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Biomedical subjects

M Tadros

Publications and source records attributed to M Tadros.

12 recordsLinked to original sources
PubMed2006

A case of unusual substance abuse causing myeloneuropathy.

STUDY DESIGN: Case report. OBJECTIVES: Examine an unusual drug related case of myeloneuropathy as well as the pathophysiology of nitrous oxide induced subacute combined degeneration. SETTING: Major metropolitan teaching hospital - Princess Alexandra Hospital, Queensland, Australia. METHODS: Review case notes, investigations, relevant medical literature and epidemiological data. RESULTS: A 23-year-old female developed a myeloneuropathy and encephalopathy after an 8-month history of nitrous oxide abuse. Her presentation was complicated by acute renal failure, deep vein thrombosis (DVT) and pulmonary embolism (PE) as well as severe cognitive deficits. After eight months of multidisciplinary rehabilitation the patient is able to walk short distances with mobility aids and is able to manage self cares. However, she still requires a wheelchair for long distances and will have significant residual neurological deficits. CONCLUSION: The abuse of nitrous oxide has potentially serious outcomes that require discussion of issues related to harm minimisation and health promotion.

Adult↗
PubMed1999

The LHIalpha and LHIIalpha complexes in association with phospholipids are able to be inserted in heavy membranes of Rhodobacter capsulatus B10.

We show in this paper that a complex constituted by phospholipids and LHI and LHII alpha polypeptides was inserted in a heavy membrane fraction in a nonextractable form, indicating a transmembrane localization. The best accepting membranes originated from aerobically grown cells. Addition of ATP during the insertion inhibited this reaction 25 to 30% in heavy membranes isolated from aerobically grown cells (HMaer) and a higher inhibition (60 to 65%) was detected when using heavy membranes isolated from photosynthetically grown cells (HMpho). Purification by gel filtration of a crude Na2CO3 extract yielded three phosphate-labeled fractions. Two of them contained protein and phospholipids in a stable association. However, only fractions containing phosphatidylethanolamine were shown to be reconstituted. The third radioactive fraction contained labeled ATP and protein, but no phospholipids and could not be reassociated to the heavy membranes of any origin. A model for the insertion of the LH polypeptides is presented in which the recently synthesized polypeptides are phosphorylated and become associated to anionic phospholipids. The interaction of this complex to the membrane spontaneously leads to stable insertion.

Bacterial Proteins↗
PubMed1998

The phosphorylation of light-harvesting polypeptides LHIalpha (B870) and LHIIalpha (B800-850) of Rhodobacter capsulatus B10 was higher under chemotrophic oxic than under phototrophic anoxic growth conditions.

In Rhodobacter capsulatus B10 (wild type) both alpha subunits of the light-harvesting complexes are phosphorylated during photosynthetic membrane synthesis. During the process of insertion of these polypeptides, there is a dephosphorylation resulting in intracytoplasmic membranes in which no radioactive phosphate could be detected. Moreover, we show that their phosphate-specific contents depends on the growth conditions, the highest being observed under oxic conditions. When photosynthetic membrane synthesis was induced under light and anaerobiosis, a decrease in the phosphate-specific contents ensued. An inverse relationship exists between specific phosphorylation levels and the degree of membrane differentiation. The phosphorylation is thus a transient phenomenon characteristic of the photosynthetic membrane synthesis governed by the external redox conditions constituting an additional post-transcriptional level of regulation.

Autoradiography↗
PubMed1996

Purification and characterization of chaperonin 60 and heat-shock protein 70 from chromoplasts of Narcissus pseudonarcissus.

In chromoplast differentiation during flower formation in Narcissus pseudonarcissus, the molecular chaperones chaperonin 60 (Cpn60; alpha and beta) and heat-shock protein 70 (Hsp70) greatly increase in abundance. Both were purified and shown to be present in a functional form in chromoplasts, indicating their requirement in the extensive structural rearrangements during the chloroplast-to-chromoplast transition. The purified proteins, sequenced N terminally and from internal peptides, showed strong homology to plastid Cpn60 and Hsp 70 representatives from other plant species. During chromoplast differentiation, the carotenoid biosynthetic pathway is strongly induced. The corresponding enzymes are all nuclear encoded and form a large, soluble, hetero-oligomeric protein complex after import but prior to their membrane attachment. By immunoprecipitations we have shown that the plastid Hsp70 is a structural constituent of a soluble entity also containing phytoene desaturase.

Adenosine Triphosphatases↗
PubMed1994

Lack of IgA antineutrophil cytoplasmic antibodies in Henoch-Schönlein purpura and IgA nephropathy.

To verify whether IgA antineutrophil cytoplasmic antibody (ANCA) represents a serologic marker in Henoch-Schönlein purpura (HPS), we examined sera from 41 patients with the disease. Control sera from 28 patients with primary IgA nephropathy (IgA-N), 26 IgG-ANCA-positive vasculitis, and 28 normal controls were also studied. An increased IgA binding to neutrophil cytoplasmic extracts but not to purified ANCA antigens was found in 12.2-14.6% of HSP patients and in 14.3-21.4% of IgA-N patients versus 3.5% of normal controls. IgA binding to neutrophil cytoplasmic extracts correlated with serum IgA levels, IgA-rheumatoid factor, and IgA-fibronectin binding capacity. Moreover, low amounts of IgG and fibronectin were detected as contaminants in neutrophil cytoplasmic extracts and fibronectin could partly inhibit the binding of IgA to "crude" extracts. We conclude that IgA-ANCA are neither diagnostically nor immunologically specific in HSP and IgA-N. Several factors present in the sera of patients with IgA-related nephropathies seem to contribute to the "false-positive" IgA-ANCA demonstrable in these patients.

Adolescent↗
PubMed1993

Characterization of anti-myeloperoxidase antibodies in vasculitis.

Anti-myeloperoxidase (MPO) antibodies are frequently encountered in patients with vasculitis. Using a competitive inhibition ELISA test and immunoblotting, we suggest that anti-MPO antibodies might represent a heterogenous group of auto-antibodies directed against different conformational epitopes of MPO molecule.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1993

Rapidly progressive glomerulonephritis (RPGN): is there still an "idiopathic" subgroup?

In order to clarify if "idiopathic" RPGN still exists as a distinct entity we reviewed 41 patients with histological picture of diffuse crescentic GN (60% of crescents) and no clinical evidence of systemic disease. According to the presence or absence of intraglomerular necrotizing lesions we subdivided the patients into two different morphological groups: Group I (25 pts) with necrotizing GN and massive periglomerular infiltrates; Group II (16 pts) with intra-extracapillary proliferation and no interstitial infiltrates. Our data suggest that "idiopathic" RPGN does not exist as a distinct entity, but is an expression either of renal limited vasculitis or crescentic GN complicating primary proliferative GN.

Capillaries↗
PubMed1989

Gonadotropin-releasing hormone agonist inhibits physiologic ovarian follicular loss in rats.

To study the effect of long-term use of GnRH agonists on the number and size distribution of ovarian follicles, two experiments were performed on adult female rats. Treatment was continued for 52 days in Experiment 1 and for 229 days in Experiment 2. Every sixteenth section from one ovary of each rat was examined using a light microscope attached to a BioQuant image analysis computer system. In Experiment 3, control and previously treated rats were mated with known male breeders and the number and normalcy of the offspring evaluated. The results indicate that in rats treated with GnRH agonist: 1) the total number of follicles, the number and percentage of follicles less than 35 microns in diameter were significantly higher than in the control group: 2) the number and percentage of follicles greater than 50 microns in diameter were significantly lower than control: and 3) the number of rats that got pregnant and the litter size were not significantly different from control. We conclude that GnRH agonists inhibit the physiologic process of follicle recruitment and loss and that fertility is preserved after long-treatment administration of GnRH agonists.

Animals↗
PubMed1983

Importance of patient selection in local treatment of carcinoma of the rectum.

Fifty-eight patients with potentially curative adenocarcinomas of the rectum underwent fulguration of their tumors without regard to size of the lesion. The overall 5 year survival rate was 48.3 percent. However, if patients with adenocarcinomas that arose in villous adenomas were excluded, the 5 year survival rate dropped to 31.7 percent. Of the six patients with a carcinoma less than 3 cm in diameter, the 5 year survival rate was 83 percent. Of the 30 patients with lesions 3 cm or larger, the 5 year survival rate was 23.3 percent. No patient with a lesion larger than 4 cm was cured. It is believed that patients with small adenocarcinomas (less than 3 cm) have a better chance of cure with fulguration than with radical surgery. Cancers between 3 and 4 cm may be treated successfully by local means. Fulguration of rectal carcinomas should not be performed in patients with lesions larger than 4 cm in diameter, except for palliation or in those who refuse permanent colostomy.

Adenocarcinoma↗