Airway foreign body aspiration: common, yet easily overlooked! Two interesting cases

Two cases: A 66-year-old woman was referred to the hospital due to dyspnoea and cough. Seven months prior to referral, the patient had choked on a chunk of nut and grain-filled bread. She had daily cough and dyspnoea. The patient was convinced of an airway foreign body and she contacted her general practitioner and the emergency service several times; they all found this unlikely. Fibre optic bronchoscopy revealed two obstructing nut-like foreign bodies in the right upper and lower lobe, respectively. A 77-year-old man with sarcoidosis developed increased dyspnoea and sputum production. Three weeks earlier, the patient had choked on a magnesium tablet. Everyone was convinced that the tablet had dissolved. Infection was suspected. Chest CT scan was performed showing no obvious signs of infection or progression in sarcoidosis. After the CT scan, the patient coughed up the remains of the tablet and his symptoms resolved. Retrospective evaluation of the CT scan revealed the tablet.

Waste collection systems for recyclables: an environmental and economic assessment for the municipality of Aarhus (Denmark)

Recycling of paper and glass from household waste is an integrated part of waste management in Denmark, however, increased recycling is a legislative target. The questions are: how much more can the recycling rate be increased through improvements of collection schemes when organisational and technical limitations are respected, and what will the environmental and economic consequences be? This was investigated in a case study of a municipal waste management system. Five scenarios with alternative collection systems for recyclables (paper, glass, metal and plastic packaging) were assessed by means of a life cycle assessment and an assessment of the municipality's costs. Kerbside collection would provide the highest recycling rate, 31% compared to 25% in the baseline scenario, but bring schemes with drop-off containers would also be a reasonable solution. Collection of recyclables at recycling centres was not recommendable because the recycling rate would decrease to 20%. In general, the results showed that enhancing recycling and avoiding incineration was recommendable because the environmental performance was improved in several impact categories. The municipal costs for collection and treatment of waste were reduced with increasing recycling, mainly because the high cost for incineration was avoided. However, solutions for mitigation of air pollution caused by increased collection and transport should be sought.

The commutability of external quality assurance serum and reference serum materials between the VITROS® Albumin Slide and four other routine albumin methods

Background

Between-method differences in external quality assurance schemes (EQAS) are assumed to be indicative of between-method differences in results for fresh diagnostic serum samples. However, this assumption is only valid if the EQAS fluid is shown to be commutable between methods with the fresh human samples. Using fresh human serum samples, we studied the commutability of six UK National EQAS (UKNEQAS) samples and two reference serum preparations using five methods for the measurement of albumin.

Methods

The VITROS® Albumin Slide was compared with two liquid reagent bromocresol green-based methods and two immunoturbidimetric methods. Thirty fresh human serum samples, six UKNEQAS samples and two reference materials were analysed over a period of five days by all methods. The reference materials were: a certified protein reference material, CRM470 (protein reference preparation) and the Scandinavian NFKK Reference Serum X.

Results

A concentration-dependent tendency towards non-commutability was seen for the six UKNEQAS samples. Two of the methods recovered the CRM470 above the upper limit of the expected range and the remaining three were within the expected range.

Conclusions

Assessment of commutability is important in the investigation of between-method differences in EQAS. External quality assurance and reference materials should have been demonstrated to be commutable and be available at multiple concentrations, before they may be considered appropriate for the assessment of accuracy.

Microbiological assessments of compost toilets: in situ measurements and laboratory studies on the survival of fecal microbial indicators using sentinel chambers

Compost toilet systems were assessed for their ability to reduce microbial indicators and pathogens. Bacterial pathogens were not detected in any samples indicating a low survival rate in composting feces and/or an initial low occurrence. Indicator bacteria showed large variations with no clear trend of lower bacterial numbers after longer storage. In controlled composting experiments, thermophilic conditions were only reached when amendments were made (grass and a sugar solution). Even then it was impossible to ensure a homogenous temperature in the composting fecal material and therefore difficult to achieve a uniform reduction and killing of indicator organisms. Presumptive thermotolerant coliforms, Salmonella typhimurium Phage 28 B and eggs of Ascaridia galli, proved useful as indicators. However, regrowth was detected for enterococci and total numbers of bacteria grown at 36 degrees C. These indicator parameters may therefore overestimate the level of other (pathogenic) bacteria present in the material and can not be recommended for use as reliable indicator organisms in composting toilet systems. The addition of indicator bacteria to fecal material contained in semi-permeable capsules proved to be a useful technique to ensure that microorganisms were contained in a small test volume.

Detection of MTRR 66A-->G polymorphism using the real-time polymerase chain reaction machine LightCycler for determination of composition of allele after restriction cleavage

The MTRR gene codes for methionine synthase reductase, one of the enzymes involved in the conversion of homocysteine to methionine. This conversion influences the overall level of total plasma homocysteine (tHcy) and mutations, which reduces the enzyme activity and results in an increased concentration of tHcy. A high homocysteine level is a well-documented independent risk factor for cardiovascular disease. A polymorphism in the gene for methionine synthase reductase (MTRR 66 A>G) has been shown to be associated with the risk of giving birth to a child with Down's syndrome, and the risk of having a foetus with neural tube defects. We have established a method for analysing MTRR 66A>G on DNA from dried blood spots using melting temperature analysis. The DNA was extracted from dried blood spots using a fast procedure by boiling only.

A longitudinal study of serum cobalamins and its binding proteins in lactating women

OBJECTIVE

To examine longitudinal changes in serum cobalamins, transcobalamin (TC) and haptocorrin (HC) during lactation and to investigate the influence of vitamin B12 supplementation on these parameters.

DESIGN

A 9-month follow-up study.

SUBJECTS AND METHODS

Lactating mothers (N=89) including 23 supplemented with vitamin B12 (1-18 microg/daily), 41 partly supplemented and 25 not supplemented. Blood samples collected 3 weeks (baseline) and 4 and 9 months post-partum were analysed for cobalamins, TC and HC. Both the total concentration and the cobalamin-saturated form (holo) of TC and HC were analysed.

RESULTS

No significant differences were observed in serum cobalamins or its binding proteins related to supplementation with vitamin B12 or the duration of lactation. Serum cobalamins remained unchanged from 3 weeks to 9 months post-partum. Total TC (holoTC) (median+/-s.e. pmol/l) decreased between 3 weeks (710+/-23 (85+/-12)) and 9 months (602+/-21 (76+/-11)) (P<0.0001 (P=0.0002)), whereas total HC (holoHC) increased from (422+/-11 (300+/-9)) at 4 months to (455+/-13 (317+/-10)) to 9 months post-partum (P<0.0001 (P<0.0001)).

CONCLUSION

We report a decrease in TC and an increase in HC during a 9-month period post-partum. No differences were observed between the vitamin B12-supplemented and the unsupplemented groups. Thus, supplementation with vitamin B12 has no impact on the circulating level of serum cobalamins or its binding proteins in a Danish population of lactating mothers.

Folate and vitamin B12 in relation to lactation: a 9-month postpartum follow-up study

OBJECTIVE

To investigate the relation between lactation and markers of folate and vitamin B12 (B12) deficiency in women with and without vitamin supplementation.

DESIGN

A 9-month follow-up study.

SUBJECTS AND METHODS

Blood samples from 91 women, who gave birth to a single healthy child, were collected 3 weeks, 4 and 9 months postpartum and analysed for circulating level of homocysteine (tHcy), methylmalonic acid (MMA), folate and B12. The participants were categorized as exclusively, partly or not breast-feeding dependent on the degree of lactation 4 months postpartum. During follow-up, lifestyle factors were recorded by structured interviews.

RESULTS

Among 72 exclusively breast-feeding women, the median (10-90% percentile) tHcy was 5.8 (3.1-8.3) micromol/l 3 weeks postpartum, 6.1 (4.1-10.3) micromol/l 4 months postpartum and 5.3 (3.6-8.7) micromol/I 9 months postpartum. At 9 months postpartum, none of the women breast-fed exclusively. No significant change occurred in the concentration of B12 and folate. Exclusively breast-feeding women without vitamin supplementation had higher median tHcy than supplemented exclusively breast-feeding women 4 and 9 months postpartum (7.0 vs 5.4 micromol/l (P < 0.001) and 5.8 vs 4.5 micromol/l (P = 0.003), respectively). Six women had increased (>15 micromol/l) tHcy; four of these were unsupplemented and exclusively breast-feeding.

CONCLUSION

We found no overall indication of depletion of the folate and B12 stores during the lactation period in this population. However, folate-supplemented women had lower tHcy and higher folate levels, suggesting a beneficial effect of supplementation with folate throughout lactation.

Exercise, hormones, and body temperature. regulation and action of GH during exercise

That physical exercise stimulates pituitary GH secretion has been known for forty years, but the underlying mechanisms as well as the physiological significance remain elusive. We have previously shown that the concomitant increase in core temperature is essential for the exercise-induced GH release, inasmuch as exercise performed at 4 C results in a suppression of GH secretion, whereas passive heating constitutes a potent stimulus for GH release. Moreover, studies in normal subjects show that GH stimulates sweat production and evaporative heat loss during heat exposure with and without exercise, whereas GH-deficiency is associated with reduced sweat secretion and increased heat storage during similar conditions. The neurotransmitters involved in GH secretion during exercise remain uncertain; we therefore investigated the putative role of ghrelin, which is a gut-derived endogenous ligand for the GHS receptor. We measured circulating ghrelin levels before during and after submaximal aerobic exercise in healthy subjects and GH-deficient patients. The circulating ghrelin levels were unchanged during and after exercise in all subjects. Growth hormone stimulates lipolysis and lipid oxidation during basal and fasting conditions and we recently investigated whether GH also regulates substrate metabolism during exercise. The design involved GH-deficient patients studied during exercise with and without GH administration as compared to untreated healthy subjects. Growth hormone predominantly stimulated the turnover of free fatty acids in the recovery phase after exercise.

CONCLUSIONS

1) the increase in GH release during exercise is associated with the concomitant increase in body temperature, 2) GH stimulates sweat secretion and heat evaporation during exercise, which seems to be of distinct physiological significance, 3) ghrelin is not involved in exercise-induced GH release, 4) the impact of GH on substrate metabolism during exercise includes increased FFA turnover.

Evaluation of the DPC IMMULITE 2000 assay for total homocysteine in plasma

The present report describes an evaluation in three laboratories of the completely automated total homocysteine immunoassay adapted to the IMMULITE 2000 from DPC. The precision depended on the control materials used, but with quality control materials and patient samples imprecisions were found to be in the range of 5.3 to 6.1% and 5.4 to 6.0%, respectively. Dilution experiments proved the assay to be linear and correlations with HPLC and GC-MS methods were close (r=0.98 and 0.97, respectively). In addition, the samples from the Nordic program for external quality assessment of methylmalonic acid and homocysteine for 2000 were assayed in the three laboratories. Imprecision evaluated from these samples was 5.3% and the recovery of the added L-homocystine was equivalent to the mean recovery of the 58 participants in the program. The precision is close to the quality goals. In conclusion, the method is an attractive alternative when coping with an increasing number of requests for the analysis of total homocysteine.

Remifentanil vs. alfentanil for direct laryngoscopy: a randomized study comparing two total intravenous anaesthesia techniques. TIVA for direct laryngoscopy

The ideal anaesthesia for direct laryngoscopy is profound and yet brief. The present study sought to determine whether a new anaesthetic technique based on infusion of the ultra short-acting opioid remifentanil was superior to our routine alfentanil multiple-dose technique in terms of haemodynamic stability, stress responses and recovery. A total of 58 patients were randomized to receive propofol and either remifentanil or alfentanil as part of a total intravenous anaesthesia. In the remifentanil group, systolic blood pressure during anaesthesia remained significantly lower than baseline values, while it increased significantly in the alfentanil group. None of the patients receiving remifentanil showed stress responses (hypertension, tachycardia, somatic or autonomic responses), compared to 22 patients (79%) in the alfentanil group (P < 0.0001). In the remifentanil group, hypotension or bradycardia requiring intervention arose in 5 (18%) and 3 patients (11%); neither response was seen in the alfentanil group. The period from the end of propofol infusion until extubation was 5 min longer in the remifentanil group (P < 0.0001), whereas the time from extubation until discharge was similar in the two groups. Thus, neither technique showed sufficient haemodynamic stability, and further studies are needed to determine optimal dosages of propofol and opioid.

Platelet activity and in vivo arterial thrombus formation in rats with mild hyperhomocysteinaemia

Elevated plasma levels of total homocysteine (hcy) have been associated with an increased occurrence of arterial thrombosis. In the present study, we investigated the influence of hyperhomocysteinaemia on platelet aggregation and arterial thrombus formation in vivo. Fifty-one rats were included in the study, of which 29 received hcy in the drinking water for 4 weeks. Blood samples were withdrawn for measurement of platelet count and mean platelet volume. Platelet aggregation response in platelet-rich plasma following adenosine diphosphate or collagen stimulation were examined. In vivo thrombus formation was investigated by transillumination and videotape recording of the rat femoral artery after a thrombogenic injury was established. Off-line videotape analysis using computer-assisted planimetry permitted quantification of the thrombus area, and area versus time curves were obtained. In the intervention group receiving hcy, total hcy in plasma increased two-fold to 14.3 micromol/l, as compared with 7.3 micromol/l in the control group (P < 0.001). The platelet count and mean platelet volume did not differ between the two groups. In vivo thrombus formation expressed as the area under the curve or maximum thrombus area was not found to be altered in the presence of an increased homocysteine level, neither was adenosine diphosphate-induced platelet aggregation. However, collagen-induced platelet aggregation significantly decreased in the hcy group (P = 0.02). Pro-thrombotic effects of isolated mild hyperhomocysteinaemia are not supported by the present study in rats.

Homocysteine and atherothrombosis

Atherosclerosis with or without thrombosis superimposed is the most frequent cause of ischemic heart disease (IHD), peripheral arterial disease, and a main cause of stroke. Conflicting results have been reported in genetic, observational, and experimental studies on the relationship between homocysteine and these atherothrombotic diseases. Although cardiovascular complications are common in homocystinuric patients (severe hyperhomocysteinemia), IHD, the most frequent manifestation of atherothrombosis in the general population, appears to be rare. On the basis of findings in individuals with hyperhomocysteinemia of genetic origin, there is in fact no clear evidence for a causal role of homocysteine in the pathogenesis of atherothrombotic disease, and the positive association between plasma homocysteine and IHD observed in many, but not all epidemiologic studies does not prove causality. To infer causality from observational studies, there should be a temporal, consistent, strong, independent, graded (dose-response effect), and duration-dependent relationship between exposure and outcomes, and a biologically plausible mechanism should exist. The relationship between plasma homocysteine levels and IHD does not fulfill these criteria beyond reasonable doubt. In the general population, plasma homocysteine levels are to a great extent determined by dietary habits, and plasma homocysteine could be a marker, or a consequence, of atherothrombosis and/or risk-associated behavior (e.g., a diet low in fruits and vegetables) rather than a cause of atherothrombosis. Experimentally, hyperhomocysteinemia is not in itself atherogenic in normal animals with relatively low plasma cholesterol levels. The homocysteine theory of atherosclerosis should be tested more thoroughly in hypercholesterolemic animals that develop atherosclerosis spontaneously to determine whether elevated plasma homocysteine levels are harmful under atherogenic conditions. A causal role of homocysteine in atherothrombotic disease remains to be established.