Development and Validation of a Prediction Model of Prescription Tranquilizer Misuse Based on a Nationally Representative United States Sample

BACKGROUND

Prescription tranquilizer misuse is a risky behavior associated with fatal drug poisonings. Although various predictors have been examined, there is no published prediction model for tranquilizer misuse. This study develops and internally validates a tranquilizer misuse prediction model based primarily on drug histories of participants in a national cross-sectional survey. Predictors also include psychiatric, behavioral and demographic variables.

METHODS

We analyzed data from 471,097 individuals aged 14-to-29-years in the United States, as sampled by the National Survey of Drug Use and Health, 2004-2018, an annual cross-sectional survey. We encoded 21 predictors with known or likely onset prior to tranquilizer misuse initiation, (e.g., early onset of cannabis use). With this dataset, we trained a neural network and regularized logistic regression model. While the assessment for tranquilizer misuse changed slightly in 2015, by pooling all years of survey data, predictions are robust to this source of variation.

RESULTS

1.44% of the pooled sample, 2004-2018, recently initiated tranquilizer misuse (unweighted estimate). On held-out test data (n = 43,714), logistic regression and the neural network performed equally well, with an area under the receiver operating characteristic curve (AUC) of ∼0.83 on the primary model, containing 12 variables known to occur before tranquilizer misuse.

CONCLUSION

Built for case prediction rather than case detection, this model restricted predictors to those with known timing prior to initiation of tranquilizer misuse. Yet its performance supersedes commonly accepted criteria for clinical prediction models (AUC > 0.80). Future work should incorporate survey analysis weights into the prediction model to minimize possible bias.

Activation of TRPV4 by mechanical, osmotic or pharmaceutical stimulation is anti-inflammatory blocking IL-1β mediated articular cartilage matrix destruction

OBJECTIVE

Cartilage health is maintained in response to a range of mechanical stimuli including compressive, shear and tensile strains and associated alterations in osmolality. The osmotic-sensitive ion channel Transient Receptor Potential Vanilloid 4 (TRPV4) is required for mechanotransduction. Mechanical stimuli inhibit interleukin-1β (IL-1β) mediated inflammatory signalling, however the mechanism is unclear. This study aims to clarify the role of TRPV4 in this response.

DESIGN

TRPV4 activity was modulated glycogen synthase kinase (GSK205 antagonist or GSK1016790 A (GSK101) agonist) in articular chondrocytes and cartilage explants in the presence or absence of IL-1β, mechanical (10% cyclic tensile strain (CTS), 0.33 Hz, 24hrs) or osmotic loading (200mOsm, 24hrs). Nitric oxide (NO), prostaglandin E₂ (PGE₂) and sulphated glycosaminoglycan (sGAG) release and cartilage biomechanics were analysed. Alterations in post-translational tubulin modifications and primary cilia length regulation were examined.

RESULTS

In isolated chondrocytes, mechanical loading inhibited IL-1β mediated NO and PGE₂ release. This response was inhibited by GSK205. Similarly, osmotic loading was anti-inflammatory in cells and explants, this response was abrogated by TRPV4 inhibition. In explants, GSK101 inhibited IL-1β mediated NO release and prevented cartilage degradation and loss of mechanical properties. Upon activation, TRPV4 cilia localisation was increased resulting in histone deacetylase 6 (HDAC6)-dependent modulation of soluble tubulin and altered cilia length regulation.

CONCLUSION

Mechanical, osmotic or pharmaceutical activation of TRPV4 regulates HDAC6-dependent modulation of ciliary tubulin and is anti-inflammatory. This study reveals for the first time, the potential of TRPV4 manipulation as a novel therapeutic mechanism to supress pro-inflammatory signalling and cartilage degradation.

Safety of immediate skin-to-skin contact after vaginal birth in vigorous late preterm neonates - A pilot study

BACKGROUND

To evaluate the safety of immediate skin-to-skin contact (SSC) in vigorous late preterm neonates, where observation under radiant warmer is standard of care, in a prospective, randomized, controlled, and equivalence pilot study.

METHODS

Singletons born vaginally at 35-36 6/7 weeks gestation were randomized to initiate immediate SSC or standard of care with continuous pulse oximeter monitoring for the first hour of life.

RESULTS

Forty-seven dyads were randomized to SSC (n = 21) or radiant warmer (n = 26). Vitals were recorded at designated time intervals to assess tolerance of postnatal transitioning. We found no significant difference in the number of SSC interruptions, pulse oximeter readings, initial glucose level, and rates of hypoglycemia, hypothermia, or NICU admission between the two groups.

CONCLUSIONS

Vigorous late preterm neonates transitioned to immediate SSC without additional risks compared to control counterparts. Large, multicenter, and randomized-control studies need to be conducted to establish standardized guidelines for this practice.

Use of acidified versus non-acidified liquid human milk fortifier in very low birth weight infants: A retrospective comparison of clinical outcomes

BACKGROUND

Use of human milk is recommended for low birth weight (VLBW) infants, but must be safety fortified with sterile liquid fortifiers to be nutritionally sufficient. Due to clinical concern for a high incidence of metabolic acidosis among VLBW infants fed human milk fortified with acidified liquid human milk fortifier (ALHMF), we aimed to retrospectively compare the outcomes of infants fed ALHMF to those fortified with non-acidified liquid HMF (NLHMF).

METHODS

Medical records of VLBW neonates admitted to our institution's neonatal intensive care unit from July 1st, 2013 to June 30th, 2014 were reviewed. 129 patients were included in the study, 61 of which received ALHMF and 68 received NLHMF. Metabolic, nutritional and clinical outcomes, including growth, were compared between the two cohorts.

RESULTS

Of the infants who received ALHMF, 70.5% developed metabolic acidosis compared to only 11.8% in the NLHMF group (p < 0.001). In addition, infants who received NLHMF had a 10% greater growth velocity during the period of fortification (p = 0.01). During the full course of hospitalization, no difference in growth velocity was seen between the groups and greater length gains were found in the ALHMF group.

CONCLUSIONS

The use of human milk fortified with ALHMF was associated with an increased incidence of metabolic acidosis and poorer growth during the period of fortification when compared to NLHMF-fortified feedings. These growth effects were not apparent when the duration of hospitalization was considered, suggesting a need for further study to better characterize the advantages and disadvantages of each fortifier.

Sexual dimorphism in developmental and diet-dependent circulating retinol binding protein 4

OBJECTIVE

Retinol binding protein 4 (RBP4) transports vitamin A (Retinol) in the blood and contributes mechanistically to the linkage between obesity, insulin resistance and associated comorbidities including type 2 diabetes mellitus, coronary artery and neoplastic diseases. Circulating RBP4 levels have variably been associated with body mass and gender differences. Many of these differences have been demonstrated after limited dietary interventions, and/or at single unique time points. This study investigated the impact of sex and age as biologic variables as well as high versus low fat diets on development of obesity, RBP4 levels and insulin resistance in C57BL/6J mice.

METHODS

Male and female C57BL/6J mice were fed for 400 days with either low or high fat diets. Female mice were also evaluated on same diets after ovariectomy or sham ovariectomy. Mice were monitored for changes in weight, circulating levels RBP4, glucose and insulin at 100-day intervals and also by 2-hour glucose tolerance tests.

RESULTS

All mice on low or high fat diets gained weight. Mice on high fat diets showed significantly greater weight gain than those on low fat. Male mice showed significantly greater weight gain compared with females on corresponding diet. Male mice compared with females already showed significantly higher RBP4 levels even before starting diets. Sex differences were maintained for more than 1 year. Gender differences in RBP4 were associated with significant differences in development of glucose intolerance and insulin resistance.

CONCLUSIONS

Male compared with female C57BL/6J mice show significant gender differences in circulating RBP4 levels from 6 weeks of age, extending more than 1 year. Gender differences in RBP4 may be mechanistically associated with protection against glucose intolerance and insulin resistance. Targeting RBP4 pathways could be useful to disrupt gender differences in insulin resistance and disparities in comorbidities.

Chondrocyte expansion is associated with loss of primary cilia and disrupted hedgehog signalling

Tissue engineering-based therapies targeting cartilage diseases, such as osteoarthritis, require in vitro expansion of articular chondrocytes. A major obstacle for these therapies is the dedifferentiation and loss of phenotype accompanying chondrocyte expansion. Recent studies suggest that manipulation of hedgehog signalling may be used to promote chondrocyte re-differentiation. Hedgehog signalling requires the primary cilium, a microtubule-based signalling compartment, the integrity of which is linked to the cytoskeleton. We tested the hypothesis that alterations in cilia expression occurred as consequence of chondrocyte dedifferentiation and influenced hedgehog responsiveness. In vitro chondrocyte expansion to passage 5 (P5) was associated with increased actin stress fibre formation, dedifferentiation and progressive loss of primary cilia, compared to primary (P0) cells. P5 chondrocytes exhibited ~50 % fewer cilia with a reduced mean length. Cilia loss was associated with disruption of ligand-induced hedgehog signalling, such that P5 chondrocytes did not significantly regulate the expression of hedgehog target genes (GLI1 and PTCH1). This phenomenon could be recapitulated by applying 24 h cyclic tensile strain, which reduced cilia prevalence and length in P0 cells. LiCl treatment rescued cilia loss in P5 cells, partially restoring hedgehog signalling, so that GLI1 expression was significantly increased by Indian hedgehog. This study demonstrated that monolayer expansion disrupted primary cilia structure and hedgehog signalling associated with chondrocyte dedifferentiation. This excluded the possibility to use hedgehog ligands to stimulate re-differentiation without first restoring cilia expression. Furthermore, primary cilia loss during chondrocyte expansion would likely impact other cilia pathways important for cartilage health and tissue engineering, including transforming growth factor (TGF), Wnt and mechanosignalling.

Differential cerebellar GABAA receptor expression in mice with mutations in CaV2.1 (P/Q-type) calcium channels

Ataxia is the predominant clinical manifestation of cerebellar dysfunction. Mutations in the human CACNA1A gene, encoding the pore-forming α1 subunit of CaV2.1 (P/Q-type) calcium channels, underlie several neurological disorders, including Episodic Ataxia type 2 and Familial Hemiplegic Migraine type 1 (FHM1). Several mouse mutants exist that harbor mutations in the orthologous Cacna1a gene. The spontaneous Cacna1a mutants Rolling Nagoya (tg(rol)), Tottering (tg) and Leaner (tg(ln)) mice exhibit behavioral motor phenotypes, including ataxia. Transgenic knock-in (KI) mouse strains with the human FHM1 R192Q and S218L missense mutations have been generated. R192Q KI mice are non-ataxic, whereas S218L KI mice display a complex behavioral phenotype that includes cerebellar ataxia. Given the dependence of γ-aminobutyric acid type A (GABAA) receptor subunit functioning on localized calcium currents, and the functional link between GABAergic inhibition and ataxia, we hypothesized that cerebellar GABAA receptor expression is differentially affected in Cacna1a mutants and contributes to the ataxic phenotype. Herein we quantified functional GABAA receptors and pharmacologically dissociated cerebellar GABAA receptors in several Cacna1a mutants. We did not identify differences in the expression of GABAA receptor subunits or in the number of functional GABAA receptors in the non-ataxic R192Q KI strain. In contrast, tg(rol) mice had a ∼15% decrease in the number of functional GABAA receptors, whereas S218L KI mice showed a ∼29% increase. Our data suggest that differential changes in cerebellar GABAA receptor expression profile may contribute to the neurological phenotype of cerebellar ataxia and that targeting GABAA receptors might represent a feasible complementary strategy to treat cerebellar ataxia.

Optical Limiting in a Photorefractive Polymer

Optical limiting has been suggested as a possible device application of high gain photorefractive (PR) polymers. The principle of operation relies on the existence of amplified scattering (beam fanning) to deplete the intensity of the incident coherent optical beam. The newest photorefractive polymers show a combination of high gain and reasonable speed, and we show how these materials behave as a beam fanning optical limiter and as a limiter based on self-pumped phase conjugation. A prototype cascaded beam fanning device is demonstrated and its salient features are discussed.

A student authored online medical education textbook: editing patterns and content evaluation of a medical student wiki

The University of Minnesota medical student wiki (UMMedWiki) allows students to collaboratively edit classroom notes to support medical education. Since 2007, UMMedWiki has grown to include 1,591 articles that have collectively received 1.2 million pageviews. Although small-scale wikis have become increasingly important, little is known about their dynamics compared to large wikis, such as Wikipedia. To better understand UMMedWiki's management and its potential reproducibility at other medical schools, we used an edit log with 28,000 entries to evaluate the behavior of its student editors. The development of tools to survey UMMedwiki allows for quality comparisons that improve both the wiki and the curriculum itself. We completed a content survey by comparing the UMMedWiki with two types of rubric data: TIME, a medical education taxonomy consisting of 1500 terms and national epidemiological data on 2,100 diseases.

The influence of experimental manipulations on chewing speed during in vivo laboratory research in tufted capuchins (Cebus apella)

Even though in vivo studies of mastication in living primates are often used to test functional and adaptive hypotheses explaining primate masticatory behavior, we currently have little data addressing how experimental procedures performed in the laboratory influence mastication. The obvious logistical issue in assessing how animal manipulation impacts feeding physiology reflects the difficulty in quantifying mechanical parameters without handling the animal. In this study, we measured chewing cycle duration as a mechanical variable that can be collected remotely to: 1) assess how experimental manipulations affect chewing speed in Cebus apella, 2) compare captive chewing cycle durations to that of wild conspecifics, and 3) document sources of variation (beyond experimental manipulation) impacting captive chewing cycle durations. We find that experimental manipulations do increase chewing cycle durations in C. apella by as much as 152 milliseconds (ms) on average. These slower chewing speeds are mainly an effect of anesthesia (and/or restraint), rather than electrode implantation or more invasive surgical procedures. Comparison of captive and wild C. apella suggest there is no novel effect of captivity on chewing speed, although this cannot unequivocally demonstrate that masticatory mechanics are similar in captive and wild individuals. Furthermore, we document significant differences in cycle durations due to inter-individual variation and food type, although duration did not always significantly correlate with mechanical properties of foods. We advocate that the significant reduction in chewing speed be considered as an appropriate qualification when applying the results of laboratory-based feeding studies to adaptive explanations of primate feeding behaviors.

Observations of hand preference in wild groups of white-faced sakis (Pithecia pithecia) in Suriname

Hand preference is well observed in humans and some primates. Unlike many other primates, however, humans show a consistent hand preference across a variety of tasks, and a distinct right-handed skew at the population level. Although there are a moderate number of published studies, primate hand preference literature is unbalanced by the large number of studies on only a few species. No previous studies have addressed hand preference in white-faced sakis (WFS; Pithecia pithecia). We followed three habituated groups of wild WFS in Suriname and recorded individual hand preference for six different manual behaviors. There was no consistent hand preference across a range of uni-manual behaviors for any individual. Likewise, there were significantly more ambidextrous individuals in the population than expected (χ(2) (df = 2) = 11.2, P = 0.004) and thus, no population level hand preference. Our findings contribute baseline data to the debate of primate hand lateralization, and support the notion that lateralization of hand function does not characterize all species.

Response of AIDS-related plasmablastic lymphoma (PBL) to bortezomib

e19562

PBL are a group of highly aggressive neoplasms originally described in the oral cavity and jaws of HIV-infected patients. An AIDS-defining illness, PBL comprises 2.6% of AIDS-related lymphomas. PBL are best distinguished by their unique immunophenotype. They are terminally differentiated B-cell neoplasms, and typically lack common B-cell markers but uniformly express plasma cell markers. We report the first case of PBL that responded to bortezomib. A 42-year-old male with newly diagnosed AIDS presented with nausea, vomiting, bloody diarrhea and epigastric pain. EGD with biopsy revealed a high-grade PBL of the stomach. Flow cytometry was negative for CD45 and all common epithelial, T-cell and B-cell markers, but was positive for CD138 and p63(VS38c). Karyotyping revealed t(8;14), amongst other abnormalities. PET/CT showed significant hypermetabolism in multiple thoracic and abdominal lymph nodes, the left lung, liver and several bones. The diagnosis was stage IVBE PBL. Highly active anti-retroviral therapy was begun. Anthracycline-based chemotherapy was avoided due to persistent hyperbilirubinemia. Bortezomib was then administered at a dose of 1.3 mg/m2 IV on days 1, 4, 8 and 11. PET/CT on day 7 showed a marked decrease in hypermetabolism after only 2 doses, signifying a dramatic treatment response. After a total of 4 doses of bortezomib, he unfortunately succumbed to severe septic shock before a repeat PET/CT could be obtained. The prognosis of PBL is poor, with a median survival of about 6 months in most series. The WHO classifies PBL as a variant of diffuse large B-cell lymphoma. Accordingly, CHOP and CHOP-like regimens have mostly been used. However, studies of their immunophenotype and molecular histogenesis suggest that PBL are more closely related to plasma cell neoplasms. Bortezomib is a proteasome inhibitor widely used in multiple myeloma and mantle cell lymphoma. We chose bortezomib based on our patient's poor performance status and immune function, the desire to avoid combination chemotherapy, and translocations involving the immunoglobulin heavy chain gene locus (8;14) similar to those seen in multiple myeloma(4;14, 14;16) and mantle cell lymphoma(11;14). A shift in the paradigm of treatment of PBL towards agents effective in plasma cell malignancies may be necessary.

[Table: see text]

Aberrant cerebellar granule cell-specific GABAA receptor expression in the epileptic and ataxic mouse mutant, Tottering

The Tottering (cacna1a(tg)) mouse arose as a consequence of a spontaneous mutation in cacna1a, the gene encoding the pore-forming subunit of the pre-synaptic P/Q-type voltage-gated calcium channel (VGCC, Ca(V)2.1). The mouse phenotype includes ataxia and intermittent myoclonic seizures which have been attributed to impaired excitatory neurotransmission at cerebellar granule cell (CGC) parallel fiber-Purkinje cell (PF-PC) synapses [Zhou YD, Turner TJ, Dunlap K (2003) Enhanced G-protein-dependent modulation of excitatory synaptic transmission in the cerebellum of the Ca(2+)-channel mutant mouse, tottering. J Physiol 547:497-507]. We hypothesized that the expression of cerebellar GABA(A) receptors may be affected by the mutation. Indeed, abnormal GABA(A) receptor function and expression in the cacna1a(tg) forebrain has been reported previously [Tehrani MH, Barnes EM Jr (1995) Reduced function of gamma-aminobutyric acid A receptors in tottering mouse brain: role of cAMP-dependent protein kinase. Epilepsy Res 22:13-21; Tehrani MH, Baumgartner BJ, Liu SC, Barnes EM Jr (1997) Aberrant expression of GABA(A) receptor subunits in the tottering mouse: an animal model for absence seizures. Epilepsy Res 28:213-223]. Here we show a deficit of 40.2+/-3.6% in the total number of cerebellar GABA(A) receptors expressed (gamma2+delta subtypes) in adult cacna1a(tg) relative to controls. [(3)H]Muscimol autoradiography identified that this was partly due to a significant loss of CGC-specific alpha6 subunit-containing GABA(A) receptor subtypes. A large proportion of this loss of alpha6 receptors was attributable to a significantly reduced expression of the CGC-specific benzodiazepine-insensitive Ro15-4513 (BZ-IS) binding subtype, alpha6betagamma2 subunit-containing receptors. BZ-IS binding was reduced by 36.6+/-2.6% relative to controls in cerebellar membrane homogenates and by 37.2+/-3.7% in cerebellar sections. Quantitative immunoblotting revealed that the steady-state expression level of alpha6 and gamma2 subunits was selectively reduced relative to controls by 30.2+/-8.2% and 38.8+/-13.1%, respectively, alpha1, beta3 and delta were unaffected. Immunohistochemically probed control and cacna1a(tg) cerebellar sections verified that alpha6 and gamma2 subunit expression was reduced and that this deficit was restricted to the CGC layer. Thus, we have shown that abnormal cerebellar P/Q-type VGCC activity results in a deficit of CGC-specific subtype(s) of GABA(A) receptors which may contribute to, or may be a consequence of the impaired cerebellar network signaling that occurs in cacna1a(tg) mice.

Where and when is blood transfused? An observational study of the timing and location of red cell transfusions in the north of England

BACKGROUND AND OBJECTIVES

This study was undertaken to provide denominator data relating to the timing and location of transfusion, to support interpretation of reports of incorrect blood component transfused (IBCT) events to the UK Serious Hazards of Transfusion (SHOT) scheme.

MATERIALS AND METHODS

The study was carried out in 29 hospitals in northern England. Data on the timing, location and specialty responsible for transfusion were collected retrospectively (usually the following day) for all red cell units transfused over a 7-day period in September 2005. The timing and location of transfusion of these units was compared with those IBCT reports to SHOT between 1 January and 31 December 2005 in which there was an error in blood collection from the hospital storage site and/or administration to the patient.

RESULTS

Data were received on 3123 red cell units, 3118 of which were analysable. Individual hospitals returned data on between 1 and 279 units. The data showed that 888 out of 3118 (28.5%) of units were transfused between 20:00 and 08:00 hours, while 63 out of 169 (37%) of IBCT reports to SHOT where there was an error in blood collection/administration were recorded as occurring during this time period.

CONCLUSIONS

Comparison of our data with those from SHOT suggests that transfusions that are given outside core hours are more likely to be associated with clinical errors.

The prevalence of nocturia and its effect on health-related quality of life and sleep in a community sample in the USA

OBJECTIVE

To evaluate the prevalence of nocturia and its effects, with and without concomitant overactive bladder (OAB, i.e. urgency, frequency, urge incontinence and nocturia), on health-related quality of life (HRQoL) and sleep.

SUBJECTS AND METHODS

A national survey was conducted in the USA to assess the prevalence of OAB and nocturia. A nested case-control study was conducted among respondents with OAB symptoms and age- and gender-matched controls, with participants completing a series of questionnaires on HRQoL (OAB-q, Short Form-36, and Medical Outcomes Study (MOS) sleep scale). Descriptive analyses, t-tests, analysis of variance with post hoc comparisons and multivariate regressions were used to analyse the data.

RESULTS

In all, 5204 people participated in the survey, with 919 in the nested case-control study. The sample population had a mean age of 45.8 years, was 52.6% female and 80% Caucasian. In the community sample, 31% reported > 1 void/night and 14.2% reported > 2 voids/night. The prevalence of nocturia increased with age, with no gender differences. For OAB cases, 66.8% reported > 1 void/night and 42.2% reported > 2. In the case-control cohort there were significant HRQoL differences (P < 0.01), with increasing episodes of nocturia in all OAB-q subscales except social interaction. The amount of sleep per night was significantly correlated with the sleep, concern and social interaction OABq subscale scores. The number of nocturia episodes/night was also significantly (P = 0.02) associated with the number of hours of sleep/night.

CONCLUSION

Nocturia is widely prevalent and increases with age, affecting men and women equally. Incremental increases in the number of voids/night have further negative effects on sleep, symptom bother, and HRQoL.

Neuronal activity and its influence on developmentally regulated GABA(A) receptor expression in cultured mouse cerebellar granule cells

Mouse cerebellar granule cells (CGCs) were cultured in either non-depolarising (5 mM KCl, '5K') or depolarising (25 mM KCl, '25K') media. CGCs at 5K developed an elaborate network of processes and formed compact cell aggregates, whilst at 25K, cell aggregation was rarely observed. GABA(A) receptor (GABAR) expression was significantly affected by the culture conditions. Depolarisation resulted in a approximately 55% reduction in the expression of total specific [(3)H]Ro15-4513 binding sites, largely due to a >85% loss of the flunitrazepam-insensitive (BZ-IS) subtype of binding sites. The number of flunitrazepam-sensitive (BZ-S) [(3)H]Ro15-4513 binding sites expressed and the K(D) of [(3)H]Ro15-4513 to either GABAR subtype were not significantly affected. The BZ-S subtype expressed by 5K CGCs was essentially all type I, as expected of mature CGCs, however at 25K, these were predominantly type II (approximately 70%) and zolpidem-insensitive (approximately 30%)-pharmacological finger-prints of immature CGCs. By immunoblotting we determined that CGCs cultured at 25K expressed GABAR alpha1, alpha6 and beta3 subunits at 14, 3 and 167% of 5K levels, respectively. GABAR beta2 subunits, however, were barely detectable. The changes in GABAR subunit expression were paralleled by similar changes in the steady-state levels of the subunit mRNAs. The switch from type I to type II BZ-S pharmacology upon depolarisation was mirrored by a switch in gene expression from alpha1 (12% of 5K) to alpha3 (371% of 5K). Interestingly, although depolarisation reduced beta2 subunit mRNA to 25% of 5K, beta2 protein was undetectable.Thus, we have shown that electrically active (5K) mouse CGCs differentiate in vitro to express a GABAR profile expected of adult CGCs in vivo. Chronically depolarised, electrically silent CGCs appear to be developmentally arrested, expressing some GABAR characteristics of prenatal CGCs. This model system should prove invaluable for elucidating signalling pathways orchestrating GABAR differentiation.

Translating research into practice. Implications of the Thunder Project II

The Thunder Project II study described procedural pain in a variety of acute and critical care settings. The procedures studied were turning, tracheal suctioning, wound drain removal, nonburn wound dressing change, femoral sheath removal, and central venous catheter insertion. Turning had the highest mean pain intensity, whereas femoral sheath removal and central venous catheter insertion had the least pain intensity in adults. Nonwound dressing change had the highest pain intensity for teenagers. Pain occurred in procedures that are often repeated several times a day as well as in those that may be single events. There is a wide range of pain responses to any of these procedures; as a result, standardized and thoughtful pain, and distress assessments are warranted. Planning of care, including the use of preemptive analgesic interventions, needs to be individualized. Future studies are needed to describe patient responses to other commonly performed nursing procedures and to identify effective interventions for reducing procedural pain and distress.

Preservation of light signaling to the suprachiasmatic nucleus in vitamin A-deficient mice

To investigate the role of retinal-based pigments (opsins) in circadian photoreception in mice, animals mutated in plasma retinol binding protein were placed on a vitamin A-free diet and tested for photic induction of gene expression in the suprachiasmatic nucleus. After 10 months on the vitamin A-free diet, the majority of mice contained no detectable retinal in their eyes. These mice demonstrated fully intact photic signaling to the suprachiasmatic nucleus as measured by acute mPer mRNA induction in the suprachiasmatic nucleus in response to bright or dim light. The data suggest that a non-opsin pigment is the primary circadian photoreceptor in the mouse.

Patients' perceptions and responses to procedural pain: results from Thunder Project II

BACKGROUND

Little is known about the painfulness of procedures commonly performed in acute and critical care settings.

OBJECTIVE

To describe pain associated with turning, wound drain removal, tracheal suctioning, femoral catheter removal, placement of a central venous catheter, and nonburn wound dressing change and frequency of use of analgesics during procedures.

METHODS

A comparative, descriptive design was used. Numeric rating scales were used to measure pain intensity and procedural distress; word lists, to measure pain quality.

RESULTS

Data were obtained from 6201 patients: 176 younger than 18 years and 5957 adults. Mean pain intensity scores for turning and tracheal suctioning were 2.80 and 3.00, respectively (scale, 0-5), for 4- to 7-year-olds and 52.0 and 28.1 (scale, 0-100) for 8- to 12-year-olds. For adolescents, mean pain intensity scores for wound dressing change, turning, tracheal suctioning, and wound drain removal were 5 to 7 (scale, 0-10); mean procedural distress scores were 4.83 to 6.00 (scale, 0-10). In adults, mean pain intensity scores for all procedures were 2.65 to 4.93 (scale, 0-10); mean procedural distress scores were 1.89 to 3.47 (scale, 0-10). The most painful and distressing procedures were turning for adults and wound care for adolescents. Procedural pain was often described as sharp, stinging, stabbing, shooting, and awful. Less than 20% of patients received opiates before procedures.

CONCLUSIONS

Procedural pain varies considerably and is procedure specific. Because procedures are performed so often, more individualized attention to preparation for and control of procedural pain is warranted.

Patients' perceptions and responses to procedural pain: results from Thunder Project II

BACKGROUND: Little is known about the painfulness of procedures commonly performed in acute and critical care settings. OBJECTIVE: To describe pain associated with turning, wound drain removal, tracheal suctioning, femoral catheter removal, placement of a central venous catheter, and nonburn wound dressing change and frequency of use of analgesics during procedures. METHODS: A comparative, descriptive design was used. Numeric rating scales were used to measure pain intensity and procedural distress; word lists, to measure pain quality. RESULTS: Data were obtained from 6201 patients: 176 younger than 18 years and 5957 adults. Mean pain intensity scores for turning and tracheal suctioning were 2.80 and 3.00, respectively (scale, 0-5), for 4- to 7-year-olds and 52.0 and 28.1 (scale, 0-100) for 8- to 12-year-olds. For adolescents, mean pain intensity scores for wound dressing change, turning, tracheal suctioning, and wound drain removal were 5 to 7 (scale, 0-10); mean procedural distress scores were 4.83 to 6.00 (scale, 0-10). In adults, mean pain intensity scores for all procedures were 2.65 to 4.93 (scale, 0-10); mean procedural distress scores were 1.89 to 3.47 (scale, 0-10). The most painful and distressing procedures were turning for adults and wound care for adolescents. Procedural pain was often described as sharp, stinging, stabbing, shooting, and awful. Less than 20% of patients received opiates before procedures. CONCLUSIONS: Procedural pain varies considerably and is procedure specific. Because procedures are performed so often, more individualized attention to preparation for and control of procedural pain is warranted.

Immunological identification of the mammalian H3 histamine receptor in the mouse brain

Affinity-purified antibodies raised against the peptide sequence H3 (349-358) receptor specifically recognized two protein species with Mr 62,000 and 93,000 in adult mouse forebrain membranes. Both immunoreactive species were suppressed greatly by preincubation of the antibody with the respective peptide. Immunohistochemical analysis using affinity-purified anti-H3 (349-358) antibodies yielded a high degree of coincidence with ligand-autoradiographical information, with high levels detected in the CA3 and dentate gyrus of the hippocampus, laminae V of the cerebral cortex, the olfactory tubercle, Purkinje cell layer of the cerebellum, substantia nigra, globus pallidus, thalamus and striatum. This study suggests further biochemical evidence for multiple H3 receptor subtypes and the widespread distribution of the H3 receptor in the mammalian brain.

Hemoglobin adducts from acrylonitrile and ethylene oxide in cigarette smokers: effects of glutathione S-transferase T1-null and M1-null genotypes

Acrylonitrile (ACN) is used to manufacture plastics and fibers. It is carcinogenic in rats and is found in cigarette smoke. Ethylene oxide (EO) is a metabolite of ethylene, also found in cigarette smoke, and is carcinogenic in rodents. Both ACN and EO undergo conjugation with glutathione. The objectives of this study were to examine the relationship between cigarette smoking and hemoglobin adducts derived from ACN and EO and to investigate whether null genotypes for glutathione transferase (GSTM1 and GSTT1) alter the internal dose of these agents. The hemoglobin adducts N-(2-cyanoethyl)valine (CEVal), which is formed from ACN, and N-(2-hydroxyethyl)valine (HEVal), which is formed from EO, and GST genotypes were determined in blood samples obtained from 16 nonsmokers and 32 smokers (one to two packs/day). Smoking information was obtained by questionnaire, and plasma cotinine levels were determined by immunoassay. Glutathione transferase null genotypes (GSTM1 and GSTT1) were determined by PCR. Both CEVal and HEVal levels increased with increased cigarette smoking dose (both self-reported and cotinine-based). CEVal and HEVal levels were also correlated. GSTM1 and GSTT1 genotypes had little effect on CEVal concentrations. GSTM1 null genotypes had no significant impact on HEVal. However, HEVal levels were significantly elevated in GSTT1-null individuals when normalized to smoking status or cotinine levels. The ratio of HEVal:CEVal was also elevated in GSTT1-null smokers (1.50 +/- 0.57 versus 0.88 +/- 0.24; P = 0.0002). The lack of a functional GSTT1 is estimated to increase the internal dose of EO derived from cigarette smoke by 50-70%.

Immunohistochemical localization of N-methyl-D-aspartate receptor NR1, NR2A, NR2B and NR2C/D subunits in the adult mammalian cerebellum

The distributions of the N-methyl-D-aspartate (NMDA) receptor NR1, NR2A, NR2B and NR2C/D subunits were mapped in adult mouse cerebellum using subunit-specific antibodies. Immunostaining with anti-NR1 antibodies was prominent in cell bodies and dendritic arbors of Purkinje cells, was light to moderate in cerebellar granule cells, Golgi interneurons and interneurons in the molecular layer. Anti-NR2A subunit-specific antibody staining of mouse cerebellum was moderate in the granule cells, and moderate to dense in Purkinje neurons and Bergmann glia. However, Purkinje neurons were not immunolabelled in adult rat brain. Anti-NR2B subunit-specific immunostaining was prominent in Purkinje cell bodies and dendrites but absent from the granule cell layer. Anti-NR2C/D subunit-specific immunostaining was largely restricted to cerebellar granule cells. These studies reveal that NMDA receptor subunits display distinct but overlapping expression patterns in the adult mammalian cerebellum. Furthermore, we have observed some differences between rats and mice in terms of the NMDA receptor subunits expressed in specific cerebellar cell types.

Cyclic AMP-mediated regulation of GABA(A) receptor subunit expression in mature rat cerebellar granule cells: evidence for transcriptional and translational control

Exposure of rat cerebellar granule cells cultured to maturity in vitro to forskolin, N6,2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (Bt2cAMP), and 3-isobutyl-1-methylxanthine (IBMX) down-regulated GABA(A) receptor alpha6 and beta3 subunits but up-regulated alpha1 and beta2 subunits with respect to vehicle-treated controls. Dideoxyforskolin had no effect on subunit expression. Protein kinase A inhibitors, H-89 and Rp-adenosine 3',5'cyclic monophosphothioate, prevented these effects on alpha1 but not alpha6 subunit expression. Flunitrazepam-sensitive [3H]Ro 15-4513 binding sites were increased by 144 +/- 20% following forskolin treatment. [3H]Ro 15-4513 photoaffinity labelling showed that the GABA(A) receptor alpha1 subunit was the principal locus of the increased flunitrazepam-sensitive [3H]Ro 15-4513 binding. Forskolin decreased flunitrazepam-insensitive [3H]Ro 15-4513 binding sites by 25 +/- 8% and resulted in a 20% decrease in the irreversible incorporation of radioactivity in the alpha6 subunit. Steady-state levels of GABA(A) receptor subunit mRNAs were determined by semiquantitative RT-PCR in forskolin-treated cultures. Forskolin, Bt2cAMP, and IBMX down-regulated GABA(A) receptor alpha6 subunit mRNA expression; alpha1 and beta3 mRNA levels were unaffected, whereas beta2 subunit mRNA was up-regulated. Dideoxyforskolin had no significant effect on alpha1, alpha6, beta2, and beta3 mRNA levels. Thus, in mature cerebellar granule cells, GABA(A) receptor expression can be regulated by intracellular cyclic AMP levels. This occurs at the level of gene transcription and/or translation by mechanisms that are only partially governed by protein kinase A.

XRCC1 polymorphisms: effects on aflatoxin B1-DNA adducts and glycophorin A variant frequency

Hereditary genetic defects in DNA repair lead to increased risk of cancer. Polymorphisms in several DNA repair genes have been identified; however, the impact on repair phenotype has not been elucidated. We explored the relationship between polymorphisms in the DNA repair enzyme, XRCC1 (codons 194, 280, and 399), and genotoxic end points measured in two populations: (a) placental aflatoxin B1 DNA (AFB1-DNA) adducts in a group of Taiwanese maternity subjects (n = 120); and (b) somatic glycophorin A (GPA) variants in erythrocytes from a group of North Carolina smokers and nonsmokers (n = 59). AFB1-DNA adducts were measured by ELISA, and erythrocyte GPA variant frequency (NN and NO) was assessed in MN heterozygotes with a flow cytometric assay. XRCC1 genotypes were identified by PCR-RFLPs. The XRCC1 399Gln allele was significantly associated with higher levels of both AFB1-DNA adducts and GPA NN mutations. Individuals with the 399Gln allele were at risk for detectable adducts (odds ratio, 2.4; 95% confidence interval, 1.1-5.4; P = 0.03). GPA NN variant frequency was significantly higher in 399Gln homozygotes (19.6 x 10(-6)) than in Gln/Arg heterozygotes (11.4 x 10(-6); P < 0.05) or Arg/Arg homozygotes (10.1 x 10(-6); P = 0.01). No significant effects were observed for other XRCC1 polymorphisms. These results suggest that the Arg399Gln amino acid change may alter the phenotype of the XRCC1 protein, resulting in deficient DNA repair.

Peer reviewed: creating multidisciplinary research opportunities

A unifying framework model helps researchers to address the complexities of environmental problems.

Relationship of auditory middle latency response and stem-word completion test as indicators of implicit memory formation during general anesthesia

Anesthesia providers are unable to objectively evaluate the amnesic status of an anesthetized patient. One purpose of the study was to evaluate the anesthetized patient's ability to process auditory information while receiving an inhalational or intravenous anesthetic regimen. The other purpose was to examine the relationship of the Pa latency of the auditory middle latency response (AMLR) with the stem-word completion test as an intraoperative indicator of implicit memory formation during general anesthesia. One hundred one adults were randomly assigned in a single-blinded design to either a midazolam or sevoflurane anesthetic regimen. Midazolam was administered at 0.540 microgram/kg per minute with fentanyl and 50% nitrous oxide. The other anesthetic regimen was 1.4% end-tidal concentration of sevoflurane with fentanyl and 50% nitrous oxide. A list of 10 words was repeated 16 times. AMLRs were recorded intraoperatively. The difference between the midazolam groups borderlined statistical significance (P = .07) in illustrating that one may potentially process auditory information while anesthetized. Dissimilar findings were found between the sevoflurane groups (P = .77). An inverse correlation was demonstrated between the midazolam group and Pa latency of the AMLR (r = -0.40, P = .047). Multiple regression of the midazolam group demonstrated that the employment status (r2 = .297, P = .005) and the Pa latency (r2 = .238, P = .003) were the best predictors of the postoperative stem-word completion test (F = 12.61, P = .001). In contrast, no correlation was noted in the sevoflurane group (r = 0.43, P = .07). Thus, the continued evaluation of the AMLR as an intraoperative indicator of implicit memory formation is warranted. With the establishment of the AMLR as an indicator of implicit memory formation during general anesthesia, anesthesia providers could then address the occurrences of traumatic neurosis in the postoperative surgical patient and strive to avoid the medicolegal concerns that may face the healthcare team.

Decreased expression of GABAA receptor alpha6 and beta3 subunits in stargazer mutant mice: a possible role for brain-derived neurotrophic factor in the regulation of cerebellar GABAA receptor expression?

The cerebellar granule cells of the spontaneous recessive mutant mouse strain, stargazer (stg/stg), fail to express brain-derived neurotrophic factor mRNA. This deficit is exclusive to these neurons and is believed to underlie the motor irregularities displayed by stg/stg, though the molecular basis for their phenotype has still to be resolved. Brain-derived neurotrophic factor has been shown to play a role in the postnatal maturation of cerebellar granule cells. Differentiation of these neurons, postnatally, is characterised by a switch in their GABAA receptor subunit expression profile. Notably, the GABAA receptor alpha6 subunit, which is specific to these neurons, becomes detectable at postnatal days 10-14 (P10-14). To determine whether cerebellar GABAA receptor expression has been compromised in stg/stg mice, the expression levels of GABAA receptor alpha1, alpha6, beta2 and beta3 subunits were compared between stg/stg mice and the appropriate wild-type background strain, C57BL/6J (+/+). By quantitative immunoblotting, it was found that the expression of the alpha6 and beta3 subunits was 23+/-8% and 38+/-12% (mean+/-S.E.M., n=6) of control (+/+) levels, respectively. In contrast, the expression of the alpha1 and beta2 subunits was not significantly different from controls, being 116+/-11% and 87+/-24% (mean+/-S.E.M., n=6) of +/+ levels, respectively. Total specific [3H]Ro15-4513 binding activity detected in cerebellar membranes prepared from stg/stg was not significantly different from +/+ mice. However, the benzodiazepine agonist-insensitive subtype of [3H]Ro15-4513 binding activity, a pharmacological motif of alpha6 subunit-containing GABAA receptors, was lower in stg/stg mice relative to the +/+ strain which correlated with the lowered level of alpha6 subunit expression. Thus, we have identified an abnormality in the GABAA receptor profile of stg/stg mutant mice that might underpin its irregular phenotype.

Rural junior high school students' risk factors for and perceptions of teen-age parenthood

A sample consisting of 689 junior high school rural adolescents was surveyed about their perceptions of being a teen parent and their current sexual behavior. A risk factor analysis also was conducted to determine factors that significantly predict whether adolescents had engaged in sexual intercourse. Results indicate that one in nine adolescents had engaged in sexual intercourse (11%). The risk factor analyses showed that smoking and efficacy expectations of not engaging in sexual intercourse were significant predictors for both genders. For the most part, adolescents responded positively on four constructs: 1) attitudes toward being a teen parent; 2) efficacy expectations of not engaging in sexual intercourse; 3) benefits of being a teen parent; and 4) and barriers to being a teen parent. However, when analyses were conducted for males and females separately, females scored higher on each factor. Overall, results indicate these teens recognized problems that may occur from being a teen parent.

The application of a modified proportional-derivative control algorithm to arterial pressure alarms in anesthesiology

OBJECTIVE

We have developed an arterial pressure alarm system based on a modified proportional-derivative (PD) controller algorithm, and prospectively tested its ability to predict significant hypotensive episodes, defined as systolic arterial pressure < 80 mmHg, in comparison to conventional limit alarms.

METHODS

The alarm algorithm was tuned to detect hypotension using selected invasive arterial pressure traces taken from ten patients who had large intra-operative arterial pressure changes. The algorithm's performance was then tested prospectively in comparison to conventional limit alarms and median filtered limit alarms, set at 85 mmHg and 90 mmHg, for its ability to predict hypotensive episodes in a further 100 patients who required invasive arterial pressure monitoring.

RESULTS

For the PD alarm algorithm, onset times for significant hypotensive episodes were between those of limit alarms set at 85 mmHg and 90 mmHg. Offset times were similar to the 85 mmHg limit alarms. The false positive rate was 34% compared with 45-64% for the other alarms (p < 0.01). Using our definitions, there was one false negative in the PD group, being a 15 second drop in observed arterial pressure, when a non invasive blood pressure cuff was inflated above the arterial line.

CONCLUSIONS

An arterial pressure alarm system design based on a closed loop control algorithm offered improved perform ance over conventional limit alarms and in addition provided a graded output of severity of the hypotension.

PHOTOREFRACTIVE POLYMERS

▪ Abstract  Rapid advances in the field of photorefractive polymers and composites have in the brief time since their inception in 1991 led to the development of high-performance materials with refractive index modulations approaching 0.01, dif-fraction efficiencies close to 100%, and net two-beam coupling gain coefficients exceeding 200 cm−1 in samples typically 100 μm thick. This paper reviews the current state of research, from the most successful synthetic strategies to produce polymeric photorefractive materials, to their emerging uses in applications. Two-beam coupling and four-wave mixing measurement techniques are presented and their importance in the characterization of the photorefractive properties of new materials is explained. The physics of the photorefractive effect in polymers is discussed with emphasis placed on the differences compared with the traditional inorganic photorefractive crystals. In particular, the orientational enhancement mechanism, which is believed to be responsible for the high performance of most of the low-glass-transition-temperature systems, is discussed in detail.

Measurement of the spatial phase shift in high-gain photorefractive materials

The correct determination of the spatial phase shift ø(p) in photorefractive materials is crucial to the proper characterization of novel materials. It is shown that the grating translation techniques commonly used for the measurement of ø(p) need to be reevaluated for high-gain materials. Strong energy and phase coupling leads to nonuniform slanted gratings, which result in an apparent dependence of the phase shift of the beam ratio and the optical polarization. A revised theory is presented, and analytical solutions are obtained for the special case of ø(p)?pi/2 . Numerical solutions for arbitrary ø(p) are in good agreement with measurements in a photorefractive polymer.

Spectrum of somatic mutation at the hypoxanthine phosphoribosyltransferase (hprt) gene of healthy people

Understanding the significance of somatic mutations requires knowledge of the mutations that occur in vivo in healthy people. The molecular characterization of mutations in the hypoxanthine phosphoribosyltransferase (hprt) gene in 217 independent T-lymphocyte mutants from 172 donors, including smoking and non-smoking males and females, reveals a broad spectrum of in vivo somatic mutation occurring in a population of healthy people. Identification of the DNA alteration in individual mutant clones was accomplished using either one or a combination of multiplex polymerase chain reaction analysis of genomic DNA, sequencing of cDNA, and genomic DNA sequencing. The total spectrum consists of 59% (128/217) base substitutions: 126 simple and two tandem CC>TT base substitutions; 39% (85/217) deletion/insertion type mutations: 30 frameshifts, 26 small (3-200 basepairs) and 27 large deletions, and two duplications; and the remaining 2% (4/217) complex mutations involving the deletion of one to 11 basepairs which are replaced by 1 to 10 basepairs. No significant difference was detected between the base substitution spectra for the smokers and the non-smokers. Analysis of the number of mutations occurring at any one base position led to the identification of three hotspots for mutations at basepairs 197, 508 and 617, in the hprt gene coding region. Spontaneous deamination of CpG may be implicated in the creation of basepair 508 as a hotspot since all mutations detected are C>T transitions resulting in the nonsense mutation, TAG. At basepairs 197 and 617 both G>T transversions and G>A transitions were found indicating that at least two mechanisms were involved in creating mutations at these positions. Comparison of the mutation spectra from two populations can provide insight into the origin of the mutations. This study provides an excellent base for comparison of mutation spectra in other human populations.

Bidirectional regulation of GABAA receptor alpha1 and alpha6 subunit expression by a cyclic AMP-mediated signalling mechanism in cerebellar granule cells in primary culture

Forskolin treatment of cerebellar granule cells in culture resulted in bidirectional regulation of the expression of GABAA receptor alpha1 and alpha6 subunits. Thus, forskolin applied at 2 days in vitro (DIV) increased expression of the alpha1 subunit but decreased the expression of the alpha6 subunit. Values with respect to control cultures, both assayed at 9 DIV by immunoblotting, were 310 +/- 48% for alpha1 and 25 +/- 16% for the alpha6 subunit. Similar effects were evoked following chronic treatment with both dibutyryl cyclic AMP and 3-isobutyl-1-methylxanthine. Dideoxyforskolin had no effect on the level of expression of either the alpha1 or the alpha6 GABAA receptor subunits. The changes in subunit expression were accompanied by a 1.7-fold increase in number of total specific [3H]Ro 15-4513 binding sites expressed by intact cerebellar granule cells. This increase in total binding sites was accommodated by a 2.7-fold increase in number of diazepam-sensitive Ro 15-4513 binding sites in accordance with the observed increase in alpha1 subunit expression. The number of diazepam-insensitive subtype of binding sites were not significantly changed. These results suggest that GABAA receptor subtype expression can be differentially regulated by intracellular cyclic AMP concentration.

Developmental regulation of expression of GABAA receptor alpha 1 and alpha 6 subunits in cultured rat cerebellar granule cells

We have studied the postnatal development of GABAA receptor alpha 1 and alpha 6 subunits expressed by primary cultures of cerebellar granule cells originating from 2-day-old (postnatal day 2, P2) and 10-day-old (P10) rat neonates. At these ages, the granule cells are at distinct stages of cerebellar development. In both cases, GABAA receptor alpha 1 and alpha 6 subunit-like immunoreactivities were detected, and displayed temporal expression profiles that were correlated with the maturity of the cerebella from which the cultured granule cells were derived. Using two different specificity anti-alpha 1 subunit-specific antibodies, immunoreactive species with M(r) 53,000 Da and 54,000 Da were detected by immunoblotting. The lower 53,000-Da band co-migrated with the alpha 1 subunit-like immunoreactivity detected in GABAA receptors purified from adult rat forebrain by benzodiazepine affinity chromatography. This 53,000-Da alpha 1 subunit-like immunoreactive species was detected at day 1 in vitro (1 DIV) in P10 cultures and 3-5 DIV in P2 cultures. The GABAA receptor alpha 6 subunit-like immunoreactivity (58,000 Da) was not detected until 5-7 DIV in P10 and 9-11 DIV in P2-derived cultures. The appearance of alpha 6 subunit-like immunoreactivity was paralleled by an up-regulation of alpha 1 subunit expression and a concomitant increase in diazepam-insensitive (DZ-IS) [3H]Ro 15-4513 binding activity, a pharmacological characteristic of alpha 6 and alpha 1 alpha 6-subunit-containing GABAA receptors (Pollard et al. J. Biol. Chem., 270, 21,285-21,290, (1995)). Antagonism of both non-NMDA and NMDA subtypes of ionotropic glutamate receptors did not significantly affect the developmental profile, the level of GABAA receptor alpha 6 subunit or the total DZ-IS or DZ-S [3H]Ro 15-4513 binding activities expressed by these neurons. These results provide further evidence that the expression of specific GABAA receptor subunit genes is subject to differential regulation. Furthermore, developmental expression of the GABAA receptor alpha 6 subunit gene by these neurons is either a preprogrammed event or is initiated by an environmental cue that is received early in granule cell development, and it is not a result of afferent activation of ionotropic glutamate receptors.

Critical care-acquired pneumonia

Nosocomial infections are the second most common hospital-acquired infections. The Centers for Disease Control and Prevention recently published an updated Guidelines for the Prevention of Nosocomial Pneumonia. A summary of these recommendations and general preventive strategies are presented in this article.

Impact of age and environment on somatic mutation at the hprt gene of T lymphocytes in humans

Analysis of two human populations for dependence of somatic mutation on age has revealed both similarities and differences. The studies performed employed peripheral blood lymphocytes and measured the efficiency with which these cells form clones in vitro (cloning efficiency, CE) and the frequency of cells with inactivating mutations of the hypoxanthine phosphoribosyltransferase gene (mutant frequency, MF). The people studied were between 19 and 64 years of age. In one population, composed of 78 never smokers and 140 current smokers from the United States (US), both CE and MF were dependent on age: CE declined with age (p = 0.005); MF increased 0.15 per 10(6) cells per year of age for nonsmokers (p < 0.001) and at 1.3 times that rate for smokers (p = 0.01). In the second population, 80 people of unknown smoking status from Russia, the increase in MF per year was even greater, 2.5 times that of the US nonsmokers (p = 0.001) but the dependence of CE on age was the same as for the US population (p = 0.043). Because the increase of MF of the Russians with age is 2-fold greater than that of the US smokers, the intensity of smoking and/or other environmental exposures, or the susceptibility to these exposures, must account for the difference in age dependent MF increase, not the proportion of Russians that are smokers. Differences in the lymphocyte subpopulations that survived the longer transit from Russia may have contributed to the observed differences in MF. However, overall, the mutant frequency results suggest that the Russians were chronically exposed to higher levels of agents that induce somatic mutation and that, on an age adjusted basis, the Russia population studied is at increased risk for health consequences from accumulated genetic damage.

Quantitative characterization of alpha 6 and alpha 1 alpha 6 subunit-containing native gamma-aminobutyric acidA receptors of adult rat cerebellum demonstrates two alpha subunits per receptor oligomer

gamma-Aminobutyric acidA (GABAA) receptors were purified from adult rat cerebella by anti-alpha 6(1-16 Cys) antibody affinity chromatography. Immunoblots of the alpha 6 subunit-containing receptors showed the copurification of the alpha 1, beta 2/3, gamma 2, delta but not alpha 2 and alpha 3 GABAA receptor polypeptides. Further fractionation of this receptor subpopulation by anti-GABAA receptor subunit alpha 6(1-16 Cys) and anti-alpha 1(413-429) antibody affinity columns in series substantiated the coassociation of the alpha 1 and alpha 6 polypeptides. The percentage of coexistence of the two subunits was determined by quantitative immunoblotting, which found that 41 +/- 12% of alpha 6 subunit immunoreactivity is associated with the alpha 1 subunit. The ratios of the alpha 1:alpha 6 subunits in the double purified receptor preparations was found to be 1:1, thus determining directly for the first time subunit ratios within native GABAA receptors. The benzodiazepine pharmacology of the alpha 1 alpha 6 subunit-containing receptors was shown to be predominantly benzodiazepine-insensitive by quantitative immunoprecipitation assays. These results are the first direct quantitative studies of subunit ratios within a population of native GABAA receptors.

GABAA receptor subtypes expressed in cerebellar granule cells: a developmental study

The developmental properties of primary rat cerebellar granule cells have been characterised with respect to their expression of GABAA receptor subtypes using both an immunological approach and radioligand binding assays. At day 1 in culture, the GABAA receptor alpha 1 subunit was detectable in immunoblots and increased in level up to day 9. The GABAA receptor alpha 6 subunit was not detectable at day 1; however, at days 3-5, a specific M(r) 58,000 anti-alpha 6 1-16 Cys immunoreactive species was present which further increased in level up to 9 days in culture. Similar qualitative results were obtained for the expression of the GABAA receptor alpha 6 subunit in age-matched rat cerebellar membranes. In parallel studies, it was found that although there was an overall increase in [3H]Ro 15-4513 binding sites with days in culture, the relative contributions of diazepam-sensitive and diazepam-insensitive [3H]Ro 15-4513 binding changed. A time-dependent enrichment of the diazepam-insensitive binding site up to a maximum of 74% of total [3H]Ro 15-4513 sites was found. This was concomitant with the appearance of the GABAA receptor alpha 6 subunit. These results are in agreement with the pharmacology described for alpha 6 beta gamma 2 cloned receptors. They suggest a developmentally regulated expression of the GABAA receptor alpha 6 subunit gene at a time that is correlated in vivo with establishment of neuronal connections.

CYP1A1 mRNA levels as a human exposure biomarker: use of quantitative polymerase chain reaction to measure CYP1A1 expression in human peripheral blood lymphocytes

Accurate human risk assessment requires sensitive methods to evaluate dose-response relationships, especially following low level exposures. We have developed a reverse transcriptase polymerase chain reaction (RT-PCR) method to quantitative cytochrome P450-1A1 (CYP1A1) mRNA levels in human blood lymphocytes. Many polycyclic aromatic hydrocarbons (PAH) such as benzo[a]pyrene, and chlorinated PAH such as polychlorinated dibenzodioxins, dibenzofurans and biphenyls induce CYP1A1 expression through activation of an endogenous protein, the Ah receptor. Using a quantitative competitive RT-PCR method that included a synthetic internal standard we determined copy numbers of CYP1A1 mRNA in resting as well as mitogen-stimulated human blood lymphocytes. In mitogen-stimulated human blood lymphocytes assay variation was approximately 10% for measurement of this low expression gene and mRNA levels correlated well with ethoxyresorufin-O-deethylase (EROD) activity. The expression of mRNA was induced 20-fold upon culturing human lymphocytes with 10 nM TCDD. In nonstimulated, uninduced lymphocytes CYP1A1 levels are extremely low (1000 copies mRNA/10(4) cells) and cannot be measured by EROD activity. Studies of CYP1A1 mRNA expression in chemically-exposed populations are in progress.

Factors affecting HPRT mutant frequency in T-lymphocytes of smokers and nonsmokers

The frequency of thioguanine-resistant, hypoxanthine phosphoribosyltransferase-deficient lymphocytes in the peripheral blood of human subjects was used to study the genotoxic effects of smoking. Sixty-two nonsmokers and 58 smokers, aged 19 to 45 years with average ages of 30 and 32 years, respectively, and with no other known exposures, were studied using an in vitro assay of the frequency of mutant lymphocyte clones. Analysis of variance explained 68% of the variation in the mutant frequencies. Mutant frequency was dependent upon lymphocyte cloning efficiency, length of smoking history, age, and interactions between these variables. Four nonsmokers and three smokers had high mutant frequencies that were not explained by these variables. Mutant frequencies were inversely related to lymphocyte cloning efficiencies; the effect was twice as great for smokers as for nonsmokers. The time-dependent effect of smoking dominated, with mutant frequency increasing 10%/year of smoking as compared with an independent 1%/year of age. Smoking had a greater effect on young smokers' lymphocytes. Heterogeneity of mutant frequency among both smokers and nonsmokers and its implications for use of lymphocyte mutation assays as biomarkers are discussed.

Characterization of in vivo somatic mutations at the hypoxanthine phosphoribosyltransferase gene of a human control population

The ability to recognize a change in mutation spectrum after an exposure to a toxic substance and then relate that exposure to health risk depends on the knowledge of mutations that occur in the absence of exposure. Toward this end, we have been studying both the frequency and molecular nature of mutations of the hypoxanthine phosphoribosyltransferase (hprt) gene in peripheral blood lymphocytes as surrogate reporters of genetic damage. We have analyzed mutants, one per donor to ensure independence, from a control population in which the quantitative effects of smoking and age on mutant frequency have been well defined. Analyses of cDNA and genomic DNA by polymerase chain reaction and sequencing have identified the mutations in 63 mutants, 45 from males and 18 from females, of which 34 were smokers and 29 were nonsmokers. Slightly less than half of the mutations were base substitutions; they were predominantly at GC base pairs. Different mutations at the same site indicated that there are features of the hprt polypeptide that affect the mutation spectrum. Two pairs of identical mutations indicated that there may also be hot spots. Mutations not previously reported have been detected, indicating that the mutation spectrum is only partly defined. The remainder of the mutations were deletions or insertions/duplications; deletions ranged from one base pair to complete loss of the locus. Despite a small average increase in mutant frequency for smokers, an increased proportion of base substitutions at AT base pairs in smokers (p = 0.2) hinted at a smoking-associated shift in the mutation spectrum.(ABSTRACT TRUNCATED AT 250 WORDS)