Balamuthia mandrillaris: its pathogenic potential.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
A J Martínez
Publications and source records attributed to A J Martínez.
Divergent effects of an alpha2-adrenergic antagonist on lipolysis and thermogenesis: interactions with a beta3-adrenergic agonist in rats.
This study was undertaken in order to test the hypothesis that selective beta3-AR stimulation and simultaneous blockade of alpha2-AR would result in an increase of lipolysis and thermogenesis in rats. Incubation of isolated white adipocytes with the alpha2-AR antagonist yohimbine produced a concentration-dependent increase in glycerol release (P<0.001) for all assayed concentrations (10-12-10-6 M) and potentiated the lipolytic effect of the beta3-AR agonist Trecadrine. However, in vivo administration of yohimbine produced a marked decrease in body temperature (1.3-1.5 degrees C, P<0.001) and blocked the thermogenic effect of Trecadrine when simultaneously administered. A similar response was observed for whole body oxygen consumption. Furthermore, yohimbine did not modify brown adipose tissue oxygen consumption, but blocked the beta3-AR-mediated increase triggered by Trecadrine. Brown adipose tissue UCP-2 and -3 mRNA expression was not changed by yohimbine. In conclusion, the present work indicates that in vitro alpha2-AR blockade by yohimbine potentiates the beta3-AR-mediated stimulation of lipolysis. On the other hand, in vivo alpha2-AR antagonism blocks the thermogenic effects mediated by beta3-AR stimulation, suggesting a possible interplay between the receptors.
Adipocytes↗
Mold occurrence and aflatoxin B(1) and fumonisin B(1) determination in corn samples in Venezuela.
Fumonisins are mycotoxins produced mainly by Fusarium moniliforme and Fusarium proliferatum, which have been associated with several animal and human diseases. Aflatoxins are hepatotoxic, mutagenic, and teratogenic metabolites produced by Aspergillus flavus and Aspergillus parasiticus. Both have been reported at high levels in corn. This study was pursued to determine mold, aflatoxin B(1) (AFTB(1)), and fumonisin B(1) (FB(1)) levels in white and yellow corn. Mold levels were determined using potato dextrose agar and identification of the main genus of molds present in corn, AFTB(1) levels by immunoaffinity chromatography, and FB(1) levels by a Bond-Elut SAX cartridge and HPLC. AFTB(1) an
Aflatoxin B1↗
Inhibition of peridural fibrosis after laminectomy using low-dose external beam radiation in a dog model.
OBJECTIVE: Clinical studies have demonstrated a significant association between the presence of extensive postlumbar discectomy peridural scar formation and the recurrence of low back and radicular pain. Low-dose perioperative radiation therapy has previously been demonstrated to inhibit peridural fibrosis after laminectomy in a rat model. The current study was designed to measure the effect of low-dose radiation on postlaminectomy peridural fibrosis development in a larger animal model. METHODS: Three dogs underwent a total of 12 lumbar hemilaminectomies. For each animal, two levels received 1) external beam radiation 24 hours before surgery, 2) surgery alone, or 3) radiation alone. Radiation was administered in a single fraction of 700 cGy using computed tomographic guidance for dosimetry planning. The isodose distribution was such that the dose conformed to the posterior epidural space with minimal exit dose to normal tissue. Port films were used to confirm the correct levels. Gadolinium-enhanced magnetic resonance imaging (MRI) of the lumbar spines was obtained before the animals were killed 12 weeks after surgery. The spines were harvested, and axial sections through the laminectomy defect were stained with hematoxylin and eosin and Masson's trichrome. All specimens were evaluated for extent of fibrosis along the dura, density of fibrosis, nerve root entrapment, and sublaminar fibrosis. RESULTS: There were no complications from the surgery, and no new neurological deficits were noted. There was a statistically significant difference between the irradiated and nonirradiated groups regarding the extent of fibrosis (P = 0.001) and the density of fibroblasts (P = 0.001). There was also a marked difference in nerve root entrapment (P = 0.182) and the presence of sublaminar fibrosis (P = 0.061) between the treatment and control groups. MRI revealed less gadolinium enhancement at the irradiated levels compared with the nonirradiated levels, confirming the usefulness of MRI in predicting the degree of epidural fibrosis. CONCLUSION: Low-dose external beam radiation therapy administered 24 hours before laminectomy in a dog model significantly decreased the extent and density of peridural fibrosis as well as nerve root entrapment and sublaminar fibrosis. This treatment strategy may be efficacious in patients with recurrent radicular pain after lumbar discectomy that is thought to be secondary to peridural fibrosis on the basis of gadolinium-enhanced MRI studies, and who might benefit from reoperation for nerve root decompression.
Animals↗
Immobilized biomolecules on plasma functionalized cellophane. I. Covalently attached alpha-chymotrypsin.
Surface morphology changes of hydrazine-RF-plasma-exposed cellophane surfaces were monitored under 40 kHz and 13.56 MHz CW and pulsed discharge environments and the immobilization of alpha-chymotrypsin onto plasma-modified substrates was studied. It has been shown, using SEM and AFM techniques, that significantly different cellophane topographies are generated under different frequency and pulsing parameter conditions. ESCA and ATR-FTIR analyses of plasma-modified surfaces indicated the presence of primary amide and primary amine functionalities. It was found that the relative ratios of crystalline vs amorphous zones of the nascent surface layers can also be controlled by properly selected plasma parameters, including the duty cycles of pulsed plasma environments. Enzyme immobilization reactions with alpha-chymotrypsin were accomplished both from oxygen-plasma-generated carbonyl and hydrazine-plasma-created primary amine functionalities by anchoring the biomolecules either directly to the cellophane surface or by involving spacer molecules. It was found with the cellulose substrates that fairly good enzyme activity was retained without the necessity of intercalated spacer chains. It appears that the ability of the cellulose substrate to swell in the aqueous environment allows sufficient freedom of mobility for the immobilized enzyme to retain a significant part of its activity on the cellulose. However, the activities both of the free enzyme in the presence of cellophane, and that of the immobilized enzyme molecules are significantly diminished in comparison to the activity of the free enzyme, as a result of the incorporation of these molecules into the swollen network. Potential applications of immobilized enzymes from cold-plasma-functionalized surfaces are discussed.
Argon↗
Inhibition of peridural fibrosis after laminectomy using low-dose external beam radiation in a rat model.
OBJECTIVE: Clinical studies have revealed a significant association between the presence of extensive postlumbar discectomy peridural scar formation and the reoccurrence of low back and radicular pain. Low-dose perioperative radiation therapy has been shown to inhibit scar formation. Its effect on peridural fibrosis, however, has not been studied. METHODS: Thirty male Sprague-Dawley rats underwent L5 laminectomies. Ten rats each received a single fraction of 700-cGy external beam radiation to the lumbar spine 24 hours before surgery; 10 rats each received 700 cGy 24 hours after surgery. The remaining 10 rats served as a control group. All of the rats were killed 30 days after surgery. The spines were harvested, and axial histological sections through the laminectomy defect were evaluated. Each specimen was scored for extent, density, and arachnoidal involvement by fibrosis. RESULTS: There was a statistically significant difference between the treatment and control groups regarding the extent of fibrosis along the dura (P < 0.001), the density of fibroblasts (P < 0.005), and the arachnoid involvement (P < 0.01). There was no difference in fibrosis reduction between the groups receiving pre- and postlaminectomy radiation. CONCLUSION: Low-dose external beam radiation therapy administered before or after laminectomy in a rat model significantly decreases the extent, density, and arachnoidal involvement of peridural fibrosis. This technique may improve the outcome of patients who undergo reoperations for recurrent radicular and/or low back pain after successful lumbar discectomy in whom there is a significant amount of peridural fibrosis.
Animals↗
The neuropathology of organ transplantation: comparison and contrast in 500 patients.
The main objective of this report is to compare and contrast the type and frequency of neuropathological findings following liver, heart, lung, heart-lung, kidney and bone marrow transplantation and to provide an overview of the major systemic complications in patients that received allografts. This is a retrospective analysis of the complete autopsy records and clinical histories of 500 adults who underwent organ transplantation at the University of Pittsburgh Medical Center during the interval of March, 1981 through July, 1997. This study is based on the neuropathological and systemic findings among 225 liver, 101 heart, 40 lung, 28 heart-lung, 74 kidney and 32 bone marrow transplants. Clinico-pathological correlations were made. All patients received base-line immunosuppressive therapy with one or more of the following drugs: cyclosporine, corticosteroids and azathioprine. Since August, 1989, the primary immunosuppressive agent is FK-506 (Tacrolimus). Some patients received antilymphocyte globulin (OKT3), when acute rejection was imminent. Light microscopic examination of tissue sections, stained with hematoxylin and eosin and in some cases with special stains were made. Ultrastructural evaluation were also performed in selected cases. All of the studies were carried out at the University of Pittsburgh Medical Center, Department of Pathology, Neuropathology Division. Cerebrovascular complications were the most frequent and were seen in 51% of the liver, 59% of the heart, 58% of the lung, 50% of the heart-lung, 49% of the kidney and 44% of the bone marrow allografts. Aspergillus sp. infection was the most common of all CNS infections followed by viral, bacterial and protozoal. Primary Central Nervous System Lymphoma (PCNSL) was seen in 2% of the liver, and 2% of the heart recipients. Post transplant lymphoproliferative disorder (PTLD) involving the brain was seen in 2% of the liver allografts, 3% of the heart, and 7% of the heart-lung recipients. PTLD systemically was seen in 6% of the liver, 7% of the heart, 5% of the lung, 11% of the heart-lung and 4% of the kidney allografts. Graft-versus-host disease was seen only in 41% of the bone marrow recipients. There was no statistically significant difference between the incidence of the total CNS complications among the different organ transplant groups (p value > 0.10), but there was a statistically significant difference in the systemic complications among the organ transplant groups (p value < 0.001). In conclusion that immunocompromised patients with impaired cellular and humoral immunity are at risk for the development of opportunistic infections and hematologic abnormalities. PTLD appears to be different in its pathogenesis from that of PCNSL which occurs anew in the brain of these patients. The neurological complications may be reduced by earlier recognition and better understanding of their etiopathogenesis.
Female↗
[Central nervous system infection by free-living amebas: report of 3 Venezuelan cases].
INTRODUCTION: Infection of the Central Nervous System by free living amebas is an unusual event, 344 cases have been reported to date. The disease becomes evident in two different clinical fashions: Primary Amebic Meningoencephalitis (PAM) caused by Naegleria fowleri and Granulomatous Amebic Encephalitis (GAE) induced by Spp. of Acanthamoeba and Balamuthia. CLINICAL CASES: The authors report three new cases from Venezuela. Case 1. 34 years old man, with a chief complaint of general malaise, headache and fever, a diagnosis of common cold was made and the patient was treated as such, he did not improve and was admitted to the hospital with deterioration of his clinical status; the patient died 10 days after the onset of his illness which was determined to be GAE produced by Balamuthia mandrillaris. Case 2. 8 years old female admitted to the hospital because of fever, headache and generalized seizures of sudden onset; neurocysticercosis was diagnosed and following improvement the patient was discharged and readmitted on two occasions because of relapse and worsening of her illness, she died 2 months after the onset of her disease that was diagnosed by autopsy as GAE due to Balamuthia mandrillaris. Case 3. 16 years old male, previously healthy, who following immersion in a water tank was admitted to the hospital because of meningeal irritation that progressed to coma and death in a 7 day lapse; autopsy revealed PAM by Naegleria fowleri. The two cases of GAE due to Balamuthia mandrillaris occurred in apparently immunocompetent individuals, contrary to the statement that these microorganisms are opportunistic. CONCLUSION: We believe that neurological infection by amphizoic amebas is being underdiagnosed, probably due to ignorance regarding this pathology or because of a very low autopsy rate in most countries.
Adolescent↗
Intracranial ependymomas of childhood. Lack of correlation of histopathology and clinical outcome.
The histopathology of 66 children with the diagnosis of ependymoma who were operated on at our institution between 1954 and 1994 were reviewed. We performed an initial analysis using the entire study cohort to determine which histopathological features associated with each other in a statistically significant fashion in an attempt to identify combinations of features that together might be useful in predicting outcome. A detailed outcome analysis was then performed on the 37 most recent cases who survived the postoperative period, in whom pre- and post-imaging studies as well as long term follow-up were obtained, in order to identify the histopathological features and combinations of features that were predictive of overall and progression-free survival. Five- and ten-year progression-free survivals were 45.1% and 36.1%, respectively. Overall survivals were 57.1% and 45.0%, respectively. Of the eight individual histopathological features, only the presence of necrosis was found to correlate with a less favorable overall and progression-free survival (PFS) (p = 0.06 and 0.03, respectively). In addition, the combination of necrosis with vascular proliferation or nuclear pleomorphism was associated with a worse PFS (p = 0.01 and 0.02, respectively). However, when other clinical predictive factors were included in a multivariate regression analysis, none of the histological features or combinations of features were independently associated with outcome. In addition, no relationship was found between the pattern of rosettes (true rosette, pseudorosette, or perivascular pseudorosette) and clinical outcome. In conclusion, although this study found an association between certain histopathological features and clinical outcome in children with ependymomas, these relationships did not reach statistical significance on multivariate analysis and, thus, do not provide sufficient evidence for modifying therapy based on histopathology alone.
Adolescent↗
Animal model Balamuthia mandrillaris CNS infection: contrast and comparison in immunodeficient and immunocompetent mice: a murine model of "granulomatous" amebic encephalitis.
Balamuthia mandrillaris and several species of Acanthamoeba are pathogenic "opportunistic" free-living amebas which cause granulomatous encephalitis (GAE) in humans and animals. The granulomatous component is negligible or absent, particularly in immunocompromised individuals. GAE is an "opportunistic" infection, usually seen in debilitated, malnourished individuals, in patients undergoing immunosuppressive therapy for organ transplants, and in Acquired Immunodeficiency Syndrome (AIDS). From around the world 156 cases of GAE have been reported from 1956 through October 1, 1995, 59 (26 in the USA) of them caused by B. mandrillaris, at least seven of them in AIDS patients. The present study was designed to compare and contrast the susceptibility of infection, the rate of infectivity and the histopathological changes within the CNS between the mutant, severe combined immunodeficient mice (SCID) infected with B. mandrillaris and the normal immunocompetent BALB-C mice. The SCID mouse is severely deficient in B and T lymphocytes, therefore lacking immunoglobulin and cell-mediated immunity. This mouse is also prone to develop early T cell lymphomas. One thousand amebic trophozoites and cysts of B. mandrillaris were intranasally and intraperitoneally inoculated in both strains in mice. Seventy percent of the intranasally inoculated SCID mice died due to CNS infection. Amebic trophozoites and cysts were found within CNS parenchyma without inflammatory response. Death occurred from 2 to 4 weeks after inoculation. By contrast only 10 percent of the intranasally inoculated BALB-C mice died with CNS infection showing the characteristic features of GAE. None of the intraperitoneally inoculated mice developed amebic infection. The SCID and BALB-C mice were logical models to study the structural alterations within the CNS of B. mandrillaris infection. This animal model recapitulates with excellent degree of fidelity several aspects of the pathogenesis and histopathological features of free-living amebic infection in human beings.
Amebiasis↗
Single-stage stereotactic diagnosis and radiosurgery: feasibility and cost implications.
We compared the efficacy and the hospital charges of either single-stage or two-stage stereotactic diagnosis and radiosurgery procedures. Twelve patients underwent either one-stage or two-stage diagnosis and management of their brain tumors. Both techniques utilize high-resolution intraoperative stereotactic image-guided technology and rapid touch preparation (imprint) cytopathological techniques to confirm the presence of neoplasm. Following this pathologic diagnosis, six patients immediately underwent stereotactic radiosurgery employing the same frame application and dose planning based on preoperative and intraoperative images. Six patients underwent two-stage procedures, i.e., discharge from the hospital after histopathological diagnosis followed by readmission, reapplication of the stereotactic head frame, and repeat neuroradiological imaging prior to radiosurgery. Requirements for success of the single-stage procedure include intraoperative stereotactic high-resolution imaging, a hospital-wide ethernet system for transferring neurodiagnostic images, and expertise in rapid touch-preparation histopathological technique for accurate diagnosis. Intraoperative computed tomography imaging after biopsy confirmed the target accuracy and lack of movement of the target after brain biopsy. The advantages of the single-stage approach include reduced length of overall hospital stay, simultaneous histopathological diagnosis and therapy in a single hospital admission, and reduced total hospital charges. For patients highly suspected of having brain tumors and for whom stereotactic radiosurgery will be utilized in the treatment, single-stage stereotactic diagnosis immediately followed by radiosurgery is an accurate, effective, and potentially less costly management strategy than a two-stage approach.
Adult↗
The neuropathology and epidemiology of AIDS. A Berlin experience. A review of 200 cases.
The brains of 200 patients who died with Acquired Immunodeficiency Syndrome (AIDS) from Berlin were examined retrospectively. This study was specifically intended to evaluate and document the prevalence of neuropathologic abnormalities, establishing the frequency of the various types of structural lesions, their combinations, their relative incidence, and the risk factors involved in different age groups. The data were compared and contrasted with the findings reported from other parts of the world and other German cities. It was found that the mean age of this group of patients was 41.4 years old, 75% were homosexual/bisexuals (H/B) and 18.5% were drug abusers (DA). Only 5.5% were women. Brain parenchymal changes, called in this report, HIV-related encephalopathy (HIVRE), characterized by vacuolization or spongy changes and astrocytosis in the subcortical white matter, and occasionally in gray matter, were found in 67 patients (33.5%). Drug abusers had a higher incidence of HIVRE (59.5%) compared with homosexual/bisexuals (28%). This is statistically significant (p < 0.0005). CMV encephalitis was found in 26 patients (13%) (8% of the drug abusers in contrast to 13% in the homosexual/bisexuals group). Primary central nervous system lymphoma (PCNSL) was seen in 28 patients (14%) regardless of the risk factor involved. 20 (13%) of the 150 H/B and 3 (8%) of the 37 DA had CMV encephalitis. Of the 150 H/B, 24 (16%) had PCNSL compared with only 4 of 37 (11%) of the DA. A significant incidence of opportunistic infections, both protozoal and viral was found in all groups. Cerebral toxoplasmosis occurred in 68 patients (34%). Microglial (phagocytic) nodules, probably related to CMV or cerebral Toxoplasmosis, were observed in 40 cases (20%). Diffuse microglial proliferation was noted in 104 patients (52%). Cerebral cryptococcosis was found in three patients. Progressive multifocal leukoencephalopathy was seen in 16 patients (8%). Various combinations of CNS pathological processes were found in 44 of the patients (22%). These include concomitant infections with Toxoplasma gondii and HIVRE in 13 patients; Toxoplasmosis and PCNSL in 8 patients; Toxoplasmosis with CMV and HIVRE in 4 patients; Toxoplasmosis with CMV in 2 patients; Toxoplasmosis with PCNSL and CMV in 2 patients; Toxoplasmosis with PCNSL and HIVRE in 2 patients and Toxoplasmosis with PML and HIVRE in 2 patients; Cerebral CMV with PCNSL and HIVRE in 4 patients; Cerebral CMV with HIVRE in 2 patients; PML with PCNSL in one patient; PML with HIVRE in 2 patients; and PML with PCNSL and HIVRE in one patient. Cerebrovascular lesions were found in 34 patients (17%).(ABSTRACT TRUNCATED AT 400 WORDS)
AIDS Dementia Complex↗
The neuropathology of South American mummies.
Few studies of intracranial mummified brain tissue have been undertaken. This is because of the infrequency in which preserved human central nervous system tissue is encountered and the scarcity of available mummies from different parts of the world. This study undertook a systematic analysis of 15 naturally mummified human brains from 1000 B.C. to 1500 A.D. excavated from the deserts of northern Chile. Gross examination revealed relatively well-preserved dura mater, cerebral hemispheres, cerebellum, and spinal cord in several cases. Five cases showed evidence of intracranial disease. Three cases had evidence of external injury. One case revealed subarachnoid and one case revealed intracerebral hemorrhage. Samples of central nervous system tissues were taken for further analysis. The samples were rehydrated and processed for structural analysis by light and electron microscopy. Light microscopy of the brain parenchyma revealed an eosinophilic staining background with vascular structures but few cellular elements present. The dura mater demonstrated normal dural architecture consisting of collagen fibrils. Electron microscopy did not clearly demonstrate individual neurons or axonal processes. Bundles of collagen fibrils with typical periodicity were clearly seen in the dura mater. The examination of ancient human central nervous system tissues reveals normal and abnormal neuroanatomy.
Axons↗
Acute effects of insulin-like growth factor-I (IGF-I) on bone protein synthesis in rats.
The acute systemic effects of IGF-I on bone protein metabolism from hormonally intact rats have been investigated by measuring the fractional rate of protein synthesis. The animals received a single subcutaneous injection of rhIGF-I (100 micrograms). Treatment with IGF-I increased the rate of tibia protein synthesis (Ks) while plasma glucose and insulin concentrations were decreased. These results are in favor of an endocrine role of IGF in stimulating bone growth.
Animals↗
Granulomatous amebic encephalitis: a review and report of a spontaneous case from Venezuela.
Granulomatous amebic encephalitis (GAE), or meningoencephalitis due to Acanthamoeba spp. and leptomyxid ameba are uncommon CNS infections that generally occur in immunocompromised hosts. We describe a case of GAE caused by Balamuthia mandrillaris previously designated as a leptomyxid ameba, in an apparently healthy 14-year-old Venezuelan boy. This case was characterized by sudden onset of seizures, focal neurologic signs and by a prolonged clinical course (from November 1992 to March 1993). Neuroimaging studies showed cerebral hypodense lesions in cerebral hemispheres, brain stem and cerebellum. Microscopically, we found a chronic granulomatous inflammatory reaction with necrotizing angiitis, large numbers of amebic trophozoites and few cysts in perivascular spaces and within necrotic CNS tissue. The amebas were identified as B. mandrillaris based on their immunofluorescence reactivity with the anti-B. mandrillaris serum. So far, 30 cases of GAE due to B. mandrillaris have been recognized in humans, two in AIDS patients. No visceral involvement by free-living amebas or any other significant abnormality was observed. This patient developed "spontaneous" GAE, but it remains possible that an undiagnosed abnormality in cell-mediated immunity or a deficient humoral immune response may explain the susceptibility of this patient to this opportunistic infection.
Adolescent↗
Selective embryo reduction in a sextuplet pregnancy.
The treatment course of a 29-year-old infertile woman using hMG and TDI was the cause of a sextuplet pregnancy in which a successful embryo reduction was carried out during the first trimester. The reduction was performed twice: the first around the 9th week of pregnancy transvaginally, and the second during the 12th week by transabdominal puncture. The perinatal outcome was favorable, and the patient spontaneously delivered a healthy infant on the 39th week of pregnancy.
Abortion, Therapeutic↗
Placental and fetal alterations due to Venezuelan equine encephalitis virus in rats.
Histopathological changes in the placentas, embryos, and fetuses of rats inoculated intraperitoneally with the virulent Guajira strain of Venezuelan equine encephalitis virus were studied by light microscopy and immunoperoxidase methods. Rats inoculated before day 15 of pregnancy showed necrosis and hemorrhages in the embryonic disks. Swelling of cytoplasm and nuclear pyknosis of cyto- and syncytotrophoblastic cells were noted as early as 2 days after inoculation. During weeks 1 and 2 of pregnancy, death of the embryos was always observed 3 to 4 days after Venezuelan equine encephalitis virus inoculation. Placental and fetal damage varied among the specimens. In rats 18 days pregnant and sacrificed 2 days after inoculation, there were some viable fetuses; the placentas showed inflammatory reactions in the mesometrial and decidual vessels. Other rats sacrificed at 3 to 4 days after inoculation showed large placental infarcts with fetal death. Viremia peaked during day 2 after inoculation. Immunoperoxidase stains demonstrated viral antigens present in the decidua, myometrium, and cyto- and syncytotrophoblastic cells. These experiments provide additional data regarding the pathogenesis and structural damage in the placental and fetal tissues caused by Venezuelan equine encephalitis virus.
Animals↗
Granulomatous amebic encephalitis presenting as a cerebral mass lesion.
Clinical and brain biopsy or autopsy findings in six patients with Granulomatous Amebic Encephalitis (GAE) due to acanthamoeba sp. were characterized by focal neurological symptoms, increased intracranial pressure, and focal neuroradiological findings. Craniotomies were performed because of the diagnostic possibility of a mass lesion such as a brain tumor or abscess. In four patients, frozen sections demonstrated free-living amebas. GAE may present as an acute or subacute intracerebral mass lesion with signs and symptoms of focal brain disease and should be differentiated from viral, bacterial, fungal, and other protozoal encephalitides.
Adult↗