Mitigating emotional responses to stressors: coping strategies, modifiers and support

OBJECTIVE

The stressful nature of the intensive care unit (ICU) environment is increasingly well characterised. The aim of this paper was to explore modifiers, coping strategies and support pathways identified by experienced Intensivists, in response to these stressors.

METHOD

Prospective qualitative study employing interviews with Intensivists in two countries. Participants were asked how they mitigated their emotional responses to the stressors of the ICU. Audio-recordings were transcribed and analysed by all researchers who agreed upon emerging themes and subthemes.

RESULTS

A wide range of strategies were reported. Although several participants had sought professional help and all supported its utility, few disclosed accessing such help to others indicating stigma. Many felt a sense of responsibility for the well-being of other staff but identified barriers that suggest alternate support pathways are required. Further implications of these findings to training considerations are described.

CONCLUSIONS

Several approaches were described as regularly employed by Intensivists to mitigate ICU environmental stressors. Intensivists perceive themselves to have limited training to provide support to others; they also perceive stigma in seeking professional help.

Behavioural responses of Intensivists to stressors in Intensive Care

BACKGROUND

The hospital intensive care unit (ICU) environment encompasses sick patients who present for care in health crisis. Healthcare in this setting is complex, often involving the co-ordination of multiple professional teams, all under significant time pressures. The sequelae for staff interacting in this dynamic and often volatile setting are variable, depending upon their coping skillset and their familiarity with the stressors.

AIMS

The primary aim of this study was to describe and in doing so, normalize the behavioural responses expressed by ICU doctors (Intensivists) in response to stressful workplace events. The secondary aim was to identify those responses that contributed to resilience.

METHODS

A prospective qualitative study of senior Intensivists using a semi-scripted iterative interview. Data were transcribed and thematically analysed with verbatim quotations selected to support coding choices.

RESULTS

Nineteen experienced Intensivists from three sites in Australia and Israel participated. Clinicians described conscious, physiological and professional responses to stressors, including sense-making and taking time to process information with appropriate support. Two of the most important mitigation processes revealed were the use of reflective learning and preventative practice changes to prevent future errors. These were overlaid with the importance of disclosure and transparency in clinical work.

CONCLUSIONS

Repeated exposure to stressful events potentiates burnout, wherein staff no longer experience satisfaction and enjoyment in what they do. This paper presents the behavioural responses that experienced Intensivists described in relation to stressful events in the ICU, including steps taken to mitigate the effects of these events on their personal well-being.

A Snapshot of the Oxygenation of Mechanically Ventilated Patients in One Australian Intensive Care Unit

Hyperoxaemia in patients undergoing mechanical ventilation (MV) has been found to be an independent predictor of worse outcome and in-hospital mortality in some conditions. Data suggests that a fraction of inspired oxygen (FiO2) of 0.4 or lower may produce hyperoxaemia although it is commonly accepted without adjustment in ventilator settings. The primary aim of this study was to observe current practice at one Australian tertiary intensive care unit (ICU) with regard to prescription and titration of oxygen (O2) in patients undergoing MV, in particular whether they received higher FiO2 than required according to arterial blood gas (ABG) results, and whether there was FiO2 titration as a response to initial ABG results during the 12 hours following. A retrospective observational study of 151 ICU patients undergoing MV between November 2013 and February 2014 was conducted, with ABGs as the primary outcome measure. There were 250 ABG measures, with mean FiO2 0.38 (range 0.3–1.0) and mean PaO2 114 mmHg (standard deviation 36). Over all observations, 197 (79%) were of FiO2 ≤0.4, however no patients were ventilated on room air (FiO2 0.21) and 114 (46%) were in the hyperoxaemic range. Oxygen titration (up or down) occurred in 31% of patients. Morning ABGs were taken at a time suggested by ICU guidelines, and on review of these measures, the mean FiO2 was lower than that purported to create toxicity. Subsequently, almost one-third of the cohort had their FiO2 titrated, however there was a floor effect whereby 39%–43% of the cohort received an FiO2 of 0.3.

Validation Of The HAS-BLED Tool In Atrial Fibrillation Patients Receiving Rivaroxaban

Background: Atrial fibrillation (Afib) patients are at an increased risk of stroke. Patients at moderate to high risk of stroke typically receive antithrombotics, placing them at an increased risk of bleeding. The HAS-BLED tool has been validated in Afib patients receiving warfarin for prediction of major bleeding events. Although HAS-BLED has been researched in patients receiving warfarin, this tool has not been validated with the novel anticoagulant rivaroxaban. Methods: The trial design was retrospective case-control approved by the Institutional Review Board at University of Tennessee Medical Center. Patients who were identified as having a bleeding event were cross-referenced with a list of patients receiving rivaroxaban. Inclusion criteria were adult patients with atrial fibrillation who were taking rivaroxaban for at least six months, with a CHA₂DS₂-VASc score greater than or equal to 2 OR CHADS₂ score greater than or equal to 1. The primary endpoint is the predictive ability of HAS-BLED as measured through the c-statistic. Secondary endpoints include correlation of HAS-BLED and bleeding risk. Results: After reviewing 9621 medical records, 15 patients met the inclusion criteria for major bleeding. Ninety patients were randomly selected for inclusion as the matched control group. The predictive ability of HAS-BLED was not statistically significant (c statistic = 0.68; p = 0.07), but did show some diagnostic ability to predict major bleeding events. Patients with major bleeding were more likely to have a history of bleeding and use concomitant antiplatelet agents. There were significantly more patients with a HAS-BLED score greater than or equal to 3 in the patients that experienced a major bleeding event. Conclusion: HAS-BLED demonstrated some diagnostic ability to predict major bleeding events in patients receiving rivaroxaban but this was not statistically significant due to limited sample size.

Mine waste disposal leads to lower coral cover, reduced species richness and a predominance of simple coral growth forms on a fringing coral reef in Papua New Guinea

A large gold mine has been operating at the Lihir Island Group, Papua New Guinea since 1997. The mine disposes of waste rock in nearshore waters, impacting nearby coral communities. During 2010, 2012 we conducted photographic surveys at 73 sites within 40 km of the mine to document impacts of mining operations on the hard coral communities. Coral communities close to the mine (∼2 km to the north and south of the mine) were depaurperate, but surprisingly, coral cover and community composition beyond this range appeared to be relatively similar, suggesting that the mine impacts were limited spatially. In particular, we found mining operations have resulted in a significant decrease in coral cover (4.4% 1.48 km from the disposal site c.f. 66.9% 10.36 km from the disposal site), decreased species richness and a predominance of less complex growth forms within ∼2 km to the north and south of the mine waste disposal site. In contrast to the two 'snapshot' surveys of corals performed in 2010 and 2012, long term data (1999-2012) based on visual estimates of coral cover suggested that impacts on coral communities may have been more extensive than this. With global pressures on the world's coral reefs increasing, it is vital that local, direct anthropogenic pressures are reduced, in order to help offset the impacts of climate change, disease and predation.

Proneural genes in neocortical development

Neurons, astrocytes and oligodendrocytes arise from CNS progenitor cells at defined times and locations during development, with transcription factors serving as key determinants of these different neural cell fates. An emerging theme is that the transcription factors that specify CNS cell fates function in a context-dependent manner, regulated by post-translational modifications and epigenetic alterations that partition the genome (and hence target genes) into active or silent domains. Here we profile the critical roles of the proneural genes, which encode basic-helix-loop-helix (bHLH) transcription factors, in specifying neural cell identities in the developing neocortex. In particular, we focus on the proneural genes Neurogenin 1 (Neurog1), Neurog2 and Achaete scute-like 1 (Ascl1), which are each expressed in a distinct fashion in the progenitor cell pools that give rise to all of the neuronal and glial cell types of the mature neocortex. Notably, while the basic functions of these proneural genes have been elucidated, it is becoming increasingly evident that tight regulatory controls dictate when, where and how they function. Current efforts to better understand how proneural gene function is regulated will not only improve our understanding of neocortical development, but are also critical to the future development of regenerative therapies for the treatment of neuronal degeneration or disease.

Ventilation - How Often are we Correct?

Traditional mechanical ventilation used tidal volumes (Vt) of between 10 to 15 ml/kg of body weight in order to achieve normal values of pH and partial pressure of carbon dioxide (PaCO2). Many clinicians today however, adopt lower volumes as a conservative ‘safe’ ventilation strategy in most mechanically ventilated patients. The method by which this is done varies between facilities, but anecdotally doctors use Vt of 6 to 8 ml/kg, and they commonly estimate these volumes at the bedside. This observational study was undertaken in a 23-bed level 3 intensive care unit at a metropolitan tertiary hospital in order to determine whether or not intensive care clinicians are accurately determining the Vt during mechanical ventilation which they purport to do. The primary outcome measure was the Vt being delivered at the time of observation. Thirty patients were recruited into the study, resulting in 55 observations of synchronised intermittent mandatory ventilation with autoflow mode ventilator settings. Although volumes between 6 to 8 ml/kg were recorded in 33 (60%) observations, more detailed exploration of the individual's clinical circumstances reflects that the actual dialled volumes were correct in all but two patients. Intensive care unit mortality was 13% (n=2) in those patients receiving higher than anticipated Vts (n=15). This study has demonstrated that while we achieve a protective ventilation strategy by adopting lower Vts in most mechanically ventilated patients, we should be constantly monitoring exactly what volume is being achieved, not just what is dialled up to be delivered.

Information needs across the colorectal cancer care continuum: scoping the literature

Because cancer care requires a multifaceted approach, providing useful and timely information to people with colorectal cancer may be fragmented and inconsistent. Our interest was in examining what has and has not captured the attention of researchers speaking to the information needs of people with colorectal cancer. We followed Arksey and O'Malley's framework for the methodology of scoping review. Focusing solely on colorectal cancer, we analysed 239 articles to get a picture of which information needs and sources of information, as well as the timing of providing information, were attended to. Treatment-related information received the most mentions (26%). Healthcare professionals (49%) were mentioned as the most likely source of information. Among articles focused on one stage of the care continuum, post-treatment (survivorship) received the most attention (16%). Only 27% of the articles consulted people with colorectal cancer and few attended to diet/nutrition and bowel management. This study examined the numerical representation of issues to which researchers attend, not the quality of the mentions. We ponder, however, on the relationship between the in/frequency of mentions and the actual information needs of people with colorectal cancer as well as the availability, sources and timing of information.

Interaction of PLGA nanoparticles with human blood constituents

When nanoparticles are injected into the blood for drug delivery or drug detoxification, detrimental interaction of these particles with blood constituents must be avoided. In previous studies, the adsorption of albumin immunoglobulin G, and fibrinogen from blood plasma to a model hydrophobic polymer like polystyrene was investigated as was decreasing surface hydrophobicity, which quantitatively leads to decreasing amounts of adsorbed proteins on latex particles. However, the uptake of other blood constituents, such as inorganic blood electrolytes, by particles and the dispersion/coagulation characteristics of these particles in the blood stream have not been fully studied. Most importantly, the effect s of these particles on blood coagulation and hemolysis are not well known. In the present study, the poly(lactide-co-glycolide) acid(PLGA) nanoparticles were synthesized by using nanoprecipitation. The uptake of blood electrolytes from simulated blood fluid (SBF) and the stability (dispersion/aggregation) of nanoparticles in SBF was examined by using different loading amounts of PLGA and different contact time between PLGA nanoparticles and SBF. The interaction of particles with the organic components of blood was also studied by using the measurement of red blood cell hemolysis and blood clotting with raw PLGA, surfactant modified PLGA, and PEGylated PLGA.

Time-limited assertive community treatment for homeless persons with severe mental illness

BACKGROUND

The assertive community treatment (ACT) model for people with severe mental illness was originally designed to be provided continuously without termination. This study evaluated postdischarge changes in health status and service use associated with the time-limited provision of ACT to homeless people with severe mental illness.

METHODS

Clients in the fourth annual cohort of the Access to Community Care and Effective Services and Supports (ACCESS) program (N = 1617) were assessed at entry into ACT and 3, 12, and 18 months later. Random effects models were used to compare outcomes and service use among clients who terminated ACT and clients who remained in ACT, controlling for potentially confounding factors.

RESULTS

Altogether, of clients who participated in follow-up, 8.7% participated for less than 3 months; 40.6%, for 3 to 10 months; 15.3%, for 11-13 months; and 35.3%, for 14 months or more. Controlling for potentially confounding factors, mental health, substance abuse, and housing outcomes did not significantly differ between clients who had been discharged at the time of follow-up as compared with those who had not. Those who had been discharged had worked significantly more days than those who had not (t(1794) = 3.24, P<.001), and they reported significantly less outpatient health service use though there was no decline in hospital days or receipt of public support payments.

CONCLUSION

Homeless clients who have severe mental illness can be selectively discharged or transferred from ACT to other services without subsequent loss of gains in mental health status, substance abuse, housing, or employment.

Concurrent use of reteplase and lepirudin in the treatment of acute anterior wall myocardial infarction

A 61-year-old male with a history of severe heparin-induced thrombocytopenia (HIT) type II after aorto-femoral bypass surgery presented to the emergency department within 8 hours of development of substernal chest pain radiating to the left arm. Electrocardiogram (ECG) on arrival and at 3 hours showed no acute changes; cardiac enzymes revealed minimal MB elevation. Echocardiogram showed normal left ventricular systolic function with mild mitral and tricuspid regurgitation and trace aortic insufficiency. Five hours after arrival, the patient reported a recurrence of severe chest pain. ECG showed marked ST elevations consistent with acute myocardial infarction. Reteplase was administered with concomitant lepirudin. Follow-up ECG showed improvement in ST-segment elevation and eventual resolution to pre-event tracing; cardiac enzymes showed slight elevations. Catheterization revealed 90% midstenosis of the left anterior descending artery, which was successfully treated with percutaneous transluminal coronary angioplasty (PTCA) and stent placement. Repeat PTCA was performed 10 days postdischarge due to intraluminal stent occlusion. The patient was doing well at 6 months follow-up.

Assessing the New York City involuntary outpatient commitment pilot program

OBJECTIVE

The study evaluated the effectiveness of a three-year outpatient commitment pilot program established in 1994 at Bellevue Hospital in New York City.

METHODS

A total of 142 participants were randomly assigned; 78 received court-ordered treatment, which included enhanced services, and 64 received the enhanced-service package only. Between 57 and 68 percent of the subjects completed interviews at one, five, and 11 months after hospital discharge. Outcome measures included rehospitalization, arrest, quality of life, symptomatology, treatment noncompliance, and perceived level of coercion.

RESULTS

On all major outcome measures, no statistically significant differences were found between the two groups. No subject was arrested for a violent crime. Eighteen percent of the court-ordered group and 16 percent of the control group were arrested at least once. The percentage rehospitalized during follow-up was about the same for both groups-51 percent and 42 percent, respectively. The groups did not differ significantly in the total number of days hospitalized during the follow-up period. Participants' perceptions of their quality of life and level of coercion were about the same. From the community service providers' perspective, patients in the two groups were similarly adherent to their required treatments.

CONCLUSIONS

All results must be qualified by the fact that no pick-up order procedures for noncompliant subjects in the court-ordered group were implemented during the study, which compromised the differences between the conditions for the two groups, and that persons with a history of violence were excluded from the program.

An interactive system for kinematic analysis of artificial joint implants

The objective of this project was to develop and test a software system for the kinematic analysis of total joint arthroplasty (TJA) implants. Using a supervised iterative optimization algorithm (simulated annealing), the system iteratively adjusts the pose of an implant model to maximize correlation between the model's pose and the pose of an actual implant in a x-ray image. A graphical user interface (GUI) was developed that provides visualization of the model-fitting process, and permits human guidance for error correction. The resulting system was evaluated to determine its accuracy and repeatability. On synthetic images, the mean translational and rotational errors were found to be 0.005 mm and 0.0015 degrees, respectively. On in vitro images, the repeatability was found to be 0.15 mm of translation and 0.17 degrees of rotation. The outcome is a working joint-measurement software system and quantitative data to support comparison with other methods.

A multi-year evaluation of a parent support centre

This paper summarizes the results of a multi-year evaluation of a parent support centre project. Qualitative data gathered both from a series of individual interviews with participants and from a series of focus-group interviews with both participants and workers are presented. The developmental process of the project is detailed. Positive outcomes with regard to individual changes in social support, parenting, and self-esteem are described. The accomplishments of the project's goals regarding participant satisfaction with activities and programs and the development of indigenous leadership are noted; however, the project was deemed less successful with regard to ongoing recruitment of participants. Implications for practice are discussed.

Sequence of PHA synthase gene from two strains of Rhodospirillum rubrum and in vivo substrate specificity of four PHA synthases across two heterologous expression systems

A 3.0-kb genomic fragment has been isolated from Rhodospirillum rubrum (ATCC 25903) that contains an open reading frame (ORF) with strong homology to other known polyhydroxyalkanoate (PHA) synthase genes. This ORF has lower homology to the R. rubrum strain Ha PHA synthase than would be expected within the same species. We have conducted a series of heterologous expression studies evaluating the in vivo substrate specificity of PHA synthase genes from Rhodobacter sphaeroides, Ralstonia eutropha (formerly Alcaligenes eutrophus), Thiocystis violacea, and Nocardia corrallina, within the PHA-synthase-negative hosts, Ralstonia eutropha DSM541 and Pseudomonas putida GpP104. The N. corrallina PHA synthase incorporated the highest percentage of C5 monomers in the polymer when fermented in medium supplemented with 0.1% heptanoate as the sole carbon source. When the T. violacea and R. sphaeroides were expressed in the PHA-negative host DSM541, a greater percentage of C5 monomer was observed in the polymer as compared to the expression of the PHA synthase of R. eutropha, when the transconjugants were fermented in medium supplemented with 0.4% propionate. Evaluation for preference of medium-chain-length monomers demonstrated the flexibility of the N. corrallina, T. violacea, and R. eutropha synthase genes to polymerize a copolyester composed of short- and medium-chain-length monomers when the respective transconjugants were fermented in medium supplemented with 0.5% octanoate. These studies demonstrate that the PHA synthase from N. corrallina, T. violacea, and R. eutropha are able to polymerize a copolyester composed of short- and medium-chain-length monomers, while the PHA synthase from R. sphaeroides lacks this ability and only produces a short-chain-length polymer. These observations suggest that the composition of the PHA from the PHA-producing organisms does not necessarily reflect the inherent specificity of the PHA synthase.

Cloning, molecular analysis, and expression of the polyhydroxyalkanoic acid synthase (phaC) gene from Chromobacterium violaceum

The polyhydroxyalkanoic acid synthase gene from Chromobacterium violaceum (phaC(Cv)) was cloned and characterized. A 6.3-kb BamHI fragment was found to contain both phaC(Cv) and the polyhydroxyalkanoic acid (PHA)-specific 3-ketothiolase (phaA(Cv)). Escherichia coli strains harboring this fragment produced significant levels of PHA synthase and 3-ketothiolase, as judged by their activities. While C. violaceum accumulated poly(3-hydroxybutyrate) or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) when grown on a fatty acid carbon source, Klebsiella aerogenes and Ralstonia eutropha (formerly Alcaligenes eutrophus), harboring phaC(Cv), accumulated the above-mentioned polymers and, additionally, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) when even-chain-length fatty acids were utilized as the carbon source. This finding suggests that the metabolic environments of these organisms are sufficiently different to alter the product range of the C. violaceum PHA synthase. Neither recombinant E. coli nor recombinant Pseudomonas putida harboring phaC(Cv) accumulated significant levels of PHA. Sequence analysis of the phaC(Cv) product shows homology with several PHA synthases, most notably a 48% identity with that of Alcaligenes latus (GenBank accession no. AAD10274).

Aqueous release and purification of poly(beta-hydroxybutyrate) from Escherichia coli

The poly(beta-hydroxybutyrate) (PHB) biosynthetic genes of Ralstonia eutropha that are organized in a single operon (phaCAB) have been cloned in Escherichia coli, where the expression of the genes in the wild-type pha operon from plasmid pTZ18U-PHB leads to the formation of 50-80% PHB/celldry mass when the cells are grown in Luria-Bertani medium supplemented with 1% glucose (w/v). In combination with the phaCAB genes, expression of cloned lysis gene E of bacteriophage PhiX174 from plasmid pSH2 has been used to release PHB granules produced in E. coli. It was shown that small PHB granules in a semiliquid stage are squeezed out of the cells through the E-lysis tunnel structure which is characterized by a small opening in the envelope with borders of fused inner and outer membranes. All envelope components remain intact after E-lysis and can be removed from the mixture of released PHB granules by density gradient centrifugation. In addition, a modified E-lysis procedure is described which enables the release of PHB from cell pellets in pure water or low ionic strength buffer. PHB granules in aqueous solution can be aggregated by divalent cations. Addition of glassmilk speeds up the agglomeration of PHB granules and binding to glass beads can either be used for collection or further purification of PHB in aqueous solutions.

Protein organization on the PHA inclusion cytoplasmic boundary

Polyhydroxyalkanoate (PHA) cellular inclusions consist of polyesters, phospholipids, and proteins. Both the polymerase and the depolymerase enzymes are active components of the structure. Recently, proteins associated with these inclusions have been described in a number of bacterial species. In order to further clarify the structure and function of these proteins in relation to polymer inclusions, ultrastructural studies of isolated polymer inclusions were initiated. The surface boundary characteristics of polymer inclusions, produced by several genera of bacteria, two different Pseudomonas putida deletion mutants and by Escherichia coli recombinants, were examined. The recombinant E. coli carried either the PHB biosynthesis operon (phaCAB) from Ralstonia eutropha alone, or both this operon and a gene encoding an inclusion surface protein of R. eutropha (phaP). The results support two suggestions: (i) specific genes in the PHA gene cluster code for the proteins forming the surface boundary arrays which characterize the polymer inclusion; and (ii) transfer of such a gene would result in subcellular compartmentalization of accumulating polymer. Although the proteins appear to serve a similar function among different genera, nevertheless, the different surface proteins are encoded by a variety of non-homologous genetic sequences.

Formation of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) by PHA synthase from Ralstonia eutropha

The acetoacetyl-CoA reductase and the polyhydroxyalkanoate (PHA) synthase from Ralstonia eutropha (formerly Alcaligenes eutrophus) were expressed in Escherichia coli, Klebsiella aerogenes, and PHA-negative mutants of R. eutropha and Pseudomonas putida. While expression in E. coli strains resulted in the accumulation of poly(3-hydroxybutyrate) [PHB], strains of R. eutropha, P. putida and K. aerogenes accumulated poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [poly(3HB-co-3HHx)] when even chain fatty acids were provided as carbon source, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [poly(3HB-co-3HV)] when odd chain fatty acids were provided as carbon source. This suggests that fatty acid degradation can be directly accessed employing only the acetoacetyl-CoA reductase and the PHA synthase. This is also the first proof that the PHA synthase from R. eutropha can incorporate 3-hydroxyhexanoate (3HHx) into PHA and has, therefore, a broader substrate specificity than previously described.

Investigation of the function of proteins associated to polyhydroxyalkanoate inclusions in Pseudomonas putida BMO1

Polyhydroxyalkanoate (PHA) granule associated proteins from Pseudomonas oleovorans were purified and the N-terminal sequences of two major proteins migrating in sodium dodecyl sulfate polyacrylamide gels with a relative molecular mass of 18 and 43 kDa (GA1 and GA2, respectively) were analyzed. Radiolabeled degenerate probes deduced from these amino acid sequences were used to identify genomic DNA fragments from P. oleovorans and Pseudomonas putida encoding GA1 and GA2. DNA sequence analysis of the fragments obtained from P. putida revealed that the genes encoding these proteins were adjacent to phaC2 and ORF3, the PHA synthase II gene and an open reading frame of unknown function, respectively, found at the P. oleovorans and P. aeruginosa PHA synthase gene locus. The open reading frames encoding GA1, GA2 and ORF3 or smaller fragments beginning at GA1 were inactivated by chromosomal insertion of the Tn5 kanamycin resistance gene block (neo). When these mutants were grown on mineral salts agar media under nitrogen limitation, containing gluconate or decanoate as carbon sources, they appeared more translucent than the wild-type grown under similar conditions. Gas-chromatographic analysis of the cellular dry mass revealed that the mutant strains accumulated 30-50% less PHA than the P. putida wild type.

Biologic activity of interleukin 1 (IL-1) alpha in patients with refractory malignancies

Interleukin 1 alpha (IL-1 alpha) is a cytokine with pleiotropic effects, including cytotoxic-cytostatic activity against some tumor cell lines. We have conducted a phase I study of recombinant human IL-1 alpha (rhIL-1 alpha) in 17 patients with refractory malignancies to examine its toxicity and biologic activity. rhIL-1 alpha was given as a 2-h IV infusion daily for 5 days at five dose levels (0.08, 0.2, 0.8, 2.0, and 5.0 micrograms/m2). Seventeen patients with malignancies were treated, with no objective tumor responses noted. Common toxicities included: fever (100%), rigors and/or chills (96%), myalgia (54%), and headache (48%). Three patients developed grade III hypotension. The maximum tolerated dose was 2.0 micrograms/m2. rhIL-1 alpha induced a significant increase in absolute neutrophil count over baseline (p < 0.05), a delayed but significant increase in platelet count over baseline (p < 0.05), and there was a marked increase in the number of progenitors [colony-forming units (CFU)-G, CFU-M, CFU-GM, CFU-GEMM and burst-forming units (BFU-E)] observed in the peripheral blood. Nine of 12 evaluable patients showed an increase in bone marrow cellularity or myeloid:erthyroid ratio. Immunophenotyping did not demonstrate an increase in peripheral blood or bone marrow CD34+ cells. Interferon-gamma-mediated monocyte cytotoxicity (MCCTX) was significantly enhanced from baseline (p < 0.001), although an increase in direct MCCTX did not reach statistical significance. In summary, rhIL-1 alpha administration is well tolerated at a dose of 2.0 micrograms/m2 with fever, rigors, myalgia, and headache being the most frequent toxicities. Although there were no objective tumor responses, we have demonstrated significant biologic activity with increased neutrophil and platelet counts, increased peripheral blood progenitor cells, and enhanced interferon-gamma-mediated MCCTX.

Cloning of the Nocardia corallina polyhydroxyalkanoate synthase gene and production of poly-(3-hydroxybutyrate-co-3-hydroxyhexanoate) and poly-(3-hydroxyvalerate-co-3-hydroxyheptanoate)

The polyhydroxyalkanoate (PHA) synthase gene (phaCNc) from Nocardia corallina was identified in a lambda library on a 6-kb BamHI fragment. A 2.8-kb XhoII subfragment was found to contain the intact PHA synthase. This 2.8-kb fragment was subjected to DNA sequencing and was found to contain the coding region for the PHA synthase and a small downstream open reading frame of unknown function. On the basis of DNA sequence, phaCNc is closest in homology to the PHA synthases (phaCPaI and phaCPaII) of Pseudomonas aeruginosa (approximately 41% identity and 55% similarity). The 2.8-kb XhoII fragment containing phaCNc was subcloned into broad host range mobilizable plasmids and transferred into Escherichia coli, Klebsiella aerogenes (both containing a plasmid bearing phaA and phaB from Ralstonia eutropha), and PHA-negative strains of R. eutropha and Pseudomonas putida. The recombinant strains were grown on various carbon sources and the resulting polymers were analyzed. In these strains, the PHA synthase from N. corallina was able to mediate the production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) containing high levels of 3-hydroxyhexanoate when grown on hexanoate and larger even-chain fatty acids and poly(3-hydroxyvalerate-co-3-hydroxyheptanoate) containing high levels of 3-hydroxyheptanoate when grown on heptanoate or larger odd-chain fatty acids.

Photoaffinity labeling by 4-thiodideoxyuridine triphosphate of the HIV-1 reverse transcriptase active site during synthesis. Sequence of the unique labeled hexapeptide

The active site of HIV-1 reverse transcriptase (HIV-1 RT) was investigated by photoaffinity labeling based on catalytic competence. A stable ternary elongation complex was assembled containing enzyme, DNA template (RT20), DNA primer molecule (P12), and the necessary dNTPs (one of which was alpha-32P-labeled) needed for primer elongation. The photoaffinity probe 4-thiodideoxyuridine triphosphate was incorporated uniquely at the 3' terminus of the 32P-labeled DNA product. Upon photolysis, the p66 subunit of a HIV-1 RT heterodimer (p66/p51) was uniquely cross-linked to the DNA product and subsequently digested by either trypsin or endoproteinase Lys-C. The labeled HIV-1 RT peptide was separated, purified, and finally subjected to Edman microsequencing. A unique radioactive hexapeptide (V276RQLCK281) was identified and sequenced. Our photoaffinity labeling results were positioned on the HIV-1 RT. DNA.Fab complex x-ray crystallography structure and compared with the suggested aspartic triad active site.

Production of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) in recombinant Escherichia coli grown on glucose

A recombinant Escherichia coli strain has been developed that produces poly(3-hydroxybutyrate-co-4-hydroxybutyrate) when grown in complex medium containing glucose. This has been accomplished by introducing into E. coli DH5 alpha separate plasmids harboring the polyhydroxyalkanoate (PHA) biosynthesis genes from Ralstonia eutropha (formerly named Alcaligenes eutrophus) and the succinate degradation genes from Clostridium kluyveri, respectively. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) levels reached 50% of the cell dry weight and contained up to 2.8 mol.% 4-hydroxybutyrate. The molecular weight of the polymer was 1.8 x 10(6).

Housing outcomes for homeless adults with mental illness: results from the second-round McKinney program

In the early 1990s the National Institute of Mental Health sponsored projects in four cities that served a total of 896 homeless mentally ill adults. Each project tested the effectiveness of different housing, support, and rehabilitative services in reducing homelessness. Most homeless individuals resided in community housing after the intervention. The proportion in community housing varied between sites. A 47.5 percent increase in community housing was found for those in active treatment conditions. At final follow-up, 78 percent of participants in community housing were stably housed. The findings indicate that effective strategies are available for serving homeless individuals with severe mental illness.

AIDS and the new medical gaze: bio-politics, AIDS, and homosexuality

The essay argues that the contemporary resurgence of homophobia and the remedicalization of homosexuals in the wake of AIDS is, in part, an unintended but predictable effect of a quarter century of fractious identity-politics. Prominent gay and lesbian political strategies of the 1970s and 1980s borrowed heavily from increasingly discredited, if once politically correct, discourses that valorized individuals on the basis of membership in governmentally constructed bio-bureaucratic categories. Drawing on the work of prominent gay intellectuals, such as Foucault, Watney, and Richard Rodriguez, and locating their insights within the context of contemporary cultural and political conflicts, the essay argues that gay advocates who essentialize homosexual identity, however benignly, unwittingly participate in constituting the ground for an emergence of a neoeugenic movement at millennium's end. The essay concludes with the observation that escaping the conceptual prison of bio-bureaucratic categories is not a uniquely gay or lesbian task. It is a human task.

Application of an optimized electroporation procedure for replacement of the polyhydroxyalkanoate synthase I gene in Nocardia corallina

To develop a system for gene replacement in Nocardia corallina, a protocol for electroporation was optimized by systematic alterations of growth conditions, field strength, time constant and the electroporation buffer. Transformation efficiencies of 0.5 x 10(6) - 3 x 10(6) transformants/microgram plasmid DNA were obtained routinely. The gene encoding the polyhydroxyalkanoate (PHA) synthase I of N. corallina was cloned and interrupted by insertion of a kanamycin-resistance gene. The resulting plasmid was introduced into N. corallina by electroporation to inactivate the wild-type gene by homologous recombination. Kanamycin-resistant clones were screened by Southern hybridization for the absence of the wild-type gene and analyzed for PHA accumulation.

Metabolic pathway for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) formation in Nocardia corallina: inactivation of mutB by chromosomal integration of a kanamycin resistance gene

The gene encoding the large subunit of the methylmalonyl-coenzyme A (CoA) mutase in Nocardia corallina (mutBNc) was cloned. A 4.3-kbp BamHI fragment containing almost the entire mutBNc was identified by Southern hybridization experiments employing a digoxigenin-labeled probe deduced from mutB of Streptomyces cinnamonensis, mutBNc was interrupted by insertion of a kanamycin resistance gene block (mutB::kan or mutB::neo) and introduced into N. corallina to obtain mutB-negative strains by homologous recombination. Four of sixteen kanamycin-resistant clones occurred via double-crossover events and harbored only the interrupted mutBNc. These exhibited no growth on odd-chain fatty acids in the presence of kanamycin but exhibited wild-type growth on even-chain fatty acids, glucose, and succinate. Whereas the wild type of N. corallina accumulates a copolyester of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) containing more than 60 mol% 3HV from most carbon sources, mutB-negative strains accumulated poly(3HB-co-3HV) containing only 2 to 6 mol% 3HV. Methylmalonyl-CoA mutase activity was not found in these clones. Therefore, this study provides strong evidence that the majority of 3HV units in poly(3HB-co-3HV) accumulated by N. corallina are synthesized via the methylmalonyl-CoA pathway.

The function of ackA and pta genes is necessary for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in recombinant pha+ Escherichia coli

In Escherichia coli carrying the poly(3-hydroxyalkanoate) (PHA) biosynthesis pathway on a plasmid (pha+), the function of the ackA (acetate kinase) and pta (phosphotransacetylase) genes is necessary for efficient incorporation of 3-hydroxyvalerate (3-HV) into the copolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)). Recombinant pha+ E. coli fadR atoC(Con) strains possessing mutations in ackA, pta, or both ackA and pta exhibited substantially reduced levels of 3-HV formation. Conversely, the same strains carrying the ackA gene on a multicopy plasmid exhibited an increase in 3-HV formation concomitant with a large increase in acetate kinase activity. However, if the strain possessing the multicopy ackA+ plasmid was mutant at the pta locus, it lost the ability to incorporate significant amounts of 3-HV into P(3HB-co-3HV). In addition to the ackA pta pathway, there is an inducible activity that can also mediate the incorporation of 3-HV into P(3HB-co-3HV). This pathway is repressed by glucose and is not normally operative in P(3HB-co-3HV) production in recombinant pha+ E. coli strains that are grown using glucose as the major carbon source. It appears likely that this activity is due to an inducible acetyl-CoA synthetase that converts propionate to propionyl-CoA.

1,3-Dipropyl-8-[2-(5,6-epoxy)norbornyl]xanthine, a potent, specific and selective A1 adenosine receptor antagonist in the guinea pig heart and brain and in DDT1MF-2 cells

The objective of this study was to characterize the adenosine receptor (AdoR) antagonistic properties of a newly synthesized alkylxanthine, 1,3-dipropyl-8[2-(5,6-epoxy)norbornyl]xanthine (ENX), and compare them to those of 1,3-dipropyl-8-(cyclo-pentyl)xanthine (CPX), 1,3-dipropyl-8-(3-noradamantyl)xanthine (NAX) and (+/-)-N6-endo-norbornan-2-yl-9-methyladenine (N-0861). The potencies and selectivities of ENX, CPX, NAX and N-0861 were determined by functional studies of guinea pig isolated perfused hearts, and by radioligand binding assays for A1 and A2a AdoRs in the guinea pig forebrain and striatum. ENX competitively antagonized A1 AdoR-mediated prolongations of atrioventricular nodal conduction time caused by Ado or by 2-chloro-N6-cyclopentyladenosine, but not those caused by carbachol (0.14 microM) or MgCl2 (3 mM). Schild analysis of 2-chloro-N6-cyclopentyladenosine-antagonist competition curves yielded pA2 values for ENX, CPX and NAX of 8.45 +/- 0.19, 8.55 +/- 0.28 and 8.79 +/- 0.15, respectively. ENX (30 microM) and N-0861 (30 microM) did not attenuate the A2 AdoR-mediated increase in coronary conductance caused by adenosine. CPX and NAX attenuated the coronary vasodilation caused by adenosine with IC50 values of 1.5 and 7.1 microM, respectively. Radioligand binding assays revealed that ENX, CPX and NAX and N-0861 had a 400-, 209-, 110- and 10-fold greater affinity, respectively, for A1 than for A2a AdoRs of guinea pig brain membranes. Thus, ENX was equipotent with CPX and NAX and more potent than N-0861 (pA2 = 6.2) as an antagonist at A1 AdoRs, but had lower affinity for A2 AdoRs in guinea pig hearts and brain striatum than did either CPX or NAX. In DDT1 MF-2 cells, all three alkylxanthines had similar affinities for A1 AdoRs, whereas the affinity of N-0861 for A1 AdoRs was significantly lower. ENX appears to be the most A1 AdoR subtype-selective of the alkylxanthine class of AdoR antagonists reported to date.

Role of fadR and atoC(Con) mutations in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) synthesis in recombinant pha+ Escherichia coli

Recombinant Escherichia coli fadR atoC(Con) mutants containing the polyhydroxyalkanoate (PHA) biosynthesis genes from Alcaligenes eutrophus are able to incorporate significant levels of 3-hydroxyvalerate (3HV) into the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)]. We have used E. coli fadR (FadR is a negative regulator of fatty acid oxidation) and E. coli atoC(Con) (AtoC is a positive regulator of fatty acid uptake) mutants to demonstrate that either one of these mutations alone can facilitate copolymer synthesis but that 3HV levels in single mutant strains are much lower than in the fadR atoC(Con) strain. E. coli atoC(Con) mutants were used alone and in conjunction with atoA and atoD mutants to determine that the function of the atoC(Con) mutation is to increase the uptake of propionate and that this uptake is mediated, at least in part, by atoD+. Similarly, E. coli fadR mutants were used alone and in conjunction with fadA, fadB, and fadL mutants to show that the effect of the fadR mutation is dependent on fadB+ and fadA+ gene products. Strains that were mutant in the fadB or fadA locus were unable to complement a PHA biosynthesis pathway that was mutant at the phaA locus (thiolase), but a strain containing a fadR mutation and which was fadA+ fadB+ was able to complement the phaA mutation and incorporated 3HV into P(3HB-co-3HV) to a level of 29 mol%.

Regulated expression of the Alcaligenes eutrophus pha biosynthesis genes in Escherichia coli

A novel poly-beta-hydroxybutyrate (PHB) production system in which the expression and gene dosage of the Alcaligenes eutrophus pha biosynthetic operon were effectively regulated by cultivation temperature was constructed in Escherichia coli. The pha operon was fused to the negatively regulated tac promoter and cloned into a vector in which the copy number is temperature dependent. A two-phase process was employed to produce PHB during fed-batch growth. In the growth phase, the culture was maintained at a low temperature. Under this condition, the plasmid copy number was depressed and the number of LacI proteins was sufficient to repress tacupha transcription. The production phase was initiated by temperature upshift. At the elevated temperature, the number of plasmids surpassed the number of LacI repressors, which resulted in rapid induction of tacupha transcription, synthesis of poly-beta-hydroxyalkanoate-specific proteins, and polymer synthesis. During the production phase, the PHB production rate was 1.07 g of PHB liter-1 h-1 under optimized conditions. This rate is comparable to that of bacteria which naturally produce this polymer.

The cardiac effects of a novel A1-adenosine receptor agonist in guinea pig isolated heart

Adenosine increases atrioventricular (AV) nodal conduction time and is used for termination of AV nodal re-entrant tachycardias, but it is rapidly metabolized. The purposes of the present study were to characterize the cardiac actions and effects of an orally active and stable adenosine analog, N6-cyclohexyl-2-O-methyladenosine (SDZ WAG-994) and to evaluate its potential as an antiarrhythmic agent. Guinea pig hearts were isolated and perfused with oxygenated Krebs-Henseleit solution. SDZ WAG-994 slowed the atrial rate and prolonged the AV nodal conduction time of spontaneously beating hearts in a concentration-dependent manner. The EC50 values for the negative chronotropic and dromotropic effects of SDZ WAG-994 were 0.69 +/- 0.04 and 1.49 +/- 0.54 microM, respectively. The A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (0.2 microM) significantly antagonized SDZ WAG-994-induced stimulus-to-His bundle (S-H) interval prolongation. The negative dromotropic effect of SDZ WAG-994 showed very strong frequency dependence. In hearts paced at an atrial cycle length of 300 msec (200 beats/min), the EC50 value of SDZ WAG-994 to prolong the S-H interval was 3.7-fold lower (0.40 +/- 0.02 microM) than in unpaced hearts, and at atrial pacing cycle lengths of 500 and 250 msec, 0.3 microM SDZ WAG-994 prolonged the S-H interval by 8 and 26 msec, respectively. SDZ WAG-994 also decreased coronary perfusion pressure (EC50 = 1.50 +/- 0.80 microM); this effect of SDZ WAG-994 was attenuated by adenosine deaminase and by 8-cyclopentyltheophylline (2 microM). Radioligand binding assays revealed that SDZ WAG-994 had a 280-fold greater affinity for A1- than for A2a receptors of the guinea pig brain. The marked frequency dependence of the negative dromotropic effect of SDZ WAG-994 suggests that this A1 agonist may be highly effective in the termination of AV nodal re-entrant tachycardias.

Allosteric enhancer PD 81,723 acts by novel mechanism to potentiate cardiac actions of adenosine

The 2-amino-3-benzoylthiophene derivative PD 81,723 is an allosteric enhancer of agonist binding to brain A1 adenosine receptors. One aim of this study was to characterize and contrast the effects of PD 81,723 on the A1 receptor-mediated negative dromotropic and A2a receptor-mediated vasodilatory actions of adenosine and of a nonmetabolizable and unselective N6-(3-pentyl)adenosine derivative. A second aim was to determine the mechanism of action of PD 81,723. In guinea pig isolated hearts, PD 81,723 potentiated the adenosine and the N6-(3-pentyl)adenosine derivative-induced prolongations of the stimulus-to-His bundle (S-H) interval in a concentration-dependent manner. PD 81,723 (30 mumol/L) decreased the EC50 value for adenosine to prolong the S-H interval by ninefold from 7.4 +/- 1.2 to 0.8 +/- 0.1 mumol/L but did not increase the content of adenosine in cardiac effluent. PD 81,723 (30 mumol/L) increased the specific binding of the A1 agonist [3H]cyclohexyladenosine ([3H]CHA) to human atrial and guinea pig atrial and brain membranes by 38%, 78%, and 300%, respectively. PD 81,723 also increased the fraction of A1 receptors in the high-affinity binding state by an average of 56 +/- 13%. The dissociation rate of [3H]CHA from guinea pig brain membranes was decreased in the presence of PD 81,723 (10 mumol/L) from 0.55 +/- 0.01/min to 0.35 +/- 0.01/min. PD 81,723 did not alter the binding of the A1 antagonist [3H]cyclopentyldipropylxanthine to guinea pig brain membranes. The IC50 values for 5'-guanylylimidodiphosphate to reduce specific binding of [3H]CHA to guinea pig cardiac and brain membranes were increased from 1.5 +/- 0.2 and 2.0 +/- 0.2 mumol/L in the absence of PD 81,723 to 10 +/- 3.3 and 18 +/- 0.5 mumol/L, respectively, in the presence of PD 81,723 (30 mumol/L). PD 81,723 did not potentiate the coronary vasodilatory actions of the N6-(3-pentyl)adenosine derivative. Specific binding of the A2a agonist [3H]CGS 21680 to brain membranes and the nucleoside transporter ligand [3H]nitrobenzylthioinosine to cardiac membranes was unchanged in the presence of PD 81,723. The results suggest that PD 81,723 specifically potentiates the action of adenosine on A1 receptors by stabilizing receptor-G protein interactions in the presence of agonists.

Production of polyhydroxyalkanoates in sucrose-utilizing recombinant Escherichia coli and Klebsiella strains

The cloned poly-3-hydroxybutyrate (PHB) synthesis pathway from Alcaligenes eutrophus has been introduced into sucrose-utilizing strains of Escherichia coli, Klebsiella aerogenes, and Klebsiella oxytoca. The plasmid-borne genes were well expressed in these environments and were able to mediate the production of significant amounts of PHB when the bacteria were grown with sucrose as the sole carbon source. The molecular weight of the PHB polymer made in K. aerogenes and E. coli was approximately 1 x 10(6) to 2 x 10(6). Sucrose uptake in K. aerogenes was measured and found to be similar to that found for other Klebsiella strains, but sucrose uptake in the E. coli strain was not detectable. K. aerogenes is able to utilize sugarcane molasses as the sole carbon source to accumulate PHB at the rate of approximately 1 g of PHB per liter of culture fluid per h. A K. oxytoca fadR strain was able to incorporate 3-hydroxyvalerate into a poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-V) polymer to levels as high as 56 mol% when grown in a medium containing propionate. Total PHB-co-V levels could be enhanced by adding propionate at the beginning of stationary phase rather than at the time of inoculation.

Aspects of immunity for the AMA-1 family of molecules in humans and non-human primates malarias

The apical membrane antigen (AMA-1) family of malaria merozoite proteins is characterised by a high degree of inter-species conservation. Evidence that the protein (PK66/AMA-1) from the simian parasite Plasmodium knowlesi was protective in rhesus monkeys suggested that the 83kDa P. falciparum equivalent (PF83/AMA-1) should be investigated for protective effects in humans. Here we briefly review pertinent comparative data, and describe the use of an eukaryotic full length recombinant PF83/AMA-1 molecule to develop a sensitive ELISA for the determination of serological responses in endemic populations. The assay has revealed surprisingly high levels of humoral response to this quantitatively minor antigen. We also show that PK66/AMA-1 inhibitory mAb's are active against merozoites subsequent to release from schizont-infected red cells, further implicating AMA-1 molecules in red cell invasion.

Active site labeling of HIV-1 reverse transcriptase

The human immunodeficiency virus-1 reverse transcriptase (HIV-1 RT) heterodimer (M(r) = 66,000 and M(r) = 51,000) has been photoaffinity labeled using 4-thiodeoxyuridine triphosphate (S4-dUTP) as a probe. A nascent polymerization complex was assembled from a single-stranded DNA template, a 12-mer DNA primer, and the necessary dNTPs (one of which was alpha-32P-labeled) to extend the primer to produce the n-1 product. The photoaffinity probe was then uniquely added at the 3'-terminal position of the extended primer bound at the catalytic site and photolyzed. The larger subunit (p66) was exclusively derivatized. The unique radioactive peptide resulting from proteolysis was isolated and identified by amino acid sequencing.

Wheat germ and yeast RNA polymerase II: photoaffinity labeling by 4-thiouracil 5'-monophosphate positioned uniquely at the 3' end of an enzyme-bound [32P]-containing transcript

A stable ternary transcription complex was formed with either wheat germ or yeast RNA polymerase II using a ribotrinucleotide primer (GpCpG) to initiate transcription on a short synthetic single-strand DNA template. The template was designed to limit the incorporation of a photoprobe S4-UMP (4-thio-UMP) to a unique position at the 3' terminus of the transcript. The resulting stable ternary transcription complex was photolyzed to cross-link the bound transcript ([32P]-labeled by the incorporation of [alpha-32P]CMP) with the protein domain at or near the active site. Separation of the protein components by electrophoresis in polyacrylamide gel containing SDS and analysis by autoradiography and silver staining revealed that for either enzyme only the largest subunit was [32P] labeled.

Polyhydroxyalkanoate production in recombinant Escherichia coli

The bacterial species Escherichia coli has proven to be a powerful tool in the molecular analysis of polyhydroxyalkanoate (PHA) biosynthesis. In addition, E. coli holds promise as a source for economical PHA production. Using this microorganism, clones have been developed in our laboratory which direct the synthesis of poly-beta-hydroxybutyrate (PHB) to levels as high as 95% of the cell dry weight. These clones have been further enhanced by the addition of a genetically mediated lysis system that allows the PHB granules to be released gently and efficiently. This paper describes these developments, as well as the use of an E. coli strain to produce the copolymer poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-3HV).

Production of poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) in a recombinant Escherichia coli strain

An Escherichia coli strain has been constructed that produces the copolymer poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) P(HB-co-HV). This has been accomplished by placing the PHB biosynthetic genes from Alcaligenes eutrophus into an E. coli fadR atoC(Con) mutant and culturing the strain in M9 minimal medium containing glucose and propionate. 3-Hydroxyvalerate incorporation is absolutely dependent on the presence of both glucose and propionate, and 3-hydroxybutyrate-3-hydroxyvalerate ratios in the copolymer can be manipulated by altering the propionate concentration and/or the glucose concentration in the culture. P(HB-co-HV) production can be accomplished by using a wide variety of feeding regimens, but the most efficient is to allow the culture to grow to late log phase in minimal medium containing acetate and then add glucose and propionate to initiate copolymer production. A broad range of propionate concentrations can be used in the culture to stimulate 3-hydroxyvalerate incorporation; however, the most efficient utilization of propionate occurs at concentrations below 10 mM. 3-Hydroxyvalerate molar percentages in the copolymer are relatively constant over the course of growth. The copolymer has been purified and confirmed to be P(HB-co-HV) by gas chromatography/mass spectrometry and differential scanning calorimetry.

Evidence of spare A1-adenosine receptors in guinea pig atrioventricular node

In normoxic, isolated perfused guinea pig hearts instrumented for measurement of atrioventricular nodal conduction time (AVCT), an analysis utilizing the irreversible A1-adenosine (Ado) antagonist, meta-1,3-phenylene diisothiocyanate xanthine amine cogener (m-DITC-XAC), a novel isothiocyanate derivative of 1,3-dialkylxanthine, was used to investigate whether spare A1-Ado receptors exist in the guinea pig atrioventricular (AV) node and the degree of amplification (reserve) between A1-Ado receptor occupancy and dromotropic response (e.g., AVCT slowing). The potency, dose dependency, and kinetic profile (time dependence of washout and washin) of m-DITC-XAC was determined and compared with those of known competitive (reversible) A1-Ado receptor antagonists. In the presence of m-DITC-XAC, Ado and N6-cyclopentyladenosine (CPA) produced submaximal dromotropic responses. In a series of 19 hearts, m-DITC-XAC caused 100% apparent antagonism of the effect of Ado on AVCT even after 60 min of washout. In contrast, greater than 90% of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and XAC-induced antagonism of the effect of Ado on AVCT dissipated within 35 min. Unlike XAC, which caused maximal attenuation of Ado's AVCT effect within 5 min and remained constant thereafter, m-DITC-XAC showed marked time- and concentration-dependent behavior. It was found that 5 min of 0.5 microM m-DITC-XAC pretreatment irreversibly inactivated 72% of the A1-Ado receptors mediating the dromotropic effect, and the estimated agonist equilibrium dissociation constant for CPA was 84 +/- 4 nM. The percent of spare A1-Ado receptors at the EC50 and extrapolated maximal S-H interval prolongation levels was 20 and 54%, respectively, and the reserve (coupling amplification) varied from 1 to 2.3 within the 0-50% maximal response range. In summary, m-DITC-XAC appears to specifically and irreversibly antagonize the negative dromotropic effect of Ado and CPA, and guinea pig AV nodal tissue possesses spare A1-Ado receptors.

Open versus laparoscopic cholecystectomy: an initial analysis

Laparoscopic cholecystectomy is a new procedure in the armamentarium of the general surgeon. Its utility was investigated by comparison to open cholecystectomy in terms of procedure time, complications, hospital stay, and total hospital cost. Procedure time was approximately 200% longer with a higher incidence of intraoperative stone and bile spillage (17%) in the laparoscopic group. Hospital stay was reduced by 60% using the laparoscopic technique. No difference in total hospital cost existed between the two groups. The learning curve had an affect on hospital costs, which will decrease as more experience is gained with this procedure. Although laparoscopic cholecystectomy, at least initially, has no cost advantage over open cholecystectomy, laparoscopic cholecystectomy may be preferred by patients seeking shorter hospital stays and presumably shorter total recovery time.

The morbidity, mortality, and economic costs of cigarette smoking in New Hampshire

The Surgeon General of the United States Public Health Service has identified cigarette smoking as the single most important source of preventable morbidity and premature mortality. An analysis was conducted in the state of New Hampshire to determine the consequences of smoking: morbidity, mortality, and economic costs to the population. Data were collected on smoking prevalence, smoking attributed deaths, years of potential life lost, hospital days attributed to smoking diagnoses, direct medical costs, and per capita incomes. Smoking attributable fractions were applied to these data. In 1983, 16% of total statewide deaths were attributable to cigarette smoking. These deaths included 15% of the cardiovascular deaths, 20% of cancer deaths, 42% of respiratory disease deaths, 3% of digestive disease deaths, and 5% of infant deaths, in a population of less than 1 million. These deaths represented almost 3100 years of potential life lost. Smoking attributable hospital days totaled almost 70,000, for 8% of male and 4% of female hospital days. Direct medical care costs attributable to cigarette smoking were over $76 million, 7% of the total statewide medical costs. Indirect costs (present value of lost earnings due to premature mortality and morbidity attributable to smoking) were almost $118 million. These economic costs totaled almost $200 million. The results of this study were used extensively by the New Hampshire media and volunteer agencies. This methodology can be a model for other local area analyses.

Yeast RNA polymerase I. Derivatization of the 190 and 135 subunits by 4-thiouridine monophosphate positioned uniquely at the 3' terminus of an enzyme-bound 32P-containing transcript initiated by a triribonucleotide primer on synthetic single-stranded DNA

Specific transcription complexes were formed with yeast RNA polymerase I using a cognate oligoribotri-nucleotide primer (GCG) to initiate transcription on short synthetic single-stranded DNA templates. The templates were designed to limit the incorporation of a photoprobe, 4-thiouridine triphosphate, to a single unique position at the 3' terminus of the product RNA (position 12, 13, 14, or 15). The resulting transcription complexes were photolyzed to cross-link the bound transcript (radiolabeled with [alpha-32P]CTP) to the protein with the probe located at the catalytic site. Separation of the protein subunit components by 5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and analysis by autoradiography and silver staining revealed that the two largest subunits (A190 and A135) were radiolabeled. The ratio of subunit labeling (A190/A135) decreased as the RNA transcript increased from 12 to 15 nucleotides in length. This decrease in ratio resulted from a progressive reduction of A190 subunit labeling while the A135 subunit derivatization remained essentially constant. It was also observed that the DNA template was radiolabeled.