Muscarinic regulation of somatostatin release from primary cultures of human antral epithelial cells.

A newly developed, primary culture of human antral epithelial cells has been utilized to examine the effect of parasympathomimetics on somatostatin release. The cholinergic agonists, carbachol and methacholine, stimulated somatostatin secretion in a concentration-dependent manner. Maximal release in response to carbachol was observed at 0.1 mmol/l. Methacholine was 10 times more potent with a significant release being observed at 1 mumol/l, maximal secretion was observed at 10 mumol/l. Somatostatin release, stimulated by the mixed nicotinic and muscarinic agonist, carbachol, was attenuated by the addition of atropine at 0.1 mumol/l but was unaffected by the same concentration of pirenzepine. Methacholine-stimulated release was attenuated by addition of 0.1 mumol/l atropine and unaffected by the same concentration of pirenzepine. The response to methacholine was reversed by the addition of 0.1 mumol/l 4-diphenylacetoxy-n-methylpiperidine methiodide (4-DAMP) and attenuated by 1 nmol/l 4-DAMP indicating that the effect was mediated by an M3 receptor. In conclusion, human antral D cells are stimulated by parasympathomimetics acting at an M3 receptor.     

A phase I pharmacokinetic and pharmacodynamic study of the DNA methyltransferase 1 inhibitor MG98 administered twice weekly.

BACKGROUND: Hypermethylation and inactivation of tumor suppressor genes by the enzyme DNA methyltransferase may lead to neoplastic transformation. MG98, a phosphorothioate antisense oligodeoxynucleotide that is a specific inhibitor of mRNA for human DNA methyltransferase 1 (DNMT1), was evaluated in a phase I study. PATIENTS AND METHODS: MG98 was given as a 2 h i.v. infusion twice weekly three weeks out of every four to patients with solid tumors. Pharmacokinetic evaluation was performed on days 1 and 15 of cycle 1 and mRNA expression of DNMT1 was measured in peripheral blood mononuclear cells (PBMCs). RESULTS: Nineteen patients were entered onto the study. A total of 74 cycles (range 1-18 cycles) were administered at dose levels from 40 to 480 mg/m(2). Dose limiting toxicity was seen in two of three patients at 480 mg/m(2) and consisted of a constellation of fever, chills, fatigue and, in one case, confusion beginning within 6 h after the first infusion. Other toxic effects included fatigue, anorexia, nausea, vomiting and diarrhea, reversible elevations in transaminases and partial thromboplastin time. Pharmacokinetic evaluation showed C(max) and AUC to be dose proportional with low inter- and intra-patient variability. No consistent changes in DNMT1 mRNA expression were noted in PBMCs. One partial response was documented in a patient with renal cell carcinoma treated at 80 mg/m(2). CONCLUSIONS: The recommended dose of MG98 was 360 mg/m(2) given by 2 h infusion twice a week for three weeks out of every four. Phase II trials using this dose and schedule are underway.     

Radiation from ultraviolet phototherapy sources results in photodegradation of 12(R) and 12(S)-hydroxy-eicosatetraenoic acid: high-performance liquid chromatography and polymorph migration studies.

The effect of irradiation from Sylvania PUVA lamps (emitting predominantly in the ultraviolet (UVA) region) and broadband Philips TL-12 lamps (peaking in the UVB region) on two inflammatory mediators, 12(R)- and 12(S)-hydroxy-eicosatetraenoic acid (HETE) was studied. A high-performance liquid chromatography study showed significant photodegradation of both enantiomers at a concentration of 5 micrograms/ml in phosphate-buffered saline following irradiation with 10 J.cm-2 UVA or 0.375 J.cm-2 UVB. The in vitro chemokinetic microdroplet migration response of human peripheral polymorphonuclear leukocytes from normal and psoriatic subjects was significantly reduced following irradiation of 12(R)-HETE at a concentration of 1 micrograms/ml in medium with 40 J.cm-2 UVA and 1.5 J.cm-2 UVB respectively. No such effect was seen with 12(S)-HETE. The effect of ultraviolet on skin physiology, and in particular in the successful phototherapy of a range of inflammatory skin disorders, is not fully understood. The photodegradation of inflammatory mediators such as 12-HETE, as shown in this study, provides another factor of possible therapeutic significance.     

Chondrocytes in culture produce a mechanically functional tissue

A mechanically testable tissue was grown in vitro from rabbit chondrocytes that were initially plated at high density (approximately 80.000 cells/cm²). The DNA, collagen, and proteoglycan content, as well as the tissue thickness, tensile stiffness, and synthesis rates, were measured at 4, 6, and 8 weeks. The biochemical properties were similar to those for immature cartilage, with predominantly type-II collagen produced; this indicated that the cells retained their chondrocytic phenotype. The tissue formed a coherent mechanical layer with testable tensile stiffness as early as 4 weeks. The tensile elastic modulus reached 1.3 MPa at 8 weeks, which is in the range of values for native cartilage from the midzone. Collagen density was approximately 24 mg/ml at 8 weeks, which is about one-half the value for native cartilage, and the collagen fibril diameters were smaller. Chondrocytes in culture responded to culture conditions and were stimulated by cytokine interleukin-1β. When culture conditions were varied to RPMI nutrient medium with lower fetal bovine serum and higher ascorbic acid concentrations, the thickness decreased and the modulus increased significantly. Interleukin-1β. added to the 8-week culture for 2 weeks. caused a decrease of 60% in thickness, a decrease of 81% in proteoglycan content, and a decrease of 31% in collagen content; this is similar to the response of cartilage explants to interleukin-1β. This cartilage analog may be useful as a model system to study structure-function relationships in cartilage or as cartilage-replacement tissue.     

Visual function before and after the removal of bilateral congenital cataracts in adulthood.

Subject Peter Doyle (PD) had congenital bilateral cataracts removed at the age of 43. Pre-operatively PD's visual acuity was 20/80, with a resolution limit around 15 cpd, and he experienced monocular diplopia with high contrast stimuli. Post-operatively PD's visual acuity improved to approximately 20/40, with a resolution limit around 25 cpd. Using a variety of pre- and post-operative tests we have documented a wide range of neural adaptations to his limited and distorted visual input, and have found a limited amount of post-operative adaptation to his newly improved visual input. These results show that the human visual system is capable of significant adaptation to the particular optical input that is experienced.