric constant, wavelength, and skin depth effects, which become increasingly important in high field magnetic resonance imaging (MRI) where safety and field homogeneity issues need further study. Particular attention is given to solutions representing neural tissue at each frequency. In general, the <SAR> data at high field strengths have local maxima, with a quasi-harmonic behavior, when the following two resonant conditions are satisfied: 1) skin depth becomes comparable to, or larger than, the sample diameter Ds; and 2) Ds is near an integral multiple of the wavelength. These are also the solutions with maximum EB values and the least homogeneous B1. Samples undergoing resonance at 200 MHz are shown to have important off-axis B1 maxima (affecting field homogeneity) and large <SAR> values. Some non-resonating 200-MHz phantoms, including simulations consistent with neural tissue, contain larger SAR maxima than the resonating samples, posing safety concerns in high field imaging of biologic tissue.

Development of an adjuvant to enhance the immune response to influenza vaccine in the elderly

Elderly persons typically show diminished immune responsiveness to influenza vaccination. Chiron Vaccines has developed a novel oil-in-water adjuvant emulsion, MF59, to enhance vaccine immunogenicity without compromising safety and tolerability. MF59 was shown to augment influenza vaccine immunogenicity in senescent mice. Subsequently, eight similarly designed, randomized, controlled clinical trials of a subunit influenza vaccine combined with MF59 were conducted between 1992 and 1995 in 1807 elderly volunteers (> or = 65 years old). Mild, transient, injection-site reactions were increased with MF59, but systemic reactions generally were not. For two of the three vaccine antigens (B and A/H3N2), postimmunization haemagglutinin inhibition geometric mean titres were statistically significantly higher with MF59. During influenza season, fewer deaths occurred among MF59 recipients. This development programme demonstrates how an adjuvant that stimulates effectors associated with immunosenescence can improve the performance of an existing vaccine in elderly persons.

The Trendelenburg position: a review of current slants about head down tilt

The steep head down tilt surgical posture, popularized in the 1870s by Trendelenburg as a means of improving access to pelvic pathology and espoused by the American physiologist, Walter Cannon, during World War I as a resuscitative position with which to treat shock, has a history of widespread, ritualistic acceptance. An awake patient placed in steep head down tilt usually objects to the posture after only a short time. Now recognized as potentially harmful in the presence of cardiac, pulmonary, ocular, and central nervous system pathology and essentially useless for vascular resuscitation, steep tilt should be limited to selected circumstances in which alternatives are unacceptable. Shallow head down tilt, a more recent variety, also offers serious questions about its surgical usefulness as well as its applicability for patients with diseased hearts, lungs, and heads. As an aid to resuscitative procedures, the contoured supine position offers assets that merit serious consideration. Means of restraining a tilted patient on an operating table include wristlets, shoulder braces, and bent knees with ankle restraints. Considerations that aid in the selection of head down tilt are presented, as is a plea for the abandonment of the Trendelenburg eponym and a suggestion for future investigation.

Ulnar neuropathy. Incidence, outcome, and risk factors in sedated or anesthetized patients

BACKGROUND

Ulnar neuropathy is well-recognized as a potential complication of procedures performed on anesthetized patients. However, reported outcomes and risk factors for this problem are based on small series and anecdotes.

METHODS

We retrospectively reviewed the perioperative courses of 1,129,692 consecutive patients who underwent diagnostic and noncardiac surgical procedures with concurrent anesthetic management at the Mayo Clinic from 1957 through 1991 (inclusive). The medical diagnoses of patients who had these procedures were scanned for 26 diagnoses associated with neuropathy. Persistent neuropathy of an ulnar nerve was defined as a sensory or motor deficit of greater than 3 months' duration. Risk factors anecdotally associated with persistent neuropathy were analyzed by comparing patients with an ulnar neuropathy with control subjects in a 1:3 case-control study.

RESULTS

Persistent ulnar neuropathies were identified in 414 patients, a rate of 1 per 2,729 patients. Of these, 38 (9%) patients had bilateral neuropathies. Approximately equal numbers of the neuropathies included sensory loss only or mixed sensory and motor loss. Initial symptoms form most neuropathies were noted more than 24 h after the procedure. Factors associated with persistent ulnar neuropathy included male gender and a duration of hospitalization of more than 14 days (P < 0.01). Neuropathy was more likely to develop in very thin and obese patients than in patients with average body habitus. Neither the type of anesthetic technique nor the patient position was found to be associated with this neuropathy. Of the 382 patients who survived the 1st postoperative yr, 53% regained complete motor function and sensation and were asymptomatic. Of those with neuropathies persisting for more than 1 yr, most had moderate or greater disability from pain or weakness.

CONCLUSIONS

These data suggest that perioperative ulnar neuropathies are associated with factors other than general anesthesia and intraoperative positioning. Men at the extremes of body habitus who have prolonged hospitalizations are particularly susceptible to development of ulnar neuropathies.

Lower-extremity motor neuropathy associated with surgery performed on patients in a lithotomy position

BACKGROUND

Motor neuropathy of a lower extremity is well-recognized as a potential complication of procedures performed on patients in a lithotomy position. Most of this awareness is based on anecdotal reports, however, and the incidence and risk factors for this complication have not been reported.

METHODS

We retrospectively reviewed the perioperative courses of 198,461 consecutive patients who underwent 1 of 56 surgical procedures historically performed on patients in a lithotomy position at the Mayo Clinic, Rochester, Minnesota, from 1957 to 1991 inclusive. The medical diagnoses of patients who had procedures in a lithotomy position were scanned for 26 diagnoses associated with neuropathy. Persistent neuropathy of the lower extremity was defined as a motor deficit of at least 3 months' duration. Risk factors anecdotally associated with persistent neuropathy were analyzed by comparing identified cases of neuropathy to controls in a 1:3 case-control study.

RESULTS

Persistent neuropathies after procedures performed on patients in a lithotomy position were identified in 55 cases for a rate of 1 per 3,608. Multivariate risk factors for development of a persistent neuropathy of a lower extremity included duration in lithotomy of 4 h or longer, a body mass index (kilograms per squared meter) of 20 or less, and a history of smoking within 30 days of the procedure. Regional anesthetic techniques were not found to be associated with an increased risk of neuropathy. Of the 53 patients who lived at least 1 yr after their procedure, 24 (45%) required either prosthetic or ambulatory support for persistent foot drop or leg weakness.

CONCLUSIONS

These data suggest that prolonged duration in lithotomy and patient risk factors, including very thin body habitus and smoking in the preoperative period, are associated with the development of a lower-extremity neuropathy after procedures performed on patients in a lithotomy position. A reduction of time in the lithotomy position may be particularly worthwhile for patients with these risk factors.

Shame and the origin of physician-patient conflict

Shame is a powerful negative emotion that motivates much intrapersonal and interpersonal conflict. The relationship between patient and physician can turn to conflict if the medical environment elicits shame in the patient; conflict arises when the patient externalizes the cause and blames the physician for negative feelings. Patients who suffer from hyperactive and reactive shame responses may require particularly sensitive care. Including the assessment of shame reactivity in the medical history can help identify such persons. Measures that reduce shame should improve compliance and reduce the incidence of malpractice suits.

New head-prone position for posterior fossa surgery in infants with severe hydrocephalus

A new head-prone position is described for posterior cranial fossa surgery on infants whose cerebral cortical mantle has been markedly thinned by severe hydrocephalus. The new position furnished a direct line of sight to the apex of the IV ventricle corresponding to that provided by the classic high sitting position, without the latter's risks of air embolism and of acute subdural hematoma secondary to tearing of corticodural bridging vessels due to escape of gravity-impelled CSF from the large ventricles. The anesthesiologic technique, the positioning of the patient, and the surgeon's posture presented no unusual problems.

Analysis of contributing factors to the occurrence of off-focus radiation (OFR)

Off-focus radiation (OFR) has previously been described by many investigators [R. Thoraeus, Acta Radiologica 18, 753 (1937); L. Mallet and R. Maurin, Radiology 48, 628-632 (1947); J. F. Timmer, Medicamundi 19(2), 52-54 (1974); G. U. Rao, Appl. Radiol. 3(3), 45-49 (1974); R. Birch, Br. J. Radiol. 49, 951-955 (1976); W. W. Roeck, AAPM Symposium, 217-247 (1991)]. Off-focus radiation is frequently manifested on radiographs by the appearance of faint images of anatomical structures outside the collimated field of interest, i.e., soft tissues, ear lobes and hair, which we will refer to as "penumbral images." The observable small detail resolution within these penumbral images led to the assumption that minute sources of increased radiation intensity (secondary microfocal spots) must be present outside the area of the primary focal spot. The existence of these multiple secondary microfocal spots has been established and their locations within the area of the anode surface from which the general OFR originates was identified. The number, size, and distribution of the secondary focal spots vary over time and their magnitudes vary widely. The source of the well-focused electron beams creating the spots is attributed to the cold cathode emission principle.

A rapid in vitro test for chloroquine-resistant Plasmodium falciparum

We report a rapid (2-3 hr) in vitro test for chloroquine resistance in Plasmodium falciparum. The test is based on the inhibition of chloroquine efflux by verapamil; it is performed by diluting infected blood in culture medium and incubating the diluted blood for 60 min at 37 degrees C with 50 nM 3H-chloroquine, with and without 10 microM verapamil. The test can be performed with the ring stage parasites in the blood of infected patients and in the presence of white cells, platelets and anticoagulants (heparin, EDTA, or citrate). Although the test can be performed in triplicate with 20 microliters of blood and specimens may be kept in anticoagulants at 4 degrees C for up to 24 hr, parasitemias less than 0.1% limit the sensitivity of the assay. Inhibition of chloroquine efflux by verapamil may permit the rapid identification of chloroquine resistant P. falciparum in blood specimens from infected patients.

Refractory congestive heart failure after ribavirin in infants with heart disease and respiratory syncytial virus

Although treatment with ribavirin has been known to be associated with a decreased mortality in infants with congenital heart disease (CHD) who have respiratory syncytial virus (RSV), few data are available regarding morbidity. We reviewed records of 10 consecutively hospitalized infants with CHD during a recent RSV epidemic. Despite the presence of left-to-right shunt in each patient, symptoms of RSV were respiratory at presentation. After ribavirin, decreased respiratory symptoms were found in 8 infants but in 2 assisted ventilation were required 1 and 3 days after admission. Congestive heart failure worsened in 8 patients, 6 of whom had improved respiratory status after ribavirin. Of the 8 patients with worse CHF (pulmonary edema), 3 responded to medical management but 5 were refractory and 4 required surgical repair of CHD. One patient died of pulmonary hemorrhage. Medically refractory CHF may develop in infants with CHD who become infected with RSV and are treated with ribavirin. Further studies are needed to determine whether the pulmonary edema is caused by RSV, ribavirin, or combination of effects on pulmonary capillary function or some other unrecognized mechanism.

Postoperative isolated dysfunction of the long thoracic nerve: a rare entity of uncertain etiology

A "winged" scapula is a rare, poorly understood, and potentially disabling curiosity following anesthesia and surgery. It is produced by dysfunction of the long thoracic nerve and consequent paralysis of the serratus anterior muscle. A survey of senior anesthesiologists indicated a consistent lack of familiarity with the entity. This article presents six cases of postoperative long thoracic nerve palsy. In a literature review of 111 instances of long thoracic nerve palsy, 51 were trauma-related, 47 were either idiopathic or of debatable origin, and 13 appeared following a surgical or obstetrical procedure. Unprovable etiologic contentions were frequent. Considerations of the etiologies of postoperative long thoracic nerve palsies must include a coincidental infectious neuropathy ("neuralgic amyotrophy") as a valid alternative to the assertion that a preventable injury occurred during anesthesia.

Massive intraoperative atelectasis secondary to untreated mediastinal Hodgkin's disease: report of the hazard and review of the literature

Mediastinal adenopathy in Hodgkin's disease has been known to cause relative airway compromise, particularly in the more vulnerable left mainstem bronchus. This has been infrequently reported to occur during general anesthesia and to cause respiratory embarrassment, representing a significant hazard. The possibility of its occurrence should be recognized. Preoperative evaluation of the airway by chest films and tomography, followed by radiation therapy in those patients at risk, is recommended to minimize the chances of respiratory complications during general anesthesia.

Development of a tracheal implant xenograft model to expose human bronchial epithelial cells to toxic gases

A tracheal implant model was developed which enabled exposure of differentiated normal human bronchial epithelial cells (NHBE) to a single exposure of a model toxic gas (formaldehyde). NHBE cells were grown in vitro in explant culture under defined serum-free conditions from previously frozen bronchial segments, harvested, and used to repopulate de-epithelialized rabbit tracheas. Rabbit tracheal segments repopulated with NHBE cells were implanted into the subcutis of congenitally athymic nude mice. Following graft vascularization, the xenografted NHBE cells differentiated and formed a mucociliary epithelial surface which lined approximately 50% of the surface of the implant lumen. Eight weeks post-implantation both ends of the implanted grafts were cannulated, and formaldehyde (HCHO) vapor (0, 6, or 15 ppm) in humidified air was passed through the tracheal lumens. Representative epithelial surfaces were examined by light and scanning electronmicroscopy, and autoradiography prior to, immediately after, and 48 hr following a 1-hr exposure to the test vapors. Light microscopic examination of implant sections immediately following exposure to 6 and 15 ppm HCHO detected cessation of ciliary activity, which recovered by 48 hr post-exposure. Scanning electron microscopic examination of the epithelial surface demonstrated mild morphologic changes, restricted to those implants exposed to 15 ppm. Findings immediately following HCHO exposure included swelling and exfoliation of individual cells, deciliation, and mucus release. Changes present after 48 hr included presence of flattened cells with few short microvilli and focal increase in the number of S-phase nuclei in the basal epithelium. These results demonstrate the utility of tracheal implants for single short-term exposure of differentiated human bronchial epithelial cells to gaseous agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-melanocyte-stimulating hormone infusions during pregnancy in the rat: effects on offspring weight, pain reactivity and sexual behavior

Pregnant rats treated during the last third of pregnancy with a continuous infusion of alpha-melanocyte-stimulating hormone (alpha-MSH) produced offspring that weighed less at birth and in adulthood. These offspring of the alpha-MSH treated mothers were less sensitive to pain and as adults showed a reduced analgesic response to morphine. Male offspring of alpha-MSH treated mothers and of control animals responded similarly in sexual performance tests, except that the treated animals significantly shifted their pattern of responding when they encountered a new testing arena or experienced defeat. The offspring of alpha-MSH treated mothers were influenced more by changes in their environment than were control offspring. These effects are similar to those reported following perinatal treatment with opiate drugs or peptides.

Low-level, magnetic-field-induced growth modification of Bacillus subtilis

Experimental studies showed an increase in the growth of Bacillus subtilis mutant strain FJ7 above controls by exposing the bacterial culture to 800-Hz or 1-KHz magnetic fields with a 2-s-on/2-s-off period. The magnetic field strength was between 0.8 and 2.5 mT. Light microscopy and scanning electron microscopy demonstrated the morphology of controls to grow in a macrofiber of right-handed helix formation. In contrast, the field-exposed group showed little to no cohesion; the cells appeared to be homogeneously distributed throughout the sample. These results suggest that growth patterns of Bacillus subtilis can be altered as a result of magnetic-field-induced effects.

Neonatal exposure of female ferrets to testosterone alters sociosexual preferences in adulthood

Sociosexual preferences in adult female ferrets, as measured in a choice arena, were altered by neonatal exposure to exogenous testosterone. Adult female ferrets showed a preference for males which did not depend on the presence of gonadal steroids, because gonadectomized and gonadectomized estrogen-treated females showed identical preferences for males. Adult castrated males showed no preference for females unless these males were treated with testosterone. A similar no-preference pattern was found in adult females that had received testosterone neonatally. Females exposed neonatally to dihydrotestosterone or estradiol exhibited the normal females' male-oriented preference. These results indicate that testosterone secreted by the testes in the developing male may interrupt the phenotypic female development pattern and hence prevent the emergence of a homosexual preference in adulthood in the male ferret.

Surface topography and distribution of cell types in the rat nasal respiratory epithelium: scanning electron microscopic observations

Several cell types were identified in the rat nasal respiratory epithelium using scanning electron microscopy. In addition to the previously described ciliated, nonciliated, and goblet cells, the nasal brush cell was identified based on its surface characteristics and its location between nonciliated epithelial cells. Scanning electron microscopy clearly showed the differences in distribution of cell types in the nasal mucosa. The ciliated cells increase in number from the anterior to the posterior areas of the respiratory epithelium with a corresponding decrease in nonciliated cells. However, even at a single cross-sectional area of the nasal cavity, the various surfaces have different proportions of ciliated versus nonciliated cells, e.g., the medial surface of the nasal concha has more ciliated cells than other surfaces. Brush cells are distributed between nonciliated cells of the respiratory epithelium on most surfaces of the nasal cavity including the conchae and the lateral wall. Based on the available information, scanning electron microscopy will be useful in future studies to determine the effects that inhaled toxicants have on cells and on the location of lesions.

Differentiated features of a transformed epithelial cell line (TRKE-1) derived from dimethylnitrosamine-treated rat kidney

TRKE-1 is a pure line of epithelium-like neoplastic cells derived from the kidney of a rat treated 48 hr previously with a carcinogenic dose of dimethylnitrosamine. Using light microscopy, the line was characterized by cohesive growth behavior typical for epithelium and the formation of hemicysts (domes) at postconfluence. Enhancement of dome formation by dibutyryl cyclic adenosine 3':5'-monophosphate and dimethyl sulfoxide and inhibition by ouabain established these structures as a manifestation of differentiated cellular function, namely, transepithelial fluid transport. Structurally, TRKE-1 cells in monolayer culture were characterized by apical distribution of microvilli, cilia, and endocytic vesicles, ordered sequence of junctional components at the apical lateral border including tight junction and desmosomes, basolateral cellular interdigitations below the junctional complex, basal location of microfilament bundles, and a conspicuous content of mitochondria. Each of these features typifies mammalian renal tubule epithelium in vivo. The occasional profusion of microvilli; the prominent, apically distributed endocytic vesicles; and the well-developed basal microfilament tracts suggest, in particular, that the proximal segment of the nephron may represent the site of origin of this transformed cell line. The various morphological aspects of renal epithelial differentiation were also expressed in multicellular tumor spheroids grown in suspension, with an accentuation of junctional complexes, endocytic vesicles, and intracytoplasmic lumina. In addition, this three-dimensional culture mode supported cellular organization into acinar profiles suggestive of primitive tubule formation. In confirming the epithelial nature of TRKE-1 and a possible identity with the proximal tubule, this study provides an in vitro animal model representative of chemically transformed renal epithelium which may be analogous to human renal cell carcinoma.

Succinylcholine-induced increases in plasma catecholamine levels in humans

Given the hypothesis that interaction of succinylcholine with nicotinic receptors releases endogenous catecholamines, plasma levels of epinephrine and norepinephrine were determined in anesthetized and manually ventilated patients immediately before and 2 min after intravenous administration of succinylcholine. Anesthesia was induced with intravenous thiopental (3-4 mg/kg) followed by the administration of nitrous oxide and oxygen (1:1) and 0.5-1.0% halothane. Stimulation of the patients was avoided. Succinylcholine (1 mg/kg) or metocurine (0.3 mg/kg) was injected intravenously and ventilation was controlled without intubation. Plasma norepinephrine levels increased from 301 pg/ml to 491 pg/ml (SEM = +/- 19 pg/ml, P less than 0.01, N = 5) 2 min after the injection of succinylcholine; the increase in plasma epinephrine was not statistically significant. The time course of catecholamine elevation was studied in three additional patients. The increase of norepinephrine occurred immediately after the injection of succinylcholine, peaked (647 +/- 67 pg/ml) around the third minute, and disappeared by the 10th min. The increase in epinephrine was less marked. Plasma levels of catecholamines did not change after the injection of metocurine (N = 2). The possibility that succinylcholine stimulates nicotinic receptors on the postganglionic sympathetic terminals is discussed. We propose that the elevation of plasma norepinephrine might contribute to the development of early adverse cardiovascular reactions to succinylcholine.