Within-population Y-linked genetic variation for lifespan in Drosophila melanogaster.

The view that the Y chromosome is of little importance for phenotypic evolution stems from early studies of Drosophila melanogaster. This species' Y chromosome contains only 13 protein-coding genes, is almost entirely heterochromatic and is not necessary for male viability. Population genetic theory further suggests that non-neutral variation can only be maintained at the Y chromosome under special circumstances. Yet, recent studies suggest that the D. melanogaster Y chromosome trans-regulates hundreds to thousands of X and autosomal genes. This finding suggests that the Y chromosome may play a far more active role in adaptive evolution than has previously been assumed. To evaluate the potential for the Y chromosome to contribute to phenotypic evolution from standing genetic variation, we test for Y-linked variation in lifespan within a population of D. melanogaster. Assessing variation for lifespan provides a powerful test because lifespan (i) shows sexual dimorphism, which the Y is primarily predicted to contribute to, (ii) is influenced by many genes, which provides the Y with many potential regulatory targets and (iii) is sensitive to heterochromatin remodelling, a mechanism through which the Y chromosome is believed to regulate gene expression. Our results show a small but significant effect of the Y chromosome and thus suggest that the Y chromosome has the potential to respond to selection from standing genetic variation. Despite its small effect size, Y-linked variation may still be important, in particular when evolution of sexual dimorphism is genetically constrained elsewhere in the genome.

DDT resistance, epistasis and male fitness in flies.

In Drosophila melanogaster, the DDT resistance allele (DDT-R) is beneficial in the presence of DDT. Interestingly, DDT-R also elevates female fitness in the absence of DDT and existed in populations before DDT use. However, DDT-R did not spread regardless of DDT-independent selective advantages in females. We ask whether sexual antagonism could explain why DDT-R did not spread before pesticide use. We tested pre- and post-copulatory male fitness correlates in two genetic backgrounds into which we backcrossed the DDT-R allele. We found costs to DDT-R that depended on the genetic background in which DDT-R was found and documented strong epistasis between genetic background and DDT-R that influenced male size. Although it remains unclear whether DDT-R is generally sexually antagonistic, or whether the fitness costs noted would be sufficient to retard the spread of DDT-R in the absence of DDT, general fitness advantages to DDT-R in the absence of DDT may be unlikely.

Non-invasive positive pressure ventilation for severe thoracic trauma.

A 35-year-old man was admitted to the intensive care unit (ICU) following a road traffic accident. He had sustained severe trauma to the left side of his chest, as well as other musculoskeletal injuries. After a short initial period of ventilation of the lungs via a tracheal tube, he was managed using a combination of continuous positive airway pressure and non-invasive positive pressure ventilation. He avoided ventilator-associated pneumonia, and spent a large part of his time on the ICU without any invasive monitoring lines, another potential focus of infection. He was discharged from the ICU after 25 days without having suffered any septic complications. The role of non-invasive positive pressure ventilation in severe thoracic trauma is discussed.

A carbon column-based liquid chromatography electrochemical approach to routine 8-hydroxy-2'-deoxyguanosine measurements in urine and other biologic matrices: a one-year evaluation of methods.

8-Hydroxy-2'-deoxyguanosine (8OH2'dG) is a principal stable marker of hydroxyl radical damage to DNA. It has been related to a wide variety of disorders and environmental insults, and has been proposed as a useful systematic marker of oxidative stress. Analytic procedures for 8OH2'dG in DNA digests are well established; however, routine measurement of free 8OH2'dG in other body fluids such as urine or plasma has been problematic. This has hindered its evaluation as a general clinical, therapeutic monitoring, or environmental assessment tool. Therefore, we developed a liquid chromatography electrochemical column-switching system based on the use of the unique purine selectivity of porous carbon columns that allows routine accurate measurement of 8OH2'dG in a variety of biologic matrices. This paper describes the rationale of the system design and the protocols developed for 8OH2'dG in urine, plasma, cerebrospinal fluid, tissue, DNA, saliva, sweat, kidney dialysis fluid, foods, feces, culture matrix, and microdialysates. Concentrations in both human and animal body fluids and tissues are reported. The system performance is discussed in the context of a 1-year evaluation of the methods applied to approximately 3600 samples, using internal quality control and external blind testing to determine long-term accuracy. The methods are reliable and accurate, and therefore should prove useful in assessing the role and utility of oxidative DNA damage in aging and human illness.

Is it a modacrylic fibre?

This study describes the characteristics of modacrylic fibres and includes over 80 samples (previous and current) representing 15 trade names. Fibre morphology was examined using brightfield microscopy. Signs of elongation were determined using polarised light microscopy. Fibre cross sections were also examined. The generic class of fibre was divided into sub groups using polymer composition as determined by FTIR-microscopy. Microscopically, some modacrylic fibres cannot be distinguished from acrylic fibres. Others display unusual optical and morphological features which are a strong indication of their generic class. The infrared spectra provide information about the co-monomer, termonomers added to produced dye sites, the presence of solvent residue, dyes, and additives, e.g. flame retardant material. The infrared spectra should always be recorded before and after any thin layer chromatographic examination of the dye, otherwise peaks attributable to dyes, which may be a valuable comparative feature in casework will be lost.

A target fibre study on seats in public houses.

A target fibre survey was conducted to assess the random occurrence of a blue wool fibre on seats in public houses throughout the United Kingdom. Fibre tape lifts were taken from 80 seats. Four seats yielded matching fibres and five of these were found on one seat. A total of 292 fibres were identified; nine fibres proved indistinguishable from the target after comparison microscopy, microspectro-photometry and attempts at thin layer chromatography, and two of these fibres were still apparently indistinguishable after TLC analysis although only one dye component was visible.

Characteristic dye absorption peaks found in the FTIR spectra of coloured acrylic fibres.

The improved quality of spectra recorded using FTIR-microspectroscopy has meant that a lot more information is now obtainable from the spectra of dyed acrylic fibres. In addition to the main absorptions produced by the polymer material, additional absorptions resulting from the fibre dye are often present. An attempt has been made to explain some of the strongest and most frequently seen dye bands with the aid of spectra obtained from fibres treated with known dyes. Provided the dye concentration in the fibre is sufficient, it is possible to make some general observations on the type of dyes which have been used. Further investigation in conjunction with HPLC or FTIR-Raman spectroscopy would be useful.

An overview of the scientific examinations performed after an explosion on the Shankill Road.

In October 1993 an explosion occurred in a busy fish shop on the Shankill Road in Belfast resulting in the deaths of ten people and multiple casualties. Examinations were carried out by forensic scientists at the scene and in the laboratory to determine the cause of the explosion and to establish evidence of contact between the suspects and the incident.

An improved method for the preparation of combs for use in hair combing kits.

Hair combing kits are used to collect samples of fallen hair, fibres and other trace evidence from the hair of the suspect and injured party. The time taken to prepare the hair combing kits has been significantly reduced by using the comb loader described in this paper.

Prolonged use of isoflurane in a patient with tetanus.

We describe a patient with tetanus, who received isoflurane for sedation to facilitate controlled mechanical ventilation. Isoflurane was administered for 34 days, resulting in a sustained serum inorganic fluoride ion concentration in excess of 50 mumol litre-1 and a peak serum inorganic fluoride ion concentration of 87 mumol litre-1. Although these concentrations are potentially nephrotoxic, no toxicity was evident clinically.

Aspiration pneumonia and the laryngeal mask airway.

A case of aspiration pneumonia is reported after the use of a laryngeal mask airway in a young woman undergoing an elective cholecystectomy. The case illustrates the hazards of regurgitation with the laryngeal mask airway and the need for further evaluation when used with controlled mechanical ventilation.

Comparison of methohexital and propofol for electroconvulsive therapy: effects on hemodynamic responses and seizure duration.

Electroconvulsive therapy can produce severe disturbances in the cardiovascular system, most commonly a transient period of hypertension. This study was designed to determine whether propofol, in comparison with methohexital, would attenuate this hypertensive response. Fifteen patients were studied during courses of six ECT administrations, each patient receiving propofol or methohexital on different occasions. Arterial pressure, heart rate, and cardiac rhythm were recorded. The induction doses were 1.08 +/- 0.03 mg.kg-1 of methohexital, and 1.60 +/- 0.04 mg.kg-1 of propofol. Systolic pressure, diastolic pressure, and heart rate were consistently lower following propofol than methohexital (P less than 0.005). The mean maximum increase over baseline systolic pressure was 2.1 +/- 2.9 mmHg with propofol, and 26.7 +/- 4.5 mmHg with methohexital (P less than 0.001). Cardiac rhythm abnormalities were infrequent, and their incidence did not differ significantly between the two induction agents (P greater than 0.3). The duration of seizures, as measured clinically, was reduced with propofol (17.9 +/- 2.5 s) in comparison with methohexital (30.9 +/- 2.8 s) (P less than 0.001). Recovery times were similar for the two agents. Since the role of seizure duration in the therapeutic efficacy of ECT remains controversial, propofol may be a useful induction agent for this procedure.

Hemodynamic effects of verapamil during fentanyl-nitrous oxide anesthesia.

The hemodynamic effects of a verapamil infusion were investigated in six dogs given fentanyl-nitrous oxide anesthesia. Verapamil, 0.2 mg/kg, was given followed by an infusion of 3, 6, and 9 micrograms/kg per minute, which produced plasma verapamil concentrations ranging from 98 to 204 ng/ml. Verapamil significantly reduced the systemic vascular resistance index and mean arterial pressure. The decrease in afterload led to an increase in cardiac index, since there was little change in myocardial contractility (LV dP/dt). Administration of calcium chloride, 20 mg/kg, did not reverse the hemodynamic effects of verapamil. The data indicate that in dogs verapamil can be given, even in high concentrations, during fentanyl-nitrous oxide anesthesia without serious adverse electrophysiologic or hemodynamic consequences.

Cardiovascular effects of a nifedipine infusion during fentanyl-nitrous oxide anesthesia in dogs.

The hemodynamic effects of a nifedipine infusion were investigated in eight dogs given fentanyl/pancuronium/nitrous oxide/oxygen anesthesia. Nifedipine (20 micrograms/kg) was given intravenously over two minutes immediately prior to each 30-minute infusion at 2 micrograms/kg/min, 4 micrograms/kg/min, and 6 micrograms/kg/min. The range of plasma nifedipine levels obtained was 52.1 to 113.7 ng/mL. The predominant hemodynamic effects were significant reductions in systemic vascular resistance (SVR) and mean aortic pressure (MAP), accompanied by a rise in cardiac index and heart rate (HR). Administration of calcium chloride (20 mg/kg) after the nifedipine infusion had no effect on SVR or MAP, but HR was significantly reduced. Serum epinephrine and norepinephrine levels increased after the infusion of nifedipine and suggested that fentanyl did not completely overcome the sympathetic response to the profound vasodilatation. The resulting tachycardia in combination with diastolic hypotension from nifedipine could have a detrimental effect on the myocardial oxygen balance.

Haemodynamic effects of diltiazem during fentanyl-nitrous oxide anaesthesia. An in vivo study in the dog.

The haemodynamic effects of diltiazem were studied in six dogs during fentanyl-nitrous oxide (in oxygen) anaesthesia. A bolus of diltiazem 300 micrograms kg-1 was given, followed by infusions at 30, 60 and 90 micrograms kg-1 min-1 which produced plasma diltiazem concentrations of 392 +/- 30, 908 +/- 54 and 1483 +/- 134 ng ml-1, respectively. Diltiazem significantly reduced systemic vascular resistance index, mean arterial pressure, heart rate and PR interval. The decrease in afterload increased cardiac index, since there was little change in myocardial contractility (LV dP/dt). Five dogs developed second degree atrioventricular (AV) block in association with the highest dose. Administration of calcium chloride 20 mg kg-1 did not reverse the haemodynamic or electrophysiological effects of diltiazem. Isoprenaline increased heart rate and restored sinus rhythm in four dogs with AV block.

Myocardial ischaemia during non-cardiac surgery. A comparison of different lead systems using computerised ST segment analysis.

Computerised ST segment analysis was used to compare the frequency of ischaemia occurring in electrocardiographic leads II, V5, CS5 and CB5. Three out of 15 patients with ischaemic heart disease developed ischaemic changes, which were evident in all four leads in each patient. A single bipolar lead may be substituted for a true V5 lead when monitoring patients at increased risk of developing myocardial ischaemia. ST segment analysis facilitates the early diagnosis of peri-operative myocardial ischaemia, which may otherwise be missed on the standard electrocardiogram.