Greenhouse gas footprinting for small businesses--the use of input-output data.

To mitigate anthropogenic climate change greenhouse gas emissions (GHG) must be reduced; their major source is man's use of energy. A key way to manage emissions is for the energy consumer to understand their impact and the consequences of changing their activities. This paper addresses the challenge of delivering relevant, practical and reliable greenhouse gas 'footprint' information for small and medium sized businesses. The tool we describe is capable of ascribing parts of the total footprint to specific actions to which the business can relate and is sensitive enough to reflect the consequences of change. It provides a comprehensive description of all emissions for each business and sets them in the context of local, national and global statistics. It includes the GHG costs of all goods and services irrespective of their origin and without double accounting. We describe the development and use of the tool, which draws upon both national input-output data and process-based life cycle analysis techniques; a hybrid model. The use of national data sets the output in context and makes the results consistent with national and global targets, while the life cycle techniques provide a means of reflecting the dynamics of actions. The model is described in some detail along with a rationale and a short discussion of validity. As the tool is designed for small commercial users, we have taken care to combine rigour with practicality; parameterising from readily available client data whilst being clear about uncertainties. As an additional incentive, we also report on the potential costs or savings of switching activities. For users to benefit from the tool, they need to understand the output and know how much confidence they should place in the results. We not only describe an application of non-parametric statistics to generate confidence intervals, but also offer users the option of and guidance on adjusting figures to examine the sensitivity of the model to its components. It is important that the user does not see the model as a calculator that will generate one truth, but as a method of gaining insight and informing management decisions. We describe its application in tourism businesses in North West England as a demonstrator for the service sector remote from simple primary production, with brief case studies. We discuss its success compared to traditional approaches and outline further development work.

Transient first-degree atrioventricular block following intercostal nerve block for vascular ring repair.

Transient first-degree heart block developed following surgery to divide a vascular ring. This unusual complication was related to autonomic impairment secondary to a local nerve block. The role of the autonomic innervation of the atrioventricular node and the potential role of the local anesthetic are reviewed.

Differential removal of thymidine nucleotide analogues from blocked DNA chains by human immunodeficiency virus reverse transcriptase in the presence of physiological concentrations of 2'-deoxynucleoside triphosphates.

Removal of 2',3'-didehydro-3'-deoxythymidine-5'-monophosphate (d4TMP) from a blocked DNA chain can occur through transfer of the chain-terminating residue to a nucleotide acceptor by human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). ATP-dependent removal of either d4TMP or 3'-azido-3'-deoxythymidine-5'-monophosphate (AZTMP) is increased in AZT resistant HIV-1 RT (containing D67N/K70R/T215F/K219Q mutations). Removal of d4TMP is strongly inhibited by the next complementary deoxynucleoside triphosphate (50% inhibitory concentration [IC(50)] of approximately 0.5 microM), whereas removal of AZTMP is much less sensitive to this inhibition (IC(50) of >100 microM). This could explain the lack of cross-resistance by AZT-resistant HIV-1 to d4T in phenotypic drug susceptibility assays.

Early results of isoelastic hemiarthroplasty in chronic shoulder arthritis.

Fourteen isoelastic shoulder hemiarthroplasties were studied in patients with shoulder pain due to chronic rheumatoid arthritis and osteoarthritis unresponsive to conservative means. The average follow-up was 27 months (range: 12-46 months) and the average patient age was 66.4 years (range: 54-79 years). A Constant shoulder score was used to assess results. Pain relief was obtained in 85.7% of patients. Function scores averaged 8 preoperatively and 13 postoperatively. Subjectively, 12 patients improved. Average gain was 33 degrees of abduction, 35 degrees of flexion, and 21 degrees of external rotation. Internal rotation improved by two levels on the spine. Total shoulder scores improved from an average of 42 points preoperatively to 78 points postoperatively. There was 1 complication of immediate postoperative dislocation. Early results with isoelastic (polyacetyl resin) shoulder hemiarthroplasty are encouraging. The prosthesis is inexpensive and easy to use, requires minimal bone resection, involves cementless fixation, and has established results in tumor surgery. Its long-term value for chronic arthritis will be reported as part of an ongoing prospective study.

A mechanism of AZT resistance: an increase in nucleotide-dependent primer unblocking by mutant HIV-1 reverse transcriptase.

Mutations in HIV-1 reverse transcriptase (RT) give rise to 3'-azido-3'-deoxythymidine (AZT) resistance by a mechanism that has not been previously reproduced in vitro. We show that mutant RT has increased ability to remove AZTMP from blocked primers through a nucleotide-dependent reaction, producing dinucleoside polyphosphate and extendible primer. In the presence of physiological concentrations of ATP, mutant RT extended 12% to 15% of primers past multiple AZTMP termination sites versus less than 0.5% for wild type. Although mutant RT also unblocked ddAMP-terminated primers more efficiently than wild-type RT, the removal of ddAMP was effectively inhibited by the next complementary dNTP (IC50 approximately equal to 12 microM). In contrast, the removal of AZTMP was not inhibited by dNTPs except at nonphysiological concentrations (IC50 > 200 microM).

Heart rate variability in healthy children and in those with congenital heart disease both before and after operation.

There are no reports of standard measures of heart rate variability (HRV) in pediatric patients with heart disease. Time domain (standard deviation of all normal RR intervals [SDNN], standard deviation of all 5-minute mean RR intervals, average standard deviation of all 5-minute RR intervals, and frequency domain (total, low- [LF], and high-frequency [HF] power) measures of HRV were (1) obtained in 45 healthy children, (2) compared between 36 children with congenital heart disease and age-matched controls, (3) compared before and after surgery, and (4) compared between age-matched postoperative patients staying <7 days (group I, n = 16) and those staying longer (group II, n = 16). In healthy children, SDNN increased rapidly during infancy and more gradually thereafter, while the LH/HF ratio decreased until preschool age, with a later increase into adolescence. Compared with controls, preoperative patients had decreased total (53 +/- 55 vs 84 +/- 75 beats/min2/Hz, p = 0.01) and HF (12 +/- 14 vs 29 +/- 46 beats/min2/Hz, p = 0.03) power despite having similar heart rates. In the immediate postoperative period, all measures of HRV were decreased from preoperative values. Groups I and II did not differ in mean RR interval or HRV preoperatively; however, postoperatively, HRV was decreased in group II when compared with group I (SDNN 53 +/- 17 vs 40 +/- 14 ms, p = 0.01), although the mean RR interval remained comparable (499 +/- 81 vs 481 +/- 62 ms, p = 0.3). It is concluded that (1) there are significant age-related changes in HRV in healthy children, (2) preoperatively, children with congenital heart disease have reduced total and HF power when compared with healthy controls, (3) HRV is further reduced postoperatively in all patients, and (4) prolonged postoperative hospitalization is associated with a greater reduction in HRV.

Unblocking of chain-terminated primer by HIV-1 reverse transcriptase through a nucleotide-dependent mechanism.

HIV-1 replication is inhibited by the incorporation of chain-terminating nucleotides at the 3' end of the growing DNA chain. Here we show a nucleotide-dependent reaction catalyzed by HIV-1 reverse transcriptase that can efficiently remove the chain-terminating residue, yielding an extendible primer terminus. Radioactively labeled 3'-terminal residue from the primer can be transferred into a product that is resistant to calf intestinal alkaline phosphatase and sensitive to cleavage by snake venom phosphodiesterase. The products formed from different nucleotide substrates have unique electrophoretic migrations and have been identified as dinucleoside tri- or tetraphosphates. The reaction is inhibited by dNTPs that are complementary to the next position on the template (Ki approximately 5 microM), suggesting competition between dinucleoside polyphosphate synthesis and DNA polymerization. Dinucleoside polyphosphate synthesis was inhibited by an HIV-1 specific non-nucleoside inhibitor and was absent in mutant HIV-1 reverse transcriptase deficient in polymerase activity, indicating that this activity requires a functional polymerase active site. We suggest that dinucleoside polyphosphate synthesis occurs by transfer of the 3' nucleotide from the primer to the pyrophosphate moiety in the nucleoside di- or triphosphate substrate through a mechanism analogous to pyrophosphorolysis. Unlike pyrophosphorolysis, however, the reaction is nucleotide-dependent, is resistant to pyrophosphatase, and produces dinucleoside polyphosphates. Because it occurs at physiological concentrations of ribonucleoside triphosphates, this reaction may determine the in vivo activity of many nucleoside antiretroviral drugs.

Monitoring plasma HIV-1 RNA levels in addition to CD4+ lymphocyte count improves assessment of antiretroviral therapeutic response. ACTG 241 Protocol Virology Substudy Team.

BACKGROUND: CD4+ lymphocyte counts and plasma HIV-1 RNA levels predict progression of HIV-related disease, but the relative importance of these and other virological factors in defining response to antiretroviral therapy is not yet clear. OBJECTIVE: To determine the short-term variability of plasma HIV-1 RNA level during stable therapy; the relative importance of pretreatment values and early changes in CD4+ count, HIV-1 RNA levels, and infectious HIV-1 titers in mononuclear cells of peripheral blood and pretreatment syncytium-inducing phenotype of an HIV-1 isolate for prediction of disease progression and decline in CD4+ counts during therapy. DESIGN: Data were collected prospectively in a randomized, clinical trial comparing two combination regimens (ACTG [AIDS Clinical Trials Group] Protocol 241) and pooled across treatments. SETTING: 8 AIDS Clinical Trials Units. PATIENTS: 198 adults with HIV-1 infection and no more than 350 CD4+ lymphocytes/mm3 who had received at least 6 months of nucleoside therapy. INTERVENTIONS: All patients received zidovudine and didanosine; 100 received nevirapine and 98 received placebo. MEASUREMENTS: CD4+ lymphocyte counts, plasma HIV-1 RNA levels, and infectious HIV-1 titers in cells were measured before and 8 and 48 weeks after study treatment. Assay for the syncytium-inducing viral phenotype was done at baseline. Progression was defined as occurrence of opportunistic infection, malignancy, or death during the 48 weeks after treatment began. RESULTS: The difference between two measurements of HIV-1 RNA levels at baseline was within +/-0.39 log10 copies/mL (2.5-fold) for 90% of 167 patients receiving stable therapy. In a multivariate model, risk for disease progression was reduced by 56% (95% CI, 8% to 79% [P = 0.028]) for every 10-fold lower HIV-1 RNA level at baseline, by 52% (CI, 6% increase to 79% reduction [P = 0.071]) for every 10-fold reduction in HIV-1 RNA level at 8 weeks after treatment initiation, and by 67% (CI, 42% to 81% [P < 0.001]) for every 2-fold higher CD4+ count at baseline. These risk factors and syncytium-inducing viral phenotype at baseline, but not infectious HIV-1 titers in circulating cells, were associated with change in CD4+ counts over 48 weeks. CONCLUSIONS: For an individual patient, a change in plasma HIV-1 RNA level of 2.5-fold or more probably indicates a true biological change. Monitoring HIV-1 RNA levels and CD4+ lymphocytes before a change in antiretroviral treatment and monitoring HIV-1 RNA levels shortly thereafter improves prediction of disease progression and decline in CD4+ counts for 1 year compared with monitoring CD4+ counts of HIV-1 RNA levels alone. Additional monitoring of infectious HIV-1 titers in mononuclear cells of peripheral blood is not useful.

Ulnar dimelia. Is it a true duplication of the ulna?

Ulnar dimelia (mirror hand) is a rare congenital disorder, characterized by duplication of the ulna, absence of the radius and polydactyly. Approximately 60 cases have been reported worldwide. We present a new case, with its own distinguishing features. These features illustrate that the aetiology of ulnar dimelia is probably failure of differentiation of a part of the ray rather than its pure duplication.

Arterial oxygenation during one-lung ventilation. A comparison of enflurane and isoflurane.

BACKGROUND: Because maintaining arterial oxygenation (PaO2) during one-lung ventilation (OLV) can be a clinical problem, it is useful to be aware of factors that influence PaO2 in this situation and are under the control of the anesthesiologist. It is unknown whether, among the commonly used volatile anesthetic agents, one is associated with higher PaO2 levels. Clinical studies suggest that isoflurane provides superior PaO2 during OLV than does halothane. These have not been compared to enflurane. The authors studied PaO2 and hemodynamics during OLV with 1 MAC enflurane versus 1 MAC isoflurane. METHODS: Twenty-eight adults who had prolonged periods of OLV anesthesia with minimal trauma to the nonventilated lung (thoracoscopic or esophageal surgery) were studied in a cross-over design. Patients were randomized to two groups: Group 1 received 1 MAC enflurane in oxygen from induction until after the first 30 min of OLV, then were switched to 1 MAC isoflurane. In group 2, the order of the anesthetics was reversed. RESULTS: Isoflurane was associated with higher PaO2 values during OLV (P < 0.0001). Mean PaO2 (+/- SD) after 30 min OLV isoflurane was 231 (+/- 125) mmHg versus 184 (+/- 106) mmHg after 30 min OLV enflurane. The difference in PaO2 between the two anesthetics was most marked in the patients with the highest PaO2 during OLV: PaO2 isoflurane PaO2 enflurane varies; is directly proportional to PaO2 isoflurane (r = 0.65, P < 0.001). There were no other significant differences between anesthetic gases in the measured hemodynamic or respiratory variables. In the subgroup of patients with pulmonary artery catheters (n = 7), PaO2 correlated with cardiac output during OLV for both anesthetics (r = 0.81, P < 0.001). CONCLUSIONS: During OLV, the PaO2 values with 1 MAC isoflurane were greater than those with enflurane. The dependence of PaO2 on cardiac output does not support the hypothesis that an increase in cardiac output will cause a decrease in hypoxic pulmonary vasoconstriction and a decrease in PaO2 during OLV.

Echocardiographic diagnosis of discontinuous left pulmonary artery as an isolated lesion.

The diagnosis of a discontinuous left pulmonary artery arising from a left ductus arteriosus was made by two-dimensional and Doppler echocardiography in an infant with recurrent pneumonia. The diagnosis was later confirmed at cardiac catheterization and surgery. The suprasternal notch views were especially useful for the identification of the left pulmonary artery. In this patient with a right aortic arch, the left pulmonary artery was supplied by a left ductus arteriosus that arose from the innominate artery. This case report describes the echocardiographic diagnosis of discontinuous left pulmonary artery as an isolated lesion, an unusual lesion that can easily be missed. It emphasizes the necessity of a careful and complete examination with particular emphasis on pulmonary artery continuity in patients suspected of having congenital heart disease or respiratory compromise as a result of a cardiovascular cause.

Sedation for upper gastrointestinal endoscopy: a comparison of alfentanil-midazolam and meperidine-diazepam.

The authors studied the efficacy and cost of substituting sedation using midazolam and alfentanil for the existing regimen of diazepam and meperidine in patients requiring upper gastrointestinal endoscopy. Sixty consenting subjects were randomized to receive either meperidine 50 mg with diazepam approximately 90 micrograms.kg-1 (Group D) or alfentanil 250 micrograms with midazolam approximately 50 micrograms.kg-1 (Group M). Endoscope insertion time, patient acceptance, apnoeic or desaturation episodes were noted by a physician observer. Pulse oximetry was used to monitor heart rate and oxygen saturation (SpO2) during endoscopy. Subjects performed four-choice reaction time (4CRT) tests before, 30 and 60 min after endoscopy, and were assessed for nausea or dizziness and their ability to stand and walk. During endoscopy, insertion time was shorter (84 +/- 45 sec vs 122 +/- 83 sec, P < 0.03) and fewer aversive movements occurred (0.4 +/- 0.6 vs. 1.7 +/- 2.4, P < 0.005) in Group M than Group D. No subject in either group suffered any apnoea or prolonged desaturation requiring supplemental oxygen. Irrespective of treatment group, greater decreases in SpO2 (6.1 +/- 3.4% vs 3.6 +/- 2.2% P < 0.001) occurred in subjects > 45 yr of age than in subjects < or = 45 yr. During recovery 4CRT values at 30 min after endoscopy were longer (723 +/- 226 msec vs 594 +/- 139 msec, P < 0.005) in Group M than in Group D but not after 60 min. It was concluded that the small differences in endoscopy conditions and greater sedation during the first 30 min of recovery did not justify the additional cost of using midazolam and alfentnil.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of temporary atrial pacing leads.

Thirty-five patients were randomized to receive either the Medtronic 6500 or one of two braided multifilament temporary pacing leads in the atrium following open heart surgery. Sensing performance was judged by amplitude, slew rate, and the proportion of patients with an adequate sensing threshold. Pacing performance was assessed with measures of impedance, threshold voltage, current, and energy. The Medtronic 6500 demonstrated superior sensing and lower energy consumption compared to braided multifilament leads. This type of lead may offer advantages when using atrial synchronous temporary pacing systems.

Quantitative analysis of human immunodeficiency virus type 1 antibody reactivity by western immunoblots: evaluation of relative antibody levels in seropositive individuals and mothers.

A quantitative analysis of antibody responses to human immunodeficiency virus type 1 (HIV-1) proteins using Western immunoblots and 125I-labeled protein A is reproducible and can be validated. The antibody levels obtained by Western immunoblots were compared with stoichiometric p24 radioimmunoassay over a wide range of antibody (correlation coefficient, .94; P less than .001). Antibody levels to gp160 and gp120 were validated using purified antigens. Analysis of antibody levels from 31 seropositive individuals revealed a statistically significant correlation between antibody levels to p24 and the other viral proteins except gp120. Anti-gag p24 antibody was strongly correlated with antibodies to other env products, specifically gp41 and gp160. Using the validated assay, HIV-1-infected mothers of infants were found to have highly variable levels of antibody to all viral proteins. Mothers of infected infants did not differ significantly from mothers of uninfected infants in antibody pattern or levels to any viral protein including gp120.

Acoustic analysis of the closing sounds of bileaflet prosthetic valves in a sheep model.

Previous investigations of mechanical valve sounds have shown that (1) frequency spectra of sounds produced by abnormal valves differ from those of properly functioning valves and (2) leaflets of normally functioning bileaflet valves do not close synchronously. This investigation studied effects of mechanical valve size, environment, and hemodynamic state on closing sounds. A single 25 mm bileaflet mitral mechanical valve was implanted in six sheep and a single 27 mm valve in four sheep. With digital signal processing, asynchronous leaflet closure and frequency spectra were assessed after alterations in animal position, respiratory phase, heart rate, afterload, contractility, and preload. Both asynchronous leaflet closure and frequency spectra varied among animals, and, except for a decrease in asynchrony with increasing contractility, were largely independent of valve size and hemodynamics. Baseline asynchrony ranged from 0.5 to 4.2 msec. Frequency spectra were characterized by the first three resonant peaks. Lowest resonant peaks ranged from 2.5 to 3.4 kHz, middle from 4.7 to 6.8 kHz, and highest from 7.2 to 9.6 kHz. These results indicate that accurate assessment of mechanical valve function with acoustic analysis requires baseline studies in all patients by means of a system with a frequency response of more than 10 kHz.

Heat loss in an animal experimental model.

Heat loss leading to hypothermia is common during surgery, particularly when a body cavity is exposed. To determine the principal site of heat loss we used heat flux transducers to measure heat loss from the skin and the exposed abdominal cavity of seven pigs. Heat loss from the skin was 74 +/- 15 W/m2, and from the abdominal cavity, 350 +/- 122 W/m2 (p less than 0.002; ratio = 1:4.7). The area of the skin was 0.52 +/- 0.06 m2, and of the abdominal cavity, 0.04 +/- 0.006 m2 (ratio = 13.6:1). For every 13.6 watts lost from the skin, 4.7 watts were lost from the abdominal cavity; i.e. skin heat loss accounted for 74% of total heat loss. Therefore adequate insulation would reduce the incidence of hypothermia. Evaporation accounted for the largest heat loss from the abdominal cavity. Evaporative losses could be minimised by enclosing the bowel in a plastic bag.

Heat loss in exposed volunteers.

Hypothermia is a common complication of major surgery and trauma. We studied this problem using Heat Flux Transducers to directly measure heat exchange between seven exposed volunteers and the environment. Heat exchange by radiation and convection was measured from the anterior chest wall and by conduction, between the back and a thermal mattress (CSZ, Blanketrol II). We determined the coefficients for: radiation = 6.6; convection = 8.3 square root of v; combined radiation and convection = 9.7; conductance = 41, all expressed in W/m2.degrees C. The clinical significance of these results is that heat loss, by radiation and convection alone, is 10 W/m2.degrees C. However, heat production under anaesthesia is only 40 W/m2, so a temperature gradient of greater than 4 degrees C between the skin and environment will cause more heat to be lost than is produced. The thermal mattress can supply 41 W/m2.degrees C, effectively doubling heat production.

Transcatheter electrical ablation of accessory pathways in children.

Supraventricular tachycardia (SVT), the most common sustained symptomatic arrhythmia of childhood, is often supported by a manifest or concealed accessory pathway. Permanent interruption of the accessory pathway usually requires surgical division. Recent experience with electrical ablation of posterior septal pathways in adults prompted us to apply the technique to children. Six children, ages 8 to 15 years, underwent a complete electrophysiological study followed by transcatheter electrical ablation. Five of the 6 children, 3 with a right posterior septal and 2 with a left posterior septal pathway, were approached with the ablation catheter at the os of the coronary sinus. In the remaining patient, a left lateral pathway was mapped with an electrode catheter in the coronary sinus and then approached with the ablation catheter through the patent foramen into the left atrium. Two patients are asymptomatic 18-24 months postablation; one patient had return of anomalous conduction between 7 and 21 days after ablation. Two patients had transient interruption of anomalous conduction, whereas one patient experienced no effect. We conclude that in carefully selected patients, transcatheter electrical ablation offers an alternative to surgery for permanent interruption of an accessory pathway.

Epitopes on the major capsid protein of simian virus 40.

Thirteen monoclonal antibodies which react with the major capsid protein (VP1) of simian virus 40 (SV40) have been isolated. Of these, five neutralized viral infectivity when added in sufficient concentration. Seven of the antibodies reacted with denatured VP1 and also recognized fragments generated by protease or cyanogen bromide cleavage. The region of VP1 recognized by all seven antibodies was mapped within a nine-amino-acid segment located in the carboxyl portion of the protein (from amino acid positions 312 to 321). This region is likely to protrude from the surface of the protein as judged by high hydrophilicity and low hydropathy predicted from the amino acid sequence and lack of secondary structure by contrast with the rest of the protein for which predominantly beta-sheet structure is predicted. Competition between these antibodies and synthetic peptides for binding to virus particles confirmed that the continuous epitope is contained within the nine-amino-acid sequence. Competition between the different monoclonal antibodies suggested that the continuous epitope was also part of more complex discontinuous epitopes recognized by some of the other antibodies. These results support a model in which a segment of the carboxyl-terminal portion of VP1 protrudes from the surface of the virus to form an antigenic structure.