Release of a soluble ATPase from the rabbit isolated vas deferens during nerve stimulation

The properties of the ATPase released during electrical field stimulation (EFS) (8 Hz, 25 s) of the sympathetic nerves of the superfused rabbit isolated vas deferens were investigated. Superfusate collected during EFS rapidly metabolised exogenous ATP (100 microM) and 50% was broken down in 5.67+/-0.65 min. The main metabolite was ADP, virtually no AMP was produced and adenosine was absent. No enzyme activity was seen in samples collected in the absence of EFS. Lineweaver-Burke analysis of the initial rates of ATP hydrolysis gave a K(M) of 40 microM and V(max) of 20.3 nmol ATP metabolized min(-1) ml(-1) superfusate. ATPase activity was unaffected by storage at room temperature for 24 h, but was abolished at pH4 or by heating at 80 degrees C for 10 min. ARL 67156 inhibited ATP breakdown in a concentration-dependent manner (IC(50)=25 microM (95% confidence limits=22-27 microM), Hill slope=-1.06+/-0.04). When EFS was applied three times at 30 min intervals, ATP metabolism was 20-30% less in superfusate collected during the second and third stimulation periods compared with the first. ATPase activity was released in a frequency-dependent manner, with significantly greater activity seen after stimulation at 4 and 8 Hz than at 2 Hz. In conclusion, EFS of the sympathetic nerves in the rabbit vas deferens causes release of substantial ATPase, but little ADPase activity into the extracellular space. This contrasts with the guinea-pig vas deferens, which releases enzymes that degrade ATP to adenosine. Thus, the complement of enzymes released by nerve stimulation is species-dependent.

Examining television as an influence on children's health behaviors

This article is a review of select empirical research studies examining television as an influence on children's health behaviors. The reader is first provided with an overview of the research on the role of television in children's lives. This is followed by an in-depth presentation of the research related to television content and its effect on risk-taking and the role of television commercials and their influence on nutrition and dietary behaviors.

The utility of polysporin ointment in the eradication of methicillin-resistant Staphylococcus aureus colonization: a pilot study

We evaluated the efficacy of an ointment containing bacitracin, polymyxin B, and gramicidin for the eradication of colonization by methicillin-resistant Staphylococcus aureus in 11 medical patients, 10 (91%) of whom had previously failed a 1-week course of topical mupirocin. Mupirocin resistance was documented in 5 (45%) of 11 patients. Successful decolonization was achieved in 9 (82%) of 11 patients (based on 2 months of follow-up).

The discovery and development of P2 receptor subtypes

Extracellular purine and pyrimidine nucleotides modulate cellular activity by acting at P2 receptors. The first receptor to be identified was the P(2)-purinoceptor, which was characterised and named in 1978. In the 1980s this site was subdivided into P(2X) and P(2Y) purinoceptors on the basis of pharmacological criteria in functional studies on native receptors. Subsequently, a similar approach led to the characterisation of the P(2T), P(2Z), P(2U) and P(2D) purinoceptors. In the 1990s a molecular biological approach has led to the cloning and functional expression of at least 12 mammalian P2 receptor subtypes. The challenge now is to relate these recombinant receptors to native receptors present within a wide range of tissues.

A community-based approach to evaluation of health outcomes and costs for telepsychiatry in a rural population: preliminary results

A pilot trial was established to support visiting psychiatric services and local public and private practitioners through the use of videoconferencing. The purpose of the trial was to determine whether people in the community received better health-care with telemedicine. A community-based approach was used to evaluate health outcomes, costs, utilization, accessibility, quality and needs for such services in a rural community in Queensland. Over a two-year period data were collected from 124 subjects who met the criteria of having a mental health problem or mental disorder. Nine further subjects refused to participate in the study. Only 32 subjects used videoconferencing to receive mental health services. Preliminary results did not show any significant improvements in wellbeing or quality of life, although the time span was relatively short. However, the results confirmed that the people were no worse off from a consumer or a practitioner perspective from using videoconferencing. Most consumers found that videoconferencing with a psychiatrist moderately or greatly helped them in managing their treatment, with 98% of them preferring to be offered videoconferencing in combination with local services. Overall, videoconferencing is a crucial part of enhancing psychiatry services in rural areas. However, it is not necessarily cost-effective for all consumers, general practitioners, psychiatrists, or the public mental health service.

Standardized quantitative assessment of brain tumor survivors treated within clinical trials in childhood

Important morbidity and impairment of life quality arises from both the primary pathology and therapeutic interventions in children with central nervous system (CNS) tumors. Standardized and systematic collection of morbidity data is a prerequisite of clinical trials in this field. The perception of the survivor is paramount in the determination of quality of life as this variable is dependent on the beholder. Comprehensive assessment of outcome following therapeutic intervention should evaluate this in parallel with other physical and psycho-social outcome parameters. A structured, simple schema for the evaluation of survivors of childhood CNS tumors is presented. It is intended to be easily applicable by clinicians within the everyday clinical setting. Information relating to pre- and post-operative states, function, health status and emotional and psychological well-being is collected at regular intervals from diagnosis. Re-integration into society and independence are evaluated. Children self-complete health-status assessments where appropriate. Evidence to support this is presented. The schema is intended to provide a basic framework for the monitoring of health status following treatment of CNS tumors in childhood. Regular assessments may identify individuals in need of more detailed investigation and further understanding of the evolution of morbidity in this cohort. Survivors' perception of the impact of documented dysfunction on their health-related quality of life will be determined. Optimization of the planning of future clinical service provision and therapies will result.

HIV as a chronic disease: implications for long-term care at an AIDS-dedicated skilled nursing facility

OBJECTIVE

To describe the characteristics and outcomes of the first 3 years of admissions to a dedicated skilled nursing facility for people with acquired immunodeficiency syndrome (AIDS).

METHODS

Systematic chart review of consecutive admissions to a 30-bed, AIDS-designated long-term care facility in New Haven, Connecticut, from October 1995 through December 1998.

RESULTS

The facility has remained filled to 90% or more of its bed capacity since opening. Of 180 patients (representing 222 admissions), 69% were male; mean age was 41 years; 57% were injection drug users; 71% were admitted directly from a hospital. Leading reasons for admission were (1) the need for 24-hour nursing/medical supervision, (2) completion of acute medical treatment, and (3) terminal care. On admission, the median Karnofsky score was 40, and median CD4+ cell count was 24/mm3; 48% were diagnosed with serious neurologic disease, 44% with psychiatric illness; patients were receiving a median of 11 medications on admission. Of 202 completed admissions, 44% of patients died, 48% were discharged to the community, 8% were discharged to a hospital. Median length of stay was 59 days (range 1 to 1,353). Early (< or = 6 months) mortality was predicted by lower admission CD4+ count, impairments in activities of daily living, and the absence of a psychiatric history; long-term stay (> 6 months) was predicted by total number of admission medications, neurologic disease, and dementia. Comparison of admissions from 1995 to 1996 to those in 1997 to 1998 indicated significantly decreased mortality rates and increased prevalence of psychiatric illness between the two periods (P < .01).

CONCLUSIONS

A dedicated skilled nursing facility for people with AIDS can fill an important service need for patients with advanced disease, acute convalescence, long-term care, and terminal care. The need for long-term care may continue to grow for patients who do not respond fully to current antiretroviral therapies and/or have significant neuropsychiatric comorbidities. This level of care may be increasingly important not only in reducing lengths of stay in the hospital, but also as a bridge to community-based residential options in the emerging chronic disease phase of the AIDS epidemic.

P2Y receptor-mediated inhibition of tumor necrosis factor alpha -stimulated stress-activated protein kinase activity in EAhy926 endothelial cells

In the EAhy926 endothelial cell line, UTP, ATP, and forskolin, but not UDP and epidermal growth factor, inhibited tumor necrosis factor alpha (TNFalpha)- and sorbitol stimulation of the stress-activated protein kinases, JNK, and p38 mitogen-activated protein (MAP) kinase, and MAPKAP kinase-2, the downstream target of p38 MAP kinase. In NCT2544 keratinocytes, UTP and a proteinase-activated receptor-2 agonist caused similar inhibition, but in 13121N1 cells, transfected with the human P2Y(2) or P2Y(4) receptor, UTP stimulated JNK and p38 MAP kinase activities. This suggests that the effects mediated by P2Y receptors are cell-specific. The inhibitory effects of UTP were not due to induction of MAP kinase phosphatase-1, but were manifest upstream in the pathway at the level of MEK-4. The inhibitory effect of UTP was insensitive to the MEK-1 inhibitor PD 098059, changes in intracellular Ca(2+) levels, or pertussis toxin. Acute phorbol 12-myristate 13-acetate pretreatment also inhibited TNFalpha-stimulated SAP kinase activity, while chronic pretreatment reversed the effects of UTP. Furthermore, the protein kinase C inhibitors Ro318220 and Go6983 reversed the inhibitory action of UTP, but GF109203X was ineffective. These results indicate a novel mechanism of cross-talk regulation between P2Y receptors and TNFalpha-stimulated SAP kinase pathways in endothelial cells, mediated by Ca(2+)-independent isoforms of protein kinase C.

ATP, an agonist at the rat P2Y(4) receptor, is an antagonist at the human P2Y(4) receptor

The nucleotide selectivities of the human P2Y(4) (hP2Y(4)) and rat P2Y(4) (rP2Y(4)) receptor stably expressed in 1321N1 human astrocytoma cells were determined by measuring increases in intracellular [Ca(2+)] under conditions that minimized metabolism, bioconversion, and endogenous nucleotide release. In cells expressing the hP2Y(4) receptor, UTP, GTP, and ITP all increased intracellular [Ca(2+)] with a rank order of potency of UTP (0.55) > GTP (6.59) = ITP (7.38), (EC(50), microM). ATP, CTP, xanthine 5'-triphosphate (XTP), and diadenosine 5',5"'-P(1), P(4)-tetraphosphate (Ap(4)A), all at 100 microM, were inactive at the hP2Y(4) receptor. In cells expressing the rP2Y(4) receptor, all seven nucleotides increased intracellular [Ca(2+)] with similar maximal effects and a rank order of potency of UTP (0.20) > ATP (0. 51) > Ap(4)A (1.24) approximately ITP (1.82) approximately GTP (2. 28) > CTP (7.24) > XTP (22.9). Because ATP is inactive at the hP2Y(4) receptor, we assessed whether ATP displayed antagonist activity. When coapplied, ATP shifted the concentration-response curve to UTP rightward in a concentration-dependent manner, with no change in the maximal response. A Schild plot derived from these data gave a pA(2) value of 6.15 (K(B) = 708 nM) and a slope near unity. Additionally, CTP and Ap(4)A (each at 100 microM) inhibited the response to an EC(50) concentration of UTP by approximately 40 and approximately 50%, respectively, whereas XTP had no effect. The inhibitory effects of ATP, CTP, and Ap(4)A were reversible on washout. Thus, ATP is a potent agonist at the rP2Y(4) receptor but is a competitive antagonist with moderate potency at the hP2Y(4) receptor.

Characterization of the ATPase released during sympathetic nerve stimulation of the guinea-pig isolated vas deferens

The release of ATPase activity evoked by electrical field stimulation (EFS) (8 Hz, 25 s) was investigated in several tissues in which adenosine 5'-triphosphate (ATP) acts as a neurotransmitter. Superfusate collected during EFS of sympathetic nerves of the guinea-pig, rat and mouse isolated vas deferens and parasympathetic nerves of the guinea-pig isolated urinary bladder contained ATPase activity. ATP breakdown was fastest in superfusate collected from the guinea-pig isolated vas deferens. However, EFS of the enteric nerves of the guinea-pig isolated taenia coli did not release any detectable ATPase. The ATPase released from the guinea-pig isolated vas deferens metabolized ATP at similar rates at incubation temperatures of 37 degrees C and 20 degrees C. Lineweaver-Burke analysis of the initial rates of ATP hydrolysis gave a K(M) of 39 microM and a V(max) of 1039 pmol ATP metabolized min(-1) ml(-1) superfusate. 6-N,N-diethyl-D-beta,gamma-dibromomethyleneATP (ARL 67156), pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) and pyridoxal-5'-phosphate (P-5-P) all inhibited the ATPase activity in a concentration-dependent manner with a potency order of ARL 67156 = PPADS>P-5-P. In conclusion, EFS of several tissues in which ATP is a neurotransmitter causes the release of an ATPase and activity is greatest in the guinea-pig vas deferens. The enzyme has pharmacological and kinetic characteristics that are similar to ectonucleoside triphosphate diphosphohydrolases.

Mental health service use by Americans with severe mental illnesses

BACKGROUND

The aim of this study was to determine the patterns and determinants of service use in severely mentally ill persons drawn from the National Institute of Mental Health Epidemiological Catchment Area (ECA) program, a community-based epidemiologic survey. This information provides a baseline against which to track ongoing changes in the US mental health service system.

METHODS

Severe mental illness (SMI) was defined according to US Senate Appropriations Committee guidelines. Comparisons were made with persons who had a mental disorder that did not meet these criteria (non-SMI). Sociodemographic factors, and 1-year volume and intensity of mental or addictive services use were determined. Differences between those who used services and those who did not were examined using logistic regression.

RESULTS

Persons with SMI differed from persons with non-SMI in most sociodemographic characteristics. A higher proportion of persons with SMI used ambulatory services, but the mean number of visits per person did not differ from the non-SMI population. Persons with SMI comprised the bulk of hospital inpatients admitted during a 1-year period. Several significant sociodemographic determinants of service use were found, with different patterns for general medical and specialty service use, pointing out potential barriers to care.

CONCLUSIONS

As health care reform measures continue to be debated, attention to the service needs of the severely mentally ill is of crucial importance. Pre-managed care (pre-1993) baseline service use benchmarks will be essential to assess the impact of managed care on access to care, particularly for the severely mentally ill. Periodic collection of epidemiologic data on prevalence and service use would thus greatly facilitate service planning and addressing barriers to receiving mental health services in this population.

The effect of P2 receptor antagonists and ATPase inhibition on sympathetic purinergic neurotransmission in the guinea-pig isolated vas deferens

1. Intracellular microelectrodes were used to record the transmembrane potential and excitatory junction potentials (e.j.p.s) produced by sympathetic nerve stimulation (1 Hz) in smooth muscle cells of the guinea-pig isolated vas deferens. 2. The symmetrical 3'-urea of 8-(benzamido)naphthalene-1,3,5-trisulphonic acid (NF023) produced a concentration-dependent inhibition of e.j.p. magnitude (IC(50)=4. 8x10(-6) M), but had no effect on the resting membrane potential of the smooth muscle cells. 3. Pyridoxal-5-phosphate (P-5-P) also depressed e.j.p. magnitude in a concentration-dependent manner, but was less potent than NF023 (IC(50)=2.2x10(-5) M). At 10(-4) M and above P-5-P significantly depolarized the smooth muscle cells. 4. The nucleoside triphosphatase inhibitor 6-N,N-diethyl-D-beta, gamma-dibromomethyleneATP (ARL 67156) (5x10(-5) M) significantly increased e.j.p. amplitude. ARL 67156 (10(-4) M) further increased e. j.p. amplitude such that they often reached threshold for initiation of action potentials, causing muscle contraction and expulsion of the recording electrode. 5. After reduction of e.j.p.s by NF023 or P-5-P (both 10(-5) M), subsequent co-addition of ARL 67156 (10(-4) M) significantly increased their magnitude. 6. The overflow of endogenous ATP evoked by field stimulation of sympathetic nerves (8 Hz, 1 min) was measured by HPLC and flurometric detection. ARL 67156 (10(-4) M) enhanced ATP overflow by almost 700% compared to control. 7. We conclude that for electrophysiological studies NF023 is preferable to other P2X receptor antagonists such as pyridoxalphosphate -6-azophenyl-2',4'-disulphonic acid (PPADS), suramin or P-5-P. Furthermore, breakdown of endogenous ATP by nucleoside triphosphatases is an important modulator of purinergic neurotransmission in the guinea-pig vas deferens.

HLA and other host factors in transfusion-acquired HIV-1 infection

The host and viral factors that underlie infection with HIV-1 vary considerably with some individuals progressing to AIDS within 3 to 5 years after infection, whereas others remain clinically asymptomatic for over 10 years. Host factors that may contribute to disease progression include HLA and allelic variants of the chemokine receptors CCR5 and CCR2, which have been shown to influence both long-term survival and rapid progression. In this study, we have examined the contribution of HLA and polymorphisms in CCR5 and CCR2 to long-term survival in transfusion-acquired HIV-1-infected individuals. We have found a higher number of HLA-A32 and -A25 alleles but a lower number of the HLA-B8 allele in the study group compared with the frequencies seen in the HIV-1-negative Australian caucasian population. However, there was no apparent contribution by allelic variants of CCR5 and CCR2 to long-term survival and the combined influence of HLA and CCR polymorphisms could not be evaluated in this relatively small (n = 20) group of study subjects. The results of this work support a role for HLA in long-term nonprogression though the presence in the Sydney Blood bank Cohort of nef-defective HIV-1 may confound associations between certain HLA alleles and long-term survival in the face of infection with HIV-1.

Confirmation of the detection of HLA-A*0104N in a family: a PCR-SSP reaction for the allelic detection of HLA-A*0104N

The allele A*0104N has been detected in a family with a patient requiring a bone marrow transplant. The allele was found as a consequence of a discrepant result when family members were typed using serology and polymerase chain reaction using sequence-specific primers (PCR-SSP). Serological typing gave an apparent HLA-A 'blank' while PCR-SSP revealed the presence of an A*01 allele in three family members who were serologically negative for A1. Sequencing-based typing (SBT) was then used to establish that the allele was A*0104N. A PCR-SSP reaction was subsequently designed and used for the allelic detection of A*0104N. The study highlights the potential risks involved if molecular technology is used for typing, unless all non-expressed alleles are specifically detected.

Modulation of purinergic neurotransmission

During the past 25 years ATP has become accepted as an important neurotransmitter at a wide variety of neuroeffector junctions, usually acting as a cotransmitter with NA, ACh, nitric oxide or a neuropeptide such as NPY or VIP. The details of the storage and release of ATP with its cotransmitters has yet to be resolved. However, recent studies indicate that there is more than one population of storage vesicles in the nerves, since the release of the various cotransmitters varies over time and can be differentially modulated by drugs. The subclassification of P2 receptors has advanced dramatically in the past few years due to the use of molecular biology methods allowing the cloning and expression of 14 different subclasses of P2 receptors, seven P2X and seven P2Y. Determination of the functional significance of the various receptor subtypes would be helped by the development of selective agonists and antagonists. The neurotransmitter action of ATP at visceral and vascular smooth muscle P2X receptors has been elucidated in considerable detail. ATP induces a transient inward current via ligand-gated channels, which produces EJPs, action potentials and a phasic contraction of the effector tissue. ATP's neurotransmitter actions appear to be curtailed by the action of ATPases. It has been assumed that this ATPase activity is due to membrane bound ecto-ATPases on the surface of the effector tissue, however, the recently identified soluble ATPase released during nerve stimulation could also be involved in inactivation of ATP. The relative importance of ecto-ATPase and the releasable ATPase is yet to be determined.

Training for telemedicine

All technology requires training. Simply installing videoconferencing equipment in a hospital or health centre, and leaving the manufacturer's manual nearby, is not sufficient to encourage or maintain its use for telemedicine. Presenting clinicians and other users with thick policy and procedure documents to be read and understood is also not helpful. Following initial awareness raising about telemedicine and its potential, staff must be properly trained: not just in how to turn on the equipment but in how to use it effectively for consultation, education and administrative purposes. Training needs to be continual, especially where staff turnover is high. It should be practical, pitched at different levels, incorporated into mainstream activities such as orientation courses and staff development days wherever possible, and supplemented with clear, straightforward protocols and user-friendly instruction manuals.

Identification, sequencing and structural analysis of a nifA-like gene of Acetobacter diazotrophicus

A recombinant plasmid, pAD101, containing a DNA fragment of Acetobacter diazotrophicus strain PAL5 was isolated by its ability to restore Nif+ phenotype to a nifA- ntrC- double mutant of Azotobacter vinelandii. Hybridization with the nifA genes of Azospirillum brasilense located the nifA gene more precisely to specific fragments of pAD101. DNA sequencing of appropriate subclones of pAD101 revealed that the nifA gene was adjacent to the nifB gene in A. diazotrophicus, and the 5' end of the nifB gene was located downstream of the nitrogenase MoFe subunit gene, nifK. The deduced aminoacid sequence of A. diazotrophicus nifA and nifB gene were most similar to the NifA and NifB proteins of Azorhizobium caulinodans and Rhodobacter capsulatus, respectively. In addition, nucleotide sequences upstream of the A. diazotrophicus nifA-encoding region indicate features similar to those in the A. caulinodans nifA promoter region involved in O2 and fixed N regulation of nifA expression.