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Biomedical subjects

C Lombard

Publications and source records attributed to C Lombard.

At least 19 recordsLinked to original sources
PubMed1992

Protein purification using combined streptavidin (or avidin)-Sepharose and thiopropyl-Sepharose affinity chromatography.

The major problem usually encountered in the application of the (strept)avidin-biotin system to the purification of proteins (or other biological molecules) lies in the difficult reversion of the interaction between immobilized (strept)avidin and the adsorbed biotinylated protein. Among the proposed solutions is the selective biotinylation of the entity to be purified by a disulphide-containing biotinylated reagent which allows its recovery from (strept)avidin gels by dithiothreitol (DTT) treatment. As emphasized by the example of angiotensin II receptor purification, achieved using this strategy, optimum reduction of this disulphide bridge may require improvement of its accessibility using denaturating agents such as sodium dodecyl sulphate or urea. However, these agents release important amounts of (strept)avidin. Two general ways of solving this problem are proposed. One solution takes advantage of the absence of cysteine in the streptavidin sequence: the protein to be purified is selectively readsorbed to thiopropyl-Sepharose through the thiol function generated on DTT cleavage of the biotinylated reagent. The other solution is an empirical approach to make possible the use of avidin, which possesses cysteine residues: combined avidin-Sepharose and thiopropyl-Sepharose chromatography proved efficient when carried out in the presence of urea as denaturing agent.

Animals↗
PubMed1992

The effect of morphine and naloxone administration on plasma oxytocin concentrations in the first stage of labour.

OBJECTIVE: We investigated the effect of an opiate (morphine) and an opiate antagonist (naloxone) on the maternal secretion of oxytocin in the first stage of labour. DESIGN: Patients were randomized to receive either morphine 5 mg (n = 9), naloxone 1.2 mg (n = 10) or sterile water (n = 9) which was injected intravenously. PATIENTS: Healthy women in the first stage of labour between 3 and 6 cm dilated with no prior analgesia or oxytocin administration were recruited for the study. MEASUREMENTS: Peripheral maternal oxytocin levels were measured by radioimmunoassay for 15 minutes before and 15 minutes after administration of the assigned substance. Sampling was at 2.5 minute intervals. RESULTS: Significant reduction in the mean oxytocin concentration was found in the patients who received morphine (-2.62 pmol/l/sample) but no change was found in the naloxone group (+0.57 pmol/l/sample) when compared with controls (+0.64 pmol/l/sample). CONCLUSION: Maternal oxytocin secretion is inhibited by exogenous opiates in the first stage of labour while an effect of opiate antagonism was not demonstrated.

Adult↗
PubMed1991

Plasma arginine vasopressin and the syndrome of inappropriate antidiuretic hormone secretion in tuberculous meningitis.

Biochemical evidence of the syndrome of inappropriate antidiuretic hormone secretion (SIADH) was documented in 17 of 24 (71%) children with tuberculous meningitis. Plasma arginine vasopressin concentrations in patients with signs of SIADH were significantly higher (median, 15.44 (range, 1.62 to greater than 24.52) pg/ml; n = 14) than those without (median, 1.91 (range, 0.44 to 4.91) pg/ml; n = 6) (P less than 0.002). Patients who developed evidence of SIADH were older than those who did not (median, 34 (range, 6 to 101) months vs. 10 (range, 6 to 38) months; P less than 0.007). Five patients with and none without died. In 9 patients evidence of SIADH developed only after hospitalization. These patients received a median of 58 (range, 28 to 109) ml/kg/day fluids (n = 7) before developing evidence of SIADH compared with 107 (range, 58 to 146) ml/kg/day received by patients who did not develop SIADH (n = 6) (P = 0.035). SIADH occurs commonly and its presence appears to influence the outcome of tuberculous meningitis in children.

Arginine Vasopressin↗
PubMed1991

Tetralogy of Fallot and segmental uterine aplasia in a three-year-old Morgan filly.

A 3-year-old Morgan filly was presented to the University of Florida, Veterinary Medical Teaching Hospital, for heart murmur, poor growth, and progressive exercise intolerance. Thoracic radiographs, cardiac ultrasound, cardiac catheterization, and differential blood gases were utilized to tentatively diagnose tetralogy of Fallot. Postmortem examination confirmed tetralogy of Fallot and additionally revealed segmental uterine aplasia.

Animals↗
PubMed1990

Affinity chromatography purification of angiotensin II receptor using photoactivable biotinylated probes.

We have developed biotinylated photoactivable probes that are suitable for covalent labeling of angiotensin II (AII) receptors and the subsequent purification of covalent complexes through immobilized avidin or streptavidin. One of these probes, biotin-NH(CH2)2SS(CH2)2CO-[Ala1,Phe(4N3)8]AII, which contains a cleavable disulfide bridge in its spacer arm and which displays, in its radioiodinated form, very high affinity for AII receptors (Kd approximately 1 nM), proved to be suitable for indirect affinity chromatography of rat liver receptor with facilitated recovery from avidin gels by use of reducing agents. This constituted the central step of an efficient partial purification scheme involving hydroxylapatite chromatography, streptavidin chromatography, and thiopropyl-Sepharose chromatography. SDS-PAGE analysis and autoradiography established the identity of the purified entity (molecular weight 65K) as the AII receptor. Possible ways of completing purification to homogeneity and extrapolation of the protocols to a preparative scale are discussed, as well as the potential contribution of our new probes to the study of the structural properties of angiotensin receptors.

Amino Acid Sequence↗
PubMed1990

Immunohistochemical and cytogenetic studies indicate that malignant angioendotheliomatosis is a primary intravascular (angiotropic) lymphoma.

The authors performed immunohistochemical and cytogenetic studies in a 73-year old man with malignant angioendotheliomatosis. The patient was referred for evaluation of fever of unknown origin, hepatic failure, and neurologic deterioration. Examination of a muscle biopsy revealed numerous, noncohesive atypical mononuclear cells within small vessels. These cells stained positively with a pan-leukocyte marker CD45(PD7/26/16) and with a B-cell marker L26 but negatively with Factor VIII-related antigen, an endothelial cell marker. Peripheral blood obtained before chemotherapy was cultured and analyzed by the G-band method. A new translocation and numerous chromosomal aberrations were identified. The major cell line karyotype was 53,XY, +X, +5q?,-6, +i(6p), +7, -10, +11, -12, +12p-, +12p-, +18, +mar1, +mar2, t(1;3)(p22;p21),3q+,8p+. This is the first cytogenetic study performed in a case of malignant angioendotheliomatosis. Our findings demonstrate that the neoplastic cells in this disorder circulate in the peripheral blood and provide further evidence that malignant angioendotheliomatosis is a diffuse intravascular neoplasm of lymphoid origin. Furthermore, the authors conclude that this malignant lymphoproliferative disorder should be reclassified as a primary intravascular (angiotropic) lymphoma.

Aged↗
PubMed1990

A clinicopathologic study of 34 cases of diffuse pulmonary hemorrhage with lung biopsy confirmation.

Based on a clinicopathologic study of 34 patients with biopsy-confirmed diffuse pulmonary hemorrhage (DPH), we present an approach to the differential diagnosis of DPH with attention to histologic features such as capillaritis and the importance of laboratory tests such as anticytoplasmic autoantibodies (ACPA). The following DPH syndromes were encountered: antibasement membrane antibody (ABMA) disease (four cases); idiopathic pulmonary hemorrhage (four cases); Wegener's granulomatosis (WG) (five cases); probable WG (six cases); systemic necrotizing vasculitis otherwise unclassified (three cases); systemic lupus erythematosus (two cases); rheumatoid arthritis (one case); seronegative juvenile rheumatoid arthritis (one case); IgA nephropathy (one case); idiopathic glomerulonephritis (two cases--one with and one without immune complexes); and unclassified pulmonary-renal syndromes (five cases). Capillaritis was found in lung biopsy samples from 30 of the 34 patients (88%) and included patients with every type of DPH syndrome. Serologic testing for ACPA was useful in the diagnosis of WG. Identification of ABMA in the serum, kidney, or lung was the defining feature for the diagnosis of ABMA-mediated disease. Subclassification of the cases could not be done solely on histologic grounds except for cases of WG that showed granulomatous inflammation, foci of necrosis, or vasculitis. Classification of the remaining cases required correlation with (a) clinical and laboratory data; (b) biopsy samples from other sites such as the kidney, nasal sinuses, or skin; and (c) results of immunofluorescence or electron microscopy of kidney or lung biopsy samples.

Adolescent↗
PubMed1990

Characterization of the angiotensin II receptor.

We present a brief overview of the present knowledge on the structural and molecular properties of angiotensin II receptors and the various attempts to determine their primary structures, with special reference to our strategy for receptor purification. The strategy involves covalent labeling of the receptor with synthetic biotinylated photoactivatable probes, followed by indirect affinity chromatography on immobilized streptavidin. The various applications of these probes to the study of structural and molecular properties and to the cell biology of angiotensin II receptors are discussed.

Amino Acid Sequence↗
PubMed1989

Influence of bacterial toxins and forskolin upon vasopressin-induced inositol phosphate accumulation in WRK 1 cells.

The accumulation of inositol phosphates in WRK 1 cells, stimulated with a range of vasopressin concentrations, was diminished by prior exposure to cholera toxin or forskolin, whilst that observed in the presence of maximal concentrations of the hormone was enhanced in pertussis-toxin-treated cells. In the presence of [32P]NAD+, both cholera toxin and pertussis toxin provoked the labelling of peptides with approximate Mrs of 45,000 and 41,000 respectively in the membranes of WRK 1 cells. Exposure to cholera toxin or forskolin for 15-18 h enhanced cyclic AMP accumulation in these cells. The concentrations of these agents which provoked half-maximal cyclic AMP accumulation were similar to those required to diminish receptor-mediated inositol phosphate accumulation by 50%. In contrast, half-maximal ADP-ribosylation of the 45,000Mr peptide needed 100-fold greater concentrations of the toxin than were effective in provoking half-maximal inhibition of inositol phosphate accumulation. Cholera toxin or forskolin also reduced the maximal specific binding, to intact WRK 1 cells, of both [3H][Arg8]vasopressin and the V1a antagonist [3H][beta-mercapto-beta,beta-cyclopentamethylenepropionic acid,O-methyl-Tyr2, Arg8]vasopressin. The kinetics for the loss of this binding capacity following cholera-toxin treatment were very similar to those describing the diminution of vasopressin-stimulated inositol phosphate accumulation in the same cells.

Adenosine Diphosphate↗
PubMed1989

Diagnostic value of ascites adenosine deaminase in tuberculous peritonitis.

The value of ascitic fluid adenosine deaminase activity in distinguishing tuberculosis from other causes of ascites was examined in a retrospective study of 41 patients with bacteriologically confirmed tuberculous peritonitis and 41 control patients, matched for age and sex, with ascites of other causes (12 alcoholic cirrhosis, 5 cryptogenic cirrhosis, 12 malignant disorders, 3 pancreatitis, and 9 miscellaneous causes). The mean ascites adenosine deaminase activity was 99.8 (SD 49.1) in tuberculous patients and 14.8 (8.4) U/l in control patients (p less than 0.0001). A cutoff of 32.3 U/l had a sensitivity of 95% and specificity of 98% in distinguishing between the two groups. In a subsequent prospective study of 64 patients with ascites, 11 were found to have tuberculosis. Of the others, 23 had cirrhosis (18 alcoholic, 5 cryptogenic), 17 malignant disorders, 3 pancreatitis, 5 cor pulmonale, 3 congestive cardiac failure, 1 systemic mastocytosis, and 1 renal failure and hypothyroidism. The mean ascites adenosine deaminase activity was 112.6 (45.0) U/l in the patients with tuberculous ascites and 16.3 (36.7) U/l (p less than 0.0001) in those with ascites of other causes. In this study, adenosine deaminase had a sensitivity of 100% and specificity of 96% in discriminating tuberculosis from other causes of ascites. These findings suggest that the ascitic fluid adenosine deaminase activity may be used to identify patients in whom the diagnosis of abdominal tuberculosis must be pursued.

Adenosine Deaminase↗
PubMed1989

Properties of membranous phospholipase C from WRK1 cell: sensitivity to guanylnucleotides and bacterial toxins.

As previously described, WRK1 plasma membrane possesses a vasopressin-sensitive phospholipase C [G. Guillon et al., 1986, FEBS Lett. 196, 155-159]. In the present study, we examined the sensitivity of this enzyme to guanylnucleotides. GTP gamma S induces a time- and dose-dependent stimulation of Ins(1,4,5)P3 and Ins(1,4)P2 accumulation. No accumulation of InsP1, Ins(1,3,4)P3 or Ins(1,3,4,5)P4 occurred under similar conditions. Gpp(NH)p produced the same effect but was less potent. GTP and a nonhydrolyzable analogue of ATP, App(NH)p, were without effect. Calcium also stimulated the phospholipase C activity in a time- and dose-dependent manner. In the absence of calcium, the activity of GTP gamma S was considerably reduced. Physiological calcium concentrations (between 10(-8) and 10(-7) M), allowed maximal GTP gamma S stimulation of phospholipase C activity. In this system, the presence of vasopressin alone did not generate inositol phosphate accumulation. However, this hormone: (i) reduced the lag-time observed during GTP gamma S stimulation, (ii) increased the sensitivity of phospholipase C to GTP and to GTP gamma S, and (iii) did not modify the stimulation of phospholipase C induced by maximal doses of GTP gamma S. Unlike sodium fluoride, GTP gamma S elicited an irreversible activation of phospholipase C. Calcium, GTP gamma S and sodium fluoride stimulated the phospholipase C activity via mechanisms sharing a common step, since their maximal effects were not additive. Cholera toxin treatment, known to produce complete ADP-ribosylation of 'alpha s' subunits, partially reduced the basal and the maximal GTP gamma S-mediated stimulation of phospholipase C activity as well as that caused by vasopressin. This inhibition was not mimicked by treatment with either forskolin or pertussis toxin.

Adenosine Diphosphate Ribose↗
PubMed1989

Lymphoepithelioma-like carcinoma of the lung.

Originally described in the nasopharynx, lymphoepitheliomas are undifferentiated carcinomas with prominent lymphoid infiltration. Recently this tumor has been described in a number of other sites. An association with prior infection by the Epstein-Barr virus has been recognized in cases from the nasopharynx. We report four cases of lymphoepithelioma-like carcinoma arising in the lung. Epstein-Barr virus serology indicated prior infection in two cases, one of which was also found by in situ hybridization to have the virus genome. Lymphoepithelioma-like carcinoma must be considered in the differential diagnosis of primary lung tumors, particularly when an extensive infiltrate by lymphoid tissue is present and may even suggest lymphoma.

Aged↗
PubMed1989

[Chronic diarrhea with hypergastrinemia and achlorhydria without gastritis in a 5-year-old child].

We report a case of chronic diarrhea due to hypergastrinemia with achlorhydria but without gastritis in a five-year-old boy. Symptoms responded promptly to oral administration of hydrochloric acid and resolved completely after one year of treatment. The pathophysiologic situation in this patient closely resembled that normally seen in neonates, suggesting prolonged but nevertheless transient immaturity of gastric secretions.

Achlorhydria↗
PubMed1989

Effect of N2O on segmental left ventricular function and effective arterial elastance in pigs when added to a halothane-fentanyl-pancuronium anesthetic technique.

The interaction of various concentrations of N2O and a stable halothane-fentanyl-pancuronium anesthetic technique was examined in nine pigs. Segmental myocardial contractility was measured with the end-systolic pressure-length relationship (Ees), and the effective arterial elastance (Ea) was quantified based on the Windkessel model. The addition of 30, 50, and 70% N2O did not change myocardial contractility or the effective arterial elastance. During the 30 and 70% N2O challenge, however, arterial capacitance decreased significantly from a mean (+/- SEM) 0.86 +/- 0.15 to 0.71 +/- 0.0.11 mL/mm Hg with 30% N2O (P less than 0.05) and from 0.90 +/- 0.09 to 0.71 +/- 0.07 mL/mm Hg (P less than 0.05) with 70% N2O. A dose-response relationship for the effect on the arterial capacitance could not be demonstrated. We concluded that in the presence of halothane, fentanyl, and pancuronium, N2O does not depress the normal myocardium or change left ventricular afterload. The decrease in arterial capacitance that occurred when 30 and 70% N2O were given was not sufficient to change the effective afterload and appears to be of no importance to normal left ventricular function.

Animals↗
PubMed1989

Effect of various propofol plasma concentrations on regional myocardial contractility and left ventricular afterload.

The cardiovascular effects of propofol infusions, designed to maintain constant plasma concentrations, were examined in an open-chested pig model. Regional myocardial contractility was measured with the end-systolic pressure-length relationship (Ees) and left ventricular afterload quantified by the effective arterial elastance (Ea). The propofol plasma concentrations in this study varied between 0 and 7.73 (SEM 0.96) micrograms/mL. A significant correlation for the increasing propofol plasma concentration and a decrease in myocardial contractility (P = 0.0056) was demonstrated, and the Ea remained constant. This gave rise to a reduction in stroke volume (P = 0.002) and, combined with a decrease in the heart rate (P = 0.0001), led to a reduction in the cardiac output (P = 0.0001). When the propofol infusion was stopped, myocardial contractility did not recover in parallel with the decrease in plasma propofol concentration.

Anesthetics↗
PubMed1988

Cholera-toxin and corticotropin modulation of inositol phosphate accumulation induced by vasopressin and angiotensin II in rat glomerulosa cells.

Vasopressin (VP) and angiotensin II (AT II) stimulate the production of inositol phosphates (IP) in rat glomerulosa cells. Guanosine 5'-[gamma-thio]triphosphate (GTP[S]), but not VP or AT II, stimulates IP production in a myo-[3H]inositol-prelabelled glomerulosa-cell membrane preparation. In combination with GTP[S], these hormones potentiate the response to GTP[S], indicating the existence of a G-protein involved in the coupling of the VP and AT II receptor with the phospholipase C. ADP-ribosylation with pertussis toxin (IAP) revealed the specific labelling of a single molecule of 41 kDa. No significant inhibition of VP- or AT II-stimulated IP accumulation was detected in intact cells when the whole 41 kDa molecule was endogenously ADP-ribosylated by IAP treatment. On the contrary, when glomerulosa cells were infected with cholera toxin (CT), both the VP- and AT II-stimulated IP accumulations were inhibited in a dose-dependent manner. Yet these effects were partial even at high concentrations of CT, and could not be related to the ADP-ribosylation of 'alpha s' molecules. Similarly, when the cells were infected with 1 microgram of CT/ml, the specific binding of VP and AT II decreased by 50-60%. Such results may signify that the treatment primarily affects the densities of the hormone receptors. When glomerulosa cells were incubated for 15 h in the presence of 10 nM-corticotropin (ACTH), a condition in which the intracellular concentration of cyclic AMP was increased 3-fold, the maximum IP response to 0.1 microM-VP or -AT II was decreased by 50%. When similar experiments were carried out only after a 15 min incubation period with the same concentration of ACTH, the increase in cyclic AMP was more pronounced, but no inhibition of hormone-induced IP accumulation was observed. Altogether, these results may suggest that CT exerts its action on the VP- or AT II-sensitive phospholipase C systems via a prolonged increase in intracellular cyclic AMP.

Adenosine Diphosphate↗