Preparation of highly accessible mordenite coatings on ceramic monoliths at loadings exceeding 50% by weight

A mordenite layer with a high accessibility has been synthesised on cordierite monolith supports; substantial loadings of mordenite were achieved (above 50 wt%) under the synthesis conditions used.

Scaling of the interface roughness in Fe-Cr superlattices: self-affine versus non-self-affine

We have analyzed kinetic roughening in Fe-Cr superlattices by energy-filtered transmission electron microscopy. The direct access to individual interfaces provides both static and dynamic roughness exponents. We find an anomalous non-self-affine scaling of the interface roughness with a time dependent local roughness at short length scales. While the deposition conditions affect strongly the long-range dynamics, the anomalous short-range exponent remains unchanged. The different short- and long-range dynamics outline the importance of long-range interactions in kinetic roughening.

Cytological and microbiological findings in guttural pouch lavages of clinically normal horses with head restraint

OBJECTIVE

To evaluate the cytological and microbiological contents of guttural pouch washes of ten randomly selected horses restrained so as to prevent them lowering their heads, and to assess the possible effects on the guttural pouch environment in these horses.

PROCEDURE

Cytological and microbiological studies were performed on guttural pouch washes of ten clinically normal horses restrained in a standing position so as to prevent them from lowering their heads below normal, as would happen during transportation on long journeys. They were restrained for 12 or 24 h and cytological, bacteriological and mycological findings in guttural pouch washes were recorded.

RESULTS

The cytological gradings and neutrophil concentrations of guttural pouch washings were higher in horses that had their heads restrained for a longer period. Washings from these horses were more likely to contain cultivable bacteria and were the only washes yielding potentially pathogenic bacterial species.

CONCLUSION

Variation in the cytological differential counts and bacterial cultures of guttural pouch lavages may be found in clinically normal horses which have had their heads restrained in an elevated position for periods from 12 to 24 h. This should be considered when examining this site and care must be taken when interpreting cytology of guttural pouch lavages in samples taken after transportation for more than 12 h. Restriction of head movement could also affect the normal pouch enviroment and predispose it to disease.

Nonconvulsive status epilepticus associated with cephalosporins in patients with renal failure

PURPOSE

Nonconvulsive status epilepticus is an unusual complication of cephalosporin therapy, with only a few isolated cases reported.

SUBJECTS AND METHODS

We reviewed the clinical and electroencephalographic (EEG) characteristics of 10 patients with renal failure in whom developed alteration of consciousness without convulsions associated with continuous epileptiform EEG activity while being treated with cephalosporins.

RESULTS

Nonconvulsive status epilepticus developed in 5 men and 5 women, with a mean (+/- SD) age of 69 +/- 14 years, while receiving intravenous cephalosporins (ceftriaxone, 2 patients; ceftazidime, 2; and cefepime, 6). All patients had renal failure; 1 also had hepatic failure. Patients presented with progressive disorientation or agitation, sometimes associated with mild facial or limb myoclonus, that had begun 1 to 10 days (mean, 5 +/- 2 days) after starting cephalosporin treatment. The EEG showed continuous or intermittent bursts of generalized, high-voltage, 1 to 2 Hz sharp wave activity or sharp and slow wave activity that resembled, but could be differentiated from, the triphasic waves seen in metabolic encephalopathies. Intravenous clonazepam suppressed the epileptiform activity completely in 5 patients and partially in the other 5. Cephalosporins were withdrawn, and antiepileptic therapy was started for all patients. All patients improved, 2 in less than 24 hours and the remainder within 2 to 7 days.

CONCLUSIONS

Cephalosporins can cause nonconvulsive status epilepticus in patients with renal failure. The clinical picture is difficult to differentiate from a that of metabolic encephalopathy unless an EEG is obtained. Physicians should be aware of this potentially dangerous complication.

Blood loss in elective coronary artery surgery: a comparison of centrifugal versus roller pump heads during cardiopulmonary bypass

OBJECTIVES

To compare the effects of centrifugal pumps versus roller pumps for cardiopulmonary bypass (CPB) in routine cardiac surgery on hematologic parameters in the context of modern practice.

DESIGN

Prospective, randomized, partially blinded.

SETTING

University teaching hospital.

PARTICIPANTS

Elective coronary artery surgery patients (n = 113)

INTERVENTION

Patients were randomized to be perfused with either a roller head (group R, n = 56) or a centrifugal head (group C, n = 57) pump. Patients received epsilon-aminocaproic acid before and during CPB. Core body temperatures were allowed to drift down to approximately 32 degrees C.

MEASUREMENTS AND MAIN RESULTS

Postoperative chest tube blood loss, blood product requirements, hemoglobin, and platelet counts were assessed. There were no significant differences in preoperative or intraoperative parameters, including CPB time, complexity of procedure, and minimum core temperature. There were the expected reductions in hemoglobin and platelet levels post-CPB in both groups to a similar extent. Chest tubes remained in situ for similar durations, and the final volume of drainage was not significantly different (group C, 1300 +/- 92 mL; group R 1117 +/- 83 mL; p = 0.14). Allogeneic blood was given to 23% of patients in group C and 18% in group R (p = 0.63). Aspirin was associated with an increase in early chest tube drainage.

CONCLUSIONS

In this surgical and perfusion environment, the authors were unable to show an advantage, from the hematologic point of view, in the routine use of a centrifugal pump head in elective coronary artery surgical patients. The use of antifibrinolytic agents and mild hypothermia may have effects on hemostasis that overshadow the influence of pump head design in this type of surgery.

Changes in hepatitis C-related liver disease in a large clinic population

BACKGROUND

Hepatitis C virus (HCV) infection is a significant problem in the Australian community. Over the past few years, the number of patients with diagnosed hepatitis C has increased greatly. The aims of the present study were to define the clinical features of a large group of patients with chronic HCV infection and to examine changes occurring in the referral base and epidemiological characteristics of this group since analysis of the first 342 patients in 1994.

METHODS

The study included 1,546 consecutive anti-HCV-positive patients who had been referred to St Vincent's Hospital from January 1990 to June 1998. Clinical and laboratory data were collected on all patients.

RESULTS

Referrals from general practitioners increased from 31% to 70% of all patients between 1990-1993 and 1994-1998. A history of injecting drug use (IDU) was present in 64% of the patients. While 89% of the IDU group was Australasian born, 49% of those in the sporadic group were born overseas. Cirrhosis was found in 18% of biopsied patients. Age, infection duration, age at infection, Mediterranean or Asian origin and a history of transfusion or lack of HCV risk factors were associated with cirrhosis on univariate analysis. Patient age was the only independent predictor of cirrhosis.

CONCLUSION

The majority of patients with HCV are diagnosed in general practice. A risk factor for infection is identified in 82% of patients. While our reported prevalence of cirrhosis may be an overestimate of that in the overall HCV community, the ultimate disease burden is likely to be significant.

Origin of constant loss in ionic conductors

We have analyzed the constant loss contribution to the ac conductivity in the frequency range 10 Hz-1 MHz and temperatures down to 8 K, for two Li ionic conductors, one crystalline (Li(0.18)La(0.61)TiO(3)) and the other glassy (61SiO(2);35Li(2)O.3Al(2)O3.P(2)O(5)). As temperature is increased a crossover is observed from a nearly constant loss to a fractional power law frequency dependence of the ac conductivity. At any fixed frequency omega, this crossover occurs at a temperature T such that omega approximately nu(0)exp(-E(m)/k(B)T), where nu(0) is the attempt frequency and E(m) is identified with the barrier for Li+ ions to leave their wells.

Nocturnal paroxysmal dystonia related to a prerolandic dysplasia

Nocturnal paroxysmal dystonia (NPD) is a rare disorder characterized by attacks of short-lived dystonic, tonic and choreoatetoid movements occurring mainly during sleep. Although seizures are believed to arise from the frontal lobe, their localization is, however, uncertain due to the lack of ictal clinical-EEG correlations. Two patients are reported with episodes clinically compatible with NPD who also experienced occasional generalized tonic-clonic seizures in which there was a frontal (prerolandic) dysplasia detected by MRI. In one patient interictal/ictal SPECTs suggested that the seizure focus was over the area of dysplasia. Both patients support the notion that NPD is a type of epilepsy arising from the frontal lobe, possibly originating in the prerolandic region.

Selective excitation of vibrational states by shaping of light-induced potentials

In this Letter we describe a method for population transfer using intense, ultrafast laser pulses. The selectivity is accomplished by careful shaping of light-induced potentials (LIPs). Creation and control of the LIPs is accomplished by choosing pairs of pulses with proper frequency detunings and time delays. As an example, selective population transfer is demonstrated for a three-state model of the sodium dimer.

Continuous positive air pressure eliminates nocturnal stridor in multiple system atrophy. Barcelona Multiple System Atrophy Study Group

We prospectively studied the sleep patterns and laryngeal function of 20 patients with multiple system atrophy and found sleep disturbances in all subjects and vocal cord abduction dysfunction in 14 (70%). In three patients with nocturnal stridor and complete vocal cord abductor dysfunction, continuous positive airways pressure eliminated laryngeal stridor, obstructive apnoea, and haemoglobin desaturation.

No evidence of linkage to 6p markers in spanish families with juvenile myoclonic epilepsy

Juvenile myoclonic epilepsy (JME) is a common subtype of hereditary generalized epilepsy with an uncertain pattern of inheritance. Different studies in multiple families have provided evidence for and against linkage of the disease to chromosome 6p. We performed linkage analysis using microsatellite markers from 6p (D6S109, D6S248, D6S291, D6S426, D6S272, D6S466, D6S294, D6S257) and from centromeric 6q region (D6S402) in seven small families of Spanish origin. The highest LOD scores were obtained under an autosomal dominant inheritance model with a penetrance of 70% but a significant positive LOD score (Z>3) was not reached. LOD scores<-2 were obtained at different markers in three of our families. These results support the concept of genetic heterogeneity in the disease.

An investigation of the early effects of manual lung hyperinflation in critically ill patients

This prospective within-group multicentre study was designed to assess the safety and short-term effectiveness of manual lung hyperinflation in mechanically ventilated patients. Eighteen patients from the intensive care units of two tertiary institutions were included and acted as their own control. Manual lung hyperinflation treatment involved patient positioning (side-lying), suctioning and manual lung hyperinflation. Side-lying treatment involved patient positioning and suctioning alone. Patients received both treatments on the day of data collection. Results demonstrated significant improvement for static respiratory system compliance (P = 0.001) with manual lung hyperinflation treatment compared to side-lying treatment. Manual lung hyperinflation treatment also cleared a significantly greater wet weight of sputum (P = 0.039). There were no differences between manual lung hyperinflation and side-lying treatment for gas exchange (PaO2/FIO2 and PaCO2), mean arterial pressure or heart rate. In conclusion, total static respiratory system compliance and sputum clearance were improved by the addition of manual hyperinflation to a physiotherapy treatment of positioning and suctioning in mechanically ventilated patients without compromise to cardiovascular stability or gas exchange.

Unilateral thalamic stroke does not decrease ipsilateral sleep spindles

STUDY OBJECTIVES

To measure the sleep spindle characteristics in patients with unilateral thalamic stroke.

DESIGN

A prospective study of patients with thalamic stroke and age-matched healthy controls.

SETTING

Department of Neurology of a University Hospital.

PARTICIPANTS

Thirteen patients (mean age: 67 years, SD: 13,44) with an isolated, unilateral acute thalamic stroke and 18 healthy age-matched volunteers.

INTERVENTIONS

A polysomnogram recording from 14 scalp EEG electrodes performed during 2 consecutive nights, the second or third week after the stroke. Only the sleep of the second night was analyzed.

MEASUREMENTS AND RESULTS

Sleep spindles were counted during two separate 10-minute epochs of stage II. Spindles appearing synchronously in both sides with similar amplitude were called "bilateral." Spindles with twice the amplitude in one side than the other were "right" or "left-side predominant". There were 8 patients with posterolateral, 3 with global and 2 with anterior lesions. Eight were right and 5 left-sided. The number of spindles was similar in patients (39.8 +/- 23.4 in 20 minutes) than controls (26.07 +/- 29.07; p=0.173). Spindles with a centroparietal (34%) and centroparieto-occipital localization (22%) were the most frequent. In controls approximately 66% of the spindles had a bilateral and symmetric distribution over the scalp, 23% of the spindles were predominantly left-sided and 5% were predominantly right-sided. In patients, bilateral spindles decreased (p<0.0001) but asymmetric spindles did not change.

CONCLUSION

Unilateral acute thalamic stroke does not decrease sleep spindles ipsilaterally; rather, it seems to produce a bilateral diminution in their number.

Hyperkalemic periodic paralysis associated with multiple sleep onset REM periods

A 24-year-old man with sporadic hyperkalemic periodic paralysis (HPP) presented with moderate excessive daytime sleepiness and transitory episodes of weakness which occurred during and after sleep. Multiple sleep latency test (MSLT) demonstrated the presence of five sleep onset REM periods (SOREMPs) and a sleep latency of five minutes. Treatment with a diuretic which decreases serum potassium resolved all the clinical symtomps and a new MSLT showed the absence of SOREMPs and a sleep latency of 13.5 minutes. To our knowledge, the patient herein reported is the first case that associates sleep abnormalities and multiple SOREMPs with HPP. Furthermore, the present case suggests that SOREMPs may be explained by an increased extracellular potassium conductance related to HPP.

[The treatment of epilepsy. A therapeutic guide of the Catalan Society of Neurology]

INTRODUCTION

There have been major advances in the treatment of epilepsy over the past ten years, leading to marked changes in the way this illness is treated. However, the introduction of new drugs and new non-drug treatments have led to uncertainty in the medical profession with regard to their exact indications. For this reason, a group of neurologists of the Catalan Society of Neurology have drawn up guide-lines for the treatment of epilepsy.

DEVELOPMENT

A panel of eight neurologists with a special interest in the diagnosis and treatment of epilepsy reviewed the literature to assess the data available regarding the treatment of epilepsy. A joint document was drawn up describing the basic rules for the use of antiepileptic drugs and the indications for other non-drug treatments.

CONCLUSION

This document is an approved therapeutic guide to the treatment of epilepsy.

Immunohistochemical localization of neurotrophins and neurotrophin receptors in human and mouse salivary glands

This study was undertaken to analyze the occurrence of low- (p75) and high-affinity (TrkA, TrkB and TrkC) neurotrophin receptor proteins in human and mouse salivary glands using immunohistochemistry. Furthermore, the presence of neurotrophins was also investigated. The study was carried out on 14 human (4 parotid, 6 submandibular and 4 sublingual glands) and 5 mouse salivary glands, using polyclonal antibodies against Trk proteins. The intensity of immunostaining was calculated automatically and evaluated in arbitrary units of grey levels. In human tissues no immunoreactivity (IR) for the assessed antigens was observed in the serous or mucous acinar cells, although TrkA IR was found in the acini of the submandibular gland. The cells of the intercalated ducts showed p75 IR (sublingual) and TrkA IR (parotid gland). The striated and excretory ducts displayed p75 IR, TrkA IR and TrkC IR in all glands, but TrkB IR was never detected. No neurotrophins were detected. In the mouse glands the ductal cells display IR for p75 (submandibular) and Trks A and C (parotid and submandibular) but not the sublingual gland. Acinar cells of the submandibular gland also show p75 IR. The only neurotrophin found in the mouse salivary glands was NGF (submandibular gland). These results suggest that neurotrophins may be involved in controlling the physiology of epithelial salivary cells.

Radiologic variables of clinical significance in the extraction of impacted mandibular third molars

OBJECTIVE

To determine which radiologic variables have a clinical significance in the extraction of impacted mandibular third molars.

STUDY DESIGN

A prospective study was carried out on 100 consecutive extractions of unilateral impacted mandibular third molars (60 women and 40 men, mean age: 26.27 +/- 10.63 years). Fourteen radiologic variables were ordinally evaluated, establishing their relation to the surgical intervention time. The Kruskal-Wallis test, a multivariant analysis of the principal components, the Pearson correlation coefficient, and logistical regression tests were carried out.

RESULTS

Seven variables (occlusal plane, relation to the second molar, depth, follicle, periodontal ligament width, ramus of the mandible, and angulation) demonstrated a statistically significant relation to the surgical intervention time (Kruskal-Wallis tests, p < 0.007). Two associated variables, depth and periodontal ligament width, showed the most powerful and simple relation to the surgical intervention time (r2 multiple = 0.307, p < 0.001).

CONCLUSION

The model we propose is a tool that may help the general practitioner to establish competence in an extraction of the impacted mandibular third molar by measuring the association of two radiologic variables: depth and periodontal ligament width.

What is the relationship between arachnoid cysts and seizure foci?

PURPOSE

Arachnoid cysts are sometimes encountered in MRIs performed for a variety of reasons. In patients with epilepsy, particularly those with refractory epilepsy, arachnoid cysts are often assumed to be related to their seizure focus. We conducted a study to investigate this putative relationship.

METHODS

A retrospective study on the incidence of arachnoid cysts was performed in patients seen in our Epilepsy Clinic who had CT or MRI scans, interictal EEGs or ictal EEGS. Locations of seizure foci in these patients were defined from clinical and electrophysiologic data.

RESULTS

Seventeen of 867 patients had arachnoid cysts. Twelve patients had temporal lobe cysts and only 3 of them had temporal lobe seizures. Four patients had frontal lobe cysts and only 1 had frontal lobe seizures ipsilateral to the cyst. One patient had a cerebello-pontine angle cyst and frontal lobe seizures. Thus, clinical manifestations of seizures and EEG findings (interictal and/or ictal) indicated that the seizure focus was adjacent to the cysts in only 4 patients (23.5%).

CONCLUSIONS

Our findings suggest that arachnoid cysts are often an incidental finding in patients with epilepsy and do not necessarily reflect the location of the seizure focus.

Mercury distribution and renal metallothionein induction after subchronic oral exposure in rats

The effects of long-term daily intake of low and high levels of mercury on its organ distribution and binding to renal metallothionein (MT) in male rats were studied. The animals were exposed to mercuric chloride labelled with 203Hg via drinking water for 8 weeks (5, 50 and 500 microM Hg). The greatest concentration of mercury was found in the kidneys. Similar levels of radioactivity in the buccal cavity and oesophagus were also observed by whole-body autoradiography. In the kidneys, the mercury was accumulated in the outer stripe of the outer zone of the medulla and, to a minor degree, in the renal cortex. Almost 50% the total renal mercury was associated to MT. The binding capacity of the renal MT for mercury tends to saturate with increasing doses, thus this means that the capacity of the kidneys to accumulate mercury is limited.

Incision Depth vs. Incision Number in the Rupture Strength of Pig Eyes Following Radial Keratotomy

The effects of incision depth and the number of incisions on globe rupture were studied in porcine enucleated eye model. In one group, radial keratotomy was performed using a diamond blade set at 100%, 75%, and 50% of corneal thickness. In another set of eyes, 16, 8, and 4 incisions were made with the diamond knife set at 100% of corneal thickness. The eyes were then subjected to blunt trauma. The mean energy of globe rupture for incisions at 100%, 75%, and 50% of corneal thickness was 3.0, 4.2, and 4.6 joules respectively. In contrast, mean energy of globe rupture for 16, 8, and 4 incisions at 100% corneal thickness was 2.8, 2.9, and 3.0 joules, respectively. This study suggests that incision depth in radial keratotomy reduces the strength of the cornea more than incision number.

Cyclosporine-associated mutism in liver transplant patients

Four liver transplant recipients treated with cyclosporine developed a reversible neurologic syndrome characterized by a speech disorder leading to mutism. This complication, previously reported in a few liver transplant recipients treated with the immunosuppressive drug FK506, had not been described with cyclosporine. Recognition of this syndrome should prompt withdrawal of the drug and avoidance of unnecessary diagnostic procedures.

Whole-body retention, and urinary and fecal excretion of mercury after subchronic oral exposure to mercuric chloride in rats

The effects of long-term daily intake of mercury on its urinary and fecal excretion, whole-body retention, and blood concentration in male rats were observed. The animals were exposed to mercuric, chloride labeled with 203Hg via drinking water for 8 weeks (5, 50 and 500 microM Hg). 203Hg in urine, feces and blood was quantified. The blood mercury concentration did not keep a linear relationship with the increasing dose. The percentage of the total amount of mercury intake which is excreted by the fecal route in rats exposed to 500 microM Hg was significantly lower than in those exposed to 5 and 50 microM. The daily dose percentage of mercury excreted in urine increased with dose size. The results show that the absorption fraction of mercury through the gastrointestinal tract (30-40%) was higher than values previously reported.

Effects of long-term antiepileptic therapy on the catabolism of testosterone

The serum levels of testosterone, sex hormone binding globulin, and free testosterone index were measured in 51 epileptic men (age 18-45) in order to assess the possible effects of antiepileptic drugs on sexual dysfunction. An analytical gas chromatography-mass spectrometry method was developed to assess the urinary excretion of testosterone, epitestosterone, androsterone, etiocholanolone, 11-OH androsterone and 11-OH etiocholanolone and to evaluate if the catabolism of testosterone had been increased. Twenty normal healthy males of similar age, 18-45 years, served as control group. Patients receiving polytherapy (n = 34) or monotherapy with carbamazepine (n = 8) or phenytoin (n = 9) showed higher levels of sex hormone binding globulin and testosterone, and lower levels of free testosterone than did the controls (P < 0.03). Urinary excretion of the metabolites androsterone and 11-OH androsterone was significantly reduced (P < 0.02) in the polytherapy group, while the monotherapy group showed only significant differences (P < 0.02) in the elimination of 11-OH androsterone. Our results suggest that an induction of the hepatic synthesis of sex hormone binding globulin may be the mechanism by which the antiepileptic drugs lower the levels of free testosterone in serum. However, the reduced excretion of androsterone and the normal levels of etiocholanolone show that the antiepileptic drugs do not produce an increase in the main catabolism pathway of testosterone.

The low risk cardiac patient: an opportunity for cost containment

The pressure to maintain high standards in the face of diminished medical funding has promoted a search for a low risk group of patients seen in cardiac practice in whom diagnostic and therapeutic technologies can be kept to a minimum. This study reports experience in a single cardiology practice in which all patients had a history taken, a clinical examination performed, and most had an electrocardiogram. Thereafter investigation and treatment was tailored to the individual patient's need. A retrospective study of 113 patients revealed that 93 (82%) had high risk characteristics prior to their death: cardiac failure; unstable coronary heart disease; clinical or laboratory evidence of poor systolic function of the left ventricle or inoperable coronary artery disease; elective major surgery; evidence of poor prognosis due to non-cardiac disease. In contrast, only 124 (21%) of 588 consecutive patients seen in consultation had high risk characteristics. The prevalence adjusted mortality ratio of high to low risk cases was 17.4/1 and in one third of cases, high risk status was less than 6 months duration. In a prospective study, 144 cases were classified at high risk and 373 at low risk. Three year survival rates were 74 and 91% respectively (p < 0.0001). 46 (12.3%) of the 373 patients initially at low risk subsequently developed clinical features which permanently placed them in the high risk category. The 3 year survival in the low to high risk converters was 47% compared with 97% survival in those remaining at low risk throughout the period of observation (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Pediatric analgesia and sedation

Sedation and analgesia are essential components of the ED management of pediatric patients. Used appropriately, there are a number of medications and techniques that can be used safely in the emergency care of infants and children. Emergency physicians should be competent in the use of multiple sedatives and analgesics. Adequate equipment and monitoring, staff training, discharge instructions and continuous quality management should be an integral part of the ED use of these agents.

Blood transfusion has no effect on colorectal cancer survival. A population-based study

This study was conducted to evaluate the impact on survival of perioperative blood transfusion in a series of 698 colorectal cancer patients undergoing radical surgery. Patients were identified, and follow-up was carried out by the local population-based cancer registry. Data on blood transfusion was obtained by record linkage with the files of the blood banks operating in the area covered by the registry. Prognostic factors were age, Dukes stage and topography of the primary tumour. Relative risk (RR) for Dukes B patients was 1.53 [95% confidence interval (CI) 0.94-2.50] and for Dukes C, 3.57 (95% CI 2.22-5.75) when compared with Dukes A patients. For the left colon, RR was 0.96 (0.61-1.52) and for the rectum 1.87 (1.22-2.86) when compared with the right colon. When adjusting for these factors and excluding operative mortality, RR for transfused patients was 1.16 (95% CI 0.87-1.55). It is concluded that blood transfusion does not adversely affect survival in colorectal cancer patients.

Association of C4B deficiency (C4B*Q0) with erythema nodosum in leprosy

A considerable number of studies have postulated significant associations between susceptibility to the different clinical manifestations of leprosy and the MHC. In this investigation, the association between the MHC class III complement proteins C2, BF, C4A and C4B and leprosy in a patient population of Southern Brazil was studied. A total of 109 non-related leprosy patients was investigated; 73 presented with lepromatous leprosy (LL), 46 of them had the immunopathological reaction of erythema nodosum (ENL), the remaining 36 were tuberculoid, borderline and indeterminate leprosy (TIBL) patients. The control group included 172 healthy individuals matched with the patients according to their ethnic and geographical origin. C2, BF, C4A and C4B allotypes were determined by standard technologies including Western blots for C2 and C4 variant alleles with monoclonal and polyclonal antibodies. Non-expressed ('silent') C4 alleles in hemizygously deficient individuals were estimated semiquantitatively on the basis of the C4A and C4B isotype ratio and by the MASC ('minimal chi-square') method. The results showed a significantly elevated presence of the non-expressed C4B allele (C4B*Q0) in the LL and ENL patient groups in comparison with the controls. The most significant difference was observed in the ENL group when compared with the controls. In addition, all patients who were homozygously C4B-deficient had ENL, and most of them had the BF*F1 allele. The comparison between LL patients with and without ENL also showed a statistically significant difference in the presence of C4B*Q0, indicating that C4B deficiency itself is associated with ENL. The relative risk of LL patients with the C4B*Q0 allele suffering from ENL was 5.3 compared with LL patients without C4B*Q0. Since immune complexes (IC) are considered to be the pathogenic cause of ENL, our findings indicate that C4B deficiency may play an important role in the abnormal immune response against Mycobacterium leprae and in the lack of IC clearance, leading to ENL reactions. Individuals with this allele seem to be at a higher risk of developing pathological immune reactivity in lepromatous leprosy.