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M Joseph

Publications and source records attributed to M Joseph.

At least 37 records · Page 2Linked to original sources
PubMed1998

Characterizing alterations in the pulmonary surfactant system in a rat model of Pseudomonas aeruginosa pneumonia.

Bacterial pneumonia remains a significant cause of patient morbidity and mortality worldwide. Pulmonary surfactant serves to maintain homeostasis in the lung through the maintenance of alveolar stability and the regulation of the alveolar immune response. The purpose of this study was to characterize the lung injury and associated surfactant alterations in a rat model of acute Pseudomonas aeruginosa pneumonia. Pneumonia was induced in male Sprague-Dawley rats via intratracheal injection of 0.2 ml, phosphate-buffered saline (PBS) containing P. aeruginosa (6x10(8) colony-forming units x mL(-1)). Control animals received 0.2 mL sterile PBS. Twenty-four hours after inoculation, the pneumonia group (PN) exhibited clinical signs of pneumonia including deficits in gas exchange, leukopenia and elevated arterial lactate levels. Morphological assessment confirmed the presence of pneumonia with airspaces filled with polymorphonuclear cells. Lung homogenate analysis demonstrated evidence of bacterial colonization of pneumonic lung tissue. Lung compliance was also significantly lower in the PN group. Lung lavage analysis of PN rats revealed the pooled surfactant levels to be lower and the surfactant function reduced compared to control rats. Surfactant composition was also found to be altered in PN rats. These results demonstrate that in Pseudomonas aeruginosa pneumonia, the pulmonary surfactant system is both poorly functioning and reduced in quantity. These alterations may contribute to the lung dysfunction characteristic of this disorder.

Acute Disease↗
PubMed1998

Insight into the environment of tryptophan in a hydrophobic model peptide upon aggregation and interaction with lipid vesicles: a steady state and time resolved fluorescence study.

Fluorescence spectroscopy is extensively used to monitor binding of peptides to lipid vesicles as well as orientation in the lipid bilayer. In steady-state fluorescence, the emission characteristics of intrinsic and extrinsic fluorophores, which are sensitive to environment are monitored. Life time measurements should yield useful information about the location and flexibility of fluorophores, as these factors have a significant effect on the life times. However, studies on protein structure and dynamics indicate that interpretation of life-time data is complicated (Beechem. J.M. and Brand, L. (1985) Annu. Rev. Biochem. 54, 43-71). Hence, simple well-defined systems should help in interpretation of life time data, especially in lipid-peptide interactions. In order to examine how fluorescence characteristics of tryptophan and anthroyl group would reflect molecular details of peptide aggregation and lipid-peptide interaction, studies have been carried out on a model hydrophobic peptide and its fatty acylated derivative. Steady-state fluorescence measurements suggest that: (1) the fatty acyl chain attached to an amino acid associates with the peptide chain in aqueous environment. (2) In the lipid bilayer, the acyl chain is oriented perpendicular to the lipid bilayer surface with the peptide chain at an angle to it. Analysis of the fluorescence decay of tryptophan indicates the predominance of a very short life-time component (<1ns) in aqueous environment and lipid-vesicles. Since the preexponentials were not negative, it is unlikely that this is due to extensive deactivation process. We attribute the observation of the low life time component to predominance of one rotamer around (C alpha-C beta)bond of tryptophan in aqueous and lipid environments. Our investigations suggest that fluorescence life time data need to be complemented with steady state measurements to get an insight into details of lipid-peptide interaction.

Amino Acid Sequence↗
PubMed1997

Expression and functions of the high-affinity IgE receptor on human platelets and megakaryocyte precursors.

Platelets can be activated by IgE and are therefore involved in IgE-mediated effector mechanisms against parasites and in allergic disorders. Here we show that, besides the low-affinity IgE receptor (Fc epsilon RII/CD23), platelets express the high-affinity receptor for IgE (Fc epsilon RI). Flow cytometry analysis revealed the existence of surface Fc epsilon RI on platelets with a large heterogeneity among individual donors, and a low proportion of platelets co-expressing Fc epsilon RI and FC epsilon RII/CD23. Northern hybridization and reverse transcription polymerase chain reaction confirmed the presence of mRNA encoding the alpha, beta and gamma chains of Fc epsilon RI in platelets and in their megakaryocytic precursors. Cross-linking of Fc epsilon RI with monoclonal antibody (mAb) to alpha chain using either the whole molecule or F(ab')2 triggered platelet cytotoxicity for Schistosoma mansoni larvae. Anti-Fc epsilon RII/CD23 mAb significantly inhibited IgE- or Fc epsilon RI-mediated cytotoxicity, indicating down-regulatory effects of Fc epsilon RII/CD23 on Fc epsilon RI-dependent functions. These results demonstrate functional properties for Fc epsilon RI on platelets and indicate unsuspected interactions between the low- and the high-affinity IgE receptors.

Adult↗
PubMed1997

A new X linked recessive syndrome of mental retardation and mild dysmorphism maps to Xq28.

Efforts to understand the genetic basis of mental retardation are greatly assisted by the identification of families with multiple relatives with mental retardation that clinical geneticists encounter in the routine practice of their profession. Here we describe a linkage study of a four generation family in which X linked recessive mental retardation (XLMR) is associated with minor dysmorphism and premature death of the affected males. Microsatellite based polymorphic loci evenly spaced over the entire X chromosome were used initially to detect linkage to Xq28. Further analysis identified a haplotype of Xq28 markers bounded proximally by locus DXS1113 and distally by DXS1108 that cosegregated with XLMR in this family. Two point lod scores > 3.0 provided strong evidence that the gene locus responsible for XLMR in this family is within this 7 Mb region of Xq28. The minor anomalies noted in some affected males were not distinctive enough to suggest a unique syndrome. None of our patients had features of the Waisman-Laxova syndrome or the PPM-X syndrome. The possibility of allelism with any of the five other non-specific XLMR syndromes (MRX3, MRX16, MRX25, MRX28, and MRX41) mapped to Xq28 could not be excluded. While the recognition of a gene responsible for this disorder needs much additional work, multiple female relatives at risk in this family benefit immediately from knowing their genotype and heterozygotes will have the opportunity to undergo prenatal diagnosis.

Adult↗
PubMed1997

Alterations of the endogenous surfactant system in septic adult rats.

Sepsis is the most common factor leading to the acute respiratory distress syndrome (ARDS) and is associated with the highest mortality rate. It has been suggested that the pulmonary surfactant system is altered and contributes to the lung dysfunction associated with ARDS. The objective of this study was to characterize the lung injury, specifically the endogenous surfactant system in septic adult rats. Sepsis was induced in male Sprague-Dawley rats by cecal ligation and perforation and resulted in significant increases in heart rates, respiratory rates, and lactate levels along with positive blood cultures in septic animals compared with a sham control group. Two distinct septic groups were developed, a septic group and a sepsis with lung injury (septic+LI) group. The septic group had no significant differences in oxygenation compared with the sham group, whereas the septic+LI group had significantly lower PaO2 and higher A-a gradient values compared to both the sham and septic groups. The total surfactant pool size was significantly lower in the septic+LI group compared with the sham group. The small surfactant aggregate to large surfactant aggregate ratio was significantly lower in the septic group and was further reduced in the septic+LI group. There were also significantly higher levels of surfactant protein A (SP-A) in both septic and septic+LI groups compared to the sham group. These results demonstrated that the endogenous surfactant system was altered in systemic sepsis without lung dysfunction and is further altered when a lung injury is present.

Analysis of Variance↗
PubMed1996

Interactions between endothelial cells and effector cells in allergic inflammation.

The local inflammatory response that occurs after repeated exposure to allergens or during the late-phase reaction results from a complex network of interactions between inflammatory cells (mast cells, eosinophils, macrophages) and resident cells belonging to the lung structure itself like EC, fibroblasts, or bronchial epithelial cells. Among structural cells, EC represent critical elements: they control leukocyte traffic through the expression of adhesion molecules; they are also able to amplify leukocyte activation through the production of proinflammatory cytokines like IL-1, IL-6, or of chemokines like IL-8. Three cell models have been successively considered. When supernatants of alveolar macrophages, recovered from patients exhibiting a late asthmatic response after allergen exposure, were tested on HUVEC cultures, a TNF alpha-dependent ICAM-1 and E-selectin overexpression was observed. Among mast-cell mediators, histamine was already known to induce a rapid and transient expression of P-selectin; we demonstrated that histamine also induced an IL-6 and IL-8 secretion by HUVEC, which was concentration-dependent and inhibited by H1 or H2 receptor antagonists. Finally purified eosinophils obtained from donors with hypereosinophilia similarly increased adhesion molecule expression and chemokine production. The precise nature of the eosinophil product(s) involved in this process is currently under investigation.

Asthma↗
PubMed1996

Venom immunotherapy modulates interleukin-4 and interferon-gamma messenger RNA expression of peripheral T lymphocytes.

The mechanism by which specific immunotherapy exerts its beneficial effect remains unclear. In order to evaluate the influence of venom immunotherapy on the T-cell cytokine pattern of allergic reactions, we studied interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) mRNA expression of peripheral T lymphocytes from 12 patients undergoing rush venom desensitization, before treatment at Day 0 (D0), at Day 15 (D15) and Day 90 (D90) after treatment, and from seven controls. Antigen-specific T-cell proliferation was also determined. Cytokine mRNA expression was evaluated using in situ hybridization, 24 hr after culture of peripheral T cells with medium, venom, or an unrelated allergen. Allergen-induced T-cell proliferation decreased at D15 and D90 of rush immunotherapy (P < or = 0.02). In venom-stimulated cultures of the patient group, there was a decrease in IL-4 mRNA-positive cells at D15 and D90 (P < or = 0.001). Before desensitization, IFN-gamma mRNA expression was lower in patients than in controls and did not increase after in vitro allergen stimulation. In contrast, after immunotherapy, spontaneous IFN-gamma mRNA expression increased, but only at D90 (P < or = 0.001). The cytokine pattern observed at D90 after immunotherapy was similar to that observed in control subjects. In conclusion, venom immunotherapy induced an altered cytokine mRNA pattern in allergen-stimulated T cells which was dissociated from the early changes of allergen-induced T-cell responsiveness.

Adolescent↗
PubMed1996

Xp pseudoautosomal gene haploinsufficiency and linear growth deficiency in three girls with chromosome Xp22;Yq11 translocation.

Colony stimulating factor-2 receptor alpha (CSF2RA) and interleukin-3 receptor alpha (IL3RA), two genes from the chromosome Xp and Yp pseudoautosomal region (PAR), have been suggested as candidate genes for short stature in Turner syndrome. We report three girls with X;Y translocation (46,X,der(X)t(X;Y)(p22;q11) initially detected by amniocentesis. The terminal portion of the X chromosome distal to the translocation breakpoint at Xp22 was deleted on the derivative X chromosome in all three patients. Each had normal stature at birth, with greater than expected deceleration of growth velocity by the second year. Using fluorescence in situ hybridisation (FISH), we have shown deletion of the CSF2RA and IL3RA loci on the derivative X chromosomes of all three patients. The role of CSF2RA and IL3RA haploinsufficiency in linear growth and final adult stature is discussed. Additional studies, particularly of molecular deletions within the PAR, are needed to improve our understanding of the role of these and other PAR loci in the genetic control of adult stature.

Adolescent↗
PubMed1996

Timing of exogenous surfactant administration in a rabbit model of acute lung injury.

The purpose of this study was to evaluate early vs. late administration of exogenous surfactant in an adult rabbit model of acute lung injury. Lung injury was induced by repetitive whole lung saline lavage and subsequent mechanical ventilation. Bovine lipid extract surfactant was instilled either 1 (Early) or 4 h (Late) after the last lavage. Animals were monitored for 7 h after the last lavage. Although arterial PO2 values increased significantly immediately after treatment in both the Early and Late groups, this improvement was not sustained in the Late group. There was also a higher incidence of pneumothoraxes in the Late group vs. both the Early group and a nontreated control group. The ratio of poorly functioning small surfactant aggregates to superior functioning large aggregates was higher in the Late group compared with the Early group. Morphological analysis revealed that early surfactant treatment prevented the progression of lung injury over time. We conclude that administration of exogenous surfactant at an early time point in lung injury resulted in superior responses compared with later treatments.

Animals↗
PubMed1996

Acylation of proteins: recent advances.

The biochemistry and cell biology of covalent attachment of the fatty acids palmitic and myristic to proteins has been the subject of extensive investigations during the past fifteen years. While the site of attachment of fatty acids and the primary structure of proteins around the acylation site have been extensively documented, the exact role of the fatty acids have only been speculated upon. Since fatty acids would prefer to be associated with the lipid bilayer of membranes, it has been assumed that the role of the fatty acid is to provide a stable membrane anchor. This review discusses recent reports in the area of fatty acylation which suggests roles for the fatty acid other than that of a stable membrane anchor.

Acylation↗
PubMed1995

X-linked myotubular myopathy: clinical observations in ten additional cases.

X-linked myotubular myopathy (XLMTM) is a recessively inherited disorder, lethal to males in the first months of life. Since the first report in 1969, at least 90 cases have been described in the literature. Diagnosis is confirmed by muscle biopsy. Linkage studies have localized the disorder to the Xq28 region, close to the loci for X-linked hydrocephalus and MASA syndrome. We report on 10 additional cases of XLMTM from six different families. In addition to classic clinical features of XLMTM, our patients showed interesting associated findings which included birth length > 90th centile and large head circumference with or without hydrocephalus in 70%, narrow, elongated face in 80%, and slender, long digits in 60% of cases. There was concordance in the occurrence and severity of hydrocephalus in most sib pairs. These features in a "floppy" male infant serve as clues for early clinical diagnosis of XLMTM, which can then be confirmed by muscle biopsy. Development of polyhydramnios was observed in the third trimester of an at-risk dizygotic twin gestation monitored by serial sonography with confirmation of XLMTM at birth.

Birth Weight↗
PubMed1995

Conformations of peptides corresponding to fatty acylation sites in proteins. A circular dichroism study.

Fatty acid acylation is a posttranslational modification found in membrane proteins that have hydrophobic sequences serving as transmembrane segments as well as those that do not have them. The fatty acids myristate and palmitate are linked through an amide bond to N-terminal glycine and SH of cysteine via a thioester bond, respectively. In order to elucidate whether or how fatty acid acylation would modulate peptide structure, especially in hydrophobic environment, we have carried out circular dichroism studies on synthetic peptides both hydrophobic and hydrophilic in nature, corresponding to fatty acylation sites and their fatty acyl derivatives. The hydrophilic peptides were approximately 12 residues in length as studies on proteins modified by site-directed mutagenesis indicated that a peptide segment of approximately 12 residues is sufficient to direct acylation as well as membrane association, especially when the fatty acid is myristic acid. The peptide corresponding to a transmembrane segment composed of 31 residues as well as its palmitoyl derivative was found to adopt alpha-helical structure. Acylation appeared to favor increased partitioning into miscelles even in the case of a hydrophobic peptide. The hydrophilic peptides and their myristoyl or palmitoyl derivatives showed very little ordered structure in micelles. Our results suggest that the myristoyl and the palmitoyl moieties do not have the ability to "force" a hydrophilic peptide segment into a hydrophobic micellar environment. Thus, the mere presence of a fatty acid moiety may not be sufficient for membrane binding and recycling as is assumed especially in proteins in which no hydrophobic segment is present.

Acylation↗
PubMed1995

Interaction of peptides corresponding to fatty acylation sites in proteins with model membranes.

In recent years, a large number of proteins having covalently linked myristic and palmitic acids have been discovered. It is assumed that fatty acid acylation serves to anchor proteins to membranes. However, it is not clear whether fatty acids modulate orientation of peptide chain in membranes or help in associating hydrophilic segments of peptides with membranes. We have examined the aggregation properties and membrane association of peptides corresponding to myristoylation and palmitoylation regions of proteins by fluorescence spectroscopy. Both acylated and non-acylated peptides were used for investigation. Binding of the peptides to lipid vesicles was assessed by monitoring the fluorescence of tryptophan as well as the quenching of its fluorescence in the presence of quenchers like I- and acrylamide. Our results indicate that in the peptide corresponding to a transmembrane segment, palmitoylation results in a change in the orientation of the peptide chain in the lipid bilayer. In the case of peptides that do not have a hydrophobic segment, acylation with palmitic or myristic acid does not appear to result in increased binding to lipid bilayer. Our results suggest that (i) the primary role of myristoylation may not be an anchor for membrane attachment as assumed, (ii) palmitoylation in the case of proteins having transmembrane segments may serve to realign the transmembrane segment from the normal orientation perpendicular to the bilayer surface, (iii) in the case of proteins where there is no hydrophobic segment, palmitoylation may not serve as a membrane anchor and could be involved in interaction with other membrane-bound proteins.

Acylation↗
PubMed1995

Risk of human immunodeficiency virus type 1-related neurologic disease in a cohort of intravenous drug users.

BACKGROUND: Although the proportion of cases of acquired immunodeficiency syndrome related to intravenous drug use has increased dramatically over the past decade, there has been no longitudinal examination of primary neurologic disease in this group. OBJECTIVE: To study the development of neurologic disease in human immunodeficiency virus (HIV)-negative and HIV-positive men and women who were intravenous drug users over a 3.5-year period. DESIGN: Prospective observational cohort study. SETTING: Subjects were recruited from an infectious disease clinic at a New York City Hospital or from a methadone maintenance program. PARTICIPANTS: Ninety-nine HIV-negative (62 men and 37 women) and 124 HIV-positive (85 men and 39 women) intravenous drug users volunteered. MAIN OUTCOME MEASURE: The development of clinically significant manifestations in six neurologic domains. RESULTS: With multivariate adjustment for current and past substance abuse, age, education, and head injury, we examined the odds of developing HIV-related neurologic disease. Extrapyramidal signs and reduced motor ability became increasingly apparent over time in HIV-infected men as their CD4 cell count declined and as the subjects developed the acquired immunodeficiency syndrome. Fewer neurologic signs were seen in the women. CONCLUSIONS: The impact of HIV infection among intravenous drug users parallels that in homosexual men and is independent of alcohol and other drug use.

Adult↗
PubMed1995

Allergen-stimulated T lymphocytes from allergic patients induce vascular cell adhesion molecule-1 (VCAM-1) expression and IL-6 production by endothelial cells.

Adhesion of inflammatory cells to endothelium is a critical step for their transvascular migration to inflammatory sites. To evaluate the relationship between T lymphocytes (TL) and vascular endothelium, supernatants from allergen-stimulated TL obtained from patients sensitive to Dermatophagoides pteronyssinus (Dpt) versus healthy subjects were added to endothelial cell (EC) cultures. TL were stimulated by autologous-activated antigen-presenting cells (APC) previously fixed in paraformaldehyde to prevent monokine secretion. Two parameters were measured: the expression of adhesion molecule and the production of IL-6. Related allergen-stimulated TL supernatants from allergic patients induced an increase of VCAM-1 and intercellular adhesion molecule-1 (ICAM-1) expression when supernatants of the control groups (TL exposed to an unrelated allergen or not stimulated or TL obtained from healthy subjects) did not. E-selectin expression was not modulated whatever the supernatant added to EC culture. IL-6 production by EC was significantly enhanced after activation with related allergen-stimulated TL supernatants from allergics compared with control supernatants. Induction of VCAM-1 expression was inhibited by adding neutralizing antibodies against IL-4, whereas IL-6 production and ICAM-1 expression were inhibited by anti-interferon-gamma (IFN-gamma) antibodies. Enhanced production of IL-4 and IFN-gamma was detected in related allergen-stimulated TL supernatants from allergic subjects compared with the different supernatants. These data suggest that allergen-specific TL present in the peripheral blood of allergic patients are of Th1 and Th2 subtypes. Their stimulation in allergic patients may lead to the activation of endothelial cells and thereby participate in leucocyte recruitment towards the inflammatory site.

Adult↗
PubMed1995

Implications of gynaecological abnormalities in pre-selection criteria for cervical screening: preliminary evaluation of 3602 subjects in south India.

Early detection and eradication of cervical cancer and its precursor lesions through organized mass cytological screening programmes have recently gained considerable attention in developing countries. Strategies for both cost saving and effective implementation are however required for mass cervical screening in developing countries. In an early cancer detection programme conducted in South India, we analysed cytological abnormalities in 3602 women and correlated the results with other factors, including age, gynaecological complaints, number of years of married life and parity to see if pre-selection for cytologic screening was possible. Only lower grades of dysplasia were found in asymptomatic women below the age of 40 years. In asymptomatic women, malignancy and higher grades of dysplasia were confined to women with a clinically abnormal cervix only. Univariate analysis also revealed that subjects with a parity of more than 3 and a married life of more than 20 years had a significantly higher number of cytological abnormalities. However, on a multivariate analysis the increased number of marital years was not found to be an independent variable. These results suggest that asymptomatic women below the age of 40 years with a married life of less than 20 years and parity below 3, may be excluded from screening campaigns, and that pre-selection for cytologic screening is possible by introducing a programme of clinical and speculum examination of the cervix.

Adult↗