Key peptide processing enzymes are expressed by a variant form of small-cell carcinoma of the lung

Small-cell carcinoma of the lung (SCCL) is a neuroendocrine tumor characterized by having the capacity to produce and secrete a number of small neuropeptides. These peptides serve the tumor as autocrine growth factors. SCCL is known to undergo a process of dedifferentiation to a variant (drug-resistant) form, and this process is associated with loss of marker enzymes such as neuron-specific enolase (NSE) and dopa decarboxylase (DDC). The current study was designed to discover if variant SCCL, represented by cell line NCI H82, retains some capacity to generate active neuropeptides (like vasopressin) from their precursors by continuing to express the three key classes of enzymes necessary for such conversions, namely prohormone convertases (PCs), carboxypeptidases (CPs), and peptidylglycine α-amidating monooxygenase (PAM). RT-PCR for mRNAs representing PC1, PC2, CPE, and PAM was performed on total RNA extracted from NCI H82. The primers selected for PCR and partial sequencing were synthetic 20, 21, 22, and 24 oligomers designed to yield products of 533, 880, 405, and 560 base pairs (bp) for PC1, PC2, CPE, and PAM, respectively. For the conditions used, we were able to demonstrate products for all four enzymes. Each of the four products generated were of the expected size. Cloning and sequencing of these products revealed that each had a structure identical to that published for the human form of the respective enzyme. Western analysis with antibodies against PC1, PC2, CPE, and PAM, provided evidence that mRNAs for the four enzymes are translated into proteins that could represent functional forms. Our findings therefore demonstrate that key enzymes involved in the generation of active neuropeptides, unlike the marker enzymes NSE and DDC, continue to be expressed by variant SCCL.     

Biological studies and research of immunologic deficiencies in blood donors from a prison environment

The prison population may be considered as a population at risk for AIDS. Biological parameters were studied in order to detect significant anomalies commonly observed in AIDS patients. With respect to are age matched control population of donors, there are no statistically significant differences concerning the nutritional and inflammatory states of the two populations. The investigation of the humoral immunity shows comparable levels of circulating antibodies in the two groups: a high level of anti-cytomegalovirus and anti-herpes antibodies is more frequently found in the penal population. The markers for hepatitis B were also studied. None of the individuals is a carrier of the HBs antigen. The percentage of individuals having biological markers of hepatitis B is higher in the at risk group (45%) than in the control group (10%). The evaluation of the cell-mediated immunity shows that there are no significant differences between the mean values found in the two groups for OKT3, T11, OKT4 and OKT8. There is no inversed OKT4/OKT8 ratio in the at risk group while one donor in the control group shows an inversed OKT4/OKT8 ratio.     

Hypotonic solution increases the slowly activating potassium current IsK expressed in xenopus oocytes.

A slowly activating potassium current was expressed in Xenopus oocytes by injection of RNA transcribed from a rat kidney cDNA clone. Hypotonic solutions (160 mOsmol/l; control was 220 mOsmol/l) increased the current by increasing the rate of activation and by decreasing the depolarization needed to activate the current. This effect of hypotonicity was not observed in calcium-free solution, but was unaffected by staurosporine or the calmodulin antagonist W7. Cytochalasin D reduced the current and prevented the increase by hypotonic solution. The results suggest that the increase in this potassium current by hypotonic solution might result from calcium entry and changes in the actin network.     

The many roles of small RNAs in leaf development

Leaf development involves many complex genetic interactions,signals between adjacent cells or between more distant tissues and consequent changes in cell fate.This review describes three stages in leaf development where regulation by small RNAs have been used to modulate gene expression patterns.     

TRACE METALS IN GIANT KELP,MACROCYSTIS

Concentrations of 38 elements present in Macrocystis tissues are listed. Mean concentrations of Cu, Zn, Fe, and Mn were similar for samples of juvenile and adult sporophytes from field sites. Cu in Macrocystis tissues rose above background levels when concentrations of 0.05 to 0.1 μm were added to the culturing medium. Above-normal accumulation for Zn occurred at 0.1 μm and for Fe at 10 μm . Tissue Mn appeared independent of the ambient Mn concentration over the ranges studied. Computations indicated that upwelling is important for N and P renewal to Macrocystis beds but may be less significant for import of trace metals.     

An apolipoprotein preferentially enriched in cholesteryl ester-rich very low density lipoproteins

Phosphatidyl glycerol is present in lamellar bodies and in the material obtained by alveolar wash representing 12.3 and 11.5%, respectively, of the total phospholipid phosphorus. Lung microsomes catalyze the formation of phosphatidyl glycerol from the known precursors, L-glycerol 3-phosphate and CDP-diglyceride. The rate of [¹⁴C]L-glycerol 3-phosphate incorporation into phosphatidyl glycerol was 30% higher in microsomes as compared to mitochondria. The addition of mercuric chloride inhibited the synthesis of phosphatidyl glycerol, and stimulated the incorporation into another as yet incompletely identified lipid. After pulse labeling of microsomal phosphatidyl glycerol $\text{in vitro}$, further incubation of microsomes with lamellar bodies or alveolar wash resulted in nearly quantitative appearance of label in surfactant.