Genotypic testing on HIV-1 DNA as a tool to assess HIV-1 co-receptor usage in clinical practice: results from the DIVA study group.

PURPOSE: We have developed a sequencing assay for determining the usage of the genotypic HIV-1 co-receptor using peripheral blood mononuclear cell (PBMC) DNA in virologically suppressed HIV-1 infected patients. Our specific aims were to (1) evaluate the efficiency of V3 sequences in B versus non-B subtypes, (2) compare the efficiency of V3 sequences and tropism prediction using whole blood and PBMCs for DNA extraction, (3) compare the efficiency of V3 sequences and tropism prediction using a single versus a triplicate round of amplification. RESULTS: The overall rate of successful V3 sequences ranged from 100 % in samples with >3,000 copies HIV-1 DNA/10(6) PBMCs to 60 % in samples with <100 copies total HIV-1 DNA /10(6) PBMCs. Analysis of 143 paired PBMCs and whole-blood samples showed successful V3 sequences rates of 77.6 % for PBMCs and 83.9 % for whole blood. These rates are in agreement with the tropism prediction obtained using the geno2pheno co-receptor algorithm, namely, 92.1 % with a false-positive rate (FPR) of 10 or 20 % and of 96.5 % with an FPR of 5.75 %. The agreement between tropism prediction values using single versus triplicate amplification was 98.2 % (56/57) of patients using an FPR of 20 % and 92.9 % (53/57) using an FPR of 10 or 5.75 %. For 63.0 % (36/57) of patients, the FPR obtained via the single amplification procedure was superimposable to all three FPRs obtained by triplicate amplification. CONCLUSIONS: Our results show the feasibility and consistency of genotypic testing on HIV-1 DNA tropism, supporting its possible use for selecting patients with suppressed plasma HIV-1 RNA as candidates for CCR5-antagonist treatment. The high agreement between tropism prediction by single and triple amplification does not support the use of triplicate amplification in clinical practice.

Syphilis with HIV in Florence, 2003-2009: a 7-year epidemiological study.

The aims of this study were to describe the trend of acquired syphilis in the city of Florence and its province over a 7-year period, to investigate sexual behaviours in the syphilis-infected population and to analyse syphilis/HIV co-infection. A total of 259 patients were classified according to age, sex and HIV infection. We estimated that from 2004 to 2008 cases increased by 248%. Most patients with concurrent HIV infection were male (31-45 years), but 40- to 60-year-old men who had sex with men predominated in both male and HIV-positive patients. Oral sex was identified as the most significant route of transmission, although most patients did not consider it so. Late-presenters with HIV accounted for 33% of HIV-positive patients: they were unaware of their HIV status and showed syphilis lesions only. In these cases, syphilis heralded the presence of HIV infection and allowed earlier diagnosis.

Bacterial skin and soft tissue infections: review of the epidemiology, microbiology, aetiopathogenesis and treatment: a collaboration between dermatologists and infectivologists.

Bacterial skin and soft tissues infections (SSTI) often determine acute disease and frequent emergency recovering, and they are one of the most common causes of infection among groups of different ages. Given the variable presentation of SSTI, a thorough assessment of their incidence and prevalence is difficult. The presence of patient-related (local or systemic) or environmental risk factors, along with the emergence of multi-drug resistant pathogens, can promote SSTI. These infections may present with a wide spectrum of clinical features and different severity, and can be classified according to various criteria. Many bacterial species can cause SSTI, but Gram-positive bacteria are the most frequently isolated, with a predominance of Staphylococcus aureus and Streptococcus pyogenes. The diagnosis of SSTI requires an extended clinical history, a thorough physical examination and a high index of suspicion. Early diagnosis is particularly important in complicated infections, which often require laboratory studies, diagnostic imaging and surgical exploration. SSTI management should conform to the epidemiology, the aetiology, the severity and the depth of the infection. Topical, oral or systemic antimicrobial therapy and drainage or debridement could be necessary, along with treatment of a significant underlying disease. This review discusses the epidemiology, the pathogenesis and the classification of bacterial SSTI, describes their associated risk factors and their clinical presentations. The authors provide a rational diagnostic and therapeutic approach to SSTI in respect of antibiotic resistance and currently available antimicrobial agents.

Use of patch testing for the diagnosis of abacavir-related hypersensitivity reaction in HIV patients.

BACKGROUND: The use of antiretroviral drug abacavir (ABC) has been often associated with cutaneous hypersensitivity reactions, the majority being severe. OBJECTIVE: The present study discusses the issues of patch testing associated with pharmacogenetic screening in light of the development of abacavir hypersensitivity reactions (HSRs). METHODS: The present authors classified 100 patients into three groups: 20 patients (group A) had experienced a hypersensitivity reaction when treated with highly active antiretroviral therapy (HAART) including ABC; 60 HIV-positive patients (group B) were receiving HAART scheme including ABC; 20 HIV-negative patients acted as control group (group C). Patients of group A and B were patch tested with ABC as such, then with an ABC extract diluted to 1 and 10% in petrolatum. Group C patients underwent patches with petrolatum only. A biopsy of the lesion was performed in those patients who showed a positive skin reaction. All patients had been tested for HLA-B5701. RESULTS: A correlation between positive ABC-patch testing and HLA-B5701 was found in 50% of patients enrolled in group A, while in group B and C, all patients tested negative for both genetic marker and ABC-patch testing. Histopathology findings confirmed a vigorous CD4+ and CD8+ cellular response that is compatible with HSR. CONCLUSIONS: Patch testing is a safe and sensitive method that can be used for to confirm or exclude any correlation between abacavir and hypersensitivity skin reactions in patients who have been previously treated with abacavir during HAART. Correlation between patch test, immunohistochimical, and genetic tests results shows that genetic testing increases the possibility to identify patients with a true reaction.

Italian guidelines for the diagnosis and infectious disease management of osteomyelitis and prosthetic joint infections in adults.

Bone and joint infections are recognized as difficult-to-treat infections that result in significant morbidity and mortality among patients and increased healthcare costs. This article presents the recommendations for the diagnosis and management of osteomyelitis and prosthetic joint infections in adults developed by Bone and Joint Infections Committee for the Italian Society of Infectious and Tropical Diseases. It contains data published through to November 2007. An evidence-based scoring system that is used by the Infectious Diseases Society of America was applied to treatment recommendations.

Disseminated Scedosporium apiospermum infection in renal transplant recipient: long-term successful treatment with voriconazole: a case report.

Scedosporium apiospermum, the asexual form of Pseudallescheria boydii, is a ubiquitous fungus that represents an unfrequent complication of immune suppression. It accounts for 20% of all non-Aspergillus mold infections in organ transplant recipients. The infection can be localized or disseminated in multiple organs, including lungs, brain, joints, tendons, and skin, and is difficult to treat, due to resistance of S apiospermum to amphotericin B and other antifungal agents. The mortality rate is about 50%. To our knowledge, there are no prospective studies or registries of transplant recipients to guide diagnosis and there are no evidence-based recommendations for the optimal management of this infection. We report a case of S apiospermum infection in a woman with renal transplantation. The first occurrence of infection was a solitary nodule on the forearm, which was surgically excised. Two following relapses were disseminated to the knee, the Achilles tendon, and the skin of the left leg. The infection was successfully treated with voriconazole, but due to the severe iatrogenic immune suppression, a strong reduction in immunosuppressant drugs was needed.

[Bacterial meningitis in adults: a retrospective multicentric study in Tuscany (Italy)]. / Le meningiti batteriche dell'adulto: studio retrospettivo multicentrico della Toscana.

The Infectious Diseases Unit of Lucca Hospital conducted a multicentric retrospective study to evaluate the epidemiological and clinical features of adult patients affected by bacterial meningitis attending all the Infectious Diseases Units of Tuscany (Italy) from July 1999 to June 2004. A specific questionnaire was sent to all the units to collect information about each case of bacterial meningitis occurring in patients older than sixteen. Patients with meningitis by Mycobacterium tuberculosis were excluded from the analysis. Nine out of 12 Infectious Diseases Units of Tuscany took part in the study and 197 cases were identified. Most cases of meningitis occurred during 2002 with a slight reduction in cases in subsequent years. Streptococcus pneumoniae and Neisseria meningitidis were the most frequently isolated pathogens with an increase in diagnosis from 1999 to 2004; in 23.8% of patients no pathogens were isolated, with a reduction in meningitis from unknown aetiology from 1999 to 2004. Most patients were treated with a combination of two antibiotics, and corticosteroid drugs were added to the therapy; in the group of patients treated with corticosteroid drugs invalidating complications occurred in 23% of cases and 5% of patients died. In all, 27 out of 197 subjects (13.7%) developed invalidating complications and 20 out of 197 patients (10.2%) died.

Amplification of 18 dystrophin gene exons in DMD/BMD patients: simultaneous resolution by capillary electrophoresis in sieving liquid polymers.

Duchenne (DMD) and Becker (BMD) muscular dystrophies are the two most common myopathies described so far. In the late 80s, Chamberlain et al. and Beggs et al. proposed two PCR assays allowing detection of over 98% DMD/BMD deletions. Since each of them is based on specific co-amplification of 9 dystrophin gene exons, a method attempting simultaneous analysis of DMD/BMD should offer unambiguous resolution and identification of 18 DNA fragments ranging in size from approximately 100 to 500 bp. We have developed a novel capillary electrophoresis method that allows simultaneous analysis of the two PCR sets with full diagnostic value. It consists of (a) an ultrastable inner capillary coating based on a novel acrylamide monomer (N-acryloyl amino ethoxy ethanol); (b) a very low viscosity (barely 70 mPa) sieving polymer solution, formed by short-chain (average mol wt of 230,000, 55,000 Mn) polyacrylamides; (c) substitution of four fragments in the classical multiplex reaction (181 and 535 bp in the Beggs, 416 and 459 bp in the Chamberlain) with four new fragments of different lengths (170, 313, 154 and 88 bp, respectively). These new conditions allow resolution and unambiguous identification of all 18 PCR-amplified fragments in a single electrophoretic run. The set of 18 fragments comprises the following: 88, 113, 139, 154, 170, 196, 202, 238, 268, 271, 313, 331, 357, 360, 388, 410, 506 and 547 bp.

Chronic cryptosporidiosis in patients with AIDS: stable remission and possible eradication after long-term, low dose azithromycin.

AIMS: To investigate the effectiveness of long term, low dose azithromycin treatment for chronic cryptosporidiosis in patients with AIDS. METHODS: Azithromycin was administered as initial daily treatment to 13 patients with AIDS: 6 patients received 500 mg for 30 to 40 days (mean 35); 3 patients received 1000 mg for 21 to 50 days (mean 37); and 4 patients received 1500 mg for 20 days. Nine of the 13 patients were also given low dose maintenance treatment with different schedules of azithromycin for 30 to 360 days (mean 129). Patients were monitored, during and after treatment, for parasite shedding in stool and for daily stool frequency and body weight. All but one patient had severe immunodeficiency. RESULTS: Long term, low dose maintenance treatment was associated with major clinical and parasitological benefits: there was probable eradication of infection in 2 patients, and 7 patients showed a complete response with persistent high decrease (5 patients) or clearance (2 patients) of parasite in stool. The drug was well tolerated, and there was no relapse either during treatment or during follow up (up to 21 months). These results were more impressive than those observed after the short term initial course of azithromycin, which was unable at any tested dose to achieve parasite clearance in stool (except in the patient with less advanced immunodeficiency) or to prevent relapse in 3 patients who discontinued treatment. Reversible side effects occurred with the 1500 mg daily dose. CONCLUSIONS: Long term, low dose azithromycin is well tolerated and may induce stable remission of chronic cryptosporidiosis in patients with AIDS. It may lead to probable eradication of the infection in some patients, even those with severe immunodeficiency.

Enterocytozoon bieneusi in AIDS: symptomatic relief and parasite changes after furazolidone.

AIMS: To investigate changes in morphology of the developmental stages of Enterocytozoon bieneusi and symptomatic relief observed in AIDS patients after treatment with furazolidone. METHODS: Six AIDS patients with symptomatic E bieneusi infection of the small intestine were treated with a course of furazolidone. All patients had a weekly monitoring of parasite shedding in stool by light microscopy during and after treatment. At the end of the treatment, duodenal biopsy specimens obtained from three patients were studied by transmission electron microscopy by two pathologists who were unaware of the patients' treatment. RESULTS: All patients showed both clinical and parasitological response with transient clearance or decrease of spore shedding in stool. After treatment, alterations in faecal spores were observed in all patients by light microscopy, and ultrastructural changes in E bieneusi at all stages of the life cycle were demonstrated in biopsy specimens of the three patients who underwent post-treatment endoscopy. CONCLUSIONS: The clinical benefit seen after treatment with furazolidone in six AIDS patients with E bieneusi intestinal infection may be due to damage to the developmental stages causing a partial inhibition to reproduction of the parasite.

Persistent damage to Enterocytozoon bieneusi, with persistent symptomatic relief, after combined furazolidone and albendazole in AIDS patients.

AIM: To investigate morphological changes in Enterocytozoon bieneusi and the duration of symptomatic relief after combination treatment with furazolidone and albendazole in AIDS patients. METHODS: Four severely immunocompromised AIDS patients with symptomatic E bieneusi infection of the gut received an 18 day course of combined furazolidone and albendazole (500 + 800 mg daily). All patients were monitored for parasite shedding in stool by light microscopy at the end of treatment and monthly during follow up. At the end of treatment, duodenal biopsy specimens obtained from three patients were studied by transmission electron microscopy by two pathologists blind to the patients' treatment or clinical outcome. Duodenal biopsy specimens obtained from one of the patients two months after completion of treatment were also studied electronmicroscopically. RESULTS: All patients had long lasting symptomatic relief, with a major decrease--or transient absence--of spore shedding in stools from completion of treatment. After treatment, changes in faecal spores were persistently found by light microscopy in all cases, and there was evidence of both a substantial decrease in the parasite load and ultrastructural damage in the parasite in all biopsy specimens. The treatment was well tolerated, and no patient had clinical or parasitological relapse during follow up (up to 15 months). CONCLUSIONS: The long lasting symptomatic relief observed in all four treated patients correlated with the persistent decrease in parasite load both in tissue and in stool, and with the morphological changes observed in the life cycle of the protozoan. These data suggest that combined treatment with furazolidone and albendazole is active against E bieneusi and may result in lasting remission even in severely immunocompromised patients.

Strongyloides stercoralis: ultrastructural study of newly hatched larvae within human duodenal mucosa.

AIM: To investigate the ultrastructural features of the newly hatched larvae of Strongyloides stercoralis in human duodenal mucosa. METHODS: Duodenal biopsies from an AIDS patient were studied by transmission electron microscopy to investigate morphology, location, and host-worm relations of newly hatched larvae. RESULTS: Newly hatched larvae were found in the Lieberkuhn crypts within the tunnels formed by migration of parthenogenic females. Delimiting enterocytes were compressed. Release of larvae into the gut lumen was also documented. It was shown that both a thin and a thick membrane surrounded the eggs and larvae, as a tegument derived respectively from parasite and host. Segmentary spike-like waves, caused by contractures of worm body musculature, were observed on the surface of newly hatched larvae, and their intestinal lumen was closed and empty, with no budding microvilli. Immaturity of the cuticle and some degree immaturity of amphidial neurones were found, but there was no evidence of either immaturity or signs of damage to other structures. CONCLUSIONS: Newly hatched larvae of S stercoralis appear to be a non-feeding immature stage capable of active movement through the epithelium, causing mechanical damage. The tegument resulting from the thin and the thick membrane may protect the parasite and reduce any disadvantage caused by immaturity.

Central nervous system involvement during infection by Phlebovirus toscana of residents in natural foci in central Italy (1977-1988).

Central nervous system (CNS) involvement was detected during infection caused by the sand fly-transmitted Phlebovirus Toscana. One hundred fifty-five cases of Toscana virus-associated meningitis or meningoencephalitis were identified in a survey that lasted ten years, conducted in two regions of central Italy. Diagnosis was performed by different serologic tests. A combination of hemagglutination-inhibition and plaque-reduction neutralization or indirect immunofluorescence for IgM, and enzyme-linked immunosorbent assays for IgM were considered the most suitable tests for the diagnosis of Toscana virus infection. A few strains of Toscana virus were isolated from the cerebrospinal fluid of seropositive patients. Toscana virus-associated CNS disease occurred during the summer, reaching a peak value in August, when the maximum activity of the sand fly vector occurs and virus isolates are obtained in their natural foci. The results suggest that Toscana virus should be considered as a possible cause of CNS disease in Mediterranean countries where sand flies of the genus Phlebotomus are known to be present.

Evaluation of a rapid immunochromatographic test for the serologic diagnosis of tuberculosis in Italy.

OBJECTIVE: To determine specificity, sensitivity and predictive values of a rapid immunochromatographic assay (ICT tuberculosis) for the diagnosis of tuberculosis (TB) in an Italian clinical setting, and to identify tentative new guidance for the interpretation of test results. METHODS: The ICT tuberculosis test is an immunochromatographic test based on the detection of IgG antibodies directed against five highly purified antigens secreted by Mycobacterium tuberculosis during active growth. Sera from 60 patients with active pulmonary (48 sputum smear-positive and six sputum smear-negative cases) and extrapulmonary (six cases) TB were obtained. Personal, anamnestic and clinical data were investigated and recorded for each patient. The control groups comprised 156 subjects: 40 healthy individuals, half of them Mycobacterium bovis BCG-vaccinated, and 116 patients with mycobacterial diseases other than TB (five cases), with nonmycobacterial lung diseases (30 cases), with nonmycobacterial nonlung diseases (30 cases), with nonmycobacterial diseases and rheumatoid factors positivity (30 cases), and with asymptomatic HIV infection (21 cases). For 21 individuals the test was simultaneously performed with both serum and whole blood sample. Each positive result of the ICT test was reported with regard to the number (1-4), position (A, B, C, D) and color intensity (+ to ++++) of the evidenced lines in order to assess the quality of the antibody response. RESULTS: The overall sensitivity and specificity were 56.7% and 90.4%, respectively. The sensitivity for pulmonary TB patients was 61.1% (66.7% for smear-positive and 16.7% for smear-negative cases) and 16.7% for extrapulmonary TB patients. The difference between ICT results in pulmonary TB patients and control subjects was statistically significant (P < 0.0001). The analysis of the positive ICT tests revealed that samples with strong color intensity (>/=++) and specific antibodies bound to antigens immobilized on line D were significantly more frequent in TB patients than in controls (P = 0.001 and P= 0.027, respectively). ICT test results with the presence of at least three visible lines were more often observed in the TB patients than in controls, although not reaching statistical significance (P = 0.052). No difference was observed between the results of the ICT test performed both on serum and whole blood sample. CONCLUSIONS: The ICT tuberculosis test was confirmed to be rapid and easy to perform without requiring special equipment, both on serum and whole blood sample. Our data, in accordance with those obtained in a previous study conducted in extra-European countries, confirmed higher sensitivities for the smear-positive TB patients than for the smear-negative TB patients, and for pulmonary TB patients than for the extrapulmonary TB patients. Data obtained on the quality of antibody response in the ICT positive samples, might be used to improve the performance of the test.

CAG triplet analysis in families with androgen insensitivity syndrome by capillary electrophoresis in polymer networks.

The potential use of capillary zone electrophoresis in polymer networks (linear polymers above the entanglement threshold, added to the background electrolyte for sieving purposes) for analysis of DNA fragments amplified by a polymerase chain reaction, is shown. In typical runs, the capillary is filled with Tris-borate-EDTA buffer, at pH 8.3, containing 6% linear polyacrylamide as a dynamic sieving matrix. Such formulations allow replenishing the capillary with fresh sieving solution when resolution decays after prolonged use (typically > 30 injections per capillary are obtained). The DNA fragments are detected by their intrinsic absorbance at 254 nm. This system has been applied to the analysis of CAG triplet polymorphism in families carrying the androgen insensitivity syndrome. While easy separation is obtained for fragments 139 base pairs (bp) and 160 bp (in families carrying a difference of 7 CAG repeats) even more difficult cases (such as those of families exhibiting fragments of 136 and 139 bp, thus differing by only one CAG repeat) are resolved with precision and diagnostic value.

Isolation of Borrelia burgdorferi in Tuscany (Italy).

To evaluate the diffusion of Borrelia burgdorferi in Tuscani (Italy) 720 ticks were collected and subsequently cultured for Borrelia burgdorferi. A strain of Borrelia burgdoferi was isolated from one tick; this being the first such reported identification in Central-Southern Italy.

Blood viscosity and red cell morphology in subjects suffering from cirrhosis before and after treatment with S-adenosyl-L-methionine (SAM).

Alterations of fluidity of the hepatocytic membrane and of the transport related systems are the basis of the cholesteatic syndrome and favour the tissue accumulation of cytotoxic metabolites. S-Adenosyl-L-Methionine (SAM) is a natural molecule which acts as a giver of methylic groups and as an enzymatic activator in several enzymatic actions of transmethylase and of transulphuration and plays a key role in biochemical processes of hepatic cell. The aim of our study was to evaluate the effects of SAM on the restoration of the membrane fluidity and on the hepatic function in general. In studying the fluidity of the cell membrane we evaluated some hemorheological parameters (total blood viscosity and red cell morphology). Fluidity of the red cell membrane is one of the most important elements of red cell rheology. We studied 15 patients (Group A) suffering from micro- and macro-nodular cirrhosis verified through hepatic biopsy, with alcoholic or post-viral causes. We evaluated the values of: blood viscosity (with a cone-plate rheometer by Carri-med), haematocrit, plasma fibrinogen and the erythrocytic morphology at the optical microscope with the Zipursky-Forconi method before and after 7 days of therapy with SAM i.v.. Data were compared with those of a similar group (Group B) treated with traditional therapy only (hyposodic and hypoprotein diet supplemented with multivitamin preparations, vitamin K in particular, if necessary, and potassium sparing diuretics). We also measured biliary salts, alkaline phosphatase, transaminase and gamma-GT. In the first group we observed a statistically significant reduction of blood viscosity, haematocrit didn't change significantly; biliary salts reduced in a statistically significant way. Evaluation of red cell morphology showed in all cases a pathological percentage (>15%) of echinocytes and knizocytes which reduced to a mean of 5% after SAM therapy. We observed no further modifications of the other hemorheological parameters. Results demonstrate that SAM has a positive action on the fluidity of the membrane, as indicated by the improvement of haemorheological parameters and by the significant decrease of biliary salts, indicating the presence of cholesteasis.

Evaluation of erythrocyte morphology as deformability index in patients suffering from vascular diseases, with or without diabetes mellitus: correlation with blood viscosity and intra-erythrocytic calcium.

The aim of our study was to evaluate the erythrocytic morphology in vascular patients, with or without diabetes, showing cell alterations correlated to blood viscosity and intra-erythrocytic calcium. We studied 108 subjects: 20 normal subjects, 58 vascular patients (25 suffering from CHD, 19 from CVD, 14 from POAD) and 30 non-insulin-dependent diabetes patients with vascular disease in metabolic compensation (13 CHD, 9 CVD, 8 POAD). Erythrocytic morphology, blood viscosity and intra-erythrocytic calcium were evaluated. Our results show that bowls, the most deformable red cells, decreased significantly in vascular patients and in POAD diabetics, while the discocytes, having a stiffer form, greatly increased in subjects suffering from ischemic disease and in POAD diabetics. The altered red cells (echinocytes and knizocytes) reached a statistical significance in CVD and POAD diabetics. Comparing the percentage of discocytes to intraerythrocytic calcium content in vasculopathic subjects, we obtained a significant correlation. No evidence of a relationship between discocytes and blood viscosity was found, even if blood viscosity significantly increased in patients affected by ischemic disease. These results suggest that ischemia decreases the deformability of red cells which is supported by the study of red cells morphology, by the erythrocytic morphology index (EMI), which becomes < 1, and by the evaluation of cytosolic calcium content.

Variations of erythrocyte morphology in different pathologies.

In our study we evaluated erythrocytic morphology in different pathologies which can modify flowing red cells. We followed the methodology proposed by Zipursky which allows a three-dimensional evaluation of the red cell and a classification according to the shapes observed through the optical microscope. We studied 150 subjects: 20 normal subjects, 58 patients suffering from vascular diseases, 40 affected by diabetes (type II) (10 without and 30 with vascular diseases), 22 patients with liver disease, 5 patients with monoclonal gammopathies and 5 dehydrated patients. Results show that in normal subjects bowls, which is the shape of the most deformable red cells, are more (55%) than discocytes (44%); the altered forms are only 1%. In vascular patients we noted a statistically significant increase of discocytes (60%). There are no significant differences between subjects affected by diabetes without vascular disease and normal subjects. In diabetics with vascular diseases there are more discocytes (57%) and some altered forms (3%). In patients suffering from chronic hepatitis a great increase (13%) in echinocytes and knizocytes was noticed, which suggests an alteration in the fluidity of the membrane. Our observations testify the importance of this simple methodology in focusing the morphological alterations which can be accounted for both by pathologies of the red cells and by changes in their metabolism.