Chromatographic comparisons of heterotic rat liver histones. Chromatographic comparisons of histones isolated by acid extraction of liver chromatin preparations from F344 inbred rats and their paternal heterotic F344 X H hybrid progeny reveal the presence of a number of age-and line-specific nonhistones also extractable in acid. The patterns of the core histones (H2A, H2B, H3, and H4) remain relatively constant during development, while histone H1 shows unusual chromatographic properties in the 30- and 35-day hybrid preparations. In general, the complexity of the nonhistone fraction decreases as the animal ages. Such variations may be a reflection of a prelude to altered genetic activity in organisms undergoing growth and development at different rates, and may have significant implications for transcriptional processes.


Phaeomelanin synthesis and obesity in mice. Interaction of the viable yellow (Avy) and sombre (eso) mutations. Is abnormal regulation of phaeomelanin synthesis, which results in yellow coat color, inextricably linked to the development of obesity in viable yellow (Avy) house mice? To answer this question, black male mice of genotypes Avy/A eso/e+ and A/ae eso/e+ were produced from (DFT/Wf X C3H-1 vyfB/HeWf X SO/LeWf matings. The sombre (eso) mutation prevents phaeomelanin synthesis; therefore, all mice carrying this dominant allele are black regardless of the alleles present at the agouti locus. These black males were weighed weekly to 18 weeks of age. Simultaneously the agouti locus genotype of each male was determined by test matings to a/a e+/e+ females. The results of these test matings indicated that the two genotypes could be classified rather accurately by the intensity of pigmentation of the belly hair. Black Avy mice tended to have more dilute belly pigmentation that black A/ae mice. These gross observations were confirmed by microscopic examination of several hair types. Black Avy males reached a mean body weight of 44.2 +/- 0.6 g at 18 weeks, while black A males had a mean weight of 30.7 +/- 0.4 g at the same age. It is concluded that excessive weight gain resulting in obesity is induced by the Avy gene even when phaeomelanin synthesis is completely inhibited.


G-band patterns, hemoglobin, and transferrin types of the bharal: chromosomal evolutionary relationships with sheep and goats. G-band patterns of the bharal (Pseudois nayaur), 2n = 54, were compared with those of wild sheep (Ovis dalli stonei), 2n = 54, and the Persian wild goat (Capra hircus), 2n = 60. Patterns of the longer segments of the biarmed chromosomes of Pseudois were similar to those of the longer biarmed segments of Ovis, whereas the shorter segments differed. Biarmed chromosomal segments had G-band homologies with specific acrocentric autosomes of Capra and were ranked as follows in descending order of relative lengths: Pseudois 1:4/13; 2:1/27 and 3:3/29; and for Ovis 1:1/5; 2:3/10 and 3:4.9. Arm ratios and relative lengths of the biarmed chromosomes were compared. The Y chromosome of Pseudois is a small biarmed chromosome that resembles those of Capra and Ovis. Hemoglobin B was observed in the bharal and was indistinguishable from Hb B of Ovis using starch-gel electrophoresis. The transferrin "zone pair" of Pseudois migrated more slowly in starch-gel electrophoresis than do any of the known transferrin types in sheep and goats. We refer to this transferrin as Pseudois Tf A. The biarmed formations of Pseudois and Ovis are discussed in relation to karyotype evolution and possible speciation.


[Classification of oral contraceptives and its practical application to choice of prescriptions]. The authors have tried to classify the oral contraceptives at present in use throughout the world by their respective levels of oestrogenic and progestogenic components, taking into consideration also the relative strength of each product in use. They have based this classification on their personal experience of the several oral contraceptive products and on a profound study of the international literature. In this way it is possible to define a place for each oral contraceptive so that it can be chosen for the best possible use of a particular product for the hormonal background of the person using the contraceptive. It is true that changes have to be made to work out the oral contraceptives used for masses of people, but on the other hand in countries where there is sufficient medical personnel and education so that it is possible to think out and to prescribe for an individual, it seems to us useful that the doctor who is prescribing should try to adjust the oral contraceptive to the hormonal climate of the woman seeking it. This is true not only for the first time a prescription is made but in cases where by the accident of failure to tolerate the product something must be done to correct the troubles that are so often found in the first months after starting to use contraceptive products. This study includes a general picture of all oral contraceptives in which the products have been classified according to the total dose of oestrogens administered and according to the proportions of progesterone to oestrogens which make up the hormonal climate of the product. On the other hand this study also includes a list of the observations to make in order to adapt the oral contraceptive to the side-effects shown after the first prescription. The authors have come to the conclusion that by adapting the choice of a particular oral contraceptive to the woman who is to receive it interruptions in taking the contraceptive because of side-effects should be avoided. So unwanted pregnancies will be avoided and also the termination of these unwanted pregnancies.


Effect of rabbit strain on activity level and cytotoxicity of serum complement. II. Comparison of five murine target cells. Serum samples from about 10 males and 10 females from each of 15 genetically defined strains of rabbits and from one hybrid were tested as sources of complement for the microtiter lymphocytotoxicity test using as target cells lymph node cells from C3H/HeJ, B10/Sn, BALB/cJ, and DBA/2J strain mice. The lynph node cells were tested with appropriate H-2 alloantisera. Results indicated marked strain differences. Correlation analysis of these data with data using primarily aliquots from the same serum samples tested against lymph node cells from B10.A/Sn mice showed clearly that a genetically defined population of rabbits that provided serum of high quality for one of these test systems would in general work reasonably well in any one of the other four. The correlation coefficients in all possible combinations ranged from +0.49 to +0.92. Of the five strains tested, the results obtained from BALB/cJ appear to be the best predictors of the results in the other four strains (r values were +0.74, +0.57, "0.76, and +0.92). Studies are in progress to test rabbit serum complement samples against the more demanding tumor cells.


Mus musculus x Mus caroli hybrids: mouse mules. Analysis of six enzymes using starch gel electrophoresis indicates that autosomal and X-linked genes of both parental species are expressed normally in M. musculus X M. caroli hybrids. There is no evidence for allelic repression for the four autosomally inherited enzymes. Banding patterns for G6PD and PGK-1 indicate that X-chromosome inactivation occurs and that the maternally derived M. musculus X-chromosome is preferentially expressed in the yolk sac. Despite normal genetic expression none of the four adult female hybrids was fertile and the male hybrids tended to be retarded during fetal development. The routine production of fetal M. musculus X M. caroli hybrids, heterozygous for three X-linked genes coding for G6PD, PGK-1, and HPRT, should provide an excellent system for the analysis of X-chromosome expression and an alternative to the mule for studies of hybrid reproduction and development.


Increased stability of a hybrid molecule. The spectrophotometric assay of serum ADH of the quail-chicken hybrid shows, after thermal denaturation carried out at 50 degrees C, a greater residual activity that that of either parental serum; such increased resistance to heat reflects a greater stability of the hybrid molecule.


Feedback control by the testis of gonadotrophin secretion: an examination of the inhibin hypothesis. Spermatogenesis in rats was interrupted by local X-irradiation, heat or ligation of the testicular efferent ducts. A significant and specific rise in the serum level of FSH occurred 5--8 days after ligation of the efferent ducts, reaching twice the value observed in sham-operated controls by 21 days after the operation. After the testes were heated to 43 degrees C for 30 min, the serum levels of both LH and FSH were raised within 3 days and remained so up to 50 days after treatment. After X-irradiation, no changes in the concentration of FSH were observed in the first 21 days after treatment, but the serum levels of both gonadotrophins were increased at 49 days. By comparing the relative increases in the concentrations of FSH and LH after germ cell damage with those occurring after castration, it was evident that testicular androgens could account for only part of the normal feedback control of FSH secretion; at least one third of the inhibition of FSH secretion appeared to be due to non-androgenic sources, presumably 'inhibin'.


Dependence of glutamine metabolism and ammonia synthesis on sex in rat kidney slices. The uptake and metabolism of glutamine, production of ammonia and consumption of O2 were studied in kidney slices isolated from mature, gonadectomized and newborn male and female rats in the presence of 0.05, 0.5, 2 and 5 mM-glutamine. Slices isolated from mature intact female rats showed significantly greater conversion of glutamine into CO2 and NH3 without any change in the total uptake of glutamine when compared with all other experimental groups. No difference in O2 consumption was found between mature male and female animals. Ovariectomy reduced glutamine metabolism, NH3 production and O2 consumption without any effect on the total uptake of glutamine. In contrast, castration did not significantly affect glutamine metabolism and production of NH3 but did reduce O2 consumption. Newborn (20- to 21-day-old) rats showed no sex-dependent differences in glutamine uptake and metabolism, production of NH3 and consumption of O2, but values for all these parameters were lower in kidney slices from newborn animals than in kidney slices from mature, intact or gonadectomized male and female rats. It is concluded that in female rats, metabolism of glutamine and production of NH3 may be influenced by ovarian sex hormones.


Effect of growth hormone on the metabolism of 25-hydroxycholecalciferol in hypophysectomized rats on a diet without vitamin D and low in calcium. The metabolism of 25-hydroxycholecalciferol (25-(OH)D3) was investigated in rats fed a diet low in calcium and without vitamin D for 4 weeks after hypophysectomy. Compared with intact rats on the same diet these animals had a low serum phosphorus concentration, a less marked degree of hypocalcaemia and their parathyroid gland was not hypertrophied. Eighteen hours after i.p. injection of a single dose of tritiated 25-(OH)D3, chromatography of serum extracts on Sephadex LH-20 showed that the percentage of radioactivity corresponding to 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) was lower in hypophysectomized rats than in control rats. High-pressure liquid chromatography demonstrated that 81% of this material had the same elution profile as 1,25-(OH)2D3. The percentage of 1,25-(OH)2D3 in the serum of hypophysectomized rats could be increased to the level seen in the controls by chronic treatment with bovine growth hormone. This action of growth hormone was most probably independent of the parathyroid glands since the injection of parathyroid extract did not alter 25-(OH)D3 metabolism in hyophysectomized animals. These results suggest that the decrease in the conversion of 25-(OH)D3 to 1,25-(OH)2D3 after hypophysectomy may be related to the lack of growth hormone.


The importance of prolactin for lactation in the ewe. The effect of 2-bromo-alpha-ergocryptine (bromocriptine) on the induction, initiation and maintenance of milk secretion was studied in post-parturient ewes and in ovariectomized ewes artificially induced to lactate by treatment with oestrogen plus progesterone and then dexamethasone. Treatment with bromocriptine (about 0.4 mg/kg every 3 days) lowered and maintained the plasma concentration of prolactin at less than 12 ng/ml. Ewes receiving bromocriptine concurrently with oestrogen plus progesterone during the priming phase had a significantly lower (P less than 0.05) mean cumulative milk yield than control ewes, although the milk of the treated ewes contained normal amounts of fat, protein and lactose. Administration of bromocriptine during dexamethasone-induced lactogenesis had no significant effect on the mean cumulative milk yield but significantly (P less than 0.05) increased the milk fat and protein content. In established lactation, bromocriptine markedly reduced the milk yield in both intact and ovariectomized ewes. The concentration of protein was not significantly affected although the milk fat content was higher in the bromocriptine-treated than in the control ewes. The effects of bromocriptine on milk yield and composition during galactopoiesis could be reversed by concurrent infusion of prolactin and the results suggest that prolatin is an important hormone during mammogenesis and galactopoiesis in the sheep.


Evidence for specific progesterone receptors in rat brain cytosol. Cytosol prepared from rat brains perfused with saline possesses saturable macromolecular components which form unstable complexes with [3H]progesterone in vitro. The components can be distinguished from the serum protein corticosteroid-binding globulin (CBG) which also binds progesterone. Unlike CBG, the cytosol components did not bind corticosterone and were more unstable in the presence of Sephadex LH-20 than was CBG. Furthermore, the components were precipitated by a concentration of ammonium sulphate in which CBG is soluble. Unlabelled progesterone and testosterone competed equipotently with [3H)progesterone, and 5 alpha-pregnane-3,20-dione and deoxycorticosterone competed to a lesser extent, whereas oestradiol, corticosterone and 11 beta-hydroxy-pregn-4-en-3,20-dione were not bound. Although present in all brain tissues examined and in uterine and anterior pituitary tissue, the saturable binding was not detectable in cytosols from the spleen or diaphragm. Complete exchange occurred in the incubation at 0 degrees C between [3H)progesterone and unlabelled progesterone and the saturable binding sites and the reaction attained apparent equilibrium within 2 h at this temperature. An incubation temperature of 30 degrees C resulted in an almost complete loss of saturable binding. Scatchard plots obtained from binding isotherms were curvilinear and yielded at least three dissociation constants (Kd), two of higher affinity (Kd congruent to 10(-8) mol/l) and one about sixty times lower. From these results it is concluded that rat brain cytosol possesses progesterone-selective components which fulfil some of the criteria required for steroid hormone receptors.


Effects of active immunization of female rabbits against testosterone. Prepubertal (immature) and mature female rabbits were actively immunized against testosterone-3-oxime-bovine serum albumin over a period of 11 weeks. The antibody titre was significant in all animals by 5 weeks. The concentration of FSH in prepubertal animals decreased significantly (P less than 0.001) between weeks 1 and 5, but no significant changes were observed in the concentration of LH at any time. After immunization for 8 weeks, there was a significant (P less than 0.05) increase in the serum concentration of androgen and the percentage of bound testosterone also increased (P less than 0.05). The serum concentration of oestradiol increased after immunization for 11 weeks, compared with values at 8 weeks (P less than 0.05) and oestradiol binding also rose by week 5 (P less than 0.01). Libido was not affected and significantly (P less than 0.005) increased numbers of ovulations were noted in immunized animals. These results suggest that immunization of the female rabbit against testosterone may disrupt the normal regulation of follicular maturation.


Radioimmunoassay of 3,3'-di-iodothyronine in unextracted serum: the effect of endogenous tri-iodothyronine. The development of a highly sensitive and specific radioimmunoassay for 3,3'-di-iodothyronine (3,3'-T2) is described. The assay was applied to the measurement of 3,3'-T2 in unextracted human serum and used 8-anilino-1-naphthalene-sulphonic acid to inhibit the binding of 3,3'-T2 to serum transport proteins. The lower limit of detection of the assay was 2 fmol 3,3'-T2 per tube, which corresponded to 10 pmol 3,3'-T2/l serum. The mean concentration of 3,3'-T2 in normal serum was found to be 23 pmol/l, which is considerably lower than most values reported previously. Evidence is presented which suggests that the cross-reactivity of tri-iodothyronine with the antiserum to 3,3'-T2 is an important factor in the measurement of serum concentrations of 3,3'-T2 by radioimmunoassay.


Generation of somatomedin activity in response to growth hormone and insulin from isolated perfused livers of normal and protein-malnourished rats. The generation of somatomedin activity by isolated perfused livers was examined in protein-malnourished (4% casein diet) and well-nourished (controls, 20% casein diet) rats. There was significantly less somatomedin activity (measured by the porcine costal cartilage bioassay), after perfusion for 2 h, in the perfusates from the livers of malnourished rats both in hormone-free perfusates and perfusates containing hormones (10 microgram GH/ml, 1000 microunits insulin/ml or a combination of the two). A reduction in the somatomedin activity generated by the liver may be the mechanism responsible for the low serum level of somatomedin (in spite of raised or normal levels of growth hormone) in human or experimental protein malnutrition.


Radioimmunoassay of arginine-vasopressin in human urine and its use in physiological and pathological states. A highly specific radioimmunoassay for arginine-vasopressin (AVP) in human urine has been developed, with a detection limit of 2.2 fmol/ml. The mean recovery of added AVP was 99.5 +/- 3.1 (S.D.)% when correction was made for the fact that an inverse relationship was observed between the recovery of AVP and the osmolality of the urine. The intra- and interassay coefficients of variation were 3.5--7 and 2.5--10% respectively. Arginine-vasopressin remains stable in urine after repeated freezing and thawing after storage at 4 or 20 degrees C for up to 7 days and at -20 degrees C for more than 3 months. During unrestricted fluid intake in normal people, the mean rate of renal excretion of AVP was 95 +/- 68 (S.D.) fmol/min. An isosmotic reduction of 9% in the plasma volume increased the excretion of AVP to 259 +/- 147 (S.D.) fmol/min. At the height of water-induced diuresis the rate of excretion fell to 70 +/- 28 (S.D.) fmol/min. Fluid deprivation for 18 h produced a moderate but significant increase in mean excretion of AVP, to a value of 116 +/- 67 (S.D.) fmol/min. Patients with compulsive water drinking showed a normal relationship between urine osmolality and the rate of excretion of AVP. In pituitary diabetes insipidus, AVP was undetectable, whereas in hereditary nephrogenic diabetes insipidus a progressive increase in the rate of excretion of AVP was observed in response to dehydration. There was a wide variation in the rate of excretion of AVP (range 126--8704 fmol/min) in patients with unexplained hyponatraemia, presumed to be due to an inappropriate secretion of antidiuretic hormone. Despite this variation, the relationship between urine osmolality and the rate of excretion of AVP clearly differed from that observed in normal people.


'Transdifferentiation' of chicken neural retina into lens and pigment epithelium in culture: controlling influences. The in vitro transdifferentiation of chicken embryo neural retina into pigment epithelium and lens cells was investigated under a variety of experimental conditions. Our findings suggest that some aspects of the phenomena are a function of medium composition and volume, whereas others depend upon conditions which develop during culture growth. Before melanin is visible, potential pigment cells are recognized as foci within epithelial sheets which remain in contact with the dish. The final area occupied by colonies of potential pigment cells is directly proportional to bicarbonate concentration. Low total medium volume also favours formation of potential pigment cells. In contrast the extent of cells other than potential pigment cells is not related to bicarbonate and is favoured when the volume of medium is large. Accumulation of melanin within the potential pigment cell colonies is suppressed when cells are crowded together. Lentoid bodies are formed from cells which are distinct from potential pigment cells and arise in crowded situations, in association with multilayering. Another type of structure superficially resembling a lentoid is derived from cell aggregates formed during the initial establishment of cultures. The survival of these 'aggregate bodies' is inversely related to bicarbonate concentration. Crystallin content is unrelated to lentoid numbers. The results provide the basis for a new hypothesis concerning cytodifferentiation in this system.


Interaction between inner cell mass and trophectoderm of the mouse blastocyst. I. A study of cellular proliferation. Increase in cell number has been compared with mitotic activity in the polar and mural trophectoderm and in the inner cell mass (ICM) of mouse blastocysts. The results indicate that whereas ICM cells divide at a rate which is compatible with the rate of increase of ICM cell number, polar trophectoderm cells divide faster and mural trophectoderm cells slower than can account for their own rates of cell number increase. It is suggested that the ICM induces a high rate of proliferation in the polar trophectoderm and that there is a resulting cell shift from polar to mural regions during blastocyst development. Mural trophectoderm cells close to the ICM divide faster than those farther away, indicating that cells may retain a 'memory' of ICM contact for some time after leaving the ICM. There is considerable cell death in the blastocyst, but this is restricted to a short period of time coincident with the appearance of primitive endoderm.


In vitro studies of mouse embryos bearing mutations in the T complex: t6. Cultured blastocysts homozygous for the t6 mutation lose their inner cell mass within a few days of attachment to the culture dish. At about the same time it becomes apparent that putative t6-mutant trophoblast cells and their nuclei fail to enlarge to the degree of their normal counterparts. These abnormalities in mutant embryos are reflected by an abrupt drop on the seventh equivalent gestation day in the rate of increase of beta-glucuronidase activity. The failure of t6/t6 trophoblast nuclei to enlarge normally appears to be due partially to endoreduplication at a slower rate than normal trophoblast nuclei and partially to premature cessation of DNA synthesis. Analyses indicate that this abnormality is not reversed when mutant embryos are placed in chimeric association with normal ones. Trophoblast outgrowths from mutant and normal trophectodermal vesicles are similarly distinguishable by differences in outgrowth and nuclear size as well as DNA content and synthesis. Despite the fact that t6/t6 embryos and trophectodermal vesicles are phenotypically different from normals from early times in culture, the trophoblast cells in the mutant structures acquire and continue to produce two enzymes characteristic of trophoblast differentiation, delta 5, 3 beta-hydroxysteroid dehydrogenase and plasminogen activator. On the basis of these and previous observations, we propose that the primary effect of the t6 mutation is to cause a metabolic lesion which kills inner cell mass cells relatively quickly but which has a more gradual effect upon trophoblast cells. The fact that phenotypically recognizable t6/t6 trophoblast cells can survive for several days before dying makes this a potentially useful system in which to search for the t6 gene product(s).


Participation of the cell surfaces determining the developmental courses in the cellular slime mould dictyostelium purpureum. Dictyostelium purpureum S5 and S6, mating type strains, form fruiting-bodies in a monoclonal culture, but product macrocysts in a mix culture. The effects of Concanavalin A (Con A) on both fruiting-body formation and macrocyst formation, and changes of Con A-mediated cell agglutinability during development were studied. It was found that Con A inhibits macrocyst formation but not fruiting-body formation, and that macrocyst-forming cells are much more susceptible to Con A agglutination than are fruiting-body-forming cells during the aggregation stages. When fruiting-body-forming cells are treated with either trypsin or alpha-chymotrypsin, their Con A agglutinability is enhanced to the same extent as that of macrocyst-forming cells. It was also found that when S6 cells are treated with proteases they sometimes produce normal macrocysts even in a monoclonal culture. The results obtained in these experiments showed that the surface properties of fruiting-body-forming cells and macrocyst-forming cells are different, and that the cell surface might play an important role in determining the two developmental courses.


Cell adhesion and chondrogenesis in brachypod mouse limb mesenchyme: fragment fusion studies. This study is a continuing investigation of the effect of the brachypod mouse mutation on cell interactions and chondrogenesis during early limb development. In this report, cell adhesiveness was assessed in fused fragments of brachypod and normal limb-bud mesenchyme. Examination of the interface of fused distal postaxial limb fragments show brachypod limb mesenchyme to be more adhesive than normal limb mesenchyme. Chondrogenesis within brachypod fragments is delayed and less extensive than in normal fragments. In addition, chondrogenesis within normal fragments is not affected by the juxtaposition of the brachypod fragment, and vice versa.


Neurotrophic control of the cell cycle during amphibian limb regeneration. It is shown here that amputated and denervated limbs of larval axolotls dedifferentiate and a proportion of the cells released undergo DNA synthesis and mitosis. When the limb is denervated prior to amputation fewer cells go through the cell cycle, implying the existence of a pool of trophic factor in the limb. Recent work has demonstrated that denervated blastemal cells accumulate in the G1 phase of the cycle. These results strongly argue against the theory that the trophic factor controls the G2 phase. Rather, it is proposed that this factor regulated either the total number of cells cycling or the rate at which they cycle by varying the length of the G1 phase.


Acetylcholinesterase- and norepinephrine- containing nerves in developing rat lung. The lungs of rat fetuses at various stages of gestation and lungs of infant rats were examined histochemically for acetylcholinesterase (AChE) and norepinephrine (NE). No AChE is present in the fetal lungs until 15 days of gestation. At this stage a number of large round cells appear which stain heavily for AChE. These cells disappear by the 18th day of development and at 18 days no AChE-positive structures are demonstrable within the lung. The large AChE-positive cells are of similar size and distribution to fluorescent cells which become apparent after treatment of the mothers with L-DOPA. At 20 days, the day before delivery, a diffuse AChE reaction appears in the walls of large branches of intrapulmonary bronchi. At 20 days, also, sparse NE-containing nerves are present near the hilum and extend along bronchial arteries into the lung. Not until birth do AChE-containing nerves appear in intrathoracic structures. These are vagal preganglionic and postganglionic fibers near the trachea, bronchi, and esophagus. AChE-positive ganglion cells are present in the walls of extrapulmonary bronchi at birth, and perimuscular nerve plexuses containing AChE are also present in the bronchial walls. NE-containing nerves are visible in several divisions of the bronchial artery at birth. Three days postnatally, AChE-containing nerves have not yet invaded intrapulmonary structures, but at this stage the adult pattern of adrenergic innervation is present. By the fifth postnatal day, sparse AChE-positive nerves are associated with intrapulmonary bronchi, and rats 9 days old present the adult pattern of cholinesterase-containing nerves.


Regional differences in the morphology and motility of mesodermal cells from the early wing-bud of normal and talpid3 mutant chick embryos. A method of culturing has been employed to compare the properties of cells migrating from small mesodermal explants taken from different regions of normal and mutant limb-buds at different stages of development. An analysis by time-lapse cinematography of the morphology and mobility of cells migrating from explants defines a distal region within the limb-bud where these properties are distinct from those of cells from more proximal regions. In the normal wing-bud distal cells subjacent to the apical ectodermal ridge possess a characteristic multipolar morphology and translocate slowly in vitro. Cells from more proximal regions tend to be bipolar and translocate more rapidly. Distal and proximal cells also probably differ in their adhesive strengths. In the mutant, talpid3, distal and proximal cells do not differ in the above properties and cells from all regions of the limb-bud are multipolar, translocate slowly and are more adhesive than normal cells. A study of light micrographs and scanning electron micrographs suggests that these regional differences are found in the limb-bud in vivo and are not merely an effect produced by the in vitro culturing system.


Scanning electron microscopy of cells isolated from amphibian early embryos. Cells have been dissociated from Xenopus and Ambystoma late blastulae, allowed to adhere to glass coverslips, and studied by scanning electron microscopy. Xenopus ectoderm cells initially show filopodia; later larger single pseudopodia are formed. Ambystoma ectoderm cells show fewer filopodia than Xenopus ectoderm, but later form pseudopodia. Ectoderm cells of both Xenopus and Ambystoma show links between adjacent cells. Xenopus endoderm cells do not show filopodia initially, but later show large pseudopodia.


The effect of retinoic acid on chondrogenesis in the fetal hamster tibia in vivo. Chondrogenesis in the fetal hamster tibia was examined 24, 36 and 48 h after maternal administration of retinoic acid at a known teratogenic dose (80 mg/kg) on day 10 of gestation. Twenty-four hours after treatment the tibial chondroblasts were more closely packed with less intervening fibrillar or granular matrix than in the controls. By 36 h post treatment, an intercellular matrix containing wide clumped fibrils unassociated with matrix granules had begun to accumulate, while the condroblasts had a relatively poorly developed Golgi apparatus and smooth, non-scalloped cell outlines. Cells frequently maintained contact chondroblasts appeared similar to controls of the same age. It is suggested that the paucity and abnormality of the extracellular matrix prevents the chondroblasts from assuming their normal spatial relations with each other, resulting in a small skeletal blastema.


Facial development in the mouse; a comparison between normal and mutant (amputated) mouse embryos. This work extends previous investigations into cell interactions involved in specific morphogenetic events during the development of normal and mutant (amputated) mouse embryos. In the mutant mesenchyme, cells tend to clump together and form far more extensive areas of cell contact than are found in normal mesenchyme. This is confirmed for mutant facial mesenchyme. Facial outgrowth in the mutant is retarded. The first stages of this abnormality can be seen in the naso-frontal region at 10.5 days after conception. Neither the quantity of cells contributing to naso-frontal outgrowth nor cell proliferation in the naso-frontal region differ from normal in the mutant, and these factors can be eliminated as causes of the anomaly. Instead, cell clumping and increased areas of contact in the mutant arrest the normal expansion of the naso-frontal mesenchyme which presumably occurs as a result of increased secretion of intercellular matrix material between 9.5 and 10.5 days of development. The importance of this early expansion phase for facial development has not previously been recognized.


Patterns of cellular proliferation during thyroid organogenesis. The changes in rate and location of cellular proliferation were analyzed to determine if localized areas of cell division were influencing shape changes in the chick thyroid. Pulse labeling with tritiated thymidine indicates that the gland's labeling index declines throughout its development. Initially, the thyroid placode has a lower labeling index than the neighboring pharyngeal epithelium. An evaluation of the positions of pulse-labeled cells reveals that the evaginating thyroid grows by annexing cells from the pharyngeal epithelium. The older evaginated regions of the gland exhibit the lowest labeling indices. The newly acquired regions still maintain higher labeling indices.


Detection of barbiturates by latex agglutination inhibition. A latex-agglutination inhibition test was developed and evaluated for the detection of barbiturates, primarily in urine, but it has applicability to serum. The 2-h test was performed with samples free of gross debris in a 37 degree C heat block and the reaction between the barbiturate antibody and the barbiturate-latex, at pH 7.3, was inhibited by urines containing secobarbital, amobarbital, pentobarbital, butabarbital, or phenobarbital. For laboratory standards the test was particularly sensitive to secobarbital (300 microgram/litre) and relatively insensitive to amobarbital (5000 microgram/litre). In  clinical specimens some barbiturates were detected at levels as low as 150 microgram/litre. The test was specific, and negative endpoints were frequently noted in as little as 30 min. The effects of variables (antiserum dilution, urine specific gravity, heat block temperature, sample size, and type of barbiturate) on the degree of agglutination were also determined.


Alcohol-associated deaths in the District of Columbia--a postmortem study. Ethyl alcohol and its lethal effects were present either in the victim or in the environment, including persons responsible for a given death, in 53% of the cases autopsied during a six-month period at the Office of the Chief Medical Examiner in the District of Columbia. The results of this small, admittedly biased, sample indicate that the acute and chronic effects of alcohol are a major public health problem in this jurisdiction. Comparative figures from other medical examiner's systems suggest the national prevalence of the problem and confirm the gross inadequacy of data from death certificates for such research. Only when the combination of accurate pathological, toxicological, and historical information concerning all types of deaths is available can reliable statistics regarding the numbers and types of deaths related to alcohol be obtained.


Phencyclidine-related deaths in Los Angeles County, 1976. Concentrations of phencyclidine in blood and liver are presented in five fatal cases occurring in Los Angeles County in 1976. Eleven other deaths in which phencyclidine contributed to death are described; acute psychotic reactions were observed in some of these cases. Two cases involved the drowning of individuals whose swimming capabilities may have been diminished from the effects of PCP. One case is presented in which a 20-year-old male took a massive overdose of phencyclidine for suicidal purposes.


Spontaneous pneumothorax in the newborn: a report of two fatalities. Spontaneous pneumothorax is present in 1 to 2% of healthy full-term newborn infants. Virtually all cases have resolution of the pneumothorax without sequelae and in fact without the condition being diagnosed. Two fatal cases are presented. Anyone doing medicolegal autopsies should be aware of this entity so that X-rays or other appropriate methods to demonstrate it can be used.


Postmortem intravascular bubbling: a decompression artifact? The relationships between drowning occurring in divers using compressed air, with subsequent recovery of the body to the surface, and the finding of intravascular gas bubbles at autopsy were studied. Guinea pigs were exposed to compressed air in a hyperbaric chamber at various depths [98, 294, and 392 kPa (1,3, and 4 atm)] for various intervals and then drowned at depth. Various decompression schedules were used in returning the drowned animals to the surface. Autopsy examination indicated that large and small intravascular gas bubbles may be found, in the absence of traumatic air embolism or decompression sickness, as a result of the process of decompression alone. Postmortem findings of intravascular bubbles bin drowned divers must be interpreted with caution and the importance of a full history of the incident, including depth and time of diving and evidence of ascent before drowning, are critical to the proper interpretation of intravascular gas bubbles.


Bilateral linear subconjunctival hemorrhage in a trauma patient. A case of bilateral linear subconjunctival hemorrhage secondary to a gunshot wound to the chest has been presented. The linear character was explained by cardiac tamponade and nearly instantaneous cessation of cardiac output.


Premature deaths in persons with seizure disorders--subtherapeutic levels of anticonvulsant drugs in postmortem blood specimens. Eleven autopsy cases from a Colorado coroner's service are presented in which postmortem levels of anticonvulsant drugs were subtherapeutic. Scene investigation or medical history, or both, revealed evidence of epilepsy in all eleven cases. Five of the deaths (three drowning and two with aspiration of gastric contents) occurred during a suspected seizure. The six remaining deaths were attributed to asphyxia associated with terminal seizures. Because anatomic evidence of epilepsy is often minimal and nonspecific, the authors think that levels of anticonvulsant drugs should be determined in cases of sudden unexpected death with a history of epilepsy. It is probable that these eleven deaths were preventable with better patient motivation and compliance with the physicians' orders. Many epileptic patients fail to take their medications as directed because of the undesired side effects. Lower doses of anticonvulsant drugs could reduce the degree and number of unwanted side effects and encourage patient compliance. Therefore, careful monitoring of serum anticonvulsant levels during the life of the patient might permit lower but still adequate drug levels with fewer adverse effects and hence encourage the epileptic to comply with the doctor's orders, take his medication, and live.


Frequency distribution and discrimination probability of twelve protein genetic variants in human blood as functions of race, sex, and age. Fresh blood samples were obtained from 6004 whites, 1025 blacks, 1596 Chicano/Amerindians, and 3053 Asians of California and Hawaii. The samples were typed for ABO and Rh groups and were analyzed electrophoretically for ten genetically determined protein variant systems. The effects of race, age, and sex on phenotypic frequencies within each of the twelve genetic systems were investigated. Large frequency differences were found between races but not between different age and sex subgroups within races. It was also demonstrated that the twelve genetic systems behaved statistically independently. Discrimination probabilities were computed for each of the four ethnic groups. These serve as a measure of the effectiveness of the twelve genetic systems examined in individualizing blood samples. The method is discussed for computing the probability that a randomly chosen individual of a given ethnic group possesses the same blood phenotypes as found in a predetermined sample of blood. The results presented here should prove useful in the investigation of civil and criminal cases involving blood samples.


Problems of reliability in the phenotyping of erythrocyte acid phosphatase in bloodstains. Erythrocyte acid phosphatase is a useful system for the crime laboratory for both fresh and degraded blood and bloodstains, provided the inherent problems of phenotyping this particular enzyme system are recognized. Because of the great number of variables affecting this enzyme system in vitro, phenotyping should not be attempted unless the complete history of origin and handling of the sample is known.


Weakly basic impurities in illicit amphetamine. In this paper the isolation and identification of two pyrimidines, five pyridines, and one pyridone as impurities in illicit amphetamines prepared by the Leuckart synthesis are reported. Isolation was achieved by repeated thin-layer chromatography with various solvent mixtures, while identification was done by both high and low resolution mass spectrometry and 1H and 13C NMR spectroscopy. Some chromatographic data are reported and a quantitative analysis of a reaction mixture and an illicit amphetamine is given.


Determination of serum myoglobin level after death in the diagnosis of sudden coronary artery occlusion. Serum myoglobin was determined by radioimmunoassay in 20 cases of sudden and unexpected death resulting from acute coronary occlusion. There was consistent elevation of myoglobin 2 h after death, with peaking at 3 h. No comparable elevation of serum myoglobin level was noted in patients who had succumbed to pulmonary embolism, ruptured aortic aneurysm, or subarachnoid or intracerebral hemorrhage. Thus, determination of serum myoglobin seems useful in confirming or establishing acute coronary occlusion as the cause of sudden and unexpected death.


An improved technique using dental histology for estimation of adult age. Multiple regression analysis has allowed considerable improvement of age estimates on adult human teeth. Not only were the estimates more precise, but they also involved fewer variables, decreasing the probability of observer error. There was consistent evidence that the second molar (Position 7) was the best to use for histological aging techniques. The reduction in variables to just secondary dentin and root transparency has also resulted in a technique that can be used with some confidence in populations other than the one sampled. Thus, dental aging can be used in the same way as epiphyseal fusion, osteon aging, cranial sutures, and changes in the public symphysis that have been used with other contemporary and prehistoric populations.


Reliability of the acid phosphatase test for the identification of seminal fluid. Data from 100 cases of alleged rape victims demonstrate why the author believes the AP test to be a reliable tool, when employed by an expert for the identification of seminal fluid.


Physicochemical and biological properties of mycobacteriocin M12 produced by Mycobacterium smegmatis ATCC 25855. A mycobacteriocin (M12) produced by Mycobacterium smegmatic ATCC 25855 was partially purified by ammonium sulphate precipitation followed by DEAE-cellulose chromatography and Sephadex G100 chromatography. Production of M12 was maximal when bacteria were harvested after 3 d cultivation in liquid medium and disrupted by sonication. The molecular weight of M12, estimated by Sephadex G100 chromatograpy, was about 85000. M12 was sensitive to proteolytic enzymes but resistant to DNAase and RNAase, and was relatively stable to heat treatment, sonication, ultraviolet irradiation and pH over the range 4 to 8. When sensitive bacteria were exposed to the mycobacteriocin, the number of viable cells began to decrease after about 6 h incubation. The killing curve of M12 thus appeared to be a multiple-hit curve. Electron microscopic observation revealed that the mycobacteriocin induced morphological changes in the cells; these were partial loss of ribosomes, enlargement of lipoidal inclusion bodies and thickening of the cell envelope. The activity spectrum of M12 was restricted to the genus Mycobacterium.


Linkage analysis in Dictyostelium discoideum using multiply marked tester strains: establishment of linkage group VII and the reassessment of earlier linkage data. To aid linkage analysis and mapping studies in Dictyostelium discoideum, we have constructed several tester strains with easily scored mutations characterizing the six currently identified linkage groups. Use has been made of conditionally lethal mutants unable to grow upon Bacillus subtilis, and the locus of the mutation involved (bsgA) has been assigned to linkage group III. The mutation cobA1, which confers resistance to cobaltous chloride, has been assigned to a previously unidentified linkage group (VII). The temperature-sensitive growth mutation tsgC7, previously reported to define linkage group V, has been reassigned to group III, leaving linkage group V presently unmarked. The further use of genetic tester strains is described.


A co-operative numerical analysis of Mycobacterium gastri, Mycobacterium kansasii and Mycobacterium marinum. A co-operative taxonomic study has been performed on slowly growing photochromogenic mycobacteria (Runyon Group I) and closely related organisms. Phenetic data on 54 strains, studied in seven laboratories, were collected and analysed by numerical taxonomic methods. Immunological properties and phage susceptibility patterns were analysed independently to establish correlation with numerical classification. Mycobacterium gastri, M. kansasii and M. marinum appeared as distinct well-defined clusters and the serological and phage data supported the resolution of these three species. A table of definitive properties is presented. Two strains each of M. simiae and M. asiaticum formed a loose cluster which was clearly separated from the previously mentioned three species; the small number of strains examined precluded the establishment of a list of definitive properties of these two species. It is concluded that the Runyon Groups, which provided a practical though arbitrary basis for establishment of a series of co-operative studies, have served their purpose and should now be supplanted by classification and nomenclature based on species.


The labelling of galactose residues in hepatitis B surface antigen glycoprotein. The 20 to 25 nm particles of hepatitis B surface antigen were purified from the serum of a carrier chimpanzee. Five major polypeptide species were revealed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Treatment of the particles with neuraminidase (EC 3.2.1.18) and galactose oxidase (EC 1.1.3.9) followed by reduction with tritiated sodium borohydride labelled galactose residues in a single glycoprotein with an apparent mol. wt. of 28 000. The glycoprotein was not labelled when neuraminidase treatment was omitted, indicating that the galactose residues are in subterminal positions in the oligosaccharide chains. There was no significant incorporation of radiolabel into lipid. The serological activity of the antigen, as measured by a competitive double-antibody radioimmunoprecipitation assay, was not altered by the labelling procedure nor by exposure to neuraminidase alone.


Interferon induction and action in human lymphoblastoid cells infected with measles virus. Virus replication, cytopathic effect and interferon production were measured in Namalva lymphoblastoid cells infected with measles viruses. Eight virus strains of different origin or passage history were compared. An inverse relationship seemed to exist between the abilities of strains to induce interferon and to replicate to high titres. Two representative strains were found to be highly sensitive to lymphoblastoid cell interferon, when tested in a line of monkey kidney cells (Vero). In contrast, Namalva cells were found to be highly insensitive to autologous interferon when challenged with measles or Semliki Forest virus (SFV).


Mapping of adenovirus type 5 temperature-sensitive mutations by marker rescue in enhanced double DNA infections. Adenovirus type 5 DNA has low infectivity (Graham & van der Eb, 1973) which can be increased by various techniques, one of which is the dimethyl sulphoxide (DMSO) boost (Stow & Wilkie, 1976). In this report, it is shown that DMSO treatment of adenovirus 5 DNA-infected HeLa cells results in a 10-fold increase in plaque formation, and that this can be used to facilitate marker rescue experiments. Double DNA infections were performed by the calcium phosphate method, co-precipitating intact temperature-sensitive mutant DNA with purified wild-type DNA restriction endonuclease fragments. Analysis of the plaquing ability of these mixtures and any progeny virus has resulted in the assignment of six temperature-sensitive mutations to discrete physical locations on the adenovirus type 5 genome. These locations are discussed with respect to the mutant phenotypes and the transcription-translation products of the appropriate regions.


The pathogenesis of avirulent Semliki Forest virus infections in athymic nude mice. The course and outcome of intraperitoneally induced infections with the avirulent strain A7(74) of Semliki Forest virus have been studied in athymic 'nude' (nu/nu) mice, their heterozygous (nu/ + ) littermates and conventional Swiss A2G mice. The main distinguishing characteristics of the infection in the nu/nu mice were the persistence of virus in the brain after an initial phase of incomplete virus clearance and the apparent establishment of a secondary phase of virus replication in the brain which was associated with a falling neutralizing antibody response. This secondary phase of virus replication persisted until at least the 28th day after inoculation. In addition the typical histological lesions of encephalitis induced by this virus were rare and focal demyelination, which occurred at a light microscopy level in up to 26% of nu/ + and Swiss A2G mice, was not observed. It is suggested that in immunocompetent mice the development of lesions including demyelination may be a result of an immunopathological response to virus infection which is related to the presence of thymus derived lymphocytes.


Absence of "cheese effect" during deprenyl therapy: some recent studies. Although the selective monoamine oxidase (MAO) B inhibitor, (-)deprenyl, has been shown to be free from the "cheese effect" in man after tyramine challenge, the reason for this is far from clear: it may well be independent of the selective inhibitory action of the drug, for during chronic administration there is some evidence to suggest that both A and B forms of the enzyme are equally inhibited. By-passing the putative MAO A gut barrier in the pig (chosen because it possesses MAO B alone in all other tissues) by intravenous tyramine administration into the deprenyl-pretreated animal failed to provoke a pressor response, despite substantial MAO inhibition. Conversely, clorgyline (MAO A inhibitor) pretreatment, which resulted in minimal MAO inhibition, produced a profound hypertensive response, resembling that observed with the non-MAO-inhibiting drug, isoniazid. The most parsimonious explanation for these findings may be that two separate but closely associated pharmacological effects are normally found with "orthodox" MAO inhibitors, enzyme inhibition proper and facilitation of noradrenaline release from its binding sites during tyramine challenge.


Overview of present day treatment of Parkinson's disease. In the light of present day knowledge, augmenting striatal dopaminergic activity is the most effective means for controlling the symptoms of parkinsonism. This is best accomplished by the administration of levodopa with a peripheral decarboxylase inhibitor. However, limitations in its benefits develop after long-term administration in a substantial number of patients. In an attempt to overcome these a number of pharmacological agents acting on striatal dopaminergic mechanisms have undergone clinical trial. Of those tried Deprenyl, an MAO-B inhibitor, given with levodopa and carbidopa has shown the most promise. Preliminary results in 35 patients indicate that it is useful in diminishing the incidence of "on-off" phenomena--one of the most limiting reactions to levodopa--as well as enabling some patients to recoup their loss of therapeutic benefits. Though far from resolving all of the therapeutic difficulties encountered with prolonged use of levodopa, it appears to be a valuable adjunctive agent for the long-term problem patient.


Amphetamine and 2-phenylethylamine in post-mortem Parkinsonian brain after (-)deprenyl administration. Deprenyl is an inhibitor of monoamine oxidase type B, the enzyme responsible for 2-phenylethylamine oxidation, and is used in conjunction with L-Dopa therapy in Parkinson's disease. Post-mortem studies in human brain tissue have shown that after (-)deprenyl administration to parkinsonian patients amphetamine is present in concentrations up to 56 ng/g. It also could be shown that phenylethylamine concentrations are substantially increased in such patients. Phenylethylamine and amphetamine have been investigated using a gas chromatographic technique.


An electron-microscopic study of basal cell carcinoma. Thirty-two basal cell carcinomas have been examined by electron microscopy. The majority exhibit cellular polymorphism and the most frequently encountered non-epithelial unit is the Langerhans cell. The nature of basal cell carcinoma and the function of the Langerhans cell are discussed in relation to this observation.


Cellular junctions in human oesophageal epithelium. The appearances of this intercellular junctions in normal and in inflamed oesophageal epithelium are described. Typical hemidesmosomes occur along the abluminat aspect of the basal cells. Desmosomes are most frequent in the prickle cell layer, where desmosome fields may occur, and in the lower functional cell layer. Their fate in the upper layers is not known. Gap junctions are few in the basal cell layer and rare in the most superficial layers. They are maximal in the prickle cell layer. Tight junctions only occur in inflamed tissue between the most superficial cells usually as part of a lateral intercellular junctional complex that also contains belt desmosomes. They may represent attempts by a non-keratinised epithelium to increase its defences against toxic luminal contents.


A complete form of testicular feminisation syndrome; a light and electron microscopy study. A case is described of testicular feminisation syndrome in a 19-yr-old patient with a normal female appearance. A laparotomy with removal of the gonads was performed. The latter looked like testes with intraparenchymal nodules. Light and electron microscopy study of these nodules revealed the presence of immature seminiferous-like tubules and of Leydig cell clusters. The tubules were filled with clear Sertoli cells, few degenerative dark cells and scanty spermatogonia. Thin collagen bundles surrounded the tubules and the foci of Leydig cells without any crystals of Reinke. The immaturity of all these cellular components could be connected with a mutation at a repressive locus which could be responsible for the abnormalities observed in the different steps of androgen action at target cell level.


Ultrastructure of the placenta in prolonged pregnancy. An electron-microscopic study has shown that in placentae from prolonged pregnancies there is hyperplasia of the villous cytotrophoblastic cells, degeneration of occasional isolated cytotrophoblastic cells, a paucity of syncytial microvilli in some areas and microvillous proliferation in others, abnormalities of microvillous form, focal syncytial necrosis, dilatation of syncytial endoplasmic reticulum, decreased synctial pinocytic activity, a reduced size and number of syncytial mitochondira, thickening of the trophoblastic basement membrane and contraction, blebbing and vacuolation of endothelial cells of the stromal foetal villous capillaries. Many of these morphological changes indicate that there is, in prolonged pregnancy, a decline in trophoblastic functional activity but it is suggested that this is due, not to placental senescence, but to a relatively mild, sustained uteroplacental ischaemia. Although there is morphological evidence to suggest that compensatory mechanisms come into play to limit the effects on the placenta of uteroplacental ischaemia the changes in the foetal capillaries, which are of unknown pathogenesis, will result in decreased foetal perfusion of the placenta and thus restrict still further adequate materno-foetal transfer.


Morphological aspects of glucocorticoid-induced cell death in human lymphoblastoid cells. Morphological aspects of cell death associated with a cytolethal concentration of methylprednisolone sodium succinate (500 micrograms/ml) on the BLA1 lymphoblastoid cell line were studied over a 48-hr incubation period by light, transmission and scanning electron microscopy. Studies revealed two distinctive morphological changes induced by the steroid from 1 hr onwards after treatment. One showed contortion and "blebbing" of the cytoplasm and nucleus accompanied or followed by nuclear pyknosis, resulting in the formation of membrane-bounded bodies containing apparently normal cytoplasmic organelles with or without nuclear fragments. The other showed "rounding up" of the cell with loss of cytoplasmic protrusions and long slender surface processes, aggregation of well-preserved cytoplasmic organelles, accompanied by nuclear pyknosis and fragmentation. In both cases many of the features are typical of apoptosis. The subsequent degeneration of cells and fragments not unexpectedly resembled in vitro autolysis. This in-vitro system is suitable for studying the early biochemical events and intracellular control mechanisms of apoptosis.


Long-term effects of control and predictability-enhancing interventions: findings and ethical issues. The long-term effects of participating in a field experiment on the effects of control and predictability-enhancing interventions are reported. Retirement home residents who had initially benefited from being exposed to a specific positive predictable or controllable event were assessed at three different intervals after the study was terminated. Health and psychological status data collected 24, 30, and 42 months after the study was terminated indicated no positive long-term effects attributable to the interventions. In fact, groups that had initially benefited from the interventions exhibited precipitous declines once the study was terminated, whereas groups that had not benefited remained stable over time. The theoretical and ethical implications of these data are discussed.


Reported physical symptoms elicited by unpredictable events and the type A coronary-prone behavior pattern. Unpredictable and uncontrollable events are associated with a variety of illnesses. It was hypothesized that unpredictable aversive events are causally linked to physical symptom reporting and that the Type A coronary-prone behavior pattern affects symptom reporting, such that Type A individuals fail to report symptoms when they expect to continue working on a task as compared to when they believe they have completed it. In the present research, Type A and Type B women reported symptoms either at the end or in the middle of listening to unpredictable, predictable or ambient noise in the laboratory. Results showed that unpredictable noise produced more symptom reporting than predictable noise, which in turn produced more symptom reporting than the ambient noise; Type A individuals reported fewer symptoms in the middle of the task than at the end, whereas Type B's did not show this differential effect. Thus, both hypotheses were confirmed. Several possible explanations of the results are offered, and implications of the findings are discussed.


Self-focusing effects of heartbeat feedback. Two studies tested the hypothesis that auditory heartbeat feedback leads to an increase in self-directed attention. In Experiment 1, subjects exposed to a sound representing their heartbeat made greater self-attributions for hypothetical outcomes than did subjects exposed to the same sound identified as an extraneous noise. Furthermore, subjects in the heartbeat condition showed a pattern of color-naming latencies (on a color-word test) that was consistent with the hypothesis that self-related information was being activated in memory. In contrast, no such pattern was observed among subjects in the noise condition. In Experiment 2, comparisons with appropriate control groups indicated that neither an extraneous noise nor the attachment of a heartbeat-recording device influenced self-attribution, but that the presence of either a constant or an accelerating heartbeat increased self-attribution. The latter two conditions did not differ from each other. Discussion centers on the findings' methodological and theoretical implications.


Facial expressions as conditioned stimuli for electrodermal responses: a case of "preparedness"? Converging data suggest that human facial behavior has an evolutionary basis. Combining these data with Seligman's preparedness theory, it was predicted that facial expressions of anger should be more readily associated with aversive events than should expressions of happiness. Two experiments involving differential electrodermal conditioning to pictures of faces, with electric shock as the unconditioned stimulus, were performed. In the first experiment, the subjects were exposed to two pictures of the same person, one with an angry and one with a happy expression. For half of the subjects, the shock followed the angry face, and for the other half, it followed the happy face. In the second experiment, three groups of subjects differentiated between pictures of male and female faces, both showing angry, neutral, and happy expressions. Responses to angry conditioned stimuli showed significant resistance to extinction in both experiments, with a larger effect in Experiment 2. Responses to happy or neutral conditioned stimuli, on the other hand, extinguished immediately when the shock was withheld. The results are related to conditioning to phobic stimuli and to the preparedness theory.


Facilitating effects of erotica on aggression against women. In order to examine the effects of highly erotic stimuli on aggression against females, male subjects were angered by a male or female confederate and exposed to an erotic film, an aggressive film, or a nonfilm condition. Subjects were given two opportunities to aggress against the confederate. It was found that both the aggressive and the erotic films increased aggression against both targets during the first and second aggression opportunities. However, the erotic film facilitated aggression against the female target across the two aggression sessions. The processes operating to cause this increase are discussed in terms of reducing restraints against aggressive behavior and the specific cue value of erotic films.


Action potentials in gland cells of rat pituitary pars intermedia: inhibition by dopamine, an inhibitor of MSH secretion. 1. Cells were dissociated from rat pituitary pars intermedia, maintained in culture, and subjected to electrophysiological study.2. Recorded membrane potentials varied widely (range - 18 to about - 80 mV). They were relatively insensitive to changes in external Na but were rapidly and reversibly lowered by excess K.3. Action potentials were elicited by passing current through intracellular recording electrodes. They were reversibly blocked by tetrodotoxin (TTX, 2 x 10(-6)M) or by removal of Na from the recording solution and thus appeared to be Na spikes. Cells yielding action potentials in response to depolarization had relatively high membrane potentials (about - 65 mV) which may be representative of the true resting membrane potential of pars intermedia cells.4. Spontaneous action potentials were recorded extracellularly from nearly all the many isolated pars intermedia cells studied with a microsuction electrode. Their amplitude was reduced by TTX (0.1-2 x 10(-6)M). Electron microscopic examination of cells producing action potentials showed them to be hormone-containing parenchymal (gland) cells.5. Dopamine (10(-6)M), a presumed physiological inhibitor of secretion of melanocyte stimulating hormone (MSH) from pars intermedia cells, decreased the frequency of spontaneous action potentials but not their amplitude. Similar effects were seen with noradrenaline (10(-6)M), another inhibitor of MSH secretion, whereas isoprenaline and 5-hydroxytryptamine (5-HT), which do not inhibit MSH secretion, had no effect.6. Action potentials may be involved in stimulus-secretion coupling in pars intermedia cells.


Ballistic contractions in fast or slow human muscles: discharge patterns of single motor units. 1. Single motor units were recorded from the masseter, soleus and first dorsal interosseous muscles of normal adult man. An analysis of discharge patterns was carried out either during slow ramp voluntary contractions, or during self-initiated isolated ballistic voluntary contractions. The isometric myogram was simultaneously recorded.2. Each motor unit was only recruited when the peak force of a brisk contraction exceeded a certain value and a ;ballistic force threshold' (in kg) was estimated for the unit from a large series of brisk contractions of different strengths. For each muscle, the ranking order for recruitment of different motor units recorded from one electrode position was virtually identical in slow ramp versus brisk ballistic contractions of different force (Kendall rank correlation coefficient = 0.91-1.0). There was no evidence for any consistent selective activation of fast twitch motor units in ballistic contractions.3. The ballistic force threshold is considerably reduced with respect to the slow ramp force threshold for the motor units of the soleus muscle. This drop is also marked for the units of the first interosseous and tibialis anterior muscles, whereas it is only small for the units of the masseter muscle. These data have been validated after consideration of the complicating factor related to the possible differential involvement of synergic muscles in ramp or ballistic contractions.4. In the masseter and first interosseous muscles, the time to peak is about 80 msec in small ballistic voluntary contractions and it increases to about 150 msec in strong contractions. This effect appears related to repetitive discharges of single motor units when their force threshold is exceeded. By contrast, in the soleus muscle, the time to peak remains at about 150 msec both in small and in strong ballistic contractions and most soleus motor units fire only one spike in the ballistic burst.5. Brisk ballistic contractions are graded in force by the recruitment of additional motor units according to their usual rank order. The importance of rate gradation through the repetitive firing of motor units varies in the different human muscles investigated, being quite significant in isometric brisk contractions of the masseter and first interosseous muscles but much less so in the soleus muscle in which little repetitive firing of single motor units was observed over the range of ballistic forces studied.


Saccadic, smooth pursuit, and optokinetic eye movements of the trained cat. 1. Cats were trained to track a small target by rewarding them for keeping their eyes on target. Eye movements were measured by the electromagnetic search coil technique. 2. Cat saccades are qualitatively similar to primate saccades, but exhibit more variability in their parameters. However, they have longer durations and lower maximum velocities than primate saccades. As in the monkey, the duration of the horizontal or vertical component of an oblique saccade is lengthened when the orthogonal component has a larger amplitude. Cat saccades can be modified in midflight like human saccades. Opening the visual feed-back loop by controlling target position with eye position causes the cat to execute a staircase of equal amplitude saccades if a retinal error is present. Increasing the amount of visual feed-back induces saccadic oscillations. 3. Horizontal smooth pursuit of a 0 . 5 deg visual target is limited to velocities of less than 1 deg/sec. However, moving an optokinetic background with the 0 . 5 deg target enables the cat to achieve higher horizontal smooth eye velocities of up to 8 . 5 deg/sec. Prolonged (10-20 sec) constant velocity rotation of an optokinetic drum evokes horizontal slow-phase velocities of up to 28 deg/sec. In response to vertical movements of the target and optokinetic background, smooth eye movements reached 6 deg/sec maximum upward velocities but only 2 . 5 deg/sec maximum downward velocities. Opening the feed back loop with no retinal error present causes the eye to exhibit a growing smooth trajectory. The response to a Rashbass step-ramp target suggests that the feline smooth response is a function of target movement rather than displacement. 4. These data suggest that cat saccadic eye movements resemble those of primates while the cat smooth pursuit and optokinetically induced eye movements are more similar to those of the rabbit.


The effect of contrast on the transfer properties of cat retinal ganglion cells. 1. Variation in stimulus contrast produces a marked effect on the dynamics of the cat retina. This contrast effect was investigated by measurement of the responses of X and Y ganglion cells. The stimuli were sine gratings or rectangular spots modulated by a temporal signal which was a sum of sinusoids. Fourier analysis of the neural response to such a stimulus allowed us to calculate first order and second order frequency kernels. 2. The first order frequency kernel of both X and Y ganglion cells became more sharply tuned at higher contrasts. The peak amplitude also shifted to higher temporal frequency at higher contrasts. Responses to low frequencies of modulation (less than 1 Hz) grew less than proportionally with contrast. However, response amplitudes at higher modulation frequencies (greater than 4 Hz) scaled approximately proportionally with contrast. Also, there was a marked phase advance in these latter components as contrast increased. 3. The contrast effect was significantly larger for Y cells than for X cells. 4. The first order frequency kernel was measured with single sine waves as well as with the sum of sinusoids as a modulation signal. The transfer function measured in this way was much less affected by increases in contrast. This implied that stimulus energy at one temporal frequency could affect the response amplitude and phase shift at another temporal frequency. 5. Direct proof was found that modulation at one frequency modifies the response at other frequencies. This was demonstrated by perturbation experiments in which the modulation stimulus was the sum of one strong perturbing sinusoid and seven weak test sinusoids. 6. The shape of the graph of the amplitude of the first order frequency kernel vs. temporal frequency did not depend on the amplitudes of the first order components, but rather on local retinal contrast. This was shown in an experiment with a sine grating placed at different positions in the visual field. The shape of the first order kernel did not vary with spatial phase, while the magnitudes of the first order responses varied greatly with spatial phase. 7. Models for the contrast gain control mechanism are considered in the Discussion.


Properties of synaptic linkage from long ranging afferents onto dorsal horn neurones in normal and deafferented cats. 1. In intact cats, dorsal horn cells sometimes respond to afferents entering the cord three or four segments more rostral. If dorsal roots near a segment have been cut for at least 4 weeks, many more cells respond to these long ranging afferents. Using extra- and intracellular recording, we examined the change in the nature of the connectivity of the long ranging afferents from dorsal roots L3 and L4 onto cells in L7. 2. In intact animals 33% of all cells in L7 recorded extracellularly and 48% of those recorded intracellularly exhibited responses to electrical stimulation of skin whose afferents entered the spinal cord over dorsal roots L3 and L4. Most of these responses had a long latency and followed high frequency stimulation poorly. 3. Thirty-eight to fifty-one days after cutting dorsal roots L5-S2, 76% of cells recorded intracellularly in L7 responded to long ranging afferents, in contrast to 48% in the intact cord. In these preparations 48% of all cells responded in less than 5 msec versus 12% in intact cats. Furthermore, 21% of the cells had natural receptive fields in the distant dermatome versus 1% in intact animals. 4. Chronic deafferentation of a segment increased the number of cells responding to afferents arriving over distal dorsal roots and increased the speed and power of the responses.


Increased formation of diamines and polyamines in the pregnant rat. 1. The urinary excretion of histamine, methylhistamine, putrescine, cadaverine, spermidine and spermine was examined before, during and after pregnancy in rats. 2. During the last third of undisturbed pregnancy a distinct and steep rise occurred in the excretion of all amines studied except spermine. The peak values were found a few days before the birth of the young. In spermidine excretion a second peak was observed one or two days after delivery. 3. Before and during the first 2 weeks of gestation on a molar basis putrescine excretion was the greatest one. During the last trimester histamine was excreted in the largest amount. 4. Under the influence of the diamine oxidase inhibitor aminoguanidine the general pattern of excretion of diamines and polyamines in pregnant rats remained essentially unchanged but the total amount excreted increased. Most conspicuous was the great elevation of urinary contents of putrescine and cadaverine.


Acid secretion by isolated canine gastric mucosa. 1. An isolated gastric mucosal preparation from the dog stomach which is capable of acid secretion is described. Average values for normal resting potential difference (p.d.) was 49 +/- 2 mV (mucosal side negative with respect to the serosal side), short-circuit current (Isc) was 172 +/- 4 muA and resistance (R) was 285 +/- 6 omega.cm2. Low rates of spontaneous acid secretion (0-0.58 muequiv/cm2.hr) were present initially but following short-circuiting of the tissue these values decreased to low levels (less than 0.1 muequiv/cm2.hr) within an hour. 2. Histamine in doses exceeding 10(-6)M stimulated acid secretion, increased Isc and decreased R. Concentrations ranging from 10(-5) to 8 X 10(-4)M produced maximal secretion. The maximal secretory rate achieved was 4.24 +/- 0.35 muequiv/cm2.hr. 3. Pentagastrin (10(-8)M) and acetylcholine (10(-6)--10(-5)M) also stimulated acid secretion with a lower maximal secretion as compared to histamine stimulation. These concentrations of pentagastrin and acetylcholine did not alter histamine stimulated acid secretion. Higher concentrations of pentagastrin (10(-6)M) and acetylcholine (10(-4) M) reversibly inhibited acid secretion of histamine stimulated mucosa. 4. These results demonstrate that there are many similarities between in vitro and in vivo findings on the dog stomach, indicating the great potential of the in vitro dog gastric mucosa for studies on the mechanism of action and interaction of gastric secretagogues.


Influence of atrial stretch receptors on hypothalamic neurosecretory neurones. 1. The effects of stimulation of atrial receptors on hypothalamic neurosecretory cells were investigated in anaesthetized dogs and cats. Atrial receptors were activated by stretching the left and the right atria while action potentials of individual neurosecretory neurones in the supraoptic (s.o.n.) and paraventricular (p.v.m.) nuclei of the hypothalamus were recorded. 2. Stretching the left atrium markedly decreased firing frequencies of 'antidromically identified' s.o.n. and p.v.n. neurones in dogs and cats; 98% of neurones in dogs and 70% in cats were thus inhibited. Heart rate accelerated following a transient reflexly induced deceleration. The blood pressure was not affected. The magnitude and duration of inhibitory effects produced by atrial stretch on s.o.n. and p.v.n. neurones paralleled changes observed in heart rate. Approximately one third of 'unidentified' cells in s.o.n. and p.v.n. (those which could not be activated antidromically) were inhibited by left atrium stretch. 3. Bilateral vagotomy abolished the effects on neurosecretory neurones as well as on heart rate produced by left atrial stretch, indicating that the vagus nerves carry afferent impulses responsible for the observed changes. 4. Stretching the right atrium did not produce changes in firing frequencies of s.o.n. and p.v.n. neurones in dogs and cats, although cardiac rate was increased considerably by such stretch. Stimulation of the left and right atria was tested in the same animal in succession to permit comparison of the diverse results. 5. Interaction of responses originating from atrial receptors, baro- and chemoreceptors were studied. During carotid occlusion or stimulation of chemoreceptors activity of the neurosecretory cells was greatly augmented. Left atrial stretch when then applied evoked slight or no reduction in activity in s.o.n. and p.v.n. neurones. These results were interpreted to mean that the influence of baro- or chemoreceptors on neurosecretory neurones probably is stronger than that originating from atrial receptors. 6. Unlike the observations made in rats, no rhythmically bursting neurones (phasic cells) were found in dogs and cats. However, atrial stretch sometimes evoked a rhythmic bursting pattern which appeared only during stretch. 7. It is concluded that activation of left atrial receptors, through afferent impulses carried mainly by vagus nerves, inhibits neurosecretory neurones in s.o.n. and p.v.n. The implications of this finding in relation to the role of ADH in the maintenance of blood volume control were discussed.


Studies on neural mechanisms of the gustatory-salivary reflex in rabbits. 1. Submandibular salivary secretion and the electrical activity of the parasympathetic preganglionic fibres innervating the submandibular gland were recorded in decerebrated rabbits in response to taste stimulation of the tongue. The electrical activity of a taste nerve (chorda tympani) responding to varying taste stimuli was also recorded in the deeply anaesthetized rabbits. These data representing input and output information were compared with each other. 2. Sucrose, quinine, tartaric acid, NH4Cl and KCl which induced a long-lasting response in the taste nerve evoked a continuous salivary secretion, and those chemicals such as NaCl, CaCl2 and MgCl2 which induced a transient activity of the nerve evoked a transient salivary secretion. 3. The magnitude of responses of the whole taste nerve to moderate concentrations of chemical stimuli applied to the anterior part of the tongue was statistically significantly correlated with the volume of reflex submandibular salivation. 4. Parasympathetic preganglionic fibres to the salivary gland were classified into two types according to their responsiveness to taste stimuli; taste-sensitive and taste-insensitive fibres. The magnitude of electrical activity of the taste nerve fibres was significantly correlated with that of the taste-sensitive preganglionic fibres to stimulation of the tongue with varying taste stimuli. 5. By calculating correlations between responses of the taste fibres to each of the four basic taste stimuli and all the stimuli tested, it was concluded that afferent inputs from the taste of sucrose and NaCl were different, while those of HCl and quinine were similar. On the other hand, it was found by the same procedure for the preganglionic fibres that sucrose and NaCl, and HCl and quinine produced a similar response profile, respectively. This result means that the afferent taste inputs are processed into appropriate outputs (perhaps on a hedonic basis) in the lower brain stem without involvement of higher central nervous mechanisms.


A study of the factors responsible for rate-dependent shortening of the action potential in mammalian ventricular muscle. 1. An intracellular micro-electrode was used to record action potentials from superficial cells of a cat papillary muscle during isometric contractions. The muscle was stimulated regularly and test stimuli were interpolated at various times between regular (control) responses. 2. The duration of test action potentials (measured at 80% repolarization) increases exponentially with time as the interval between the test stimulus and the preceeding stimulus is increased and a curve drawn through the data reaches a plateau at test intervals of 1.0-1.5 s. This curve is considered to reflect the time course with which membrane conductances return to their pre-stimulus values after a control response, and it is known as the 'electrical restitution curve'. 3. At much longer test intervals the action potential duration duration increases again and it approaches the rested state value of about 0.5 s when the interval between stimuli is 200-300 s. 4. Interventions that raise the peak tension developed in isometric contractions, such as an increase in the rate of stimulation or in the bathing calcium concentration, displace the electrical restitution curve downwards (to shorter action potential durations) and to the left (to shorter stimulus intervals). This shift in the curve is accompanied by a reduction in its magnitude (i.e. the difference in duration between the earliest possible action potential and the plateau value), but the interventions differ in their effects on the time course of electrical restitution: an increase in stimulus frequency causes a marked slowing, whereas an increase in bathing calcium concentration produces a slight speeding up of its time course. 5. The reduction in action potential duration produced by an increase in stimulus frequency (rate-dependent shortening) can be separated into two components, one resulting from the downward displacement of the electrical restitution curve and the other depending on the time available between consecutive responses for membrane recovery. The second component becomes increasingly important at stimulus frequencies above 100 min-1. 6. Changes in action potential duration observed during the tension staircases produced by regular stimulation of a rested preparation and by paired pulse stimulation can also be accounted for by interaction of downward displacement of the electrical restitution curve and variations in the degree of recovery of the membrane between consecutive responses. 7. Downward displacement of the electrical restitution curve is thought to result from intracellular accumulation of calcium and/or extracellular accumulation of potassium, and the available evidence is considered to favour the former mechanism.


The cardiovascular effects of circulating catecholamines in fetal sheep. 1. Adrenaline and noradrenaline have been infused into the fetal sheep to produce plasma concentrations comparable to those seen during hypoxia and the cardiovascular changes compared with those seen in response to hypoxia. The effect of isoprenaline, methoxamine, and beta- and alpha-adrenergic antagonists were also investigated. 2. There were no significant changes in the blood gas values during any of the infusions except for a mean fall in pH of 0.04 during adrenaline infusion. 3. Adrenaline caused a fall in the fetal heart rate followed by a rise above the control value after 15-20 min. The fall in heart rate was abolished when the rise in blood pressure was blocked with phentolamine. The rise in heart rate was blocked by propranolol. The exact cause of the biphasic changes in heart rate during adrenaline infusion is not clear. 4. A fall in heart rate was not seen with noradrenaline; a small rise was. Propranolol changed this into a fall in heart rate while phentolamine increased the size of the heart rate rise. 5. Phentolamine alone increased the fetal heart rate by 25% and reduced blood pressure by 12%; propranolol alone reduced heart rate by 14% and had no effect on blood pressure. Isoprenaline increased fetal heart rate and reduced blood pressure. 6. The incidence of fetal breathing movements was highly variable. Despite this a significant increase was observed during adrenaline infusion. None of the other infusions had consistent effects. 7. The role of the circulating catecholamines in mediating or modifying the cardiovascular responses to hypoxia in the fetal sheep is discussed.


Electrical property and chemical sensitivity of vascular smooth muscles in normotensive and spontaneously hypersensitive rats. 1. The membrane properties and sensitivity to chemical substances of smooth muscle cells of the portal vein and pulmonary artery were studied in normotensive rats (Wistar Kyoto) and spontaneously hypertensive rats (Okamoto & Aoki) by the micro-electrode method. 2. The parameters of the membrane, i.e. resting membrane potential, the maximum rate of rise of the spike, space constant of the tissue and time constant of the membrane measured from the portal vein were the same in normotensive rats (less than 120 mmHg) and spontaneously hypertensive rats (greater than 165 mmHg). Similar results were also obtained from the pulmonary artery. Such findings indicate that the passive electrical properties of the vascular muscle membrane are not involved in the generation mechanism of hypertension. 3. In the portal vein the maximum slope of the membrane depolarization produced by tenfold increase in external K+ concentration expressed on a logarithmic scale was the same in normal and hypertensive rats (42 and 41 mV, respectively). These observations were confirmed by the effects of application of excess K+ on the pulmonary artery (48 mV in normal and 46 mV in hypertension). With a low concentration of K+, the membrane was depolarized to a greater extent in the portal veins than in the pulmonary arteries of both types of rats. Although the response to K+ differed in vascular muscles excised from the different regions, no functional difference was apparent between normotensive and hypertensive. 4. In both portal vein and pulmonary artery, the smooth muscle membrane of spontaneously hypertensive rats proved to be more sensitive to noradrenaline, i.e. depolarization of the membrane appeared with noradrenaline 10(-9) g/ml. in hypertensive but with 10(-8)g/ml. in normotensive rats. Depolarization block of the spike generation appeared at a slower concentration of noradrenaline in hypertensive rats. Sensitivity of the smooth muscle membrane to prostaglandin E2 in the portal vein was also higher in hypertensive rats. 5. The present results indicate that the only difference between normal and spontaneously hypertensive rats regarding smooth muscle cell membrane of the pulmonary artery and portal vein is increased chemical sensitivity in hypertensive rats, and the passive electrical properties of the membrane probably does not contribute to the generation of hypertension.


Crossed disynaptic inhibition of sacral motoneurones. 1. Intracellular recording was made from motoneurones in lower sacral (S2 and S3) segments of the spinal cord in cats, to analyse the neuronal organization of the inhibition evoked in these motoneurones from contralateral afferents. 2. It was confirmed that stimulation of the lowest threshold afferents of contralateral dorsal roots evokes i.p.s.p.s with latencies similar to those of disynaptic i.p.s.p.s. evoked from group Ia muscle spindle afferents in limb motoneurones. 3. The crossed disynaptic i.p.s.p.s in sacral motoneurones were found to be mediated by interneurones which are themselves inhibited by Renshaw cells, these interneurones and Renshaw cells being activated from the dorsal and ventral roots respectively, on the side of the body opposite to the location of the inhibited motoneurones. 4. In unanaesthetized decerebrate preparations crossed recurrent facilitation of sacral motoneurones was evoked with a time course similar to that of recurrent facilitation of lumbar motoneurones. It was taken to indicate a tonic inhibition of sacral motoneurones by interneurones responsible for their crossed disynaptic inhibition, and a disinhibition following stimulation of contralateral ventral roots. 5. In anaesthetized preparations crossed recurrent inhibition appeared, instead of the recurrent facilitation, in more than one half of the tested motoneurones. 6. A comparison of the input from ipsilateral and contralateral afferents to identified motoneurones of tail muscles with the input to pudendal motoneurones led to the conclusion that crossed disynaptic inhibition is evoked specifically in tail motoneurones. 7. Intracellular staining of sacral motoneurones with horseradish peroxidase revealed that the tail motoneurones and others with crossed disynaptic inhibition differ from the pudendal motoneurones in their location and in a number of morphological features; tail motoneurones are larger, they have differently directed dendrites and they show more extensively branched initial axon collaterals which appeared to ramify only within the ventral and lateral parts of the ipsilateral ventral horn. 8. One Renshaw cell which was stained with horseradish peroxidase was found to project contralaterally, after giving a number of axon collaterals ipsilaterally.


The effect of distension of the pulmonary vein-atrial junction on activity of left atrial receptors. 1. In anaesthetized dogs, the activity from left atrial receptors with vagal afferent fibres has been examined during distension of small balloons in the pulmonary veins or the application of pulsatile pressures to an isolated perfused pouch of the left atrium.2. Eleven fibres were found in nineteen dogs. The receptors discharging into these fibres were located, post mortem, to the atrial endocardium and reasons are given for believing that these fibres were myelinated and the receptors were B or Intermediate.3. Distension of small balloons induced significant increases in the discharge of action potentials from the receptors, the increases were similar to those after infusions of saline or dextran.4. In the perfused pouch the ;dynamic' thresholds for pulsatile pressure were high as were the mean and pulsatile pressures required to induce bursts of action potentials similar to those observed from atrial receptors in the atrium of normal size. Restoration of the atrium to its normal size resulted in ;dynamic' thresholds and responses to changes in pressure within the normal range. The changes could be explained assuming the Laplace relationship.5. This evidence supports the conclusion from previous investigations in which these techniques were used, that the increase in discharge in atrial receptors with myelinated vagal fibres could be the cause of the increase in heart rate and urine flow.


Adaptation to abrupt time shifts of the oscillator(s) controlling human circadian rhythms. 1. Thirty-six subjects in an isolation unit were subjected to time shifts of 12 hr, or of 8 hr in either direction. 2. The rhythms of body temperature and excretion of eight urinary constituents were studied before and after the shift, both on a usual nychthemeral routine and during 24 hr when they remained under constant conditions, awake, engaged in light, mainly sedentary activity, and consuming identical food and fluid every hour. 3. The rhythms on nychthemeral routine were defined by fitting cosine curves. On constant routine the rhythm after the shift was cross-correlated with the original rhythm, either with variable delay (or advance) or with an additive mixture between this variably shifted rhythm and the unshifted or a fully shifted rhythm. The process yielding the highest correlation coefficient was accepted as the best descriptor of the nature of adaptation. 4. A combination of two rhythms was observed more often for urinary sodium, chloride and phosphate than for other variables. 5. Adaptation appeared to have proceeded further after westward than eastward shifts, and this difference was particularly noticeable for urinary potassium, sodium and chloride. 6. Partial adaptation usually involved a phase delay, even after an eastward shift when a cumulative delay of 16 hr would be needed to achieve full adaptation and re-entrainment. 7. Observations under nychthemeral conditions often gave a false idea of the degree of adaptation. In particular, after an eastward shift the phase of the rhythms appeared to shift in the appropriate direction when studied under nychthemeral conditions whereas the endogenous oscillator either showed no consistent behaviour or, in the control of urate excretion, a shift in the wrong direction. 8. The implications for people undergoing time shifts, in the course of shift work or transmeridional flights, are indicated.


Mobilization of colonic kallikrein following pelvic nerve stimulation in the atropinized cat. 1. Pelvic nerve stimulation (p.n.s.) in cats induces atropine-resistant colonic vasodilatation and colonic contraction. The effects of this on cat colon are mimicked by synthetic bradykinin infusions. The present study examines the effect of p.n.s. on the activation of kallikrein, the kinin-forming enzyme present in colonic tissue and its effects on the plasma kinin system in the atropinized cat.2. Mean level (+/- S.D.) of mucosal kallikrein was found to be about 37 times higher in unstimulated colonic mucosa (300 +/- 100 ng bradykinin equivalents min(-1)g(-1)) than in the underlying muscle (8.2 +/- 6.3 ng bradykinin equiv min(-1)g(-1)).3. After a p.n.s. of 5 min, mean kallikrein level in colonic muscle was 7.3 +/- 3.5 ng bradykinin equiv min(-1)g(-1), which was not significantly different from the control muscle kallikrein. However, there was an 86% fall in mucosal kallikrein to 41.3 +/- 34.7 ng bradykinin equiv min(-1)g(-1) after 5 min p.n.s., indicating a rapid activation and secretion of mucosal kallikrein.4. Secretion of mucosal kallikrein was paralleled by specific depletion of plasma kininogen, the precursor of active kinin in blood draining the colon. The mean plasma kininogen level fell to 79 and 68% of the prestimulated value (3.1 +/- 1.1 S.D. mug bradykinin equiv per ml. plasma) after 5 and 10 min p.n.s. respectively. Total plasma protein and haematocrit remained unaltered excluding non-specific changes due to protein extravasation or haemodilution and indicating utilization of the plasma kinin precursor.5. Following 2 hr p.n.s., raised levels of kallikrein were detected in both colonic muscle (28 +/- 2.0 bradykinin equiv min(-1)g(-1)) and mucosa 434 +/- 118 ng bradykinin equiv min(-1)g(-1)). Preliminary studies using a kallikrein inhibitor indicated that the increased kallikrein levels originated from plasma.6. Direct stimulation of the parasympathetic pelvic nerve in the atropinized cat thus produced activation of the plasma kinin system in the colon and formation of free kinins may be responsible for the mucosal vasodilatation and strong motor contraction which is not blocked by large doses of atropine. The observation that prolonged stimulation causes extravasation of plasma kallikrein, a potential inflammatory mediator, into the tissues may be of clinical significance.


Directional tuning of complex cells in area 17 of the feline visual cortex. 1. Directional tuning for motion of a field of static visual noise and for motion of bar stimuli against the same stationary noise field as background was compared in eighty-four deep-layer complex cells recorded from area 17 of cats, lightly anaesthetized with N(2)O/O(2) supplemented with pentobarbitone. Detailed comparisons of monocular tuning for the dominant eye receptive field were made for seventy-two cells. Interocular, and stimulus-dependent ocular dominance differences are reported elsewhere (Hammond, 1978c, and in preparation).2. Directional bias for preferred and opposite directions of motion was enhanced with moving noise fields, compared with moving bar stimuli. Two thirds of cells directionally biased for bars, were directionally selective for noise (33/49); ten of these showed suppression of firing to noise moving in the ;null' direction. An additional twenty-three cells were directionally selective for bar stimuli and for noise, nine with suppression of firing in the null direction.3. A majority of cells (52/62) showed significant differences in preferred directions for bar stimuli and for noise; in an exceptional case, tuning for the two classes of stimuli was orthogonal. Tuning for bar stimuli was usually sharper than for noise. In cells asymmetrically tuned for bar stimuli, tuning was broader for the flank of the tuning curve closest to the preferred direction for noise. Ten cells showed similar tuning for bars and noise; tuning for the remaining ten cells was rather variable or poorly defined.22/62 cells showed bimodal directional tuning to noise, with depression of sensitivity over the range of directions to which the cell responded well with a moving bar stimulus.4. Cells were frequently more responsive to noise-field motion than to bar motion. Cells with large receptive fields showed greater sensitivity to noise than those with small fields, and were relatively more sensitive to noise than to bar stimuli.5. The results are interpreted as evidence that the directional and orientational sensitivity of complex cells are mediated by different mechanisms.