Reconstitution of vesiculated Golgi membranes into stacks of cisternae: requirement of NSF in stack formation

We have developed an in vitro system to study the biochemical events in the fusion of ilimaquinone (IQ) induced vesiculated Golgi membranes (VGMs) into stacks of cisternae. The Golgi complex in intact normal rat kidney cells (NRK) is vesiculated by treatment with IQ. The cells are washed to remove the drug and then permeabilized by a rapid freeze-thaw procedure. VGMs of 60 nm average diameter assemble into stacks of Golgi cisternae by a process that is temperature dependent, requires ATP and a high speed supernatant from cell extract (cytosol), as revealed by immunofluorescence and electron microscopy. The newly assembled stacks are functionally active in vesicular protein transport and contain processing enzymes that carry out Golgi specific modifications of glycoproteins. The fusion of VGMs requires NSF, a protein known to promote fusion of transport vesicles with the target membrane in the exocytic and endocytic pathways. Immunoelectron microscopy using Golgi specific anti-mannosidase II antibody reveals that VGMs undergo sequential changes in their morphology, whereby they first fuse to form larger vesicles of 200-300-nm average diameter which subsequently extend into tubular elements and finally assemble into stacks of cisternae.

Infantile histiocytoid cardiomyopathy: three cases and literature review

A review is presented of the clinical and cardiac morphologic findings in 50 previously reported and 3 new patients with histiocytoid cardiomyopathy. This disorder occurs in infants and small children and is characterized clinically by severe and often fatal arrhythmias and morphologically by focal collections of altered myocytes that are roundshaped and resemble histiocytes. Sixteen patients had yellowish nodules on the endocardium, epicardium, and/or valves; the other 37 had foci of abnormal myocytes throughout the myocardium. These cells were remarkably similar in all patients and had poorly developed or absent intercellular junctions, few or no contractile elements, and markedly increased numbers of mitochondria, which imparted a granular or vacuolated appearance to the cytoplasm. There was a high prevalence of anomalies involving the nervous system and eyes and of oncocytic cells in various glands. Evidence is presented to exclude the possibilities that the disorder represents a developmental anomaly of the atrioventricular conduction system, a multifocal tumor of Purkinje cells, a developmental arrest of cardiac myocytes, and a diffuse type of mitochondrial cardiomyopathy. Histiocytoid cardiomyopathy is considered to be the result of hamartoma-like aggregations of cardiac myocytes with features similar to those of oncocytes. This syndrome is likely caused by prenatal myocardial or systemic (viral?) injury. Surgical excision of nodules of histiocytoid cells can result in clinical remission.

Golgi spectrin: identification of an erythroid beta-spectrin homolog associated with the Golgi complex

Spectrin is a major component of a membrane-associated cytoskeleton involved in the maintenance of membrane structural integrity and the generation of functionally distinct membrane protein domains. Here, we show that a homolog of erythrocyte beta-spectrin (beta I sigma*) co-localizes with markers of the Golgi complex in a variety of cell types, and that microinjected beta-spectrin codistributes with elements of the Golgi complex. Significantly, we show a dynamic relationship between beta-spectrin and the structural and functional organization of the Golgi complex. Disruption of both Golgi structure and function, either in mitotic cells or following addition of brefeldin A, is accompanied by loss of beta-spectrin from Golgi membranes and dispersal in the cytoplasm. In contrast, perturbation of Golgi structure without a loss of function, by the addition of nocodazole, results in retention of beta-spectrin with the dispersed Golgi elements. These results indicate that the association of beta-spectrin with Golgi membranes is coupled to Golgi organization and function.

Human giardiasis. A morphometric study of duodenal biopsy specimens in relation to the trophozoite count in the duodenal aspirate

We present a morphometric analysis of findings from a histopathologic study of duodenal giardiasis in relation to the trophozoite count in the duodenal aspirate. Of 30 patients with giardiasis whose conditions were studied, a mean trophozoite count of 10(3)/mL or greater was found in 21, and a mean trophozoite count of less than 10(3)/mL was found in nine--these two types of trophozoite counts in these 30 patients represented the acute phase (group 1) and the clearance phase (group 2) of giardiasis, respectively. Group 1 patients had a low mean villus height that was significantly less than that found in the control subjects. Group 2 patients had a high mean crypt depth that was significantly greater than that found in the control subjects. Partial villus atrophy was seen in only seven of the group 1 patients, including five with villus epithelial cell lesions. Groups 1 and 2 showed minor differences of an inflammatory response that was significantly greater than that shown in the control subjects.

Location of Golgi membranes with reference to dividing nuclei in syncytial Drosophila embryos

The role of cytoskeletal elements in the cellularization of syncytial Drosophila embryos is becoming evident; however, the distribution and role of organelles such as the Golgi complex, essential for membrane biogenesis, remain unknown. We have cloned a Golgi-membrane-associated polypeptide, beta-COP, from Drosophila. Immunocytochemical studies of syncytial Drosophila embryos with anti-Drosophila beta-COP antibody reveal that Golgi membranes are spatially segregated from the rapidly dividing nuclei. In early embryos, the Golgi membranes are located in the embryonic cortex and nuclei are confined to the core. This distribution of Golgi membranes may serve in preparation of the embryonic cortex for the accommodation of nuclei upon their eventual migration to the cortex and in biogenesis of the excessive plasma membrane needed for cellularization of syncytial embryos.

Role of alpha 1-adrenergic receptors in the intermediolateral column in mediating the pressor responses elicited by the stimulation of ventrolateral medullary pressor area

Microinjections of alpha 1-adrenergic receptor agonists into the intermediolateral cell column of the spinal cord (IML) elicit sympathoexcitatory responses. This observation, together with the identification of projections of epinephrine-containing cells in the rostral ventrolateral medullary pressor area (VLPA) to the IML, has prompted speculation that epinephrine may mediate pressor responses to the stimulation of the VLPA. This hypothesis was tested in pentobarbital-anesthetized, artificially ventilated, male Wistar rats. A mesenteric arterial branch was cannulated for monitoring blood pressure. Pressor responses were elicited predominantly from T8-T10 by injections (1.7 nmol/20 nl) of L-glutamate into the IML; maximum pressor responses (29.3 +/- 4 mmHg) were elicited from T9. Pressor responses were also elicited by injections of epinephrine into the IML at T9; maximum pressor effect (16.3 +/- 1.2 mmHg) was elicited by a dose of 0.05 pmol/20 nl. This effect of epinephrine at T9 was blocked by prior injections of prazosin (a selective alpha 1-adrenergic receptor blocker; 0.125 pmol/20 nl) at the same site. Stimulation of the VLPA by unilateral microinjections of glutamate elicited pressor responses (56 +/- 12 mmHg). Bilateral injections of prazosin at T8-T10, in the dose (0.125 pmol) that blocked a maximally effective dose of epinephrine, did not block the pressor responses to subsequent injections of glutamate into the VLPA. On the other hand, bilateral microinjections of AP-7 (an NMDA receptor blocker; 1 nmol/20 nl), but not DNQX (10 pmol; a non-NMDA receptor blocker), into the IML at T8-T10 blocked the pressor effects of the subsequent injections of glutamate into the VLPA.(ABSTRACT TRUNCATED AT 250 WORDS)

Microtubule independent vesiculation of Golgi membranes and the reassembly of vesicles into Golgi stacks

We have recently shown that ilimaquinone (IQ) causes the breakdown of Golgi membranes into small vesicles (VGMs for vesiculated Golgi membranes) and inhibits vesicular protein transport between successive Golgi cisternae (Takizawa et al., 1993). While other intracellular organelles, intermediate filaments, and actin filaments are not affected, we have found that cytoplasmic microtubules are depolymerized by IQ treatment of NRK cells. We provide evidence that IQ breaks down Golgi membranes regardless of the state of cytoplasmic microtubules. This is evident from our findings that Golgi membranes break down with IQ treatment in the presence of taxol stabilized microtubules. Moreover, in cells where the microtubules are first depolymerized by microtubule disrupting agents which cause the Golgi stacks to separate from one another and scatter throughout the cytoplasm, treatment with IQ causes further breakdown of these Golgi stacks into VGMs. Thus, IQ breaks down Golgi membranes independently of its effect on cytoplasmic microtubules. Upon removal of IQ from NRK cells, both microtubules and Golgi membranes reassemble. The reassembly of Golgi membranes, however, takes place in two sequential steps: the first is a microtubule independent process in which the VGMs fuse together to form stacks of Golgi cisternae. This step is followed by a microtubule-dependent process by which the Golgi stacks are carried to their perinuclear location in the cell. In addition, we have found that IQ has no effect on the structural organization of Golgi membranes at 16 degrees C. However, VGMs generated by IQ are capable of fusing and assembling into stacks of Golgi cisternae at 16 degrees C. This is in contrast to the cells recovering from BFA treatment where, after removal of BFA at 16 degrees C, resident Golgi enzymes fail to exit the ER, a process presumed to require the formation of vesicles. We propose that at 16 degrees C there may be general inhibition in the process of vesicle formation, whereas the process of vesicle fusion is not affected.

Complete vesiculation of Golgi membranes and inhibition of protein transport by a novel sea sponge metabolite, ilimaquinone

We have identified a novel natural metabolite, ilimaquinone (IQ), from sea sponges that causes Golgi membranes to break down completely in vivo into small vesicular structures (called vesiculated Golgi membranes [VGMs]). Under these conditions, transport of newly synthesized proteins from endoplasmic reticulum (ER) to the cis-Golgi-derived VGMs is unaffected; however, further transport along the secretory pathway is blocked. Upon removal of the drug, VGMs reassemble rapidly into a Golgi complex, and protein transport is restored. By employing a cell-free system that reconstitutes vesicular transport between successive Golgi cisternae, we provide evidence that the inhibition of protein transport by IQ is specifically due to an inhibition of transport vesicle formation. In addition, like brefeldin A (BFA), IQ treatment prevents the association of beta-COP and ADP-ribosylation factor to the Golgi membranes; however, unlike BFA treatment, there is no retrograde transport of Golgi enzymes into ER.

Apple juice malabsorption: fructose or sorbitol?

Carbohydrate malabsorption after apple juice ingestion may produce abdominal symptoms and diarrhea, especially in children. The carbohydrates suggested to play roles in this process are fructose, as it is present in excess of glucose, and sorbitol. Absorption of the carbohydrates in apple juice was investigated in 17 children and 12 adults by means of the hydrogen breath test. Apple juice was given at a dose of 15 ml/kg body weight, with a maximum of 375 ml. Fructose (0.6 g/kg) and sorbitol (0.06 g/kg), alone and in combination, were administered in amounts similar to their contents in apple juice (fructose as excess over glucose content). Apple juice malabsorption, as judged by a peak breath H2 excretion of > or = 20 ppm, was found in 11 children (65%) and 4 adults (33%). Of those malabsorbing apple juice, 7 of 11 children malabsorbed fructose, 1 of 11 sorbitol, and 4 of 11 the combination; the four adults absorbed all test solutions completely. We could not find an additive effect of sorbitol on breath H2 excretion after fructose ingestion. Peak breath H2 concentrations after apple juice ingestion (mean +/- SEM: 43 +/- 7 ppm) were higher than those with fructose (23 +/- 5 ppm; p < 0.05) or the fructose-sorbitol combination (20 +/- 5 ppm; p < 0.05). Fructose, and not sorbitol, is the sugar responsible for the increase in breath H2 after apple juice consumption and therefore for the diarrhea accompanying excessive apple juice consumption in toddlers.

Endomyocardial biopsy--its evaluation in cardiac disorders

Endomyocardial biopsies (EMBs) of 47 patients with various cardiac disorders were analysed. Clinically 26 patients were diagnosed as having dilated cardiomyopathy (DCM), 9 myocarditis, six restrictive heart disease and six as Duchenne muscular dystrophy. EMB showed normal histological picture in six cases of DCM and findings consistent with DCM in rest of the twenty cases. None of these biopsies showed evidence of myocarditis. Diagnosis of myocarditis could be confirmed on EMB only in three out of nine clinically diagnosed cases. Cases with restrictive heart disease showed normal biopsy in two, infarction in one, findings consistent with endomyocardial fibrosis in one and amyloidosis in two cases. EMB on six cases of Duchenne muscular dystrophy showed nonspecific histological changes. To conclude, in this series, cases of DCM did not show evidence of underlying myocarditis in endomyocardial biopsies.

Thymic histology in myasthenia gravis

Histological features of resected thymuses of 18 patients with myasthenia gravis were evaluated. Thymoma were seen in 16.6% of the patients. In the non-thymomatous group, thymic hyperplasia with follicle formation was seen in 33.3%, involuted thymus with occasional lymphoid follicle formation in 11.1%, thymitis with B cell infiltration in 16.6%, involuted thymus in 11.1% and normal thymus in 11.1% of patients. Immuno-histological staining for B and T lymphocytes delineated the group labelled as thymitis with B cell infiltration. Mast cell and eosinophils were frequently seen in thymuses with thymic hyperplasia with follicle formation and thymitis with B cell infiltration. Thymic hyperplasia with follicle formation was more frequent in young patients and these patients had better prognosis.

Human giardiasis: correlation of specific secretory IgA levels in duodenal fluid to the severity of disease and infestation by Giardia lamblia

Giardia lamblia specific secretory immunoglobulin A (sIgA) levels in the duodenal fluid of adult giardiasis cases are reported for the first time. The sIgA levels in the study group were found to be significantly higher (p less than 0.01) than in the 20 age- and sex-matched controls comprising cases classified as non-ulcerative dyspepsia who did nor reveal any G. lamblia in their stools and the duodenal fluid. An inverse relationship between the clinical severity of giardiasis and the level of sIgA in the duodenal fluid was noted. Cases with a higher trophozoite load in duodenal aspirate tended to be associated with envanescent G. lamblia-specific antibodies.

Solitary rectal ulcer syndrome

Solitary rectal ulcer syndrome (SRUS) clinically presents with rectal bleed. Twenty three cases of SRUS are described highlighting that it is a distinct clinicopathological entity which can be diagnosed in the presence of typical clinical features, sigmoidoscopic findings and histopathological appearance of mucosal biopsy.

Histological and immunological analysis of gastric and intestinal lymphomas

Immunophenotyping of 28 gastrointestinal non-Hodgkin's lymphomas was done using specific antibodies. Twenty six of these were successfully classified using this technique.

An unusual case of plasma cell granuloma involving lung and brain

A young male aged 20 years had resection of the upper lobe of right lung for plasma cell granuloma. Five years later he developed three lesions in the brain, one of which was resected. Brain lesion showed similar histopathological picture. A unique case of plasma cell granuloma involving more than one organ is reported.