[Effect on the microbicidal efficacy of formaldehyde, glutardialdehyde, peracetic acid, chloramine T (N-chloro-4-toluenesulfonamide), m-cresol, ethanol and benzyldimethyldodecacylammonium bromide by blood (model experiments for chemical disinfection of instruments)]

In a preceding paper (Zbl. Hyg. 191 [1991] 457-477) we reported on the dependence of the microbicidal efficacy of active agents of the disinfection of instruments on the amount of coagulated blood adhering to the instruments. In the present investigation, we were interested in the dependence of the microbicidal effects on the amount of blood in the solutions of the active agents. Test areas of 2 cm2 were contaminated with 50 and 100 microliters coagulating blood, respectively, containing cells of Staphylococcus aureus as test germ. The solutions of the microbicidal agents were contaminated with heparinized blood up to a concentration of 4% immediately before starting the disinfection and 24 hours before, respectively. After a period of action lasting 1 hour at 20 degrees C, the relative number of test germs capable of multiplying (N/N0) was determined. The concentration of the microbicidal substances reducing the relative number of test germs capable to multiply to 10(-4) served for estimating the dependence of the microbicidal efficacy of the agents on the blood content of the solutions. The experimental results depended on the thickness of the layer of coagulated blood. The dependence of the efficacy of the microbicidal substances on the blood content of the solutions was the higher the thinner the blood layer was. At a thickness of the layer of the coagulated blood of 0.25 mm, a blood content of the solution of 4%, and applying it immediately after adding the blood, the concentration of glutardialdehyde had to be 1.6 times that without blood to reach the same microbicidal efficacy. When applying the solution 24 hours after adding the blood, the concentration of glutardialdehyde had to be 4.2 times that without blood. The quaternary ammonium compound reacted faster with the blood than did glutardialdehyde; the respective factors were 2.6 and 4.5. The concentration factors of chloramine T were 3.3 and 3.8. Under the conditions of the test, peracetic acid exhibited small concentration factors: 1.3 and 1.6. The microbicidal efficacy of ethanol, formaldehyde and m-cresol soap solution was not or only slightly altered by the amount of blood in the solution of the microbicidal agent.

[Effect of protamine on the microbicidal efficacy of formaldehyde]

Testing the ability of commercial compounds to provide an effective disinfection of instruments requires test conditions that are close to reality which includes the proper selection of the material used to contaminate the test objects. The adhesion of the material must be strong enough to keep it attached to the test object during and after insertion into the disinfectant solution. Its characteristics should come as close as possible to those of the contaminations encountered in practice. The guideline for instrument disinfectants published by the Robert Koch-Institute recommends the use of coagulated blood. Accordingly, heparinized sheep blood is mixed with the test germs, and protamin is added to initiate coagulation. In the present investigation we compared this contamination procedure with a second one, in which coagulation was achieved by adding a CaCl2 solution to citrate blood. We also included agarose as an almost inert contaminant in our experiments. The results showed that protamine is able to increase the microbicidal efficacy of formaldehyde on staphylococci significantly. When these test germs were embedded either in citrat blood or in agarose, it took about twice the disinfectant concentrations to achieve the same microbicidal effects as with protamine blood (Fig. 1). Remarkably, the results obtained with citrate blood were the same as those with agarose, regardless of the differences in material between the two contaminants. It should also be noted that the microbicidal effect of the formaldehyde proved to be almost independent from the amount of contaminant per test area, hence, from the thickness of the layer. When M. terrae was employed as test germ, the results obtained with protamine blood and citrate blood, respectively, as contaminants were identical (Fig. 2). The same was true for the other test germs investigated, except for E. faecium (Fig. 3). The addition of even very small amounts of protamine to the embedding compound, agarose led to a substantially increased efficacy of the formaldehyde against staphylococci (Fig. 4). This effect was especially distinct in suspension (Fig. 5). Whenever the efficacy of formaldehyde-containing disinfectants is to be tested and evaluated, one should be aware of this synergism between protamine and formaldehyde. In these cases, it is advised to employ other contaminating agents, such as coagulated blood prepared by addition of CaCl2 to citrate blood.

Role of calcium ions in acidosis-induced glial swelling

Tissue acidosis occurring in cerebral ischemia and traumatic brain injury is a mediator of cytotoxic brain edema. In vitro, extracellular lactacidosis induces swelling of glial cells in a dose dependent manner. pH-regulatory membrane transporters and channels have been identified which are involved in the increase of the glial cell volume. Underlying mechanisms of their activation are poorly understood, however. We have, therefore, addressed the question, whether and how Ca(2+)-ions play a role in acidosis-induced glial swelling and intracellular acidification. For that purpose C6 glioma cells were suspended and the pH in the medium was lowered from 7.4 (baseline) to 6.2 by isotonic lactic acid. Cell volume and intracellular pH (pHi) were assessed by flow cytometry. In the presence of Ca(2+)-ions the cell volume reached a maximum of 125.1% from acidosis. In experiments using a calcium-free suspension medium, cell swelling from acidosis was inhibited by 74%. Additional buffering of intracellular calcium (Ca2+i) had no further inhibitory effect on acidosis-induced cell swelling, while buffering of Ca2+i by BAPTA-AM alone did not affect the glial volume increase secondary to administration of lactic acid. pHi which was decreasing from acidosis was not affected by the experimental modifications of the Ca(2+)-concentration in the medium or cytosol. The present data indicate that lactacidosis-induced glial swelling depends on the presence of extracellular Ca(2+)-ions, while release of Ca(2+)-ions from intracellular stores does not seem to be involved.

Effect of alpha-trinositol on swelling and damage of glial cells by lactacidosis and glutamate

The therapeutic efficacy of alpha-trinositol (D-myo-inositol-1,2,6-trisphosphate), an isomer of the intracellular messenger IP3, was analyzed for cytotoxic swelling and damage of glial cells in vitro from lactacidosis or glutamate. Lactacidosis and the interstitial accumulation of glutamate are prominent sequelae in ischemic or traumatic brain tissue. C6 glioma cells harvested from culture and suspended in a physiological medium were either exposed to pH 5.0 by administration of lactic acid, or to 1 mM glutamate at normal pH. Cell swelling and viability were quantified by blood flow cytometry. Addition of alpha-trinositol (3 mM) under control conditions at pH 7.4 resulted in transient cell shrinking to 96.5 +/- 1.3% of control within 3 min (p < 0.05). Lactacidosis of pH 5.0 led to an increase in cell volume to 139.7 +/- 1.3% within 20 min, whereas alpha-trinositol reduced the swelling response by approximately 25% (p < 0.01). In addition, cell viability was severely affected at pH 5.0 amounting to only 53.8 +/- 3.1% after 60 min. alpha-Trinositol was found to markedly improve cell viability; at 60 min 70.2 +/- 1.6% of the cells were still viable (p < 0.01). Addition of glutamate (1 mM) led to a steady increase in cell size, reaching 110% of control after 120 min, irrespective of wether alpha-trinositol was present or not. The attenuation of cell swelling may be attributed to an interference with pH-regulatory mechanisms, such as the Na+/H(+)-antiporter, while protection of cell viability might be caused be effects of alpha-trinositol on Ca(2+)-overload. On the other hand, the increase in cell volume by glutamate associated with its intracellular uptake was not influenced by alpha-trinositol.

Effect of mild and moderate hypothermia on the acidosis-induced swelling of glial cells

The effect of mild (32 degrees C) and moderate (27 degrees C) hypothermia was analyzed on the cell volume and intracellular pH (pHi) of C6 glioma cells at normal pH and during lactacidosis at pH 6.2 in vitro. The cells were suspended in an incubation chamber under continuous control of pH, PO2 and temperature. Cell swelling was quantified by an advanced Coulter-system. pHi was measured by flow cytometry using the fluorescent dye bis-carboxyethyl carboxyfluorescein (BCECF). Following a control period at 37 degrees C, the ambient temperature was decreased to 32 degrees C for 30 min, and subsequently to 27 degrees C for another 30 min. Hypothermia alone led to an immediate and significant cell volume increase of 107.3 +/- 0.4% (mean +/- SEM) of control after 30 min at 32 degrees C, and further swelling to 110.5 +/- 0.9% after 30 min at 27 degrees C. Yet, hypothermia (27 degrees C) afforded partial protection against the acidosis-induced cell swelling at pH 6.2, which was reaching to 120.4 +/- 0.9% in the normothermic control group after 60 min, while only to 111.3 +/- 0.9% at 27 degrees C. Hypothermia, however, was associated with a more pronounced decrease of the pHi during acidosis (6.3 +/- 0.04) as compared to that of the normothermic control falling then to 6.5 +/- 0.03. The results demonstrate that mild and moderate hypothermia induce glial cell swelling, but simultaneously inhibit cell swelling from acidosis. The protection against cell swelling, however, has its price as indicated by the enhancement of the intracellular acidification.

[Bronchial carcinoma developing in a tuberculous scar: computer tomographic follow up]

The development of scar is a rare complication of lung tuberculosis which was yet not often demonstrated in the radiologic literature. We report on a 71 year old male suffering by lung tuberculosis in an active stage which developed lung cancer in the region of tuberculotic scar clearly depicted on computed tomography. To the best of our knowledge this is the first reported computed computed tomography control series dealing with this problem. Additionally we report on histopathologic findings showing an early cancer in the surrounding of a tuberculotic scar.

A review of the factors influencing nonrecurrence of venous leg ulcers

The literature on external prevention strategies for recurrence of venous leg ulcers is reviewed to assess the extent of existing knowledge and the effectiveness of preventive practices currently employed. Although there is some evidence that the use of compression hosiery is effective in reducing the incidence of recurrence, other strategies cited for ulcer prevention are not supported by documented research. It is also evident that patient compliance with wearing compression hosiery could be improved and that an evaluation of the effectiveness of hosiery currently available is overdue. With district nurses spending up to 50% of their time treating venous leg ulcers, not only are they in a key position to disseminate information on effective prevention to patients, but in so doing they should contribute to a reduction in their leg ulcer treatment caseload. To do this, nurses need to be more informed on aspects of venous leg ulceration and prevention strategies.

Effect of positive end-expiratory pressure on the incidence of venous air embolism and on the cardiovascular response to the sitting position during neurosurgery

We have studied prospectively the effect of 10 cm H2O of PEEP on the incidence of venous air embolism and on the cardiovascular response to change from the supine to the seated position in a large neurosurgical population. Patients were allocated randomly to receive either PEEP (10 cm H2O, n = 45) or conventional (control, n = 44) ventilation. Cardiovascular and respiratory variables were measured in the supine and sitting positions, and monitoring included precordial Doppler probe, pulmonary artery pressure and expiratory carbon dioxide concentration. Venous air embolism was assumed if changes in precordial Doppler sounds occurred, end-tidal carbon dioxide concentration decreased or air could be retrieved from a central venous multi-orifice catheter. The incidence of venous air embolism (26%) did not differ between patients undergoing conventional ventilation and those undergoing ventilation with 10 cm H2O of PEEP. Venous air embolism was always detected first by alterations in Doppler sounds. Cardiac output was significantly higher in patients undergoing conventional ventilation than in those undergoing ventilation with PEEP in the supine but not in the sitting position. Furthermore, pulmonary vascular resistance increased significantly only in the upright position in those undergoing ventilation with PEEP. The pulmonary artery wedge pressure to central venous pressure gradient did not attain negative values with PEEP or with upright positioning. We conclude that the use of PEEP during neurosurgical procedures performed in the sitting position should be abandoned as it does not decrease the incidence of venous air embolism but is associated with significant adverse cardiovascular effects.

Economic burden of environmental tobacco smoke on Hong Kong families: scale and impact

STUDY OBJECTIVE

To examine the financial cost of doctor consultations for cough, phlegm, and wheeze in children living in a home where family members smoke compared with those not exposed to environmental tobacco smoke. To model these costs to provide the Territory of Hong Kong with estimates of potentially avoidable health care resource use.

DESIGN

Cross sectional questionnaire survey.

SUBJECTS AND SETTING

All children (10,615) in classes primary 3 to 6 (aged 8-13 years) attending 27 schools in two districts of Hong Kong in 1992 and their parents.

MEASUREMENTS AND MAIN RESULTS

Doctor consultations during the previous three months for symptoms of either cough, phlegm or wheeze were higher in younger children, ranging from 22.9% in 8 year olds to 8.4% in those aged 12 or over. For those children living in homes with one, or more than one, smoker category (there were four categories of smokers: father, mother, siblings, others), the adjusted odds ratios (95% confidence intervals) for a doctor consultation for any of these symptoms were 1.15 (1.01, 1.31) and 1.38 (1.14, 1.67) respectively. Using US$15 as the minimum cost incurred per consultation, the expected direct cost per annum per child of doctor consultations was 14% higher for children living in a one smoker category home and 25% for two or more compared with exposure to no smokers in the home. Using these values on a territory wide basis, the annual avoidable direct cost associated with exposure to tobacco smoke in children from birth to 12 years of age ranged from US$338,042 to US$991,591.

CONCLUSIONS

Exposure to environmental tobacco smoke not only provides a respiratory health risk for children but also an avoidable excess cost to the family's financial resources and health service providers.

From laboratory to clinic: a large scale study of distortion product otoacoustic emissions in ears with normal hearing and ears with hearing loss

OBJECTIVES

1) To describe distortion product otoacoustic emission (DPOAE) measurements in large groups of subjects with normal hearing and with hearing loss, and to use these data to provide comprehensive descriptions of DPOAE test performance. 2) To describe the effects of primary frequency and audiometric threshold on the extent to which DPOAE measurements accurately identify auditory status. 3) To develop an approach that describes the probability that any measured response is coming from either a normal or an impaired ear. 4) To develop an approach for representing DPOAE data clinically. 5) To explore the relation between magnitude of hearing loss and DPOAE measurements.

DESIGN

DPOAE measurements were made in 1267 ears of 806 subjects, using stimulus conditions that previously had been demonstrated to result in the greatest separation between normal and impaired ears (i.e., primary levels of 65/55 dB SPL for f1/f2; Stover et al., 1996). Subjects were recruited from local clinical populations and through local advertisements. All data were analyzed using clinical decision theory, including relative operating characteristic (ROC) curves and estimates of areas under these curves (Az). In addition, cumulative distributions were constructed of response properties from both normal and hearing-impaired ears. These cumulative distributions were used to select specific probabilities that measured responses were coming from either the normal or impaired distributions, and to develop an approach for describing clinical DPOAE data.

RESULTS

For no conditions were the distributions of DPOAE responses from normal and impaired ears completely separated, meaning that optimal criterion values would still result in errors in identification of auditory status. Test performance, defined by Az, was best for mid and high frequencies and poorest for lower frequencies and for the highest frequency tested (8000 Hz). Performance was best when normal hearing was defined as audiometric thresholds between 20 and 30 dB HL, with poorer performance for more stringent or lax audiometric criteria.

CONCLUSIONS

Within the limits related to the effects of primary frequency and audiometric criterion, it appears that DPOAE measurements can be used to accurately identify auditory status. An approach is described, using the present data set, that allows one to assign to any measured DPOAE value (DPOAE amplitudes, DPOAE/noise) the probability that the response is coming either from the distribution of normal or impaired responses. In addition, DPOAE/noise systematically decreases as hearing loss increases over the range of hearing losses from 0 to about 40 to 60 dB HL (depending on frequency), thus potentially enabling one to differentiate hearing losses over this range. For hearing losses greater than 50 to 60 dB HL, ears do not produce measurable DPOAEs and thus, no predictive relationship exists.

The influence of antithrombin III (AT III) substitution to supranormal activities on systemic procoagulant turnover in patients with end-stage chronic liver disease

OBJECTIVE

Since antithrombin III (AT III) substitution to normal activities could not be shown to have major beneficial effects in patients with end-stage chronic liver disease in a variety of clinical settings, we tested the hypothesis that substitution to supranormal activities decreases systemic procoagulant turnover better in this patient group.

DESIGN

Controlled prospective clinical study.

SETTING

Operating rooms at a University Hospital.

PATIENTS

Twenty-four patients with histologically verified liver cirrhosis consecutively scheduled for liver transplantation.

INTERVENTIONS

Nineteen patients were given an antithrombin III concentrate to achieve either 100% (n = 10) or 175% (n = 9) AT III activity. Control patients (n = 5) received saline 0.9% instead.

MEASUREMENTS AND RESULTS

Molecular markers of coagulation activation, platelet count and aggregability, and global coagulation variables were measured prior to AT III infusion and 60 min thereafter. In both AT III-treated groups thrombin-antithrombin III-complex increased significantly (p < 0.005), whereas prothrombin fragment F1 + 2, soluble fibrin and D-dimer concentrations, as well as other variables, did not show major changes.

CONCLUSIONS

Despite thrombin inhibition by AT III in patients with end-stage chronic liver disease, systemic procoagulant turnover was not significantly decreased 60 min after AT III application even to supranormal activities. Replenishment of the inhibitory antithrombin III pool, decreased in chronic liver disease, should not be expected to slow down the baseline consumptive component of the haemostatic disorder in this patient group.

[The dromedary: ancestry, history of domestication and medical treatment in early historic times]

Research on camel bones from archaeological excavations in North Africa and the Near East contradict the current opinion in textbooks that the dromedary and the Bactrian camel are domesticated forms derived from a single species, the two-humped wild camel (C. ferus). The probable ancestor of the domestic one-humped camel is Thomas' camel (C. thomasi). The wild dromedary was probably domesticated on the Arabian peninsula, perhaps as early as the 4th millennium BC. From the 2nd millennium BC onward there is evidence for the use of the one-humped camel for riding and transport purposes. Camel-keeping also implied the therapy of diseased animals, the main source of information about their treatment being medieval arabic texts dealing with veterinary medicine. An expert of such an early 13th century text is presented and discussed. From this it can be seen that the medieval camel treatment fits the principles of the so-called humoral theory, a medical concept which at that time already existed for more than 1500 years.

Genetic and functional analysis of neuronatin in mice with maternal or paternal duplication of distal Chr 2

Functional differences between parental genomes are due to differential expression of parental alleles of imprinted genes. Neuronatin (Nnat) is a recently identified paternally expressed imprinted gene that is initially expressed in the rhombomeres and pituitary gland and later more widely in the central and peripheral nervous system mainly in postmitotic and differentiating neuroepithelial cells. Nnat maps to distal chromosome (Chr) 2, which contains an imprinting region that causes morphological abnormalities and early neonatal lethality. More detailed mapping analysis of Nnat showed that it is located between the T26H and T2Wa translocation breakpoints which is, surprisingly, proximal to the reported imprinting region between the T2Wa and T28H translocation breakpoints, suggesting that there may be two distinct imprinting regions on distal chromosome 2. To investigate the potential role of Nnat, we compared normal embryos with those which were PatDp.dist2.T26H (paternal duplication/maternal deficiency of chromosome 2 distal to the translocation breakpoint T26H) and MatDp.dist2.T26H. Expression of Nnat was detected in the PatDp.dist2.T26H embryos, where both copies of Nnat are paternally inherited, and normal embryos but no expression was detected in the MatDp.dist2.T26H embryos with the two maternally inherited copies. The differential expression of Nnat was supported by DNA methylation analysis with the paternally inherited alleles being unmethylated and the maternal alleles fully methylated. Although experimental embryos appeared grossly similar phenotypically in the structures where expression of Nnat was detected, differences in folding of the cerebellum were observed in neonates, and other more subtle developmental or behavioral effects due to gain or loss of Nnat cannot be ruled out.

Behavioral and functional analysis of mouse phenotype: SHIRPA, a proposed protocol for comprehensive phenotype assessment

For an understanding of the aberrant biology seen in mouse mutations and identification of more subtle phenotype variation, there is a need for a full clinical and pathological characterization of the animals. Although there has been some use of sophisticated techniques, the majority of behavioral and functional analyses in mice have been qualitative rather than quantitative in nature. There is, however, no comprehensive routine screening and testing protocol designed to identify and characterize phenotype variation or disorders associated with the mouse genome. We have developed the SHIRPA procedure to characterize the phenotype of mice in three stages. The primary screen utilizes standard methods to provide a behavioral and functional profile by observational assessment. The secondary screen involves a comprehensive behavioral assessment battery and pathological analysis. These protocols provide the framework for a general phenotype assessment that is suitable for a wide range of applications, including the characterization of spontaneous and induced mutants, the analysis of transgenic and gene-targeted phenotypes, and the definition of variation between strains. The tertiary screening stage described is tailored to the assessment of existing or potential models of neurological disease, as well as the assessment of phenotypic variability that may be the result of unknown genetic influences. SHIRPA utilizes standardized protocols for behavioral and functional assessment that provide a sensitive measure for quantifying phenotype expression in the mouse. These paradigms can be refined to test the function of specific neural pathways, which will, in turn, contribute to a greater understanding of neurological disorders.

Interaction between haematocrit and pulmonary blood volume on pulmonary vascular flow resistance and pressure flow relationships

OBJECTIVE

Pulmonary vascular flow resistance depends on blood viscosity, mainly due to haematocrit, and on vessel dimensions determining blood volume in this highly compliant vascular bed. We, therefore, evaluated the interaction between haematocrit, blood flow, and transpulmonary vascular pressure gradient under conditions of controlled pulmonary blood volume.

DESIGN

Experimental study in isolated zone-III rabbit lungs perfused with autologous blood.

SETTING

Laboratory for experimental studies.

INTERVENTIONS

Stepwise and independent variation of flow (50, 100, and 200 ml/min), pulmonary blood volume (increments of 2.5 ml and 5 ml imposed by changes of left atrial pressure), and haematocrit (0-50%) varied by haemodilution (Krebs-Henseleit/albumin) or haemoconcentration (centrifugation).

MEASUREMENTS

Pulmonary arterial, left atrial, and airway pressures as well as reservoir volume (reflecting reciprocal changes of lung blood volume) and lung weight.

RESULTS

Haemodilution from the normal haematocrit (32%) to 10% at constant pulmonary blood volume and flow decreased flow resistance only slightly, whereas haemoconcentration (50%) increased flow resistance up to 130%. At the same time increments of in pulmonary blood volume of 2.5 and 5 ml (approx. 15 and 30% of normal pulmonary blood volume) at constant haematocrit significantly shifted downwards pressure-flow relationships for all investigated haematocrits (0-50%).

CONCLUSIONS

Because of the multiple interrelationships between haematocrit, blood flow and pulmonary blood volume, haematocrit effects on pulmonary flow resistance and pressure-flow relationships in the pulmonary vasculature should be studied at controlled blood volume. While haemodilution only has minor effects, haemoconcentration changes pressure-flow relationships markedly. Pulmonary blood volume has a major impact on slope and position of pressure-flow relationships for all haematocrits investigated.

The effect of delayed analysis or freeze-thawing on the measurement of natural anticoagulants, resistance to activated protein C and markers of activation of the haemostatic system

We provide a centralised thrombophilia screening service with sample transfer by courier or first class mail, a practice common to many centres. Sample quality is of prime importance, thus we have assessed the effect of delayed sample handling upon the haemostatic variables within our thrombophilia profile. This comprises screening for familial natural anticoagulant deficiency and APC resistance (1-4), and acquired lupus anticoagulant (5,6). The effect upon hypercoagulable markers were also assessed to facilitate evaluation of these in prospective clinical studies (7).

Vaginal Ureaplasma urealyticum colonization: influence on pregnancy outcome and neonatal morbidity

The effects of Ureaplasma urealyticum colonization on pregnancy and neonatal outcome was prospectively studied in women with impending term or preterm delivery. One hundred and seventy women colonized with U. urealyticum as the only pathogenic microorganism and 83 women with negative cultures were enrolled for study. Compared to the controls, U. urealyticum colonization was associated with a significantly increased rate of amnionitis (2% vs 35%; p < 0.001), chorioamnionitis (0% vs 10%; p < 0.05), premature rupture of membranes (12% vs 35%; p < 0.001) and preterm delivery (10% vs 41%; p < 0.001). The rate of vertical transmission ranged from 38% in term infants to 95% in very low birth weight infants. U. urealyticum colonization at birth was associated with an increased risk for the development of respiratory distress syndrome (9% vs 51%), intraventricular hemorrhage (1% vs 7%) and bronchopulmonary dysplasia (4% vs 17%) in very low birth weight infants (< 1500 g). It is concluded that maternal U. urealyticum colonization is associated with amnionitis, chorioamnionitis and preterm delivery, and that tracheal colonization with U. urealyticum increases the risk for respiratory and neurological complications in very low birth weight infants.