A Friedman-type Test for Circular Data and Arbitrary Cell Frequencies

To analyse directional data resulting from unifactorial block designs a Friedman-type test is described and the exact and asymptotical properties of the defined test statistic are considered.     

Atrial natriuretic factor alters autonomic interactions in the control of heart rate in conscious rats

Regulation of heart rate was studied in rats receiving either i.v. saline at 64 microL/min or synthetic 28-residue rat atrial natriuretic peptide (ANF) at a dose sufficient to decrease mean arterial blood pressure by 10%. Autonomic influences were deduced from steady-state heart rate responses of each group to propranolol, atropine, or propranolol and atropine combined. A multiplicative model of heart rate control was used to derive quantitatively from the data the modulation of intrinsic heart rate by sympathetic and parasympathetic mechanisms. Animals receiving ANF showed a lower heart rate than control animals. This relative bradycardia was abolished by atropine. Blocking of sympathetic effects with propranolol had no effect on basal heart rate in either group, and atropinization led to significant increases in heart rate in both groups of rats. Mathematical analysis of the results showed that the bradycardia produced by ANF was due predominantly to a reduced intrinsic heart rate and to enhanced vagal inhibition of postganglionic sympathetic activity. Parasympathetic contribution to heart rate in the absence of sympathetic activity was negligible in control rats and small during ANF. We conclude that the major influences of ANF on heart rate control are a decrease of intrinsic heart rate and enhanced parasympathetic inhibition of postganglionic presynaptic sympathetic activity.     

Resolution of Conflicting Signals at the Single-Cell Level in the Regulation of Cyanobacterial Photosynthesis and Nitrogen Fixation

Unicellular, diazotrophic cyanobacteria temporally separate dinitrogen (N₂) fixation and photosynthesis to prevent inactivation of the nitrogenase by oxygen. This temporal segregation is regulated by a circadian clock with oscillating activities of N₂ fixation in the dark and photosynthesis in the light. On the population level, this separation is not always complete, since the two processes can overlap during transitions from dark to light. How do single cells avoid inactivation of nitrogenase during these periods? One possibility is that phenotypic heterogeneity in populations leads to segregation of the two processes. Here, we measured N₂ fixation and photosynthesis of individual cells using nanometer-scale secondary ion mass spectrometry (nanoSIMS) to assess both processes in a culture of the unicellular, diazotrophic cyanobacterium Crocosphaera watsonii during a dark-light and a continuous light phase. We compared single-cell rates with bulk rates and gene expression profiles. During the regular dark and light phases, C. watsonii exhibited the temporal segregation of N₂ fixation and photosynthesis commonly observed. However, N₂ fixation and photosynthesis were concurrently measurable at the population level during the subjective dark phase in which cells were kept in the light rather than returned to the expected dark phase. At the single-cell level, though, cells discriminated against either one of the two processes. Cells that showed high levels of photosynthesis had low nitrogen fixing activities, and vice versa. These results suggest that, under ambiguous environmental signals, single cells discriminate against either photosynthesis or nitrogen fixation, and thereby might reduce costs associated with running incompatible processes in the same cell.     

Effect of the phosphonic acid derivatives ethephon and trichlorphon on the incorporation in vivo of (14C)-acetate into cholesterol and other lipids in rats

The effect of the phosphonic acid derivatives Ethephon and Trichlorphon on the incorporation of 14C-labelled acetate into lipids especially cholesterol was investigated. Adult Wistar rats were fed for 7 days diets containing 50 and 500 ppm, respectively, of the phosphonic acid derivatives. Both compounds caused a significant increase of the 14C-activity in lipids of serum, liver, heart, and brain. The effect of Ethephon was significantly more intense than that of Trichlorphon. The important finding was the Ethephon-induced increase of the [14C]-acetate incorporation into cholesterol which continued across all the tissues studied.     

Programming of poliovirus inhibition of deoxyribonucleic acid synthesis in HeLa cells

Ackermann, W. W. (The University of Michigan, Ann Arbor), and D. Wahl. Programming of poliovirus inhibition of deoxyribonucleic acid synthesis in HeLa cells. J. Bacteriol. 92:1051-1054. 1966.-Deletion of arginine from a culture medium reduced the rate of deoxyribonucleic acid (DNA) synthesis in uninfected HeLa cells. The normal rate was promptly restored by addition of arginine. Deletion of arginine also prevented poliovirus from inhibiting DNA synthesis in HeLa cells. However, the inhibitory potential of the infection and the capacity of the host cell for stimulation with regard to DNA synthesis were both retained in arginine-depleted cells which were infected. Upon addition of arginine late in the infection, DNA synthesis was first stimulated and then inhibited.     

The seeds of Loasaceae subfam. Loasoideae (Cornales) II: Seed morphology of “South Andean Loasas” (Loasa, Caiophora, Scyphanthus and Blumenbachia)

South Andean Loasas (Blumenbachia, Caiophora, Loasa, Scyphanthus) are a monophyletic group of taxa within Loasaceae subfam. Loasoideae, comprising some 100 species, 49 of which are investigated here. They retain a many-layered testa in the mature seeds and usually have passive transfer testas with complex, spongiose wall outgrowths. Additional modifications concern the undulations of the testa epidermis, presence or absence of the outer periclinal wall, secondary sculpturing, the presence or absence of spines, warts and finally spongiose structures on the anticlinal walls of the testa epidermis and the inner periclinal wall. Seeds of the widespread “deeply pitted” type are plesiomorphic, while various subclades of South Andean Loasas have derivations underscoring their relationships and confirming the relationships found with molecular markers and other morphological characters. The genus Blumenbachia has either seeds with a many-layered testa forming longitudinal lamellae (sect. Angulatae), or balloon seeds with a loose outer testa layer and spongiose wall outgrowths on the inner periclinal walls (sect. Blumenbachia and sect. Gripidea) and is clearly monophyletic. Loasa s.str. (ser. Loasa, ser. Macrospermae, ser. Floribundae, ser. Deserticolae) is characterized by the presence of a subterminal hilum or hilar scar and one subgroup (ser. Loasa, ser. Macrospermae) by very large and heavy seeds with a collapsed testa. L. ser. Pinnatae, ser. Acaules, ser. Volubiles, Scyphanthus and Caiophora share more or less one seed types with minor modifications. Within Caiophora various derivations are observed, of which the gradual loss of the secondary sculpture of the inner periclinal wall is the most striking one. Anemochoria is the most widespread dispersal mechanism in South Andean Loasas and is achieved in at least five structurally different ways.     

Effects of Formalin-Inactivated Respiratory Syncytial Virus (FI-RSV) in the Perinatal Lamb Model of RSV

Respiratory syncytial virus (RSV) is the most frequent cause of bronchiolitis in infants and children worldwide. There are currently no licensed vaccines or effective antivirals. The lack of a vaccine is partly due to increased caution following the aftermath of a failed clinical trial of a formalin-inactivated RSV vaccine (FI-RSV) conducted in the 1960’s that led to enhanced disease, necessitating hospitalization of 80% of vaccine recipients and resulting in two fatalities. Perinatal lamb lungs are similar in size, structure and physiology to those of human infants and are susceptible to human strains of RSV that induce similar lesions as those observed in infected human infants. We sought to determine if perinatal lambs immunized with FI-RSV would develop key features of vaccine-enhanced disease. This was tested in colostrum-deprived lambs immunized at 3–5 days of age with FI-RSV followed two weeks later by RSV infection. The FI-RSV-vaccinated lambs exhibited several key features of RSV vaccine-enhanced disease, including reduced RSV titers in bronchoalveolar lavage fluid and lung, and increased infiltration of peribronchiolar and perivascular lymphocytes compared to lambs either undergoing an acute RSV infection or naïve controls; all features of RSV vaccine-enhanced disease. These results represent a first step proof-of-principle demonstration that the lamb can develop altered responses to RSV following FI-RSV vaccination. The lamb model may be useful for future mechanistic studies as well as the assessment of RSV vaccines designed for infants.     

The use of fine-wire EMG to investigate shoulder muscle recruitment patterns during cello bowing: The results of a pilot study

The physical mechanics of music making is important both in the prevention of injuries and in guiding how music is performed and taught. Electromyography has potential as a resource in understanding the loads involved in instrumental playing; however, only a small number of projects have been undertaken, and little is understood on the muscle activity used during bowing on string instruments. This study aimed to measure the muscle activity at the bowing shoulder of a cellist during cello playing and to establish if fine-wire EMG is useful in understanding muscle recruitment in string players without interfering with normal playing ability. This project used a combination of fine-wire and surface EMG to evaluate the muscular load placed on the right shoulder of a professional cellist whilst playing a set of various bowing exercises. The results indicated that different bowing techniques produced statistically different muscle activity levels, with the supraspinatus muscle in particular maintaining higher mean contraction (20% MVC) during all bowing patterns tested. Fine-wire EMG was useful in measuring shoulder muscle load and did not interfere with normal playing technique of the subject. Overall, the study presents a working protocol from which future studies may be able conduct further research.