Association of actinomycete-like bacteria with soil-feeding termites (termitidae, termitinae)

Electron microscopy of the hindgut showed that actinomycete-like bacteria were the principal microbial associates of two African species of soil-feeding termites. Elongated cuticular spines provided attachment.

Suicide methods in Europe: a gender-specific analysis of countries participating in the "European Alliance Against Depression"

OBJECTIVE

To identify the most frequent gender-specific suicide methods in Europe.

DESIGN

Proportions of seven predominant suicide methods utilised in 16 countries participating in the European Alliance Against Depression (EAAD) were reported in total and cross-nationally. Relative risk (RR) relating to suicide methods and gender was calculated. To group countries by pattern of suicide methods, hierarchical clustering was applied.

SETTING AND PARTICIPANTS

Data on suicide methods for 119,122 male and 41,338 female cases in 2000-4/5 from 16 EAAD countries, covering 52% of European population were obtained.

RESULTS

Hanging was the most prevalent suicide method among both males (54.3%) and females (35.6%). For males, hanging was followed by firearms (9.7%) and poisoning by drugs (8.6%); for females, by poisoning by drugs (24.7%) and jumping from a high place (14.5%). Only in Switzerland did hanging rank as second for males after firearms. Hanging ranked first among females in eight countries, poisoning by drugs in five and jumping from a high place in three. In all countries, males had a higher risk than females of using firearms and hanging and a lower risk of poisoning by drugs, drowning and jumping. Grouping showed that countries might be divided into five main groups among males; for females, grouping did not yield clear results.

CONCLUSIONS

Research on suicide methods could lead to the development of gender-specific intervention strategies. Nevertheless, other approaches, such as better identification and treatment of mental disorders and the improvement of toxicological aid should be put in place.

Cationic ester-containing gemini surfactants: chemical hydrolysis and biodegradation

Two cationic gemini surfactants having ester bonds between the hydrophobic tail and the cationic moiety have been synthesized. The ester bonds were either with the ester carbonyl group away from the positive charge (esterquat type arrangement) or facing the positive charge (betaine ester type arrangement). The chemical hydrolysis of the surfactants was investigated and compared with the hydrolysis of the corresponding monomeric surfactants. The betaine ester type of surfactants was found to hydrolyze much faster than the esterquat surfactants. It was also seen that above the critical micelle concentration the gemini surfactants were much more susceptible to alkaline hydrolysis than the corresponding monomeric surfactants. The biodegradation of the geminis and the monomeric surfactants were also studied. It was found that whereas the monomeric surfactants were rapidly degraded, the two gemini surfactants were more resistant to biodegradation and could not be classified as readily biodegradable. The 60% biodegradation was reached after 35-40 days. Thus, there was no correlation between rate of chemical hydrolysis and rate of biodegradation.

Adsorption of ethoxylated cationic surfactants on self-assembled monolayers of alkanethiols on gold using surface plasmon resonance detection

Adsorption of a series of ethoxylated cationic surfactants at model surfaces of alkanethiol self-assembled monolayers was studied by the surface plasmon resonance technique. Model surfaces were tailor-made by choosing alkanethiols or mixtures of alkanethiols with methyl, hydroxyl, carboxyl, and trimethylammonium groups in terminal position. The ethoxylated and quaternized cationic surfactants having from 2 to 18 oxyethylene units, showed a decrease in adsorbed amount with increasing oxyethylene chain length for both hydrophobic and hydrophilic surfaces. On a negatively charged surface, containing carboxylate groups, the surfactant with only two oxyethylene groups adsorbed strongly due to electrostatic attraction and the adsorption increased with increasing amount of surface carboxylate groups. This work shows the usefulness of self-assembled alkanethiols on gold as a tool for performing surfactant adsorption studies on surfaces with variable hydrophobicity and charge.

Self-assembled Gemini surfactant film-mediated dispersion stability

The force-distance curves of 12-2-12 and 12-4-12 Gemini quaternary ammonium bromide surfactants on mica and silica surfaces obtained by atomic force microscopy (AFM) were correlated with the structure of the adsorption layer. The critical micelle concentration was measured in the presence or absence of electrolyte. The electrolyte effect (the decrease of CMC) is significantly more pronounced for Gemini than for single-chain surfactants. The maximum compressive force, F(max), of the adsorbed surfactant aggregates was determined. On the mica surface in the presence of 0.1 M NaCl, the Gemini micelles and strong repulsive barrier appear at surfactant concentrations 0.02-0.05 mM, which is significantly lower than that for the single C(12)TAB (5-10 mM). This difference between single and Gemini surfactants can be explained by a stronger adsorption energy of Gemini surfactants. The low concentration of Gemini at which this surfactant forms the strong micellar layer on the solid/solution interface proves that Gemini aggregates (micelles) potentially act as dispersing agent in processes such as chemical mechanical polishing or collector in flotation. The AFM force-distance results obtained for the Gemini surfactants were used along with turbidity measurements to determine how adsorption of Gemini surfactants affects dispersion stability. It has been shown that Gemini (or two-chain) surfactants are more effective dispersing agents, and that in the presence of electrolyte, the silica dispersion stability at pH 4.0 can also be achieved at very low surfactant concentrations ( approximately 0.02 mM).

Lack of seasonal mood change in the Icelandic population: results of a cross-sectional study

OBJECTIVE

The prevalence of seasonal affective disorder-as measured by the Seasonal Pattern Assessment Questionnaire-has been found to be unexpectedly low among Icelanders. The aim of this cross-sectional study was to measure seasonal variations in the prevalence of anxiety and depression among Icelanders assessed with the Hospital Anxiety and Depression Questionnaire.

METHOD

Four 1, 000-person cohorts, age 20-70 years, selected at random from the Icelandic National Register, were sent the Hospital Anxiety and Depression Scale by mail in either January, April, July, or October. Only responses from the 4-week period after each mailing were considered in the subsequent analysis.

RESULTS

The mean anxiety and depression scores in winter were not higher than those in summer for either sex. There was no significant difference between winter and summer in rates of actual or borderline cases of anxiety or depression or for the two categories combined.

CONCLUSIONS

This lack of seasonality in anxiety and depression is in sharp contrast to findings from similar cross-sectional studies and may reflect the low propensity for seasonal affective disorder that has been described in the Icelandic population.

[Quality management by physicians in Iceland.]

The Icelandic Medical Association appointed a committee in 1993 with the task of recommending how to introduce the concept of Total Quality Management into the Icelandic healthcare system. The first task was to conduct a mail survey of the current status of quality assurance. Heads of departments at the five major hospitals in Iceland were contacted as well as the chairmen of all the specialist societies. The response rate was only 37%, but compensated by two ameliorating facts; responses were obtained from most of the major departments, and there was a considerable overlap between hospital departments and specialty societies as well as between subspecialty societies. The results indicate that quality assurance is an ingrained part of Icelandic hospitals, mostly in the form of standards and retrospective audits, not prospective actions. Methods used are further detailed. Outside hospitals, the Icelandic Society of Family Physicians stands out amongst the specialty societies represented, by having organized and carried out several projects in quality assurance. It is recommended that more emphasis shall be put on prospective methods, the setting of practice guidelines, outcome studies and research in quality assurance. The lack of quality assurance in specialty practice outside hospitals needs to be addressed with vigour.

The effect of aminophylline on pharmacological stress with intravenous adenosine

Myocardial perfusion imaging with adenosine pharmacological stress may be useful in patients with obstructive lung disease who are unable to exercise. However, these patients are often treated with medications containing theophylline, which is an adenosine antagonist. This study assessed the effect of aminophylline on coronary vasodilation produced by intravenous adenosine as commonly used during cardiac imaging. Changes in coronary flow velocity (measured by intracoronary Doppler catheter) heart rate, arterial pressure and changes in coronary resistance were measured during intravenous infusion of adenosine at 140 micrograms/kg/min before and after aminophylline, 6 mg/kg intravenously in 12 patients. After aminophylline infusion, the theophylline level averaged 14 +/- 1 microgram/mL. The coronary hemodynamic effects of adenosine were markedly attenuated by aminophylline. Adenosine increased coronary blood flow velocity by 192 +/- 39% at control and 78 +/- 16% after aminophylline (P < .05 v control). Adenosine produced a 63 +/- 5% decrease in coronary vascular resistance at control and 40 +/- 6% (P < .05) after aminophylline. The utility of myocardial imaging techniques using coronary vasodilation with intravenous adenosine may be reduced in patients treated with theophylline-containing preparations.

Does pharmacologic coronary flow reserve reflect vasodilator responsiveness to increased myocardial demand in humans?

OBJECTIVE

To assess the relationship between maximal pharmacologic coronary flow reserve and metabolic coronary vasodilation in nonstenotic coronary arteries.

BACKGROUND

Evaluation of the coronary microcirculation in humans during cardiac catheterization is commonly performed by assessment of coronary hemodynamics during administration of potent coronary vasodilators. However, the relationship between maximal pharmacologic vasodilation and flow increases occurring in response to increased myocardial demand has not been evaluated.

METHODS

The coronary blood flow responses to a maximally dilating dose of intracoronary adenosine or papaverine and to a standardized atrial pacing stress were assessed in 49 patients using intracoronary Doppler velocimetry. The blood flow responses to a maximally dilating dose of intracoronary adenosine and to intravenous infusion of dobutamine were determined in 13 patients.

RESULTS

The maximal pharmacologic coronary flow reserve averaged 3.2 +/- 0.1 (mean +/- SEM). The coronary blood flow velocity increased by 32 +/- 3% during atrial pacing, and the change in coronary flow velocity was correlated with the change in the mean arterial pressure x heart rate product during pacing. Regression analysis revealed no relationship between the pharmacologic coronary flow reserve and the change in coronary flow velocity during atrial pacing or the response of the flow to pacing normalized with respect to the magnitude of stress reflected by the change in rate x pressure product. The coronary blood flow velocity increased by 135 +/- 16% during dobutamine infusion. Regression analysis revealed no relationship between the pharmacologic coronary flow reserve and the change in coronary flow velocity during dobutamine infusion.

CONCLUSIONS

Knowledge of the maximal pharmacologic coronary flow reserve is an inadequate surrogate for assessment of coronary vasodilation in response to increases in myocardial metabolic demand in nonstenotic arteries.

Contrast cine left ventriculography: comparison of two pigtail catheter shapes and analysis of factors determining the final quality

Ventricular arrhythmias or inadequate opacification of the ventricular cavity during contrast-cine left ventriculography frequently interfere with evaluation of regional wall motion, ejection fraction or mitral regurgitation. In this prospective, randomized study traditional (straight) pigtail catheter was compared with a new, large loop pigtail catheter (both 6 French, large lumen) in terms of the quality of the cine left ventriculograms. Straight (Group I) and curved pigtail (Group II) groups were further subdivided randomly into a preset (13 cc per second for 3 seconds with a pressure rise time of 0.5 seconds) injection rate (Group IA, n = 46, and Group IIA, n = 48) or operator definded injection rate (Group IB, n = 49, and Group IIB, n = 45) subgroups. The ventricular tachycardia and couplets occurred at similar frequency among the groups. The curved pigtail subgroups showed significantly more frequent catheter induced mitral regurgitation. However, the opacification and overall quality of the left ventriculograms were distributed similarly between the groups. Because the catheter type and injection protocol did not affect the left ventriculogram quality in our study, variables determining opacification and overall quality rating are analyzed in the overall group of 190 patients. Left ventricular opacification was excellent in 72, acceptable in 108 and marginal in 10 patients. The patients with marginal opacification were significantly heavier (P = .004) with larger left ventricular enddiastolic volumes (P = .019), and smaller amount of contrast volume per enddiastolic volume (P = .005) and kilogram body weight (P = .003). The overall quality of left ventriculograms were excellent in 38, acceptable in 133, and marginal in 19 patients. The patients with excellent left ventriculograms were significantly younger (P = .019) and slightly less heavy (P = 0.09). Significantly more female patients were also in this group (P = .036). Ventricular tachycardia was the most common cause of unsatisfactory left ventriculograms. In the RAO view, deeper (more apical) placement of the catheter was associated with higher incidence of ventricular tachycardia (53%). The most "silent" area was the posterobasal area. In conclusion, the perfect left ventriculogram remains to be an elusive goal in routine clinical practice. When using 6F highflow pigtail catheters and nonionic contrast agents, more basal catheter position and higher contrast volume increase the quality of the left ventriculograms.

Hemodynamic changes pre- and post-pacing with complete heart block and aortic valve stenosis and regurgitation

Conduction disturbances in the setting of calcific aortic valve disease have been well documented in the literature. In this report we describe a case of a patient who presented in complete heart block and dyspnea on exertion. Subsequent non-invasive and invasive studies revealed moderate aortic stenosis and regurgitation with preserved left ventricular function. Hemodynamically important physiological pressure waveform changes occurred before and after pacing the ventricles and are highlighted here.

Maximal coronary flow reserve and metabolic coronary vasodilation in patients with diabetes mellitus

BACKGROUND

Structural and functional abnormalities of the coronary microcirculation have been reported in experimental diabetes mellitus. The purpose of this study was to evaluate coronary microvascular function in human diabetes.

METHODS AND RESULTS

Twenty-four diabetic and 31 nondiabetic patients were studied during cardiac catheterization. A Doppler catheter or guidewire was used to measure changes in coronary blood flow velocity in a nonstenotic artery. Maximal coronary blood flow reserve was determined by using intracoronary adenosine or papaverine. Coronary dilation in response to an increase in myocardial metabolic demand was assessed by using rapid atrial pacing. Maximal vasodilator responses to papaverine and adenosine were compared in 12 diabetic patients. Maximal pharmacologic coronary flow reserve was depressed in diabetic (2.8 +/- 0.2, n = 19) compared with nondiabetic (3.7 +/- 0.2, n = 21, P < .001) patients. During atrial pacing, the decrease in coronary vascular resistance was attenuated in the diabetic (-14 +/- 3%) compared with the nondiabetic (-24 +/- 2%, P < .05) patients. Differences in coronary microvascular function between diabetic and nondiabetic patients were not attributable to differences in drug therapy, resting hemodynamics, or incidence of hypertension. In 12 diabetic patients the maximal coronary vasodilator responses to papaverine and adenosine were similar.

CONCLUSIONS

This study demonstrates both reduced maximal coronary vasodilation and impairment in the regulation of coronary flow in response to submaximal increases in myocardial demand in patients with diabetes mellitus. These microvascular abnormalities may lead to myocardial ischemia in the absence of epicardial coronary atherosclerosis in some circumstances, and thus contribute to adverse cardiovascular events in diabetic patients.

Effect of adenosine antagonism on metabolically mediated coronary vasodilation in humans

OBJECTIVES

This study was performed to assess the importance of adenosine in mediating metabolic coronary vasodilation during atrial pacing stress in humans.

BACKGROUND

Numerous animal studies have examined the role of adenosine in the regulation of coronary blood flow, with inconsistent results.

METHODS

The effect of the adenosine antagonist aminophylline (6 mg/kg body weight intravenously) on coronary functional hyperemia during rapid atrial pacing was determined in 12 patients. The extent of inhibition of adenosine vasodilation was assessed using graded intracoronary adenosine infusions before and after aminophylline administration in seven patients. Coronary blood flow changes were measured with a 3F intracoronary Doppler catheter.

RESULTS

After aminophylline administration, the increase in coronary flow velocity during adenosine infusions was reduced from 84 +/- 48% (mean +/- SD) to 21 +/- 31% above control values (p < 0.001) at 10 micrograms/min and from 130 +/- 39% to 59 +/- 51% above control values (p < 0.001) at 40 micrograms/min. During rapid atrial pacing under control conditions, coronary blood flow velocity increased by 26 +/- 16%. The flow increment during paced tachycardia after aminophylline (23 +/- 10%) was unchanged from the control value, despite substantial antagonism of adenosine coronary dilation by aminophylline.

CONCLUSIONS

These data suggest that adenosine does not play an important role in the regulation of coronary blood flow in response to rapid atrial pacing in humans.

Simultaneous measurement of coronary flow reserve by left anterior descending coronary artery Doppler and great cardiac vein thermodilution methods

OBJECTIVES

The objective of this study was to compare left anterior descending coronary artery Doppler blood flow velocity and great cardiac vein thermodilution blood flow measurements of coronary flow reserve and submaximal coronary vasodilation in humans.

BACKGROUND

Reported maximal coronary flow reserve values obtained with the coronary venous thermodilution method are lower than those obtained with other measurement methods.

METHODS

Thermodilution measurements of great cardiac vein flow in 11 subjects were compared with simultaneous Doppler measurements of changes in left anterior descending coronary flow velocity after intracoronary administration of papaverine, nitroglycerin, iohexol and intravenous administration of dipyridamole.

RESULTS

Coronary flow reserve (papaverine peak/rest flow ratio) was 3.7 +/- 1.7 (mean +/- SD) by the Doppler method and 2.0 +/- 0.7 by the thermodilution technique (p less than 0.001). Thermodilution flow changes were also smaller than Doppler-measured changes during submaximal vasodilation and during prolonged coronary dilation after dipyridamole administration.

CONCLUSIONS

Coronary flow reserve and submaximal flow increases measured with the thermodilution method were consistently and substantially smaller than Doppler-derived measurements. This discrepancy has important implications for the comparison of coronary flow reserve measurements performed with the use of different techniques.

Formation of membrane-bounded secretory granules in the midgut epithelium of a termite, Cubitermes severus, and a possible intercellular route of discharge

Mature columnar cells of the midgut of Cubitermes contain a prominent secretion product observed at light- and electron-microscopic levels. At the ultrastructural level the product is resolved as an electron dense material contained in vesicles up to 1 micron diameter that accumulate in the apical cytoplasm. The vesicles are composite, apparently formed by coalescence of at least two types of precursor vesicle both of which originate from the Golgi apparatus. Discharge of the product takes place by exocytosis into intercellular space at or in the vicinity of the apical septate junction complex. Augmentation of apical surface area by microvilli is less prominent in Cubitermes than in other termites for which data are available. This and other evidence suggests that absorptive functions are reduced in the midgut of this insect.

Distribution and abundance of bacteria in the gut of a soil-feeding termite Procutiermes aburiensis (Termitidae, Termitinae)

The alimentary canal of a representative species of soil-feeding termite was examined for associations with bacteria. Enumerations made in the principal regions of the intestine by direct observation and expressed for comparative purposes as total microbial standing crop showed a net three- to fourfold increase between the foregut (crop) and rectum. Filamentous organisms, putatively actinomycetes, contributed significantly to the flora in most regions of the gut and were more abundant, relative to non-filamentous forms, than in freshly ingested soil. Transmission and scanning electron microscopy of the gut wall showed that the actinomycetes formed novel associations with the host in the mesenteron, mixed segment and colon. Non-filamentous organisms, chiefly rods, colonized the walls of the first proctodaeal segment and the colon, in addition to filaments, and were present in large numbers in the contents of the third proctodaeal segment.