Upper gastrointestinal bacillary angiomatosis causing hematemesis: a case report.

A 38-year-old HIV-positive woman presented with massive hematemesis on initial admission to hospital. Endoscopy revealed ulcerated nodular lesions in the esophagus, stomach, and duodenum. The clinical impression was of Kaposi's sarcoma. The stomach was biopsied when the patient re-presented, and another endoscopy was performed. The biopsy showed mucosal ulceration with a proliferation of vascular channels associated with neutrophils and clumps of purplish, granular bacterial colonies, which were highlighted by a Warthin-Starry stain. The histopathological features were typical of bacillary angiomatosis. This case highlights bacillary angiomatosis involving the gastrointestinal tract at multiple sites, the cause of massive upper gastrointestinal hemorrhage that was the initial presentation of an HIV-positive patient, and the occurrence of visceral bacillary angiomatosis in the absence of cutaneous lesions.

Plasmablastic lymphoma in HIV+ patients: an expanding spectrum.

AIM: To describe an unusual human immunodeficiency virus (HIV)-associated lymphoma in uncommon sites. Plasmablastic lymphoma is a distinctive HIV-associated tumour that was first described in the jaws and oral cavity. Only two cases (stomach and lung) have been documented in extra-oral sites. MATERIALS AND METHODS: Four cases were encountered in HIV+ patients: three in the anorectal region and one which was nasal and paranasal. The cases were routinely processed and immunohistochemistry was performed on formalin-fixed paraffin-embedded tissue. RESULTS: The cases showed the typical morphological appearances of a high-grade, blastic non-Hodgkin's lymphoma (brisk mitotic activity and tingible body macrophages). In addition, some cells had a plasmacytoid appearance and paranuclear clearing. Immunophenotypically, the tumour cells were negative for LCA, CD20 and CD45RA. However, a small proportion of cells (5%) were immunoreactive for CD79a and the majority were positive with VS38c, indicative of plasma cell differentiation. Kappa light chain and IgG heavy chain restriction was also detected. CONCLUSIONS: Plasmablastic lymphoma may occur in extra-oral sites and has a characteristic immunophenotype including focal expression of CD31 by the neoplastic cells. Awareness of the absence of expression of conventional B-cell markers and its presence in unusual sites should facilitate the diagnosis of plasmablastic lymphoma in HIV+ patients.

pH, temperature and lactate production in human red blood cells: implications for blood storage and glycolytic control.

The interaction of temperature and pH in biological systems comprises two components. Temperature change may perturb the pH of solutions, and it may change the pKa of some ionizable groups that are involved in enzyme catalysis. The pH optima of single reactions and whole pathways are therefore temperature sensitive. The pH optimum of glycolysis in human red cells has been investigated only at 37 degrees C. We have measured the effect of temperature on the pH of stored blood suspensions and on the pH optimum of glycolysis in the human red cell. The pH of the cell suspensions in a traditional storage medium was 7.25 +/- 0.2 at 4 degrees C. The pH optimum of glycolysis was high (7.8-8.5) between 15 and 35 degrees C. It can be inferred from our data that human red cells are currently stored at least 0.5 pH units below the pH optimum of glycolysis at 4 degrees C. This suggestion is supported by storage experiments which showed that glycolysis at 4 degrees C was at least 1.5-fold more active at an initial pH of 7.67 versus 7.36. Equations which describe the variation in reaction velocity with pH were fitted to the pH curves for glycolysis in order to identify the ionizable groups that contribute to the effect of pH on glycolysis. It is generally accepted that hexokinase catalyses the rate-limiting step in glycolysis in the human red cell, but none of the ionizable groups implicated correspond to that involved in the hexokinase reaction.

Alternative fuels for platelet storage: a metabolic study.

We have studied the metabolism of platelets in vitro using washed platelets. Oxygen uptake and fuel utilization were measured. It was found that glucose is never oxidized to any significant extent and is always converted to lactate, regardless of oxygen availability. Oxidative metabolism fuels 70-100% of the ATP turnover, and oxygen uptake is the same whether the platelet is consuming glucose, acetate or only an unidentified endogenous fuel. When acetate is the added fuel, no endogenous fuel is oxidized, whereas the addition of glucose results in sparing of only 8% of endogenous fuel. Preliminary storage experiments using plasma-free media show that an acetate-containing buffered salt solution provided excellent storage conditions and that a medium without any exogenous fuel is better than one containing glucose. Thus we conclude that a successful storage medium should contain minimal amounts of glucose, and an oxidizable fuel such as acetate, in order to supplement the endogenous one.

Fructose formation in stored blood.

At the high glucose concentrations used in the collection and storage of donor blood the activity of the fructose-forming polyol pathway (Reaction I and II) could act to deplete NADPH and thus GSH, thereby exposing the cells to oxidative stress. Fructose levels were found to be high in red cells and the supernatant plasma of blood collected into CP2D, which contains 258 mM glucose. Elevated fructose was not produced by the polyol pathway, but was formed by the autoclaving process. A high fructose concentration sufficient to account for the fructose in donor red cells was also found in the CP2D anticoagulant and in samples of autoclaved glucose.