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Biomedical subjects

J Hoffmann

Publications and source records attributed to J Hoffmann.

At least 199 records · Page 11Linked to original sources
PubMed1990

Enhanced expression of the proto-oncogenes fos and raf in the rhabdomyosarcoma cell line BA-HAN-1C after differentiation induction with retinoic acid and N-methylformamide.

BA-HAN-IC is a clonal rat rhabdomyosarcoma cell line consisting of proliferating mononuclear tumor cells, some of which spontaneously fuse to form terminally differentiated post-mitotic myotubes. Exposure of BA-HAN-IC cells to retinoic acid (RA) or N-methylformamide (NMF) resulted in a significant inhibition of proliferation (p less than 0.001) and in cellular differentiation, as evidenced by a significant increase in the creatine kinase (CK) activity (p less than 0.05) and the number of terminally differentiated post-mitotic myotubes (p less than 0.001). Furthermore, between 5% (NMF) and 30% (RA) of the mononuclear tumor cells exhibited ultrastructural features of rhabdomyogenic differentiation, not observed in their mononuclear counterparts under standard growth conditions. Although BA-HAN-IC cells responded to both inducers of differentiation, differences in time course and magnitude of both increase of differentiation and growth inhibition were observed. These effects of RA and NMF were preceded by a marked enhancement of c-raf expression which became evident 6 and 12 hr after exposure to RA and NMF, respectively, and which persisted throughout the observation period of 5 days. Furthermore, a transient expression of c-fos could be observed 15 and 30 min after exposure to RA. Our results suggest that c-raf expression might be implicated in the differentiation process of BA-HAN-IC tumor cells.

Animals↗
PubMed1990

Interaction of Triton X-100 and octyl glucoside with liposomal membranes at sublytic and lytic concentrations. Spectroscopic studies.

The molecular mechanism of the solubilisation of phospholipid bilayers by nonionic detergents was studied by turbidity changes, carboxyfluorescein fluorescence dequenching, steady-state and time-resolved fluorescence anisotropy of DPH, lifetime measurements, ANS binding and 31P-NMR. Particular attention has been paid to the effective detergent-to-lipid ratio in the lipid phase. The disturbance of the bilayer arrangement varies considerably for various detergents depending on the hydrophilic and lipophilic parts of the molecule. Small amounts of detergents with low CMC (e.g. Triton X-100) can even induce an optimisation of packing of the lipid molecules.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1990

Isolation and structure elucidation of a novel 5-kDa peptide from neurohaemal lobes of the corpora cardiaca of Locusta migratoria (Insecta, Orthoptera).

Two predominant peptides have been isolated from neurohaemal lobes of corpora cardiaca of 8000 adults of Locusta migratoria. Both peptides have been unambiguously characterized by automated peptide microsequencing and liquid secondary-ion mass spectrometry as a 50-residue peptide (5K peptide) and a 48-residue isologue (5K' peptide). Computer search of sequence data banks did not reveal any significant similarity with other identified proteins. The 5K peptides are remarkably rich in alanine residues (25%) and contain a stretch of five consecutive alanines. This structure suggests that these molecules could correspond to spacer peptides. This assumption is corroborated in the accompanying paper [Lagueux et al. (1990) Eur. J. Biochem. 187, 249-254] on the molecular cloning of the precursor protein which attributes to the 5K peptides a role analogous to that of the C peptides of insulins.

Amino Acid Sequence↗
PubMed1990

Diurnal salivary cortisol patterns during pregnancy and after delivery: relationship to plasma corticotrophin-releasing-hormone.

The circadian rhythm of salivary cortisol was studied in 10 healthy women every 4 weeks throughout pregnancy. In addition, in 12 women the diurnal patterns of salivary cortisol, serum cortisol, plasma ACTH, plasma CRH and serum progesterone were analysed in late third trimester pregnancy and again 3-5 days after delivery. Salivary cortisol profiles exhibited a clear circadian rhythm during pregnancy with an increase in mean salivary cortisol from the 25th to 28th week onwards reaching concentrations in late pregnancy more than twice as high as in non-pregnant controls, rapidly returning to normal concentrations after delivery. The coefficient of variation of salivary cortisol profiles decreased in third trimester pregnancy due to a parallel upward shift of cortisol concentrations (40.2 +/- 3.4% vs 77.6 +/- 6.6% after delivery, P less than 0.01). A diurnal pattern was also found for plasma ACTH and serum cortisol before and after delivery with lower concentrations post-partum (P less than 0.01). In late pregnancy, progesterone concentrations were significantly higher in the evening (930 +/- 85 nmol/l vs 813 +/- 74 nmol/l at 0900 h, P less than 0.01) but showed no diurnal variation post-partum. Plasma CRH was significantly elevated in late third trimester pregnancy (1.22 +/- 0.23 micrograms/l at 0900 h) but showed no diurnal change (1.30 +/- 0.28 micrograms/l at 1900 h). Moreover, no correlation between the free cortisol increase in late pregnancy and plasma CRH was noted despite a wide range of CRH levels (0.13-3.60 micrograms/l). In contrast, a significant correlation was observed between the serum progesterone increase and the salivary cortisol increase in late pregnancy (r = 0.70, P less than 0.05). These findings demonstrate that placental CRH is not the only regulator of maternal ACTH and cortisol release. Instead, our study suggests that placental CRH has little influence on baseline maternal adrenocortical function in pregnancy. The elevated salivary cortisol levels in pregnancy may be explained by glucocorticoid resistance owing to the antiglucocorticoid action of high progesterone concentrations.

Adult↗
PubMed1990

Unilateral parathyroidectomy: the role of thallium-technetium subtraction scans.

The rationale for using the thallium-technetium subtraction scan as a preoperative localizing study in previously untreated patients with primary hyperparathyroidism is presented. The concept of unilateral parathyroidectomy is also presented, and the role of preoperative localizing studies in this approach to parathyroid surgery is carefully analyzed.

Adenoma↗
PubMed1990

[Cycloplatin (LACHEMA) in ovarian carcinoma. Results of a registered study].

A short report is given on the first results of the Carboplatin registration trial in ovarian cancer. CR 3/10 pat. PR 4/10 pat. remission time 10 ms in average. In comparison with cisplatin the efficacy is similar. The side effects are different particularly the bone marrow was more affected in contrast to cisplatin. The nephrotoxic side effects can be neglected.

Adult↗
PubMed1989

Co-ordinated changes in the cyclic AMP signalling system and the phosphorylation of two nuclear proteins of Mr 130,000 and 110,000 during proliferative stimulation of the rat parotid gland by isoprenaline. Possible identity of the two proteins with pp135 and nucleolin.

Parotid glands were stimulated to growth by repeated injection of the beta-agonist isoprenaline into rats. Incubation of intact parotid-gland lobules with [32P]Pi and subsequent analysis of nuclear proteins revealed in the stimulated glands an increased 32P incorporation into two acid-soluble non-histone proteins with apparent Mr values of 110,000 and 130,000 (p110 and p130). After a single injection of isoprenaline, leading to a biphasic increase in DNA synthesis (maximum at 24 h), the same two proteins showed a transiently increased 32P incorporation at 17 h after injection. At this time point at the onset of DNA synthesis the total activity of soluble cyclic AMP-dependent protein kinase decreased. No change in p110/p130 phosphorylation was observed at 0.3 h after stimulation, a time of maximal stimulation of secretion. Administration of the beta-antagonist propranolol 8 h after the injection of isoprenaline suppressed the increase in DNA synthesis, the preceding changes in the concentration of cyclic AMP and in the activity of cyclic AMP-dependent protein kinase, as well as the increased phosphorylation of p110 and p130. Cross-reactivity of p110 and p130 with specific antisera against two nucleolar phosphoproteins of similar molecular mass (nucleolin and pp135), as well as their localization in a nucleolar cell fraction, indicated a possible identity of p110 and p130 with these two proteins. Our results suggest that nucleolin and pp135 are nuclear target proteins of cyclic AMP in the cyclic AMP-influenced regulation of the transition of cells from the G1 to the S phase.

Blotting, Western↗
PubMed1989

[Diagnostic aids in acute appendicitis].

Acute appendicitis is usually diagnosed solely on clinical grounds. This results in a 15-30% incidence of unnecessary laparotomies and contributes to a perforation rate of 20-35%. The accuracies of eleven diagnostic aids for appendicitis are reviewed. The white blood cell count and straight x-ray of the abdomen are very unreliable. Four other methods, viz leucocyte scintigraphy, peritoneal lavage, barium swallow and scoring systems have not yet been sufficiently investigated. CT scanning may be useful in difficult cases. Four methods have a proven value and are recommended: Ultrasound scanning, computer assessment, laparoscopy and barium enema. Each of the latter are better than clinical assessment alone and can reduce both negative laparotomy rates and the incidence of appendicular perforation. Unaided clinical diagnosis of acute appendicitis is no longer acceptable.

Acute Disease↗
PubMed1989

Two daily doses of sucralfate or cimetidine in the healing of gastric ulcer. A comparative randomized study.

A double-blind, randomized study compared the healing of gastric ulcer during a twice-daily regimen of 2 g sucralfate or 400 mg cimetidine. The patients received the tablets one-half hour before breakfast and one-half hour before bedtime. The study included 76 patients with endoscopically proven gastric ulcer. Patients with ulcers less than 3 cm from the pyloric ring and patients with ulcers less than 3 mm in diameter were excluded from the study. Sixty-four patients completed the study. Healing was endoscopically assessed at four-week intervals for 12 weeks. After four, eight, and 12 weeks, the healing rates for cimetidine were 55, 81, and 94 percent, respectively; the healing rates for sucralfate were 52, 79, and 91 percent, respectively. No statistically significant difference was found between the two regimens. At 12 weeks, the risk of overlooking a difference in favor of one of the two dosage regimens was less than 20 percent. The results suggest that 2 g sucralfate twice daily is as effective in the healing of gastric ulcer as 400 mg cimetidine twice daily.

Adult↗
PubMed1989

Isolation and structure of two novel 6-kDa dimeric peptides from the corpora cardiaca of the insect Locusta migratoria. Molecular mass determination by mass spectrometry.

We have isolated two major 6-kDa peptides from extracts of corpora cardiaca of adult females of Locusta migratoria. These peptides have been characterized by peptide sequencing and liquid secondary-ion mass spectrometry. They are structurally related dimers, one (6278.5 Da) being a homodimer (A-A chains), the other (6280.5 Da) being a heterodimer (A-B chains). A 60% similarity exists between the A and B chains. Both peptides have been chemically synthesized and the synthetic compounds appeared to be identical to the native ones. Polyclonal antibodies raised against each of these peptides demonstrated that they were contained within the secretory granules of the intrinsic cells of the glandular lobes of the corpora cardiaca. The physiological significance of these two peptides is unknown but, using the synthetic peptides, we are currently probing their biological role.

Amino Acid Sequence↗