Canine antibody response to Blastomyces dermatitidis WI-1 antigen.

OBJECTIVE: To assess whether dogs with blastomycosis produce antibodies against the WI-1 and A-antigens of Blastomyces dermatitidis and whether the antibodies are useful in serodiagnosis. SAMPLE POPULATION: 359 serum samples obtained from 245 dogs. PROCEDURE: 233 samples from 122 dogs with blastomycosis, and 1 sample each from 24 dogs with suspected blastomycosis, 51 control dogs without infection, and 48 healthy dogs from an enzootic region were obtained. Antibodies against WI-1 antigen were detected by radioimmunoassay (RIA). Serum samples were tested in parallel for antibodies against the A-antigen of B dermatitidis by commercial agar-gel immunodiffusion (AGID) in a reference laboratory. RESULTS: Antibodies were detected in 92% of infected dogs by RIA and in 41 % by AGID. For 29 serum samples that were obtained 11 to 1,545 days after diagnosis, antibodies were detected in 92% of samples by RIA and 7% by AGID. For 93 serial serum samples from 29 dogs with blastomycosis, the mean anti-WI-1 titer was 1:18,761 at the time of diagnosis, and decreased to a mean of 1:1,338 by 210 days after treatment was initiated. Of 24 dogs with suspected infection, antibodies were detected in 67% by RIA and 33% by AGID. Control dogs without blastomycosis had no detectable antibodies in either assay. Thus, sensitivity was 92% for RIA and 41 % for AGID, and specificity was 100% for both tests. CONCLUSIONS AND CLINICAL RELEVANCE: Anti-WI-1 antibodies are readily detected by RIA in dogs with blastomycosis. Titers become high, decline during treatment, and persist for months. Anti-A antibodies are sometimes detected with AGID, but these decrease quickly.

Response to drugs and diet in a compound heterozygote for familial hypercholesterolaemia.

A boy with a total plasma cholesterol concentration of 20.9 mmol/l which fell significantly with a low fat diet, cholestyramine and simvastatin, was shown to have two different mutations in the low density lipoprotein receptor gene, demonstrating that some patients with homozygous familial hypercholesterolaemia show a good lipid lowering response to treatment.

Nodular transformation of the liver associated with portal and pulmonary arterial hypertension.

A case of multiple focal nodular hyperplasia (FNH) of the liver associated with noncirrhotic portal hypertension and later complicated by pulmonary arterial hypertension leading to death from right heart failure is reported. In retrospect, the portal hypertension diagnosed in early life was most likely due to a congenital hypoplasia of portal vein branches and multiple FNH, a hyperplastic response of the liver parenchyma in association with anomalies of hepatic arterial branches as found within the lesions. This case may represent a form of multiple FNH syndrome restricted to the liver, because neither extrahepatic vascular malformation nor brain tumor was identified at autopsy. The FNH lesions had considerably expanded over the years, and the severe sinusoidal congestion due to chronic right-sided heart failure with subsequent prolonged parenchymal exposure to blood-borne hepatotrophic factors is a likely explanation for both the massive enlargement of FNH lesions and the nodular regenerative hyperplasia observed in the intervening parenchyma.

Non-invasive detection of endothelial dysfunction in children and adults at risk of atherosclerosis.

Endothelial dysfunction is an early event in experimental studies of atherogenesis, preceding formation of plaques. We have devised a non-invasive method for testing endothelial function, to find out whether abnormalities are present in symptom-free children and young adults at high risk of atherosclerosis. With high-resolution ultrasound, we measured the diameter of the superficial femoral and brachial arteries at rest, during reactive hyperaemia (with increased flow causing endothelium-dependent dilatation), and after sublingual glyceryl trinitrate (GTN; causing endothelium-independent dilatation) in 100 subjects--50 controls without vascular risk factors (aged 8-57 years), 20 cigarette smokers (aged 17-62 years), 10 children with familial hypercholesterolaemia (FH; aged 8-16 years), and 20 patients with established coronary artery disease (CAD). Adequate scans were obtained in all but 6 cases. Flow-mediated dilatation was observed in arteries from all control subjects. Dilatation was inversely related to baseline vessel diameter (r = -0.81, p < 0.0001); in arteries of 6.0 mm or less, mean dilatation was 10 (SE 2)%. In smokers, FH children, and adults with CAD, flow-mediated dilatation was much reduced or absent (p < 0.001 for comparison with each relevant control group). Dilatation in response to GTN was present in all groups. Endothelial dysfunction is present in children and adults with risk factors for atherosclerosis, such as smoking and hypercholesterolaemia, before anatomical evidence of plaque formation in the arteries studied. This may be an important early event in atherogenesis.

Cholesterol: should we screen all children or change the diet of all children.

Hypercholesterolaemia is a major risk factor for coronary heart disease and may present during childhood. Dietary measures can reduce plasma cholesterol and may thus delay or prevent the development of the atherosclerotic process. Although plasma cholesterol concentrations measured during childhood track into adult life with a correlation coefficient of about 0.6 this in itself is insufficient to justify total population screening of children especially as the mechanisms for management and follow-up and their social, psychological and economic implications have not been adequately evaluated. Targeted screening of children in families with the genetic disorder of familial hypercholesterolaemia, where the risk of premature coronary heart disease is very high, should, however, be undertaken even though such screening may only identify half of all affected children. Dietary change designed to lower plasma cholesterol can be applied to the whole population including children over the age of 2 years, does not require pre-determination of plasma cholesterol, and is to be recommended. The effects of such change on the growth and health of children should be monitored.

In vivo and in vitro characterization of mesothelial lipid inclusions.

The nature of intracytoplasmic lipid inclusions found in cultured rabbit and rat peritoneal mesothelial cells was examined by ultrastructural and biochemical techniques. Transmission electron microscopy also demonstrated extracellular release of these lipid bodies. Differential fixation with tannic acid revealed 2 types of inclusions, lamellated (lamellar bodies) and nonlamellated (homogeneous). The lamellar bodies were found near or in the Golgi apparatus and on the cell surface where occasionally they were observed in exocytotic pouches. The homogeneous inclusions were the predominant species being found primarily intracellularly. Lipid bodies obtained from the culture media over the cells displayed on electron microscopy the same morphological characteristics as those seen intracellularly. Exposure of confluent cultures of mesothelial cells to the vital lipid stain Nile Red caused the appearance of intensely fluorescent droplets in or on the cells at wave lengths consistent with staining for phosphatidylcholine-rich vesicles. Incubation of the cells with (14C)-choline and subsequent analysis of phospholipid formation revealed high rates of (14C)-phosphatidylcholine addition to both intra- and extracellular lipid pools. Taken together, mesothelial cells exhibit lipid bodies similar in ultrastructure to the surfactant containing organelles of Type II pneumocytes.

Abetalipoproteinemia with an ApoB-100-lipoprotein(a) glycoprotein complex in plasma. Indication for an assembly defect.

Patients with autosomal recessive abetalipoproteinemia (ABL) lack in their plasma all lipoproteins containing apolipoprotein (apo)B-100 or B-48. Previous studies have suggested that this is due to the complete absence of apoB. We have investigated whether such patients (n = 10) are able to secrete the lipoprotein(a) (Lp(a] glycoprotein (apo(a] which, in normal plasma, exists as a complex with low density lipoproteins containing apoB-100 (Lp(a) lipoprotein). All 10 patients had reduced but detectable apo(a) levels in plasma (mean, 0.49 mg/dl; range, 0.2-2.03 mg/dl) but no Lp(a) lipoprotein. However, we also detected small amounts (0.2-2.8 mg/dl) of apoB in all patients with ABL. The apoB in the ABL patients had the size of apoB-100 and occurred as a lipid-poor complex with the Lp(a) glycoprotein in a fraction of density 1.22 g/ml. This material may represent partially assembled Lp(a) lipoprotein. There was also uncomplexed apo(a) and apoB-100 in the ABL plasma. The distribution and relative concentration of both proteins in the density fraction greater than 1.06 g/ml varied among patients. The data suggest that in ABL, the assembly of apoB-containing lipoproteins is defective and that apoB-100 may be secreted without its full lipid complement when complexed with apo(a).

Categorization of ultrastructural changes in peritoneal mesothelium, stroma and blood vessels in uremia and CAPD patients.

This paper presents an interim report on the findings of the International Peritoneal Biopsy Registry (IPBR). The registry was set up for the collection and morphological examination of specimens of peritoneal tissue obtained at surgical implantation or removal of the catheter before, during or after treatment with continuous ambulatory peritoneal dialysis (CAPD). The key objective of the Registry is the accumulation of information on the effect of peritoneal dialysis, peritonitis and any other complication of the therapy, on the structural integrity of peritoneal mesothelium, stroma and blood vessels.

Nephrocalcinosis in Shwachman's syndrome.

Nephrocalcinosis has been reported only infrequently in Shwachman's syndrome. We describe a case in which nephrocalcinosis occurred and speculate that this may be due to increased urinary oxalate excretion.

Mesothelium secretes lamellar bodies in a similar manner to type II pneumocyte secretion of surfactant.

In the early 1970s it was found that a specific lipid-fixing technique of tissue preparation for electron microscopy (tannic acid-glutaraldehyde) preserved and thus unmasked distinctive inclusions in Type II pneumocytes which were called lamellar bodies. This discovery was the first crucial step in demonstrating that lamellar bodies were the storage granules from which alveolar surfactant was secreted. In a previous study a comparison between mesothelium and Type II pneumocytes showed close ultrastructural similarities. In the present investigation of normal peritoneal tissue from man, monkey, rabbit and mouse, following primary tannic acid-glutaraldehyde fixation and modified embedding procedures similar to those used for lung, examination by transmission electron microscopy demonstrated in all mesothelial cells examined, characteristic lamellar structures similar to those described in Type II pneumocytes. Exocytotic extrusion of lamellar bodies from the apical portion of the mesothelial cell, and the presence of lamellar bodies on the cell surface in a manner identical to that found in Type II pneumocytes was also observed. These findings provide compelling evidence that a process of specialized biosynthesis and secretion of phospholipids similar to that established for Type II pneumocytes also occurs in mesothelial cells.

Genetic evidence from two families that the apolipoprotein B gene is not involved in abetalipoproteinemia.

Abetalipoproteinemia (ABL) is a recessive disorder in which affected individuals have extremely low or undetectable levels of serum apo B-containing lipoproteins. Using restriction fragment length polymorphisms, we have studied two families, each with two children with classical ABL born of normal parents. In each of these families, the two affected children have inherited different apo B alleles from at least one parent, whereas the siblings would be anticipated to share common alleles if this disorder were due to an apo B gene mutation. This linkage study shows that in these families, the apo B gene is discordant with ABL and therefore the disorder is caused by a defect in another gene, which is important for the normal synthesis or secretion of apo B-containing lipoproteins from both the liver and intestine.

Substrate specificity of plasma lecithin: cholesterol acyltransferase in abetalipoproteinemia.

The lecithin: cholesterol acyltransferase (LCAT) activity of lipoprotein-depleted plasma from a patient with abetalipoproteinemia has been assayed in a modified Glomset-Wright incubation system with three different normal lipoprotein substrates consisting of an authentic mixture of very low (VLDL), low (LDL) and high (HDL) density lipoproteins for the assay of total LCAT activity, HDL to assay alpha-LCAT activity and combined VLDL and LDL to assay beta-LCAT activity, respectively. Although reduced to about half the normal control values, both alpha- and beta-LCAT activities were present in the patient's plasma. It has been shown earlier that secretion of LCAT is linked to that of VLDL, but since patients with abetalipoproteinemia cannot form either chylomicrons or VLDL, our results suggest that a secretion of these triglyceride-rich lipoproteins do not seem to be a prerequisite for a basal secretion of beta-LCAT.

Timing of strict diet in relation to fetal damage in maternal phenylketonuria. An international collaborative study by the MRC/DHSS Phenylketonuria Register.

64 infants born to women with phenylketonuria (PKU) were grouped according to the mother's dietary treatment in pregnancy. 17 infants, whose mothers were receiving a strict low phenylalanine diet and had blood phenylalanine concentrations below 600 mumol/l at the time of conception, had normal birthweights and head circumferences and no malformations. In the 29 infants whose mothers were receiving either a relaxed diet or a normal diet at conception but who started a strict diet at some time during pregnancy, birthweights and head circumferences were below those in healthy infants and there was an excess of malformations; the findings closely resembled those for the 18 infants whose mothers received no treatment during pregnancy. The birthweights and head circumferences of the 64 infants were inversely related to the maternal phenylalanine concentrations around the time of conception. Only a strict diet started before conception is likely to prevent fetal damage.

Plasma lipoprotein disorders in childhood.

Disturbances of the plasma lipoproteins occur as a secondary manifestation in many diseases and usually resolve with treatment of the underlying condition. Of the inherited primary disorders familial hypercholesterolaemia is the most common and important, carries a high risk for premature coronary heart disease in adults, and should be diagnosed and treated in childhood.