Oxygen as a driving gas for nebulisers: safe or dangerous?

Changes in blood gas tensions occurring when 100% oxygen or air was used as the driving gas for nebulised salbutamol were studied in 23 patients with severe airways obstruction. The patients fell into three groups: nine had chronic bronchitis and emphysema with carbon dioxide retention, seven had emphysema and chronic bronchitis without carbon dioxide retention, and seven had severe asthma (no carbon dioxide retention). When oxygen was used as the driving gas patients who retained carbon dioxide showed a mean rise of 1.03 kPa (7.7 mm Hg) in their pressure of carbon dioxide (Pco2) after 15 minutes (p less than 0.001) but the Pco2 returned to baseline values within 20 minutes of stopping the nebuliser. The other two groups showed no rise in Pco2 with oxygen. When air was used as the driving gas none of the groups became significantly more hypoxic. Although it is safe to use oxygen as the driving gas for nebulisers in patients with obstructive airways disease with normal Pco2, caution should be exercised in those who already have carbon dioxide retention.

Toxic properties of the Mycoplasma arthritidis ISR-1 membrane

Isolated membranes of Mycoplasma arthritidis ISR-1 possess toxic properties for rats, mice and chicken embryos. Reactions are dose-dependent. By intravenous injection of 20 mg of membrane protein, a lethal toxicity syndrome resembling shock is induced in Sprague-Dawley rats of 100 g body weight. Mice of approximately 20-g body weight show the same syndrome by intravenous injection of 15 mg of membrane protein. The lethal toxicity for chicken embryos increases from 10 to 80% after injection of 0.3 to 1.5 mg of membrane protein. The LD50 in chicken embryos was found to be 0.5 mg membrane protein. After administration of 10-15 mg of membrane protein, rats showed an increase in temperature from 38 to 41 degrees C within 5 h. Because of the difficulty in measuring the temperature in mice, loss of body weight was taken as the criterion for toxicity. Body weight was reduced up to 16% within 1 day after intravenous injection of 500 micrograms of membrane protein per g of body weight. For sheep red blood cells, M. arthritidis ISR-1 membranes were haemolytic in concentrations of 4 mg of membrane protein and higher. Intradermal injection of 1 mg of membrane protein into guinea-pigs resulted in red swelling reactions measuring approximately 10 mm in diameter 10 h after injection. For foetal rat skin fibroblasts, M. arthritidis ISR-1 membranes were toxic in concentrations from 1 micrograms (3H-uridine incorporation), 10 micrograms (14C-leucine incorporation) and 100 micrograms (3H-thymidine incorporation) of membrane protein.

Capping of cholera toxin-ganglioside GM1 complexes on mouse lymphocytes is accompanied by co-capping of alpha-actinin

We used cholera toxin, which binds exclusively and with a high affinity to the ganglioside GM1, as a probe to investigate the distribution of this glycolipid on the surface of mouse lymphocytes. When lymphocytes are incubated with cholera toxin (or its B subunit) and then sequentially with horse anti-toxin and FITC-swine anti-horse Ig at 37 degrees C, the cholera toxin-ganglioside GM1 complex is redistributed to a cap at one pole of the cell. The capping of cholera toxin-GM1 complexes is slower than the capping of surface-Ig complexes, requires two antibodies, and is inhibited at high toxin concentrations. Cholera toxin-GM1, like surface-Ig capping, is an energy-dependent process and is inhibited by sodium azide, low temperatures, or cytochalasin B, but is unaffected by demecolcine. An affinity-purified antibody against alpha-actinin was used to examine the distribution of this cytoskeletal component during the capping process. 88% of the cells that had a surface Ig cap displayed a co-cap of alpha-actinin, and 57% of the cells that had a cholera toxin-GM1 cap displayed a co-cap of alpha-actinin. Time course studies revealed similar kinetics of external ligand cap formation and the formation of alpha-actinin co-caps. We conclude that capping of a cell-surface glycolipid is associated with a reorganization of the underlying cytoskeleton. The implications of such an association are discussed in the context of current models of the mechanism of capping.

Characterization of lactogen binding sites in choroid plexus

Prolactin binding sites have been demonstrated previously in rat choroid plexus using in vivo radioautography (Walsh et al. 1978). In the present study we have employed this procedure to characterize further the binding specificity of these sites. Following the injection of 125I-hGH or 125I-oPRL an intense radioautographic reaction was observed over the choroid plexus. The reaction was significantly reduced by coinjecting excess unlabeled hGH or oPRL but not bGH. The specific binding of 125I-oPRL to choroid plexus from rat, rabbit, sheep and pig was demonstrated by in vitro assays. Subsequently a survey of 125I-oPRL specific binding in a number of regions of pig brain indicated that the highest binding was in choroid plexus. A detailed study of the characteristics of 125I-oPRL binding to pig choroid plexus was undertaken. Specific binding increased with choroid plexus homogenate protein to a maximum of 30% (3.0 mg protein/tube). Binding was maximum at 4 degrees C by 30-40 h of incubation. During the incubation the integrity of 125I-oPRL in the incubation medium declined steadily to 50% after 20 h and 35-40% after 48 h. Radioactivity eluted from binding sites was fully intact as judged by rebinding to lactogen receptor-enriched membranes. Binding showed a broad pH optimum of 5.5-7.5. On cell fractionation of choroid plexus binding sites were enriched in microsomes. The binding of 125I-oPRL and 125I-hGH was inhibited in a dose-dependent manner by unlabeled lactogens and was of high affinity. hGH and oPRL were equipotent inhibitors of the binding of both radioligands whereas bGH and a variety of structurally unrelated peptides were non-inhibitory.

Characterization of the cholera toxin receptor on Balb/c 3T3 cells as a ganglioside similar to, or identical with, ganglioside GM1. No evidence for galactoproteins with receptor activity

Balb/c 3T3 cells contain a large number [(0.8-1.6) x 10(6)] of high-affinity (half-maximal binding at 0.2 nM) binding sites for cholera toxin that are resistant to proteolysis, but are quantitatively extracted with chloroform/methanol. The following evidence rigorously establishes that the receptor is a ganglioside similar to, or identical with, ganglioside GM1 by the galactose oxidase/NaB3H4 technique on intact cells was inhibited by cholera toxin. (2) Ganglioside GM1 was specifically adsorbed from Nonidet P40 extracts of both surface- (galactose oxidase/NaB3H4 technique) and metabolically ([1-14C]palmitate) labelled cells in the presence of cholera toxin, anti-toxin and Staphylococcus aureus. (3) Ganglioside GM1 was the only ganglioside labelled when total cellular gangliosides separated on silica-gel sheets were overlayed with 125I-labelled cholera toxin, although GM3 and GD1a were the major gangliosides present. In contrast no evidence for a galactoprotein with receptor activity was obtained. Cholera toxin did not protect the terminal galactose residues of cell-surface glycoproteins from labelling by the galactose oxidase/NaB3H4 technique. No toxin-binding proteins could be identified in Nonidet P40 extracts of [35S]-methionine-labelled cells by immunochemical means. After sodium dodecyl sulphate/polyacrylamide-gel electrophoresis none of the major cellular galactoproteins identified by overlaying gels with 125I-labelled ricin were able to bind 125I-labelled cholera toxin. It is concluded that the cholera toxin receptor on Balb/c 3T3 cells is exclusively ganglioside GM1 (or a related species), and that cholera toxin can therefore be used to probe the function and organisation of gangliosides in these cells as previously outlined [Critchley, Ansell, Perkins, Dilks & Ingram (1979) J. Supramol. Struct. 12, 273-291].

CT diagnosis of venous pseudotumors in the chest and abdomen

Appearances simulating neoplastic masses were found in five patients undergoing computed tomographic (CT) scanning of the chest and abdomen for a variety of indications. In each case the appearance was shown to be due to dilated collateral venous channels in association with portal hypertension or interruption of the inferior vena cava. The vascular origin of the masses was confirmed by CT scanning during intravenous bolus injection of contrast. Angiographic confirmation was obtained in three subjects. Enlarged collateral veins should be considered in the differential diagnosis of appearances suggesting mediastinal or abdominal lymphadenopathy at CT scanning.

Glenn shunt: long-term results and current role in congenital heart operations

Fifty cyanotic patients (aged 2 days to 22 years) underwent Glenn shunts for tricuspid atresia and other cyanotic heart defects. Thirteen of 15 operative deaths occurred in infants less than 4 months old, and only 1 death has occurred in the last 9 years. Results were poor in patients with Ebstein's anomaly, truncus arteriosus, transposition of the great vessels, and complex defects other than tricuspid atresia and univentricular heart. Of the 35 patients followed from 0.9 to 14.8 years, 12 were followed for more than 10 years. None of the 11 late deaths could be attributed to complications of the shunt. Minimal evidence of intrapulmonary shunting was found by angiography, pulmonary venous oximetry, or radioisotopic studies. Late deterioration due to venous collaterals and decreased flow to the opposite lung necessitated Blalock-Taussig shunts in 6 and Fontan procedures in 10. All survived the Fontan procedures with minimal morbidity. These data support the concept that Glenn shunts do not necessarily result in pulmonary abnormalities and may be indicated as a staged procedure in a few selected patients prior to a Fontan procedure.

Superior gluteal artery haemorrhage following pelvic features controlled by embolisation

Successful embolisation of active bleeding from the superior gluteal artery seen in two patients within the last 12 months is described. Both patients had extensive abdominal and pelvic injuries. One patient eventually died from renal failure and a perforated colon. The other patient is mobile and has been periodically seen in the out-patient department over the past nine months. In both instances, haemorrhage was at the sacrosciatic notch. Early angiography, in patients with extensive pelvic trauma and major blood requirements, with intent to embolise any identifiable bleeding source would appear to be the best initial manoeuvre to prevent exsanguination.

Secondary amenorrhoea due to autoimmune ovarian failure

A case of spontaneous premature menopause due to autoimmune ovarian failure is described. This report emphasises that this uncommon condition is important to diagnose because of its association with other autoimmune endocrine disorders including Addison's disease. In addition, in the present case, the marked increase in luteinizing hormone with relatively normal follicle stimulating hormone raises the possibility of a non-steroidal inhibitory feedback of follicle stimulating hormone.

Development of growth hormone receptors in rabbit and lamb liver after hypophysectomy

The prolactin receptors of rat liver are pituitary-dependent, and previous studies have shown that prolactin itself plays a role in inducing and maintaining their presence. This study tried to determine if hepatic growth hormone (GH) receptors are comparably dependent on the pituitary. Young 47-day and older 116-day old rabbits were either hypophysectomized (H) or sham-operated (S). Hypophysectomy completely arrested the growth of the older rabbits but only reduced it by 50 p. 100 in the young ones. After 21 days, the specific binding (sb) of 125I-labelled human GH (hGH) to liver membranes was measured in H and S animals. The sb of hGH in H rabbits compared to S animals (older, young) was 14.9 p. 100 in older H rabbits and 45.5 p. 100 in young H animals. Similar studies in lambs showed that the sb of hGH in H lambs (compared to S animals) was 23.9 p. 100. When some H lambs were treated with 1 mg/kg of oGH or bGH 3 times per week, the sb of hGH was significantly increased to 56.1 p. 100 of the S levels. All changes in sb reflected changes in receptor number, as shown by the dose response binding curves. This study demonstrates that hepatic GH receptors in both the rabbit and the lamb are pituitary-dependent. The level in rabbits is correlated with the growth rate. Since GH receptor levels were partially restored in GH-treated lambs, it is possible that GH plays a role in inducing its own receptors.

Experimental aminoglycoside nephrotoxicity

The nephrotoxicities of gentamicin and three other experimental aminoglycosides were compared at a single 60 mg. per kilogram per day dose in rats. Renal function, lysosomal enzymuria, and antibiotic concentrations in plasma, urine, and renal tissue were measured at regular intervals throughout the course of treatment. Kidney tissue was examined by light and electron microscopy in animals killed at intervals throughout the period of antibiotic administration. Proteinuria and enzymuria were early indicators of nephron dysfunction, whereas endogenous creatinine clearance declined later in the course of treatment. All animals were killed 24 hours after a previous antibiotic injection and displayed sustained renal tissue antibiotic concentrations which were 5 to 10 times higher than those in serum or urine. When assayed separately, renal cortical tissue had a fivefold greater antibiotic concentration than renal medulla. Light microscopy displayed necrosis of the pars convoluta of the proximal tubule. Electron microscopy revealed appearance of cytosegrosomes with myeloid bodies. It is possible that impaired cytoplasmic degradation of sequestered organelle membranes, resulting from aminoglycoside accumulation, is responsible for the myeloid body formation and subsequent tubular necrosis.

Enzymuria in gentamicin-induced kidney damage

To assess their potential value as early indicators of gentamicin-induced kidney damage, lysosomal hydrolases were measured in the 24-h urines of rats receiving 30 or 60 mg of gentamicin per kg per day for 15 days. Proteinuria, urine osmolality, blood urea nitrogen, and creatinine clearance were also measured. Kidney tissue was examined by both light and electron microscopy. Beta-galactosidase, beta-n-acetyl-hexosaminidase, and alpha-fucosidase were sensitive indicators and were significantly elevated above control values by day 3 at both doses (P < 0.01). Proteinuria, urine osmolality, and tests reflecting glomerular filtration rate were later indicators of nephron damage. Changes by light microscopy were detected on day 5. Necrosis was most prominent in the proximal convoluted tubules on day 10. Electron microscopy revealed numerous cytosomes with myeloid bodies within the proximal tubular epithelium on day 5. Lysosomal enzymuria appears to be an early manifestation of gentamicin nephrotoxicity and may possibly be related to the lysosomal abnormalities seen on electron microscopy.