Care of transgender patients by diagnostic radiographers: What can be learnt from the literature

INTRODUCTION

Transgender patients have described negative healthcare experiences, including discrimination and feeling unwelcome. Additionally, these patients are at risk of inadequate or unsafe care due to healthcare providers being unable to obtain and record transgender patients' correct gender and assigned birth sex. This literature review aims to review radiology and radiographer articles published since 2018 about transgender healthcare issues and make recommendations that can be applied by diagnostic radiographers, their managers and diagnostic radiography programme providers.

METHOD

A literature search used multiple databases containing peer-reviewed articles. Boolean operators and key words were utilised. Identified articles were searched to identify any articles not found by searching the databases. Themes and sub-themes from each paper were identified and discussed.

RESULTS

Three key themes were identified: education, systems and environment. Education sub-themes were knowledge and awareness. Systems sub-themes were recording gender correctly and discriminating/stigmatising policies. Environment sub-themes were transgender-friendly symbols and environmental dysphoria.

CONCLUSION

Transgender patients still face barriers to equitable care. Several recommendations were made based on the thematic discussion that could be applied by diagnostic radiographers, student radiographers, radiology managers, University training providers, and professional body organisations. Diagnostic radiography programmes should include training on both clinical topics and cultural competence. Radiology managers should display transgender-positive symbols in their departments and ensure their policies are non-discriminatory and non-stigmatising. Radiology hardware and software providers should provide the ability to record non-binary genders and birth-assigned sex.

IMPLICATIONS FOR PRACTICE

Transgender patients have the right to receive equitable care from diagnostic radiographers during their imaging examination and radiology attendance, and that any risks relating to their transgender status should be correctly managed with appropriate sensitivity.

Polycomb contraction differentially regulates terminal human hematopoietic differentiation programs

Background

Lifelong production of the many types of mature blood cells from less differentiated progenitors is a hierarchically ordered process that spans multiple cell divisions. The nature and timing of the molecular events required to integrate the environmental signals, transcription factor activity, epigenetic modifications, and changes in gene expression involved are thus complex and still poorly understood. To address this gap, we generated comprehensive reference epigenomes of 8 phenotypically defined subsets of normal human cord blood.

Results

We describe a striking contraction of H3K27me3 density in differentiated myelo-erythroid cells that resembles a punctate pattern previously ascribed to pluripotent embryonic stem cells. Phenotypically distinct progenitor cell types display a nearly identical repressive H3K27me3 signature characterized by large organized chromatin K27-modification domains that are retained by mature lymphoid cells but lost in terminally differentiated monocytes and erythroblasts. We demonstrate that inhibition of polycomb group members predicted to control large organized chromatin K27-modification domains influences lymphoid and myeloid fate decisions of primary neonatal hematopoietic progenitors in vitro. We further show that a majority of active enhancers appear in early progenitors, a subset of which are DNA hypermethylated and become hypomethylated and induced during terminal differentiation.

Conclusion

Primitive human hematopoietic cells display a unique repressive H3K27me3 signature that is retained by mature lymphoid cells but is lost in monocytes and erythroblasts. Intervention data implicate that control of this chromatin state change is a requisite part of the process whereby normal human hematopoietic progenitor cells make lymphoid and myeloid fate decisions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01315-1.

P214 Clinical audit of in-patient echocardiography in acute heart failure: real world data from a tertiary hospital

Background

Over the last ten years, an increase in admission rates for acute heart failure (HF) has been noted in England and Wales, with one year mortality rates varying between 30% and 60%. Transthoracic echocardiography (TTE) is recommended within 48 hours of admission for suspected acute heart failure, so to guide treatment accordingly.

Our centre has a specialist team who assesses patients with suspected HF on admission, and refers them for urgent in-patient TTE, using two priority in-patient echo slots per day. Patients are initially referred for HF assessment by general medics and geriatricians, across non-specialist medical wards. We audited the referrals and results of those who received TTE in this context.

Methods and results

We screened the medical notes of 252 patients admitted with suspected HF between January and December 2017, and reviewed the echocardiography results of those who received it during their admission.

50% of these patients were female and 59% were elderly (over 80 years old). 245 of these patients (97.2%) had in-patient echocardiography performed during their hospital stay. The mean wait for echocardiography was 0.58 days, with 92% of the scans being performed within 24 hours. The mean admission duration was 8.6 days (SD 10.9). 17.9% of patients were readmitted with suspected heart failure within six months, 69% of which were elderly.

The majority of this cohort presented with heart failure with preserved ejection fraction (HFpEF), 50%), followed by heart failure with reduced ejection fraction (HFrEF, 29%) and heart failure with mid-range ejection fraction (HFmrEF, 16%). 41% of the patients who received an echocardiogram were in atrial fibrillation, 51% of which were diagnosed with HFpEF.

All patients had their HF medical treatment optimised post-echocardiography and only 18.4% were readmitted within 6 months of the first admission. The majority of these patients was elderly (68.9%). 38.8% of patients who received echocardiography were referred for specialist clinic follow-up, with HFrEF patients more likely to be seen in this setting (42%).

Six-month mortality occurred in 19.8% of patients; cause of death (COD) was undocumented in 25.8% of cases. In those where a post-mortem was conducted, the main COD was HF (16.7%), followed by sepsis (13.6%), cardiac (6.1%) and respiratory arrest (6.1%). 66% of the deceased patients were elderly and 48% presented with HFpEF.

Conclusion

Our cohort is an accurate representation of the current HF statistics seen nationwide. Appropriate treatment was offered to the large majority of patients who received in-patient echocardiography within the first 24 hours of their admission, with low six-month readmission rates. This approach also allowed for the inclusion of these patients on a systematic review plan, including specialist cardiology follow-up. Our numbers are consistent with the higher awareness about HFpEF currently seen in the medical community.

P796 Feasibility of exercise stress echocardiography and its correlation with angiographically significant coronary disease

Background

European Society of Cardiology (ESC) guidelines on the management of stable coronary artery disease (CAD) advocate stress echocardiography (SE) as a first line assessment for functionally significant ischaemia. Pharmacological stressors such as dobutamine are typically utilised in most UK centres in view of practical benefits when compared with treadmill testing. However, exercise provides the best physiological mimic and enables additional data on haemodynamics and electrocardiogram (ECG) changes to be obtained.

Purpose

To assess the feasibility and safety of exercise stress echocardiography (ESE), and the correlation of positive testing with significant coronary disease and major adverse cardiovascular events.

Methods

A retrospective, single-centre analysis of 500 consecutive patients undergoing ESE for investigation of stable CAD. Cases were excluded when a pharmacological stressor was utilised, or in contexts where ESE was performed for other clinical indications. ESE reports were interrogated for patient demographics, co-morbidities, achievement of target heart rate (HR), procedural sequelae, image quality and findings. Electronic records were reviewed after 24 months to assess results of invasive angiography, when performed, and long-term outcomes including myocardial infarction (MI) and cardiovascular mortality. Concordance between ischaemic territory on ESE and coronary lesions on angiography was also collated.

Results

95% (475/500) of patients were suitable for inclusion. Of these, 83% (394/475) achieved target HR. Sequelae arose in 0.02% (9/475), with the most frequent being ectopy (4 cases). Image quality was adequate in 98% (465/475), with the requirement for contrast agent in the remainder. There were no significant differences in burden of cardiovascular risk factors between the positive and negative ESE groups. 13% (63/475) were positive for inducible ischaemia in one or more myocardial segments. Of these, 71% (45/65) underwent angiography, with 48% (31/65) requiring stenting or bypass surgery. Ischaemic territory on ESE correlated with angiographic lesions in 65% (29/45) of cases. ESE underestimated extent of significant CAD in only 7% (3/45). In the subcohort positive for ESE, 3% (2/63) suffered a MI and cardiovascular mortality was 1.5% (1/63).

Conclusions

ESE is a safe, non-invasive modality for functional testing that reaches diagnostic threshold in the vast majority of cases. It has reasonable concordance in localising ischaemic coronary territory to enable targeted revascularisation.

Zebrafish sp7 mutants show tooth cycling independent of attachment, eruption and poor differentiation of teeth

The capacity to fully replace teeth continuously makes zebrafish an attractive model to explore regeneration and tooth development. The requirement of attachment bone for the appearance of replacement teeth has been hypothesized but not yet investigated. The transcription factor sp7 (osterix) is known in mammals to play an important role during odontoblast differentiation and root formation. Here we study tooth replacement in the absence of attachment bone using sp7 zebrafish mutants. We analysed the pattern of tooth replacement at different stages of development and demonstrated that in zebrafish lacking sp7, attachment bone is never present, independent of the stage of tooth development or fish age, yet replacement is not interrupted. Without bone of attachment we observed abnormal orientation of teeth, and abnormal connection of pulp cavities of predecessor and replacement teeth. Mutants lacking sp7 show arrested dentinogenesis, with non-polarization of odontoblasts and only a thin layer of dentin deposited. Osteoclast activity was observed in sp7 mutants; due to the lack of bone of attachment, remodelling was diminished but nevertheless present along the pharyngeal bone. We conclude that tooth replacement is ongoing in the sp7 mutant despite poor differentiation and defective attachment. Without bone of attachment tooth orientation and pulp organization are compromised.

Catalytic formation of C(sp3)–F bonds via decarboxylative fluorination with mechanochemically-prepared Ag2O/TiO2 heterogeneous catalysts

Mechanochemically-prepared, Ag₂O-containing solid materials, are shown to be efficient heterogeneous catalysts for the synthesis of C(sp³)–F bonds via decarboxylative fluorination.

Current assays overestimate 25-hydroxyvitamin D3 and underestimate 25-hydroxyvitamin D2 compared with HPLC: need for assay-specific decision limits and metabolite-specific assays

Background: Clinical demand for quick, cheap, precise and accurate 25-hydroxyvitamin D (25(OH)D) results has led to the development of a variety of assay methods. Lack of standardization of these methods has resulted in intermethod disagreement and challenged whether current assays recognize 25(OH)D2 and 25(OH)D3 equally.

Methods: We studied 172 patient samples from hip fracture cases using DiaSorin (DS) and IDS radioimmunoassays and the Nichols Advantage-automated protein binding assay (NA-CLPBA) in comparison to high-performance liquid chromatography (HPLC). 52 patient samples were analysed before and after three months treatment with 1000 IU of daily ergocalciferol (vitamin D2).

Results: Linear regression analysis in pre-treatment samples demonstrated a positive Y-intercept for each immunoassay compared with HPLC, and a slope that varied from 0.64 (IDS) to 0.97 (DS, NA-CLPBA). Bland Altman analysis demonstrated that all the three assays had a proportional positive bias relative to HPLC at values from 20 to 50 nmol/L. Regression analysis of post-treatment samples demonstrated a slope that was not significantly different from zero for the IDS and NA-CLPBA and 0.2 for the DS method, with a positive intercept for all assays of between 8 and 22, indicating less than 50% of 25(OH)D2 measured by HPLC was detected.

Conclusions: These results demonstrate the need for assay-specific decision limits for 25(OH)D3 in order to define appropriate thresholds for treatment institution. Treatment with vitamin D2 may not be accurately monitored with any of the three commercial assays studied. Clinicians and biochemists who continue to use 25(OH)D assays need to be urgently informed of these issues.

A multidisciplinary guided practical on type I diabetes engaging students in inquiry-based learning

In the present article, we describe a 3-day experimental workshop on type I diabetes aimed at helping high school students to understand how fundamental research on glycemia regulation contributes to the development of scientific knowledge and therapeutic strategies. The workshop engaged students in open-ended investigations and guided experiments. Each class was divided into three or four groups, with each group working with a trained doctoral student or postdoctoral fellow. During an initial questioning phase, students observed slides depicting the glycemia of individuals in various situations. Students identified hyperglycemic individuals relative to the average glycemia of the displayed population. Students were asked to devise a treatment for these diabetics. They quickly realized that they couldn't experiment on patients and understood the need for laboratory models. Each group gave ideas of experiments to perform. We then explained, taking into account their propositions, the protocols students could execute to address one of the following questions: Which criteria must an animal model of diabetes fulfill? How do pancreatic cells maintain glycemia? Is there a way to produce an insulin protein similar to the one released by human pancreatic cells? We used two different evaluation metrics of the workshop: a questionnaire filled out by the students before and after the workshop and a poster produced by students at the end of the workshop. We found that this educational approach successfully improved student awareness and understanding of the scientific reasoning and research process.

Hands-on experiments on glycemia regulation and type 1 diabetes

In the present article, we describe a 3-day experimental workshop on glycemia regulation and type 1 diabetes that engages students in open-ended investigations and guided experiments leading to results that are not already known to them. After an initial questioning phase during which students observe PowerPoint slides depicting the glycemia (blood glucose levels) of individuals in various situations, students design, execute, and interpret experiments to address one of the following questions: 1) Which criteria must an animal model of diabetes fulfill? 2) How do pancreatic cells maintain glycemia constant? and 3) Is there a way to produce an insulin protein similar to the one released by human pancreatic cells? Students then 1) measure glycemia and glycosuria in control mice and in a mouse model of type 1 diabetes (Alloxan-treated mice), 2) measure the release of insulin by pancreatic β-cells (INS-1 cell line) in response to different concentrations of glucose in the extracellular medium, and 3) transfect Chinese hamster ovary cells with a plasmid coding for green fluorescent protein, observe green fluorescent protein fluorescence of some of the transfected Chinese hamster ovary cells under the microscope, and observe the characteristics of human insulin protein and its three-dimensional conformation using RASMOL software. At the end of the experimental session, students make posters and present their work to researchers. Back at school, they may also present their work to their colleagues.

Lymphangiogenesis in abdominal aortic aneurysm

Background

Ongoing angiogenesis is implicated in the inflammatory environment that characterizes abdominal aortic aneurysm (AAA). Although lymphangiogenesis has been associated with chronic inflammatory conditions, it has yet to be demonstrated in AAA. The aim was to determine the presence of lymphangiogenesis and to delineate the relationship between inflammation and neovascularization in AAA tissue.

Methods

AAA samples and preoperative computed tomography images were obtained from patients undergoing elective AAA repair. Control samples were age-matched abdominal aortic tissue. Specific immunostains for blood vessels (CD31, CD105), lymphatic vessels (D2-40), vascular endothelial growth factor (VEGF) A and VEGF receptor (VEGFR) 3 allowed characterization and quantitation of vasculature.

Results

The AAA wall contained high levels of inflammatory infiltrate; microvascular densities of blood (P < 0·001) and lymphatic (P = 0·003) vessels were significantly increased in AAA samples compared with controls. Maximal AAA vascularity was observed in inflammatory areas, with vessels that stained positively for CD31 (ρ = 0·625, P = 0·017), CD105 (ρ = 0·692, P = 0·009) and D2-40 (ρ = 0·675, P = 0·008) correlating positively with the extent of inflammation. Increased VEGFR-3 and VEGF-A expression was also evident within inflammatory AAA areas.

Conclusion

These findings demonstrated lymphatic vessel involvement in end-stage AAA disease, which was associated with the degree of inflammation, and confirmed the involvement of neovascularization.

Timing of developmental sequences in different brain structures: physiological and pathological implications

The developing brain is not a small adult brain. Voltage- and transmitter-gated currents, like network-driven patterns, follow a developmental sequence. Studies initially performed in cortical structures and subsequently in subcortical structures have unravelled a developmental sequence of events in which intrinsic voltage-gated calcium currents are followed by nonsynaptic calcium plateaux and synapse-driven giant depolarising potentials, orchestrated by depolarizing actions of GABA and long-lasting NMDA receptor-mediated currents. The function of these early patterns is to enable heterogeneous neurons to fire and wire together rather than to code specific modalities. However, at some stage, behaviourally relevant activities must replace these immature patterns, implying the presence of programmed stop signals. Here, we show that the developing striatum follows a developmental sequence in which immature patterns are silenced precisely when the pup starts locomotion. This is mediated by a loss of the long-lasting NMDA-NR2C/D receptor-mediated current and the expression of a voltage-gated K(+) current. At the same time, the descending inputs to the spinal cord become fully functional, accompanying a GABA/glycine polarity shift and ending the expression of developmental patterns. Therefore, although the timetable of development differs in different brain structures, the g sequence is quite similar, relying first on nonsynaptic events and then on synaptic oscillations that entrain large neuronal populations. In keeping with the 'neuroarcheology' theory, genetic mutations or environmental insults that perturb these developmental sequences constitute early signatures of developmental disorders. Birth dating developmental disorders thus provides important indicators of the event that triggers the pathological cascade leading ultimately to disease.

Negative pressure wound therapy as an adjunct to compression for healing chronic venous ulcers

OBJECTIVE

To determine the efficacy of negative pressure wound therapy (NPWT), when used in combination with compression bandaging, for healing chronic resistant venous ulcers.

METHOD

In this pilot study, seven patients (with a total of 12 chronic resistant venous ulcers) received adjunctive NPWT and compression bandaging for 4 weeks. Their wounds were monitored for a total of 12 weeks.

RESULTS

Dormant ulcers were seen to rapidly develop into healthy wounds, with a granulating base.

CONCLUSION

This regimen may have a role in stimulating chronic venous ulcers into healing wounds, or in preparing them for skin grafting.

Socio demographic correlates of pregnancy in cancer survivors using data from NHANES 1999–2002

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Background: Many cancer therapies can cause infertility and impaired fecundity. These are important long term outcomes of concern for survivors, which can affect their quality of life. Little is known about the socio-demographic correlates of impaired fecundity (inability to get pregnant or carry child to term) in cancer survivors. The purpose of this study is to assess socio demographic correlates of “ever pregnant” in the general American population of cancer survivors. Methods: Using data from adult (>20 years old) female cancer survivor participants of the 1999–2002 iterations of the population based cross sectional survey, National Health and Nutrition Examination Study (NHANES), we used logistic regression to examine the relationship between “ever” being pregnant and socio-demographic variables. Results: Complete data were available for 7558 females. Cancer survivors represented 8.2 % of that population. On univariate analysis, being married and having ≤ high school education were associated with a greater likelihood of “ever” pregnant compared to those unmarried and those with greater than high school education (p < .05). In cancer survivors of reproductive age (between the ages of 20 and 50) being Black or Hispanic was associated with a greater likelihood of “ever” pregnant compared to whites (p < .05). Interestingly, differences in race, income, health insurance status, and marital status were not significantly associated with “ever” pregnant on multivariate analysis of all female survivors older than 20. Conclusions: These results suggest there are differences in impaired fecundity between different groups of cancer survivors. However, questions in NHANES were not designed to explicitly examine fertility related outcomes. Additional studies that specifically examine measures of fertility in survivors are needed to understand the burden of this undesirable outcome in survivors.

No significant financial relationships to disclose.

Preservation of the direct and indirect pathways in an in vitro preparation of the mouse basal ganglia

We have developed a slice preparation of the mouse basal ganglia which contains portions of the striatum, external pallidum, subthalamic nucleus and substantia nigra and the neocortex. This basal ganglia slice is unique in preserving functional direct and indirect connections between the striatum and the substantia nigra as well as interconnectivity between the globus pallidus and the subthalamic nucleus. We used fiber tract tracing studies and electrophysiological recordings to demonstrate the full functionality of these pathways. Deposits of 1,1'-dioctadecyl-3,3,3',3'-tetra-methylindocarbocyamine perchlorate in the different basal ganglia resulted in labeled fibers in each of their target nuclei. Confirming these results, electrical stimulation of the different nuclei elicited whole-cell recorded postsynaptic potentials in their target neurons with an appropriate pharmacological profile. Electrical and glutamate activation of the striatum evoked bursts of glutamatergic and GABAergic activities in whole-cell recorded nigral neurons indicating that the direct and indirect pathways are operative in this slice. It also showed that the responses evoked are not due to fibers en passant but to the activation of striatal cell bodies. These findings provide the first direct evidence for a preserved basal ganglia circuitry in vitro and make the basal ganglia slice a suitable preparation for analyzing the activity of the direct and indirect pathways in physiological and pathological conditions.

Immunomodulatory effects of Toll-like receptor-7 activation on chronic lymphocytic leukemia cells

Weak immunogenicity of chronic lymphocytic leukemia (CLL) cells may contribute to disease progression and inhibit effective immunotherapy. Accordingly, agents that enhance the immunogenicity of CLL cells may be useful in immunotherapeutic approaches to this disease. Since Toll-like receptors (TLRs) are major regulators of innate immunity and initiation of adaptive immunity, we studied the effects of viral pathogen associated molecular pattern agonists (that are recognized by TLRs) on the costimulatory phenotype and function of CLL cells. CLL cells (especially those with high endogenous expression of CD38) responded to TLR7-activating imidazoquinolines and guanosine analogs by increasing costimulatory molecule expression, producing inflammatory cytokines, and becoming more sensitive to killing by cytotoxic effectors. Additional activation of protein kinase C pathways increased the ability to stimulate T-cell proliferation, blocked phosphorylation of the transcription factor, signal transducer and activator of transcription (STAT)3, and resulted in the acquisition of a dendritic cell surface phenotype by TLR7-activated CLL cells. Normal B cells also responded to TLR7 activation by increasing costimulatory molecule expression and cytokine production. These findings suggest a potential role for TLR7 agonists in CLL immunotherapy.

Health related quality of life of patients with refractory angina before and one year after enrolment onto a refractory angina program

OBJECTIVE

This study was designed to assess the impact of a refractory angina programme on the health related quality of life for patients with chronic refractory angina (CRA) one year following enrolment.

DESIGN

A one year prospective audit.

SETTING

Specialist refractory angina clinic at a tertiary cardiac referral centre.

PATIENTS

69 consecutive refractory angina patients referred to a regional refractory angina centre from 1/03/2001 to 1/09/2002.

INTERVENTIONS

Pain treatment algorithm in accordance with the recommendations of the national refractory angina guideline committee.

MAIN OUTCOME MEASURES

Improvements in quality of life indices were assessed using Seattle angina questionnaire (SAQ), and short form-12 (SF-12) with changes in mood determined using the hospital anxiety and depression (HAD) questionnaire.

RESULTS

All dimensions of the SF-12 and SAQ were superior at one year with significant improvement seen with the mental component of SF-12 (p = 0.023), and four of the five SAQ domains, angina stability (p = 0.028), angina frequency (p=0.02), treatment satisfaction (p=0.001) and quality of life (p < 0.001). All the significant changes within the SAQ domains were large enough to be considered clinically relevant. At one year the anxiety and depression domains were significantly improved from baseline (p = 0.015, 0.018) with clinical anxiety levels falling significantly from 55% to 40%, a relative reduction of 28% (p = 0.008).

CONCLUSIONS

Implementation of the national refractory angina guidelines in a prospective study of 69 consecutive CRA patients significantly improved health related quality of life status at one year.

High-frequency stimulation produces a transient blockade of voltage-gated currents in subthalamic neurons

The effect of high-frequency stimulation (HFS) of the subthalamic nucleus (STN) was analyzed with patch-clamp techniques (whole cell configuration, current- and voltage-clamp modes) in rat STN slices in vitro. A brief tetanus, consisting of 100-micros bipolar stimuli at a frequency of 100--250 Hz during 1 min, produced a full blockade of ongoing STN activity whether it was in the tonic or bursting mode. This HFS-induced silence lasted around 6 min after the end of stimulation, was frequency dependent, could be repeated without alteration, and was not synaptically induced as it was still observed in the presence of blockers of ionotropic GABA and glutamate receptors or in the presence of cobalt at a concentration (2 mM) that blocks voltage-gated Ca(2+) channels and synaptic transmission. During HFS-induced silence, the following alterations were observed: the persistent Na(+) current (I(NaP)) was totally blocked (by 99%), the Ca(2+)-mediated responses were strongly reduced including the posthyperpolarization rebound (-62% in amplitude) and the plateau potential (-76% in duration), suggesting that T- and L-type Ca(2+) currents are transiently depressed by HFS, whereas the Cs(+)-sensitive, hyperpolarization-activated cationic current (I(h)) was little affected. Thus a high-frequency tetanus produces a blockade of the spontaneous activities of STN neurons as a result of a strong depression of intrinsic voltage-gated currents underlying single-spike and bursting modes of discharge. These effects of HFS, which are completely independent of synaptic transmission, provide a mechanism for interrupting ongoing activities of STN neurons.

Growth hormone secretagogues and hypothalamic networks

Growth hormone secretagogues (GHSs) act at distinct levels to control growth hormone (GH) secretion. At the pituitary level they reinforce or extend a tonic GH-releasing-hormone (GHRH)-induced activated state by mobilizing intracellular Ca2+ store. At the hypothalamic level GHS actions are more complex than originally anticipated. Chronic treatments with GHS result in loss of responsiveness to the secretagogues, an effect probably accounted for by indirect negative feedback of GHS stimulated plasma GH levels over GHRH release. Moreover, intracerebroventricular treatments with GHS can have paradoxical, inhibitory effects on GH secretion. Several mechanisms can account for such dual effects. GHS receptors were found to extend far beyond the arcuate nucleus and are mainly coexpressed by GHRH, somatostatin, and neuropeptide Y (NPY) neurons. Activation of GHRH neurons by GHS can be direct or indirect. Indeed using antisense strategy we found that sstl are physiological activators of arcuate GHRH neurons and we propose that activation of SRIH arcuate interneurons by GHS can increase GHRH neuron activity. Moreover, GHS can stimulate distinct populations of NPY neurons having opposite effects on GH secretion: arcuate NPY interneurons, act as indirect facilitators of GHRH release, whereas, on the contrary, a different subset of NPY neurons projecting to the periventricular hypothalamus (those also involved in mediating leptin effects on GH) seems able to activate SRIH release.

Applications of low-cost, dual-fraction dust samplers

Porous polyurethane foams provide a low-cost method for separating dust into health-related fractions in accordance with recognized sampling conventions. A number of dust sampling instruments that make use of foam selectors have been described in recent literature, but practical experiences of using these instruments in real workplaces have not been widely reported. An IOM inhalable dust sampler incorporating a respirable-fraction selector foam was evaluated in a range of industries, for general occupational dust monitoring. The key issues addressed were those that determine the practicability of the instrument, such as limitations on particulate loading, losses or movements of particles during transportation of samples, and equivalence with conventional respirable dust sampling methods. The new sampler was found to be satisfactory in all these respects. The minor problems experienced have been addressed during the design of the production version of the foam cassette, which is available as an accessory for the existing IOM inhalable dust sampler. The key advantage of the new dust sampler is that it measures both inhalable and respirable dust concentrations in a single sample (hence the name: dual-fraction dust sampler). Therefore, it saves both time and money in industries where both inhalable and respirable dust are routinely monitored.

Slowly inactivating sodium current (I(NaP)) underlies single-spike activity in rat subthalamic neurons

One-half of the subthalamic nucleus (STN) neurons switch from single-spike activity to burst-firing mode according to membrane potential. In an earlier study, the ionic mechanisms of the bursting mode were studied but the ionic currents underlying single-spike activity were not determined. The single-spike mode of activity of STN neurons recorded from acute slices in the current clamp mode is TTX-sensitive but is not abolished by antagonists of ionotropic glutamatergic and GABAergic receptors, blockers of calcium currents (2 mM cobalt or 40 microM nickel), or intracellular Ca(2+) ions chelators. Tonic activity is characterized by a pacemaker depolarization that spontaneously brings the membrane from the peak of the afterspike hyperpolarization (AHP) to firing threshold (from -57.1 +/- 0.5 mV to -42.2 +/- 0.3 mV). Voltage-clamp recordings suggest that the Ni(2+)-sensitive, T-type Ca(2+) current does not play a significant role in single-spike activity because it is totally inactivated at potentials more depolarized than -60 mV. In contrast, the TTX-sensitive, I(NaP) that activated at -54.4 +/- 0.6 mV fulfills the conditions for underlying pacemaker depolarization because it is activated below spike threshold and is not fully inactivated in the pacemaker range. In some cases, the depolarization required to reach the threshold for I(NaP) activation is mediated by hyperpolarization-activated cation current (I(h)). This was directly confirmed by the cesium-induced shift from single-spike to burst-firing mode which was observed in some STN neurons. Therefore, a fraction of I(h) which is tonically activated at rest, exerts a depolarizing influence and enables membrane potential to reach the threshold for I(NaP) activation, thus favoring the single-spike mode. The combined action of I(NaP) and I(h) is responsible for the dual mode of discharge of STN neurons.

Patch-clamp-induced perturbations of [Ca(2+)](i) activity in somatotropes

Somatotropes and GC cells, a GH-producing cell line, exhibit [Ca(2+)](i) oscillations that result from rhythmic Ca(2+) action potentials. Determination of this operating mode required simultaneous recording of both parameters by fura-2 imaging and patch-clamp techniques. In order to test whether patch recording induces artificial alteration of the [Ca(2+)](i) oscillatory pattern, we recorded separately or simultaneously [Ca(2+)](i) and membrane potential. In the absence of any other stimulation, seal formation in patch-clamp recording evoked by itself a 2.5- to 4-fold persistent increase in basal [Ca(2+)](i), speeded up their frequency (from 0.03-0.17 to 0.4 Hz) and changed their pattern to a tonic mode. Patch-induced [Ca(2+)](i) increase was reproduced by mechanical contact between the pipette and the membrane. It was reduced by nifedipine, a blocker of L-type Ca(2+) channels, as well as by removal of external Na(+). It was fully blocked by external Ca(2+) removal or gadolinium. All patch-clamp-induced perturbations were reversed by membrane hyperpolarization. We propose that patch-clamp recording evokes Ca(2+) entry through L-type Ca(2+) channels either directly, or indirectly via membrane depolarization. This shows that patch recordings in endocrine cells showing mechanosensitivity have to be interpreted with caution, and explains why long-lasting patch recordings are so difficult to obtain.

Multiple genetic alterations, 4q28, a new suppressor region, and potential gender differences in human hepatocellular carcinoma

Primary hepatocellular carcinomas (HCCs) of different etiologies were studied to determine the rate of alteration of several genetic regions previously associated with the HCC phenotype. The focus of our study was to identify the frequency of genetic alterations within individual HCCs and their distribution among male and female cases. Genetic differences were evaluated between DNA isolated from tumor (T) and corresponding non-tumor (N) tissue using short tandem repeat (STR)-microsatellites and restriction fragment length polymorphism (RFLP) analyses. Twenty-eight HCC cases were studied with polymorphic markers from different parts of the genome. Three or more loci were identified with genetic alterations from 28 loci tested in 63% of HCC cases. The highest frequency of alteration occurred in the chromosome regions 1p36, 13q14, 17p13, and the 4q28 region identified in HCCs for the first time. High loss of heterozygosity (LOH) in 1p36, 4q28, 13q14, and 17p13 regions indicates important HCC suppressors within the regions. The study documents no association between cause and specific genetic change or their frequency in HCCs analyzed. The data document a significant gender distortion for genetic alteration in chromosome 13q14 and 17p13 regions and a concordant gender alteration rate in the 1p36 and 4q28 regions. An overall higher frequency of genetic alterations was identified in male cases. Future study with an extended number of HCC cases should substantiate the frequency of alteration between genders and identify tentative suppressors in the 1p36 and 4q28 regions.