Behavior of plasma hemoglobin in an experimental model of occlusive mesenteric ischemia

The difficulties in establishing the diagnosis of mesenteric ischemia are responsible for the high mortality rate that is associated with this clinical condition. We studied the behavior of plasma hemoglobin in an experimental model of occlusive mesenteric ischemia in mice. Our results showed a clear relationship between the duration of ischemia and plasma hemoglobin levels. With regard to the time frames studied (3 hours, 6 hours, 12 hours, and 24 hours), comparison with control groups produced calculated P values of less than 0.01 for all time frames with the exception of the 3-hour group. This test may have the potential to aid in the diagnosis of mesenteric ischemia as well as the follow-up of its course after various therapeutic approaches.

SPECT-based tailoring of psychosurgical procedures: is it possible?

In contrast to the other areas of functional neurosurgery, psychosurgery has remained basically empiric and unchanged since the seventies, except for the recent suggestion to use chronic stimulation instead of ablative surgery. In this study, the authors investigated the value of SPECT abnormalities to guide psychosurgery and correlated the surgical results with the postoperative SPECT. This new approach, SPECT-based tailored psychosurgery, was applied in 4 of 11 patients referred for surgery, who fulfilled the inclusion criteria adopted. Excellent results were obtained in all of them after a follow-up of 30-52 months. Postoperative SPECT normalized in every case. We conclude, based on this small series, that it is possible to individualize and lateralize (tailor) psychosurgical procedures for every patient and that, to achieve this goal, SPECT is a rather impressive means and that postoperative SPECT closely correlated with the surgical results.

[Oral manifestations, CD4+ T-lymphocytes count and viral load in Brazilian and North-American HIV-infected children]

Oral manifestations related to HIV infection were evaluated in 184 children of both genders, aging 0-13 years. The oral exams were carried out at the Ambulatory of Pediatric AIDS, São Lucas Hospital and at the Clinics Hospital, both in Porto Alegre, RS, Brazil, and at the University Hospital and School of Dentistry, State University of New York, Stony Brook, NY, USA, from January 1999 to May 2000. A high prevalence of oral manifestations was observed both in Brazilian (72.73%) and American (53.66%) children. The most frequent manifestations were cervical lymphadenopathy, swelling of the parotids, erythematous candidiasis, petechia, gingivitis, xerostomia and angular cheilitis. Children with oral manifestations had almost normal counts of CD4+ T lymphocytes and high viral load.

Method to obtain endoscopic esophageal samples for primary cell culture: focus on infectious contamination

Cell culture techniques hold great importance for the development of molecular biology. However, when used to study oncology, most of the samples come from surgical specimens. Endoscopy is a interesting alternative to get samples for culture. We studied a protocol to allow the control of infectious contamination potentially related to endoscopy, which could preclude it as a method to obtain cells for culture. Esophageal biopsies from 30 patients were taken through upper gastrointestinal endoscopy, using a previously flamed forceps, and were cultivated with and without amphotericin. Our results showed contamination in 3.3% of the wells without the antifungal and in 0.8% of those with it. Regarding the 30 cases studied, the described protocol was able to provide samples free of contamination in all of them.

Protein and cell engineering of components of the human immunoglobulin E receptor/effector system: applications for therapy and diagnosis

Adaptive immune responses characterised by the synthesis of antibodies of the immunoglobulin E (IgE) isotype play an important role in type I hypersensitivity disorders and parasitic infestations, diseases which have an significant socioeconomic impact world-wide. This paper considers potential applications of recent advances in our understanding of the origin of isotype specific immune responses which emerged as a result of cell and protein engineering studies on components of the human IgE/receptor/effector system. Furthermore, the identification of the receptor binding regions in IgE as a result of the development of a stable assay system has important applications for the design of rational therapeutic interventions in allergy and asthma, the treatment of mast cell tumours, and the establishment of procedures for the selective isolation of cells expressing the high-affinity receptor for IgE for functional studies.

Potential allergens stimulate the release of mediators of the allergic response from cells of mast cell lineage in the absence of sensitization with antigen-specific IgE

A number of structurally diverse antigens preferentially stimulate the synthesis of IgE antibodies, but no unifying principle has been proposed that explains the nature of isotype selection. In the present study, we show that common allergens present in bee venom, house dust mite emanations and parasite proteins induce mast cell and basophil degranulation and stimulate interleukin-4 synthesis, and secretion in the absence of antigen-specific IgE. These data point to a linkage between the initial activation of cells of the innate immune system and subsequent adaptive immune responses. They suggest that IgE-independent mast cell and basophil degranulation is predictive of potential allergenicity and can be evaluated by means of a cellular assay. Our study indicates that non-immunological degranulation by prototypic allergens, such as bee venom phospholipase A2 or proteases associated with house dust mite emanations, is critically dependent on enzymatic activity. These findings have potentially important implications for vaccine design in allergic and parasitic disease.

Identification of the high affinity receptor binding region in human immunoglobulin E

We have investigated the capacity of N- and C-terminally truncated and chimeric human (h) IgE-derived peptides to inhibit the binding of 125I-labeled hIgE, and to engage cell lines expressing high and low affinity receptors (Fc-epsilon-RI/II). The peptide sequence Pro343-Ser353 of the hC-epsilon-3 domain is common to all h-epsilon-chain peptides that recognize hFc-epsilon-RI. This region in IgE is homologous to the A loop in C-gamma-2 that engages the rat neonatal IgG receptor. Optimum Fc-epsilon-RI occupancy by hIgE occurs at pH 6.4, with a second peak at 7.4. N- or C-terminal truncation has little effect on the association rate of the ligands with this receptor. Dissociation markedly increases following C-terminal deletion, and hFc-epsilon-RI occupancy at pH 6.4 is diminished. His residue(s) in the C-terminal region of the epsilon-chain may thus contribute to the high affinity of interaction. Grafting the homologus rat epsilon-chain sequence into hIgE maintains hFc-epsilon-RI interaction without conferring binding to rat Fc-epsilon-RI. hFc-epsilon-RII interaction is lost, suggesting that these residues also contribute to hFc-epsilon RII binding. h-epsilon-chain peptides comprising only this sequence do not block hIgE/hFc-epsilon-RI interaction or engage the receptor. Therefore, sequences N- or C-terminal to this core peptide provide structures necessary for receptor recognition.

A link between catalytic activity, IgE-independent mast cell activation, and allergenicity of bee venom phospholipase A2

The molecular and cellular mechanisms controlling Ab isotype selection following encounter of a given Ag are still unclear, although the regulatory role of cytokines is established. In the present study we explored the possibility that the nonimmunologic interaction of an allergen with cells of the innate immune system might result in a release of mediators that promote IgE isotype selection in adaptive responses. Using the bee venom allergen phospholipase A2 (PLA2) and a mutant variant lacking enzymatic function, we show that PLA2, but not its catalytically inactive variant, is able to induce IgE-independent mediator release, including IL-4, from rodent mast cells. Assessing the in vivo relevance of these observations, we find that repeated injections of low doses of active enzyme into mice induce the synthesis of high levels of PLA2-specific IgE, while immunization with the inactive form yields no detectable IgE response. Both Ags were similarly immunogenic when high doses of Ag were used for immunization. These findings suggest that mast cells might be a source of IL-4 at the onset of specific immunity against sources of allergens such as bee venom that contain PLA2 and support the concept that the biologic action of an Ag on cells of the innate immune system can play a role in determining adaptive immune responses.

A link between catalytic activity, IgE-independent mast cell activation, and allergenicity of bee venom phospholipase A2

The molecular and cellular mechanisms controlling Ab isotype selection following encounter of a given Ag are still unclear, although the regulatory role of cytokines is established. In the present study we explored the possibility that the nonimmunologic interaction of an allergen with cells of the innate immune system might result in a release of mediators that promote IgE isotype selection in adaptive responses. Using the bee venom allergen phospholipase A2 (PLA2) and a mutant variant lacking enzymatic function, we show that PLA2, but not its catalytically inactive variant, is able to induce IgE-independent mediator release, including IL-4, from rodent mast cells. Assessing the in vivo relevance of these observations, we find that repeated injections of low doses of active enzyme into mice induce the synthesis of high levels of PLA2-specific IgE, while immunization with the inactive form yields no detectable IgE response. Both Ags were similarly immunogenic when high doses of Ag were used for immunization. These findings suggest that mast cells might be a source of IL-4 at the onset of specific immunity against sources of allergens such as bee venom that contain PLA2 and support the concept that the biologic action of an Ag on cells of the innate immune system can play a role in determining adaptive immune responses.

Comparative study of the ultrastructural alterations in the pulmonary vessels of rats treated with alpha-naphthylthiourea (ANTU) and ammonium sulphate

A comparative study of the ultrastructural changes in rat pulmonary vessels was made in two different situtations of increased vascular permeability: one caused by alpha-naphthylthiourea (ANTU) and the other induced by ammonium sulphate (AS). AS had a more destructive effect on the capillaries but showed little alteration in vessels larger than capillaries. ANTU provoked milder ultrastructural lesions but acted on capillaries, arterial and venous structures. In both conditions intravenously injected carbon particles adhered to the vessel wall and leakage into the interstitial space was rarely seen despite the presence of endothelial gaps. It was concluded that ANTU and AS provoke different ultrastructural alterations and that pulmonary and systemic vessels react differently when undergoing changes in permeability.

Ultrastructural changes in rat lung arterioles in conditions of altered permeability

By means of the colloidal carbon technique and injection of a barium-gelatin mixture into the pulmonary artery, the ultrastructure of lung arterioles in a state of increased permeability has been studied. In certain conditions pulmonary arteriolar permeability changes are frequent and the carbon particles adhere to the endothelium. Leakage of carbon into the interstitial space is observed only rarely. It is concluded that the pulmonary and systemic vessels have different patterns of response to altered permeability.