Unusual splice sites revealed by mutagenic inactivation of an authentic splice site of the rabbit beta-globin gene

Only one of six point mutations of the sequence around one end of the larger of the introns of the rabbit beta-globin gene seriously affects the normal removal of the intron and splicing of the gene. That mutation converts a GT sequence, invariably found at the 5' end of introns, into an AT, which is no longer recognized as a signal for intron removal. Instead, three normally unused (cryptic) sites are used, leading to aberrant gene transcripts. One of the cryptic sites is an exception to the invariable GT sequence.

Image analysis: a consumer's guide

The last years have seen an explosion of systems in image analysis. It is hard for the pathologist or the cytologist to make the right choice of equipment. All machines are stupid, and the only valuable thing is the human work put into it. So make your benefit of the work other people have done for you. Chose a method largely used on many systems and which has proved fertile in many domains and not only for your specific to day's application: Mathematical Morphology, to which are to be added the linear convolutions present on all machines is a strong candidate for becoming such a method. The paper illustrates a working day of an ideal system: research and diagnostic directed work during the working hours, automatic screening of cervical (or other) smears during night.

Blood trauma during extracorporeal circulation: a comparison between two bubble and two membrane oxygenators in a standardized dog model

Determination of blood traumatization by extracorporeal circulation systems (ECC) in clinical trials may be interfered with by the underlying heart disease, by priming the circuit with blood or plasma expanders and by different operation techniques requiring a variable amount of coronary suction. Therefore, in this study a standardized animal model was used to compare blood traumatization in 2 bubble and 2 membrane oxygenators. After 2 hours of extracorporeal circulation, there was no advantage of the membrane over the bubble oxygenators concerning hemolysis, platelet preservation and induction of clotting factors. Red cells and platelets were traumatized in membrane oxygenators during the first 30 minutes without a significant further increase, whereas blood trauma in bubble oxygenators increased until bypass was disconnected. Therefore bubble oxygenators appear better suited for shorter perfusions, whereas membrane oxygenators are the superior choice in perfusions lasting longer than 2 hours.

[Relationship between dietary fibers and constipation (author's transl)]

Twenty-two women suffering from constipation were compared with an equal number of controls. Although both groups had similar mean daily total dietary fiber intake (12.4 and 12.7 g respectively) and mean daily cereal fiber intake (3.3 and 3.6 g respectively), the mean mouth-to-anus transit time for food was significantly longer (p less than 0.01) in constipated women (66.8 h) than in controls (48.5 h).

The release of pancreatic polypeptide by exogenous CCK in man and dog

4 healthy volunteers received commercial 20% pure CCK-33 in 4 consecutive doses of 0.5, 1.0, 2.0, 4.0 IDU/kg/h. blood samples were assayed for pancreatic polypeptide (PP) by radioimmunoassay. Plasma PP concentrations increased stepwise from a basal level of 67 +/- 15 pmol/l to a maximum of 198 +/- 46 pmol/l (p less than 0.05). In 4 mongrel dogs with Thomas cannulas, the same doses of 99% pure CCK-33 were successively infused. Plasma PP concentrations rose stepwise with each dose from 44 +/- 7 to 259 +/- 43 pmol/l (p less than 0.02). This rise significantly correlated with pancreatic protein secretion (p less than 0.01). It is concluded that intravenous CCK-33 induces the release of PP in man and in dog, in a dose-dependent manner.

Net albumin transport across the wall of the rabbit common carotid artery perfused in situ

We have studied the transport of radioactively labelled albumin in the rabbit common carotid artery perfused in situ at 100 cm H2O luminal pressure in the anaesthetized living animal, assessing the distribution of concentration across the wall by means of sequential frozen sectioning. We have compared the findings with those of experiments in which we have attempted to saturate the wall with label. Our findings support the belief that there is a net transport of macromolecules across the arterial wall. They show in addition that the wall is inhomogeneous. The distribution volume for label is greater in the adventitia than the media, which appears to offer a larger resistance. The transport process is seemingly dominantly diffusional.

[Chemical structure and biological activity of cholecystokizin octapeptides with respect to the stomach and pancreas]

Dose response curves of the octapeptide of cholecystokinin (CCK-8) and 3 of its methoxinine analogues have been established in 4 conscious dogs with respect to gastric and pancreatic secretion. In the analogues the methionine was replaced by methoxinine in position 3 (B) and (D) or 6 (C). Of the 4 tested substances CCK-8 exhibited most activity with regard to pancreatic protein secretion, followed by B, C, and D. Analogue C had the strongest stimulating effect on gastric acid secretion, while its effect on pancreatic secretion was minor. Correlation of chemical structure with biological activity points to the importance of the methionine residue in position 6.

[Corticosteroid-sensitive chemical diabetes in Horton's disease]

We report 5 cases of temporal arteritis associated with a diabetes whose good evolution under corticotherapy suggests a common pathogenesis. Several hypotheses can be formulated to explain the origin of the glycemic abnormality and to understand the way corticotherapy is effective. A moderate posology could at first have a hyperplasic effect on the insulin-secreting cells, and later on a favorable action on the vascular lesion and on an immunological disorder. Any definitive conclusion cannot be evolved yet. Only a more systematical study of the glycoregulation's abnormalities in the temporal arteritis will enable to answer the many remaining questions.

Reversed genetics: a new approach to the elucidation of structure--function relationship

Methods for generating point mutations at predetermined sites of RNA or DNA genomes have been developed. With Qbeta RNA as a template, minus strands were synthesized in vitro in a stepwise, substrate-controlled reaction. The nucleotide analogue N4-hydorxyCMP was introduced in the desired position, the minus strands were completed with the four standard triphosphates and used as templates to synthesize plus strands; about 30% of the progeny plus strands showed a base transition at the position corresponding to the nucleotide analogue. Two mutant RNAs with extracistronic nucleotide substitutions have been generated; one of these was viable, albeit with a reduced propagation rate, while the other was non-infectious. Furthermore, mutants with changes at the initiation codon of the coat cistron were prepared. An analysis of ribosome binding to such mutant RNAs revealed the importance of the A-U-G region for the formation of the initiation complex. With a similar approach applied to the beta-globin complementary DNA (CDNA) plasmid PbetaG, point mutations have been introduced at the positions corresponding to amino acids 121 to 123.

Lipid biosynthesis in the marine flatworm Convoluta roscoffensis and its algal symbiont Platymonas convoluta

As a part of an investigations on the lipid metabolism in Platyhelminthes, the acoel Convoluta roscoffensis, which harbors the green alga Platymonas convoluta as a symbiont, was studied. Isotopic tracer experiments established that the acoel lacks the ability to synthesize de novo long-chain saturated and unsaturated fatty acids and depends on its algal symbiont for these compounds. The acoel's fatty acid composition closely resembles that of the alga but differs from those of other animals; the acoel's polyunsaturated fatty acids are of the plant type (omega 3 family) rather than of the animal type (omega 6 family). The acoel also lacks the ability to synthesize sterols de novo. It contains 24-methylenecholesterol synthesized by the algae and, in addition, significant amounts of cholesterol, which is probably a host modification product of the algal sterol. With fatty acids provided by the symbiont, the acoel has the ability to synthesize its own complex lipids. The acoel contains relatively large amounts of triglyceride, phosphatidylcholine, and ethanolamine plasmalogen. These compounds are either not present at all or present only in minute amounts in the symbiotic alga. Since acoels belong to the most primitive forms of the present-day flatworms, the observed metabolic defects in this organism suggest that mechanisms for the biosynthesis of fatty acids and sterols were lost early during the evolution of the Platyhelminthes, and that this phenomenon is widespread within the phylum.

[Malabsorption syndrome during the initial phase of a case of severe rheumatoid purpura]

We report a case of severe Henoch syndrome in which the first manifestation was digestive with a prolonged and important intestinal malabsorption syndrome. The clinical, radiological and histological data allow to consider a malabsorption due to lesions of the chorion and submucosa probably secondary to the allergic vasculitis. The malabsorption syndrome, confirmed by the intestinal absorption tests, the study of which must be more systematic, seems to belong to the severe and polyvisceral forms of the Schönlein-Henoch syndrome.

Writing apparatus controlled by head movements for motor handicapped people

For a motor disabled person who cannot use his arms and hands we have constructed a device that enables him to operate a typewriter by means of head movements, via a forehead lamp. The text is first displayed on a picture screen and, after introducing any corrections, typed on a printer. This writing apparatus has been used very intensively for one year now, and evaluation laid down by the user himself has been included in the present paper. Several factors relevant to a large-scale application of this apparatus are discussed.