HIV-Related pulmonary hypertension: analytic review of 131 cases

OBJECTIVE

To report two new cases of HIV-related pulmonary hypertension and to review and analyze the existing reports on the subject.

METHOD

Two new cases of HIV-related pulmonary hypertension are described, and the cases, case series, and related articles on the subject in all languages were identified through a comprehensive MEDLINE search.

RESULTS

Among the 131 reviewed cases, 54% were male, and the age range was 2 to 56 years (mean, 33 years). The interval between the diagnosis of HIV disease and the diagnosis of pulmonary hypertension was 33 months. In 82% of cases, pulmonary hypertension was related solely to HIV infection. Presenting symptoms were progressive shortness of breath (85%), pedal edema (30%), nonproductive cough (19%), fatigue (13%), syncope or near-syncope (12%), and chest pain (7%). The mean (+/- SD) pulmonary arterial systolic BP was 67 +/- 18 mm Hg (n = 116), and diastolic BP was 40+/-11 mm Hg (n = 39). Pulmonary vascular resistance was 983+/-420 dyne. s. cm(-5) (n = 29). Chest radiographs demonstrated cardiomegaly (72%) and pulmonary artery prominence (71%). Right ventricular hypertrophy was the most common electrocardiographic finding (67%). Dilatation of the right heart chambers was the most common echocardiographic finding (98%). Plexogenic pulmonary arteriopathy was the most common histopathology (78%). Pulmonary function tests demonstrated mild restrictive patterns with variably reduced diffusing capacities. The responses to vasodilator agents and antiretroviral therapy was variable. Sixty-six patients died during a median follow-up period of 8 months. The median length of time from diagnosis to death was 6 months.

CONCLUSION

HIV infection is an independent risk factor for the development of pulmonary hypertension. The appearance of unexplained cardiopulmonary symptoms in HIV-infected individuals should suggest pulmonary hypertension.

Antigiardial activity of isoflavones from Dalbergia frutescens bark

Several isoflavones [formononetin (1), castanin (5), odoratin (6), glycitein (7), pseudobaptogenin (8), fujikinetin (9), and cuneatin (10)] were isolated from Dalbergia frutescens, and their antiprotozoal activities were determined against Giardia intestinalis. Among these compounds, formononetin (1) was the most potent antigiardial agent, with an IC(50) value of 30 ng/mL (approximately 0.1 microM), as compared to the value for metronidazole, the current drug of choice, of 100 ng/mL (approximately 0.6 microM). Three isoflavones closely related to formononetin [daidzein (2), biochanin A (3) and genistein (4)] were also evaluated, but they were at least 100 times less active than 1. Formononetin (1) may thus be an interesting lead for development of new antigiardial agents or as a probe for a new mechanistic target.

Acute myocardial infarction with angiographically normal coronary arteries

The exact etiology of myocardial infarction remains unknown in a majority of the patients with normal coronary arteries. Those who smoke cigarettes and use cocaine are more prone to have this condition. The possible mechanisms underlying myocardial infarction with normal coronary arteries are hypercoagulable states, coronary embolism, an imbalance between oxygen demand and supply, nonatherosclerotic coronary diseases, coronary trauma, coronary vasospasm, and coronary thrombosis. Myocardial infarction with normal coronary arteries primarily affects younger persons and is distinctly rare in patients older than 50 years. We describe a case of acute myocardial infarction with normal coronary arteries in a 61-year-old woman who smoked cigarettes. The clinical perspectives and management of the myocardial infarction with normal coronary arteries are discussed.

Stenotrophomonas maltophilia endocarditis of prosthetic aortic valve: report of a case and review of literature

Stenotrophomonas Maltophilia (previously known as Xanthomonas maltophilia and Pseudomonas maltophilia ) is an aerobic, nonfermenting, gram-negative bacillus, which has emerged as a serious nosocomial pathogen in patients with compromised immunity. It is a rare cause of endocarditis with only 20 cases previously reported in medical literature. The risk factors associated with S maltophilia endocarditis include intravenous drug abuse, dental treatment, previous cardiac surgery, and infected intravascular devices. S maltophilia is resistant to multiple antibiotics, which leads to frequent therapeutic failures. Although the optimal antibiotic treatment for S maltophilia endocarditis remains unknown, most of the patients received 2 or more antibiotics. We report a case of S maltophilia endocarditis of prosthetic aortic valve, associated with a painless aortic dissection, that responded well to a combination of ciprofloxacin and chloramphenicol. The literature is reviewed to elaborate the disease characteristics, the treatments used, and the prognosis of the S maltophilia endocarditis.

Specificity of cardiac troponin I and creatine kinase-MB isoenzyme in asymptomatic long-term hemodialysis patients and effect of hemodialysis on these cardiac markers

OBJECTIVES

The objectives of this study were: (1) to evaluate the specificity of cardiac troponin I and creatine kinase-MB isoenzyme in ambulatory asymptomatic chronic renal failure patients on long-term hemodialysis, and (2) to evaluate the effect of hemodialysis on the serum levels of cardiac troponin I and creatine kinase-MB isoenzyme.

METHODS

One hundred and forty-four consecutive ambulatory asymptomatic chronic renal failure patients on hemodialysis for a minimum of 1 year were evaluated clinically. Serum cardiac troponin I and creatine kinase-MB isoenzyme levels were measured with specific monoclonal antibodies before and after dialysis using ACCESS Troponin I and ACCESS CK-MB assays.

RESULTS

The specificity of serum cardiac troponin I was 83% with a cutoff level of 0.03 ng/ml, which is an expected level for healthy population, but it rose to 100% with a cutoff level of 0.15 ng/ml, which is a reference level for patients with acute myocardial infarction. Twenty-four (17%) patients had borderline elevation in cardiac troponin I (>0.03 to <0.15 ng/ml). A history of angina pectoris was more common in the borderline-elevated cardiac troponin I subgroup. In 28% of the patients, serum creatine kinase-MB isoenzyme levels were increased with a specificity of 72% at a cutoff level of 4 ng/ml, which is the upper limit of normal, but the specificity rose to 98% by increasing the cutoff level value to 10 ng/ml. There were no statistically significant differences in serum levels of cardiac troponin I and creatine kinase-MB isoenzyme before and after dialysis.

CONCLUSIONS

Cardiac troponin I is highly specific in ambulatory asymptomatic chronic renal failure patients on long-term hemodialysis; borderline elevations in cardiac troponin I may represent microinjury to the myocardium. A serum level of creatine kinase-MB isoenzyme >2.5 times of the normal upper limit may be highly specific in this patient population. Hemodialysis per se does not significantly change the serum levels of cardiac troponin I and creatine kinase-MB isoenzyme.

Ambulatory blood pressure monitoring in children: a large center's experience

Ambulatory blood pressure monitoring (ABPM) is well established in adults and is becoming common in children. We reviewed 190 ABPM studies retrospectively (since 1990) to assess the failure rate, and analyzed the data from 97 patients 5-19 years old (1992-1996) to review the experience gained from the use of this technique in children and adolescents. Seventeen percent (32/190) of studies failed. Most children accepted ABPM, provided it was clearly explained in advance. There were differences between day and night readings of systolic blood pressure (BP), diastolic BP, and heart rate. BP did not correlate with height or weight. "White coat" effect apparently exists in children: clinic systolic BPs were higher than daytime systolic ABPM (no difference in diastolic). Eighty-nine percent (86/97) had an elevated BP load (>30% of readings >95th percentile). The antihypertensive medications of 16% (16/97) of patients were changed after ABPM. The nocturnal fall in BP (expressed as a percentage of the individual mean daytime values) was approximately normally distributed and was independent of age and height. Nocturnal systolic and diastolic dipping were closely correlated. Attenuation of nighttime dipping was observed in children with kidney disease and those with organ transplants. There is a need for normative data for ABPM for North American children. In our study, the technique was useful in selected cases, such as borderline or secondary hypertension, and for therapeutic monitoring when BP control is difficult.

Differential interaction of tubulin isotypes with the antimitotic compound IKP-104

The tubulin molecule is a heterodimer composed of two polypeptide chains, designated alpha and beta; both alpha and beta exist in numerous isotypic forms, which differ in their assembly and drug binding properties. 2-(4-Fluorophenyl)-1-(2-chloro-3, 5-dimethoxyphenyl)-3-methyl-6-phenyl-4(1H)-pyridinone (IKP-104) is an antimitotic compound which inhibits polymerization and induces depolymerization of microtubules [Mizuhashi, F., et al. (1992) Jpn. J. Cancer Res. 83, 211]. Since the previous work was undertaken with isotypically unfractionated tubulin, we have investigated the interactions of IKP-104 with the isotypically purified tubulin dimers (alpha beta(II), alpha beta(III), and alpha beta(IV)). We find that IKP-104 binds to alpha beta(II) and alpha beta(III) at two classes of binding sites. However, affinities for each class of site are much weaker for alpha beta(III) than for alpha beta(II). Interestingly, the low-affinity site on alpha beta(IV) was not detectable. Its high-affinity site was weaker than those of either alpha beta(II) or alpha beta(III). In a pattern consistent with these results, IKP-104 inhibited assembly better with alpha beta(II) than with the other two dimers. Higher concentrations of IKP-104 induced formation of spiral aggregates from alpha beta(II) and alpha beta(III) but not from alpha beta(IV). Our results suggest that the interaction of IKP-104 with tubulin isotypes is very complex: alpha beta(II) and alpha beta(III) differ quantitatively in their interaction with IKP-104, and alpha beta(IV)'s interaction differs both quantitatively and qualitatively from those of the other two dimers.

Lead and Aroclor 1254 disrupt reproductive neuroendocrine function in Atlantic croaker

We have previously shown that lead (lead chloride) and a polychlorinated biphenyl (PCB) mixture (Aroclor 1254) can alter hypothalamic serotonin (5-hydroxytryptamine, 5-HT) content, and pituitary gonadotropin II (GTH II) release in vitro, in the Atlantic croaker (Micropogonias undulatus). In the present study we investigated whether impairment of the hypothalamic 5-HT pathway involves alterations in tryptophan hydroxylase (TPH), the rate-limiting enzyme in 5-HT biosynthesis, or monoamine oxidase (MAO), the catabolic enzyme. Aroclor 1254 (1 mg/kg body wt. for 30 days) significantly inhibited hypothalamic TPH activity without altering MAO activity, and caused a significant decline in 5-HT content. On the other hand, lead exposure (15 mg/kg body wt. for 30 days) only induced a slight decrease in hypothalamic 5-HT content and TPH activity, and a minor increase in MAO activity. However, both Aroclor 1254 and lead significantly inhibited the GTH II response to stimulation by a luteinizing hormone-releasing hormone analog (LHRHa) in vivo and caused reduced gonadal growth. These results demonstrate that impairment of hypothalamic serotonin metabolism by Aroclor 1254 involves inhibition of 5-HT synthesis, whereas lead does not exert a profound influence on 5-HT metabolism. The decline in 5-HT availability due to reduced 5-HT synthesis in the PCB-exposed fish may result in disruption of the stimulatory 5-HT-GnRH pathway controlling GTH II secretion leading to impairment of gonadal growth.

Macrophyllosaponin E: a novel compound from the roots of Astragalus. oleifolius

Macrophyllosaponin E, a novel cycloartane-type triterpene, has been isolated from the roots of Astragalus oleifolius. The structure elucidation of the compound was achieved by a combination of one- and two-dimensional NMR techniques [1H-1H-correlation spectroscopy (COSY), 1H-13C-heteronuclear multiple guantum correlation spectroscopy (HMQC), and 1H-13C-heteronuclear multiple-bond correlation spectroscopy (HMBC)l and high resolution electrospray ionization Fourier transformation mass spectrometry (HR-ESI-FT-MS).

Nonatherosclerotic aneurysm of the left circumflex coronary artery presenting with accelerated angina pectoris: response to medical management--a case report

Coronary artery aneurysm is defined as coronary dilatation with a diameter of more than 1.5 times the adjacent normal coronary artery. Most of the coronary aneurysms remain asymptomatic. More than 90% of coronary aneurysms are of atherosclerotic origin. Nonatherosclerotic coronary aneurysms are rare, and the majority of them are diffuse. Among the three major coronary arteries, the left circumflex artery is the least commonly involved. The management strategies for nonatherosclerotic coronary aneurysms are not clear, and each case should be managed on an individual basis depending on the clinical context. Here described is a case of a discrete nonatherosclerotic aneurysm of the left circumflex coronary artery in a 46-year-old man who presented with accelerated angina pectoris and was treated medically. The patient was free of symptoms on 2-year follow-up. The clinical perspectives of the nonatherosclerotic coronary aneurysm are discussed.

Determination of parthenolide in selected feverfew products by liquid chromatography

The migraine prophylactic herb feverfew (Tanacetum parthenium L.) is marketed in the United States in a variety of forms and compositions. Although its therapeutic efficacy is still uncertain, the sesquiterpene lactone parthenolide is the constituent recommended to be measured for quality control of feverfew preparations. A validated liquid chromatographic method was developed and used to estimate parthenolide in a number of U.S. feverfew market products formulated as capsules, tablets, or crude powder. The method uses a Lichrosphere 5 C18 column, a mobile phase consisting of 50 mM NaH2PO4 in H2O (solvent A), and CH3CN-MeOH (90 + 10, v/v; solvent B). Elution was run at a flow rate of 1.0 mL/min with a linear gradient of 50-15% A in B over 20 min and UV detection at 210 nm. The correlation coefficient for the calibration curve was 0.9999 over the range of 0.00-0.400 mg/mL. Overall recovery of parthenolide was 103.1%.

Immunostimulatory effects of cycloartane-type triterpene glycosides from astragalus species

In the course of our research on the oligoglycosidic constituents of Turkish Astragalus species, we have isolated a number of cycloartane-type triterpene glycosides. The current study examines the immunostimulatory effects of nineteen of these cycloartane-type compounds using a transcription-based bioassay for Nuclear Factor kappa B (NF-kappaB) activation in a human macrophage/monocyte cell line, THP-1. All compounds were inactive at 100 microg/ml except astragaloside I which increased NF-kappaB directed luciferase expression to levels about 65% as compared with maximal stimulation by E. coli lipopolysaccharide (LPS) at 10 microg/ml. None of the compounds were active at low dosage levels (0.1 microg/ml) in combination with 50 ng/ml LPS. Astragaloside I also increased mRNA expression of the inflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) as measured using reverse transcriptase-polymerase chain reaction (RT)-PCR. Based on these results it is clear that certain structural features are required for immunostimulation of cycloartane-type triterpene glycosides.

Pharmacokinetics of ketoprofen enantiomers after intravenous administration of racemate in camels: effect of gender

The pharmacokinetics of ketoprofen (KP) enantiomers were studied in ten female and eight male camels after a single intravenous dose (2.0 mg/kg) of racemic KP. A high performance liquid chromatographic (HPLC) method was developed for the quantitation of the R- and S-enantiomers without derivatization of the samples using a S,S-Whelk-01 chiral stationary phase column. The data collected (median and range) were as follows: the areas under the curve to infinity (AUC) (microg/mL per h) were 22.4 (13.5-29.7) and 19.8 (13.8-22.1) for R- and S-KP, respectively, in female camels while the corresponding values in male camels were 16.0 (12.9-22.4) and 14.4 (11.0-19.3). In both sexes, the AUC for the R-enantiomer was significantly larger than that of the S-enantiomer. Total body clearances (Cl(t)) were 44.6 (33.7-74.1) and 50.6 (45.2-72.4) mL/kg per h for R- and S-KP, respectively, in female camels and were 62.8 (44.6-77.8) and 69.6 (51.8-91.1) mL/kg per h for R- and S-KP, respectively, in male camels. In both sexes of camels, the Cl(t) values for R-KP were significantly lower than its corresponding antipode. The steady-state volumes of distribution (Vss) were 97.9 (82.8-147.2) and 102.0 (90.1-169.0) mL/kg for R- and S-KP, respectively, in female camels and were significantly different from each other, while the respective values in male camels were 151.5 (105.3-222.3) and 154.0 (114.7-229.0) mL/kg but were not significantly different from each other. The volumes of distribution (area) followed a similar pattern, where the values for R- and S-KP in female camels were 118.5 (95.6-195.2) and 137.6 (115.8-236.2) mL/kg, respectively, and the respective values in male camels were 215.6 (119.1-270.1) and 229.1 (143.3-277.4) mL/kg. The elimination half-lives (t1/2beta) were 1.88 (1.42-2.34) h and 1.83 (1.67-2.26) h for R- and S-KP, respectively, in female camels and were significantly different from each other, while the corresponding values in male camels were 2.11 (1.50-4.20) and 2.33 (1.52-3.83) h for R and S-KP, respectively, but were not significantly different from each other. The mean residence time followed a similar pattern. All pharmacokinetic parameters for R- and S-KP in female camels were significantly different from their corresponding values in male camels. The extent of protein binding for R- and S-KP was evaluated in vitro by ultrafiltration. The extents of protein binding for R- and S-KP were not significantly different from each other when each enantiomer was supplemented separately. However, when the enantiomers were supplemented together, protein binding of R-KP was significantly higher than that of S-KP in female but not in male camels.

IP-10 is critical for effector T cell trafficking and host survival in Toxoplasma gondii infection

The generation of an adaptive immune response against intracellular pathogens requires the recruitment of effector T cells to sites of infection. Here we show that the chemokine IP-10, a specific chemoattractant for activated T cells, controls this process in mice naturally infected with Toxoplasma gondii. Neutralization of IP-10 in infected mice inhibited the massive influx of T cells into tissues and impaired antigen-specific T cell effector functions. This resulted in >1000-fold increase in tissue parasite burden and a marked increase in mortality compared to control antibody-treated mice. These observations suggest that IP-10 may play a broader role in the localization and function of effector T cells at sites of Th1 inflammation.

A left atrial paraganglioma patient presenting with compressive dysphagia

Paragangliomas are rare neoplasms of neural crest origin arising in the chromaffin (pheochromocytoma) and chemoreceptor (chemodectoma) tissues. Only a few cases of paragangliomas have been reported in the heart. Most of the cardiac paragangliomas are located in, or adjacent to, the left atrium. The biological activity indicative of catecholamine production has rarely been shown in cardiac paragangliomas. Patients with cardiac paragangliomas may present with hypertension, or with various obstructive or compressive symptoms, depending on the location of the tumour. A left atrial paraganglioma compressing the esophagus causing dysphagia is presented. A 37-year-old female patient underwent work-up for dysphagia to solids. Transesophageal echocardiography showed the presence of a large mass in the dilated left atrium. The tumour was removed completely intact and was a benign noncatecholamine-secreting paraganglioma. The patient's dysphagia was relieved. The clinical perspectives of cardiac paraganglioma and cardiac dysphagia are discussed.

Cimiracemoside a: A new cyclolanostanol xyloside from the rhizome of Cimicifuga racemosa

A new 9,19-cyclolanostane-type triterpene xyloside (1), from the rhizomes of Cimicifuga racemosa, has been isolated together with four known saponins; cimiaceroside A, 25-O-methylcimigenol-3-O-beta-D-xylopyranoside, 27-deoxyactein and 23-O-acetylshengmanol-3-O-beta-D-xylopyranoside. The structure of the new compound was established as 16beta,23:22beta,25-diepoxy-12-acetoxy-3beta,23,24b eta-trihydroxy-9,19-cyclolanost-7-ene-3-O-beta-D-xylopyranoside . For the structure elucidation, 1D- and 2D-NMR experiments and high resolution electrospray ionization Fourier transformation mass spectrometry (HRESIFTMS) were used.

Failure of short-course ceftriaxone chemotherapy for multidrug-resistant typhoid fever in children: a randomized controlled trial in Pakistan

The precise duration of therapy of multidrug-resistant (MDR) typhoid with broad-spectrum cephalosporins is uncertain. We prospectively randomized 57 children with culture-proven MDR typhoid to receive treatment with intravenous ceftriaxone (CRO) (65 mg/kg of body weight/day) for 7 days (short course; n = 29) or 14 days (conventional; n = 28). The response to therapy, as evaluated by the serial monitoring of the typhoid morbidity score and bacteriological clearance, was comparable between groups. In contrast to the conventional therapy, 14% of the children receiving CRO for 7 days had a confirmed bacteriological relapse within 4 weeks of stopping therapy.

The comparative effects of drive and test stimulus intensity on myocardial excitability and vulnerability

The number and intensity of stimuli that set basic cycle length in cardiac electrophysiological studies can influence the electrical properties assessed by extrastimuli. The relative contribution of drive (S1) and test (S2) stimulus intensity in defining myocardial excitability and vulnerability has not been reported. The purpose of this investigation was to assess this interaction and to determine whether atrial and ventricular findings differed. The effects of S1 and S2 intensity on atrial and ventricular stimulus-intensity-refractory-period curves were determined in open-chest dogs: comparisons were made between curves with S1 intensity varied between diastolic threshold (DT) and 10 mA and S2 intensity maintained at DT and those with S1 intensity maintained at DT and S2 intensity varied between DT and 10 mA. S1-S1 was held constant and S1-S2 varied. The effects of different stimulation sites, cycle length, number of stimulations, and neural blockade were assessed. S1 intensity amplification shifted atrial stimulus-intensity-refractory period curves in the direction of increased excitability and vulnerability; the changes were more pronounced than those obtained by modulating S2 intensity. The changes produced by increasing S1 intensity were evident at different cycle lengths and were enhanced by an increased number of stimulations, but were not evident when S1 and S2 were delivered at different atrial sites. Although beta-blockade attenuated the effects of increasing S1 intensity somewhat, the addition of cholinergic blockade virtually abolished it. Ventricular refractoriness was also changed by modulation of S1 intensity, but the changes were less striking. In the atrium, modulation of S1 intensity has greater effects of stimulus-intensity-refractory-period relations than modulation of S2 intensity; in the ventricule, the converse is true.

Dose-intense paclitaxel, etoposide and cyclophosphamide: a safe and active regimen for tumor cytoreduction and stem cell mobilization in metastatic breast cancer

Patients with metastatic breast cancer in complete remission are the ones most likely to have an improved outcome with subsequent high-dose chemotherapy and autologous peripheral blood stem cell transplantation (HDC-PBSCT). Peripheral blood stem cells are usually procured following mobilization with single agent chemotherapy and colony-stimulating factor support. We utilized a dose-intense regimen of paclitaxel 200 mg/m2 i.v., etoposide 60 mg/kg i.v., and cyclophosphamide 3 g/m2 i.v. (TEC) followed by daily administration of granulocyte colony-stimulating factor. The aim was not only to mobilize stem cells but also to achieve optimal tumor cytoreduction prior to HDC/PBSCT. One hundred consecutive patients with metastatic breast cancer received 257 cycles of TEC between March 1994 and June 1997, with the aim of collecting 5 x 106 CD34-positive cells/kg usually following the second cycle of chemotherapy. Patient characteristics included a median age of 45 years, a median of two organ systems involved by disease, a median of two prior chemotherapy regimens and eight prior chemotherapy cycles, and a median interval of 8 months from diagnosis of metastases to first cycle of TEC. There were 61 febrile episodes during neutropenia and 13 of these were associated with bacteremia or fungemia. Mortality rate was 1%. An adequate number of stem cells was collected in 90% of patients. The overall response rate of the tumor was 58.8% with 23.7% complete responders among 97 evaluable patients. Multivariate analysis demonstrated chemosensitivity to the most recent standard chemotherapy regimen administered for metastatic disease, an ECOG performance score of 0 as opposed to 1, 2 or 3, and involvement by disease of only one organ system as significant variables for achieving a complete remission with TEC. This novel dose-intense regimen was safe and well tolerated, highly active against metastatic breast cancer, and capable of excellent stem cell mobilization. Bone Marrow Transplantation (2000) 25, 123-130.

2-Hydroxy-5-(ethanolamino)-3-(10'-Z-pentadecenyl)-1,4-benzoquinone, new microbial phase II metabolite of maesanin

The use of microbial models for biotransformation of the natural benzoquinone, maesanin (1), resulted in the isolation of an ethanolamine conjugate (5) from the culture broth of Debaryomyces polymorphus ATCC 20280. Metabolite 5 was characterized as 2-hydroxy-5-(ethanolamino)-3-(10'-Z-pentadecenyl)-1,4-benzoq uinone. The production of 5 represents a new type of phase II conjugation reaction in microbial systems. The results of preliminary mammalian metabolism of 1 in rats were inconclusive.

Painless limited dissection of the ascending aorta presenting with aortic valve regurgitation

Aortic dissection is a medical emergency carrying high morbidity and mortality. Prompt diagnosis is sometimes difficult because of its varying presentations, but it is critical to the achievement of good clinical outcomes. This report describes 2 cases of painless aortic dissection that presented with aortic valve regurgitation. In both, the dissection was limited to the ascending aorta just distal to the aortic valve. These dissections were diagnosed by transthoracic and transesophageal echocardiography.

Immune CD8(+) T cells prevent reactivation of Toxoplasma gondii infection in the immunocompromised host

Toxoplasma gondii remains a serious cause of morbidity and mortality in individuals that are immunosuppressed, patients with AIDS in particular. The cellular immune response, especially by gamma interferon (IFN-gamma)-producing CD8(+) T cells, is an essential component of protective immunity against the parasite. In the present study the role of CD8(+) T cells during the reactivation of Toxoplasma infection in an immunocompromised murine model was evaluated. Chronically infected mice were challenged with LP-BM5 virus, and the kinetics of CD8(+) T-cell function was studied. At 10 weeks after viral infection, mice showed obvious signs of systemic illness and began to die. At this stage, CD8(+) T cells were unresponsive to antigenic stimulation and unable to kill Toxoplasma-infected targets. IFN-gamma production by the CD8(+) T cells from dual-infected animals reached background levels, and a dramatic fall in the frequency of precursor cytotoxic T lymphocytes was observed. Histopathological analysis of the tissues demonstrated signs of disseminated toxoplasmosis as a result of reactivation of infection. However, treatment of the dual-infected animals with immune CD8(+) T cells at 5 weeks post-LP-BM5 challenge prevented the reactivation of toxoplasmosis, and mice continued to live. Our study for the first time demonstrates a therapeutic role for CD8(+) T cells against an opportunistic infection in an immunocompromised state.

IL-15 prolongs the duration of CD8+ T cell-mediated immunity in mice infected with a vaccine strain of Toxoplasma gondii

Immunization of mice with a vaccine (ts-4) strain of Toxoplasma gondii is known to induce complete protection against subsequent lethal infection. Ts-4-mediated protection has been reported to be primarily dependent on IFN-gamma-producing CD8+ T cells. However, duration of CD8+ T cell-mediated immunity in the ts-4-vaccinated animals is not known. In the present study, the kinetics of the CD8+ T cell response in mice immunized with the ts-4 strain of T. gondii was evaluated. Optimal CD8+ T cell immunity persisted at least 6 mo after vaccination, and mice at this time point continued to overcome lethal challenge with a more virulent strain. However, at 9 mo postimmunization, CD8+ T cell immunity was severely diminished and the mice succumbed to Toxoplasma challenge. Pretreatment of animals, vaccinated 9 mo earlier, with rIL-15 prevented the mortality induced by Toxoplasma challenge. The protective effect of IL-15 treatment was due to a rise in the frequency of Ag-specific CD8+ T cells. CD8+ T cells from IL-15-administered animals showed increased proliferation and IFN-gamma production in response to antigenic restimulation. These findings suggest that rIL-15 can reverse the decline in the long-term CD8+ T cell immune response in mice immunized with vaccine strain of T. gondii.

Immunolocalization of IL-1beta and IL-6 in optic nerves of patients with AIDS

PURPOSE

Immunohistochemical procedures were employed to test the hypothesis that cytokines such as interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) are involved in AIDS-related optic neuropathy and to determine the primary cell types involved.

METHODS

Fixed sections of six human HIV-1 infected optic nerves were immunostained for the presence of IL-1beta and IL-6, using horseradish peroxidase and diaminobenzidine as markers.

RESULTS

IL-1beta and IL-6 were found in astrocytes, macrophages, microglia, and endothelial cells. The great majority of astrocytes demonstrated strong immunoreactivity.

CONCLUSION

Our findings support the premise that IL-1beta and IL-6 are significant pro-inflammatory mediators in AIDS-related optic neuropathy. This finding supports the theory that HIV infection stimulates the release of IL-1beta and IL-6 in astrocytes, macrophages, and endothelial cells in the optic nerve which ultimately leads to demyelination, astrogliosis, and neuronal destruction.