Perceptions and attitudes toward COVID-19 vaccination among health professional students in Australia: a qualitative study

Using two qualitative data sources: free-text responses to an open-ended question of an online survey and subsequent interviews and focus groups, we explored perceptions and attitudes toward COVID-19 vaccination among health professional students enrolled in Australian universities during the pandemic with data collected from October 2021 to April 2022. Students provided free-text responses to the open-ended question (n = 313) in the online survey and participated in interviews or focus groups (n = 17). Data analysis revealed three themes, including perceptions of COVID-19 seriousness and the risk of contracting the virus, information dissemination, and attitudes toward the vaccine mandate. The study identified evolving perceptions of COVID-19 seriousness among Australian health professional students and their sentiments toward the vaccine mandate. There is a need to ensure the quality of information dissemination related to the vaccine mandate. This may not only support students' uptake of mandatory vaccination but also provide a means for them to address vaccination with healthcare consumers and patients.

Interventions to improve patient admission and discharge practices in adult intensive care units: A systematic review

OBJECTIVES

To identify and synthesise interventions and implementation strategies to optimise patient flow, addressing admission delays, discharge delays, and after-hours discharges in adult intensive care units.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. Five electronic databases, including CINAHL, PubMed, Emcare, Scopus, and the Cochrane Library, were searched from 2007 to 2023 to identify articles describing interventions to enhance patient flow practices in adult intensive care units. The Critical Appraisal Skills Program (CASP) tool assessed the methodological quality of the included studies. All data was synthesised using a narrative approach.

SETTING

Adult intensive care units.

RESULTS

Eight studies met the inclusion criteria, mainly comprising quality improvement projects (n = 3) or before-and-after studies (n = 4). Intervention types included changing workflow processes, introducing decision support tools, publishing quality indicator data, utilising outreach nursing services, and promoting multidisciplinary communication. Various implementation strategies were used, including one-on-one training, in-person knowledge transfer, digital communication, and digital data synthesis and display. Most studies (n = 6) reported a significant improvement in at least one intensive care process-related outcome, although fewer studies specifically reported improvements in admission delays (0/0), discharge delays (1/2), and after-hours discharge (2/4). Two out of six studies reported significant improvements in patient-related outcomes after implementing the intervention.

CONCLUSION

Organisational-level strategies, such as protocols and alert systems, were frequently employed to improve patient flow within ICUs, while healthcare professional-level strategies to enhance communication were less commonly used. While most studies improved ICU processes, only half succeeded in significantly reducing discharge delays and/or after-hours discharges, and only a third reported improved patient outcomes, highlighting the need for more effective interventions.

IMPLICATIONS FOR CLINICAL PRACTICE

The findings of this review can guide the development of evidence-based, targeted, and tailored interventions aimed at improving patient and organisational outcomes.

Facilitators and barriers to evidence-based practice in central venous access device insertion and management in an intensive care unit: A qualitative study

INTRODUCTION

Research evidence and clinical practice guidelines exist on preventing central line-associated bloodstream infections. However, there is limited knowledge about the barriers and facilitators to evidence-based central venous access device care.

AIM

The aim of this study was to investigate the facilitators and barriers to evidence-based central venous access device care in the adult intensive care setting.

METHOD

This exploratory qualitative study involved focus groups and interviews with registered nurses and physicians involved in central venous access device insertion and management in a tertiary Australian intensive care unit. Purposive sampling was used to recruit staff (n = 26) with varying years of clinical experience and clinical positions. Six focus groups and three individual interviews were conducted. Interviews were audio recorded, transcribed verbatim and analysed using content analysis.

RESULTS

Three overarching categories emerged: work structures to support optimal performance; processes to optimise quality of care, and factors influencing staff members' behaviour. Perceived facilitators to optimal central venous access device care included explicit language use in procedure documents, work-system integrated strategies, research evidence dissemination, audit, and feedback. However, there was a lack of consistency in practices such as audit, feedback, and patient participation.

CONCLUSION

To bring about effective improvement in central venous access device care, future interventions should be tailored to address identified barriers, including integrating audit and feedback into clinicians' work processes. Additionally, future research is needed to explore the role of patients and their families in central venous access device care.

IMPLICATIONS FOR CLINICAL PRACTICE

When developing practice policies or procedure manuals, it is important to use explicit language to ensure clear communication of evidence-based recommendations to clinicians. Strategies integrated into work processes can enhance adherence to evidence-based practice. Large departments with limited educators should explore innovative methods like online education to ensure optimal central venous access device care.

Barriers and facilitators to COVID-19 vaccine uptake among Australian health professional students during the pandemic: a nationwide study

Using a cross-sectional online survey we investigated knowledge, attitudes, and risk perception about COVID-19 vaccination and identified factors influencing vaccine uptake among Australian health professional students from October 2021 to January 2022. We analysed data from 1114 health professional students from 17 Australian universities. Most participants were enrolled in nursing programs (n = 958, 86.8%), and 91.6% (n = 858) of the participants received COVID-19 vaccination. Approximately 27% believed COVID-19 was no more serious than seasonal influenza and that they had a low risk of acquiring COVID-19. Nearly 20% disagreed that COVID-19 vaccines in Australia were safe and perceived they were at higher-risk of acquiring COVID infection than the general population. Higher-risk perception viewing vaccination as their professional responsibility, and vaccine mandate strongly predicted vaccination behaviour. Participants consider COVID-19 information from health professionals, government websites, and World Health Organization as the most trusted information sources. The findings highlight that healthcare decision-makers and university administrators need to monitor students' hesitancy with vaccination to improve students' promotion of the vaccination to the general population.

Nurses' competency in electrocardiogram interpretation in acute care settings: A systematic review

AIMS

Identify and synthesize evidence of nurses' competency in electrocardiogram interpretation in acute care settings.

DESIGN

Systematic mixed studies review.

DATA SOURCES

Cumulative Index to Nursing and Allied Health Literature, Medline, Scopus and Cochrane were searched in April 2021.

REVIEW METHODS

Data were selected using the updated Preferred Reporting Items for Systematic Reviews and Meta-Analysis framework. A data-based convergent synthesis design using qualitative content analysis was adopted. Quality appraisal was undertaken using validated tools appropriate to study designs of the included papers.

RESULTS

Forty-three papers were included in this review. Skills and attitudes were not commonly assessed, as most studies referred to 'competency' in the context of nurses' knowledge in electrocardiogram interpretation. Nurses' knowledge levels in this important nursing role varied notably, which could be partly due to a range of assessment tools being used. Several factors were found to influence nurses' competency in electrocardiogram interpretation across the included studies from individual, professional and organizational perspectives.

CONCLUSION

The definition of 'competency' was inconsistent, and nurses' competency in electrocardiogram interpretation varied from low to high. Nurses identified a lack of regular training and insufficient exposure in electrocardiogram interpretation. Hence, regular, standard training and education are recommended. Also, more research is needed to develop a standardized and comprehensive electrocardiogram interpretation tool, thereby allowing educators to safely assess nurses' competency.

IMPACT

This review addressed questions related to nurses' competency in electrocardiogram interpretation. The findings highlight varying competency levels and assessment methods. Nurses reported a lack of knowledge and confidence in interpreting electrocardiograms. There is an urgent need to explore opportunities to promote and maintain nurses' competency in electrocardiogram interpretation.

Pressure injury prevalence and risk factors in Chinese adult intensive care units: A multi-centre prospective point prevalence study

Despite increasing preventive efforts, pressure injury still occurs in intensive care patients. This study was aimed to describe pressure injury prevalence, risk factors, and prevention practices in adult intensive care patients. This was a multi-centre, one-day, prospective point prevalence study in which a total of 198 intensive care units from 21 provinces in China participated. Overall and ICU-acquired prevalence in intensive care patients were 12.26% and 4.31%, respectively. Consistent with earlier reports, almost half of the ICU-acquired pressure injuries were at stage I, one-fourth were at stage 2, and the most common body sites for pressure injuries were sacral and heel region. Risk factors identified were consistent with prior studies. Repositioning was the most commonly used pressure injury prevention strategy, followed by alternating pressure mattresses/overlays, floating heels, and air-filled mattresses/overlays. These reflect a good level of adherence to recommended international pressure injury prevention clinical practice guidelines. The results provide a baseline reference for overall and ICU-acquired prevalence among adult intensive care patients in China. Future research on what contributed to the lower pressure injury incidence in China needs to be conducted to inform healthcare organisations on their future preventive strategies for pressure injury prevention.

Patient and family perceptions and experiences of same-day discharge following percutaneous coronary intervention and those kept overnight

OBJECTIVE

To explore perceptions and experiences of patients discharged the same day (or not) and their family members towards same-day discharge following percutaneous coronary intervention.

DESIGN AND METHODS

A qualitative interpretative design. Semi-structured phone interviews were conducted with consented patients who underwent percutaneous coronary intervention, and their family members (n = 23). Data were analysed using a content analysis approach.

SETTING

This study was undertaken in the cardiac services department of an Australian tertiary hospital.

MAIN OUTCOME MEASURES

Perceptions and experiences of same-day discharge.

FINDINGS

A total of 31 patients and 23 family members were interviewed. Two categories emerged from the analysis: communication challenges with hospital staff and perceptions of same-day discharge. Family members were often not provided discharge instructions, and some same-day discharged patients felt vulnerable following discharge. When asked, most participants perceived same-day discharge as a preferred option because of its comfort and convenience. Some expressed uncertainty towards same-day discharge due to feeling anxious and apprehensive. Others misperceived same-day discharge as a signal that their heart problem was fixed without realising their underlying chronic health conditions.

CONCLUSION

Most patients and family members perceived same-day discharge as a preferred option. However, strategies are needed to support their transition from hospital to home, therefore, recognising and improving their long-term disease management.

Patient involvement in surgical wound care research: A scoping review

Active involvement of patients in planning, conducting, and disseminating research has been adopted by many organisations internationally, but the extent to which this occurs in surgical wound care is not evident. This scoping review aimed to identify how patients have been involved in surgical wound care research and the quality of its reporting. Full-text studies focused on preoperative and postoperative surgical wound care in the acute care setting, published in English between 2004 and 2019, were included in the review. Screening, data charting, and quality assessment were conducted by two reviewers independently, adjudicated by a third, and then reviewed by five others. Thematic analysis synthesised the findings. Of the eight included studies, seven explained the methods for patient involvement and five described aims related to patient involvement and commented on patient involvement in the discussion. None met all of the quality assessment criteria. Three themes emerged: involvement in modifying and refining research processes, connecting and balancing expert and patient views, and sharing personal insights. Recommendations to improve patient involvement in surgical wounds research include the following: using framework and tools to inform future research; training researcher and patients in their respective research roles; and ongoing monitoring of patient involvement.

Facilitating the relocation of an intensive care unit from shared room to single room setting: Staff perceptions on the effectiveness of a multicomponent intervention

BACKGROUND

Current strategies for new and redesigned intensive care units (ICUs) involve incorporation of single occupancy rooms. These changes have largely been made for infection control and patient privacy reasons. However, there is limited literature available on how to manage the transition of an ICU from shared room to a single room environment.

AIMS

The aim of this study was to evaluate staff members' perceived effectiveness of a multicomponent intervention to facilitate transition from a shared to a single room setting.

METHODS

This qualitative study was conducted in a 20-bed ICU of an Australian tertiary teaching hospital. In total, 24 staff members were interviewed in five groups and five individual interviews 6 months after the ICU relocation.

FINDINGS

Three themes emerged from data analysis: (1) facilitating staff members' transition and engagement during relocation planning; (2) simulating new work processes for the single room setting; and (3) supporting nurses working in the single rooms. The components of the intervention, including the change agent, the relocation working party, Assistance, Coordination, Contingency, Education, Supervision, and Support nurse rounding model, and the safe single room model, were perceived as important strategies to support the relocation transition. The regular newsletter and the information dissemination strategy informed by the social networking survey were viewed to improve communication. Staffing levels and education models that are suitable for the single room setting were identified as areas for improvement.

DISCUSSION AND CONCLUSION

A systematic change management approach, clear communication, staff engagement, and continuously monitoring new work processes are important strategies to ensure the success of the relocation. Delivery of education in the clinical area needs to be further explored to ascertain the impact of a single room environment on its delivery. Intervention co-creation involving research team members and the clinical staff was important in building change management capacity, which may contribute to intervention sustainability and continued clinical practice improvement.

Identification of soil heavy metal sources from anthropogenic activities and pollution assessment of Fuyang County, China

Understanding regional variations of soil heavy metals and their anthropogenic influence are very important for environmental planning. In this study, 286 surface soil samples were collected in Fuyang county, and the 'total' metals for copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd) and nickel (Ni) were measured in 2005. Statistic analysis showed that Cu, Zn, Pb and Cd had been added by exterior factors, and Ni was mainly controlled by natural factors. The combination of multivariate statistical and geostatistical analysis successfully grouped three groups (Cu, Zn and Pb; Cd; and Ni) of heavy metals from different sources. Through pollution evaluation, it was found that 15.76% of the study area for Cu, Zn and Pb, and 46.14% for Cd suffered from moderate or severe pollution. Further spatial analysis identified the limestone mining activities, paper mills, cement factory and metallurgic activities were the main sources for the concentration of Cu, Zn, Pb and Cd in soils, and soil Ni was mainly determined by the parent materials.

Protein kinase C pathway is involved in regulating the secretion of prostatic acid phosphatase in human prostate cancer cells

The stimulated secretion of prostatic acid phosphatase (PAcP) has been known to be a hallmark of androgen action on human prostate epithelial cells for the last five decades. The molecular mechanism of androgen action on PAcP secretion, however, has remained mostly unknown. We investigated the molecular mechanism that promotes PAcP secretion in LNCaP human prostate carcinoma cells which express PAcP and are androgen-responsive. Treatment with 12-o-tetradecanoyl phorbol-13-acetate (TPA), a protein kinase C (PKC) activator, resulted in an increased secretion of PAcP in a dose- and time-dependent fashion. 4Alpha-phorbol, a biologically inactive isomer of TPA, had no effect. This TPA stimulation of PAcP secretion was observed 2 h after exposure, while TPA did not have a significant effect on the mRNA level even with a 6 h treatment. A23187 calcium ionophore, known to mobilize cellular calcium which is a co-factor of PKC, also activated PAcP secretion. This TPA stimulation of PAcP secretion was more potent than the conventional stimulating agent 5alpha-dihydrotestosterone (DHT) at the same concentration of 50 nM. Furthermore, the action of TPA and DHT on PAcP secretion was blocked by five different PKC inhibitors. Results also showed that DHT, as well as TPA, could rapidly modulate PKC activity. Therefore, PKC can regulate PAcP secretion, and may also be involved in DHT action on PAcP secretion.

Decreased expression of cellular prostatic acid phosphatase increases tumorigenicity of human prostate cancer cells

PURPOSE

Understanding cell proliferation regulation in hormone refractory prostate cancer may provide answers for novel solutions. Protein tyrosine phosphatases have been thought to have key roles in regulating cell proliferation and be involved in oncogenesis, although to our knowledge their functional roles in human prostate cancer remain unknown. Human prostatic acid phosphatase (PAcP), a major phosphatase in prostate epithelium, has been shown to function as a neutral protein tyrosine phosphatase in these cells. We evaluated the biological significance of cellular prostatic acid phosphatase expression in human prostate cancer cells.

MATERIALS AND METHODS

Immunohistochemical testing of human prostate cancer archival specimens was done to evaluate the expression of cellular PAcP. Immunoprecipitation and immunoblotting were performed to determine cellular PAcP and SH2 domain-bearing tyrosine phosphatase-1 levels as well as tyrosine phosphorylation of c-ErbB-2/neu in different human prostate cancer cells. The biological behavior of LNCaP derivative sublines was characterized in vitro and in vivo by soft agar analysis and xenograft animal inoculation.

RESULTS

Immunohistochemical staining of human prostate clearly showed that cellular levels of PAcP significantly decreases in prostate cancer cells (p <0.001). The results of biochemical characterization revealed that the cellular level of PAcP but not SHP-1, another differentiation associated protein tyrosine phosphatase, consistently correlated negatively with the growth of several human prostate cancer cell lines. Reintroducing cellular PAcP activity in prostate cancer cells by PAcP complementary DNA transfection resulted in decreased tyrosine phosphorylation of c-ErbB-2/neu, decreased proliferation rates in culture as well as decreased anchorage independent growth in soft agar. The xenograft animal model demonstrated that a higher tumor growth rate as well as larger size is associated with a lower level of cellular PAcP.

CONCLUSIONS

Cellular PAcP can down-regulate prostate cancer cell growth, at least partially by dephosphorylating c-ErbB-2/neu. Therefore, decreased cellular PAcP expression in cancer cells may be involved in prostate cancer progression.

Differential responsiveness of prostatic acid phosphatase and prostate-specific antigen mRNA to androgen in prostate cancer cells

Androgens regulate the expression of both human prostatic acid phosphatase (PAcP) and prostate-specific antigen (PSA), two major prostate epithelium-specific differentiation antigens. Due to the important role of these two enzymes as prostate epithelium differentiation markers, we investigated their regulation of expression at the mRNA level in LNCaP human prostate carcinoma cells. Interestingly, phenol red, a pH indicator in the culture medium, promoted cell growth. To eliminate this non-specific effect, a phenol red-free, steroid-reduced medium was utilized. When high-density cells were grown in that medium, 5alpha-dihydrotestosterone (DHT) suppressed PAcP but stimulated PSA. However, tumor promoter phorbol ester 12-o-tetradecanoyl phorbol-13-acetate (TPA) functioned as a potent inhibitor of both PAcP and PSA expression. Prolonged treatment with DHT as well as TPA resulted in a similar down-regulation of protein kinase C and cellular PAcP activities. Thus, the levels of PAcP and PSA mRNA are differentially regulated by androgens in LNCaP cells.

Expression of receptor protein tyrosine phosphatase alpha mRNA in human prostate cancer cell lines

Receptor protein tyrosine phosphatase alpha (RPTPalpha) is a transmembrane protein phosphatase, and has been proposed to be involved in the differentiation of the neuronal system. In the present study, we demonstrated the expression of RPTPalpha mRNA in several normal human tissues. We further investigated the regulation of expression of RPTPalpha mRNA in epithelial cells utilizing three commercially available human prostate cancer cell lines LNCaP, PC-3 and DU145. This is because these cells exhibit different levels of differentiation, defined by the expression of a tissue-specific differentiation antigen, prostatic acid phosphatase (PAcP), and their androgen sensitivity. LNCaP cells express PAcP and are androgen-sensitive cells, while PC-3 and DU145 cells do not express PAcP and are androgen-insensitive cells. Northern blot analyses revealed that, in LNCaP cells, fetal bovine serum (FBS) and 5alpha-dihydrotestosterone (DHT) down-regulates RPTPalpha mRNA expression, similar to the effect on PAcP. Contrarily, FBS up-regulated the RPTPalpha mRNA level in PC-3 and DU145 cells. In LNCaP cells, sodium butyrate inhibited cell growth and up-regulated RPTPalpha as well as PAcP mRNA expression. Although, sodium butyrate also inhibited the growth of PC-3 and DU145 cells, the level of RPTPalpha mRNA was decreased in PC-3, while increased in DU145 cells. Thus, data taken together indicate that the expression of RPTPalpha is apparently regulated by a similar mechanism to that of PAcP in LNCaP cells.

SIB-1757 and SIB-1893: selective, noncompetitive antagonists of metabotropic glutamate receptor type 5

Cell lines expressing the human metabotropic glutamate receptor subtype 5a (hmGluR5a) and hmGluR1b were used as targets in an automated high-throughput screening (HTS) system that measures changes in intracellular Ca2+ ([Ca2+]i) using fluorescence detection. This functional screen was used to identify the mGluR5-selective antagonist, SIB-1757 [6-methyl-2-(phenylazo)-3-pyridinol], which inhibited the glutamate-induced [Ca2+]i responses at hmGluR5 with an IC50 of 0.37 microM compared with an IC50 of >100 microM at hmGluR1. Schild analysis demonstrated a noncompetitive mechanism of inhibition. Pharmacophore mapping was used to identify an additional compound, SIB-1893 [(E)-2-methyl-6-(2-phenylethenyl)pyridine], which was also shown to block glutamate-induced increases in [Ca2+]i at hmGluR5 with an IC50 of 0.29 microM compared with an IC50 of >100 microM at hmGluR1. SIB-1757 and SIB-1893 showed little or no activity when tested for agonist and antagonist activity at the other recombinant human mGluR subtypes, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, and N-methyl-D-aspartate receptors. In rat neonatal brain slices, SIB-1757 and SIB-1893 inhibited (S)-3,5-dihydroxyphenylglycine (DHPG)-evoked inositol phosphate accumulation in hippocampus and striatum by 60% to 80%, with a potency similar to that observed on recombinant mGluR5. However, in the cerebellum, a brain region with low mGluR5 expression, SIB-1757 failed to inhibit DHPG-evoked inositol phosphate accumulation. In cultured rat cortical neurons, SIB-1757 and SIB-1893 largely inhibited DHPG-evoked [Ca2+]i signals, revealing a population of neurons that were less sensitive to SIB-1757 and SIB-1893. This is the first description of highly selective, noncompetitive mGluR5 antagonists. These compounds will be useful tools in evaluating the role of mGluR5 in normal physiology and in animal models of disease.

The human N-methyl-D-aspartate receptor 2C subunit: genomic analysis, distribution in human brain, and functional expression

cDNAs encoding four isoforms of the human NMDA receptor (NMDAR) NMDAR2C (hNR2C-1, -2, -3, and -4) have been isolated and characterized. The overall identity of the deduced amino acid sequences of human and rat NR2C-1 is 89.0%. The sequences of the rat and human carboxyl termini (Gly925-Val1,236) are encoded by different exons and are only 71.5% homologous. In situ hybridization in human brain revealed the expression of the NR2C mRNA in the pontine reticular formation and lack of expression in substantia nigra pars compacta in contrast to the distribution pattern observed previously in rodent brain. The pharmacological properties of hNR1A/2C were determined by measuring agonist-induced inward currents in Xenopus oocytes and compared with those of other human NMDAR subtypes. Glycine, glutamate, and NMDA each discriminated between hNR1A/2C-1 and at least one of hNR1A/2A, hNR1A/2B, or hNR1A/2D subtypes. Among the antagonists tested, CGS 19755 did not significantly discriminate between any of the four subtypes, whereas 5,7-dichlorokynurenic acid distinguished between hNR1A/2C and hNR1A/2D. Immunoblot analysis of membranes isolated from HEK293 cells transiently transfected with cDNAs encoding hNR1A and each of the four NR2C isoforms indicated the formation of heteromeric complexes between hNR1A and all four hNR2C isoforms. HEK293 cells expressing hNR1A/ 2C-3 or hNR1A/2C-4 did not display agonist responses. In contrast, we observed an agonist-induced elevation of intracellular free calcium and whole-cell currents in cells expressing hNR1A/2C-1 or hNR1A/2C-2. There were no detectable differences in the macroscopic biophysical properties of hNR1A/2C-1 or hNR1A/2C-2.

Expression of human prostatic acid phosphatase correlates with androgen-stimulated cell proliferation in prostate cancer cell lines

Androgen plays a critical role in regulating the growth and differentiation of normal prostate epithelia, as well as the initial growth of prostate cancer cells. Nevertheless, prostate carcinomas eventually become androgen-unresponsive, and the cancer is refractory to hormonal therapy. To gain insight into the mechanism involved in this hormone-refractory phenomenon, we have examined the potential role of the androgen receptor (AR) in that process. We have investigated the expression of AR and two prostate-specific androgen-responsive antigens, prostatic acid phosphatase (PAcP) and prostate-specific antigen (PSA), for the functional activity of AR in LNCaP and PC-3 human prostate carcinoma cells. Our results are as follows. (i) Clone 33 LNCaP cells express AR, PAcP, and PSA, and cell growth is stimulated by 5alpha-dihydrotestosterone (DHT). Stimulation of cell growth correlates with decreased cellular PAcP activity. (ii) In clone 81 LNCaP cells, the expression of PAcP decreases with a concurrent decrease in the degree of androgen stimulation of cell growth, whereas the expression of PSA mRNA level is up-regulated by DHT, as in clone 33 cells. Conversely, in PAcP cDNA-transfected clone 81 cells, an additional expression of cellular PAcP correlates with an increased stimulation by androgen, higher than the corresponding control cells. (iii) PC-3 cells express a low level of functional AR with no detectable PAcP or PSA, and the growth of PC-3 cells is not affected by DHT treatment. Nevertheless, in two PAcP cDNA-transfected PC-3 sublines, the expression of exogenous cellular PAcP correlates with androgen stimulation. This androgen stimulation of cell growth concurs with an increased tyrosine phosphorylation of a phosphoprotein of 185 kDa. In summary, the data indicate that the expression of AR alone is not sufficient for androgen stimulation of cell growth. Furthermore, in AR-expressing prostate cancer cells, the expression of cellular PAcP correlates with androgen stimulation of cell proliferation.

Cloning and stable expression of the mGluR1b subtype of human metabotropic receptors and pharmacological comparison with the mGluR5a subtype

We isolated and characterized a cDNA encoding the human metabotropic glutamate receptor subtype 1b (hmGluR1b). In situ hybridization studies in human brain regions revealed a higher distribution of mGluR1 mRNA in the dentate gyrus of the hippocampus, the substantia nigra pars compacta and the Purkinje cell layer of the cerebellum compared to other regions studied. We established stable expression of recombinant hmGluR1b in L(tk-) mouse fibroblast and Chinese hamster ovary (CHO-dhfr-) cells. In both expression systems, agonist activation of hmGluR1b stimulated inositol phosphate (InsP) formation and elevation of the cytosolic free calcium ([Ca2+]i), and both responses were blocked by (S)-MCPG. The rank order of potency for agonists was quisqualate > glutamate > (1S,3R)-ACPD in both expression systems. Comparison of the agonist profiles of hmGluR1b and hmGluR5a, both stably expressed in L(tk-) cells, indicated the same rank order of potency (quisqualate > glutamate > or = (RS)-3,5-DHPG > or = (1S,3R)-ACPD), but each of the four agonists were more potent on hmGluR5a than on hmGluR1b. In antagonist studies, (S)-MCPG inhibited the agonist-induced InsP formation and elevation of [Ca2+]i in both hmGluR1b- and hmGluR5a-expressing cells. (S)-4CPG and (S)-4C3HPG both inhibited agonist responses only in hmGluR1b-expressing cells. However, in hmGluR5a-expressing cells the antagonist activity of (S)-4CPG and (S)-4C3HPG was dependent on the agonist used in the study, since they inhibited responses to glutamate but not to quisqualate. Stable cell lines expressing specific subtypes of human mGluRs represent valuable tools for the study of the mechanism of action of mGluRs at the molecular and cellular level and as screening targets for identification of subtype-selective agonists or antagonists.

The expression of prostatic acid phosphatase is transcriptionally regulated in human prostate carcinoma cells

The expression of prostatic acid phosphatase (PAcP) in three human prostate carcinoma cell lines including LNCaP, DU 145 and PC-3, was studied to explore its potential role as a marker in the progression of prostate cancer. Although Southern blot analysis suggested the presence of PAcP gene in all three prostate carcinoma cell lines, the Northern blot analysis and the reverse transcriptase-polymerase chain reaction (RT-PCR) assay showed that PAcP mRNA can be detected only in LNCaP cells. As one of the major differences between LNCaP cells and PC-3 as well as DU 145 cells is the androgen-sensitivity of LNCaP cells, we then focused on the influence of PAcP expression by the presence of androgen receptor (AR) in human AR cDNA-transfected PC-3 cells and high passages of LNCaP cells. The results demonstrated that the transfection of human AR cDNA into PC-3 cells did not have any detectable effect on the expression of PAcP. Further, in LNCaP cells, while the level of PAcP mRNA diminished upon passage, the AR mRNA level remained approximately the same. Together, these data suggested that the differential expression of PAcP in different prostate carcinoma cells including high passages of LNCaP cells may occur at the transcriptional level and may have little linkage to the expression of AR.

Growth inhibition of androgen-insensitive human prostate carcinoma cells by a 19-norsteroid derivative agent, mifepristone

Mifepristone, also known as RU 486, is a 19-norsteroid derivative. Currently, mifepristone is being tested in clinical trials on meningioma and breast cancer. In this study we analyzed whether mifepristone could inhibit the growth of human prostate cancer cells including androgen-insensitive (PC-3 and DU145) and androgen-sensitive (LNCaP) cell lines. At 1-nM concentration, mifepristone exhibited a marginal stimulatory action on LN-CaP and PC-3 cells. Nevertheless, a dose-dependent growth inhibition on those same cell lines was observed at concentrations of 1 microM and 10 microM. Twenty-day exposure to the clinically achievable concentration of 1 microM mifepristone resulted in consistent inhibition of all three cell lines studied. Furthermore, this in vitro growth inhibition was reflected in an in vivo nude mouse system. Mifepristone at the dosage of 4 mg/100 g body weight completely suppressed the growth of PC-3 tumors for 21 days, although this was followed by a growth rate similar to that of the control tumor. To understand the possible mechanism of mifepristone inhibition, PC-3 cells were exposed to mifepristone in comparison with dexamethasone (Dex), progesterone, and 5 alpha-dihydrotestosterone (DHT), each at 1-microM concentration. The results demonstrated that while both DHT and Dex alone had essentially no effect on cell growth, progesterone alone resulted in a 20% growth inhibition, while mifepristone had more than 60% inhibition with a 16-day exposure. At an equal concentration, the degree of growth inhibition of PC-3 cells by mifepristone or progesterone was partially diminished by simultaneous exposure to Dex. In conclusion, our results demonstrated that the growth of androgen-insensitive prostate cancer cells can be directly inhibited by mifepristone in cultures. This in vitro inhibition is reflected in xenografted tumors.

The cellular level of prostatic acid phosphatase and the growth of human prostate carcinoma cells

Prostatic acid phosphatase (PAcP) is a prostate epithelium-specific differentiation antigen. It has been demonstrated that human PAcP exhibits endogenous protein tyrosine phosphatase (PYP) activity, and that it represents the major PYP activity in normal prostate cells. Thus, it has been postulated that cellular PAcP may play a role in the tyrosine phosphorylation-mediated signal transduction. In this paper, we used LNCaP human prostate carcinoma cells, which express the endogenous PAcP, to study changes in cellular PAcP activity during cell growth. Our results demonstrated that PAcP activity increased when the cells reached confluence. Stimulation of cell growth by fresh culture medium or 5 alpha-dihydrotestosterone (DHT), a classical stimulator of prostate epithelial growth, resulted in a decline in PAcP activity. Moreover, transfection of PC-3 cells, which do not express PAcP, with a PAcP-expressing vector led to diminished cellular growth rate. These data established an inverse relationship between the cellular level of PAcP and the cell growth rate, suggesting that PAcP may be involved in regulating the growth of human prostate carcinoma cells.