Polystyrene nanoplastics as an ecotoxicological hazard: cellular and transcriptomic evidences on marine and freshwater in vitro teleost models.

The contamination of marine and freshwater environments by nanoplastics is considered a global threat for aquatic biota. Taking into account the most recent concentration range estimates reported globally and recognizing a knowledge gap in polystyrene nanoplastics (PS-NPs) ecotoxicology, the present work investigated the harmful effects of 20 nm and 80 nm PS-NPs, at increasing biological complexity, on the rainbow trout Oncorhynchus mykiss RTG-2 and gilthead seabream Sparus aurata SAF-1 cell lines. Twenty nm PS-NPs exerted a greater cytotoxicity than 80 nm ones and SAF-1 were approximately 4-fold more vulnerable to PS-NPs than RTG-2. The engagement of PS-NPs with plasma membranes was accompanied by discernible uptake patterns and morphological alterations along with a nuclear translocation already within a 30-min exposure. Cells were structurally damaged only by the 20 nm PS-NPs in a time-dependent manner as indicated by distinctive features of the execution phase of the apoptotic cell death mechanism such as cell shrinkage, plasma membrane blebbing, translocation of phosphatidylserine to the outer leaflet of the cell membrane and DNA fragmentation. At last, functional analyses unveiled marked transcriptional impairment at both sublethal and lethal doses of 20 nm PS-NPs, with the latter impacting the "Steroid biosynthesis", "TGF-beta signaling pathway", "ECM-receptor interaction", "Focal adhesion", "Regulation of actin cytoskeleton" and "Protein processing in endoplasmic reticulum" pathways. Overall, a distinct ecotoxicological hazard of PS-NPs at environmentally relevant concentrations was thoroughly characterized on two piscine cell lines. The effects were demonstrated to depend on size, exposure time and model, emphasizing the need for a comparative evaluation of endpoints between freshwater and marine ecosystems.

Estudio prospectivo, aleatorizado comparativo entre el bloqueo guiado por ultrasonidos de las ramas cutáneas laterales de los nervios intercostales frente a analgesia convencional en cirugía no reconstructiva de mama / Prospective, randomized comparative study of ultrasound-guided blocking of the lateral cutaneous branches of the intercostal nerves versus conventional analgesia in non-reconstructive breast surgery

Objetivo: Nuestro objetivo es evaluar si la realización de un bloqueo interfascial, el bloqueo de las ramas cutáneas de los nervios intercostales en la línea axilar media (BRILMA) asociado a una pauta analgésica multimodal mejora la analgesia postoperatoria y permite ahorrar opioides tras cirugía no reconstructiva de mama. Material y métodos: Realizamos un estudio aleatorizado y prospectivo simple, donde los pacientes fueron sometidos a cirugía no reconstructiva de mama. Los pacientes fueron asignados aleatoriamente al grupo de realización del bloqueo, o al grupo de analgesia postoperatoria estándar (paracetamol y dexketoprofeno). Las variables principales analizadas fueron la intensidad del dolor evaluada mediante la escala numérica verbal y las necesidades de rescate analgésico con tramadol. Resultados: Se observaron diferencias estadísticamente significativas en el consumo de tramadol durante el periodo de estudio (10,5mg en el grupo BRILMA, frente a los 34, 3 en el grupo control, p=0,0001). Asimismo también hubo diferencias en la evaluación del dolor con valores más bajos en el grupo BRILMA. Conclusiones: En cirugía no reconstructiva de mama la realización de un bloqueo BRILMA permite obtener unas puntuaciones de dolor más bajas, lo que implica menor necesidad de rescate y un importante ahorro de tramadol en el periodo

Objective: The objective of this study is to determine whether the accomplishment of an interfascial blockade, the blocking of the cutaneous branches of the intercostal nerves in the axillary line (BRILMA) associated with a multimodal analgesic regimen improves post-operative analgesia and allows saving opioids after non-reconstructive surgery of breast. Material and methods: A prospective, randomised and simple blind study was conducted on patients that underwent non-reconstructive breast surgery. The patients were randomly assigned to the blocking group, or to the standard post-operative analgesia group (paracetamol and dexketoprofen). The main variables analysed were the pain intensity assessed by the verbal numerical scale and the analgesic rescue needs with tramadol. Results: Statistically significant differences were observed in the consumption of tramadol during the study period (10.5mg in the BRILMA group, compared to 34.3 in the control group, P=.0001). There were also differences in the pain assessment, with lower values found in the BRILMA group. Conclusions: In non-reconstructive breast surgery, performing a BRILMA block allows obtaining lower pain scores, which implies less need for rescue analgesics and a significant saving of tramadol in the study period

Prospective, randomized comparative study of ultrasound-guided blocking of the lateral cutaneous branches of the intercostal nerves versus conventional analgesia in non-reconstructive breast surgery. / Estudio prospectivo, aleatorizado comparativo entre el bloqueo guiado por ultrasonidos de las ramas cutáneas laterales de los nervios intercostales frente a analgesia convencional en cirugía no reconstructiva de mama.

OBJECTIVE: The objective of this study is to determine whether the accomplishment of an interfascial blockade, the blocking of the cutaneous branches of the intercostal nerves in the axillary line (BRILMA) associated with a multimodal analgesic regimen improves post-operative analgesia and allows saving opioids after non-reconstructive surgery of breast. MATERIAL AND METHODS: A prospective, randomised and simple blind study was conducted on patients that underwent non-reconstructive breast surgery. The patients were randomly assigned to the blocking group, or to the standard post-operative analgesia group (paracetamol and dexketoprofen). The main variables analysed were the pain intensity assessed by the verbal numerical scale and the analgesic rescue needs with tramadol. RESULTS: Statistically significant differences were observed in the consumption of tramadol during the study period (10.5mg in the BRILMA group, compared to 34.3 in the control group, P=.0001). There were also differences in the pain assessment, with lower values found in the BRILMA group. CONCLUSIONS: In non-reconstructive breast surgery, performing a BRILMA block allows obtaining lower pain scores, which implies less need for rescue analgesics and a significant saving of tramadol in the study period.

Dermal toxicity, eye and dermal irritation and skin sensitization evaluation of a new formulation of Bacillus thuringiensis var israelensis SH-14.

Bacillus thuringiensis (Bt) is the best known and most widely used of all pesticidal microbes. The aim of this study was to assess the toxicity of a new formulation of Bacillus thuringiensis var israelensis SH-14 in rats through acute dermal toxicity, dermal and eye irritation experiments. The acute dermal toxicity and dermal and eye irritation studies were performed using rabbits according to the United States Environmental Protection Agency guidelines 885.3100, 870.2500 and 870.2500, respectively. The skin sensitization study was carried out in accordance to the EPA OPPTS 870.2600 using guinea pigs. There was no mortality and no evidence of treatment-related toxicity in acute dermal toxicity test. No dermal responses, including erythema/eschar or edema, were found in rabbits treated with the new formulation of Bti SH-14. Minimum response was observed after eye application of test substance. No skin sensitization reactions were observed after the challenge with the new formulation of Bti SH-14 in the Bti SH-14-treated guinea pigs. In summary, the present study demonstrated that the new formulation of Bti SH-14 is not acutely toxic via dermal route, has low eye irritation and would not cause dermal irritation or hypersensitivity to tested animals.

Repeated dose (14 days) rat intramuscular toxicology study of Her1 vaccine.

Our goal was to assess the toxicity of two strengths (200 and 400 µg) of HER1 cancer vaccine (Center of Molecular Immunology, Cuba), presented in two different formulations, in Sprague Dawley rats after repeated intramuscular administration (14 days). Four groups (5 animals/sex) were established: Control, Placebo (adjuvant), and two Treated groups receiving a dose representing ten times of human total dose (10×), 28.6 and 57.1 µg/kg. Clinical observations, body weight and rectal temperature were measured during the study. Clinical pathology analysis was performed, besides gross necropsy and histological examination of tissues on animals at the end of the assay. The assay ended with a 100% survival. Injection site damage, with the presence of cysts and granulomas, was observed in adjuvant and vaccine treated groups, with most severe cases predominating at higher strength. Administration of Placebo and Her1 vaccine induced increase in polymorphonuclear cells, with relative lymphopenia conditioned by primary neutrophilia. In summary, results suggest that Her1 immunization was capable of inducing an inflammatory effect at the injection site, leading to systemic alterations, more significant at higher strength (400 µg, 57.1 µg/kg), probably affected by the immunizations' schedule used. The vaccine was shown to be well tolerated without any obvious signs of systemic toxicity, with findings largely attributable to the adjuvant used.

Repeated dose intramuscular injection of the CIMAvax-EGF vaccine in Sprague Dawley rats induces local and systemic toxicity.

CIMAvax-EGF consists of a human recombinant epidermal growth factor (EGF), coupled to P64k, a recombinant carrier protein from N. meningitis, and Montanide ISA 51 as adjuvant. The vaccine immunization induces a specific antibody production, inhibiting the EGF/EGF-R interaction through EGF deprivation. The objective of this study was to assess the CIMAvax-EGF toxicity in Sprague Dawley rats after intramuscular administration of repeated doses (6 months) and at the same time to determine if rat is a relevant species for studying CIMAvax-EGF vaccine. Rats were randomly distributed into four groups: control, Montanide ISA 51, treated with 1× and 15× of human total dose of the antigen. Animals were immunized weekly during 9 weeks, plus 9 immunizations every 14 days. Rats were inspected daily for clinical signs. Body weight, food consumption, and rectal temperature were measured during the administration of doses. Blood samples were collected for hematological, serum biochemical determinations and EGF titles at the beginning, three months and at the end of experimentation. Gross necropsy and histological examination of tissues were performed on animals at the end of the assay. Vaccine provoked the apparition of antibodies against EGF in the rats, demonstrating rat species relevance in these studies. Body weight gain, food and water consumption were not affected. CIMAvax-EGF and Montanide ISA 51 produced local damage at the administration site, showing multiple cysts and granulomas. Both vaccine-treated groups showed neutrophil elevation, besides an AST increase probably related to the damage at the administration site. Rectal temperature was found to be significantly higher in 15× treated group after immunizations, probably induced by the inflammatory process at the injection site. In summary, the clinical pathology findings together with the body temperature results, appear to be caused by the inflammatory reaction at the administration site of the vaccine, mainly mediated by the oil-based adjuvant Montanide ISA 51, probably enhanced by the immunological properties of the antigen. This study showed evidences that intramuscular administration during 26 weeks of CIMAvax-EGF at doses up to 15× human total dose is well tolerated in rats and it has a clinical importance since this long lasting study in relevant species allows to treat cancer patients with tumors during long periods with relative weight safety margin.

Peripheral vasodilatation determines cardiac output in exercising humans: insight from atrial pacing.

In dogs, manipulation of heart rate has no effect on the exercise-induced increase in cardiac output. Whether these findings apply to humans remain uncertain, because of the large differences in cardiovascular anatomy and regulation. To investigate the role of heart rate and peripheral vasodilatation in the regulation of cardiac output during steady-state exercise, we measured central and peripheral haemodynamics in 10 healthy male subjects, with and without atrial pacing (100­150 beats min(−1)) during: (i) resting conditions, (ii) one-legged knee extensor exercise (24 W) and (iii) femoral arterial ATP infusion at rest. Exercise and ATP infusion increased cardiac output, leg blood flow and vascular conductance (P < 0.05), whereas cerebral perfusion remained unchanged. During atrial pacing increasing heart rate by up to 54 beats min(−1), cardiac output did not change in any of the three conditions, because of a parallel decrease in stroke volume (P < 0.01). Atrial pacing increased mean arterial pressure (MAP) at rest and during ATP infusion (P < 0.05), whereas MAP remained unchanged during exercise. Atrial pacing lowered central venous pressure (P < 0.05) and pulmonary capillary wedge pressure (P < 0.05) in all conditions, whereas it did not affect pulmonary mean arterial pressure. Atrial pacing lowered the left ventricular contractility index (dP/dt) (P < 0.05) in all conditions and plasma noradrenaline levels at rest (P < 0.05), but not during exercise and ATP infusion. These results demonstrate that the elevated cardiac output during steady-state exercise is regulated by the increase in skeletal muscle blood flow and venous return to the heart, whereas the increase in heart rate appears to be secondary to the regulation of cardiac output.

Acute oral, pulmonary and intravenous toxicity/pathogenicity testing of a new formulation of Bacillus thuringiensis var israelensis SH-14 in rats.

During the last decades, efforts are being made to develop microbial insecticides as biological control agents. Bacillus thuringiensis has been one of the most consistent and significant biopesticides for using on crops as an insecticidal spray. The aim of this study was to assess and to compare the pathogenicity of a new formulation of B.thuringiensis var israelensis SH-14 in rats through oral, intranasal and intravenous single dosing. Through 21 days after administration, clinical examinations were performed daily, and body weight gain was evaluated. Clearance was estimated by means of collection of feces or examination of lungs and blood, and infectivity was evaluated enumerating microorganisms from organs of Bti SH-14 treated animals sacrificed at intervals. Gross necropsy of animals was performed at interim or final sacrifice. There were no treatment-related mortalities, and no evidence of pathogenicity or treatment related toxicity, although in the intravenous study, the microorganism was capable of achieving persistence in organs after administration, and the Bti SH-14 treated animals developed skin ulcerations and hemorrhages at the injection site. It could be concluded that the tested microorganism was not toxic or pathogenic to rats via oral or intranasal route, although it was capable of achieving persistence in organs after intravenous administration, eliciting local effects at the injection site.

Cardiovagal baroreflex and aortic hemodynamic responses to isometric exercise and post-exercise muscle ischemia in resistance trained men.

Arterial stiffness is associated with reduced baroreflex sensitivity (BRS) and resistance training; thus a potentially increased cardiovascular risk in resistance-trained (RT) individuals. The effects of resistance training on arterial stiffness and BRS have been evaluated at rest, but cardiovascular abnormalities that are not shown at rest may be revealed during recovery after exercise. Aortic systolic (aSBP) and diastolic blood pressure (aDBP), stroke volume (SV), augmentation index (AIx), vagal activity, BRS responses to isometric handgrip (IHG), and post-exercise muscle ischemia (PEMI) were evaluated in 10 RT and 10 untrained (UT) men (21+/-1 years). Resting aDBP and AIx were lower in RT compared with UT. Heart rate recovery, BRS, and vagal reactivation during PEMI were similar in both groups. Increases in aSBP (13+/-11 mmHg), AIx (5+/-10%), and SV (12+/-12%) during IHG further increased during PEMI (8+/-14 mmHg, 12+/-6%, and 10+/-8%). Increases in aDBP from rest to PEMI were higher in RT (17+/-9 mmHg) compared with UT (7+/-8 mmHg). The lower resting aDBP and the enhanced response to PEMI suggest beneficial adaptations in RT men. Wave reflection, aortic SBP, and cardiovagal BRS responses to IHG and PEMI are not affected by resistance training in young healthy men.

Evaluación de la patogenicidad en ratas del Paecilomyces lilacinus LPL-01 utilizando vías diferentes de exposición / Pathogenicity evaluation of Paecilomyces lilacinus to rats

Los nemátodos parásitos de las plantas, conocidos como plagas agrícolas desde el siglo XIX, causan un 9% de pérdidas de cultivos en los países desarrollados y un 14% en los países en desarrollo. El Paecilomyces lilacinus es un hongo parásito que ataca formas sedentarias de los nemátodos, como los huevos. Su valoración como agente microbiano de control debe incluir una evaluación de su virulencia hacia organismos no-diana, tomando en consideración las vías posibles de exposición de los humanos. Para evaluar la patogenicidad de la cepa LPL-01 del P. lilacinus en ratas, se administró por las vías oral, pulmonar e intravenosa. Las observaciones clínicas fueron diarias, y se evaluó el comportamiento del peso corporal. Se estimó el aclaramiento mediante recolección de las heces fecales y análisis de muestras de los pulmones y de la sangre, según la vía de administración, y se evaluó la infectividad mediante toma de muestras de órganos de animales inoculados sacrificados a intervalos. Durante estos sacrificios, y al final de los ensayos, se realizó la necropsia de los animales. No ocurrieron mortalidades, ni evidencias de patogenicidad relacionada con el tratamiento en los ensayos oral y pulmonar, no provocando el hongo una infestación significativa. Por vía endovenosa, el microorganismo provocó alteraciones anátomo-patológicas en hígado y bazo, coincidiendo con el período de máxima infestación. Se concluyó que la cepa LPL-01 del P. lilacinus, a las dosis evaluadas, no es patogénica por las vías oral y pulmonar, siendo levemente patogénica por vía endovenosa

Plant parasitic nematodes have been recognized as agricultural pests in Europe as early as the late 19th century. It has been estimated that plant parasitic nematodes cause crop yield losses of nearly 9% in the developed world, and over 14% in developing countries. The Paecilomyces lilacinus is a parasitic fungi attacking sedentary stages of nematodes, e.g. eggs. Evaluation of this fungus as a microbial control agent, must include an evaluation of its virulence towards non-target organisms, especially vertebrates, with consideration given to potential human exposure scenarios. With the aim of assessing the pathogenicity in rats of the strain LPL-01 of Paecilomyces lilacinus, this fungus was given using several routes of exposure (oral, pulmonary and intravenous route). In all of the assays, clinical examinations were performed daily after administration, and body weight gain of animals was evaluated. Clearance was estimated by means of collection of feces and examination of lungs and blood, depending on the route used, and ineffectiveness was evaluated by enumerating microorganisms from organs and corporal fluids in animals sacrifice at intervals. A gross necropsy of all animals was performed at interim or final sacrifice. There were no mortalities, and no evidence of pathogenicity or treatment-related toxicity either in oral or pulmonary toxicity/pathogenicity tests, without significant infection of test animals. In the intravenous toxicity/pathogenicity test, P. lilacinus caused anatomopathological changes in liver and spleen at the same period when higher infectivity was achieved. It was concluded that P. lilacinus is not pathogenic by oral and pulmonary route, but has some pathogenic effects when intravenous injection is performed

Alteraciones patológicas producidas por la inoculación subcutánea de los extractos alergénicos de Blomia tropicalis y Dermatophagoides siboney en ratas y ratones / Pathological changes due to subcutaneal administration of Dermatophagoides siboney and Blomia tropicalis allergenic extracts in rats and mice

Los extractos alergénicos se emplean en tratamientos de inmunoterapia, ya que son capaces de inducir cambios inmunológicos en la respuesta alérgica, reduciendo los síntomas clínicos de la enfermedad. Estas preparaciones terapéuticas se aplican directamente al hombre, por lo que nos propusimos como objetivo de este trabajo evaluar los cambios patológicos producidos por la administración subcutánea durante 28 días del extracto alergénico de Dermatophagoides siboney y Blomia tropicalis en ratas y ratones. Se encontraron lesiones circunscritas en la hipodermis del lugar de aplicación y caracterizadas por abundantes células redondas: linfocitos, células plasmáticas y macrófagos, agrupadas fundamentalmente alrededor de los vasos sanguíneos y terminaciones nerviosas, así como algunos leucocitos polimorfonucleares de tipo neutrófilo y células cebadas. Se concluye que la administración repetida de los extractos alergénicos de Dermatophagoides siboney y Blomia tropicalis en ratas y ratones no provoca alteraciones patológicas. (AU)

Toxicity of a GM3 cancer vaccine in Macaca fascicularis monkey: a 12-month study.

GM3 is a ganglioside that has been biochemically identified as dominating the cell surface of several human tumours, but is also found on human normal cells at much lower density. Since GM3 is widely distributed in essentially all types of animal cells, there is a conflict with the concepts of tumour-associated antigen, immunogen, and toxicity. We have designed a GM3-based cancer vaccine for the treatment of human breast and melanoma tumours. Prior to the Phase I clinical trial, we carried out a 12-month dose repeated toxicity study in five male Macaca fascicularis monkeys. Four male monkeys were treated with placebo in a similar way. During the study, no differences were observed between control and treated monkeys related to daily clinical observations (other than local damage) including rectal temperature, blood pressure, respiratory and cardiac rates, weight gain, biochemical and hematological parameters (with the exception of transitory pathological changes), and anti-DNA and anti-nuclear antibodies, although treated monkeys consistently developed both IgM- and IgG-specific anti-GM3 antibodies. Sixty per cent of treated monkeys developed moderate local reactions at the injection site, which disappeared without sequels. We concluded that this GM3 cancer vaccine overcame in monkeys the natural tolerance to GM3 ganglioside evidenced by a strong immune response, while the local reactions elicited-were transitory without apparent important systemic toxicity effects.

Occurrence and clinical correlates of psychiatric co-morbidity in delusional disorder.

The present study investigated the occurrence and the clinical correlates of psychiatric co-morbidity in a sample of 64 patients with delusional disorder (DD). Subjects were evaluated with a semi-structured interview for the collection of demographic and clinical features of the disorder; co-morbid axis 1 disorders were determined according to the clinical interview using DSM-IV by Othmer and Othmer. Delusional disorder subjects with and without co-morbid diagnoses were compared to investigate whether the presence of another psychiatric disorder influenced the clinical features of the illness.Seventy-two percent of the subjects had at least one additional lifetime psychiatric diagnosis. High lifetime co-morbidity was found with affective disorders, whose onset generally had been subsequent to the onset of DD. Patients with at least one co-morbid disorder (N = 46) had an earlier age at onset, presented for the first psychiatric consultation at an earlier age, and were younger at index evaluation for this study with respect to patients without co-morbidity (N = 18). Types of DD differed significantly according to the presence/absence of lifetime co-morbid disorders: DD patients with co-morbidity were in most cases persecutory type (54.4%) while DD patients without co-morbidity were mixed type (66.7%). Our data indicate that there is a considerable proportion of patients whose DDr is strictly connected with other co-occurring psychiatric disorders (mainly affective disorders), which exert an influence on the phenomenology of the illness.

Radiotoxicity of h-R3 monoclonal antibody labeled with 188Re administered intracerebrally in rats.

Brain tumors are often incurable despite current aggressive treatment modalities. Regional intracerebral administration of labeled monoclonal antibodies (Mabs) can maximize the radioisotope and Mab concentration to tumor sites while reducing systemic toxicity. h-R3 is a humanized antiepidermal growth factor receptor Mab that successfully targets the epidermal growth factor receptor, which is overexpressed in glioblastomas. We studied the acute local and systemic toxicity effects of intraventricular 188Re-h-R3 in rats. Forty rats were distributed into four groups with five animals of each sex in each group. A single 5 -microl dose (2.5 microl into the left and 2.5 microl into the right lateral ventricles) of neutral solution containing 50 microg of h- R3 labeled with 49.5 +/- 1.7,284 +/- 13.7 or 579 +/- 23.7 muCi of 188Re were stereotactically administered to each animal. Control animals received vehicle alone. Each animal was observed twice daily for detection of toxicity signs. Body weights were recorded on days 0, 7 and 14. Blood samples for analysis of hematological and clinical chemistry parameters were taken on days 0 and 14. Necropsy and histopathological studies were carried out after completion of the study. All animals, but one, remained clinically stable. Toxicities included local radionecrosis, discrete increase in ALAT and creatinine blood values at higher dose level. We concluded that a single intraventricular administration of relatively large doses of 188Re-h-R3 is tolerable and causes minimal local and systemic toxicity effects in rats. Nevertheless, further studies are necessary to discard learning and behavioral problems.

Radiotoxicity of h-R3 monoclonal antibody labeled with 188Re administered intracerebrally in rats

Brain tumors are often incurable despite current aggressive treatment modalities. Regional intracerebral administration of labeled monoclonal antibodies (Mabs) can maximize the radioisotope and Mab concentration to tumor sites while reducing systemic toxicity. h-R3 is a humanized antiepidermal growth factor receptor Mab that successfully targets the epidermal growth factor receptor, which is overexpressed in glioblastomas. We studied the acute local and systemic toxicity effects of intraventricular 188Re-h-R3 in rats. Forty rats were distributed into four groups with five animals of each sex in each group. A single 5- µl into the right lateral ventricles) of neutral solution containing 50 µg of h-R3 labeled with 49.5ñ1.7, 284ñ13.7 ir 579ñ23.7 µCi of 188Re were stereotactically administered to each animal. Control animals received vehicle alone. Each animal was observed twice daily for detection of toxicity signs. Body weights were recorded on days 0,7 and 14. Blood samples for analysis of hematological and clinical chemistry parameters were taken on days 0 and 14. Necropsy and histopathological studies were carried out after completion of the study. All animals, but one, remained clinically stable. Toxicities included local radionecrosis, discrete increase in ALAT and creatinine blood values at higher dose level. We concluded that a single intraventricular administration of relatively large doses of 188Re-h-R3 is tolerable and causes minimal local and systemic toxicity effects in rats. Never-theless, further studies are necessary to discard learning and behavioral problems(AU)

Hepatitis B surface antigenaemia in Ilorin, Kwara State, Nigeria.

OBJECTIVE: To determine the prevalence of HBsAg among blood donors in Ilorin, in the middle belt area of Nigeria. DESIGN: Cross sectional. SETTING: University of Ilorin Teaching Hospital. SUBJECTS: 100 patients from antenatal clinic, 100 patients from STD clinic and 295 healthy blood donors from UITH. MAIN OUTCOME MEASURES: Prevalence of HBsAg. RESULTS: One hundred and sixteen (23.4pc) of the subjects were positive for HBsAg. These included 16pc of ANC patients, 36pc of STD patients and 21.7pc of blood donors. The positivity rate among STD patients was significantly higher than among ANC patients (p < 0.01) and blood donors (p < 0.01). The positivity rate among patients above 34 years of age was higher than in those of 15 to 34 years. CONCLUSION: The above positivity rates are higher than those previously reported in Nigeria and may indicate increasing prevalence. The highest rate found among STD clinic patients may have identified them as a reservoir group to which control programmes need to be targeted.