Activity modulation of microbial enzymes by llama (Lama glama) heavy-chain polyclonal antibodies during in vivo immune responses.

Since they were first described in 1993, it was found that recombinant variable fragments (rVHHs) of heavy-chain antibodies (HCAbs) from Camelidae have unusual biophysical properties, as well as a special ability to interact with epitopes that are cryptic for conventional Abs. It has been assumed that in vivo raised polyclonal HCAbs (pHCAbs) should behave in a similar manner than rVHHs; however, this assumption has not been tested sufficiently. Furthermore, our own preliminary work on a single serum sample from a llama immunized with a ß-lactamase, has suggested that pHCAbs have no special ability to down-modulate catalytic activity. In this work, we further explored the interaction of pHCAbs from four llamas raised against two microbial enzymes and analyzed it within a short and a long immunization plan. The relative contribution of pHCAbs to serum titer was found to be low compared with that of the most abundant conventional subisotype (IgG(1)), during the whole immunization schedule. Furthermore, pHCAbs not only failed to inhibit the enzymes, but also activated one of them. Altogether, these results suggest that raising high titer inhibitory HCAbs is not a straightforward strategy - neither as a biotechnological strategy nor in the biological context of an immune response against infection - as raising inhibitory rVHHs.

Immunobiological role of llama heavy-chain antibodies against a bacterial beta-lactamase.

In 1993, a fraction of antibodies (Abs) devoid of L chain was found naturally occurring in the Camelidae. They were found to lack L chains, as well as the first constant heavy-chain domain (CH(1)) and therefore they were named "heavy-chain Abs" (HCAbs). Subsequent studies focused on the functional, structural and biochemical properties of recombinant variable fragments (rVHHs) of HCAbs. It was stated that rVHHs have an augmented capacity to interact with "partially hidden" epitopes, like enzymes active sites, and have an increased stability to thermal and chemical aggression. It has been suggested that these unconventional Abs could represent an evolutionary advantage, being more efficient than conventional Abs to inhibit microbial enzymes, and thus exerting a more protective immune response against pathogens. The present work focuses on the immunobiological role of HCAbs, in their capacity to inhibit microbial enzymes. Two animal models were selected, comprising a model for common vertebrates without HCAbs (rabbits), and a model for vertebrates with both conventional and unconventional Abs (Lama glama). A recombinant bacterial beta-lactamase (CTX-M-2) was selected as the microbial enzymatic antigen. After conventional immunization schedules, neither serum titers nor serum inhibitory capacity showed significant differences when rabbits and llamas were compared. These results indicate that the a priori assumption that the adaptive immune system of camelids could be better "prepared" to respond to bacterial enzymes because of the presence of HCAbs, is not always accurate. Furthermore, when the different llama antibody isotypes and subclasses were purified, it was demonstrated that the inhibitory capacity of total serum was due exclusively to IgG(1). HCAbs not only failed to inhibit CTX-M-2, but instead they activated its enzymatic activity. Altogether, these results indicate that the hypotheses extrapolated from the rVHHs properties need to be revised; the real role of HCAbs in vivo remains unknown, as well as their evolutionary cause.

Cambio del isotipo en la respuesta a antígenos T independientes por co-inoculación con antígenos T dependientes / Isotype switch in the response against T independent antigens by co-inoculation with T dependent antigens

Un paradigma clásico de la inmulogía plantea que para que ocurra cambio de isotipo en los anticuerpos es condición sine qua non la presentación del antígeno a un linfócito T colaborador por parte de una célula presentadora de antígenos. En el presente trabajo se diseñó un modelo animal, ratones BALB/c, de respuesta inmune frente a dos antígenos típicos. Se utilizo dextrán como antígeno T independiente (AgTI) y seroalbúmina bovina (SAB) como antígeno T dependiente (AgTD), y se estúdio la respuesta, analizando los isotipos de los anticuerpos específicos producidos. Los resultados obtenidos muestran que la respuesta a dextrán en presencia de SAB ocurre con cambio de isotipo (swith), essencialmente de IgM a IgG. Estos experimentos sugieren que la SAB genera un entorno bioquímico inductor de cambio de isotipo tanto en supropia via de procesamiento como en del dextrán. Los resultados señalan que la asociación exclusiva de los AgTDs con las respuestas em las que ocurre cambio de isotipo es incorrecta. Considerando el modelo propuesto resulta poco probable encontrar in vivo y en forma espontÔnea casos en los que los AgTIs ingreses al organismo aislados; en cambio, es mucho más probable que el ingreso ocurra conjuntamente con AgTDs, y en consecuencia ocurra cambio de isotipo. (AU)

Cambio del isotipo en la respuesta a antígenos T independientes por co-inoculación con antígenos T dependientes / Isotype switch in the response against T independent antigens by co-inoculation with T dependent antigens

Un paradigma clásico de la inmulogía plantea que para que ocurra cambio de isotipo en los anticuerpos es condición sine qua non la presentación del antígeno a un linfócito T colaborador por parte de una célula presentadora de antígenos. En el presente trabajo se diseñó un modelo animal, ratones BALB/c, de respuesta inmune frente a dos antígenos típicos. Se utilizo dextrán como antígeno T independiente (AgTI) y seroalbúmina bovina (SAB) como antígeno T dependiente (AgTD), y se estúdio la respuesta, analizando los isotipos de los anticuerpos específicos producidos. Los resultados obtenidos muestran que la respuesta a dextrán en presencia de SAB ocurre con cambio de isotipo (swith), essencialmente de IgM a IgG. Estos experimentos sugieren que la SAB genera un entorno bioquímico inductor de cambio de isotipo tanto en supropia via de procesamiento como en del dextrán. Los resultados señalan que la asociación exclusiva de los AgTDs con las respuestas em las que ocurre cambio de isotipo es incorrecta. Considerando el modelo propuesto resulta poco probable encontrar in vivo y en forma espontânea casos en los que los AgTIs ingreses al organismo aislados; en cambio, es mucho más probable que el ingreso ocurra conjuntamente con AgTDs, y en consecuencia ocurra cambio de isotipo.

[Imaging of the transplanted liver]. / Zobrazenie transplantovanej pecene.

The study brings about the newest information on possibilities of imaging the liver, its vessels, biliary ducts and further organs in coincidence with liver transplantation. (Fig. 7, Ref. 39.)

Manual de diagnóstico ultrasónico / Manual of diagnostic ultrasound

This manual provides guidance on the use of ultrasound in the diagnosis of a wide variety of common conditions at thw primary and first-referral levels of health care. It is intended for use by doctors, sonographers, nurses and midwives with basic training in ultrasound techniques, who are working with a general-purpose scanner, and who do not have ready access to expert advice

The introductory chapters explain how ultrasound works, give advice on choosing a scanner, and describe some misleading artefacts that may occur on ultrasound images. These are followed by 17 chapters dealing with specific organs or systems of the body. Each chapter includes guidance on the indications for ultrasound examination, and describes the preparation of the patient and the techniques that are likely to be successful. Numerous ultrasound scans show both normal and abnormal conditions, and almost every scan is accompanied by a corresponding computer-generated image on which the most significant features are highlighted

Manual of diagnostic ultrasound

This manual provides guidance on the use of ultrasound in the diagnosis of a wide variety of common conditions at thw primary and first-referral levels of health care. It is intended for use by doctors, sonographers, nurses and midwives with basic training in ultrasound techniques, who are working with a general-purpose scanner, and who do not have ready access to expert advice

The introductory chapters explain how ultrasound works, give advice on choosing a scanner, and describe some misleading artefacts that may occur on ultrasound images. These are followed by 17 chapters dealing with specific organs or systems of the body. Each chapter includes guidance on the indications for ultrasound examination, and describes the preparation of the patient and the techniques that are likely to be successful. Numerous ultrasound scans show both normal and abnormal conditions, and almost every scan is accompanied by a corresponding computer-generated image on which the most significant features are highlighted

Work in progress CAVUS: transcaval ultrasonography of abdominal organs. Preliminary results.

Endoluminal sonography using tiny transducers (20 MHz) has found wide application in various fields of investigation. We have applied the same technology to the assessment of abdominal organs using the transcaval route (CAVUS). Normal vessels and both normal and dilated bile ducts were displayed. Although the procedure is simple and safe, and the images produced are excellent, to be useful clinically, microtransducers (6 or 7 MHz) will have to be developed. This technique holds much promise, and further miniaturization will allow greatly expanded use of endoluminal approaches.

[Echographic diagnosis of peritoneal metastases in patients with ascites]. / Le diagnostic échographique des métastases péritonéales chez les malades ascitiques.

A prospective study of 14 malignant ascites examined with high frequency ultrasonic probes enabled he authors to achieve a diagnosis of peritoneal metastases in 78% of cases. Peritoneal metastases appear as areas of peritoneal thickening or scalloping, as nodules, with sometimes a strong bulging, and as intestinal masses. Soft part ultrasound should be employed systematically in the diagnosis and follow up of malignant ascites.

Acute fatty liver of pregnancy: CT evaluation. Case report.

CT scans of two patients with acute fatty liver of pregnancy were reviewed in conjunction with the clinical evolution of this uncommon and potentially fatal disorder. In each of the CT scans, liver density measurements were less than those of the spleen. While the findings are non-specific, in the proper clinical context they are highly suggestive and may be the sole method of diagnosis, as these patients often have coagulation problems which rule out liver biopsy. It is an important diagnosis, as the high maternal and fetal mortality rates appear to be considerably reduced by early foetal delivery.

[Ultrasonography and x-ray computed tomography in the diagnosis of intra-abdominal textiloma. Apropos of 12 cases]. / Apport de l'échographie et de la scanographie dans le diagnostic des textilomes intra-abdominaux. A propos de 12 cas.

Feared by every surgeon, retained surgical sponges (or gossypiboma) are rare iatrogenic entities. Ultrasonography and computed tomography are very valuable, providing an immediate answer in the majority of cases. We report 12 cases of intra-abdominal retained surgical swabs. The ultrasonic pattern was made whether of a large poorly echogenic mass with a hyper-echogenic center and sharply delineated posterior acoustic shadow (7 cases) or of a large acoustic shadow posterior to a solitary highly echogenic area (4 cases). Computed tomography demonstrated whether large peripherally enhanced cystic mass associated with serpiginous or spongiform central area (5 cases) or heterogeneous abscess-like fluid mass.

[Acute fatty liver of pregnancy. Apropos of 4 cases: contribution of x-ray computed tomography]. / Stéatose hépatique aiguë gravidique. A propos de 4 cas: apport de la tomodensitométrie.

Acute fatty liver of pregnancy is a disease of the third trimester, generally considered to be rare and to have a grave prognosis. Histologically the characteristic fine droplet steatosis usually produces distinct vacuolization. Successful treatment depends on accurate diagnosis and early delivery. Computed tomography is of value in the diagnosis of fatty liver through liver and spleen attenuation value measurements. We reviewed 4 cases of acute fatty liver of pregnancy. Computed tomography was performed in two cases and was very helpful in the diagnosis of this condition.

Ultrasound study of adenopathies within the hepatoduodenal ligament: the "rosebud" pattern.

In about 10% of lymphopathies with extensive retroperitoneal adenopathies, adenopathies are also encountered within the hepatoduodenal ligament. When large, such adenopathies, which surround the portal vein, hepatic artery, and bile duct, give rise to a particular ultrasound pattern: the "rosebud pattern."