Gum arabic promotes rat jejunal sodium and water absorption from oral rehydration solutions in two models of diarrhea

BACKGROUND & AIMS

We have shown that addition of gum arabic (GA) to a 90 mmol/L sodium-111 mmol/L glucose oral rehydration solution (ORS) enhances its effectiveness for water and electrolyte absorption in normal rats. The present study extends these observations on GA in ORS to two rat models of diarrheal disease.

METHODS

Juvenile rats were either treated for 1 week with magnesium citrate-phenolphthalein to produce chronic osmotic-secretory diarrhea or luminally exposed to 10 mmol/L theophylline to induce jejunal secretion. In both models jejunal perfusion was used to assess absorption.

RESULTS

Addition of 2.5 or 5.0 g/L GA to ORS increased roughly twofold absorption of sodium, potassium, and water in the model of chronic osmotic-secretory diarrhea. Rats perfused with GA-supplemented ORS showed an expansion of the basolateral intercellular spaces between villus absorptive epithelial cells and the lamina propria, reflecting enhanced water and sodium absorption. Similarly, addition of 2.5, 5.0, or 10.0 g/L GA to the ORS neutralized theophylline-induced abolition of net sodium and potassium absorption and reversed water and glucose malabsorption.

CONCLUSIONS

These experimental studies in models of diarrhea suggest that GA may be a useful additive to ORS for the potentiation of water and electrolyte absorption.

L-arginine in low concentration improves rat intestinal water and sodium absorption from oral rehydration solutions

BACKGROUND

The nitric oxide (NO) precursor L-arginine has been shown to produce variable effects on intestinal absorptive function, including ion transport.

AIMS

To determine whether there is an optimal concentration of L-arginine, promoting proabsorptive effects from oral rehydration solutions (ORS) with 90 or 60 mM sodium.

SUBJECTS AND METHODS

In vivo perfusion of rat jejunum with determination of net water absorption, unidirectional fluid exchanges, sodium and calcium transport, and glucose absorption.

RESULTS

L-Arginine (1 mM) added to the 90 mM sodium ORS increased intestinal absorption of both sodium and water. Higher concentrations of L-arginine (2 to 10 mM) lacked this stimulatory effect. At 20 mM, L-arginine decreased sodium absorption below baseline. With a 60 mM sodium ORS, 2 mM L-arginine had a maximal fluid and electrolyte proabsorptive effect. At 20 mM L-arginine, net water absorption was indistinguishable from that obtained in the absence of L-arginine, and lower than with 2 mM L-arginine. Sodium absorption remained raised above baseline in perfusions with 10 and 20 mM L-arginine. Morphologically, villi from perfusions with increased absorption showed a large expansion of intercellular and lamina propria intercellular spaces.

CONCLUSIONS

Low concentrations of L-arginine seem to stimulate water and electrolyte absorption by the small intestine. This effect is consistent with NO induced vasodilation, may be vaso-constrictive and thereby reverse fluid and electrolyte transport.

Dual role of HIV Tat in regulation of apoptosis in T cells

Apoptosis has been suggested to be one of the major mechanisms of depletion of CD4+ T cells in HIV-1-infected individuals. Remarkably, HIV-1-infected cells appear protected from apoptosis, whereas bystander cells show increased apoptosis in lymph nodes of infected individuals. In this work, we present evidence that the trans-activating protein of HIV-1, Tat, has a dual role in regulation of apoptosis in T cells. While addition of exogenous Tat protein induced apoptosis in uninfected T cells, T cell clones stably expressing the Tat protein were protected from activation-induced apoptosis. The addition of exogenous Tat potentiated anti-CD3 mAb, anti-Fas IgM mAb, and TNF-alpha-induced apoptosis of T cells. Pretreatment of Tat with anti-Tat Ab abrogated Tat-induced apoptosis, but did not affect anti-Fas IgM Ab-induced apoptosis. Endogenously expressed Tat was analyzed in Jurkat T cell clones transfected with either full-length tat gene (101 amino acids), or in control cells containing an empty vector. The Tat101-transfected clones were resistant to anti-CD3-induced apoptosis, when compared with cells transfected with vector alone. Furthermore, cross-linking of CD4 molecules on T cells with gp160 and anti-gp160 Ab showed markedly decreased apoptosis in Tat101 cells compared with that induced in cells transfected with vector alone. Taken together, our results indicate that HIV-1 Tat can regulate apoptosis that may contribute to the immunopathogenesis of AIDS.

Dual role of HIV Tat in regulation of apoptosis in T cells

Apoptosis has been suggested to be one of the major mechanisms of depletion of CD4+ T cells in HIV-1-infected individuals. Remarkably, HIV-1-infected cells appear protected from apoptosis, whereas bystander cells show increased apoptosis in lymph nodes of infected individuals. In this work, we present evidence that the trans-activating protein of HIV-1, Tat, has a dual role in regulation of apoptosis in T cells. While addition of exogenous Tat protein induced apoptosis in uninfected T cells, T cell clones stably expressing the Tat protein were protected from activation-induced apoptosis. The addition of exogenous Tat potentiated anti-CD3 mAb, anti-Fas IgM mAb, and TNF-alpha-induced apoptosis of T cells. Pretreatment of Tat with anti-Tat Ab abrogated Tat-induced apoptosis, but did not affect anti-Fas IgM Ab-induced apoptosis. Endogenously expressed Tat was analyzed in Jurkat T cell clones transfected with either full-length tat gene (101 amino acids), or in control cells containing an empty vector. The Tat101-transfected clones were resistant to anti-CD3-induced apoptosis, when compared with cells transfected with vector alone. Furthermore, cross-linking of CD4 molecules on T cells with gp160 and anti-gp160 Ab showed markedly decreased apoptosis in Tat101 cells compared with that induced in cells transfected with vector alone. Taken together, our results indicate that HIV-1 Tat can regulate apoptosis that may contribute to the immunopathogenesis of AIDS.

Placental copper transport in the rat. II: Effect of maternal copper deficiency

Copper (Cu) placental transport presents a steep downhill gradient from mother to fetus. This process could be altered by low-molecular-weight (LMW) ligands and maternal Cu deficiency. We compared the ratio of Cu transfer from dam-to-fetus in Cu-deficient (CuDf) and Cu-sufficient (CuSf) rats in the last day of gestation. Anaesthetized dams were iv injected 79 mumol/kg (5 mg/kg) of either Cu acetate [Cu (AcO)2]; Cu+L-histidine, 1:10. [Cu(His)10]; Cu-(glycyl-glycyl-L-histidine) [Cu(GGH)], or saline. Dam and fetal blood, as well as placentae were obtained at 0, 10, 20, 40 and 60 min. At time 0, CuDf dams had lower plasma Cu than CuSf dams (8.3 +/- 1.2 versus 26.7 +/- 1.1 mumol/l), but CuDf fetuses plasma Cu was unchanged. This resulted in a more favourable mean fetal: maternal plasma Cu ratio in the CuDf fetuses (0.61) than in the CuSf fetuses (0.21). Dam plasma Cu was unaffected by the chemical form of Cu injected. In CuDf fetuses lower plasma Cu was observed with Cu(GGH) and Cu (His)10 at 20 min than in the CuSf. In the presence of these LMW ligands CuDf placentae retained more Cu than those of the CuSf group. CuDf was associated ultrastructurally with extensive lipid deposition in dam hepatocytes and, to a lesser extent, in CuDf fetal liver. These results indicate that in CuDf, LMW ligands increase placental uptake of Cu, without improving placenta-fetus transport. Although the rat fetus is well adapted to intrauterine CuDf, it may also be susceptible to hepatic lipid infiltration when the dam is CuDf.

Oral rehydration solutions: enhanced sodium absorption with gum arabic

OBJECTIVE

To assess whether the addition of gum arabic (GA) to oral rehydration solutions (ORS) of either 60 or 90 mM sodium enhances net water and sodium absorption in rats.

METHODS

Perfusion of a jejunal segment of male juvenile rats under anesthesia, and determination of net water and sodium absorption, and unidirectional fluid movements using appropriate markers.

RESULTS

Addition of 5 and 10 g/L of GA increased the rates of sodium removal from the intestinal lumen perfused with ORS containing either 60 or 90 mM sodium. Net water absorption was unaffected, although GA tended to facilitate bidirectional fluid movement. The alteration of solute transport rates by the addition of 10 g/L GA was associated with an expansion of the basolateral intercellular spaces.

CONCLUSIONS

A soluble fiber such as GA appears to be an effective enhancer of sodium absorption from ORS when tested in experimental animals. Since GA does not affect viscosity, an alteration of solute diffusibility through the brush border membrane and changes in intercellular compartments may underlie the observed improvement of sodium absorption.

An agent cleaving glucose-derived protein crosslinks in vitro and in vivo

Glucose and other reducing sugars react with proteins by a nonenzymatic, post-translational modification process called nonenzymatic glycosylation or glycation. The sugar-derived carbonyl group adds to a free amine, forming a reversible adduct which over time rearranges to produce a class of products termed advanced-glycation end-products (AGEs). These remain irreversibly bound to macromolecules and can covalently crosslink proximate amino groups. The formation of AGEs on long-lived connective tissue and matrix components accounts largely for the increase in collagen crosslinking that accompanies normal ageing and which occurs at an accelerated rate in diabetes. AGEs can activate cellular receptors and initiate a variety of pathophysiological responses. They modify an appreciable fraction of circulating low-density lipoproteins preventing uptake of these particles by their high-affinity tissue receptors. Advanced glycation has also been implicated in the pathology of Alzheimer's disease. Because AGEs may form by a pathway involving reactive alpha-dicarbonyl intermediates, we investigated a potential pharmacological strategy for selectively cleaving the resultant glucose-derived protein crosslinks. We now describe a prototypic AGE crosslink 'breaker', N-phenacylthiazolium bromide (PTB), which reacts with and cleaves covalent, AGE-derived protein crosslinks. The ability of PTB to break AGE crosslinks in vivo points to the importance of an alpha-dicarbonyl intermediate in the advanced glycation pathway and offers a potential therapeutic approach for the removal of established AGE crosslinks.

Nonteratoid medulloepithelioma of the retina with electron microscopic and immunohistochemical characterization

Medulloepitheliomas are rare intraocular tumors, predominant in children, and originate mainly from undifferentiated nonpigmented epithelium of the ciliary body. These tumors rarely involve the optic nerve or the retina. They are classified as nonteratoid and teratoid types; the latter contains heterologous tissues. The teratoid variant of medulloepitheliomas involving the optic nerve or the retina is reported in four patients only. We describe the first case of a benign nonteratoid medulloepithelioma of the retina in a 3 1/2-year-old girl with immunohistochemical and electron microscopic characterization.

Relationship between hairy cell leukemia variant and splenic lymphoma with villous lymphocytes: presentation of a new concept

An unusual case of low-grade B-cell lymphoproliferative disorder with peripheral lymphocytosis and splenomegaly followed for 4 1/2 years is reported. During this period, the phenotype of the tumor cells in the blood changed from that of hairy cell leukemia (HCL)/chronic lymphocyte leukemia (CLL) to HCL/prolymphocytic leukemia (PLL), to PLL. The lymphoid population in the blood showed a mixture of hairy cells, villous lymphocytes, small lymphocytes, and prolymphocytes, corresponding to the phenotypes at various stages. Although relatively specific markers for CLL, HCL, and PLL, such as CD5, CD11c, CD22, CD25, and FMC-7, were positive at various stages, all these markers have also been demonstrated in a large study series of splenic lymphoma with villous lymphocytes (SLVL). In addition, the histologic pattern of the bone marrow biopsy and splenectomy specimen were not typical for HCL. This case can therefore be classified either as HCL variant or as SLVL. As SLVL assumes various cytologic and histologic patterns, which overlap with different lymphoproliferative disorders, especially HCL variants, this entity appears to represent a heterogeneous group of lymphomas/leukemias that may evolve into each other. The absence of activation of c-myc and bc1-2 oncogenes as well as mutation of p53 tumor suppressor gene, together with the presence of only one single rearranged band for both heavy chain and kappa light chain genes in our case suggest that these morphologically different lymphoid tumors may belong to the same family.

Aluminosilicates enhance the infectivity of cytomegalovirus in urine using centrifugation-enhanced antigen detection technology

Due to the inherent lability of CMV, necessary laboratory identification of this infectious agent is often compromised by a delay in specimen transport. Previous studies have addressed the phenomenon of infectivity enhancement/reduction in the rate of infectivity loss by the incorporation into various viral assay systems of trace concentrations of the adsorbents montmorillonite (bentonite [M]) or kaolinite (kaolin [K]). We extended these studies to the clinical setting to identify whether such aluminosilicates would effect an enhanced level of CMV infectivity. The shell vial assay-indirect immunofluorescent assay (SVA-IFA) was utilized in comparative testing throughout this study. The addition of trace concentrations of M or K to the SVA-IFA was found to enhance the infectivity of CMV in urine by 115 and 126%, respectively. The total CMV detection rate by SVA-IFA was 29% (30/105). Three of the 30 (10%) CMV positive specimens were detected only in shell vials which had been supplemented with K or M. Two specimens were isolation positive alone. The addition of K or M to shell vials immediately prior to the start of the SVA-IFA has the potential of (a), enhancing assay readability by increasing the number of fluorescent focus units per vial monolayer and (b), of detecting positive urine specimens with low viral titers which might otherwise not be identified using the conventional SVA-IFA procedure.

Light and electron microscopic identification of Cyclospora species in the small intestine. Evidence of the presence of asexual life cycle in human host

This is the first case of cyclosporiasis in which the parasite was clearly demonstrated in a duodenal biopsy by light microscopy. Electron microscopy identified the stages of sporozoite, trophozoite, schizont, and merozoite. Although only asexual forms were identified in our case, the sexual cycle must have taken place in the human host, because oocysts were detected in stools of the patients. Therefore, it appears that Cyclospora species require only a single host to complete its entire life cycle. Despite the heavy infection, only enterocytes were invaded. The lamina propria and submucosa were not involved. The morphology of Cyclospora in the intestine is similar to that of Isospora, but differs from that of Cryptosporidium. The morphology of the oocyst of Cyclospora resembles that of Cryptosporidium, but differs from that of Isospora. Thus, a combined study of both stool and intestinal biopsy should readily distinguish Cyclospora from Cryptosporidium and Isospora.

Intrathoracic pleomorphic liposarcoma in a child: study of an unusual case

Primary intrathoracic liposarcoma is an extremely rare neoplasm in the pediatric age group. We report an unusual case of a 3-year-old boy who presented with a large intrathoracic tumor arising from the right chest wall. Biopsy showed a pleomorphic sarcoma with histological, immunohistochemical, and ultrastructural features of pleomorphic liposarcoma. The tumor displayed an aggressive clinical behavior, and the patient continued to have recurrences despite rigorous chemotherapy and radiation treatment. He subsequently died 2 years after the initial diagnosis.

Effect of insulin-like growth factor I in murine muscular dystrophy

In muscular dystrophy there is an imbalance between muscle protein synthesis and protein degradation, resulting in net muscle catabolism and progressive muscle weakness and wasting. Both insulin and insulin-like growth factor I (IGF-I) are known to have an anabolic effect on skeletal muscle, which is believed to be enhanced in the presence of elevated concentrations of amino acids. We examined the effects of 4-week administration of recombinant human IGF-I (rhIGF-I), both alone and supplemented with a high protein diet (HPD), on muscle metabolism, morphology, and function in the 129 ReJ dystrophic mouse. rhIGF-I significantly reduced muscle protein degradation (P < 0.001), increased muscle protein content (P < 0.05), decreased fiber area variability (P < 0.01), and increased hind limb utilization (P < 0.01). Supplementation of rhIGF-I therapy with a HPD resulted in a significant increase in muscle protein synthesis (P < 0.05) in addition to a further increase in the above parameters. We conclude that rhIGF-I causes an improvement in muscle metabolism, morphology, and function in dystrophic mice, and this effect is further enhanced by the presence of a HPD.

Morphological factors influencing transepithelial conductance in a rabbit model of ileitis

BACKGROUND & AIMS

Infection of rabbits with coccidia (Eimeria magna) causes chronic ileal inflammation and diarrhea. Inflamed ileum also shows decreased transmural conductance. The aim of this study was to characterize morphological factors known to affect paracellular permeability that may alter transmural conductance in inflamed ileum.

METHODS

Ileal mucosa was mounted in Ussing chambers for study of [3H]mannitol and [3H]inulin fluxes. Light and electron microscopy were used for morphometric studies. Alterations in the zonula occludens of epithelial cells were evaluated in freeze-fracture replicas.

RESULTS

Inflamed ileum showed diminished paracellular fluxes. Inoculated rabbits showed marked lymphoplasmocytic infiltration and villus blunting in ileum. Villus linear junctional density was unaffected. However, total villus apical surface area per square centimeter of tissue was reduced in inflamed ileum, causing a diminished total villus linear junctional pathway per square centimeter of apical surface. Villus zonula occludens strand number was reduced in inflamed ileum, whereas the frequency of both villus and crypt lateral surface extrajunctional strands increased.

CONCLUSIONS

Chronic inflammation exerts a profound effect on ileal paracellular permeability. Morphological data suggest that this effect may be caused in part by alterations in inflamed ileal mucosal structure and tight junctional organization and density, particularly on villi.

Acute agranular CD4-positive natural killer cell leukemia. Comprehensive clinicopathologic studies including virologic and in vitro culture with inducing agents

BACKGROUND

A 63-year-old male presented with fever, a subcutaneous nodule, gingival hypertrophy, lacrimal gland enlargement, and no lymphadenopathy or hepatosplenomegaly, but had anemia, thrombocytopenia, and peripheral blood (PB) plus bone marrow (BM) involvement by leukemic cells. There was minimal response to multiagent chemotherapy and local radiotherapy, with a survival of 6.5 months from disease diagnosis.

METHODS

The PB and/or BM leukemic cells were evaluated using electron microscopy (EM), immunohistochemistry, flow-cytometric immunophenotyping, cytochemistry, cytogenetics, Southern blot analysis for gene rearrangement and Epstein-Barr virus (EBV), polymerase chain reaction for EBV and human herpes virus-6 (HHV-6), and in vitro culturing with inducing agents.

RESULTS

The leukemic cells were agranular and monocytoid, with a hairy cell-like bone marrow biopsy infiltrate. Myeloperoxidase (MPO) and alpha-naphthyl butyrate esterase staining was negative, and periodic acid-Schiff staining was positive by light microscopy. Electron microscopy showed MPO negativity and a lack of parallel tubular arrays. The immunophenotype was CD3-, CD56+, CD4+, CD8-, CD15+, TCR1-, and TCR2-, with germline immunoglobulin and T-cell receptor genes and an abnormal karyotype (44XY, 5q-, -13, 13q+, -15). No genomic material for EBV or HHV-6 was detected. Cell cultures with butyrate and N,N-hexamethylene bis-acetamide suggested the possible induction of tumor cells to express a T-cell immunophenotype.

CONCLUSION

A case of clonal acute natural killer (NK) cell leukemia with an unusual morphology (agranular) and unique phenotype (CD3-, CD56+, CD4+, CD15+) is presented. Unlike as in other acute NK leukemias, EBV was negative; there was no evidence of HHV-6. The tumor cell, after culturing with differentiating agents, may have been induced to express a T-cell immunophenotype.

Pleomorphic rhabdomyosarcoma of the heart metastatic to bone. Report of a case with fine needle aspiration biopsy findings

Pleomorphic rhabdomyosarcoma is an extremely rare and highly malignant neoplasm. We report an unusual case of a 14-year-old boy with skeletal metastases from a primary cardiac tumor. Fine needle aspiration biopsy of a lytic lesion in the right iliac wing showed a pleomorphic population of clusters and single cells with hyperchromatic nuclei; granular, pink cytoplasm; and isolated, large cells with whiplike or globoid cytoplasmic processes and occasional striations. Histologic, ultrastructural and radiologic features are also presented.

High protein diet has beneficial effects in murine muscular dystrophy

In normal muscle there is a delicate balance between muscle protein synthesis and protein degradation. It is believed that this balance is disturbed in muscular dystrophy (MD) by decreased muscle protein synthesis and/or increased muscle protein degradation, resulting in net catabolism. In an attempt to reduce or reverse this catabolism, a high protein diet (HPD, 50% protein) was fed to dystrophic mice (129/ReJ dy) for 4 wk. The effects on muscle biochemistry, muscle function and muscle morphology were compared with those in dystrophic mice fed a normal diet (NPD, 20% protein) and in nondystrophic mice (NORM) also fed the 20% protein diet. Compared with NORM mice, NPD mice demonstrated greater rates of muscle protein synthesis (P < 0.05) as measured by the incorporation of labeled phenylalanine into muscle, greater protein degradation (P < 0.01) as measured by urinary 3-methylhistidine excretion, and lower muscle protein concentration (P < 0.01). When dystrophic mice were fed HPD for 4 wk, protein degradation was lower (P < 0.01) and muscle protein concentration greater (P < 0.01) than in NPD mice. These biochemical improvements were accompanied by greater morphological uniformity of muscle fibers, higher volume density of muscle fibers per unit area of muscle (P < 0.01), and lower shape factor (P < 0.01). Functionally, HPD led to improved muscle endurance (P < 0.01) and increased hind-limb utilization (P 0.01). We conclude that in murine dystrophy, HPD decreases net muscle catabolism, principally by decreasing muscle protein degradation, resulting in improvement in muscle morphology, strength and function.

Primary adenoid cystic carcinoma of Skene's glands

A unique case of a 50-year-old woman is reported who presented with a suburethral mass in the anterior vaginal wall. The resected tumor was an adenoid cystic carcinoma arising from Skene's glands. Tumor was not involving Bartholin's glands. In addition to the typical glands and areas with cysts containing periodic acid-Schiff positive intraluminal material, less well-differentiated areas with neoplastic cells growing in a trabecular or solid pattern were also seen. Prominent perineural invasion was noted throughout the tumor. Immunostaining revealed positive reactions for cytokeratins, carcinoembryonic antigen, and focally for S-100 protein. Ultrastructural studies showed epithelial cells with well-formed basal lamina and prominent microvilli. This case illustrates an uncommon site, the Skene's glands for adenoid cystic carcinoma in the female genitourinary tract.

Morphological, ultrastructural, and genetic characterization of an unusual T-cell lymphoma in a patient with sinus histiocytosis with massive lymphadenopathy

Sinus histiocytosis with massive lymphadenopathy (SHML) is a rare benign disease of unknown etiology. It is rarely associated with malignant lymphoma. This report documents the first case of a T-cell lymphoma, which developed in a patient with a 10-year history of SHML. The disease was complicated by hypereosinophilia and massive retroperitoneal lymphadenopathy. Histological examination of a cervical lymph node biopsy during the terminal phase identified a lymphoma composed of cells with morphological plasmacytoid features. Ultrastructurally, the tumor cells showed poorly developed cytoplasm, nuclei with peripheral chromatin clumping, and inconspicuous nucleoli. Cytogenetic studies showed two related clones. On immunohistochemical staining tumor cells were positive with monoclonal antibodies (mAb) CD3 and CD45RO. Southern blotting analysis identified clonal rearrangements in the T-cell receptor (TCR) alpha, beta and gamma genes. Thus, T-cell lineage of the tumor cells was established. In situ hybridization of interleukin-2 (IL-2) and interleukin-5 (IL-5) cDNA probes on tissue sections identified the synthesis of IL-5 by the eosinophils, suggesting an autocrine pathway of eosinophilopoiesis leading to hypereosinophilia in this patient.

Mitochondrial encephalomyopathy associated with a single nucleotide pair deletion in the mitochondrial tRNALeu(UUR) gene

The investigation of pathogenic mitochondrial DNA (mtDNA) mutations has revealed a complex relation between patient genotype and phenotype. For unknown reasons, some mtDNA mutations produce specific clinical manifestations such as chronic progressive external ophthalmoplegia; myoclonic epilepsy and ragged-red fiber disease (MERRF); and mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). To enhance our understanding of the association between genotype and phenotype, we investigated a patient with mitochondrial encephalomyopathy and severe cerebral calcifications for a mtDNA mutation. There was a deletion of one of three T:A nucleotide pairs in the tRNALeu(UUR) gene of the mtDNA involving positions 3271 to 3273. Pedigree analysis suggested that this mutation may have occurred spontaneously in the proband. This analysis represents the smallest mtDNA deletion observed to date and is the first deletion identified within a mitochondrial tRNA. This observation emphasizes the importance of delineating the precise mutation responsible for an oxidative phosphorylation disease for patient diagnosis as well as for genetic counseling of maternal lineage relatives.

Advanced glycation end products induce glomerular sclerosis and albuminuria in normal rats

High levels of tissue advanced glycation end products (AGEs) that result from the spontaneous modification of proteins by glucose occur in diabetes and aging. To address the potential pathogenic role of AGEs in the glomerulosclerosis of diabetes or nephrosclerosis of aging, doses of AGE-modified rat albumin (25 mg per kg per day, i.v.) sufficient to elevate circulating AGE levels to the range of diabetic serum were administered daily to healthy rats alone or in combination with the AGE inhibitor aminoguanidine. After 5 months, the AGE content of renal tissues in AGE-treated rats rose to 50% above controls (P < 0.025), whereas serum contained 2.8-fold greater AGE levels (P < 0.025). Light and electron microscopy of kidneys from AGE-treated rats revealed a more than 50% increase in glomerular volume compared to controls (P < 0.001), significant periodic acid/Schiff reagent-positive deposits, basement membrane widening, and mesangial extracellular matrix increase and indicated significant glomerulosclerosis compared to untreated (P < 0.002) or albumin-treated controls (P < 0.002). These changes were associated with significant loss of protein (P < 0.005) and albumin (P < 0.002) in the urine of AGE-treated rats compared to controls. Cotreatment with aminoguanidine markedly limited both the structural and functional defects. These in vivo data demonstrate that AGEs influence glomerular structure and function in a manner leading to glomerulosclerosis. The effects are AGE-specific, as they are ameliorated by a pharmacological AGE inhibitor, aminoguanidine.

Intestinal microsporidiosis. Report of five cases

Five cases of intestinal microsporidiosis are reported, including one case of a heterosexual female acquired immunodeficiency syndrome (AIDS) patient, three homosexual males, and one bisexual male AIDS patients with detailed description of their clinical course. These five cases underscore the severity of immunodeficiency in patients with microsporidiosis. All patients had multiple opportunistic infections and a CD4 cell count below 100/microliters long before diarrhea developed. This is the first kinetic study of helper T-lymphocytes in cases of microsporidiosis. Diagnosis was made by duodenal biopsies stained with Brown and Brenn or Gram-Weigert technique (confirmed by electron microscopy) and by stool smears stained with a modified trichrome technique. However, the best preparation was plastic sections stained with toluidine blue, which demonstrated both the spores and plasmodia clearly. In our evaluation, Giemsa stain was also acceptable for identification of microsporidian spores in both intestinal biopsies and stool smears, but there was a failure to identify the organism on hematoxylin and eosin, acid-fast, periodic acid-Schiff, and Gomeri's methenamine silver stained preparations. Therapeutic attempts using albendazole, metronidazole, octreotide, and zidovudine (AZT) failed to eradicate microsporidia in these patients.

Giant myofibroblastoma of the male breast

Myofibroblastoma of the breast is a rare, benign neoplasm, seen predominantly in men. The gross appearance is that of a well-circumscribed nodule, characteristically small, seldom exceeding 3 cm. We report a case of giant myofibroblastoma measuring 10 cm and weighing 169 g in the breast of an 83-year-old man. Light microscopic, immunohistochemistry, and electron microscopic features are described. Histologically, these neoplasms may exhibit a varied cellularity that can be misinterpreted as sarcoma. However, they lack marked cellular pleomorphism, tumor necrosis, and mitosis and are characteristically composed of plump and long bipolar, spindly cells arranged in swirling fascicles with intervening broad collagen bands. As we report, immunostaining is strongly positive for vimentin, desmin, and muscle common antigen and negative for cytokeratins and S-100-associated protein. Electron microscopy shows predominantly cells suggestive of myofibroblastic differentiation. The patient has remained free of disease 2 years after mastectomy.