Transfer of the ADA gene into bone marrow cells and peripheral blood lymphocytes for the treatment of patients affected by ADA-deficient SCID

Severe combined immunodeficiency (SCID) caused by deficiency of the enzyme adenosine deaminase (ADA) is the first genetic disorder considered for human somatic cell gene therapy. ADA-SCID patients can be cured by HLA-matched sibling donor bone marrow transplantation. Alternative transplantation strategies as well as enzyme replacement are being tested in those patients who do not have a suitable matched sibling donor. Some ADA-SCID patients may not be candidates for cytoablation due to infectious damage to the lung or liver, or may have a milder phenotype that does not justify the risks associated with haploidentical bone marrow transplantation. Replacement therapy with PEG-ADA has resulted in improvement in growth, a variable increase in the number of peripheral blood lymphocytes, and a decrease in the incidence of severe infections. Another approach to the treatment of severe genetic diseases is now represented by somatic cell gene therapy. We and others have conducted experiments in vitro and in vivo that have documented that T-lymphocytes are suitable vehicles for gene transfer. Although the pluripotent stem cell remains the ideal target cell for somatic cell gene therapy of disorders of the hematopoietic system, the use of T-lymphocytes as gene therapy vehicles is specifically indicated for ADA-deficient patients where they represent the affected cells. Furthermore, the selective engraftment of T-cells only, following bone marrow transplantation, has resulted in reconstitution of cellular and humoral immunity. A model for the functional analysis in vivo of the human immune system has been utilized for the preclinical evaluation of this approach.(ABSTRACT TRUNCATED AT 250 WORDS)

Soluble tumor necrosis factor (TNF) receptors are effective therapeutic agents in lethal endotoxemia and function simultaneously as both TNF carriers and TNF antagonists

Two forms (monomeric or dimeric) of the extracellular, ligand-binding portion of the human p80 cell-surface receptor for TNF were used to antagonize TNF activity in vitro and in vivo. The dimeric sTNFR:Fc molecule was a more potent inhibitor of TNF than the monomeric sTNFR (50 to 1000x), as assessed in vitro by inhibition of TNF binding or bioactivity and in vivo by protection of mice from an otherwise lethal injection of LPS. Surprisingly, the dimeric sTNFR:Fc construct demonstrated a beneficial effect even when administered 3 h after a lethal LPS injection (i.e., after serum TNF levels had peaked and receded). To study the mechanism by which the soluble TNFR functions in vivo, serum TNF levels were examined in mice given LPS in the presence or absence of soluble receptor. Administration of a mortality-reducing dose of sTNFR:Fc ablated the rise in serum TNF bioactivity that normally occurs in response to LPS. However, TNF bioactivity was revealed in these "TNF-negative" serum samples when the L929 bioassay was modified by inclusion of a mAb that blocks the binding of murine TNF to the human soluble TNFReceptor. These results indicate that the absence of direct cytolytic activity in the L929 assay was caused by neutralization of TNF, rather than to an absence of TNF in the serum. Moreover, administration of either monomeric sTNFR or low doses of dimeric sTNFR:Fc actually resulted in increased serum TNF levels compared to mice given LPS but no soluble receptor. However, these "agonistic" doses of soluble receptor did not lead to increased mortality when an LD60 dose of LPS was given. Thus, dimeric sTNFR are effective inhibitors of TNF and under some circumstances function simultaneously as both TNF "carriers" and antagonists of TNF biologic activity.

The ancestral IncP replication system consisted of contiguous oriV and trfA segments as deduced from a comparison of the nucleotide sequences of diverse IncP plasmids

In most plasmids which have been studied to date the functions required for plasmid replication are clustered in a 2-3 kb region. However, in all known naturally occurring plasmids of the Escherichia coli incompatibility group P the essential replication functions, oriV, the vegetative replication origin and trfA, which encodes proteins essential to activate oriV, are separated by blocks of DNA consisting of either known genes conferring resistance to antimicrobial agents and/or putative transposable elements. Nucleotide sequence comparisons reported here reveal that these blocks of DNA have inserted at different points into a backbone of DNA common to IncP plasmids. The results indicate that in the common ancestor of present IncP plasmids oriV and trfA must have been contiguous, whilst a rho-independent transcriptional terminator, now lost in IncP alpha plasmids, may have prevented trfA operon transcription from interfering with the activity of oriV.

Soluble tumor necrosis factor (TNF) receptors are effective therapeutic agents in lethal endotoxemia and function simultaneously as both TNF carriers and TNF antagonists

Two forms (monomeric or dimeric) of the extracellular, ligand-binding portion of the human p80 cell-surface receptor for TNF were used to antagonize TNF activity in vitro and in vivo. The dimeric sTNFR:Fc molecule was a more potent inhibitor of TNF than the monomeric sTNFR (50 to 1000x), as assessed in vitro by inhibition of TNF binding or bioactivity and in vivo by protection of mice from an otherwise lethal injection of LPS. Surprisingly, the dimeric sTNFR:Fc construct demonstrated a beneficial effect even when administered 3 h after a lethal LPS injection (i.e., after serum TNF levels had peaked and receded). To study the mechanism by which the soluble TNFR functions in vivo, serum TNF levels were examined in mice given LPS in the presence or absence of soluble receptor. Administration of a mortality-reducing dose of sTNFR:Fc ablated the rise in serum TNF bioactivity that normally occurs in response to LPS. However, TNF bioactivity was revealed in these "TNF-negative" serum samples when the L929 bioassay was modified by inclusion of a mAb that blocks the binding of murine TNF to the human soluble TNFReceptor. These results indicate that the absence of direct cytolytic activity in the L929 assay was caused by neutralization of TNF, rather than to an absence of TNF in the serum. Moreover, administration of either monomeric sTNFR or low doses of dimeric sTNFR:Fc actually resulted in increased serum TNF levels compared to mice given LPS but no soluble receptor. However, these "agonistic" doses of soluble receptor did not lead to increased mortality when an LD60 dose of LPS was given. Thus, dimeric sTNFR are effective inhibitors of TNF and under some circumstances function simultaneously as both TNF "carriers" and antagonists of TNF biologic activity.

ICP4, the major transcriptional regulatory protein of herpes simplex virus type 1, forms a tripartite complex with TATA-binding protein and TFIIB

The ICP4 protein of herpes simplex virus can either increase or decrease the rate of transcription mediated by RNA polymerase II, depending on the target promoter. The interplay of DNA-protein and protein-protein contacts determining ICP4 function has yet to be characterized, and consequently the molecular mechanism by which the protein acts remains unclear. ICP4 can transactivate minimal promoters containing only TATA homologies, and therefore it is reasonable to hypothesize that ICP4 works by influencing the TATA-dependent assembly of general transcription factors via specific protein-protein interactions. This study directly addresses this hypothesis by determining whether ICP4 affects the assembly of general transcription factors on templates bearing a TATA box and an ICP4-binding site. Using gel retardation and footprinting assays, we found that ICP4 forms a tripartite complex with TFIIB and either the TATA-binding protein (TBP) or TFIID. The formation of this complex was not the result of simple tripartite occupancy of the DNA but the consequence of protein-protein interactions. In the presence of all three proteins, the affinity of ICP4 and TBP for their respective binding sites was substantially increased. Using mutant derivatives of ICP4 and defective versions of promoters, we also demonstrated that the ability of ICP4 to regulate gene expression correlated with its ability to form a tripartite complex with TFIIB and TBP in vitro.

DNA photolyase repairs the trans-syn cyclobutane thymine dimer

DNA photolyases catalyze the splitting of the cyclobutane ring joining the two dihydropyrimidines of a pyrimidine dimer by a photoinduced electron-transfer reaction. Previous studies concluded that photolyase repairs only the cis-syn form of the eight stereoisomers of the cyclobutane pyrimidine dimer (Pyr[ ]Pyr). In this study we found that Escherichia coli photolyase binds to the trans-syn-I isomer of T[ ]T with about 10(4)-fold lower affinity than the cis-syn isomer but it repairs it relatively efficiently.

CD30 antigen, a marker for Hodgkin's lymphoma, is a receptor whose ligand defines an emerging family of cytokines with homology to TNF

CD30 is a surface marker for neoplastic cells of Hodgkin's lymphoma and shows sequence homology to members of the tumor necrosis factor (TNF) receptor superfamily. Using a chimeric probe consisting of the extracellular domain of CD30 fused to truncated immunoglobulin heavy chains, we expression cloned the cDNA cognate from the murine T cell clone 7B9. The encoded protein is a 239 amino acid type II membrane protein whose C-terminal domain shows significant homology to TNF alpha, TNF beta, and the CD40L. Cross-hybridization to an induced peripheral blood T cell cDNA library yielded the human homolog, which is 72% identical at the amino acid level. The recombinant human ligand enhances the proliferation of CD3-activated T cells yet induces differential responses, including cell death, in several CD30+ lymphoma-derived clones. The human and murine genes map to 9q33 and the proximal region of chromosome 4, respectively.

Temperature dependence of the phosphorescence quantum yield of various alpha-lactalbumins and of hen egg-white lysozyme

The radiative quantum yield, phi op, of the triplet state of human alpha-lactalbumin (HLA) has been measured in the temperature range between 6 K and the softening point of the aqueous glass (approximately 150 K). phi op has little temperature dependence below approximately 30 K, but above this it decreases sharply with increasing temperature. The unusual temperature dependence is fitted by a phenomenological two-state model in which the phosphorescence originates primarily from a donor, tryptophan (Trp) 104, and an acceptor, Trp 60, the populations of which are coupled by a thermally activated triplet-triplet energy transfer process. The model assumes that the acceptor (Trp 60) triplet state undergoes radiationless deactivation by a proximal disulfide residue, while the donor (Trp 104) has no such extrinsic quencher. The decrease of phi op with increasing temperature is accounted for by the thermally activated triplet-triplet energy transfer process. The disulfide quenching rate constant itself is assumed to be temperature independent, in accord with recent measurements of simple disulfide quenching in long chain snake venom neurotoxins (Schlyer, B. D., E. Lau, and A. H. Maki. 1992. Biochemistry. 31:4375-4383; Li, Z., A. Bruce, and W. C. Galley. 1992. Biophys. J. 61:1364-1371). We find that the phosphorescence quenching in HLA occurs with an activation energy of 97 cm-1, which we associate with a barrier to the energy transfer process. The data are fit well by the model if we assume a value for the temperature-independent disulfide quenching constant of kQ > 3 s-1 that is consistent with recent measurements on indole-disulfide model systems (Li, Z., A. Bruce, and W. C. Galley. 1992. Biophys. J. 61:1364-1371). Similar results are reported for bovine alpha-lactalbumin (BLA) and for hen egg-white lysozyme (HEWL) that contains the structural equivalents of Trp 104 and Trp 60 of HLA. HLA provides the best agreement with calculations since it is the simplest, lacking Trp 26, a residue not considered in the model, that probably contributes significantly to the phosphorescence of BLA, guinea pig alpha-lactalbumin (GPLA), and HEWL. GPLA, which contains Trp 104 but lacks Trp 60, shows qualitatively less thermally induced phosphorescence quenching than HLA, BLA, and HEWL, thus supporting the postulated quenching model.

Preparation and characterization of a set of deoxyoligonucleotide 49-mers containing site-specific cis-syn, trans-syn-I, (6-4), and Dewar photoproducts of thymidylyl(3'-->5')-thymidine

Deoxyoligonucleotide 49-mers containing a central cis-syn, trans-syn-I, (6-4), or Dewar photoproduct of TpT were constructed for use in repair and replication studies by ligation of shorter photoproduct-containing oligonucleotides. A (6-4) product-containing 6-mer was prepared in 3.4% yield by 254 nm irradiation of d(AATTAA) and converted in nearly quantitative yield to the Dewar isomer by irradiation with Pyrex- and Mylar-filtered medium-pressure mercury arc light. d(CGAATTAAGC) containing a site-specific cis-syn or trans-syn-I dimer was prepared via automated solid-phase DNA synthesis utilizing photoproduct building blocks. The photoproduct-containing 49-mers were characterized by their susceptibility to base cleavage and a number of enzymes routinely used to map the sites of DNA photoproduct formation. 1 M piperidine at 90 degrees C cleaved the Dewar product faster than the (6-4) product, but did not cleave the cyclobutane dimers. The 3'-->5' exonuclease activity of T4 DNA polymerase was completely blocked by all the lesions except the (6-4) product, which it slowly bypassed. T4 endonuclease V did not cleave the (6-4) or Dewar photoproduct, but unexpectedly cleaved the trans-syn-I dimer at most 1% the rate of the cis-syn dimer in double-stranded DNA. The trans-syn-I dimer was cleaved at a 50-fold higher rate in double- than in single-stranded DNA. Escherichia coli photolyase was found to be specific for the cis-syn dimer at low concentrations. Implications of this work to methodology for mapping and quantifying DNA photoproducts are also discussed.

Effect of sequence, adduct type, and opposing lesions on the binding and repair of ultraviolet photodamage by DNA photolyase and (A)BC excinuclease

The cis,syn and (6-4) products of dipyrimidine sites are the major mutagenic and lethal UV photoproducts in DNA. To investigate their relative susceptibilities to repair and other factors such as sequence context and lesions in the complementary strand that might influence repair efficiencies, we constructed 49-mer duplexes containing site-specific photoproducts of thymidylyl(3',5')thymidine sites at central locations. Using these substrates, we measured the binding of Escherichia coli DNA photolyase to cis,syn dimers in four sequence contexts and to two cis,syn dimers in close proximity and on opposing strands. We found that the sequence within a 10-base pair region had little effect on binding and that two enzyme molecules bound to substrate containing two dimers in the 5'-staggered orientation, but not in the 3'-staggered one. Similarly, the excision of a cis,syn dimer by (A)BC excinuclease was not influenced by the sequence in the immediate vicinity of the dimer, and the enzyme was active on 5'-staggered cis,syn dimers, but not on 3'-staggered ones. Of special significance, we found that (A)BC excinuclease removed the cis,syn, trans,syn-I, (6-4), and Dewar photoproducts at vastly differing relative rates of 1:6:9:9, respectively.

Molecular and biological characterization of a ligand for CD27 defines a new family of cytokines with homology to tumor necrosis factor

CD27 is a surface antigen found on T and B cells that has homology to a family of molecules including the receptors for tumor necrosis factor (TNF) and nerve growth factor. A cDNA encoding a ligand for CD27 was isolated by a direct-expression cloning strategy using a fusion protein composed of the extracellular domain of CD27 linked to the constant domain of a human immunoglobulin G1 molecule as a probe. The predicted protein product is a type II transmembrane protein whose gene maps to 19p13 and that shows homology to TNF and the ligand for CD40. Biological characterization indicates that the cloned ligand induces the proliferation of costimulated T cells and enhances the generation of cytolytic T cells.

Synthesis and antibody-mediated detection of oligonucleotides containing multiple 2,4-dinitrophenyl reporter groups

A series of non-nucleoside-based 2,4-dinitrophenyl (DNP) phosphoramidites have been prepared and used in the multiple labelling of oligonucleotides during solid-phase synthesis. The length of spacer arm between the DNP label and the oligonucleotide phosphate backbone, and the number of attached DNP groups have both been varied in order to determine the optimum conditions for anti-DNP antibody binding. Detection using enzyme-linked colorimetric techniques showed sensitivity equivalent to that obtainable using biotinylated oligonucleotides.

Analysis of cytokine gene expression in subpopulations of freshly isolated thymocytes and thymic stromal cells using semiquantitative polymerase chain reaction

Using a semi-quantitative polymerase chain reaction (PCR) technique we have examined the expression of a panel of cytokines during thymus development, localizing the expression to individual components of the thymic stroma and thymocytes at different maturational stages. The expression of interleukin (IL)-7, stem cell factor (SCF), IL-1 alpha and granulocyte-monocyte-colony-stimulating factor (GM-CSF) mRNA was mapped to individual stromal cell types, while the expression of IL-1 alpha and GM-CSF, along with interferon (IFN)-gamma and IL-4 was detected in the lymphoid compartment of fetal day (Fd) 14 thymus. The expression of lymphoid-specific cytokines genes was selectively down-regulated in thymocytes undergoing maturation. CD3-/lo4+8+ cells, representing an intermediate stage of thymocyte maturation, were devoid of cytokine gene expression. Their CD3+ progeny, on the other hand, expressed IFN-gamma mRNA, supporting the notion that positive selection of cells for further maturation induces the reexpression of some cytokine genes. The cytokine profiles of the various stromal components differed. Purified major histocompatibility complex class II+ cortical epithelial cells strongly expressed IL-7 and SCF, but only limited expression of IL-1 alpha and GM-CSF could be detected. Fetal mesenchyme, on the other hand, expressed SCF, IL-1 alpha and GM-CSF but not IL-7. The importance of these cytokine profiles in relation to T cell development is discussed.

Patterns of obesity in Missouri

Obesity is a major preventable health problem in Missouri and in the nation. Using survey data, we examined the prevalence of obesity in population subgroups and the overall trend. Prevalence of obesity was higher among blacks, middle-aged persons, and persons with less education or lower family income. Without additional attention, Missouri is unlikely to achieve the year 2000 objective of < or = 20% prevalence of obesity.

Effects of memory from vagal feedback on short-term potentiation of ventilation in conscious dogs

1. We assessed short-term potentiation of ventilation in response to brief systemic normocapnic hypoxaemia in conscious dogs. Four recumbent dogs were exposed to Pa, O2 35-55 mmHg with Pa, CO2 maintained normocapnic for forty to fifty seconds and then abruptly returned to normoxia. Minute ventilation (VI) increased 4- to 5-fold during hypoxia due to both increased tidal volume (VT) and frequency (f). Several trials of hypoxic exposure with normoxic restoration were conducted with animals intact and following bilateral cold blockade of the cervical vagus nerves sufficient to block completely the Hering-Breuer reflex. 2. In the vagally intact dog, when normoxia was restored immediately following normocapnic hypoxia (PET, O2 = 40 Torr), expiratory time (TE) was prolonged to 190 +/- 68% of control (mean +/- S.E.M., range 53-350%) on the second or third breath and then returned slowly to control values on subsequent breaths. The prolongation of TE following removal of the hypoxic stimulus was positively correlated with the magnitude of the peak VT reached during hypoxic exposure. However, VT and VI remained significantly greater than control over a twenty second or four-breath period following hypoxia. 3. In the vagally blocked dog, no prolongation of TE was observed following isocapnic hypoxia; nor was TE following hypoxia correlated with the magnitude of the VT during hypoxia. The time constants of decay of VI, VT and f back to control, following hypoxia averaged 16, 19 and 9 s, respectively. 4. We conclude that short-term potentiation of ventilatory output following peripheral chemoreceptor hypoxic stimulation does exist in the awake dog, but the stimulatory after-effect is masked and TE is prolonged by a 'memory' of inhibitory vagal feedback. The magnitude of this inhibitory after-effect on TE prolongation increases in proportion to the increase in tidal volume achieved during the hypoxaemia. 5. This inhibitory effect of vagal memory may contribute to instability of breathing pattern and apnoea following transient disturbances in ventilatory output.

Enterobacter taylorae, a new opportunistic pathogen: report of four cases

Severe nosocomial infections due to Enterobacter taylorae (formerly known as CDC Enteric Group 19) are described in four patients. Unlike most members of the Enterobacter genus, the isolates were not susceptible to penicillins or cephalosporins. Restriction endonuclease analysis of E. taylorae DNA obtained from three patients identified two distinct strains. One strain was found in two patients, suggesting a common source which we were not able to identify. We postulate that in patients harboring E. taylorae, the combination of cephalosporin therapy and instrumentation enables this organism to become an opportunistic pathogen.

Localization of the CYP2D gene locus to human chromosome 22q13.1 by polymerase chain reaction, in situ hybridization, and linkage analysis

Using a combination of somatic cell hybrids, in situ hybridization, and linkage mapping, we have been able to localize the cytochrome P450 CYP2D6 gene to chromosome 22 in the region q13.1. Linkage analysis, using locus-specific primers, showed a maximum sex-average lod score of 8.12 (theta = 0.00) between the marker pH130 (D22S64) and CYP2D6, of 6.92 (theta = 0.00) between the marker KI839 (D22S95) and CYP2D6, and of 4.80 (theta = 0.036) between the platelet-derived growth factor beta subunit gene (PDGFB) and CYP2D6.

Tissue-specific regulation of shell gland calbindin D28K biosynthesis by estradiol in precociously matured, vitamin D-depleted chicks

Provision of Ca2+ for egg shell calcification in the avian uterus [egg shell gland (ESG)] derives mostly from vitamin D-dependent intestinal Ca2+ absorption from the diet. Ca2+ absorption is strongly linked to the intestinal vitamin D-dependent calbindin D28K (D28K) concentration. The laying hen ESG also contains D28K, and again, Ca2+ transport into the shell appeared to be linked to the ESG D28K concentration. However, evidence is now presented that ESG D28K synthesis may be estradiol (E2) dependent and vitamin D independent under certain conditions. One-day-old female chicks fed a vitamin D-free diet for as long as 6 weeks and then repeatedly injected im with E2 for up to 3 more weeks developed frank rickets, but possessed precociously matured reproductive tracts. While the tiny presumptive ESGs of nonestrogenized vitamin D-depleted chicks were devoid of D28K, the highly developed ESG, including the isthmus, of estrogenized chicks contained D28K. The ESGs of nonestrogenized, vitamin D-replete chicks also exhibited no development or detectable D28K. Regardless of whether vitamin D depleted or replete, estrogenized chick ESG contained similar D28K and D28K mRNA concentrations. Immunohistochemical techniques showed that the endometrial cellular localization of both D28K and Ca(2+)-ATPase (Ca2+ pump) in estrogenized chicks was similar to that in mature laying hens. There was no trace of D28K, nor was there any stimulation of Ca2+ absorption, in duodenum of vitamin D-free, immature chicks regardless of E2 treatment. As expected, both D28K and D28K mRNA were present in vitamin D-replete chick duodenum. We conclude that in E2-treated chicks, ESG D28K gene expression may be vitamin D independent and E2 dependent. This is the first clear demonstration of hormone-dependent tissue-specific D28K gene expression in the chick.

Effects of specific carotid body and brain hypoxia on respiratory muscle control in the awake goat

1. We assessed the effects of specific brain hypoxia on the control of inspiratory and expiratory muscle electromyographic (EMG) activities in response to specific carotid body hypoxia in seven awake goats. We used an isolated carotid body perfusion technique that permitted specific, physiological, steady-state stimulation of the carotid bodies or maintenance of normoxia and normocapnia at the carotid bodies while varying the level of systemic, and therefore, brain oxygenation. 2. Isolated brain normocapnic hypoxia of up to 1.5 h duration increased inspired minute ventilation (VI) by means of increases in both tidal volume (VT) and respiratory frequency (fR). Electromyographic activities of both inspiratory and expiratory muscles were augmented as well. These responses were similar to those produced by low levels of whole-body normoxic hypercapnia. We conclude that moderate levels of brain hypoxia (Pa,O2 approximately 40 mmHg) in awake goats caused a net stimulation of ventilatory motor output. 3. Hypoxic stimulation of the carotid bodies alone caused comparable increases in VT and fR, and EMG augmentation of both inspiratory and expiratory muscles whether the brain was hypoxic or normoxic. These responses were quite similar to those obtained over a wide range of whole-body normoxic hypercapnia. We conclude that the integration of carotid body afferent information is not affected by moderate brain hypoxia in awake goats. 4. We found no evidence for an asymmetrical recruitment pattern of inspiratory vs. expiratory muscles in response to carotid body hypoxia or in response to brain hypoxia alone. 5. Our data support the concept that moderate brain hypoxia results in a net stimulation of respiratory motor output. These findings question the significance of 'central hypoxic depression' to the regulation of breathing under physiological levels of hypoxaemia in the awake animal.

Transdominant inhibition of herpes simplex virus growth in transgenic mice

A mutant allele (X25) of an essential regulatory protein, ICP4, encoded by herpes simplex virus (HSV) has been shown to have a transdominant, negative effect on the activity of the wild-type protein, resulting in the inhibition of virus growth in vitro. The X25 protein appears to exert its transdominant effect by sequestering functional ICP4 monomers into nonfunctional, heterodimeric complexes (A. Shepard, P. Tolentino, and N. A. DeLuca, 1990, J. Virol. 64, 3916-3926). In order to assess the antiviral potential of X25 in vivo, four transgenic mouse lines were generated bearing 1 to 10 copies of a DNA fragment encoding the mutant allele. Monolayers of embryonic cells prepared from each of the lines expressed the transgenic X25 protein. When challenged via the eye, every line exhibited at least some enhanced resistance to HSV infection. In the best line, transgenic animals exhibited a statistically significant (> 95% confidence) 5- to 13-fold lower eye swab titer relative to their nontransgenic littermates at Day 1 postinfection. A similar reduction in titer was observed in the trigeminal ganglia at Day 3 postinfection. These results indicate that the X25 protein is able to exert a significant antiviral effect in vivo.

Alterations in cellular calcium handling as a result of systemic calcium deficiency in the developing chick embryo: I. Erythrocytes

Chick embryos rendered calcium (Ca) deficient by shell-less (SL) culture develop hypertension and tachycardia. Since hypocalcemia is accompanied by hypernatremia systemically but not by lower cellular Ca (Koide and Tuan, 1989), we speculate that cellular Ca handling may be altered in the SL embryo, perhaps involving Na transport. Using erythrocytes (RBC) from day-14 SL and normal (NL) embryos as the experimental cell, cellular Ca handling was studied under varying extracellular osmotic and ionic conditions by analyzing 45Ca uptake and cell volume regulation. Two agents, p-chloromercuriphenylsulfonate (PCM), and inosine/iodoacetamide (INI) were used to treat the RBCs to modify plasma membrane ion permeability and to deplete cellular ATP, respectively. Other cellular functions and activities related to Ca homeostasis, including ATP content and Ca(2+)-ATPase activity, were also analyzed. These analyses showed: (1) in NaCl, Ca uptake was similar in NL and SL cells, except after INI treatment, which resulted in slower Ca uptake by the SL cells, (2) in choline and sucrose, Ca uptake by SL RBCs was higher, (3) Ca uptake by RBCs of both embryos changed depending on the osmotic agent (Na < K < or = choline < sucrose), (4) Ca(2+)-ATPase activity was higher in SL RBC, although there was no change in the size or charge of the enzyme, and (5) in any osmotic agent, cellular Na was significantly lower, whereas cellular K was higher, in SL RBC. Based on these results, three features of RBC Ca handling were apparent: (1) Na-Ca exchange was functional and was more active in SL RBCs, (2) Ca uptake was dependent on the total ionic electrochemical gradient but not on bulk H2O movement, and (3) Ca pumping out capacity was directly correlated with Ca(2+)-ATPase activity. Elevated Ca uptake in sucrose-treated SL RBC is therefore indicative of its greater ion permeability. Taken together, these findings indicate that cellular Ca handling of the RBCs of SL chick embryos is characterized by a more active Na-Ca exchange system, greater ion permeability, and higher Ca pumping out capacity, thereby suggesting an up-regulated Ca handling function in the SL RBCs. The abnormal cellular Ca handling may be a direct result of the systemic Ca deficiency of the SL chick embryo and may be functionally related to its hypertension and tachycardia.

Investigation of glomerular lesions in dogs with acute experimentally induced Ehrlichia canis infection

Six male Beagles were inoculated with Ehrlichia canis. Transient proteinuria was confirmed during the acute phase of infection by serial determination of urinary protein-to-creatinine ratio. Peak urine protein loss, consisting principally of albumin, was observed 2.5 to 3.5 weeks after inoculation. Renal biopsy specimens were obtained before inoculation, during peak proteinuria, and 10 weeks after inoculation when proteinuria had resolved. Renal tissue was evaluated by use of light, immunofluorescent, and electron microscopy to correlate specific glomerular lesions with development of proteinuria. Histologic examination revealed perivenular and interstitial infiltrates of lymphocytes and plasma cells localized principally to the renal cortex. Glomerular lesions were minimal to absent. Immunofluorescent staining revealed moderate to marked deposition of anti-canine IgG and IgM in the glomerular tufts and mesangium. Depositions of anti-canine complement factor C3 were not observed. Immunofluorescent staining persisted 10 weeks after inoculation, despite resolution of proteinuria, and probably represented passive trapping of immunoglobulins. Ultrastructural examination revealed fusion of podocyte processes that coincided with development of proteinuria. Electron-dense deposits or changes in the basement membrane were not observed. Morphometric measurements of average podocyte process length and percentage of coverage of basement membrane by podocyte processes were used to quantify the degree of process fusion. Both measurements increased significantly (P < 0.05) during peak proteinuria, and returned to preinoculation values when proteinuria had resolved 10 weeks after E canis inoculation. These findings indicated possible minimal-change glomerulopathy, rather than immune-complex glomerulonephritis, during acute E canis infection and could explain transient proteinuria without histologic evidence of glomerular disease.