Functional heartburn has more in common with functional dyspepsia than with non-erosive reflux disease

INTRODUCTION: Functional dyspepsia and non-erosive reflux disease (NERD) are prevalent gastrointestinal conditions with accumulating evidence regarding an overlap between the two. Still, patients with NERD represent a very heterogeneous group and limited data on dyspeptic symptoms in various subgroups of NERD are available. AIM: To evaluate the prevalence of dyspeptic symptoms in patients with NERD subclassified by using 24 h impedance-pH monitoring (MII-pH). METHODS: Patients with typical reflux symptoms and normal endoscopy underwent impedance-pH monitoring off proton pump inhibitor treatment. Oesophageal acid exposure time (AET), type of acid and non-acid reflux episodes, and symptom association probability (SAP) were calculated. A validated dyspepsia questionnaire was used to quantify dyspeptic symptoms prior to reflux monitoring. RESULTS: Of 200 patients with NERD (105 female; median age, 48 years), 81 (41%) had an abnormal oesophageal AET (NERD pH-POS), 65 (32%) had normal oesophageal AET and positive SAP for acid and/or non-acid reflux (hypersensitive oesophagus), and 54 (27%) had normal oesophageal AET and negative SAP (functional heartburn). Patients with functional heartburn had more frequent (p<0.01) postprandial fullness, bloating, early satiety and nausea compared to patients with NERD pH-POS and hypersensitive oesophagus. CONCLUSION: The increased prevalence of dyspeptic symptoms in patients with functional heartburn reinforces the concept that functional gastrointestinal disorders extend beyond the boundaries suggested by the anatomical location of symptoms. This should be regarded as a further argument to test patients with symptoms of gastro-oesophageal reflux disease in order to separate patients with functional heartburn from patients with NERD in whom symptoms are associated with gastro-oesophageal reflux.

Generation and characterization of antigenic variants induced by exposure of tumor cells to UV radiation in vitro

Antigenic changes present in nonantigenic tumor cells exposed to UV radiation (UV) in vitro were investigated by addressing the following questions: (1) Are antigenic variants (AV) produced that are rejected in normal but not immunosuppressed mice? (2) Does generation of AV depend upon intrinsic properties of the cells exposed or result from the action of UV? (3) Is antigenic modification induced by UV due to increased histocompatibility antigen expression? (4) Do AV crossreact immunologically with parental tumor or with other AV? and (5) Is the UV-associated common antigen expressed on UV-induced tumors present on UV-irradiated tumor cells? AV were generated at different frequencies following in vitro UV irradiation of a spontaneous murine fibrosarcoma (51% of cell lines tested), a murine melanoma (56%), and two melanoma clones (100% and 11%). This indicated that the percentage of AV produced is an intrinsic property of the cell line exposed. The increased antigenicity did not correlate with an increased expression of class I histocompatibility antigens. Immunological experiments demonstrated that the AV and parental cells shared a determinant that was susceptible to immune recognition, but incapable of inducing immunity. In contrast, the AV were noncrossreactive, suggesting that variant-specific antigens were also expressed. Finally, the AV were recognized by UV-induced suppressor cells, indicating that the UV-associated common antigen expressed by UV-induced tumors was also present. This investigation provides new information on the susceptibility of tumors to antigenic modification by UV and on the relationship between tumor antigens and neoplastic transformation. Furthermore, it suggests an immunological approach for cancer therapy. ^

Gastro-oesophageal reflux is common in oligosymptomatic patients with dental erosion: A pH-impedance and endoscopic study.

Background: Dental erosion is a complication of gastro-oesophageal reflux disease (GORD) according to the Montreal consensus statement. However, GORD has not been comprehensively characterized in patients with dental erosions and pH-impedance measures have not been reported. Objectives: Characterize GORD in patients with dental erosions using 24-h multichannel intraluminal pH-impedance measurements (pH-MII) and endoscopy. Methods: This single-centre study investigated reflux in successive patients presenting to dentists with dental erosion using pH-MII and endoscopy. Results: Of the 374 patients, 298 (80%) reported GORD symptoms <2 per week, 72 (19%) had oesophagitis and 59 (16%) had a hiatal hernia. In the 349 with pH-MII the mean percentage time with a pH <4 (95% CI) was 11.0 (9.3–12.7), and 34.4% (31.9–36.9) for a pH <5.5, a critical threshold for dental tissue. The mean numbers of total, acidic and weakly acidic reflux episodes were 71 (63–79), 43 (38–49) and 31 (26–35), respectively. Of the reflux episodes, 19% (17–21) reached the proximal oesophagus. In 241 (69%) patients reflux was abnormal using published normal values for acid exposure time and reflux episodes. No significant associations between the severity of dental erosions and any reflux variables were found. The presence of GORD symptoms and of oesophagitis or a hiatal hernia was associated with greater reflux, but not with increased dental erosion scores. Conclusions: Significant oligosymptomatic gastro-oesophageal reflux occurs in the majority of patients with dental erosion. The degree of dental erosion did not correlate with any of the accepted quantitative reflux indicators. Definition of clinically relevant reflux parameters by pH-MII for dental erosion and of treatment guidelines are outstanding. Gastroenterologists and dentists need to be aware of the widely prevalent association between dental erosion and atypical GORD.

Common target genes of palatal and gingival fibroblasts for EMD: the microarray approach.

BACKGROUND AND OBJECTIVE Connective tissue grafts are frequently applied, together with Emdogain(®) , for root coverage. However, it is unknown whether fibroblasts from the gingiva and from the palate respond similarly to Emdogain. The aim of this study was therefore to evaluate the effect of Emdogain(®) on fibroblasts from palatal and gingival connective tissue using a genome-wide microarray approach. MATERIAL AND METHODS Human palatal and gingival fibroblasts were exposed to Emdogain(®) and RNA was subjected to microarray analysis followed by gene ontology screening with Database for Annotation, Visualization and Integrated Discovery functional annotation clustering, Kyoto Encyclopedia of Genes and Genomes pathway analysis and the Search Tool for the Retrieval of Interacting Genes/Proteins functional protein association network. Microarray results were confirmed by quantitative RT-PCR analysis. RESULTS The transcription levels of 106 genes were up-/down-regulated by at least five-fold in both gingival and palatal fibroblasts upon exposure to Emdogain(®) . Gene ontology screening assigned the respective genes into 118 biological processes, six cellular components, eight molecular functions and five pathways. Among the striking patterns observed were the changing expression of ligands targeting the transforming growth factor-beta and gp130 receptor family as well as the transition of mesenchymal epithelial cells. Moreover, Emdogain(®) caused changes in expression of receptors for chemokines, lipids and hormones, and for transcription factors such as SMAD3, peroxisome proliferator-activated receptor gamma and those of the ETS family. CONCLUSION The present data suggest that Emdogain(®) causes substantial alterations in gene expression, with similar patterns observed in palatal and gingival fibroblasts.

Assessing homogeneity in workplace exposure under stationary and non-stationary scenarios

In most epidemiological studies, historical monitoring data are scant and must be pooled to identify occupational groups with homogeneous exposures. Homogeneity of exposure is generally assessed in a group of workers who share a common job title or work in a common area. While published results suggest that the degree of homogeneity varies widely across job groups, less is known whether such variation differs across industrial sectors, classes of contaminants, or in the methods used to group workers. Relying upon a compilation of results presented in the literature, patterns of homogeneity among nearly 500 occupational groups of workers were evaluated on the basis of type of industry and agent. Additionally, effects of the characteristics of the sampling strategy on estimated indicators of homogeneity of exposure were assessed. ^ Exposure profiles for occupational groups of workers have typically been assessed under the assumption of stationarity, i.e., the mean exposure level and variance of the distribution that describes the underlying population of exposures are constant over time. Yet, the literature has shown that occupational exposures have declined in the last decades. This renders traditional methods for the description of exposure profiles inadequate. Thus, work was needed to develop appropriate methods to assess homogeneity for groups of workers whose exposures have changed over time. A study was carried out applying mixed effects models with a term for temporal trend to appropriately describe exposure profiles of groups of workers in the nickel-producing industry over a 20-year period. Using a sub-set of groups of nickel-exposed workers, another study was conducted to develop and apply a framework to evaluate the assumption of stationarity of the variances in the presence of systematic changes in exposure levels over time. ^

The effect of exposure to antibiotics on incidence and spontaneous clearance of childhood Helicobacter pylori infection

It is claimed often in the H. pylori literature that spontaneous clearance (infection loss without attempts to treat) is uncommon, though little evidence supports this claim. Emerging evidence suggests that spontaneous clearance may be frequent in young children; however, factors that determine persistence of untreated H. pylori infection in childhood are not well understood. The author hypothesized that antibiotics taken for common infections cause spontaneous clearance of H. pylori infection in children. The Pasitos Cohort Study (19982005) investigated predictors of acquisition and persistence of H. pylori infection in children from El Paso, Texas, and Juarez, Mexico, enrolled prenatally at maternal-child clinics. Children were screened for infection at target intervals of 6 months from 6-84 months of age by the 13C-urea breath test corrected for body-size-dependent variation in CO2 production. This dissertation aimed to estimate the risk of spontaneous clearance at the next test following an initial detected H. pylori infection (first detected clearance), estimate the effect of antibiotic exposure on the risk of first detected clearance (risk difference), and estimate the effect of antibiotic exposure on the rate of first detected infection (rate ratio). Data on infection status and medication history were available for 608 children followed for a mean of 3.5 years. Among 265 subjects with a first detected infection, 218 had a subsequent test, and among them, the risk of first detected clearance was 68% (95% CI: 61-74%). Children who took antibiotics during the interval between first detected infection and next test had an increased probability (risk difference of 10 percentage points) of a first detected clearance. However, there was also a similar effect of average antibiotic use >0 courses across all intervals preceding the next test. Average antibiotic exposure across all intervals preceding the first detected infection appeared to have a much stronger protective effect than interval/specific exposure when estimating incidence rate ratios (0.45 vs. 1.0). Incidental antibiotic exposure appears to influence the acquisition and duration of childhood H. pylori infection, however, given that many exposed children acquired the infection and many unexposed children cleared the infection, antibiotic exposure does not explain all infection events. ^

Genetic susceptibility, cigarette smoking, and wood dust exposure in lung cancer: Case control analyses

This case control study was conducted to assess the association between lung cancer risk, mutagen sensitivity (a marker of cancer susceptibility), and a putative lung carcinogen, wood dust exposure. There were 165 cases (98 African-Americans, 67 Mexican-Americans) with newly diagnosed, previously untreated lung cancer, and 239 controls, frequency-matched on age, sex, and ethnicity.^ Mutagen sensitivity ($\ge$1 break/cell) was associated with a statistically significant elevated risk for lung cancer (odds ratio (OR) = 4.1, 95% confidence limits (CL) = 2.3,7.2). Wood dust exposure was also a significant predictor of risk (OR = 2.8, 95% CL = 1.2,6.6) after controlling for smoking and mutagen sensitivity. When stratified by ethnicity, wood dust exposure was a significant risk factor for African-Americans (OR = 4.0, 95% CL = 1.4,11.5), but not for Mexican-Americans (OR = 1.5, 95% CL = 0.3,7.1). Stratified analysis suggested a greater than multiplicative interaction between wood dust exposure and both mutagen sensitivity and smoking.^ The cases had significantly more breaks on chromosomes 4 and 5 than the controls did with ORs of 4.9 (95% CL = 2.0, 11.7) and 3.9 (95% CL = 1.6, 9.3), respectively. Breaks at 4p14, 4q27, 4q31, 5q21-22, 5q31, and 5q33 were significantly more common in lung cancer patients than in controls. Lung cancer risk had a dose-response relationship with breaks on chromosomes 4 and 5. Cigarette smoking had a strong interaction with breaks on chromosomes 2, 4, and 5.^ In a molecular cytogenetic study, using chromosome painting and G-banding, we showed that: (1) the proportion of chromosome 5 abnormalities surviving as chromosome-type aberrations remained significantly higher in cells of lung cancer cases (14%) than in controls (5%) (P $<$ 0.001). However, no significant differences were detected in chromosome 4 abnormalities between cases and controls; (2) the proportion of chromosome 5q13-22 abnormalities was 5.3% in the cases and 0.7% in the controls (P $<$ 0.001). 5q13-22 regions represented 40% of all abnormalities on chromosome 5 in the cases and only 14% in the controls.^ This study suggests that mutagen sensitivity, wood dust exposure, and cigarette smoking were independent risk factors for lung cancer, and the susceptibility of particular chromosome loci to mutagenic damage may be a genetic marker for specific types of lung cancer. ^

Exposure to nonsteroidal anti-inflammatory drugs and weight loss and hospitalization in non-small cell lung cancer patients

Background. Cancer cachexia is a common syndrome complex in cancer, occurring in nearly 80% of patients with advanced cancer and responsible for at least 20% of all cancer deaths. Cachexia is due to increased resting energy expenditure, increased production of inflammatory mediators, and changes in lipid and protein metabolism. Non-steroidal anti-inflammatory drugs (NSAIDs), by virtue of their anti-inflammatory properties, are possibly protective against cancer-related cachexia. Since cachexia is also associated with increased hospitalizations, this outcome may also show improvement with NSAID exposure. ^ Design. In this retrospective study, computerized records from 700 non-small cell lung cancer patients (NSCLC) were reviewed, and 487 (69.57%) were included in the final analyses. Exclusion criteria were severe chronic obstructive pulmonary disease, significant peripheral edema, class III or IV congestive heart failure, liver failure, other reasons for weight loss, or use of research or anabolic medications. Information on medication history, body weight and hospitalizations was collected from one year pre-diagnosis until three years post-diagnosis. Exposure to NSAIDs was defined if a patient had a history of being treated with NSAIDs for at least 50% of any given year in the observation period. We used t-test and chi-square tests for statistical analyses. ^ Results. Neither the proportion of patients with cachexia (p=0.27) nor the number of hospitalizations (p=0.74) differed among those with a history of NSAID use (n=92) and those without (n=395). ^ Conclusions. In this study, NSAID exposure was not significantly associated with weight loss or hospital admissions in patients with NSCLC. Further studies may be needed to confirm these observations.^

Maternal exposure to hazardous air pollutants and oral clefts among offspring: Texas, 1999-2008

Birth defects are a leading cause of infant mortality in the United States. About one in 33 births in the United States is diagnosed with birth defects. Common birth defects include neural tube defects, Down syndrome and oral clefts. The present study focused on oral clefts. ^ Oral clefts refer to the malformation of lip, mouth or both. Birth prevalence of oral clefts in Texas is about 11 per 10,000 births. Etiologically, oral clefts have been classified into two groups, cleft lip with or without cleft palate (CL±P) and isolated cleft palate (CP). In spite of their high prevalence and clinical significance, the etiology of oral clefts in humans has not been well understood. Though a number of risk factors have been identified in epidemiological studies, most of them do not explain the majority of the cases. The need to identify novel risk factors associated with oral clefts provided the motivation for this study. The present study focused on maternal exposure to several hazardous air pollutants. A common subgroup of hazardous air pollutants is the volatile organic compounds found in petroleum derivatives. Four important hydrocarbons in this group are benzene, toluene, ethyl benzene and xylenes (BTEX). ^ The specific aim of this study was to evaluate the association between maternal exposure to environmental levels of BTEX and oral clefts among offspring in Texas for the period 1999-2008. ^ A case-control study design was used to assess if maternal exposure to BTEX increased the risk of oral clefts. The Texas Birth Defects Registry provided data on cases of non-syndromic oral clefts delivered in Texas during the period 1999-2008. Census tract level maternal exposure to BTEX concentrations were obtained from the Hazardous Air Pollutant Exposure Model (HAPEM) developed by the U.S. Environmental Protection Agency. Unconditional logistic regression was used to assess the relationship between maternal exposure to BTEX levels and risk of oral clefts in offspring. ^ In the selected population, mothers who had high estimated exposure to any of the BTEX compounds were not more likely to deliver an offspring with oral clefts. Future research efforts will focus on additional birth defects and thorough assessment of additional potential confounders.^

Multiple stressor effects of near-future elevated seawater temperature and decreased pH on righting and escape behaviors of two common Antarctic gastropods

Warming seawater temperatures and ocean acidification on the coastal western Antarctic Peninsula pose unique challenges to stenothermal marine invertebrates. The present study examines prospective sub-lethal effects of elevated temperature, pCO2, and resultant decrease in seawater pH, on righting behavior and maximal escape speeds for two common gastropods, the limpet Nacella concinna (Strebel) and mesogastropod snail Margarella antarctica (Lamy). Replicate individuals held in individual containers were exposed to four combinations of seawater temperature (1.5 °C-current average, 3.5 °C-projected average by 2100) and pH (pH 8.0-current average, pH 7.8-projected average by 2100 as a result of elevated pCO2 levels) for a period of 6 weeks. Following this chronic exposure, righting behavior, determined for the limpets as proportion to right over 24 h and for snails as time to right, as well as maximum escape speed following contact with a sea star predator were measured. We found no significant differences in proportions of limpets displaying the capacity to right among the four temperature-pH treatments. However, there was a significant temperature-pH interaction effect for mean righting times in snails, indicating that the effect of pH on the time to right is dependent on temperature. We found no significant effects of temperature or pH on mean maximal escape speed in limpets. Additionally, we observed a significant temperature-pH interaction effect for mean maximal escape speed in snails. These interactive effects make it difficult to make clear predictions about how these environmental factors may impact behavioral responses.

9-28 d of exposure to elevated pCO2 reduces avoidance of predator odour but had no effect on behavioural lateralization or swimming activity in a temperate wrasse(Ctenolabrus rupestris)

Most studies on the impact of near-future levels of carbon dioxide on fish behaviour report behavioural alterations, wherefore abnormal behaviour has been suggested to be a potential consequence of future ocean acidification and therefore a threat to ocean ecosystems. However, an increasing number of studies show tolerance of fish to increased levels of carbon dioxide. This variation among studies in susceptibility highlights the importance of continued investigation of the possible effects of elevated pCO2. Here, we investigated the impacts of increased levels of carbon dioxide on behaviour using the goldsinny wrasse (Ctenolabrus rupestris), which is a common species in European coastal waters and widely used as cleaner fish to control sea lice infestation in commercial fish farming in Europe. The wrasses were exposed to control water conditions (370 µatm) or elevated pCO2 (995 µatm) for 1 month, during which time behavioural trials were performed. We investigated the possible effects of CO2 on behavioural lateralization, swimming activity, and prey and predator olfactory preferences, all behaviours where disturbances have previously been reported in other fish species after exposure to elevated CO2. Interestingly, we failed to detect effects of carbon dioxide for most behaviours investigated, excluding predator olfactory cue avoidance, where control fish initially avoided predator cue while the high CO2 group was indifferent. The present study therefore shows behavioural tolerance to increased levels of carbon dioxide in the goldsinny wrasse. We also highlight that individual fish can show disturbance in specific behaviours while being apparently unaffected by elevated pCO2 in other behavioural tests. However, using experiments with exposure times measured in weeks to predict possible effects of long-term drivers, such as ocean acidification, has limitations, and the behavioural effects from elevated pCO2 in this experiment cannot be viewed as proof that these fish would show the same reaction after decades of evolution.

Developmental exposure to vasopressin increases aggression in adult prairie voles

Although the biological roots of aggression have been the source of intense debate, the precise physiological mechanisms responsible for aggression remain poorly understood. In most species, aggression is more common in males than females; thus, gonadal hormones have been a focal point for research in this field. Although gonadal hormones have been shown to influence the expression of aggression, in many cases aggression can continue after castration, indicating that testicular steroids are not completely essential for the expression of aggression. Recently, the mammalian neuropeptide arginine vasopressin (AVP) has been implicated in aggression. AVP plays a particularly important role in social behavior in monogamous mammals, such as prairie voles (Microtus ochrogaster). In turn, the effects of social experiences may be mediated by neuropeptides, including AVP. For example, sexually naïve prairie voles are rarely aggressive. However, 24 h after the onset of mating, males of this species become significantly aggressive toward strangers. Likewise, in adult male prairie voles, central (intracerebroventricular) injections of AVP can significantly increase intermale aggression, suggesting a role for AVP in the expression of postcopulatory aggression in adult male prairie voles. In this paper, we demonstrate that early postnatal exposure to AVP can have long-lasting effects on the tendency to show aggression, producing levels of aggression in sexually naïve, adult male prairie voles that are comparable to those levels observed after mating. Females showed less aggression and were less responsive to exogenous AVP, but the capacity of an AVP V1a receptor antagonist to block female aggression also implicates AVP in the development of female aggression.

A common polymorphism associated with antibiotic-induced cardiac arrhythmia

Drug-induced long QT syndrome (LQTS) is a prevalent disorder of uncertain etiology that predisposes to sudden death. KCNE2 encodes MinK-related peptide 1 (MiRP1), a subunit of the cardiac potassium channel IKr that has been associated previously with inherited LQTS. Here, we examine KCNE2 in 98 patients with drug-induced LQTS, identifying three individuals with sporadic mutations and a patient with sulfamethoxazole-associated LQTS who carried a single-nucleotide polymorphism (SNP) found in ≈1.6% of the general population. While mutant channels showed diminished potassium flux at baseline and wild-type drug sensitivity, channels with the SNP were normal at baseline but inhibited by sulfamethoxazole at therapeutic levels that did not affect wild-type channels. We conclude that allelic variants of MiRP1 contribute to a significant fraction of cases of drug-induced LQTS through multiple mechanisms and that common sequence variations that increase the risk of life-threatening drug reactions can be clinically silent before drug exposure.

Conserved promoter elements in the CYP6B gene family suggest common ancestry for cytochrome P450 monooxygenases mediating furanocoumarin detoxification.

Despite the fact that Papilio glaucus and Papilio polyxenes share no single hostplant species, both species feed to varying extents on hostplants that contain furanocoumarins. P. glaucus contains two nearly identical genes, CYP6B4v2 and CYP6B5v1, and P. polyxenes contains two related genes, CYP6B1v3 and CYP6B3v2. Except for CYP6B3v2, the substrate specificity of which has not yet been defined, each of the encoded cytochrome P450 monooxygenases (P450s) metabolizes an array of linear furanocoumarins. All four genes are transcriptionally induced in larvae by exposure to the furanocoumarin xanthotoxin; several are also induced by other furanocoumarins. Comparisons of the organizational structures of these genes indicate that all have the same intron/exon arrangement. Sequences in the promoter regions of the P. glaucus CYP6B4v2/CYP6B5v1 genes and the P. polyxenes CYP6B3v2 gene are similar but not identical to the -146 to -97 region of CYP6B1v3 gene, which contains a xanthotoxin-responsive element (XRE-xan) important for basal and xanthotoxin-inducible transcription of CYP6B1v3. Complements of the xenobiotic-responsive element (XRE-AhR) in the dioxin-inducible human and rat CYP1A1 genes also exist in all four promoters, suggesting that these genes may be regulated by dioxin. Antioxidant-responsive elements (AREs) in mouse and rat glutathione S-transferase genes and the Barbie box element (Bar) in the bacterial CYP102 gene exist in the CYP6B1v3, CYP6B4v2, and CYP6B5v1 promoters. Similarities in the protein sequences, intron positions, and xanthotoxin- and xenobiotic-responsive promoter elements indicate that these insect CYP6B genes are derived from a common ancestral gene. Evolutionary comparisons between these P450 genes are the first available for a group of insect genes transcriptionally regulated by hostplant allelochemicals and provide insights into the process by which insects evolve specialized feeding habits.

An investigation into the similarities and differences governing the cryopreservation success of koala (Phascolarctos cinereus: goldfuss) and common wombat (Vombatus ursinus: shaw) spermatozoa

The aim of this study was to determine the relative cryopreservation success of koala and wombat spermatozoa and to investigate reasons for their respective post-thaw survival by examining the sperm's response to a range of osmotic media and determining the presence and distribution of F-actin. An hypothesis was proposed that F-actin may be imparting a degree of structural inflexibility to the koala sperm plasma membrane; hence, exposure of spermatozoa to cytochalasin D (5 mu M), a F-actin depolymerisation agent, should result in increased plasticisation of the membrane and greater tolerance of cell volume changes that typically occur during cryopreservation. In experiment 1, koala (n = 4) and wombat (n = 4) spermatozoa packaged in 0.25 mL straws were cryopreserved using two freezing rates (fast-3 cm above liquid N2 interface; slow-6 degrees C/min in a freezing chamber) and two glycerol concentrations (8 and 14% v/v) in a tris-citrate glucose buffer with 15% (v/v) egg yolk. Wombat spermatozoa showed better (P < 0.01) post-thaw survival (% motile, % intact plasma membranes, % decondensed sperm heads) than koala spermatozoa. When exposed to media of varying osmolality, koala spermatozoa were less tolerant (% intact plasma membrane) of hyper-osmotic conditions (920 and 1410mOsmol/kg) than wombat spermatozoa. F-actin was localised using a monoclonal antibody but only found in the wombat sperm head. When koala and wombat spermatozoa were exposed to media of varying osmolality, cytochalasin D had no beneficial effect on sperm survival (% intact plasma membranes). This study has demonstrated that wombat spermatozoa are highly tolerant of cryopreservation when compared to koala sperm but that spermatozoa from both species show greatest post-thaw survival when frozen slowly in 14% glycerol. Koala sperm are also particularly susceptible to hyper-osmotic environments but lack of detectable F-actin in the koala spermatozoan suggests that poor cryopreservation success in this species is unlikely to be associated with F-actin induced plasma membrane inflexibility. (c) 2006 Elsevier Inc. All rights reserved.