Partial regeneration of the above-elbow amputated rat forelimb. I. Innate responses.

Although a number of recent studies describe the facilitation of limb regeneration by electrical and other forms of stimulation, little is known of innate regenerative capacity in the mammalian limb. The present report describes spontaneous regenerative responses following subtotal forelimb amputation in the young white rat. In one group of animals the forelimb was amputated through the lower humerus and the skin sutured closed. In a second group, adjacent muscle tissue still attached to bone at its origin(s) was interposed between the cut surface of the humerus and the skin. Among animals of the first group (skin closure only) bone growth and limb regenerative responses were generally not observed. Animals of the second group displayed significant elaborations of cartilage and bone at the limb terminus. The appearance and subsequent modification of these tissues suggest that some capacity for limb regeneration exists innately in the young rat and can be more readily evoked than has been recognized heretofore. It is concluded that extant and forthcoming reports of electrically stimulated skeletal tissue growth, repair and regeneration among eutherial mammals should be examined to determine whether reported responses to stimulation represent advances beyond what might be expected from innate replacement processes alone.     

B.M.A. Planning Unit Survey of General Practice 1969

A postal survey of 776 principals representative of general practice in Britain is described. Doctors working in health centres are compared both with colleagues in other group practices and with doctors who have no group practice allowance. Young doctors are mainly in group practice, especially health centres; the proportion of doctors who are not in groups is diminishing steadily, and they are mainly older. With some notable exceptions health centres provide most space, equipment, and staff; group practitioners in privately-owned premises spend more of their money on their practices, more often use appointment systems, and tend to make more efficient use of premises and staff. Overall, however, the picture is still one of general practice geared to the needs of practitioners working alone. Premises with space for sophisticated organization and for future teaching needs are unusual.Scotland, the North of England, and Wales have fewer young doctors. Average lists are higher in the North of England, and less money is invested in practice premises.Young doctors look for modern premises and the tools and staff for the job. If their career expectations are to be met the tremendous improvements made in some practices must be extended rapidly to the remainder.     

Muscle reflex classification of low-back pain.

It has been well documented that low-back pain (LBP) patients have longer muscle response latencies to perturbation than healthy controls. These muscle responses appear to be reflexive and not voluntary in nature, and as a result, might be useful for objectively classifying LBP. The goal of the study was to develop an objective and accurate method for classifying LBP using a sudden load-release protocol. Subjects were divided into two groups: learning group (20 patients and 20 controls), and holdout group (15 patients and 12 controls). Subjects exerted isometric trunk force against a cable in four different directions. Following cable release, the trunk was suddenly displaced eliciting a muscle reflex response. Reflex latencies for muscles switching-on and shutting-off were determined using electromyogram signals from 8 trunk muscles. Independent t tests were performed on the learning group to determine which reflex parameters were to be entered into logistic regression analysis to produce a classification model. The holdout group was used to validate this classification model. The three-parameter model was able to correctly classify 83% of the learning group, and 81% of the holdout group. Using reflex parameters appears to be an accurate and objective method for classifying LBP.     

A proposed phylogeny of the flagellated protostelids.

The flagellated members of the group of mycetozoans known as protostelids have been recognized for some time to be members of a monophyletic group which also includes the myxomycetes. This inference was based primarily upon comparisons of the flagellar apparatus of the amoeboflagellate state. However, more detailed comparisons based on the whole life history and comparisons with an outgroup were necessary to have information sufficient to determine the interrelationships within the group. Recent studies of the other states of the life history of protostelids have provided a wealth of additional morphological and developmental characters such that an in depth phylogenetic analysis is possible. The results show that the group can be resolved into two major clades, one of which contains the myxomycetes and the myxomycete-like protostelid genera, Protosporangium, Clastostelium, and Ceratiomyxa, and another which contains the protostelid genera Planoprotostelium, Cavostelium, and Ceratiomyxella. As the myxomycetes appear to be part of the ingroup, and not a sister group to the protostelids, L.S. Olive's subclass Protostelia must be considered paraphyletic.     

Morphology of Bacteriophages of Lactobacillus bulgaricus, L. lactis and L. helveticus

Eleven virulent phages isolated from cheese or yoghurt factories and active on thermophilic lactobacilli used as starters were examined by electron microscopy. Five phages active on Lactobacillus bulgaricus belonged to Bradley's group B and can be divided into two groups with different host specificity. The three phages of the first group (two isolated in France, one in the USA) differ in size; the heads are either icosahedrons or octahedrons and the tails end in short-pronged base plates. The two phages of the second group, isolated in the USA. appear very similar. These are similar in length, have collars and octahedral heads. The non-contractile tails end in clusters of short fibres. An L. lactis phage, isolated in Finland, belongs to the same morphological group. It is similar in overall appearance to the two latter phages of the second group of L. bulgaricus , and there were numerous ghosts with polytails. Five phages. active on L. helveticus belong to Bradley's group A and may be divided into two groups with different host specificity. The first group contains a phage isolated in Finland. The second group is composed of four similar phages isolated in France. The Finnish phage is the largest, but the five phages show similar morphology. They have octahedral heads, firmly attached to the tails by connector devices, and they possess necks. The contractile sheaths have a helicoidal arrangement of hollow tubular subunits. They appear contracted either in a distal or a cervical position, revealing axial cores. Short tail fibres are probably present at the tail tip.     

Species 32. Cisticola Brachyptera. Pl. XVI.

What has been said about it in the introduction to the group leaves little necessary to say here of brachyptera s systematic position, but the following historical note relating to the bird's confusion with rufa will probably be useful.     

Eubacterial origin of chlamydiae.

The sequence of the 16S rRNA gene from Chlamydia psittaci was determined. Comparison of this sequence with other 16S rRNA sequences showed the organism to be eubacterial. The organism represents a hitherto unrecognized major eubacterial group. However, this group may be peripherally related to the planctomyces and relatives. Although these two groups seem to have very little in common phenotypically (they have been studied in very different ways), cell walls in both cases contain no peptidoglycan.     

Predation and the evolution of gregariousness. I. Models for concealment and evasion

The contribution of predation to the evolution of gregariousness is examined, and it is suggested that the needs of both predator and prey to conceal themselves and to detect the other may have been a major factor directing the development of social behaviour. This implies that it is important to consider the sensory capacities and the strategies open to both sides. Some relevant features of sensory detection are discussed and illustrated by an experiment on visual summation. These features are taken into account in devising two models for the interaction between predator and prey which allow the relative advantages of different dispersion patterns to be assessed. The first model assumes that the prey's main resource is concealment: it then appears that when detection will result in only one kill group formation is usually of advantage, but when the predator may destroy all or a proportion of a discovered group, it may be better to be solitary. A second model assumes that the prey have resources for evasion and defence. The occurrence of a kill will then be determined by priority of detection and under this constraint kill rate is lowered by group formation and falls with increasing group size.     

PAF-receptor. III. Conformational and electronic properties of PAF-like agonists and antagonists.

In order to compare electronic and conformational properties of PAF-agonists and PAF-antagonists, 14 analogues structurally related to PAF were studied. A common conformation of the glycerol backbone was present in all agonists and all constrained or flexible antagonists. The distinction between agonists and antagonists appears to be casted on position-2 where the folded conformation of the substituent for agonists should be the most probable. In position-3 the gauche conformation can be adopted by all the analysed compounds. The electrostatic potential well at -30 kcal/mol stretches to the carbonyl group in position-2 in the folded conformation of the agonists. On the contrary, in constrained antagonists, a second negative zone appears around the carbamate group. Given the modelling results, the triethylammonium PAF analogue considered in literature as a weak agonist, was resynthesized and proved to be more potent than previously reported. These experimental results confirm our hypothesis in terms of a common conformation of agonist and antagonist PAF-like molecules.     

Localization of unpaired electrons in molecules of lysozyme substrate-inhibitors. I. N-acetylglucosamine]

Electron structure of N-acetylglucoseamine molecule and its ion-radicals has been studied by quantum-chemical methods CNDO2 and JNDO, and by ESR as well. N-acetyl group is shown to be the only electron acceptor group of AGA molecule. Phototransformations of paramagnetic centres are studied at different pH values.     

Rat intestinal trehalase. Studies of the active site.

Rat intestinal trehalase was solubilized, purified and reconstituted into proteoliposomes. With octyl glucoside as the solubilizing detergent, the purified protein appeared as a single band on SDS/polyacrylamide-gel electrophoresis with an apparent molecular mass of 67 kDa. Kinetic studies indicated that the active site of this enzyme can be functionally divided into two adjacent regions, namely a binding site (with pKa 4.8) and a catalytic site (with pKa 7.2). Other findings suggested that the catalytic site contains a functional thiol group, which is sensitive to inhibition by N-ethylmaleimide, Hg2+ and iodoacetate. Substrate protection and iodoacetate labelling of the thiol group demonstrated that only a protein of 67 kDa was labelled. Furthermore, sucrose and phlorizin protected the thiol group, but Tris-like inhibitors did not. Structure-inhibition analysis of Tris-like inhibitors, the pH effect of Tris inhibition and Tris protection of 1-(3-dimethylaminopropyl)-3-ethylcarbodi-imide inactivation permitted characterization and location of a separate site containing a carboxy group for Tris binding, which may also be the binding region. On the basis of these findings, a possible structure for the active site of trehalase is proposed.     

Recognition of Morganella subspecies, with proposal of Morganella morganii subsp. morganii subsp. nov. and Morganella morganii subsp. sibonii subsp. nov.

The genus name Morganella was established within the family Enterobacteriaceae in 1978. Morganella morganii is the only species described thus far within this genus, and the name M. morganii has been accepted by usage in the scientific community for strains previously known as Proteus morganii. M. morganii isolates differ in their abilities to ferment trehalose and exhibit variable lysine and ornithine decarboxylase patterns, emphasizing the phenotypic heterogeneity within this species. Previous genetic studies failed to reveal separate entities within the genus Morganella. We observed some trehalose-fermenting strains with different lysine and ornithine decarboxylase patterns. Two strains were lysine and ornithine positive, 3 were lysine positive and ornithine negative, and 29 were lysine negative and ornithine positive. These strains and 25 non-trehalose-fermenting strains with different lysine and ornithine decarboxylase patterns were investigated. DNA-DNA hybridization studies and phenotypic characterizations revealed that M. morganii can be separated into three DNA relatedness groups and seven biogroups. Strains from DNA relatedness group 1 were trehalose negative, and strains from DNA relatedness groups 2 and 3 were trehalose positive. One biogroup from DNA relatedness group 2 was phenotypically indistinguishable from DNA relatedness group 3. On the basis of these studies, we propose that M. morganii be subdivided into M. morganii subsp. morganii (type strain ATCC 25830) containing biogroups A, B, C, and D (DNA relatedness group 1) and M. morganii subsp. sibonii (type strain 8103-85; = ATCC 49948) containing biogroups E, F, and G (DNA relatedness groups 2 and 3).     

Isatin-enzyme interactions. VI. Inhibition of rat kidney alkaline phosphatase.]

Interaction of isatin with rat kidney alkaline phosphatase has been studied. Mode of attachment of isatin with the enzyme protein is most likely through amino group(s), which is also imperative for catalysis. Sulphydryl group(s) do not seem to be involved in enzyme action. Zinc is also needed for enzyme activity. Use of sulphydryl compounds suggests that isatin inhibition of the enzyme is through attachment at the metal site. However, this inhibition may not only be due to simple chelation of the metal by isatin.     

Conformational studies of sphingolipids by NMR spectroscopy. II. Sphingomyelin

Sphingomyelin (SM) is the most prevalent sphingolipid in the majority of mammalian membranes. Proton and 31P nuclear magnetic resonance spectral data were acquired to establish the nature of intra- and intermolecular H-bonds in the monomeric and aggregated forms of SM and to assess possible differences between this lipid and dihydrosphingomyelin (DHSM), which lacks the double bond between carbons 4 and 5 of the sphingoid base. The spectral trends suggest the formation of an intramolecular H-bond between the OH group of the sphingosine moiety and the phosphate ester oxygen of the head group. The narrower linewidth and the downfield shift of the resonance corresponding to OH proton in SM suggest that this H-bond is stronger in SM than in DHSM. The NH group appears to be involved predominantly in intramolecular H-bonding in the monomer. As the concentration of SM increases and the molecules come in closer proximity, these intramolecular bonds are partially disrupted and the NH group becomes involved in lipid-water interactions. The difference between the SM and DHSM appears to be not in the nature of these interactions but rather in the degree to which these intermolecular interactions prevail. As SM molecules cannot come as close together as DHSM molecules can, both the NH and OH moieties remain, on average, more intramolecularly bonded as compared to DHSM.     

A theory of natural selection incorporating interaction among individuals. VII. Use of groups consisting of one sire and one dam

A previous study, (V), in this series dealt with the problem of interaction among individuals in a population by utilizing a conceptual life-history model that assumed the synchronization of fitness components (viability and fecundity) for members within groups of interacting individuals. The model also assumed that the group members were not differentiated in any way. It was shown that these assumptions of synchronization and homogeneity of group members resulted in overall symmetric fitness values, and that selection operating on these symmetric values produced optimum short- and long-term results.Since the idealized model of paper (V) yields optimum selection results, it is of interest to consider specific biological mechanisms which can be used to fulfill the conceptual assumptions involved. The solution adopted in this study is to, first, require survival to occur at the group level. This forces the viability parameters to be identical for all group members.Second, the group composition is restricted to a single pair mating. This forces the fecundity parameters to be identical for members (sire and dam) of the same group. However, this solution causes a complication. Since each individual is identified as belonging to one of the two sexual types, it is necessary to extend the previous analysis in paper (V), to accommodate differentiated group members. It is shown that this differentiation leads to a non-symmetric fitness matrix. However, it is further shown that the selection results can be obtained by use of a ‘combined’ fitness matrix that is symmetric. Therefore, the important result is demonstrated that selection involving differentiated sire-dam groups possesses all of the optimum short- and long-term properties inherent in the original non-differentiated selection procedure developed in paper (V). It is speculated that these results could be of some significance with regard to the evolution of a monogamous, pair-bonding family structure.     

Conformational studies of sphingolipids by NMR spectroscopy. I. Dihydrosphingomyelin

The conformational features of dihydrosphingomyelin (DHSM), the major phospholipid of human lens membranes, were investigated by 1H and 31P nuclear magnetic resonance spectroscopy. Several postulates emerge from the observed trends: (a) in partially hydrated samples of DHSM in CDCl3 above 13 mM, at which lipid-lipid interactions prevail, the amide proton is mostly involved in intermolecular H-bonds that link neighboring phospholipids through bridging water molecules. In the absence of water, the NH group is involved in an intramolecular H-bond that restricts the mobility of the phosphate group. (b) In the monomeric form of the lipid molecule, the amide proton of the major conformer is bound intramolecularly with one of the anionic and/or ester oxygens of the phosphate group. A minor conformer may also be present in which the NH proton participates in an intramolecular H-bond linking to the OH group of the sphingoid base. (c) Complete hydration leads to an extension of the head group as water molecules bind to the phosphate and NH groups via H-bonds, thus disrupting the intramolecular H-bonds prevalent at low concentrations.     

Proposal of Corynebacterium propinquum sp. nov. for Corynebacterium group ANF-3 strains

Abstract Chemotaxonomic and genomic studies were performed on seven Corynebacterium group ANF-3 strains isolated from human sources. All these strains possess cell wall component type IV ( meso -diaminopimelic acid, arabinose and galactose), corynemycolic acids and a G+C content of DNA of 57 to 59 mol%. These results confirm that they can be placed in the genus Corynebacterium . Six of these strains were found to constitute a tight hybridization group distinct from named Corynebacterium species or related organisms. This genomic group constitutes a new species which can be identified within the genus Corynebacterium by ribotyping or phenotypic tests and for which the name Corynebacterium propinquum is proposed. The type strain is strain B 77159 (= Collection of the Institut Pasteur CIP 103792).     

Experimental study of results of nerve suture under tension vs. nerve grafting.

Evoked electromyograms and myelinated fiber caliber histograms were used to compare the results of end-to-end nerve suture and nerve grafting, performed with an operating microscope. The best results were achieved after direct suture without tension. Direct suture under a tension of 25 grams produced results sometimes comparable the that of the zero tension group, but mostly quite inferior to those and even to the grafted group. The regeneration of axons in the nerve graft group was delayed more than in the sutured groups, but by the tenth month the number of regenerating fibers had increased with stable and comparatively good results. After a nerve suture under a tension of 25 grams, there is impairment of the blood flow at the suture site, and the results are not as good. In such situations I believe nerve grafting should be performed. This amount of tension also seems to be the limit which will allow accurate coaptation of a nerve by microsurgical techniques.