Continuum model of mnemonic and amnesic phenomena

Amnesia in its various forms is characterized by defects in one or more components of a complex system. Implantation of short-term memory occurs in the hippocampus, while long-term memory is essentially located in the neocortex; these regions are interconnected through complex synaptic structures. In the hippocampus, physiological data show that, as predicted by Hebb, excitatory synapses between nearby excitatory cells become strengthened by simultaneous activation. In contrast with this local process, the preponderance of clinical and experimental evidence indicates that cortical recall of a "memory" is the reconstruction of fragments stored in different synaptically distant brain regions. A mathematical model of memory must reconcile this apparent contradiction as well as explain how many different memories and "ideas" can be assembled within a given anatomical area. Continuum theory, which treats an ensemble of "cell assemblies" or neural networks, offers a step in this direction. Linear analysis using this approach shows that it is the nature of the neural continuum to generate activity waves of wavelength greater than synaptic connection ranges. These waves grow under certain circumstances, and their wavelength is controlled by the synaptic parameters. Both hippocampal and cortical tissue are subject to such wave growth. In the hippocampus, the local Hebbian strengthening controls the global wave growth, making the difference between wave decay and growth. The cortical wave structure can become very complex, so that reproducible memory recall as well as "creative thought" can be accommodated in the theory. Deficits in the functioning of the system may also be evaluated potentially by means of "goodness-of-fit" of the clinical and spatially resolved data with the model.

Numbers, models, and understanding of natural intelligence: computational neuroscience in the service of clinical neuropsychology

What we call computational neuroscience involves construction of mathematical and numerical models for understanding cognitive phenomena. This issue is devoted to showing how it can also be used to help in the analysis of cognitive defects. Although the models may seem abstract to clinicians, they are based on the reality of brain anatomy. The theoretical papers presented here are connectionist: They posit a network of cells connected by synapses whose weights are modified during learning. Architecture of connectionist models has progressed and ramified considerably since they were first introduced, and we include some examples of the current state of the art. The final work presented here is concerned with the connection of the constructed models with clinical experience and experiment.

First experimental and clinical results with transscleral optical coherence tomography

BACKGROUND AND OBJECTIVE

To evaluate the potentials of optical coherence tomagraphy (OCT) using long wavelength to penetrate highly scattering tissues of the eye and visualize the anterior chamber angle and the ciliary body.

METHODS

OCT images were generated by an experimental prototype in enucleated porcine eyes using as light source a superluminiscent diode with a wavelength of 1310 nm and a scan frequency of 60 Hz. The number of lateral scans was variable in a range from 100 to 400.

RESULTS

Infrared OCT was able to penetrate the sclera. The anterior chamber angle could be visualized completely and the ciliary body could be identified. However, it was not possible to penetrate the highly reflective iris pigment epithelium.

CONCLUSION

The use of infrared OCT allows penetration of the sclera, thus, providing complete visualization of the anterior chamber angle and limited demonstration of the ciliary body. Because of its higher resolution, it may represent an interesting noninvasive alternative to ultrasound biomicroscopy.

Delayed-type hypersensitivity skin reactions caused by subcutaneous unfractionated and low-molecular-weight heparins: tolerance of a new recombinant hirudin

BACKGROUND

Eczema-like infiltrated plaques at subcutaneous heparin injection sites are well-documented side effects of these anticoagulants. However, surgical interventions may be problematic if heparin is urgently needed in these patients.

OBJECTIVE

The aims of this study were to perform extensive allergy skin testing in 24 patients, including a pregnant woman in whom subcutaneous infiltrated plaques developed after subcutaneous heparin injections, and to find safe therapeutic alternatives for this group of patients.

METHODS

Patch, intradermal, and subcutaneous tests were performed with a panel of unfractionated heparins (UFHs), low-molecular-weight heparins (LMWHs), and heparinoids. Since 1997, we have also been performing allergy studies in 8 patients with lepirudin, a new recombinant heparinoid; tolerance of lepirudin was investigated by means of subcutaneous and intravenous injections. The allergy investigations in the pregnant woman were limited to patch tests with heparins and intradermal and subcutaneous tests with pentosanpolysulfate, which are not contraindicated during pregnancy.

RESULTS

In our study population 19 of 23 patients were sensitized to all the UFHs and LMWHs tested when intracutaneous and subcutaneous test results were read at up to 96 hours. LMWH was found to be a possible substitute in 4 patients. Five patients were also sensitized to the heparinoid pentosanpolysulfate. Sensitization to the heparinoid danaparoid was observed in 12 of the 13 patients who were tested with this substance. The administration of an intravenous bolus containing a therapeutic dose of lepirudin after negative subcutaneous provocation was tolerated without any side effects in all 8 patients. The pregnant woman was sensitized to LMWH but tolerated subcutaneous pentosanpolysulfate without any side effects.

CONCLUSION

Extensive allergy skin testing should be performed to find safe alternatives. With few exceptions, all patients react to both UFHs and LMWHs, as well as to danaparoid. The subcutaneous provocation test is the most reliable diagnostic measure. Intravenous lepirudin, and in some cases subcutaneous pentosanpolysulfate, appears to be a safe alternative in patients with eczema-like infiltrated plaques at subcutaneous heparin-injection sites.

Tumor-derived mutations within the DNA-binding domain of p53 that phenotypically resemble the deletion of the proline-rich domain

The p53 tumor suppressor protein induces apoptosis through a mechanism that may involve the transcriptional activation of cellular genes, including the PIG3 gene. A p53 protein lacking the proline-rich region (p53delta62-91) induces many p53-responsive genes but not PIG3. In parallel, this mutant induces growth arrest but not apoptosis. We show here that the replacement of the N-terminal (amino acids 1-80) or C-terminal (amino acids 344-393) domains of p53 with heterologous domains does not interfere with transcription from the PIG3 promoter, but these chimeras still require the proline-rich region for PIG3 activation. The p53-homolog p73beta also activated the PIG3 promoter, but in contrast to p53, the proline-rich domain of p73beta (residues 81-113) was dispensable to induce the PIG3 promoter. Some tumor-derived p53-mutants, especially M246I, retained the ability to activate transcription of mdm2 but specifically failed to induce the PIG3 promoter, thus resembling p53delta62-91. Further, p53delta62-91 and p53M246I were defective for induction of apoptosis. Finally, p53delta62-91 and p53M246I both showed reduced binding to the DNA of the PIG3 promoter and also to the DNA of the mdm2 and p21 promoters in vitro. Correspondingly, at low expression levels, p53delta62-91 and p53M246I poorly activated the mdm2 promoter when compared to wild type p53. Our results suggest that the proline-rich domain of p53 affects the ability of the central domain to bind DNA. Moreover, some tumor-derived mutations within the central DNA binding domain of p53 mimic the loss of the proline-rich domain.

Operative and conservative management of primary gastric lymphoma: interim results of a German multicenter study

PURPOSE/OBJECTIVE

Biology and appropriate management of gastrointestinal (GI lymphomas are matters of an ongoing controversial debate. To evaluate histological features, sites of involvement and management of primary GI-lymphomas, a prospective multicentric study was initiated in 10/1992. Aim of study was the further standardization of operative and conservative treatment modalities.

MATERIALS AND METHODS

Study started 10/1992 and was closed 11/1996. A total of 381 evaluable patients had been accrued then. Standardized diagnostic workup included endoscopic and radiological evaluation of the complete GI-tract as well as a central histological review. Diagnosis was established after Lewin, stage classification was made after Musshoff, and histological classification was made after Isaacson. Treatment decision concerning operative or conservative management was due to the initially acting physician. Patients with resection of low grade lymphoma received total abdominal irradiation 30 Gy + 10 Gy boost to incompletely resected areas. After resection of high grade lymphoma CHOP chemotherapy (4 cycles for stage IE, 6 cycles for higher stages) after McKelvy was followed by total abdominal irradiation 30 Gy for stage IE respectively involved field irradiation 30 Gy for higher stages with 10 Gy boost to incompletely resected areas. Primary conservative- treatment consisted of six cycles COP chemotherapy after Bagley for low grade lymphomas stage > IE and total abdominal irradiation 30 Gy + 10 Gy boost to involved areas for all stages. Patients with high grade lymphomas received 4 x CHOP followed by total abdominal irradiation 30 Gy + 10 Gy boost to involved areas or 6 x CHOP plus involved field radiation therapy with 40 Gy. 257 patients are considered for analysis due to exclusion criteria of the study, 190 of them were suffered from gastric lymphoma. Their median observation time is 29 months, maximum observation time is 68 months.

RESULTS

Sites of involvement were stomach in 73.4%, small bowel 9.6%, ileocoecal region 6.9%, and other sites 3.2% More than one GI site was involved in 6.9%. Gastric lymphomas achieved a survival probability of 89% after 3 years. Though surgical and conservative treatment was not randomized, outcome was analyzed in gastric NHL stages I and II (histologic subtype not considered showing no significant influence). At 3 and 5 years survival is 88% in resected cases vs. 94% and 86% in conservatively treated patients (p = 0.350). Analyzing only stages I + II(1) surgery also seems of no advantage even considering only RO-resections. There was one acute gastrointestinal bleeding under primary chemotherapy for a high grade lymphoma. Toxicities of grade III and IV WHO were rarely seen during treatment. All other acute toxicities were not more than grade II WHO.

CONCLUSION

Conservative treatment in this setting is feasible. The operative approach seems not to be advantageous compared to conservative treatment and should be critically reconsidered.

Slit-lamp-adapted optical coherence tomography of the anterior segment

PURPOSE

To evaluate the diagnostic potential of a slit-lamp-adapted optical coherence tomography (OCT) system as an in vivo imaging device for routine clinical examination of the anterior segment of the eye.

PATIENTS AND METHODS

In a pilot study, healthy volunteers and patients with different pathologies of the anterior segment were examined with a slit-lamp-adapted OCT system using 100-200 axial scans with 100-Hz line-scan frequency. The scan length is variable up to 7 mm, and the axial depth is 1.5 mm in tissue.

RESULTS

The slit-lamp-adapted OCT system allowed direct biomicroscopic imaging of the measured area. Anatomic structures and morphological changes anterior to the attenuating iris pigment epithelium could be visualized with high accuracy. Biometric analyses of the cornea, the chamber angle, the iris and secondary cataract were possible. Complete demonstration of the chamber angle was difficult due to the backscattering properties of the anterior part of the sclera and the consequent shadowing of the most peripheral part of the iris.

CONCLUSIONS

Slit-lamp-adapted OCT is a useful diagnostic tool which allows in vivo microscopic cross-sectional imaging of the anterior segment and precise measurement of ocular structures.

Pharmacokinetics and pharmacodynamics of cumulative single doses of inhaled salbutamol enantiomers in asthmatic subjects

Objectives of this study were to compare the pharmacokinetics, pharmacodynamics and safety of single cumulative doses of active (R)-salbutamol given either as the single enantiomer or racemic mixture by inhalation to subjects with mild to moderate asthma. This was a double-blind, crossover, cumulative-dose, randomized study where all subjects received either four doses of 1.25 mg of (R)-salbutamol or 2.5 mg of racemic (RS-) salbutamol by nebulization. The pharmacokinetic parameters were determined by noncompartmental analysis and model-fitting. Changes in FEV(1), plasma potassium, plasma glucose, heart rate, and QTc interval were measured. The potassium and glucose data were fitted to indirect response pharmacodynamic models. The heart rate and QTc data were evaluated using data descriptors. No significant differences in pharmacokinetics of (R)-salbutamol given as either (R)- or (RS)-salbutamol were found with AUC values of 11.90 +/- 4.37 and 11. 47 +/- 2.88 ng.h/ml. The t(max)of about 2 h reflected serial dosing rather than delayed absorption. The t(1/2)averaged about 3.5 h. The (S)-salbutamol showed AUC of 48.46 +/- 12.11 ng.h/ml with a t(1/2)of about 5 h. The changes in FEV(1)reached a plateau after an initial increase and did not return to pre-drug values for 10 h. All pharmacodynamic parameters were similar whether (R)- or (RS)-salbutamol was given. The exposure to (R)-salbutamol was identical after inhalation of (R) -and (RS)-salbutamol by subjects with asthma. Several pharmacological responses including FEV(1)were also similar and there were no unique safety concerns with either treatment.

Analysis of failures after whole abdominal irradiation in gastrointestinal lymphomas. Is prophylactic irradiation of inguinal lymph nodes required? German Multicenter Study Group on GI-NHL, University of Muenster

BACKGROUND

To evaluate failures and to investigate the need for prophylactic inclusion of the inguinal lymph nodes in case of whole abdominal irradiation in gastrointestinal lymphoma.

PATIENTS AND METHOD

In October 1992 a prospective study on primary gastrointestinal lymphoma was initiated to evaluate management strategies. Treatment consisted either of conservative management comprehending radiotherapy +/- chemotherapy or radio-/chemotherapy sequential to primary surgery, depending on the physician's decision. Until November 1996, 382 patients were enrolled. Out of them we analyzed 92 patients who received a whole abdominal irradiation, in 21 cases with prophylactic inclusion, in 71 cases without inclusion of inguinal lymph nodes.

RESULTS

After a median follow-up time of 36 months in 92 patients with whole abdominal irradiation 9 patients developed relapse of gastrointestinal lymphoma (8 local failures, 1 distant failure). In these cases the analysis of radiation therapy shows low tumor doses or small field sizes. No significant difference in the relapse rates is shown between the 21 patients with inclusion of the inguinal lymph nodes in the abdominal radiation fields (3 recurrences approximately equal to 14.3%) and the 71 patients without enclosure of the inguinal lymph nodes (6 recurrences approximately equal to 8.5%).

CONCLUSION

General prophylactic enclosure of the inguinal lymph nodes in the case of whole abdominal irradiation in gastrointestinal lymphoma seems to be unnecessary.

The radio-radial external fixator in the treatment of fractures of the distal radius

The technique of radio-radial monobloc-fixation with the small AO external fixator device has been applied to 17 consecutive Colles' fractures. The fracture types were mainly A3 and C2, according to the AO classification. We found this technique to be easy and quick in application and stable in fixation. Direct, precise and atraumatic reduction can be achieved by using the distal pins as joy-sticks. Furthermore, disimpaction of the fracture to regain length is possible without bone grafting. Normal carpal mobility and load transfer is preserved during fracture healing and the injured hand can be used in daily life with certain restrictions. To prevent pin-track infections, early mobilization of the wrist should be avoided. We recommend this technique in the treatment of comminuted AO-type A3 fractures of the distal radius and in certain type C2 cases.

Oral lesions and symptoms related to metals used in dental restorations: a clinical, allergological, and histologic study

BACKGROUND

Allergy to mercury as a cause of oral lichenoid lesions (OLL) remains controversial. Some authors reported high frequency of sensitization to mercury and beneficial effect from removal of amalgam fillings in such patients, whereas others state that this procedure affects favorably all OLL, whether patients are sensitized to inorganic mercury or not.

OBJECTIVE

Our purpose was to determine the frequency of sensitization to metal salts in 194 patients (patients with OLL partly adjacent to amalgam fillings: 19, oral lichen planus (OLP) without close contact to amalgam: 42, other oral diseases: 28, oral complaints: 46, control group: 59). We further studied the histologic changes of biopsy specimens from positive patch tests to metal salts, and investigated the effect of removal of amalgam in OLL, to clarify whether it is possible to identify patients who will benefit from this procedure.

METHODS

Patch testing was performed with the German standard series, a dental prosthesis series, and a metal salt series including gold, mercury, and palladium salts as well as other salts of metals used in dental restorations. Late readings (10 and 17 days after application of the patch tests) were performed in all patients.

RESULTS

Of 19 patients with OLL adjacent to amalgam fillings, 15 (78.9%) were sensitized to inorganic mercury (INM), significantly more than those with OLL not adjacent to amalgam, other oral diseases or complaints, and the control group. In 5 of 15 (33.3%) of the patients with OLL, a positive patch test to INM was observed only at D10 or D17. Amalgam was removed in 18 patients with OLL (sensitization to INM: 15), and in 11 patients with OLP (sensitization to INM: 2). After removal, the lesions of 13 of 15 of the INM-sensitized patients with OLL (86. 7%) and 2 with OLP healed or improved significantly, but this was not observed with the INM negative patients. Frequency of sensitization to gold sodium thiosulfate (GST) and palladium chloride 1% pet (PDC) was high in all groups. This was partly because readings were performed late. Lesions of 2 patients with allergic contact stomatitis caused by gold and 1 caused by palladium healed completely after removal of these restorations. Histologically, lichenoid changes were observed in 14 of 36 biopsy specimens of positive patch tests from INM (9/21), GST (2/10), and PDC (3/5) in all patient groups, mainly in persistent patch tests at D10 or D17. This was not observed in 12 biopsy specimens taken from persistent patch tests from other substances, including nickel sulfate.

CONCLUSION

Our results suggest that sensitization to mercury is an important cause of OLL, whether all lesions or only a part of them are adjacent to amalgam fillings. Sensitization to GST may reflect true gold allergy and should be considered as a cause of oral diseases in some patients. Sensitization to PDC is frequent but has yet only little clinical relevance. Patch tests may be positive only at D10 or D17. This suggests the importance of additional readings of GST, PDC, and mercury salts at this time.

Results of a randomized double-blind placebo-controlled trial evaluating sequential high-dose cytosine arabinoside/mitoxantrone chemotherapy with or without granulocyte/macrophage-colony-stimulating factor in high-risk myelodysplastic syndromes

A prospective, randomized, double-blind placebo-controlled trial was designed to evaluate the impact of granulocyte/macrophage-colony-stimulating factor (GM-CSF) on the efficacy of sequential high-dose cytosine arabinoside/mitoxantrone chemotherapy (S-HAM) in adult patients with high-risk myelodysplastic syndromes (MDS). GM-CSF or placebo was given subcutaneously once daily at a dose of 250 microg/m2, starting 48 h prior to chemotherapy, and continued until neutrophil recovery. Owing to high toxicity and slow patient recruitement the study was closed and unblinded after 31 patients had been enrolled; 15 were randomized to receive placebo and 16 to receive GM-CSF. A total of 29 patients were evaluable for response; their median age was 57 years. Ten patients achieved a complete remission (34.5%), 9 patients had persistent MDS (31%), 10 patients died within 6 weeks after the onset of treatment (early death) (34.5%). The median remission duration was 190 days (range: 2.5-45 months). Among the 29 evaluable patients no significant differences could be found between the two study arms regarding complete remission rate [GM-CSF: 31% (5/16) versus placebo: 38% (5/13) P = 0.45], rate of persistent MDS [GM-CSF: 25% (4/16) versus 38% (5/13) P = 0.35), early death rate [44% (7/16) versus 23% (3/13) P = 0.22] and remission duration (GM-CSF: 87 days versus placebo 221 days). Duration of granulocytopenia (median: 33 days with GM-CSF) versus 35 days with placebo) and frequency of infectious episodes were not significantly influenced by GM-CSF. The small number of patients finally analyzed means that no definite conclusions about the effect of GM-CSF can be reached.

Moderate dose escalation for advanced stage Hodgkin's disease using the bleomycin, etoposide, adriamycin, cyclophosphamide, vincristine, procarbazine, and prednisone scheme and adjuvant radiotherapy: a study of the German Hodgkin's Lymphoma Study Group

The BEACOPP (bleomycin, etoposide, adriamycin, cyclophosphamide, vincristine, procarbazine, and prednisone) regimen, a rearranged and accelerated version of the standard COPP/adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD) chemotherapy, has been shown to be effective and safe in a previous pilot study for advanced stage Hodgkin's disease (HD). The present study aimed to determine a maximum practicable dose of three drugs, ie, etoposide, adriamycin, and cyclophosphamide, for which acute toxicities were acceptable and to assess the feasibility of the escalated scheme. Sixty untreated patients with advanced stage HD were enrolled in this study. Radiotherapy was given in 44 patients (73%) after chemotherapy to initial bulk lesions and residual disease. Granulocyte-colony stimulating factor (G-CSF) was given from day 8 to prevent prolonged neutrocytopenia and severe infections. The intended doses of adriamycin, etoposide, and cyclophosphamide in the BEACOPP schedule could be substantially escalated: adriamycin from 25 to 35, cyclophosphamide from 650 to 1,200, and etoposide from 100 to 200 mg/m2. The major toxicities were leukocytopenia and thrombocytopenia with considerable heterogeneity between individual patients. Of 60 patients, 56 (93%) achieved a complete remission (CR). At a median observation of 32 months, the rates of survival and freedom from treatment failure (FFTF) were estimated to be 91% (95% confidence interval 83% to 99%) and 90% (82% to 98%). These results show that a moderate dose escalation of adriamycin, cyclophosphamide, and etoposide of the baseline BEACOPP regimen is feasible. The escalated BEACOPP regimen shows very encouraging results in advanced stage HD and is now being compared in a randomized phase III study with BEACOPP at baseline dose level.

Pharmacokinetic and pharmacodynamic characteristics and safety of inhaled albuterol enantiomers in healthy volunteers

The pharmacokinetics and pharmacodynamics of inhaled albuterol given as single or multiple doses of racemate (RS-) or single enantiomers (R-, S-) were determined. In an open-label, three-way crossover, parallel-dose study, 1.25 and 5 mg of (R)- and (S)-albuterol and 2.5 and 10 mg of (RS)-albuterol were given via nebulization to 15 healthy volunteers. The pharmacokinetic parameters of each enantiomer were determined by noncompartmental and model-fitting analyses. Both (R)- and (S)-albuterol showed rapid absorption and biexponential decline, with half-lives (t1/2) averaging 4 and 6 hours, respectively. There were no differences in pharmacokinetics of (R)-albuterol when administered as (R)- or (RS)-albuterol at the 5-mg dose with equivalent relative bioavailability as seen from maximum concentration (Cmax) and area under the concentration-time curve (AUC). The same was true for (S)-albuterol at the 1.25-mg and 5-mg doses. The data from 5-mg doses were considered to be more reliable due to assay sensitivity limitations, and indicated equivalent absorption and disposition of the individual enantiomers. There was no evidence of in vivo racemization, and (R)-albuterol did not interconvert to (S)-albuterol. Plasma potassium, plasma glucose, heart rate, and QTc interval were used in linear and Emax models to assess responses relating to (R)-albuterol concentrations. The Emax for potassium change was 1.32 meq/L, with an EC50 of 0.59 and 0.94 ng/mL after administration of (R)- and (RS)-albuterol, respectively. The slopes and intercepts for glucose and heart rate changes were similar after administration of (R)- and (RS)-albuterol. No concentration-effect relationships were evident for QTc interval or for (S)-albuterol. The extrapulmonary responses of (R)-albuterol and adverse effects were similar for single R-enantiomer or the racemic mixture.

Intercellular trafficking of VP22-GFP fusion proteins is not observed in cultured mammalian cells

Herpes simplex virus type 1 (HSV-1) VP22 was recently reported to mediate intercellular trafficking of a protein fused to the C-terminus of VP22. To explore the application of such trafficking, we constructed plasmids expressing green fluorescent protein (GFP) fused to the C-terminus of either wild-type VP22 or a 160 amino acid peptide from VP22. In vitro studies showed that the majority of both fused proteins were localized to the nuclei of transfected cells. Quantitative analysis of GFP-positive cells, however, showed no significant increase in intercellular protein trafficking for cells transfected with either fusion protein compared with a lacZ-expressing plasmid. Our results suggest that the use of HSV-1 VP22 for mediating intercellular trafficking of transgene products is limited.

Determination of the enantiomers of albuterol in human and canine plasma by enantioselective high-performance liquid chromatography on a teicoplanin-based chiral stationary phase

A sensitive enantioselective high-performance chromatographic (HPLC) method was developed validated to determine low levels of (-)-R and (+)-S-albuterol in plasma. Baseline resolution was achieved by using a teicoplanin-based chiral stationary phase with a polar organic mobile phase consisting of methanol/ acetonitrile/glacial acetic acid/diethylamine, 40:60:0.3:0.2, (v/v/v/v) and a flow-rate of 1.0 ml/min. Enantioselectivity (alpha) equaled 1.18 and resolution (RS) equaled 1.8. By using fluorescence detection maximized at 230 and 310 nm for excitation and emission, respectively, concentrations of each enantiomer could be measured down to 125 pg/ml from a 1-ml plasma sample. Initially, the method was applied to plasma samples from a small single-dose inhalation study of racemic albuterol in a human volunteer and, later, to in vivo samples from a canine inhalation study of the single enantiomer, (-)-R-albuterol. Results from the canine study showed that no chiral inversion of (-)-R-albuterol occurs in the dog.

[Skin burns, necrosis and ulcers caused by wet cement, ready-mixed concrete and lime. 8 cases]

INTRODUCTION

Skin burns and caustic ulcers caused by wet cement, due to calcium hydroxyde, are rarely reported in the literature. They occur mostly among amateur cement users.

OBSERVATIONS

We report seven cases of skin burns, necrosis and ulcerations after use of wet cement and ready-mixed concrete, and one case of caustic ulcers induced by wet lime.

CONCLUSION

Even short skin contacts to wet cement or concrete may induce extensive lesions in some cases. However, we were not able to incriminate with certainty any special concrete additives which could increase skin penetration of calcium hydroxyde. Warning notices about the danger of skin contact should be prominent on sacked cement. When ready-mixed concrete is delivered, the purchaser should be handed a note explaining the risk of kneeling in wet concrete and the importance of protective measures. This may probably contribute to reduce the frequency of those accidents.

Genotype and phenotype of N-acetyltransferase 2 (NAT2) polymorphism in patients with contact allergy

We investigated whether patients with contact allergy differed from non-contact-allergic, non-atopic controls with regard to genotype and phenotype of the polymorphic enzyme N-acetyltransferase 2 (NAT2). 55 contact-allergic patients recruited from the Information Network of Departments of Dermatology (IVDK) were compared to 85 controls from among local health care personnel. NAT2 activity was calculated from HPLC analysis of the ratio of the caffeine metabolites 5-acetylamino-6-formylamino-3-methyluracil (AFMU) and 1-methylxanthine (1MX) in the urine. NAT2 genotype was determined by polymerase chain reaction (PCR). A statistically significantly increased proportion of rapid acetylators was found in contact-allergic patients. This may have 2 possible implications: acetylation may enhance contact sensitization; or NAT2 status may be a genetic marker for contact sensitizability.

Natural abundance variations in stable isotopes and their potential uses in animal physiological ecology

Chemical, biological, and physical processes lead to distinctive "isotopic signatures" in biological materials that allow tracing of the origins of organic substances. Isotopic variation has been extensively used by plant physiological ecologists and by paleontologists, and recently ecologists have adopted the use of stable isotopes to measure ecosystem patterns and processes. To date, animal physiological ecologists have made minimal use of naturally occurring stable isotopes as tracers. Here we provide a review of the current and potential uses of naturally occurring stable isotopes in animal physiological ecology. We outline the physical and biological processes that lead to variation in isotopic abundance in plants and animals. We summarize current uses in animal physiological ecology (diet reconstruction and animal movement patterns), and suggest areas of research where the use of stable isotopes can be fruitful (protein balance and turnover and the allocation of dietary nutrients). We argue that animal physiological ecologists can benefit from including the measurement of naturally occurring stable isotopes in their battery of techniques. We also argue that animal physiologists can make an important contribution to the emerging field of stable isotopes in biology by testing experimentally the plethora of assumptions upon which the techniques rely.