PubMed Health⌕ Search

Biomedical subjects

A London

Publications and source records attributed to A London.

At least 19 recordsLinked to original sources
PubMed1997

The effect of L-arginine on myocardial recovery after cardioplegic arrest and ischemia under moderate and deep hypothermia.

BACKGROUND: Depletion of L-arginine (L-arg), the substrate for nitric oxide (NO) synthesis, could be one of the mechanisms responsible for the reduced production of NO and decreased coronary flow (CF) during reperfusion. This, in turn, may adversely affect mechanical function. We aimed to study the benefits of exogenous administration of L-arg under conditions that mimick preservation of the heart for transplantation and routine cardiac surgery. METHODS AND RESULTS: Isolated working rat hearts perfused with oxygenated Krebs-Henseleit buffer were subjected to one of the two experimental protocols: (1) cardioplegic arrest with St Thomas' No 1 cardioplegic solution and 240 minutes of deep hypothermic (4 degrees C) ischemia, and (2) cardioplegic arrest with St Thomas' No 1 cardioplegic solution and 60 minutes of moderate hypothermic (20 degrees C) ischemia. In each protocol, hearts were divided into four groups (1 to 4 for protocol A and A through D for protocol B; n=6 in each group). In groups 1 and A (controls), hearts were arrested with the St Thomas' No 1 and were reperfused with standard Krebs-Henseleit buffer. In groups 2 and B, L-arg was added to cardioplegic fluid; in groups 3 and C, L-arg was added to reperfusate; and in groups 4 and D, L-arg was added to both cardioplegic fluid and reperfusate. Cardiac output, dP/dt, CF, and NO concentrations in the coronary effluent were evaluated in all groups before and after ischemia. After 4 degrees C ischemia (protocol A), the postischemic recovery of dP/dt for the control hearts in group 1 was 51.0+/-3.4%, which increased significantly to 73.3+/-2.7% and 70.1+/-4.4% in groups 3 and 4, respectively. In group 2, recovery of dP/dt was similar to the control group's and was 56.5+/-4.5%. Increased postischemic cardiac output and CF and increased production of NO correlated with improved functional recovery. After 20 degrees C ischemia (protocol B), the postischemic recovery of dP/dt was 47.2+/-3.5% in control group A and significantly increased to 79.2+/-2.6% in group B, to 82.0+/-3.5 in group C, and to 83.9+/-3.3 in group D. Increased postischemic CF and increased production of NO were closely related to improvement in mechanical function. CONCLUSIONS: Exogenous L-arg considerably improves the postischemic recovery of cardiac mechanical function and CF after cardioplegic arrest and ischemia by stimulation of NO production when given in the reperfusate after both 4 degrees C and 20 degrees C ischemia. However, L-arg as an additive to cardioplegia was only beneficial after 20 degrees C, and not after 4 degrees C ischemia.

Animals↗
PubMed1992

Interstitial deletion of 10q: clinical features and literature review.

We report on a patient with interstitial deletion of 10q and compare her to 8 previously described patients, 2 of whom have chromosomal breakpoints similar to our patient. Minor anomalies including broad forehead, hypertelorism, strabismus, prominent philtrum, and "dysplastic" pinnae are present in our patient. Psychomotor retardation and hypotonia are universal findings in 10q interstitial deletion. Growth retardation, not present in our patient, is seen in some. These clinical findings are sufficiently distinct to suggest early chromosome studies.

Chromosome Aberrations↗
PubMed1992

Palatal extension of middle meatal antrostomy.

The palatine bone is an important posterior landmark in the performance of ethmoidectomy. This usually unrecognized structure forms the posterior one third of the lateral nasal wall. Resection of a portion of the palatine bone completes the marsupialization of the sphenoethmoidal recess and medial maxilla. It is a major landmark for localization of the sphenopalatine artery at its entrance into the nose. Middle meatal antrostomy is enhanced by removal of the part of the palatine bone that forms the posterior medial wall of the maxillary sinus. In 1110 consecutive sphenoethmoidectomies, marsupialization of the maxillary sinuses has included partial removal of the perpendicular plate of the palatine bone. Patency has been maintained in all of these antrostomies. Pertinent anatomy and surgical technique are reviewed.

Humans↗
PubMed1991

Expression and secretion of staphylococcal nuclease in yeast: effects of amino-terminal sequences.

Staphylococcus aureus nuclease A hybrid genes, encoding proteins OmpA-nuclease, lipo-nuclease and Pin-nuclease, were cloned downstream of the yeast GAL10 inducible promoter. OmpA-nuclease and lipo-nuclease contain the mature staphylococcal nuclease sequence preceded by the Escherichia coli OmpA and lipoprotein signal sequences, respectively, whereas Pin-nuclease lacks a defined signal sequence at its amino terminus. We found that: (a) the nuclease gene products synthesized in yeast are active, but they do not affect cell growth; (b) OmpA-nuclease and lipo-nuclease are partially processed and constitute approximately 1.0-1.5% of the yeast cell protein; (c) OmpA and lipoprotein signal sequences function similarly in secretion, allowing 35-40% of the processed nuclease to be translocated into the yeast periplasm; and (d) Pin-nuclease, which lacks hydrophobic sequences at its amino-terminus, is accumulated at a level tenfold lower than the hybrid proteins that do contain signal sequences. Nevertheless, 50% of the enzyme activity of Pin-nuclease in yeast is localized in the periplasmic space.

Amino Acid Sequence↗
PubMed1990

Specific beta-lactam antibiotics inhibit secretion of lipo-beta-lactamase in yeast.

The beta-lactam antibiotic cloxacillin can inhibit secretion of prokaryotic lipo-beta-lactamase into the periplasm of yeast. The results indicate that this phenomenon is specific with respect to both the antibiotic and the lipo-beta-lactamase whose secretion is affected, strongly suggesting that this involves an interaction between the enzyme and its substrates. The effect of the antibiotic on secretion is reversible. With different beta-lactam antibiotics, the clearest difference is observed between type A and type S penicillins; the former exert a strong inhibition of secretion whereas the latter exhibit a weak effect or no effect at all. Type A penicillins have been previously shown to cause a conformational change in various beta-lactamases. Mature lipo-beta-lactamase species in yeast were localized either to the periplasmic space or bound to the outer surface of the cytoplasmic membrane and thus exposed to periplasm. The results are consistent with the hypothesis that binding of cloxacillin to lipo-beta-lactamase induces a conformation on the protein that is unfavourable for its release from the membrane.

Amino Acid Sequence↗
PubMed1981

Circulating immune complexes following food: delayed clearance in idiopathic glomerulonephritis.

Following a meal containing a variety of animal and vegetable proteins circulating immune complexes (CIC) have been found in sera from eight normal subjects. Levels of CIC rose to significantly higher levels in ten patients with idiopathic immune complex glomerulonephritis and return to fasting levels was significantly delayed. The type of CIC detected bore no relation to those in renal biopsy material. The CIC which accumulated in GN were small (MW similar to or approximately 350,000), and plasma exchange did not influence the extent or duration of CIC rise following the meal. An immunological defect manifested by impaired clearance of frequently encountered antigens may exist in subjects who develop GN. The CIC detected in the serum of these patients may be markers of this state and cannot be assumed to be the pathogenic agents in the disease.

Antigen-Antibody Complex↗
PubMed1980

The value of three immune complex assays in the management of systemic lupus erythematosus: an assessment of immune complex levels, size and immunochemical properties in relation to disease activity and manifestations.

Sixteen patients with systemic lupus erythematosus, fourteen with renal involvement have been studied over a 30-month period. Circulating immune complex levels have been assayed by three techniques. The results of tests on 141 sequential sera suggest that the three assays detected overlapping populations of the range of complexes present. Immune complex levels are shown to be good markers of disease activity and certain immunochemical properties of the complexes emerged as better markers than others. Immune complex size is a more important determinant of disease manifestation than are overall immune complex levels. High doses of intravenous methyl prednisolone, which did not reduce overall complex levels, reduced levels of those complexes (molecular weight 600,000-900,000 Daltons) associated with renal involvement.

Antibodies↗
PubMedDate not supplied

[Proceedings: Role of endogenous and exogenous ACTH on aldosterone secretion (author's transl)].

The role of ACTH in the control of aldosterone secretion has been investigated in volunteers under a normal sodium diet. Endogenous ACTH suppression by dexamethasone (DXM) does not alter the plasma aldosterone (PA) response to 20 mg furosemide since identical PA increases are observed in control subjects and in subjects with DXM suppressed endogenous ACTH. The sodium depletion induced by furosemide during continuous ACTH infusion increases plasma renin activity but does not change PA.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

[Effect of furosemide and ACTH on plasma renin, aldosterone and cortisol levels in normal man].

Plasma renin activity (PRA), aldosterone and cortisol's variations are studied in normal salt repleted voluntary men (120 mEq/24 h sodium) before and after furosemide infusion and/or constant infusion of ACTH (beta 1-24 corticotrophin). PRA is determined by angiotensin I radioimmunoassay, plasma aldosterone by specific radioimmunoassay and plasma cortisol by competitive transcortine binding radioassay. 1) PRA and plasma aldosterone increase clearly after acute sodium depletion secundary to furosemide infusion; plasma cortisol increases a little. PRA and aldosterone's variations are identical after endogenous ACTH suppression by dexamethazone administration before study. 2) PRA is not influenced by constant infusion (16 ng/kg/mn) after acute infusion (0.3 mg intravenously) of ACTH (beta 1-24); plasma aldosterone and plasma cortisol increase dramatically and remain constant along the experience. 3) If acute sodium depletion is realized 120 mn after ACTH infusion, PRA still raises; on the other hand plasma aldosterone remains constant. These results confirm that acute sodium depletion stimulates aldosterone secretion by the way of renin angiotensin system then ACTH acts directly on the adrenal cortex. Nevertheless the stimulative action of acute sodium depletion on aldosterone secretion is suppressed by previous acute ACTH stimulation.

Adrenocorticotropic Hormone↗