Effect of media composition on long-term in vitro stability of barium alginate and polyacrylic acid multilayer microcapsules

For a number of applications stability of microcapsules is a critical factor. Since the maintenance of polyelectrolyte complexes depends considerably on the ion composition we tested the physical properties of barium alginate capsules and searched for conditions to improve stability by a multilayer coating with polyethylenimine (PEI) and polyacrylic acid (PAA). Mechanical stability and diameters were determined in barium alginate capsules and compared with multilayer capsules. Multilayer coating resulted in smaller capsules than barium complexing alone. The difference was more pronounced when CaCl2 was used instead of NaCl during coating. Barium alginate capsules and application of CaCl2 during coating led to continuous pressure profiles, whereas NaCl resulted in bursting at a defined pressure, indicating the additional contribution to mechanical stability by the outer layers. After 7 d culture, mechanical stability of coated capsules decreased in RPMI and NaCl but was most pronounced in sodium citrate. The capsule diameter increased in sodium citrate, less pronounced in NaCl and was significantly different to RPMI and double distilled water. During long-term culture in RPMI, the diameter increased and mechanical stability decreased significantly. Multilayer coating improved mechanical stability which was impeded most in sodium citrate, to a lesser extent by NaCl and RPMI even after long-term exposure.

Gas cooking, respiratory health and white blood cell counts in children

The use of gas stoves has been associated with respiratory symptoms of chronic airway inflammation and higher rates of respiratory infections. We used data from a 1992/93 survey of 2,198 East German school children (aged 5 to 14) to assess whether gas cooking increases respiratory symptoms and is associated with a chronic inflammatory process reflected by an increase in white blood cell (WBC) count in children who do not exhibit signs of an acute respiratory infection. We found increases for the respiratory symptoms 'cough without cold' [odds ratio (OR) = 1.68; 95% confidence interval (CI), 1.18-2.39], 'cough in the morning' (OR = 1.58; CI, 1.23-2.04) and 'cough during the day or at night' (OR = 1.42; CI, 1.13-1.78) in children living in homes with gas ranges, but lifetime prevalence of asthma, bronchitis, wheeze, and the prevalence of acute infections were not affected. Furthermore, we examined WBC levels in a subgroup of 1,134 children for whom blood samples were available and who did not suffer from an acute infection. We observed small increases in the risk of having WBC counts above the 75th or 90th percentile (8300 or 9800 cell counts per microliter) when children were exposed to gas cooking after adjustment for age, gender, and passive smoking (OR = 1.30; CI, 0.98-1.73, and OR = 1.38; CI, 0.91-2.10). The strongest effect estimates for chronic inflammation were found for those children likely to have been exposed at higher levels, that is when stoves had no fans, in smaller homes, and for children spending more time indoors.

The effect of low-level blood lead on hematologic parameters in children

A health survey of school children living in polluted regions of eastern Germany provided us with data necessary to examine the effects of lead on the blood system at levels below current standards for blood lead content. Data collected for 797 children, aged 5-14 years, with low blood lead levels (GM, 33.3 microg Pb/L; range, 7.5-239 microg Pb/L) allowed us to examine the relationship between blood lead content and hematological parameters. Using linear regression analyses and controlling for a number of potential confounding factors, we found that increasing blood lead levels by 10 microg/L were associated with a small increase in the number of red blood cells and in girls with reduced MCV and MCH. The reasons for our observation, especially the gender difference, are still uncertain. In conclusion the morphology and function of erythrocytes might be sensitive parameters of low dose lead toxicity.

Myocardial ischemia and weaning failure in patients with coronary artery disease: an update

OBJECTIVE

To determine the frequency and effects of weaning-related myocardial ischemia on weaning outcomes in patients with coronary artery disease.

DESIGN

Prospective cohort study.

SETTING

Medical and cardiac intensive care units of a 300-bed teaching community hospital.

MEASUREMENTS AND MAIN RESULTS

Three-lead ST segments, heart rate-systolic blood pressure products, and respiratory rate/tidal volume ratios were obtained for patients with coronary artery disease just before and during their initial trials of weaning from mechanical ventilation. ST segments were interpreted by a blinded cardiologist. Eighty-three patients with a mean age of 72.4 +/- 1.1 years (mean +/- SEM), a mean Acute Physiology and Chronic Health Evaluation II score of 16.4 +/- 0.8, and a mean duration of mechanical ventilation of 4.6 +/- 0.9 days were studied. Eight patients showed electrocardiographic evidence of ischemia during weaning, and seven of these patients failed to be liberated on their first day of weaning. The presence of ischemia significantly increased the risk of weaning failure (risk ratio, 2.1; 95% confidence interval, 1.4-3.1). The rate-pressure product for the group as a whole increased significantly during weaning, from 11.9 +/- 0.4 to 13.5 +/- 0.5 mm Hg x beats/min x 10(3) (p < .01). The increase in rate-pressure product tended to be greater in patients who became ischemic (12.8 +/- 0.9 to 17.3 +/- 2.0 mm Hg x beats/min x 10(3)) than in patients who were not ischemic during weaning (11.8 +/- 0.4 to 13.0 +/- 0.5 mm Hg x beats/min x 10(3); p = .05). The rate/volume ratio did not change significantly during weaning, but the rate/volume ratios after both 1 min (65.6 +/- 4.6 vs. 98.0 +/- 9.4 breaths/min/L; p < .05) and 30 mins (68.6 +/- 4.3 vs. 91.1 +/- 8.9 breaths/min/L; p < .05) of unassisted breathing were lower in successful than in unsuccessful patients.

CONCLUSION

Electrocardiographic evidence of myocardial ischemia occurs frequently and is associated with significantly increased risk of first-day weaning failure in patients with coronary artery disease.

Trends in allergies among children in a region of former East Germany between 1992-1993 and 1995-1996

A lower prevalence of asthma and allergies has been reported among children and adults living in the area of former East Germany compared with those living in West Germany. After German reunification in 1990, the East German population rapidly adopted a western lifestyle. Therefore, this study examined if the prevalence rates of allergic diseases, symptoms, and sensitisation and asthma have increased among East German children since German reunification. - Children aged 5 to 7 years living in the region of Sachsen-Anhalt, East Germany were examined in two cross-sectional studies during 1992-93 (n = 769, response rate 84.0%) and 1995-96 (n = 725, response rate 74.6%). Sensitisation was assessed by specific immunoglobulin E measurements against five common aeroallergens using the CAP-FEIA technique. After adjustment for sex, parental education, season of examination, day care attendance, breast feeding, environmental tobacco smoke exposure, cat dander exposure, and several indoor factors, an increase in the prevalence of self-reported, physician-diagnosed allergies (OR 1.44, 95% CI 1.01-2. 06), but not in allergic sensitisation (OR 0.85, 95% CI 0.62-1.16) was found. The only evidence of an increase in allergies of the self-reported increase in the prevalence of physician-diagnosed allergies is likely due to changes in physician diagnostic patterns and the heightened public awareness of allergic diseases. - In conclusion, there were no significant changes in the prevalence of asthma, allergic rhinitis, or self-reported symptoms of allergic diseases.

[Memory complaints: what should be done? From consultation to the memory center]

Memory complaints are frequent and not always the result of a memory impairment. Such complaints must be taken into account since they always reflect some disorder, at least of attentional processes. Excepting primary psychiatric disorders, biological and imaging exams are required in addition to a neuropsychological and behavioral assessment. Finding the cause of the memory complaints is not an end in itself. The purpose is to cure or at least to relieve the consequences of this and related symptoms with pharmacological, neuropsychological and psychological therapies, social help, information and support. Patients (especially in case of dementia) and families need follow-up care by a multidisciplinary staff (neurologists, psychiatrists, psychologists, speech therapists, nurses, nurse's aids and social workers) who play a role of prevention for intercurrent diseases, social and legal counselling and help anticipate the future. Multidisciplinary memory units are dedicated to the diagnosis and care of memory complaints and disorders. We describe here the operative function of these centers which should be integrated into a health care network centered around patients with memory complaints and their families.

[Lewy body dementia]

Dementia with Lewy Bodies (DLB) is an entity which now fulfils clinical and neuropathological criteria according to international consensus guidelines (McKeith et al., 1996). It is now possible, in clinical practice, to consider the diagnosis of DLB from the beginning of the management of a demented patient. The clinical, diagnostic and therapeutic aspects of DLB are investigated in a prospective manner. Visual hallucinations, fluctuations and extrapyramidal symptoms seem to have, in association with the progressive cognitive decline, some particularities. However their specificity should be correlated with neuropathological data. Other symptoms, such as repeated falls or syncope, neuroleptic sensitivity, systematized delusions or other modalities of hallucinations, are probably additional arguments giving more predictive value to the association of the major symptoms. The role of neuropsychological patterns at the beginning of the cognitive decline is shown. There are some recent concordant results of functional imaging in DLB. The neuropathological aspects of DLB and the links with Parkinson pathology and especially Alzheimer pathology are emphasized.

Effect of stabilising amino acids on the digestive absorption of heme and non-heme iron

We used the Ussing chamber model to study heme iron absorption by rat duodenal mucosa. Heme iron was obtained by enzymic digestion of bovine haemoglobin and concentration of heme (HPH). Its uptake and mucosal transfer was compared to iron gluconate (Gluc), at 100 microM and 1 mM. At 100 microM iron uptake (Qtot), mucosal retention (Qm) and transfer across the mucosa (Qs) was similar for the two sources of iron. Qs was significantly higher at 1 mM for Gluc but not for HPH, and was associated with higher levels of Qm. Addition of L-histidine did not improve iron absorption and indeed it decreased it if iron was provided as Gluc. L-cysteine increased the transfer of iron of both sources. In the in vitro model using rat digestive mucosa, heme iron appeared to be an efficiently used source of iron, which might prevent its accumulation by gut when supplied in excess.

Restricted and regulated overexpression reveals calcineurin as a key component in the transition from short-term to long-term memory

To investigate the roles phosphatases play in hippocampal-dependent memory, we studied transgenic mice overexpressing a truncated form of calcineurin. These mice have normal short-term memory but defective long-term memory evident on both a spatial task and on a visual recognition task, providing genetic evidence for the role of the rodent hippocampus in spatial and nonspatial memory. The defect in long-term memory could be fully rescued by increasing the number of training trials, suggesting that the mice have the capacity for long-term memory. We next analyzed mice overexpressing calcineurin in a regulated manner and found the memory defect is reversible and not due to a developmental abnormality. Our behavioral results suggest that calcineurin has a role in the transition from short- to long-term memory, which correlates with a novel intermediate phase of LTP.

Association between medial temporal lobe atrophy on CT and parietotemporal uptake decrease on SPECT in Alzheimer's disease

OBJECTIVES

Alzheimer's disease is the most frequent cause of degenerative dementia. Despite the available diagnostic criteria, improvement of diagnosic accuracy is still required. The aim of this prospective study was to assess in a large population of patients referred to a memory clinic the diagnostic value of the combination of medial temporal lobe atrophy on temporal oriented CT and decreased temporoparietal uptake on HMPAO single photon emission tomography (SPECT).

METHODS

The study was conducted in 125 patients aged 51-93: 64 with probable Alzheimer's disease (Mean (SD) mini mental state examination (MMSE)=18.34 (6.93)), duration of disease=6.48 (2.93) years, 13 possible Alzheimer's disease (MMSE=21.58 (5.48), duration of disease=6.08 (2.56)), 48 patients with miscellaneous memory disorders (MMSE=21.98 (6.10), duration the disease = 6.85 (3.91)).

RESULTS

For the diagnosis of probable Alzheimer's disease, the sensitivity of this association was 0.56, the specificity 0.93, the positive predictive value 0.95, and the negative predictive value 0.45. The diagnosic accuracy was 0.68. Both medial temporal atrophy and parietotemporal decrease in uptake were present in four of 13 patients with possible Alzheimer's disease and 11 of 48 with miscellaneous memory disorders. The association was absent in 27 of 29 patients with frontotemporal dementia. In mild stages (MMSE>18; n = 32), the sensitivity of the association was 0.34, the specificity 0.93, the positive predictive value 0.85, and the negative predictive value 0.57. The diagnosic accuracy was 0.53.

CONCLUSION

This association, although not sensitive, helps to select patients with high probability of Alzheimer's disease at an early stage which can be of interest for clinical and research purposes.

Preoperative pulmonary function tests do not predict outcome after coronary artery bypass

PURPOSE

To evaluate the utility of preoperative pulmonary function tests in predicting postoperative complications and lengths of stay after coronary artery bypass grafting.

METHODS

Medical records of 193 consecutive patients who underwent coronary artery bypass grafting from October 1993 to September 1994 were reviewed. Preoperative pulmonary function tests, comorbid conditions, smoking history, postoperative complications, and total days in the intensive care unit, hospital, and on mechanical ventilation were abstracted. Data were analyzed using linear regressions, analyses of variance, and nonpaired Student's t tests.

RESULTS

Pulmonary function tests were normal in 56 subjects (29%, group 1), mildly impaired in 72 (37%, group 2), and moderately impaired in 35 (18%, group 3). Thirty patients (16%) had no pulmonary function tests. Group 3 subjects were older (71) compared to groups 1 and 2 (63 and 65, P < 0.05). There was no major difference in comorbid conditions or smoking status among the groups. All patients had atelectasis postoperatively. The most frequent postoperative complications were pleural effusions (43%), pulmonary edema or congestive heart failure (28%), and atrial fibrillation (35%). The repeat surgery rate was 3.6%. The mean length of hospital stay was 10.1 +/- 0.6 days, with 1.5 +/- 0.1 days of mechanical ventilation and 2.8 +/- 0.2 days of intensive care unit stay. Overall, pulmonary function tests had no predictive value for postoperative pulmonary and nonpulmonary complications, nor for durations of mechanical ventilation and intensive care unit stay. There was a trend toward increased length of hospital stay in patients with impaired pulmonary function tests (group 18.6 +/- 0.6, group 2 9.6 +/- 0.8, group 312.7 +/- 2.3 days, P = 0.09) but this was consistent with random variation.

CONCLUSIONS

Preoperative pulmonary function tests were not useful in predicting postoperative outcomes in patients undergoing coronary artery bypass grafting.

Effects of a medical intensivist on patient care in a community teaching hospital

OBJECTIVE

To determine the effect of adding a trained intensivist on patient care and educational outcomes in a community teaching hospital.

MATERIAL AND METHODS

We retrospectively reviewed outcomes for patients admitted to the medical intensive-care unit (MICU) of a 270-bed community teaching hospital between July 1992 and June 1994. Mortality rates and durations of stay were determined for the year before (BD, 1992 through 1993) and the first year after (AD, 1993 through 1994) introduction of a full-time director of critical care. Performance of resident trainees on a standardized critical-care examination was measured for the same periods.

RESULTS

Overall, 459 patients in the BD period were compared with 471 patients in the AD period. The mix of cases and severity of illness (acute physiology and chronic health evaluation or APACHE II scores) on admission were similar for the BD and AD periods. MICU mortality decreased from 20.9% during the BD to 14.9% during the AD period (P = 0.02), and in-hospital mortality decreased from 34.0% to 24.6% (P = 0.002). Disease-specific mortalities were lower during the AD period for most categories of illness. Detailed analysis of a subgroup of patients (those with pneumonia) demonstrated no differences in distribution of patients by gender, race, or acuity of illness (APACHE II scores). The mortality rate due to pneumonia decreased from 46% during the BD period to 31% during the AD period. This decrease was consistent across categories of APACHE II scores. From BD to AD periods, mean durations of total hospital stay decreased from 22.6 +/- 1.4 days to 17.7 +/- 1.0 days, and mean MICU stay decreased from 5.0 +/- 0.3 days to 3.9 +/- 0.3 days (P < 0.05). Critical-care in-service examination scores for 22 residents increased from 53.8 +/- 1.7% to 67.5 +/- 2.2% (P < 0.01), and AD scores were significantly higher than BD scores for residents at similar levels of training.

CONCLUSION

Addition of a medical intensivist was temporally associated with improved clinical and educational outcomes in our community teaching hospital.

Medial temporal lobe atrophy in memory disorders

Medial temporal lobe atrophy determined by temporal lobe oriented computed tomography (CT), 1 year before death, is strongly associated with histopathologically confirmed Alzheimer's disease (AD). The aim of this study was to assess the diagnostic accuracy of medial temporal lobe measurement for the diagnosis of AD in patients referred to a memory disorders clinic, especially those at an early stage of the disease. CT oriented to the temporal lobe was performed in 333 subjects aged 41-93 years consecutively recruited in a Memory Disorders Clinic: 124 had probable AD, Mini Mental State score (MMS) = 17 (8); 50 possible AD [MMS = 21 (5)]; and 119 patients had miscellaneous memory disorders [MMS = 22 (7): frontotemporal lobe dementia, subcortical dementia, cortical Lewy body disease, vascular dementia, Korsakoff syndrome, focal atrophy, etc.]. There were also 19 anxious/depressed patients [MMS = 29 (1)] with normal performance on memory tests, and 21 controls. The minimum width of the medial temporal lobe was measured. The best cut-off to distinguish AD patients from non-AD patients was 11.5 mm, in agreement with data in the literature. At this threshold, 84% of probable AD patients had a positive test and 90% of controls and anxious/depressed patients had a negative test. For the diagnosis of probable AD, sensitivity of the measurement was 0.81, specificity 0.95, predictive positive value 0.99, predictive negative value 0.45, and diagnostic accuracy 0.83. The test was positive in half the possible AD patients, and half those with miscellaneous memory disorders. It was negative in all anxious/depressed patients. Therefore, temporal lobe oriented CT might be a valuable tool for assessment of medial temporal lobe atrophy in AD routine practice.

The use of SPECT in a multidisciplinary memory clinic

We tested the interobserver reliability of visual rating of HMPAO-SPECT imaging in 271 outpatients referred to a memory clinic, and followed over 1 year. The clinical diagnoses were Alzheimer's disease (n = 156), frontotemporal dementia (n = 47); vascular dementia (n = 21), senile dementia of Lewy body type (n = 12), anxiety/depressive disorders (n = 14) and miscellaneous memory disorders (n = 21). The interobserver agreement was good (k = 0.68). However, the heterogeneity of the patterns-independent from demographic data, age at onset and duration of the disease- and their lack of sensibility and specificity limited the contribution of SPECT for diagnostic purposes in routine practice.

The unassisted respiratory rate/tidal volume ratio accurately predicts weaning outcome in postoperative patients

OBJECTIVE

To evaluate the accuracies of the respiratory rate/tidal volume ratio (rate/volume ratio), minute volume, and negative inspired force in predicting weaning outcome in postoperative mechanically ventilated patients.

DESIGN

A prospective, observational study.

SETTING

Surgical intensive care unit of a 270-bed community teaching hospital.

PATIENTS

One hundred eighty-three postoperative, mechanically ventilated patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The spontaneous minute volume, unassisted respiratory rate/tidal volume ratio, and negative inspired force were measured just before weaning. The rate/volume ratio was remeasured after 30 to 60 mins of weaning. Weaning was conducted by the patients' primary physicians. Weaning success was defined as unassisted breathing for >24 hrs. Predictive characteristics were computed using threshold values of 100 breaths/min/L, 10 L/min, and -20 cm H2O for the rate/volume ratios, minute volume, and negative inspired force, respectively. Receiver operating characteristic curves were also constructed to assess each parameter. Sensitivities for the initial rate/volume ratio, rate/volume ratio after 30 mins, minute volume, and negative inspired force were 0.97, 0.96, 0.76, and 0.96, respectively. Specificities were 0.33, 0.31, 0.40, and 0.07, respectively. Areas (+/- SD) for receiver operating characteristic curves were 0.76 +/- 0.08, 0.75 +/- 0.06, 0.54 +/- 0.08, and 0.62 +/- 0.07, respectively. The rate/volume ratio after 30 mins correlated with the initial rate/volume ratio; the rate/volume ratio after 30 mins did not add significant, additional predictive information.

CONCLUSIONS

The rate/volume ratio measured at the beginning and after 30 mins of weaning is more highly predictive of weaning outcome than the negative inspired force and minute volume. The principal weakness of the rate/volume ratio is false-positive results.

Transcriptional pattern of Escherichia coli ihfB (himD) gene expression

Integration host factor (IHF) is a small heterodimer containing subunits encoded by the unlinked ihfA (himA) and ihfB (himD, hip) genes. The transcriptional pattern of ihfB expression in the logarithmic and stationary growth phases was investigated. The ihfB gene is expressed as both monocistronic and polycistronic (hybridizing also to an internal rpsA probe) transcript. The intensity of the polycistronic transcripts, initiated upstream of rpsA, decreased sharply upon growth cessation. In contrast, expression of the monocistronic ihfB transcript strongly increased when cells entered stationary growth phase. The observed growth rate-dependent regulation of the transcription of these transcripts is in agreement with the previously published data about the regulation of the rpsA and ihfB promoters (Pedersen et al., 1984; Aviv et al., 1994).

The unassisted respiratory rate-tidal volume ratio accurately predicts weaning outcome

PURPOSE

To assess the accuracies of four commonly used parameters in predicting weaning outcome and whether breathing pattern changes during weaning.

PATIENTS AND METHODS

We prospectively examined the predictive accuracies of four weaning parameters in mechanically ventilated patients in the medical and cardiac intensive care units of a 270-bed community teaching hospital. The spontaneous respiratory rate:tidal volume ratio (RVRi), negative inspiratory force (NIF), and spontaneous minute volume (VE) at the onset of weaning, and the RVR at 30 to 60 minutes of weaning (RVR30) were measured. Weaning decisions were made by patients' primary physicians independent of this study. Threshold values for computations of predictive values were as follows: RVR 100 < or = breaths per minute/L, NIF < or = -20 cm H2O, VE < or = 10 Lpm. Receiver operator curves were generated for each parameter.

RESULTS

One hundred medical/cardiac intensive care unit patients were studied. Their mean age was 64.6 +/- 15.8 years, mean APACHE II score of 15.8 +/- 6.7 and mean duration of mechanical ventilation before the study of 4.9 +/- 8.1 days. RVRi sensitivity was 89%, specificity was 41%, positive predictive value was 72%, negative predictive value was 68%, and accuracy was 71%. The RVR30 sensitivity was 98%, specificity was 59%, positive predictive value was 83%, negative predictive value was 94%, and accuracy was 85%. Accuracies for the NIF and VE were 66% and 62%, respectively. The area under the receiver operator curve of the RVR30 (0.92 +/- 0.03) was higher than the RVRi (0.74 +/- 0.05), NIF (0.68 +/- 0.06) and VE (0.54 +/- 0.06) (p < 0.05).

CONCLUSIONS

The RVR is more accurate than other commonly utilized clinical tools in predicting the outcome of weaning from mechanical ventilation. The RVR measured at 30 minutes is superior to the RVR in the first minute of weaning. The predictive accuracy and unique simplicity of the RVR justify its use in the care of mechanically ventilated patients.

Cardiac ischemia during weaning from mechanical ventilation

In this prospective study, we measured the ST segments, heart rate-systolic BP product (RPP), respiratory rate to tidal volume ratio (RVR), and pulse oximetry saturations of patients in our medical/cardiac ICUs before and during weaning from mechanical ventilation. Ninety-three patients were enrolled with a mean age of 66.5 +/- 15.0 years (mean +/- SD), mean acute physiology and chronic health evaluation (APACHE) II score of 16.0 +/- 6.9, and mean duration of mechanical ventilation of 5.2 +/- 8.6 days. Forty-nine patients had coronary artery disease (CAD). Six of 93 patients (6.4%) experienced ECG evidence of ischemia during weaning. Five of these six had a precedent history of CAD and four failed initial weaning attempts (22% of patients with CAD who failed weaning). The RPP, for the group as a whole, increased significantly during weaning from 12.0 +/- 3.1 to 13.4 +/- 4.0 mm Hg.bpm.10(3) (p<0.01). The rate to volume ratio did not change significantly during weaning, except in the subgroup of patients who failed to wean, in whom it increased from 98.4 +/- 45.2 to 124.9 +/- 54.9 bpm/L (p<0.05). Oxygenation also decreased significantly from 0.98 +/- 0.02 to 0.96 +/- 0.03 and was significantly associated with weaning failure (risk ratio [RR]=3.9; 95% confidence interval [CI]=1.7 to 9.0). Thirty-seven patients failed the initial weaning attempt. Cardiac ischemia (RR= 1.8; 95% CI=1.0 to 3.4) and an increased RVR (RR=1.7; 95% CI=0.9 to 3.4) tended to increase the risk of weaning failure. Cardiac ischemia, although infrequent (6%) in the general population of weaning medical/cardiac ICU patients, should be considered in patients with CAD who fail to wean.

[The influence of cations on the letality and on the formation of the toxin of Pasteurella multocida]

The stability of the Pasteurella multocida toxin has proven as very pH dependent. Therefore, a pH lower than 6 should be avoided. A concentration of 1 mM Cu2+ decreased the lethal effect of the toxin but the equimolecular addition of chelators compensated this effect. Possible structure-effect mechanisms were discussed. Iron supplement (100 microM) to two culture media examined did not influence the production of the toxin but during the cultivation in the low-iron medium TDHM the toxin level increased. This increased toxin production was not due to a more intensive multiplication of bacteria.

Achondrogenesis type IB (Fraccaro): study of collagen in the tissue and in chondrocytes cultured in agarose

A lethal chondrodysplasia characterized by extreme micromelia was diagnosed by ultrasound examination in two sibs whose nonconsanguineous parents were healthy. Radiographic and histopathologic data indicated that the two foetuses (18 and 21 weeks old) had achondrogenesis type IB (Fraccaro). Quantitation of total collagen extractable from dried cartilage samples demonstrated a 50% decrease when compared to an age-related control. This decrease was essentially related to type II collagen. Nevertheless, the alpha chains and the CB peptides of type II collagen had a normal electrophoretic mobility. A significant amount of collagen type I was also detected. The electrophoretic pattern of collagens type IX and XI did not differ significantly from control sample. The extracellular matrix elaborated by patient chondrocytes cultured in agarose for 10-12 days, contained less collagen type II than normal cells. Labelling with 14C-proline of cultured cells showed the presence of procollagen and type II collagen chains with a normal electrophoretic mobility, but an alpha 2(I) chain was detectable in the patient material, indicating the presence of collagen type I which supported the tissue findings. The significance of the type II collagen reduction in the patient's cartilage is unclear but it is unlikely to be the primary defect in achondrogenesis type I.