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Biomedical subjects

F S Stals

Publications and source records attributed to F S Stals.

At least 19 recordsLinked to original sources

Multiple organ involvement during experimental cytomegalovirus infection is associated with disseminated vascular pathology.

Since much of the pathogenesis of cytomegalovirus (CMV) disease is still unknown and vascular involvement may be of importance a rat model was used to study the nature and course of CMV-induced vascular pathology. In this model, local CMV infection was established by subcutaneous inoculation of rat-specific CMV (RCMV) in the sole of the foot. Sings of endothelial activation, including leucocyte adhesion, preceded detectable RCMV infection of these cells. ultimately, vasculitis and thrombotic occlusion were accompanied by diffuse tissue inflammation and necrosis. Generalized RCMV infection was induced in rats by intraperitoneal administration of the virus, which resulted in multiple organ pathology, including haemorrhages, inflammation, and gastrointestinal ulceration. RCMV-encoded antigens were found especially in mononuclear inflammatory cells in the organs and peripheral blood. In addition, multiple haemorrhages and disturbed haematological parameters indicated diffuse intravascular coagulopathy. In conclusion, this study provides evidence for extensive vascular involvement and haematological consequences during disseminated CMV infection. The nature and chronology of RCM-induced pathological vascular events were demonstrated, indicating the importance of endothelial damage. These data and further study may lead to a better understanding of the pathogenesis of CMV multiple-organ disease.

Animals

Effective treatment of experimental cytomegalovirus-induced encephalo-meningitis in immunocompromised rats with HPMPC.

Cytomegalovirus (CMV)-induced encephalomeningitis is a dramatic complication in patients with the acquired immunodeficiency syndrome (AIDS) and treatment of this infection remains a major clinical problem. In order to study the pathogenesis and treatment of CMV-induced encephalomeningitis, we experimentally induced intracranial rat CMV (RCMV) infection in rats that were immunosuppressed by total body X-irradiation. CMV infection was monitored by viral plaque assay for estimation of the viral load. CMV-induced pathology, the presence of CMV-infected cells, as well as the presence of T-lymphocytes and monocytes/macrophages were studied by histopathologic and immunohistochemical staining techniques. The meninges showed CMV infection in mononuclear infiltrative cells and in endothelium of small blood vessels 8 days after intracerebral inoculation. This was accompagnied by multiple haemorraghes and inflammatory cell infiltration. The infection and inflammatory response persisted for at least 21 days p.i. Animals were treated with (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC), 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), hyperimmune serum (HIS) and both DHPG and HIS combined. Treatment with one dosage of HPMPC at 20 mg/kg effectively reduced virus titers. However, all other treatment modalities were not effective. In conclusion, the pathology of RCMV-induced encephalomeningitis in immunocompromised rats closely resembles that of AIDS patients. The infection is effectively treated by HPMPC.

Animals

IgM antibody detection of ppUL80A and ppUL32 by immunoblotting: an early parameter for recurrent cytomegalovirus infection in renal transplant recipients.

The value of IgM detection for the early diagnosis of an active cytomegalovirus (CMV) infection in renal transplant recipients was evaluated prospectively. Sequential serum samples obtained from 22 allograft recipients with active CMV infection were tested for the presence of CMV-specific immunoglobulin M antibodies (IgM) by an enzyme-linked immunosorbent assay (ELISA) and a microparticle enzyme immunoassay (MEIA) and were compared with the Western-immunoblotting technique (IB). The time course of CMV IgM antibody detection was evaluated in relation to the shell vial assay (SVA), CMV disease, and immunosuppressive regimen. By IB, IgM antibodies against the capsid protein ppUL80a and the basic matrix phosphoprotein ppUL32 were detected in all 22 recipients with active CMV infection. Using the MEIA and the ELISA, the presence of CMV IgM antibodies was detected in 17 (77%) and ten (46%) of these 22 recipients, respectively. The SVA was the earliest parameter for detection of primary CMV infection in seven of nine (78%) recipients, in contrast to two of 13 (15%) patients with recurrent CMV infection (P < .05). The detection of IgM antibodies by IB was the earliest parameter for detection of recurrent CMV infection in seven out of 13 (54%) recipients in contrast to one out of nine (11%) patients with primary CMV infection (P < .05). During a primary CMV infection, the development of an abundant IgM antibody response was associated with recovery from CMV disease and the end of the viremic phase.

Antibodies, Viral

Combinations of ganciclovir and antibody for experimental CMV infections.

The effect of combined treatment with ganciclovir and hyper immune serum (HIS) was evaluated in three animal models. It concerned a generalized CMV infection model, a meningo-encephalitis model and an interstitial lung disease (ILD) model in immunocompromised rats. In the generalized model, the ganciclovir and HIS had a moderate synergistic effect on survival and greatly decreased virus titers in internal organs. In contrast, in the meningoencephalitis model, combined treatment had no effect on the local virus titers and the histopathology. Combined treatment with ganciclovir and HIS, however, effectively abolished CMV-induced ILD.

Animals

Cytomegalovirus induces interstitial lung disease in allogeneic bone marrow transplant recipient rats independent of acute graft-versus-host response.

Interstitial lung disease (ILD) after allogeneic bone marrow transplantation (BMTx) is an important clinical problem in terms of diagnosis, therapy, and pathogenesis. Graft-versus-host disease (GvHD) and cytomegalovirus (CMV) infection seem to be major risk factors for ILD, but their role in the pathogenesis is not well established. We previously reported CMV-induced ILD in allogeneic bone marrow recipient rats, which was prevented by antiviral drug treatment. In this paper, we describe the pathology of ILD in allogeneic bone marrow transplant recipient rats and the relation of ILD with CMV infection and GvHD. Brown Norway rats received an allogeneic (Lewis) BMTx and rat CMV infection, after an allogeneic (Lewis) lung transplantation and immunosuppression. CMV infection was recorded by the amount of infectious virus and viral antigens in the lung. ILD was monitored by the presence of diffuse histopathologic changes in the alveolar septal wall. GvHD was scored by the relative splenic weights and the presence of perivascular infiltrates in the lung. Cells expressing CMV antigens were more numerous in the alveolar septa of the allogeneic recipient lungs than in the syngeneic donor lungs (p < 0.05). The high viral load in the recipient lung of allogeneic BMTx recipient rats was accompanied by diffuse ILD, marked by extensive microvascular damage and congestion of the alveolar septa. ILD was observed neither in the syngeneic donor lung nor in both lungs of mock-infected animals. GvHD was not observed in rat-CMV-infected or in mock-infected animals. Our results indicate that CMV induces microvascular damage, resulting in ILD. This process is independent of GvHD.

Animals

Pathogenicity: animal models.

Animal models offer the opportunity to study the interaction of the virus and the host and to unravel the mechanism in processes such as persistence of the virus and virus-induced pathology. Primary infection results in a generalized infection as shown by the presence of virus in many organs. During viraemia the virus is present in mononuclear cells by which it is transported through the body. In neonates and in immuno-suppressed animals the infection results in multiorgan failure, leading to death. Recent data have shown that infection of endothelial cells in the microvasculature and mononuclear cells seems to be important in the pathogenesis of cytomegalovirus (CMV)-induced disease. After primary infection the virus persists in the body. Although the exact localization of the latent virus is unknown it is clear that during latency viral DNA is present in many organs. By immune suppression the virus can reactivate from its latent state. In addition to the direct complications attributable to the virus itself, CMV has modulating effects on the immune response. Although in some instances the infection leads to immune suppression, the virus infection can also accelerate inflammatory and immune responses. Studies in mice have shown that CMV infection can exacerbate graft-versus-host reactions, and experiments in rats using allogeneic transplants indicate that CMV infection results in enhanced chronic rejection in which acceleration of the immune response is involved. Although the exact mechanism is not clear, recent data indicate that cytokines, such as tumor necrosis factor alpha are involved in these processes.

Acute Disease

Induction of endothelial adhesion molecules by rat cytomegalovirus in allogeneic lung transplantation in the rat.

Cytomegalovirus (CMV) infection is known to be a major risk factor for the development of chronic transplant rejection in heart and lung transplantation. A possible mechanism for the induction of lung transplant rejection by CMV infection is the inflammatory upregulation of adhesion ligand molecules by the viral infection leading to an increased endothelial-leucocyte interaction. To study this question, an experimental model was established in the rat using a rat cytomegalovirus (RCMV) infection and acute lung transplant rejection in left single lung transplantation. The distribution of RCMV, intercellular adhesion molecule-1 (ICAM-1) and its leucocyte receptor CD11a (LFA-1) were investigated by immunohistochemistry. The viral infection was observed in transplant lungs of infected hosts as early as day 11. The expression of ICAM-1 on endothelial cells was induced and enhanced by RCMV infection, and infiltration of CD11a-positive leucocytes found to be increased in infected recipients. An acceleration of the rejection of the allografts by the hosts was found.

Animals

Generalized cytomegalovirus (CMV) infection and CMV-induced pneumonitis in the rat: combined effect of 9-(1,3-dihydroxy-2-propoxymethyl)guanine and specific antibody treatment.

The combined effect of 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG, ganciclovir) and hyper immune serum (HIS) was studied in two different rat models. In the first model, a lethal generalized rat cytomegalovirus (RCMV) infection was established in immunosuppressed Brown Norway (BN) rats. Treatment with DHPG or hyper immune serum (HIS) effectively reduced both mortality rate and virus titers in the liver and lungs. By combined treatment the effective dose of both DHPG and HIS was reduced to 25%. The fractionary effective dose was 0.5, indicating a moderate synergistic effect on survival. Combined treatment also established a significant reduction of virus titers in lungs and liver (P < 0.01), but not in spleen. In the second model, interstitial pneumonia (IP) was established in RCMV-infected immunosuppressed BN rats after allogeneic bone marrow transplantation. IP was characterized by infiltration of mononuclear cells and diffuse thickening of the alveolar septal wall. DHPG reduced virus titers in the lungs but had no effect on IP. In contrast, HIS significantly reduced both virus titers and histopathologic changes in the lungs. Combined DHPG and HIS treatment minimized virus titers in internal organs and CMV-induced IP. Likewise, combined DHPG and control immune serum treatment significantly reduced immunopathologic changes in the lungs.

Animals

Chlamydia trachomatis antibody testing is more accurate than hysterosalpingography in predicting tubal factor infertility.

OBJECTIVE: To compare the likelihood of abnormal Chlamydia trachomatis antibody test results with that of abnormal hysterosalpingography (HSG) test results in patients with tubal factor infertility. DESIGN: Anti-C. trachomatis immunoglobulin G antibodies were determined prospectively in 211 consecutive infertility patients by means of an indirect fluorescent antibody technique. The results were compared with the results of HSG with respect to their predictive value of tubal factor infertility. Likelihood ratio calculations were used. SETTING: University hospital-based, tertiary care infertility clinic. PATIENTS: A series of 211 consecutive infertility patients. INTERVENTIONS: C. trachomatis antibody testing, HSG, laparoscopy. MAIN OUTCOME MEASURES: Likelihood ratios for abnormal C. trachomatis antibody test results and abnormal HSG results in infertility patients, as assessed by laparoscopy. RESULTS: The positive likelihood ratio for C. trachomatis antibody testing was 9.1, indicating a patient with tubal factor infertility to be 9.1 times more likely to have abnormal serology results than a patient without tubal factor infertility. This was superior to HSG, which had a positive likelihood ratio of 2.6 in our study and of 1.6 to 6.1 in the literature. The odds ratio of C. trachomatis antibody testing was 31.5 in our study. Its 90% confidence interval (8.3 to 138.5) did not overlap that of HSG as calculated from a meta-analysis of literature reports (5.3 to 7.9). CONCLUSIONS: C. trachomatis antibody testing is simple, inexpensive, and causes minimal inconvenience to the patient. It is more likely than HSG to be abnormal in patients with tubal factor infertility. C. trachomatis antibody testing deserves to become an integral component of the initial fertility work-up.

Antibodies, Bacterial

Prevention of bacteraemia by systemic ciprofloxacin treatment in rat cytomegalovirus-infected immunocompromised rats.

After total body irradiation (TBI) and subsequent rat cytomegalovirus (RCMV) infection rats developed severe neutropenia and in 90% of these animals Gram-negative bacteraemia was observed. Neutropenia was less severe (P < 0.01) and bacteraemia was not recorded (P < 0.01) in uninfected irradiated control groups. The effect of selective bowel decontamination (SBD) on the bowel flora and the incidence of bacteraemia in RCMV-infected irradiated rats was studied. Animals received ciprofloxacin 2 mg/kg/day, administered by either the oral or the subcutaneous route. After either treatment regimens the numbers of Enterobacteriaceae in the caecum and colon were reduced significantly (from 10(7) to < 10(2) g of faeces), while the total numbers of facultatively aerobic and obligatory anaerobic bacteria and the number of enterococci in the faeces was unaffected when measured 1, 3 and 7 days after the onset of treatment. The effect of ciprofloxacin treatment on the incidence of bacteraemia was recorded in RCMV-infected irradiated groups. Blood and organ cultures were taken 10 days after virus inoculation. The rate of bacteraemia decreased from 80% in untreated RCMV-infected irradiated rats affected by severe RCMV disease to < 10% in the ciprofloxacin treated groups (P < 0.01). The route of treatment did not influence these results. The uninfected irradiated and infected non-irradiated control groups showed no bacteraemia. It is concluded that symptomatic RCMV infection induces severe neutropenia, which predisposes to a high rate of Gram-negative bacteraemia, which can be prevented by eradication of the Gram-negative aerobic bacteria by means of SBD with ciprofloxacin. Systemic treatment seems to be superior for the control of Enterobacteriaceae. This may be especially useful for patients, who cannot be treated effectively by the oral route because of intestinal stasis.

Animals

Tumor necrosis factor alpha promotes replication and pathogenicity of rat cytomegalovirus.

We investigated the role of tumor necrosis factor alpha (TNF-alpha) in the pathogenesis of rat cytomegalovirus (RCMV) infection. TNF-alpha levels found in the sera of radiation-immunosuppressed rats in the course of infection (> 350 pg/ml) correlated with the development of RCMV disease. Administration of anti-TNF-alpha antibodies strongly reduced the severity of pneumonia and led to a reduction in virus titers. In immunocompetent rats, anti-TNF-alpha antibodies also significantly suppressed viral replication. Conversely, administration of TNF-alpha augmented RCMV replication and aggravated the disease signs. In vitro, TNF-alpha enhanced RCMV replication in the macrophage, whereas a reduction of viral replication was observed in fibroblasts, indicating that the effect on viral replication is cell type specific. Besides activation of viral replication and exacerbation of RCMV disease, TNF-alpha also favored lymphoid and hematopoietic tissue reconstitution after irradiation, which may contribute to antiviral resistance and survival. This finding demonstrates the protean nature of TNF-alpha, with both beneficial and adverse effects for the host. Our results suggest that TNF-alpha plays an important role in modulating the pathogenesis of RCMV infection.

Animals

Suppression of rat cytomegalovirus replication by antibodies against gamma interferon.

The role of gamma interferon (IFN-gamma) in the resolution of rat cytomegalovirus (RCMV) infection was investigated. In the spleen, IFN-gamma-producing cells reached maximum numbers on day 7 after infection. Prophylactic treatment with high doses of recombinant rat IFN-gamma exerted antiviral activity in fibroblasts and protected immunosuppressed rats against a lethal RCMV challenge. Remarkably, in immunocompetent rats, neutralization of endogenous IFN-gamma activity significantly reduced the numbers of RCMV antigen-expressing cells in the spleen, the predominant site of viral replication. Moreover, protection of radiation-immunosuppressed infected rats by transferred immune T cells was enhanced by coinjection of IFN-gamma neutralizing antibodies. The observations were paralleled by in vitro findings: low concentrations of IFN-gamma enhanced viral replication in both macrophages and fibroblasts. These data suggest that IFN-gamma can play different and even opposite roles in the regulation of RCMV replication in vivo; T lymphocytes may contribute to the progression of RCMV infection by secreting IFN-gamma.

Animals

Rat cytomegalovirus-induced pneumonitis after allogeneic bone marrow transplantation: effective treatment with (S)-1-(3-hydroxy-2-phosphonyl-methoxypropyl)cytosine.

Two antiviral compounds, (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC) and 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), were evaluated for their effects on rat cytomegalovirus (RCMV)-induced interstitial pneumonitis after allogeneic bone marrow transplantation (BMTx). Eight-week-old Brown Norway rats immunosuppressed by a lethal dose of total body irradiation were inoculated with RCMV and received allogeneic bone marrow cells from Lewis rats. Animals were treated with either HPMPC (20 mg/kg of body weight as a single dose) or DHPG (20 mg/kg as two daily doses for 5 days). The effect of antiviral therapy was monitored by measuring RCMV titers in different organs and the histopathologic changes in lungs at 8 to 10 days postinfection. In RCMV-infected allogeneic BMTx recipients, severe diffuse thickening of alveolar septa (6.02 microns) with a diffuse infiltration of mononuclear cells occurred, whereas in the noninfected allogeneic BMTx recipients, the septal width was on the order of 2 microns (P < 0.01). Treatment with DHPG (20 mg/kg in two daily doses for 5 days) resulted in a decrease in virus titers (log10 PFU per gram of tissue) in lungs and spleens from 3.81 +/- 0.34 and 4.29 +/- 1.07 (untreated animals) to 1.26 +/- 0.53 and 3.22 +/- 0.27 (treated animals), respectively. Treatment with HPMPC (20 mg/kg as a single dose) resulted in a complete reduction of virus titers in all organs to below the detection level (P < 0.01). Furthermore, antiviral treatment resulted in a reduction of the alveolar septal width from 6.02 +/- 1.59 microns (untreated animals) to 4.67 +/- 1.70 and 3.32 +/- 0.63 microns after DHPG and HPMPC treatment, respectively. Treatment with HPMPC (20 mg/kg as a single dose) resulted in a complete reduction of virus titers in all organs to below the detection level (P <0.01). Furthermore, antiviral treatment resulted in a reduction of the alveolar septal width from 6.02 +/- 1.59 micrometre (untreated animals) to 4.67 +/- 0.63 micrometre after DHPG and HPMPC treatment, respectively. Furthermore, the influx of mononuclear cells in the alveolar septa was significantly impaired after treatment with HPMPC (P <0.01). We conclude that in the described rat model, HPMPC is highly effective in suppressing RCMV-induced interstitial pneumonitis after allogeneic BMTx.

Animals

Cytomegalovirus IgM antibody detection: comparison of five assays.

Human Cytomegalovirus (CMV) infection can result in a dramatic disease in immunosuppressed patients. For effective treatment sensitive and specific procedures are required for prompt and early diagnosis of active CMV infection. In the present study five different serological assays were used for detection of CMV-specific immunoglobulin M antibodies (IgM) in 78 sera, obtained from patients with a clinical suspicion of CMV infection. In addition, sequential sera, obtained from renal transplant recipients who experienced a primary CMV infection, were analysed by the five IgM detection assays. The assays used were two enzyme-linked immunosorbent assays (ELISA): the Vironostika CMV ELISA from Organon Teknika (ELISA-1) and the Monosan CMV ELISA from Sanbio (ELISA-2), the CMV microparticle enzyme immunoassay (MEIA) from Abbott and two Western-(immuno)blotting techniques using purified CMV structural viral proteins of the AD169 strain (IB-AD169) and the major non structural DNA binding protein of 52 kiloDalton (IB-Rp52) as antigenic material. The results of the assays were compared to each other with respect to sensitivity, specificity and overall agreement, as well as incidence of false positive and false negative results. Although the MEIA gave the highest sensitivity, the ELISA-1 combined a high sensitivity with a high specificity and therefore appears the most suitable method for determination of active CMV infection.

Adolescent

[A child with Chlamydia trachomatis pneumonia].

A six week old boy is presented with a Chlamydia trachomatis pneumonia. This pneumonia is seldom diagnosed because of the mild clinical symptoms and the good prognosis, even without therapy. Diagnosing the Chlamydia trachomatis infection of the neonate is of importance for the mother and the child. Chlamydia trachomatis infections in neonates are an underestimated problem.

Chlamydia Infections

Comparative activity of (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine and 9-(1,3-dihydroxy-2-propoxymethyl)guanine against rat cytomegalovirus infection in vitro and in vivo.

Two antiviral compounds, (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine [HPMPC] and 9-(1,3-dihydroxy-2-propoxymethyl)guanine [DHPG], were evaluated for their inhibitory effects on human cytomegalovirus (HCMV) replication in human embryonal fibroblasts and on rat cytomegalovirus (RCMV) replication in rat embryonal fibroblasts. The concentrations of HPMPC or DHPG required to inhibit HCMV plaque formation by 50% were 0.1 and 0.6 micrograms/ml, respectively. For RCMV, these values were 1.1 and 25 micrograms/ml, respectively. For HCMV, the selectivity indices of HPMPC and DHPG, as determined by the ratio of the 50% inhibitory concentration for cell growth to the 50% inhibitory concentration for virus plaque formation, were 1,250 and 140, respectively, and for RCMV, they were 500 and 76, respectively. HPMPC was far more active than DHPG against RCMV infection in vivo as measured by mortality, histopathological changes, and virus titers in organs of immunocompromised RCMV-infected rats. The minimal effective dosage required to prevent mortality from RCMV infection was a single dose of HPMPC at 2 mg/kg of body weight compared with DHPG therapy twice daily at 20 mg/kg/day for 5 days. Furthermore, HPMPC was more effective than DHPG in reducing virus titers in internal organs (P less than 0.01) and in RCMV-induced histopathologic lesions. In contrast to DHPG, which did not show activity when administered 1 day before infection, HPMPC was effective even when administered 7 days before RCMV infection.

Animals

An animal model for therapeutic intervention studies of CMV infection in the immunocompromised host.

An experimental rat model to study acute cytomegalovirus infections is described. Eight-week old male Brown Norway rats, immunosuppressed by total body irradiation, were infected with rat cytomegalovirus (RCMV). The effects of infection were determined by survival rates and the presence of virus or viral components in different organs was assayed by plaque test, immunoperoxidase staining, dot-blot DNA hybridization and in situ DNA hybridization. At days 10-post infection nearly 90% of the animals had died. Spleen, liver and bone marrow were heavily infected. Interstitial pneumonia was observed. Pathological findings strongly resembled the full scale of lesions in human CMV infections. Anti-RCMV hyperimmune serum was effective against mortality from RCMV infection and viral spread to lungs and liver was prevented. This model is appropriate for studies on the pathogenesis and antiviral therapy of CMV infections in the immunocompromised host.

Animals