An analytical model for the dissolution of different particle size samples of Bioglass in TRIS-buffered solution

We analyzed the early stages of reactivity of three different particle size samples of Bioglass 45S5 and a bulk sample in TRIS-buffered solution at pH 8. Ion release, measured with ion-coupled plasma emission spectroscopy, and pH variations are reported. It was demonstrated that differences in the initial surface area influence the increase in pH, the rate of elemental release, and the rate of calcium phosphate reprecipitation. In particular, a thicker Ca/P layer was obtained on larger particles. The equilibrium value of Si in solution was independent of sample form and amount of sample dissolved, and was always close to the value observed when bulk silica is dissolved at pH 8. An analytical model is proposed for cation release, based on a two-step mechanism. It was found that the early stage of dissolution was nearly diffusion controlled for larger particles and bulk samples. The second stage was similar to a first-order homogeneous dissolution. The influence of sample surface area/solution volume ratio seemed to be more complex than that proposed in the early works presented in the literature. It is suggested that variation of surface area has a significant impact on the course of the dissolution.     

Transplantation of the heart in an infant and an adult

Experience with human heart transplantation is reported. A technically successful infant heart transplantation was performed on December 6, 1967. The child died 61/2 hours postoperatively in severe metabolic and respiratory acidosis.

Another heart transplantation was performed on January 5, 1968; the recipient was a 57-year old man. The donor heart was unable to support the circulation, and the patient died 101/2 hours postoperatively.

Problems in the selection of donors and of recipients, in the surgical technic, and in the postoperative management are discussed.     

Follicular mucinosis: a clinicopathologic, histochemical, immunohistochemical and molecular study comparing the primary benign form and the mycosis fungoides-associated follicular mucinosis

Objectives: To determine (i) whether primary (idiopathic) follicular mucinosis (PFM) and lymphoma‐associated follicular mucinosis (LAFM) are distinct or related entities and whether there are reliable criteria that allow the two forms to be distinguished, (ii) the histochemical properties and consequently the type of mucin that accumulates in the follicle in PFM and LAFM, and (iii) whether there is any difference between the staining properties of mucin in patients with PFM and LAFM. Methods: Thirty‐one patients were divided into two groups. Group 1 comprised 20 patients with no associated mycosis fungoides or Sézary syndrome (PFM) and group 2 was made up of the other 11 patients who had clinicopathological evidence of cutaneous T‐cell lymphoma (LAFM). The biopsy specimens of the patients were studied with histopathological, histochemical and immunohistochemical methods. Molecular biology studies were also performed. Results: Patients with PFM were more frequently younger (mean age 39 years), women (F:M=3:1), and presented with a solitary lesion involving the head/neck area more often than patients with LAFM who were older (mean age 54 years), men (M:F=2:1), and presented with multiple lesions on areas of the body other than the head/neck area. As for histopathological findings, large cystic spaces filled with mucin and a slight perivascular and periadnexal polyclonal infiltrate of mostly non‐atypical lymphocytes without epidermotropism and with an equivalent CD4+/CD8+ cell rate were more suggestive of PFM. On the contrary, patients with LAFM were more probably to present with a dense band‐like infiltrate with some atypical lymphocytes and sign of epidermotropism, a prominent CD4+ immunophenotype and a monoclonal rearrangement of the infiltrate. Mucin proved to be a dermal‐type mucin, composed of both hyaluronic acid and sulfated glycosaminoglycans. No differences were found in the composition of the follicular mucin in the PFM compared with LAFM. Conclusions: Although no single, indisputable feature can reliably differentiate PFM from LAFM and a considerable overlapping among the two groups exists, the use of multiple clinical, histological and immunopathological criteria associated with gene rearrangement analysis can be useful in evaluation of those patients.     

Single-chain antigen recognition receptors that costimulate potent rejection of established experimental tumors

Tumor cells are usually weakly immunogenic as they largely express self-antigens and can down-regulate major histocompatability complex/peptide molecules and critical costimulatory ligands. The challenge for immunotherapies has been to provide vigorous immune effector cells that circumvent these tumor escape mechanisms and eradicate established tumors. One promising approach is to engineer T cells with single-chain antibody receptors, and since T cells require 2 distinct signals for optimal activation, we have compared the therapeutic efficacy of erbB2-reactive chimeric receptors that contain either T-cell receptor zeta (TCR-zeta) or CD28/TCR-zeta signaling domains. We have demonstrated that primary mouse CD8(+) T lymphocytes expressing the single-chain Fv (scFv)-CD28-zeta receptor have a greater capacity to secrete Tc1 cytokines, induce T-cell proliferation, and inhibit established tumor growth and metastases in vivo. The suppression of established tumor burden by cytotoxic T cells expressing the CD28/TCR-zeta chimera was critically dependent upon their interferon gamma (IFN-gamma) secretion. Our study has illustrated the practical advantage of engineering a T-cell signaling complex that codelivers CD28 activation, dependent only upon the tumor's expression of the appropriate tumor associated antigen.