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Biomedical subjects

J Callahan

Publications and source records attributed to J Callahan.

At least 19 recordsLinked to original sources
PubMed2006

Atypical phenotype in a boy with a maple syrup urine disease.

Maple syrup urine disease (MSUD) is a metabolic disorder due to a block in the decarboxylation step in the catabolic pathways of the branched-chain amino acids (BCAAs). We describe an atypical presentation in an infant male. The patient presented with psychomotor retardation, profound hypotonia and elevated plasma levels of BCAAs, but no elevation of alloisoleucine. Cranial magnetic resonance imaging showed prominent diffuse CSF spaces, delayed myelin maturation and symmetrical signal abnormality within the globi pallidi, midbrain, dorsal pons and medulla. The cerebellar white matter was specifically spared. A mitochondrial disorder was suggested. After correction of feeding problems with G-tube feeds, his high BCAAs persisted and, on fourth analysis, alloisoleucine was seen. Subsequent fibroblast enzyme and mutation analysis confirmed MSUD due to E(1)-alpha subunit deficiency. After starting dietary treatment, there was no significant improvement in his hypotonia or his psychomotor development. However, the high signal within the globi pallidi had resolved. MSUD may have diverse clinical presentations, and should be considered in children who present with chronic psychomotor delay but no acute encephalopathic episodes. BCAA levels may not be very high, alloisoleucine may not always be detected in MSUD even with severe enzyme deficiency, and imaging may be misleading if seen in the chronic phase only.

Amino Acids, Branched-Chain↗
PubMed2001

Preparation of Fab' from murine IgG2a for thiol reactive conjugation.

Lysyl endopeptidase (LE) from Achromobacter lyticus M497-1 (EC 3.4.21.50) was utilized to prepare F(ab')2 fragments from mouse anti-P-glycoprotein IgG2a obtained from the UIC2 hybridoma. This report describes a novel single step purification procedure for F(ab')2 fragments that eliminates residual LE activity responsible for secondary cleavage of F(ab')2 to Fab fragments. The purification of F(ab')2 and Fc fragments was accomplished utilizing protein G affinity chromatography and either gradient or step changes in the pH/ionic strength for elution of the Fc and F(ab')2 fragments. Residual LE was eluted from the protein G column with buffer containing 200 mM L-lysine prior to elution of F(ab')2 and Fc fragments. The activity of LE was monitored using the fluorogenic substrate Boc-Val-Leu-Lys-7-amido 4-methyl coumarin. A similar purification procedure for F(ab')2 fragments produced following pepsin digestion of IgG2a is also outlined. The ability of Fab' fragments, from reduced F(ab')2 fragments following LE digestion of IgG2a, to conjugate to thiol reactive groups was demonstrated using N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-meso chlorin e6 mono (N-2-aminoethylamide) (Mce6) conjugates containing reactive maleimide groups. The biological activity of the Fab' targeted HPMA copolymer-Mce6 conjugates was tested against the P-glycoprotein expressing human ovarian carcinoma A2780/AD cell line utilizing a cell survival assay. Fab' targeted HPMA copolymer-Mce6 conjugate demonstrated significantly higher cytotoxicity than either a monoclonal antibody (mAb) targeted HPMA copolymer-Mce6 conjugate or a non-targeted HPMA copolymer-Mce6 conjugate, p < 0.05.

Animals↗
PubMed2000

Intracellular forms of human NOTCH1 interact at distinctly different levels with RBP-jkappa in human B and T cells.

The cellular transcriptional repressor RBP-Jkappa associates with the Epstein-Barr virus nuclear antigens (EBNAs) determined to be essential for transformation of human primary B lymphocytes. It was demonstrated through genetic analysis that interaction between the viral transactivator EBNA2 and RBP-Jkappa is essential for EBV immortalization of primary B lymphocytes. We have shown that the association of RBP-Jkappa with intracellular NOTCH1 differs significantly in B and T cells. Immunoprecipitation analyses with antibodies to both the intracellular forms of NOTCH1 and to RBP-Jkappa demonstrated that little or no RBP-Jkappa is associated with NOTCH1 in B cell lines compared to the RBP-Jkappa associated with NOTCH1 in T cell lines and was further demonstrated in human primary lymphocytes. Additionally, EBNA2 can compete with intracellular NOTCH1 for binding to GST-RBP-Jkappa in vitro. Northern blot for the cellular gene hairy enhancer of split (HES1) demonstrated that HES1 is upregulated in the EBV transformed lymphoblastoid cells expressing high levels of EBNA2 and in a T cell line SupT1 overexpressing intracellular activated NOTCH1. Hence, EBNA2 may be able to compete for the available pool of RBP-Jkappa more effectively in human B cells than in T cells and provides a possible explanation for the ability of EBV to potently and efficiently infect and immortalize human B cells. Leukemia (2000) 14, 84-92.

B-Lymphocytes↗
PubMed2000

Intracellular forms of human NOTCH1 functionally activate essential Epstein-Barr virus major latent promoters in the Burkitt's lymphoma BJAB cell line but repress these promoters in Jurkat cells.

We have demonstrated that intracellular forms of NOTCH1 transactivate two major Epstein-Barr virus (EBV) latent promoters, the LMP1 and Cp1 promoters in an EBV-negative B-cell line, BJAB. Truncated intracellular NOTCH1 associated with the nuclear membrane (DeltaE) transactivates the LMP1 promoter fivefold; however, the intranucleus localized form of NOTCH1 (ICN) transactivates this promoter approximately twofold in chloroamphenicol acetyltransferase (CAT) reporter assays in BJAB cells. Additionally, DeltaE activated the major Cp1 promoter 12-fold, whereas the ICN form of NOTCH1 activates at only about half that level when compared to that of DeltaE membrane-bound NOTCH1. This result differs from previously observed data, where intracellular NOTCH1 bound to the nuclear membrane, DeltaE, and nucleus-localized NOTCH1, ICN, all had similar levels of activation in 293 cells. This suggests distinct transcriptional activities in different cell types. Moreover, in Jurkat cells, a T-cell line, intranucleus localized NOTCH1 molecules demonstrated a repressive activity against the two EBV major latent promoters. Only DeltaE activated the Cp1 and LMP1 promoters at a level slightly above background, whereas intranucleus localized NOTCH1 ICN, or the form of NOTCH1 lacking the ankyrin repeats, DeltaE(TAR), surprisingly resulted in the repression of these promoters in Jurkat cells. Similarly, another truncated form of NOTCH1, referred to as ICNW, which contains the tryptophan residue W(1767) within one of the RBP-Jkappa interacting domains, repressed the LMP1 promoter approximately twofold. Further analysis of the truncated NOTCH1 molecules on the LMP1 promoter element, lacking the two RBP-Jkappa binding sites, suggests that repression in Jurkat cells may be affected by the presence of the two RBP-Jkappa binding sites. These studies indicate that intracellular NOTCH1 can activate the EBV major latent promoters in BJAB cells. However, in Jurkat cells, intracellular truncated forms of NOTCH1 lacking the RBP-Jkappa binding sites repress these EBV latent promoters. Only the membrane-bound form of NOTCH1, DeltaE, activated the EBV major latent promoters in Jurkat cells, albeit at a lower level than that seen in BJAB cells. Our data suggest that EBNA2 and truncated intracellular nuclear localized forms of NOTCH1 may be functionally similar in their interactions with RBP-Jkappa; however, these molecules may have distinctly different transcriptional partners in BJAB and Jurkat cells. Moreover, these truncated NOTCH1 molecules may not represent the normal processed forms of NOTCH1 in cells and may exhibit dominant negative phenotypes in the absence of the required posttranslational modifications. Further investigations are necessary to determine the similarity and differences occurring with intracellular NOTCH1 in other B- and T-cell lines.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Predictors and correlates of bereavement in suicide support group participants.

A sample of 210 survivors of suicide, all participants in suicide support groups, was studied. Associations between demographic factors, circumstances surrounding the suicide, and overall levels of grief (using the Grief Experience Questionnaire) were calculated. Results showed that seeing the body at the scene of the death was the most significant predictor of high levels of distress, and support from family and friends was the strongest protective factor. Time since the death (for women) and attendance at Alcoholics Anonymous meetings (for those participating in nonsuicide support groups) were also significantly related to level of grief. For men, a moderate level of participation in other support groups, as compared with none, was associated with higher levels of grief. All other variables were not significant. Results suggest that a model that combines posttraumatic reactions and grief is most appropriate for the aftermath of suicide.

Adult↗
PubMed1999

Distinct patterns of viral antigen expression in Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus coinfected body-cavity-based lymphoma cell lines: potential switches in latent gene expression due to coinfection.

Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV), also referred to as human herpesvirus 8 (HHV-8), are human gammaherpesviruses associated with numerous lymphomas and proliferative diseases in humans. We were interested in the protein expression patterns of specific latent and lytic proteins from the EBV genome in two body-cavity-based lymphoma cell lines, BC-1 and BC-2, which are coinfected with EBV and KSHV. BC-1 and BC-2 were analyzed using specific antibodies to latent proteins known to be essential for EBV immortalization of human primary B-lymphocytes in vitro and lytic antigens important for EBV replication and production of viral progeny. The coinfected cell lines are compared with two singly infected KSHV cell lines to determine whether antibodies against EBV-specific proteins cross-reacted against KSHV antigens. All the KSHV-infected cell lines express the KSHV-specific latency-associated nuclear antigen (LANA) with a specific pattern in the nucleus. This staining was distinct from that seen for EBNA1 in the EBV coinfected lines BC-1 and BC-2 staining the nucleus as a diffused pattern throughout the nucleus with denser staining in some regions. The coinfected cell lines all express EBNA1 and LMP1 at lower levels compared with singly infected EBV lymphoblastoid cell lines (LCLs). However, the essential latent antigens EBNA2, EBNA3A, and EBNA3C are not expressed in BC-1 and BC-2. This indicates potential regulation of EBV latent gene expression by KSHV-encoded viral or KSHV-induced cellular gene products. Additionally, lytic gene expression analysis demonstrated that BZLF1 and BMRF1 are expressed along with other early antigens (EA-D). A specific protein is detected in a singly infected KSHV cell line with cross-reactivity to antibodies that detected the EA-D complex. Moreover, in all the cell lines infected with EBV, KSHV, or EBV and KSHV, human serum with antibodies against KSHV antigens recognizes specific viral antigens approximately 110 and 41-42 kDa, suggesting that human antibodies against KSHV-specific antigens can cross-react with similar EBV antigens. Therefore these data suggest that the EBV pattern of gene expression in the coinfected cell lines is a type II pattern of latency also seen in other human tumors including nasopharyngeal carcinoma and Hodgkin's lymphoma. This distinct pattern of latent and lytic gene expression in these cell lines may provide clues as to the selection for coinfection in these body cavity based lymphomas in immunocompromised hosts.

Antigens, Viral↗
PubMed1998

Venezuelan equine encephalitis febrile cases among humans in the Peruvian Amazon River region.

A survey was conducted from October 1, 1993 to June 30, 1995 to determine the arboviral etiologies of febrile illnesses in the city of Iquitos in the Amazon River Basin of Peru. The study subjects were patients who were enrolled at medical care clinics or in their homes by Peruvian Ministry of Health (MOH) workers as part of the passive and active disease surveillance program of the MOH. The clinical criterion for enrollment was the diagnosis of a suspected viral-associated, acute, undifferentiated febrile illness of < or = 5 days duration. A total of 598 patients were enrolled in the study. Demographic information, medical history, clinical data, and blood samples were obtained from each patient. The more common clinical features were fever, headache, myalgia, arthralgia, retro-ocular pain, and chills. Sera were tested for virus by the newborn mouse and cell culture assays. Viral isolates were identified initially by immunofluorescence using polyclonal antibody. An ELISA using viral-specific monoclonal antibodies and nucleotide sequence analysis were used to determine the specific variety of the viruses. In addition, thin and thick blood smears were observed for malaria parasites. Venezuelan equine encephalitis (VEE) virus subtype I, variety ID virus was isolated from 10 cases, including three cases in October, November, and December 1993, five cases in January and February 1994, and two cases in June 1995. The ELISA for IgM and IgG antibody indicated that VEE virus was the cause of an additional four confirmed and four presumptive cases, including five from January through March 1994 and three in August 1994. Sixteen cases were positive for malaria. The 18 cases of VEE occurred among military recruits (n = 7), agriculture workers (n = 3), students (n = 3), and general laborers (n = 5). These data indicated that an enzootic strain of VEE virus was the cause of at least 3% (18 of 598) of the cases of febrile illnesses studied in the city of Iquitos in the Amazon Basin region of Peru.

Adolescent↗
PubMed1998

High prevalence of hantavirus infection in Indian communities of the Paraguayan and Argentinean Gran Chaco.

Serologic evidence of past infection with a Sin Nombre-like hantavirus(es) was demonstrated in 78 (40.4%) of 193 Indians living in western Paraguay and in 38 (17.1%) of 222 Indians inhabiting the Salta province of northern Argentina. In both populations seroprevalence increased with age, with the most striking increase occurring at 18 years of age in the Paraguayan population and at 35 years of age in the Salta population. The peak prevalences in both populations (66.6% and 44.0%, respectively) were seen in Indians > 53 years old. Although no sex difference was observed in the Paraguayan Indians, in the Salta population seroprevalence was greater in males than in females. Familiar clustering of the infection was observed. The data indicate that the Indian populations of the Gran Chaco are frequently exposed to and survive infection with a Sin Nombre-like virus(es). Possible explanations of this novel epidemiology are discussed.

Adolescent↗
PubMed1997

Venezuelan equine encephalitis and Oropouche virus infections among Peruvian army troops in the Amazon region of Peru.

An outbreak of a febrile illness characterized by headache, ocular pain, myalgia, and arthralgia occurred during June 1994 among Peruvian army troops in Northern Peru. On June 14-16, 1994, clinical data and blood samples were obtained from eight soldiers with a febrile illness, and from 26 others who had a history of febrile illness during the past three months. A follow-up blood sample was obtained 107 days later from four of the febrile and seven of the afebrile soldiers. Serum samples were tested for dengue (DEN), Oropouche (ORO), and Venezuelan equine encephalitis (VEE) IgM and IgG antibodies by an enzyme-linked immunosorbent assay (ELISA). Virus isolation was performed by inoculation of newborn mice and Vero cell cultures. Viral isolates were identified by immunofluorescence, ELISA, and nucleotide sequencing. A VEE virus infection was confirmed in three of the eight febrile soldiers, two by virus isolation, and one by serology. Antigenic analysis indicated that one of the virus isolates was similar to VEE subtype I, variety ID, viruses previously isolated in Colombia and Venezuela. Nucleotide sequence data showed that both viral isolates were identical to one another and closely related to VEE ID viruses previously isolated in Peru, Colombia, and Venezuela. Serologic results showed that two of 26 afebrile soldiers had IgM antibody to VEE and four had IgG antibody to VEE; two febrile soldiers had IgG antibody in their first serum samples. Oropouche-specific IgM antibody was detected in one of the eight febrile and five of the afebrile soldiers, and 18 of the 34 soldiers had low titers of ORO IgG antibody titers, which did not meet the diagnostic criteria for confirmed cases. All soldiers were negative for DEN IgM antibody, and 10 had flavivirus IgG antibody that reacted with DEN antigens. These data indicated that VEE ID virus was one of the causes of illness among Peruvians soldiers and that this was the first association of this VEE subtype with human disease in Peru.

Adolescent↗
PubMed1996

Bone marrow involvement and obstructive jaundice in Farber lipogranulomatosis: clinical and autopsy report of a new case.

We report a case of Farber lipogranulomatosis in a girl with hepatosplenomegaly, macular cherry-red spot, and subcutaneous nodules who developed liver dysfunction with jaundice and ascites, and myelophthisic anaemia because of infiltration of bone marrow with storage cells. Acid ceramidase assay confirmed the diagnosis. We conclude that the bone marrow dysfunction and cherry-red spot are features of type IV Farber lipogranulomatosis that have not been previously recognized, and should be added to the clinical phenotypic description.

Acid Ceramidase↗
PubMed1996

The fiberoptic intraparenchymal cerebral pressure monitor in 244 patients.

BACKGROUND: The fiberoptic intraparenchymal pressure monitor has been shown to provide reliable data in patients monitored for a short period of time. An analysis of a large population, including patients monitored for a prolonged period such as weeks, has never been performed. METHODS: We conducted a retrospective study in which we evaluated the fiberoptic intraparenchymal cerebral pressure monitor for complications and accuracy. RESULTS: The fiberoptic intraparenchymal cerebral pressure (ICP) monitor was used in 244 patients since 1988. Pathology included trauma in 180, intracerebral hemorrhage (ICH) in 19, aneurysmal subarachnoid hemorrhage in 16, arteriovenous malformations in 10, cerebral edema in 12, and tumor in 7. The mean length of monitoring was 7 days with 49 patients (20%) monitored 1-2 days, 105 (43%) monitored 3-6 days, 48 monitored for 7-10 days (20%), and 42 (17%) monitored from 10-24 days. Seventy-four patients also had ventriculostomies and there was strong correlation with the ICP monitor (p < 0.001). Complications from insertion were 2 patients (0.8%) with ICH, both with hepatic dysfunction. In the group monitored greater than 6 days, 34 patients (38%) required at least one catheter change due to upward drift of the ICP. Fiberoptic breakage requiring replacement was documented in 41 patients (16%). An insertion-site infection occurred in one case monitored for 23 days. Two infected bone flaps occurred that had a monitor placed in the flap. There were no cases of bacterial meningitis or cerebral abscess. CONCLUSIONS: The monitor is easy, safe, and reliable to use with a very low rate of infection. Coagulopathic patients may best be monitored by an alternative method.

Brain Edema↗
PubMed1996

The impact of a hospice consultation team on the care of veterans with advanced cancer.

To address the needs of patients with advanced cancer, all Veterans' Affairs hospitals were asked to establish teams of clinicians whose focus was to deliver expert palliative care. At the Philadelphia Veterans' Affairs Medical Center, our Hospice Consultation Team brought together professionals who had worked together informally in some of the outpatient oncology clinics. We conducted a prospective study of all consults received during the first year of the team's operation to determine whether or not the team approach would duplicate already available services or provide improved care. We identified 164 new medical/ nursing problems in 75 patients, 85% of which we were able to resolve. There were 152 new psychosocial/spiritual problems, but only 40%-61% were resolved. Of 22 patients followed in oncology clinics, new problems were identified and resolved in 21. We conclude that the expertise of the Hospice Consultation Team members along with the team process provided improved care to these patients.

Hospice Care↗