Tissue distribution of beta 1- and beta 2-subunits of regulatory guanine nucleotide-binding proteins

The beta-subunit of G-proteins occurs in two forms (beta 1 and beta 2), which differ in their primary structure as derived from cDNA clones and in their mobilities on SDS gels (36 and 35 kDa, respectively). To assess the tissue distribution of the two forms of beta-subunits, we synthesized peptides corresponding to defined regions of beta 1- and beta 2-subunits and injected them into rabbits; the antisera obtained reacted either with both beta-subunits or specifically with the beta 1- or the beta 2-subunit. They were used to identify the two beta-subunits in membranes prepared from various rat tissues and from human placenta. The concentration of total beta-subunits was high in rat brain and lung, human placenta, rat kidney, liver and spleen; it was much lower in rat erythrocytes, cardiac and skeletal muscle. In all tissues studied, both beta 1- and beta 2-subunits were detectable. In most tested tissues, the two forms were about equally distributed, whereas in the placenta, the beta 2-subunit was found to occur in approx. 2-fold excess over the beta 1-subunit. Our results demonstrate that both beta-subunits are widely distributed. In the majority of tissues, levels of beta 2-subunits are very similar to those of beta 1-subunits. Thus, the abundance of beta 2-subunits as compared to that of the beta 1-subunit is considerably higher than was previously estimated by measuring the respective mRNA levels.     

Computer-assisted grading of adenocarcinoma in prostatic aspirates

Conventional cytologic grading of fine needle aspirates of prostatic adenocarcinoma has been shown neither to be reproducible nor to correlate well with histologic grading. This study developed a tumor grade classification based on computerized cytomorphometric features and compared the results to conventional grading of companion tissue sections. The image analysis system evaluated architectural features of the aspirates (mainly cell cluster features and interrelationships) as well as nuclear features. Thirty-five prostatic adenocarcinomas (8 well, 19 moderately and 8 poorly differentiated) were evaluated. Discriminant functions based on data collected at medium and high resolution distinguished between aspirates from low-grade (well-differentiated) and high-grade (poorly differentiated) adenocarcinomas with 81% accuracy. Moderately differentiated cancers could not be classified as a distinct group. This study suggests that accurate grading of prostatic adenocarcinoma in fine needle aspirate smears requires the evaluation of medium-resolution features related to specimen cellularity and uniformity or crowding of cell clusters as well as of high-resolution features of nuclear area, perimeter and coarseness of chromatin texture. These findings are compared to those of other schemes for the cytologic grading of prostatic aspirates.     

Cyclic AMP-independent, dual regulation of voltage-dependent Ca2+ currents by LHRH and somatostatin in a pituitary cell line.

Voltage-dependent Ca2+ currents appear to be involved in the actions of hormones that regulate pituitary secretion. In order to investigate modulation of Ca2+ currents by release-inducing and release-inhibiting hormones, we performed whole-cell clamp experiments in the pituitary cell line GH3. The resting potential was approximately -40 mV; spontaneous action potentials were observed in the majority of cells. Superfusion of cells with the stimulatory hormone, LHRH, depolarized the plasma membrane to approximately -10 mV, whereas the inhibitory hormone, somatostatin, caused hyperpolarization to approximately -60 mV; both hormones suppressed spontaneous action potentials. Under voltage clamp conditions, GH3 cells exhibited slowly and fast inactivating Ca2+ currents. LHRH increased whereas somatostatin decreased the slowly inactivating currents; fast inactivating currents were not affected by these hormones. The stimulatory effect of LHRH was not mimicked by intracellularly applied cAMP. In contrast to vasoactive intestinal peptide and forskolin, LHRH did not activate adenylate cyclase in membranes of GH3 cells, but rather appeared to cause inhibition of the enzyme. Hormonal stimulation and inhibition of inward currents were abolished by pretreatment of the cells with pertussis toxin. In membranes of GH3 cells, we identified a pertussis toxin-sensitive G-protein of the Gi-type and Go. We conclude that LHRH and somatostatin modulate voltage-dependent Ca2+ currents via cAMP-independent mechanisms involving pertussis toxin-sensitive G-proteins. The occurrence of both pertussis toxin-sensitive hormonal stimulation and inhibition of voltage-dependent Ca2+ currents in one cell type suggest that these opposite regulations are mediated by distinct G-proteins.     

Mechanosensory interneurons (MSIs) in the crayfish 6th abdominal ganglion are inhibited by activation of other MSIs

1. Identified mechanosensory interneurons (MSIs) in the 6th abdominal ganglion of the crayfish Procambarus clarkii have been shown to inhibit other projecting MSIs. 2. Interneurons sensitive to water-current stimulation of the tailfan, and which inhibited the tactile response of other MSIs when activated by depolarizing currents, were identified by iontophoresis of fluorescent dye. 3. Ten inhibitory interneurons have been identified, including both non-adapting, directional cells and phasic "touch" cells. 4. Inhibition triggered by activation of the identified cells was not widespread among fibers in the connectives. 5. Inhibition recorded intracellularly was mediated by compound inhibitory postsynaptic potentials of long duration (300-400 msec) and latencies of 13-15 msec, and therefore was apparently polysynaptic. 6. Depolarization and/or activity in MSIs, which modulates the stimulus response characteristics of related cells is a possible mechanism for contrast enhancement among directional or frequency-selective interneurons.     

Poorly expressed endogenous ecotropic provirus of DBA/2 mice encodes a mutant Pr65gag protein that is not myristylated.

DBA/2 mice carry a single endogenous ecotropic murine leukemia provirus designated Emv-3. Although this provirus appears to be nondefective by genomic restriction enzyme mapping, weanling mice do not produce virus and only about one-third of adult mice ever express virus. 5-Iododeoxyuridine and 5-azacytidine, two potent inducers of ecotropic virus expression, are relatively ineffective at inducing Emv-3 expression. However, the chemical carcinogen 7,12-dimethylbenz(a)anthracene can induce ecotropic virus expression in approximately 95% of treated DBA/2 mice. Previous experiments involving DNA transfection and marker rescue analysis of molecularly cloned Emv-3 DNA suggested that Emv-3 carries a small defect(s) in the gag gene, not detectable by restriction enzyme mapping, that inhibits virus expression in vivo and in vitro. Using a combination of approaches, including DNA sequencing, peptide mapping, and metabolic labeling of cells with [3H]myristate, we have demonstrated that the defect in Emv-3 most likely results from a single nucleotide substitution within the gene for p15gag that inhibits myristylation of the Pr65gag N terminus. Myristylation of Pr65gag is thought to be required for this protein to associate with the plasma membrane and is essential for virus particle formation. These results provide a conceptual framework for understanding how Emv-3 expression is regulated during development and after chemical induction.     

Allometric shape change and heterochrony in the freeliving coral Trachyphyllia bilobata (Duncan)

Regression analysis has been used to study the relationship between age, size, shape, and surface area in two ancestral-descendant populations of the Neogene Caribbean coral Trachyphyllia bilobata. Analyses of the relationship between size and age show that the relationship is isometric and that little difference occurs between populations in mean corallite length or height and in their rates of growth. Onset of columella growth is significantly earlier, however, in the descendant population. Studies of the relationship between size and shape show that growth is allometric, with shape change occurring in both corallum elongation and pinching of the corallite wall during ontogeny. In the descendant population, pinching and elongation initiate earlier in the ontogeny of the coral. These results suggest that the evolutionary development of the meandroid form in freeliving corals has been accomplished by heterochrony, involving a complex set of disassociated peramorphic changes in ontogeny accompanied by paedomorphic changes in astogeny. Further analyses show that the observed heterochronic changes serve to decrease corallum surface area which may in turn enhance sediment removal and nutrition in unstable habitats.     

Inhibition of lettuce seed germination by cycloheximide and chloramphenicol is alleviated by kinetin and oxygen

Kinetin alleviates cycloheximide inhibition and oxygen alleviates chloramphenicol inibition of germination of lettuce seeds (Lactuca sativa L. cv Grand Rapids). The effect is not due to increased but rather a substitution for protein synthesis. A cytokinin and energy supply appear prime requirements for germination.     

Sexual contact in the doctor-patient relationship in The Netherlands.

OBJECTIVE--To obtain data on sexual contact between doctors and their patients. DESIGN--Anonymous questionnaire with 17 items sent to all working gynaecologists (n = 595) and all ear, nose, and throat specialists (n = 380) in the Netherlands. RESULTS--Response rate was 74%; a total 64 doctors gave a reason for not completing the questionnaire. 201 (59%) male gynaecologists and 128 (56%) male ear nose, and throat specialists indicated that sexual feelings are acceptable in the doctor-patient relationship; 286 (85%) and 186 (81%), respectively, had felt sexually attracted to a patient at some time, as had 14 (27%) female gynaecologists. More than half (59%) of the doctors who indicated that sexual feelings are unacceptable in the doctor-patient relationship had experienced these feelings, and 91% of this group had a negative attitude towards these feelings. 4% of respondents in each group had had actual sexual contact with patients. Most gynaecologists were in favour of having more attention paid to sexual problems during training; having their professional society take an official viewpoint; subsequent public support of this viewpoint; and taking on an impartial counsellor for the patients as well as the doctors. CONCLUSION--Sexuality exists in the doctor-patient relationship. Gynaecologists have a higher risk of having sexual contact with their patients than do ear, nose, and throat specialists but compensate for this greater risk by a higher state of recognition and acknowledgement.