Response to therapy of a type III hyperlipoproteinemic subject with the rare apolipoprotein E1 (Gly127 → Asp,Arg158 → Cys) variant

Summary In a preceding paper, we described the molecular biological defects in a patient with a severe form of the familial lipoprotein disorder type III hyperlipoproteinemia (HLP) and an unusual apolipoprotein (apo) El phenotype and 1/null genotype. The index case was a 60-year-old white male of German ancestry who suffered from a myocardial infarction at age 50 years. He had distinctly elevated levels of plasma lipids (triglycerides 551 mg/dl and cholesterol 747 mg/dl, respectively) and typical clinical signs of this inborn error of lipoprotein metabolism. His mutant apo E1 was shown to be identical to a rare (already described) apo E1 (Gly₁₂₇Asp, Arg₁₅₈Cys) variant. A second independent defect at the molecular level was a nucleotide deletion of a guanosine (G) in the codon for amino acid 31 of the proband's apo 3 allele. This single base deletion (not described before) changed his apo 3 allele to a nonfunctional null allele devoid of a stable gene product. Here we describe the response to combined dietary and medical treatment of the patient with this unusual form of type III HLP. His response to therapy was excellent, similar to patients with classical type III HLP and homozygosity for apo E2. However, the correct diagnosis of this familial lipoprotein disorder seems to be necessary, even in patients without the expected apo E2/2 phenotype, in terms of the prompt and beneficial response to therapeutic interventions.Abbreviations Apo Apolipoprotein - Chol cholesterol - HDL high density lipoproteins - HDL-C HDL-cholesterol - HLP hyperlipoproteinemia - IDL intermediate density lipoproteins - IEF isoelectric focusing - LDL low density lipoproteins - LDL-C LDL-cholesterol - TG triglycerides - VLDL very low density lipoproteins - VLDL-C VLDL-cholesterol Dedicated to Prof. Dr. G. Schettler on the occasion of his 75th birthday on April 13, 1992     

Clinical features of type III hyperlipoproteinemia: analysis of 64 patients

Summary The clinical and biochemical characteristics of type III hyperlipoproteinemia are described in 64 patients (35 males and 29 females). Homozygosity for apolipoprotein E2, the presence of an abnormally cholesterol-rich very low density lipoprotein fraction (-VLDL) and an elevated ratio of very low density lipoprotein cholesterol to plasma triglycerides (>0.3; normal ratio about 0.2) were the basis for the diagnosis. Mean serum cholesterol and triglyceride concentrations at the first visit in the clinic were 426 ± 221 and 719 ±996 mg/dl, respectively. The mean age at diagnosis of the disorder was 49 years in males and 53 years in females. There was a high prevalence of obesity (72%), xanthomas (42%), and atherosclerosis (39%), especially peripheral vascular disease (31%). Early and correct diagnosis of this familial lipoprotein disorder seems necessary because of the prompt and beneficial response to therapeutic interventions.Abbreviations Apo apolipoprotein - BMI body mass index - CAD coronary artery disease - HDL high-density lipoproteins - HLP hyperlipoproteinemia - HMG CoA 3-hydroxy-3-methylglutaryl coenzyme A - LDL low-density lipoproteins - Lp(a) lipoprotein (a) - PVD peripheral vascular disease - TG triglycerides - VLDL very low density lipoproteins     

Mapping thyrotropin β subunit gene in man and mouse

Thyrotropin (TSH) is composed of two subunits: and . Previously, we have mapped the TSH gene to human chromosome 6 and mouse chromosome 4. In this study we have located the human TSH gene on chromosome 1 and the mouse TSH gene to chromosome 3. These data suggest that the TSH gene lies in a conserved linkage group with the genes for amylase 1 and 2, nerve growth factor, and the protooncogene Nras.     

Lipid changes in the nephrotic syndrome: New insights into pathomechanisms and treatment

Summary The abnormalities of lipid metabolism in nephrotic syndrome consist in an increase in total and low-density lipoprotein (LDL) cholesterol, apoliproteins B (ApoB), C-II and C-III, associated in patients with heavier or marked hypoalbuminemia with an increase in triglycerides and very low-density lipoprotein (VLDL) cholesterol, while the high-density lipoproteins (HDL) are distributed abnormally (increased HDL3 fraction and decreased HDL2 fraction) and the Apo A-I to Apo B ratio is reduced. Both increased hepatic lipoprotein synthesis and reduced removal capacity contribute to this hyperlipidemia. Proteinuria may lead to the lipoprotein abnormalities through stimulation of VLDL synthesis by the liver induced by hypoalbuminemia, although it has been more recently suggested that urinary protein loss is associated with the urinary loss of some important cofactor for the regulation of lipid synthesis or catabolism.Treatment of lipid abnormalities in patients with long-lasting heavy proteinuria is mandatory, because they may cause or contribute to accelerated atherosclerosis, but also because they appear to accelerate progression of renal disease by favouring mesangial sclerosis. Four groups of lipidlowering drugs have been tested: 1) bile acid-binding resins; 2) fibric acid; 3) probucol; 4) inhibitors of HMG CoA reductase. The drugs of the last group appear to be effective and safe in short-term experiments, but long-term studies are necessary to confirm their validity. A dietary approach, consisting in a strictly vegetarian soy diet, very rich in polyand monounsaturates fatty acids, has been recently tested by the author, with very promising results.Abbreviations LDL low density lipoproteins - VLDL very low density lipoproteins - HDL high density lipoproteins - Apo Apolipoprotein - LCAT Lecithin cholesterol acyltransferase - HMGCoA Hydroxymethylglutaryl coenzyme A Preprint of a lecture to be read at the 22nd Congress of the Gesellschaft für Nephrologie, Heidelberg, September 15–18, 1991 (Editor: Prof. Dr. E. Ritz, Heidelberg)     

Effects of sleep deprivation on the activity of selected metabolic enzymes in skeletal muscle

Summary The present study gives the results of a comparison of the recorded and true tibia-calcaneal angles in 17 normal subjects and in 14 patients with abnormally hypoextensible non contracting triceps. 1. For a minimal passive torque, the difference between true and recorded angles varied considerably from one individual to another. The means and ranges for the two groups were respectively: –8 (+7, –21) and –7 (+5, –20). 2. When the passive torque increased as a result of slow passive lengthening of the muscle, the true curve was steeper than the recorded one, owing to differences between the two angle measurements. For each of the two groups the differences in means and ranges were respectively: 6 (0, +13.5) and 8 (3, 12). 3. Subjects made isometric voluntary contractions of the triceps surae at fixed angles which corresponded to step by step muscle lengthening. The resulting true curve was much steeper than the recorded curve. The differences in means and ranges were: 7 (1.5, +15) in children of the two groups and respectively 3 (0, +9) and 12 (10, 14) in adults of the two groups. The present results show that this methodology was the only reliable way of correctly obtaining passive and active torque-angle curves, measuring differences between subjects, appreciating the effects of treatments and these by ascertaining whether or not trophic muscle regulation was defective.     

On the terms “reticulosis” and “reticulum cell sarcoma” with regard to the modern concept of the monocyte macrophage system

Summary The terms reticulosis and reticulum cell sarcoma (= malignant lymphoma, histiocytic type) are discussed regarding the modern concept of the monocyte macrophage system which today has replaced the ancient theory of the reticuloendothelial system. The monocyte macrophage system is not independent, but closely related to the myeloid system. Thus, a third blood forming system as was believed in the case of RES does not exist. Phagocytic reticulum cells of the various hematopoietic organs are highly activated monocyte-derived macrophages. All those conditions formerly termed reticuloses have been found to belong either to the myeloid or to the lymphatic system. Considering the reticulum cell sarcomas or malignant histiocytic lymphomas, most of them seem to be of lymphatic rather than of macrophage origin, representing highgrade malignant lymphomas, possibly immunoblastic sarcomas. No relationship between these tumours and the monocyte macrophage system has been established, so far. Therefore, the terms reticulosis and reticulum cell sarcoma should be no longer used in order to avoid confusion, in order to stimulate sufficient diagnostic efforts which will really clarify such cases, and in order to give full credit to modern results of hematopathology.     

Resistance toTrypanosoma cruzi infection in relation to the timing of IgG humoral response

The Biozzi high (BH) and low (BL) responder mice (Selection III) differeed in their susceptibility toTrypanosoma cruzi. The BH strain responded quickly to the infection, similar to the reaction of (CBA×C57B1/10)F₁ mice but in contrast to the susceptible BL strain. We suggest that the IgG response mounted by the host during the prepatent period of the infection is crucial to the outcome of the infection.     

Reiterated sequences of herpes simplex virus type 1 (HSV-1) genome can serve as physical markers for the differentiation of HSV-1 strains

Summary The stability of regions containing tandemly reiterated sequences in the S component of the herpes simplex virus type 1 (HSV-1) genome was determined, by comparing restriction fragments of the regions among sets of HSV-1 isolates derived from a single source. The 6 reiterations examined were grouped into three. Reiteration VII (within protein coding regions of genes US10 and US11) and reiteration IV (within introns of genes US1 and US12) were stable between the isolates (group 1). Regions containing one of four other reiterations were detected as a set of ladder-like fragments. Reiteration II (between a sequence and IE175 gene) and reiteration VI (within an intergenic region on the 3 side of the 3 co-terminal family of genes US10, US11, and US12) (group 3) were more unstable than reiteration I (within a sequence) and reiteration III (between a sequence and IE175 gene) (group 2). The mode of fluctuation of the reiterations observed within a set of HSV-1 strains isolated from an individual was similar to that observed between HSV-1 single-plaque clones separated in cultured cells. These reiterations, except for group 3, can serve as sensitive and convenient markers for differentiating HSV-1 strains.     

In situ expression of β1, β3 and β4 integrin subunits in non-neoplastic endothelium and vascular tumours

Endothelial cells play an important role in adhesive interactions between circulating cells and extracellular matrix proteins. In vitro studies have shown that many of these processes are mediated by a superfamily of heterodimeric transmembrane glycoproteins called integrins. The distribution patterns of 1, 3 and 4 integrin subunits in endothelial cells (EC) in situ were examined immunohistochemically on serial forzen sections of a wide range of non-neoplastic tissues and of vascular tumours, both benign and malignant. Expression of the 1 subunit was a constitutive feature of EC. Among the 1-associated subunits, 5 and 6 were broadly distributed in EC, irrespective of vessel size and microenvironment. The 3 subunit displayed intermediate levels of expression with a slight preference for small vessel EC. Presence of 1 was confined to EC of capillaries and venules/small veins. Expression of 2 in EC was inconsistent. With rare exceptions, the 4 chain was absent in EC. The 3 and v subunits were expressed in most EC, though not always concomitantly. In contrast to the 1 chain, however, these integrin subunits were absent in EC of glomerular capillaries and were expressed variably in sinusoidal EC. The 4 chain was evenly present in the great majority of EC, except for those of large vessels. In vascular tumours, the patterns of 1 and 1 to 6 subunit expression generally corresponded to those found in their non-neoplastic counterparts. Expression of 3, v and 4 chains, however, decreased in neoplasia, especially in angiosarcomas. These data show that EC dispose of broad and at the same time differential repertoires of integrin subunits that presumably reflect vessel-type associated functional differences among these cells. In vascular tumours, the orthologous distribution patterns of 1 and 1 to 6 chains are conserved in most instances while the amounts of 3, v and 4 subunits expressed in EC tend to decrease in the course of malignant transformation.Dedicated to Prof. Dr. med. Dres. h.c. Wilhelm Doerr on the occasion of his 80th birthday     

Familial disorders of plasma apolipoproteins

Summary Numerous molecular variants of the protein moiety of human circulating lipoproteins (apolipoproteins or apoproteins) have been described in recent years. Molccular alterations of apolipoproteins may lead to an impaired lipid binding and/or to an accelerated or delayed lipoprotein catabolism. Many variants, particularly those of the E apoprotein system, are associated with premature atherosclerosis. In the case of the Apo AI variants, the concomitant deficiency of Apo AI and Apo CIII leads to severe clinical atherosclerosis. Conversely, molecular variants of Apo AI (several of which come from FRG, i.e. AI-Marburg, -Giessen, -Münster) do not go together with significant clinical abnormalities. The case is different for Tangier disease, characterized by the complete absence of high density lipoproteins, where a dramatic tissue lipid deposition may occur. One molecular variant, Apo AI-Milano, while leading to a significant reduction of HDL, does not seem to be associated with clinical atherosclerosis, but rather with a protection from the disease. The presence of major apolipoprotein abnormalities in familial groups of variable size, provides a molecular explanation for some significant alterations of lipid metabolism. Moreover, it offers, to clinical and basic studies, a useful model for the understanding of the function and metabolism of human apolipoproteins.Abbreviations ABL abetalipoproteinemia - Apo apoprotein - CAD coronary artery disease - HBL hypobetalipoproteinemia - HDL high density lipoproteins - HL hepatic lipase - IEF isoelectric focusing - LCAT lecithin-cholesterol acyltransferase - LDL low density lipoproteins - LPL lipoprotein lipase - Proapo proapoprotein - VLDL very low density lipoproteins     

A phylogenetic and evolutionary justification for three genera of Geminiviridae

Summary Gene-by-gene phylogenetic analyses of all of the viruses for which sequences are known, as well as analysis of the coding capacities, clearly demonstrated that there are two major groups of viruses in the taxonomic familyGeminiviridae. These are of the Subgroup I type, with one genomic component, which mainly infect monocots and are leafhopper-transmitted; and of the Subgroup III type, with one or two genomic components, which infect dicots and are whitefly-transmitted. The existence of New World and Old World clusters of Subgroup III viruses was confirmed, as well as the possession by the latter of an AV1 ORF not present in New World viruses. A third minor generic group is defined by viruses of the Subgroup II type, which have a single genomic component, infect dicots, and are leafhopper-transmitted. The latter group appear to be the result of an ancient recombination event between a Subgroup III-like and a Subgroup I-like virus. The question of whether one- and two-component Subgroup III viruses should be in the same taxon appears hard to resolve: the only distinguishing feature of the one-component Subgroup III viruses is that they apparently have no second component, as gene-for-gene comparisons of the A components of the viruses with other Subgroup III viruses place them within a larger Old World group of viruses, most of which are two component. The possibility exists that these viruses may either have independently lost their B components, or possess a B component that has simply not yet been found. Possible nomenclatural changes to accommodate viruses with the same name which are not closely related to one another, and possible evolutionary scenarios to account for the observed familial, generic and specific diversity of geminiviruses, are discussed.     

Disturbance of delayed match-to-sample in macaques by tetanization of anterior commissure versus limbic system or basal ganglia

Summary Three pig-tailed macaques were trained to select (match) from a pair of colored images that which they had seen (sample) and responded to 5–15 s previously. The anterior commissure (AC) and/or its radiation, various loci in basal ganglia, hippocampal formation and control areas, (splenium of corpus callosum, precentral gyrus, insular cortex), totalling 40 loci, were each tetanized for 4 s during presentation of the sample image, during the delay period, or when the monkey was required to select the matching image. For several loci in the hippocampal formation tetanization at any phase of the task reduced matching to chance levels and gave evidence of electrical after-discharge; but other comparable hippocampal loci had little or no effect. Response to sample or match stimuli were absent during tetanization of basal ganglia or anterior commissure. When finally made, upon cessation of tetanization, responses were equally correct for basal ganglia and control sites, but for AC were at chance levels.     

Is there a role for the tumor cell integrin αIIbβ3 and cytoskeleton in tumor cell-platelet interaction?

In vitro tumor cell-platelet interaction was examined using B16 amelanotic (B16a) melanoma cells. These tumor cells express the _IIb3-type cytoadhesin. Aggregation studies demonstrated that tumor cell surface _IIb3 mediates the recognition of platelets since pretreatment of tumor cells with antibody against _IIb3 prevents platelet-tumor cell interaction as well as platelet activation measured by aggregometry, platelet eicosanoid metabolism and ultrastructural analysis. In B16a cells, disruption of the microfilaments and intermediate filaments inhibits mobility of _IIb3 on the cell surface. Microtubules do not play a role in receptor mobility, because B16a cells do not possess well-defined microtubules in interphase and colchicine does not affect receptor mobility. Disruption of microfilaments or intermediate filaments results in an inhibition of tumor cell-platelet interaction as evidenced by aggregometry studies and ultrastructural analysis. We suggest that platelet interaction with tumor cells begins with _IIb3-mediated receptor recognition followed by not only platelet activation but also microfilament- and vimentin intermediate filament-dependent tumor cell activation.     

Current concepts of the molecular structure and metabolism of human apolipoproteins and lipoproteins

Summary During the last few years major advances have occurred in our knowledge of the structure, function, and metabolism of the plasma lipoproteins. Twelve human apolipoproteins have been isolated and characterized. The primary structure of apolipoproteins A-I, A-II, C-I, C-II, and C-III have been elucidated. The primary structure of these apolipoproteins contains no unique sequences, however the primary structure of several of the apolipoproteins contain segments which can be modeled into amphipathic helices. The helical segments may be important in protein-protein as well as protein-lipid interactions. The molecular properties of the apolipoproteins have been investigated and shown to undergo self-association with major increases in conformation. The molecular organization of the plasma lipoprotein particle has been studied, and an iceberg-sea model has been proposed. This model emphasizes the micellar organization of the phospholipids, and the possibility of secondary, tertiary as well as quaternary structure of the apolipoprotein associated with the lipoprotein particle.The metabolism of plasma lipoproteins has been extensively analyzed over the last several years. Two general types of apolipoprotein-lipoprotein particle interactions have been recognized. The first type involves a quasi-irreversible interaction between the apolipoprotein and lipoprotein particle, and is exemplified by apolipoprotein B. The second type of interaction is a reversible apolipoprotein-lipoprotein particle interaction. Apolipoproteins A-I, A-II, C-I, C-II, C-III, and E are examples of the reversible interaction. Within this framework two major apoB-lipoprotein particle cascades have been proposed. Apo B-triglyceride rich lipoproteins including chylomicrons and hepatic VLDL undergo sequential triglyceride hydrolysis. Following triglyceride hydrolysis chylomicrons are converted to remnants with hydrated densities principally of VLDL and IDL. Liver apoB-VLDL is converted initially to IDL and finally to LDL. Apolipoproteins which undergo reversible interactions are present in virtually all density fractions and the distribution of these apolipoproteins is determined by the laws of mass action.With these concepts rapid progress has been made in our understanding of apolipoprotein-lipoprotein biochemistry, physiology, and clinical disorders of lipoproteins and atherosclerosis. The next several years will undoubtedly provide further insights into the structure, function, and metabolism of plasma lipoproteins.Based upon the acceptance address to the Kuratorium für die Verleihung des Heinrich-Wieland-Preises, München, October 31, 1980     

Analysis of the effect of barium ions on isolated medullated nerve fibers

Zusammenfassung An der isolierten markhaltigen Nervenfaser wird nach Ba⁺⁺-Zusatz eine Verschiebung der Elektrotonuskurve nach rechts und unten sowie eine Erhöhung des durch einen Einwärtsstrom bestimmter Größe bewirkten Elektrotonuspotentiales gemessen.Diese Ergebnisse werden im Zusammenhang mit früheren Messungen so gedeutet, daß Barium eine sofortige und anhaltende, der Calciumwirkung vergleichbare Erhöhung der Schwelle bewirkt und daß sich dieser Wirkung eine langsam zunehmende Schwellenerniedrigung überlagert, die durch die Abnahme der Kalium permeabilität verursacht wird.Mit 4 Textabbildungen.     

Sublocalization on chromosome 21 of human interferon-alpha receptor gene and the gene for an interferon-gamma response protein

The cellular responses to alpha and beta interferons (IFN- and -) are mediated through the IFN-/ (type I) receptor, while the response to IFN- is mediated through the IFN- (type II) receptor. The receptors for IFN-/ and IFN- are encoded by genes on human chromosomes 21 and 6q, respectively. The presence of chromosome 21q confers both ligand binding and responsiveness to human IFN-/, whereas chromosome 6q confers binding of Hu-IFN-, but not cellular responsiveness on somatic cell hybrids. Chromosome 6q (i.e., the Hu-IFN- receptor gene) and chromosome 21q are both necessary for the cellular response of somatic cell hybrids (from fibroblasts) to Hu-IFN-. It is conceivable that the factor mediating activity through the IFN- receptor is, in fact, the IFN- receptor, or that the two genes are distinct but part of an interferon response region. Here we more precisely localize on human chromosome 21 the genes for the IFN- receptor and for the factor(s) mediating the action of IFN- through the chromosome 6-encoded receptor. Hamster-human somatic cell hybrids containing various fragments of human chromosome 21 were used. The presence of the human IFN-/ receptor was determined by binding³²P-labeled human IFN- to cells, covalently cross-linking the [³²P]IFN--receptor complex, and analyzing it by SDS-polyacrylamide gel electrophoresis. The presence of the IFN- receptor-related factor mediating cellular responsiveness was determined by HLA induction in hybrid cells containing the IFN- receptor (chromosome 6q), a transfected copy of the human HLA-B7 gene, and various portions of chromosome 21. In all hybrids examined, the two genes cosegregate. Specifically, both genes are localized to the region of chromosome 21 containing the markers D21S58, D21S65, and GART and appear to be proximal to D21S58. The implications for IFN action are discussed.     

Identification and quantitation of cortisol metabolites in rat liver homogenate and -slices

Summary Cortisol-1, 2-H³ was incubated with rat liver homogenate and/or rat liver slices in the presence of a NADPH-generating system. The following metabolites could be identified in adult male rats: -cortol, allo--cortol, 3-allo--cortol, 20-hydroxy-cortisol, 11, 17, 20, 21-tetrahydroxy-5-pregnan-3-one, 3-allotetrahydrocortisol, tetrahydrocortisol, trace amounts of allotetrahydrocortisol and two highly polar metabolites only partly identified. In female rats only tetrahydrocortisol, allotetrahydrocortisol and allodihydrocortisol could be detected in significant amounts.The radioactive metabolites mentioned above were localized and quantitated on paper chromatograms by a 4-radiochromatogram scanner. A nearly perfect correlation was found between these results so obtained and those given by liquid-scintillation counting of each metabolite after its elution from the paper.Part of this work was supported by grant n° 695 of the National Fonds voor Wetenschappelijk Geneeskundig Onderzoek.Stagiair of the Nationaal Fonds voor Wetenschappelijk Onderzoek.     

Eine neue Bestimmung der Neutralfette im Blutserum und Gewebe

Zusammenfassung Die Neutralfette im Blutserum und Gewebe lassen sich über Glycerin exakt ermitteln. Freies und nach alkoholischer Verseifung nachweisbares Gesamt-Glycerin werden mit Glycerokinase in einer dreistufigen enzymatischen Nachweisreaktion im Mikroverfahren bestimmt. Die Differenz wird als Glycerid-Glycerin angesprochen. Reaktionsprinzip, Durchführung der Methode und Berechungsweise werden ausführlich besprochen.Für freies Glycerin werden 0,2 ml Serum, für Gesamtglycerin etwa 0,007–0,015 ml Serum äquivalente Hydrolysatmengen in den Test eingesetzt. Bei einer Empfindlichkeit von 0,0008 µMol (wenn bei 340 nm, bzw. 0,0015 µMol Glycerin, wenn bei 366 nm gemessen wird), können noch 1/20 bis 1/10 des im Normalserum vorhandenen freien bzw. Gesamtglycerins mit den Standardansätzen erfaßt werden. Die obere Nachweisgrenze reicht dann bis 0,15 bzw. 0,3 µMol Glycerin, das entspricht der 8- bzw. 15fachen Normalmenge für freies und Gesamtglycerin. In den angegebenen Grenzen liegen die über Glyceridglycerin nachweisbaren Triglyceridkonzentrationen. Empfindlichkeit und obere Nachweisgrenze können durch andere Serum- bzw. Hydrolysatmengen in weiten Grenzen variiert und der jeweiligen Fragestellung angepaßt werden.

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Summary Triglycerides in blood serum and tissue can be identified exactly by means of glyceride-glycerol. Free and total glycerol, measurable after alcoholic saponification, are determined by glycerolkinase in a three-step enzymatic proof-reaction by means of micro-methods. The difference between total and free glycerol is called glycerideglycerol. Reaction principles, working instructions and the calculation will be discussed in detail.The sensitivity of the standard test runs to 0,0008 respeccively 0,0015 µMol glycerol or 1/20 resp. 1/10 of the normal contentrations. The upper proof limit is at 0,15 respectively 0,3 µMol glycerol per test. This is equal to 8–15 times more than the normal of free and total glycerol. Sensitivity and upper proof limit can easily by varied and adapted to the formulation of the question.

     

Further observations on the morphogenesis of human rotavirus in MA 104 cells

Summary Human rotavirus KUN strain was cultivated in a fetal rhesus monkey kidney cell line, MA 104 cells. Four types of virus particles in cells infected with KUN strain were clearly identified: nucleoid cores, single-shelled particles, double-shelled particles, and membrane band, enveloped particles. Enveloped particles were found only in the thin sections of infected cells. When first visible, the virus precursors appeared at the ribosome free membrane of rough endoplasmic reticulum (RER), increasing in size while simultaneously being coated with nucleocapsid, inner shell. Single-shelled particles were also synthesized within bundles of filaments of viroplasm in the cytoplasma. During subsequent virus maturation two types of budding processes were observed. Double-shelled particles arising at the RER membrane entered the cisternae of the RER through an exocytosis-like process. In contrast, the enveloped particles developed in the cisternae by being completely enclosed with RER membrane, and later during cytolysis released the single-shelled particles. These enveloped virus particles appeared to be the result of inefficient virus maturation at the last stage of outer capsid formation.With 11 Figures     

Synergistic effects of tumour necrosis factor-α and interferon-γ on feline haemopoietic progenitors

Pathogenic mechanisms that underlie feline leukaemia virus subgroup-C (FeLV-C) induced erythroid aplasia are unknown. FeLV-C infection is associated with higher serum levels of interferon- (IFN-) and tumour necrosis factor- (TNF-), which may act synergistically to cause haemopoietic suppression. In the present studies, the synergistic effects of TNF- and IFN- on feline bone marrow progenitors in vitro were evaluated. Bone marrow mononuclear cells from specific-pathogen-free cats were exposed to TNF- (100 and 200 pg/ml) and IFN- (100 or 200 units/ml), alone or in combination, for 2 h before plating for clonal assays of colony forming units. Our results show that TNF- and IFN- in combination caused marked suppression of feline colony forming units-erythroid (CFU-E), burst forming units-erythroid (BFU-E), and colony forming units-fibroblasts (CFU-F), whereas colony forming units-granulocyte/macrophage (CFU-GM) were minimally affected. The same concentrations of TNF- and IFN- alone had minimal effects on CFU-E, BFU-E and CFU-F. These results suggest that TNF- and IFN- may play a significant role in regulating haemopoiesis in cats and may be involved in the pathogenesis of erythroid aplasia in cats infected with feline leukaemia virus.