Aluminium bone disease in patients receiving plasma exchange with contaminated albumin.

Aluminium balance studies were carried out on eight patients with various immunological disorders who were receiving plasma exchange with albumin solutions known to be contaminated with aluminium. Four patients with impaired renal function (creatinine clearance less than 50 ml/min) retained between 60% and 74% of the aluminium infused during a single plasma exchange. Transiliac bone biopsy specimens from three patients in this group had a high content of aluminium and showed histological evidence of current or previous bone disease related to aluminium. Two of these patients suffered intermittent bone pain. The main route of excretion of injected aluminium was in urine, only a small proportion of the total input being removed in the "plasma bag" during plasma exchange. The extent of aluminium retention and bone deposition was not reflected by the plasma aluminium concentration before or after plasma exchange. Treatment of five patients with intravenous desferrioxamine increased the plasma aluminium concentration and urinary output of aluminium in those with evidence of aluminium retention. These studies show that patients with poor renal function receiving treatment with albumin contaminated with aluminium retain the metal and deposit it in bone, where it may eventually cause aluminium bone disease. Plasma exchange should be used with caution in patients with renal impairment.     

Mucosal epithelial cells and Langerhans cells are targets for infection by the immunosuppressive type D retrovirus simian AIDS retrovirus serotype 1

Simian acquired immune deficiency syndrome (SAIDS) caused by the type D retrovirus SRV-1 results in opportunistic infections and a spectrum of oral lesions similar to those seen in humans with AIDS. To better understand the pathogenesis of these oral lesions we have retrospectively examined the oral mucosa from ten rhesus monkeys that died with SAIDS and prospectively examined the oral mucosa of ten additional animals inoculated with SRV-1 to determine at what time, and in what cells SRV-1 infection of the oral mucosa occurs. Using single and double label immunohistologic techniques, and electron microscopy we detected SRV-1 in clusters of oral epithelial cells and rare Langerhans cells as early as 1 month postinoculation.     

Mitochondrial DNA in the Bark Weevils: Size, Structure and Heteroplasmy

Mitochondrial DNA of higher animals has been described as an example of extreme efficiency in genome structure and function. Where exceptionally large size molecules have been found (greater than 20 kb), most have occurred as rare variants within a species, suggesting that these variants arise infrequently and do not persist for long periods in evolutionary time. In contrast, all individuals of at least three species of bark weevil (Curculionidae: Pissodes) possess a mitochondrial genome of unusually large size (30-36 kb). The molecule owes its large size to a dramatically enlarged A + T-rich region (9-13 kb). Gene content and order outside of this region appear to be identical to that found in Drosophila. A series of 0.8-2.0-kb repeated sequences occur adjacent to the large A + T rich region and have perhaps played a role in the generation of the large size as well as an unprecedented frequency of size variant heteroplasmy. Every weevil sampled in all three species (n = 219) exhibits anywhere from two to five distinct size classes of mtDNA. The persistence of this large amount of size polymorphism through two speciation events combined with the abundant size variation within individuals suggests that these molecules may not be subject to strong selection for small overall size and efficiency of replication. This pattern of variation contrasts strongly with the conservation of gene content and arrangement in the coding region of the molecule.     

Patterns of energy storage in Pseudoboeckella poppei (Crustacea,copepoda) from two contrasting lakes on Signy Island,Antarctica

The copepod Pseudoboeckella poppei (Daday) (Calanoida, Centropagidae) was sampled from Sombre and Heywood Lakes on Signy Island, Antarctica (60° S, 45° W) between January 1984 and March 1985. Sombre Lake is clear and oligotrophic with little phytoplankton and a bottom sediment low in organic content. By contrast Heywood Lake is turbid and mesotrophic; a substantial phytoplankton develops in summer and the bottom sediments are comparatively rich in organics. Both lakes freeze over for much of the year, forcing the copepods to adopt a benthic feeding strategy over winter. Adult Pseudoboeckella feed on phytoplankton when this is available, but also on detritus, diatoms and short algal filaments stirred up from the sediment. In Heywood Lake, male copepods show a smooth seasonal trend in lipid content with lipid being synthesised in early summer and utilised in late summer and winter. The summer increase in lipid content is associated with an increase in dry weight. Female lipid contents show evidence of two peaks of egg production. In Sombre Lake both male and female copepods increase in size during summer and show a wider range of lipid contents than in Heywood Lake; it is likely that this is due to the poorer winter feeding conditions which necessitate the synthesis of a much larger store of reserves during the summer. In contrast to marine calanoid copepods, lipid stores are exclusively triacylglycerol with no trace of wax ester.     

Complications of Gastroesophageal Reflux

An edited summary of an Interdepartmental Conference arranged by the Department of Medicine of the UCLA School of Medicine, Los Angeles. The Director of Conferences is William M. Pardridge, MD, Professor of Medicine.Several specialists have recently recognized that gastrointestinal reflux causes complications resulting in significant disease. It causes discomfort, indigestion, esophagitis, Barrett''s esophagus, and carcinoma of the esophagus. Pediatricians attribute many early pulmonary problems, and even some sudden deaths in infants, to the reflux of gastric contents. Otolaryngologists now recognize that many cases of nonbacterial, nonspecific pharyngitis and laryngitis are due to the reflux of gastrc acid secretions. Contact granuloma and cancer of the larynx may, in some instances, be secondary to nocturnal reflux. Thoracic surgeons and pulmonologists believe chronic tracheobronchitis and some cases of pulmonary disease are attributable to recurrent bathing of the respiratory epithelium by aspirated gastric contents. An awareness of the many complications of gastrointestinal reflux should lead to a multidisciplined attack on the factors responsible for these diseases.     

The marginal regions of thylakoid membranes: A partial characterization by polyoxyethylene sorbitan monolaurate (Tween 20) solubilization of spinach thylakoids

The detergent Tween-20 solubilized preferentially portions of the marginal regions of Spinacea oleracea L. thylakoid membranes and, thus, opened the inside of the grana to the external media. Differential centrifugation. following Tween-20 solubilization. enabled separate fractions of grana and stromal-exposed membranes to be isolated. Analysis of Tween-20 solubilized material, after pelleting all membrane material by centrifugation at 100 000 g, revealed polypeptides associated with the coupling factor (CF₁) particles, cytochrome b₆/f and photosystem II complexes, suggesting that the marginal membranes contain these proteins. Concomitantly, the 100 000 g pellet was depleted in cytochrome b₆/f and P700, determined spectroscopically, Thus. our results reveal the margin to be a distinct membrane region, which does not contain the light-harvesting centers of photosystem II (LHC II). The implication of these results, in terms of the energetic interaction of components of granal and stromalexposed membrane regions, is discussed.