Interet diagnostique d’une injection intracaverneuse de 20 μg de Prostaglandine E1 dans l’impuissance

Intracavernous injection of 20 μg of prostaglandin E1 (PGE1) was carried out in 130 impotent patients. The erectile response was compared to the results of arteriological investigations including nocturnal penile tumescence and rigidity monitoring (NPTR) in 59 patients. The response of 60 patients positively categorized as exclusively psychogenic or vasculogenic was also compared to the pattern of the response to 80 mg of papaverine observed in a previous study by the same authors. The PGE1 test may not discriminate psychogenic from wholly organic patients since its results are not correlated to those of NPTR. It helps for the screening of vasculogenic impotence. Lack of response or a partly rigid response is consistent with this actiology but is not specific for it. A fully response makes it unlikely. Compared to papaverine, PGE1 induces less non rigid responses in psychogenic patients (15% versus 35% with papaverine) and more fully rigid responses in vasculogenic patients (respectively 12% and 5 %). Consequently the specificity of the PGE1 test is higher but its sensitivity lower than that of papaverine so that there is no clear difference in the effectiveness of the tests. Nevertheless the PGE1 test should be preferred, because it is safer. Prolonged erections occured in only 5 patients, and all ceased spontaneously. However 4 presented severely painful erections.     

Direct measurement of hydration-related dynamic changes in lysozyme using inelastic neutron scattering spectroscopy

Inelastic neutron scattering spectroscopy is used to investigate dynamic changes in lysozyme powder at two different low D2O hydrations (0.07g D2O/g protein and 0.20 g D2O/g protein). In the higher hydration sample, the inelastic scattering between 0.8 and 4.0 cm-1 energy transfer is increased and the elastic scattering is decreased. The decreased elastic scattering suggests increased atomic amplitudes of motion and the increased 0.8 to 4.0 cm-1 scattering suggests increased motions in this frequency range. Comparison with normal mode models of lysozyme dynamics shows that the inelastic difference occurs in the frequency region predicted for the lowest frequency, largest amplitude, global modes of the molecular [M. Levitt, C. Sander and P.S. Stern, J. Mol. Biol. 181, 423 (1985). B. Brooks and M. Karplus, Proc. Natl. Acad. Sci (U.S.A) 82, 4995 (1985), R.E. Bruccoleri, M. Karplus and J.A. McCammon, Biopolymers 25 1767 (1986)]. Our results are consistent with a model in which an increased number of low frequency global modes are present in the higher hydrated sample.     

A trophic effect of epidermal growth factor (EGF) on rat colonic mucosa in organ culture

Abstract. The development of an organ-culture system for rat colonic mucosa has enabled a direct assessment of the effect of epidermal growth factor (EGF) on cell division. An augmented mitotic index (AI_m) has been employed to identify changes in cell proliferation.
Explants of colonic mucosa from four animals were maintained in a medium containing serum for five days. On the fifth day of culture, half of the explants received fresh medium containing EGF (40 ng/ml) and the remainder (controls) fresh medium only. At 6,12,24 and 48 hr thereafter groups of both experimental and control explants received the metaphase-arresting drug vincristine (4 μ g/ml) for 3 hr prior to fixation. The proportions of vincristine-arrested metaphases within the explants were determined. Analysis of the data indicates that when serum is present exogenous EGF exerts a trophic effect which increases with time ( P < 0.001).
In a second experiment colonic explants from four animals were maintained for five days in a serum-free medium and were then divided into groups, each of which received one of a range of concentrations of EGF. The AI_m was determined for each group after 36 hr. It was found that increasing concentrations of EGF produce a small but significant increase in cell proliferation ( P < 0.01). This effect, however, was less pronounced than that seen when serum was present.
These results suggest that EGF has a trophic action on the colon and interacts with additional factors found in serum.     

Inositol lipids and phosphates in the regulation of the growth and differentiation of haemopoietic and other cells

Stimulation of phosphatidylinositol 4,5-bisphosphate hydrolysis is an important signalling reaction involved in the responses of cells to some, but not all, stimuli that promote cell proliferation. Active agents in this regard include antigens activating T and B lymphocytes, angiotensin (employing a receptor encoded by the mas oncogene), bombesin and platelet-derived growth factor PDGF). However, accumulating evidence suggests that inositol lipids and phosphates also have other roles in the regulation of cell growth and differentiation. Growth factor receptors that encode tyrosine kinases (such as that for PDGF) activate a kinase that synthesises phosphatidylinositol 3-phosphate, a novel lipid, and loss of this kinase-activating function abolishes growth-promoting activity. Human interleukin-4, a lymphokine that activates B lymphocytes, appears to employ phosphatidylinositol 4,5-bisphosphate hydrolysis as a brief initial signal that is followed by a sustained rise in cyclic adenosine monophosphate (cAMP): both signals are needed for the successful induction of the surface antigen CD23. Moreover, the same inositol lipid signalling pathway as is employed by antigen-stimulated mature T lymphocytes to provoke proliferation may be redeployed in immature T cells to trigger their elimination when they encounter self-antigens. Finally, studies of HL60 promyelocytic cells have shown that these cells contain high concentrations of inositol 3,4,5,6-tetrakisphosphate, 1,3,4,5,6-pentakisphosphate and hexakisphosphate, three inositol polyphosphates that are probably formed independently of inositol lipid metabolism. When these cells are induced to differentiate either towards neutrophils (in the presence of dimethylsulphoxide) or macrophages (in phorbol myristate acetate), cessation of growth and acquisition of differentiated characteristics are accompanied by large and different changes in the concentrations of these inositol phosphates that may be characteristic of these two pathways of differentiation.     

On Presenting Results of Statistical Analyses in Scientific Journals

In many biological and other scientific journals, a reader's understanding of a paper to the argument of which statistical methods and analyses are important is often impeded by confusions of terminology and ambiguities of symbols. This is not solely because statistics is a difficult subject for biologists! If an editor were to formulate and make known a code of statistical symbols, abbreviations, and technical terms that in his journal will be regarded as part of the normal language of science, an author could use these without need for explanation each time. Every author would remain free to depart from the code, provided that he defined clearly his own usages. Such a policy, supported by the journal's referees, would do much to remove the frequent necessity for a reader to guess an author's meaning. Similarly considerations apply to the use of statistical software packages, where there is an evident need for an author to declare what software (if any) he has used, in much the same way as, by established custom, he will carefully specify his experimental materials and methods where these in any respect differ from the obvious. The present paper is written to stimulate constructive debate, and in no way to dogmatize on the merits or faults of particular statistical methods. Its underlying spirit is that the author of a scientific communication has a duty to describe the making of his observations, the conduct of his computations, and the performance of his computations with a clarity that would permit their repetition by another scientist who has access to the appropriate facilities and resources.     

Proliferative status of colonic mucosa in organ culture: 3H-thymidine-labelling studies and computer modelling

3H-thymidine labelling studies and a computer simulation have been employed to assess proliferative status and cellular organisation in colonic explants maintained in culture for 5 to 7 days. The one-hour flash labelling index (Is) for crypts within the middle region of explants (5.2%) was considerably lower than that observed in vivo (8.8%). Crypt length and the distribution of labelled cells appeared similar for both situations. A computer simulation program for crypt-cell proliferation was devised, facilitating the modulation of a number of parameters including the cell-cycle time (Tc) and its component phases, the cut-off position, and cell loss at mitosis. This simulation was employed to model continuous labelling (72 h) data obtained in vitro and provided an estimate of various kinetic parameters. Data for the middle region of explants was fitted with a Tc of 62 h, an S phase of 8 h and a cell loss factor (20%) which was consistent with histological findings. A fit to the experimental data obtained in vitro could be achieved by a model based upon a mode of cellular organisation known to occur within crypts in vivo. Therefore in vitro, the dynamic processes of crypt-cell proliferation and migration appear to be organised in the same manner as seen in vivo.