Bivariate optimization of pedalling rate and crank arm length in cycling

The contribution of this paper is a bivariate optimization of cycling performance. Relying on a biomechanical model of the lower limb, a cost function derived from the joint moments developed during cycling is computed. At constant average power, both pedalling rate (i.e. rpm) and crank arm length are systematically varied to explore the relation between these variables and the cost function. A crank arm length of 170 mm and pedalling rate of 100 rpm correspond closely to the cost function minimum. In cycling situations where the rpm deviates from 100 rpm, however, crank arms of length other than 170 mm yield minimum cost function values. In addition, the sensitivity of optimization results to both increased power and anthropometric parameter variations is examined. At increased power, the cost function minimum is more strongly related to the pedalling rate, with higher pedalling rates corresponding to the minimum. Anthropometric parameter variations influence the results significantly. In general it is found that the cost function minimum for tall people occurs at longer crank arm lengths and lower pedalling rates than the length and rate for short people.     

Comparative permeability of canine visceral and parietal pleura

To determine the permeability of canine pleural mesothelium, visceral and intercostal parietal pleura from mongrel dogs was carefully stripped from the underlying tissue and mounted as a planar sheet in a Ussing-type chamber. The hydraulic conductivity (Lp) was determined from the rate of volume flux in response to hydrostatic pressure gradients applied to either the mucosal or serosal surface of the pleural membrane. The diffusional permeability (Pd) of radiolabeled water, sucrose, inulin, and albumin was determined under equilibrium conditions from the unidirectional tracer flux. The Lp of the visceral pleura was 0.39 +/- 0.032 (SE) X 10(-4) ml.s-1.cmH2O-1.cm-2 and that Lp of parietal pleura was 1.93 +/- 0.93 X 10(-4) ml.s-1.cmH2O-1.cm-2 (P less than 0.001). The Pd of the visceral pleura ranged from 12.21 +/- 0.45 X 10(-4) cm/s for 3H2O to 0.34 +/- 0.03 X 10(-4) cm/s for [3H]albumin. The Pd of the parietal pleura for water and sucrose was similar to that of the visceral membrane, whereas its Pd for the larger inulin and albumin molecules was greater than that of visceral pleura (P less than 0.01). A spontaneous potential difference could not be detected across either membrane. The relatively higher parietal pleural Lp and Pd for larger solutes is probably due to the presence of stomata in this membrane. These results indicate that both the parietal and the visceral pleura are extremely permeable tissues which offer little resistance to water and solute flux.     

Human debrisoquine 4-hydroxylase (P450IID1): cDNA and deduced amino acid sequence and assignment of the CYP2D locus to chromosome 22

The enzyme P450db1 (db1) is responsible for the common human defect in drug oxidation known as the "debrisoquine/sparteine polymorphism." Polyclonal antibody against the rat db1 protein was used to screen a human liver lambda gt11 library for the db1 cDNA clone. A cDNA containing the full protein coding sequence was isolated; the deduced NH2-terminal sequence of this cDNA was identical to that derived from direct sequencing of the purified human db1 protein. Comparison of the human db1 with rat db1 revealed 71 and 73% similarities of nucleotides and amino acids, respectively. By use of human-rodent somatic cell hybrids the db1 gene was localized to human chromosome 22 (CYP2D locus).     

Functional morphology of the neuroendocrine sodium influx-stimulating peptide system of the pond snail,Lymnaea stagnalis,studied by in situ hybridization and immunocytochemistry

Summary The functional morphology of the neuroendocrine system producing sodium influx-stimulating (SIS) peptide in the pond snail, Lymnaea stagnalis, was studied by in situ hybridization and immunocytochemistry. The SIS-peptide, which is 76 amino acids long, stimulates sodium uptake from the ambient medium. Two synthetic DNA probes were used for in situ hybridization. The nucleotide sequences were chosen from the cDNA structure; they encode amino acids 8–17 and 64–73, respectively. SIS-peptide sequences 10–20 and 67–76 were synthesized and antibodies were raised to them and affinity-purified. In addition to these antibodies, a monoclonal antibody raised to a bioactive, high-pressure liquid chromatography (HPLC)-purified brain extract was used for immunocytochemistry. Paraffin sections of central nervous systems and of whole snails were studied. The SIS-peptide system could be identified as the previously described yellow cell (YC) system by comparing alternate sections treated with the DNA probes, stained with the antibodies, or stained with alcian blue-alcian yellow. SIS-peptide neurons (45) occur in the ganglia of the visceral ring and in the proximal parts of visceral nerves. Axons run in the nerves of these and in several nerves of other ganglia. Numerous axon branches penetrate the perineurium forming a vast central neurohemal area. The SIS-peptide system innervates the pericardium, the nephridial gland, the reno-pericardial canal, the ureter, the spermoviduct and gonadal acini, the anterior aorta, the ventral buccal artery, and the penis protractor muscle. The morphology of the system is discussed in relation to the process of sodium ion uptake from the ambient medium and from pro-urine, and to that of regulating blood pressure. In the central nervous system and other organs, neurons and axons not labeled with the DNA probes, but immunoreactive to one or two of the antibodies, were observed. It seems unlikely that these elements are functionally related to the SIS-peptide system.     

Auditory assessment of avian predator threat in semi-captive ringtailed lemurs (Lemur catta)

Antiraptor responses from forest-living ringtailed lemurs to advertisement calls of naturally-occurring red-tailed hawks suggested that the lemurs discriminated these calls from other environmental sounds. A series of playback experiments, using real animal sounds and synthetic sound probes, was conducted to investigate the acoustic basis of this putative discrimination. Two semi-captive groups of ringtails served as study subjects: one group had many years of experience living in the forest, whereas the other group had relatively little such experience. Responses to playbacks suggested that both groups used the same acoustic criteria to discriminate “calls of large hawks” from other sounds, but the range of auditory stimuli that evoked antiraptor responses was broader for the experienced group than for the inexperienced group. Although several interpretations of the experimental results are possible, one that seems particularly compatible with the data is the “prototype” concept of stimulus categorization.     

Morphology and structural organization of Haller's organ during postembryonic development ofArgas (Persicargas) walkerae (Ixodoidea: Argasidae)

Scanning-electron-microscopic investigations of Haller's organ in larvae, nymphs I, II, III and IV, and male and female adultArgas (Persicargas) walkerae ticks showed that morphology and structural organization change during postembryonic development. Stage-dependent differences existed regarding setal numbers of the anterior pit as well as formation and reticulation of cuticular projections in the capsule cavity. The anterior pit increased in size in the course of postembryonic development. It contained only seven setae in larvae, one conical, setiform and grooved seta each as well as two porose and fine setae. Nymphs I, II, III and IV and adult ticks had equal numbers of setae; however, one additional unilaterally serrate and grooved seta each were present. Setal length increased continuously during postembryonic development and attained maximum values in adult ticks. The capsule consisted of roof and cavity and was located distinctly lateral in larvae, slightly lateral in nymphs I and II, and in all other stages directly on the longitudinal axis of tarsus. The capsule roof showed a reticular structure. The slit-like main aperture was located peripherally and arranged transversally to the longitudinal axis of tarsus I in larvae. Nymphs and adult ticks had a central, circular main aperture. Stage-dependent cuticular projections of varying form protruded into the capsule cavity. Larvae had only single, free-standing projections which ramified slightly and communicated with each other. Projections were more heavily reticulated in nymphs I and II. In nymphs III and IV as well as male and female adult ticks, a long centrally situated tube of reticular appearance was seen, which was supported by a large number of radially organized and interlocking pillars and communicated with the capsule roof. In all tick stages there were always four porose setae present, arranged on the capsule floor.     

Cell type-specific gene expression in the Drosophila melanogaster male accessory gland.

The accessory gland of the male Drosophila melanogaster plays a vital role in reproduction. This secretory organ synthesizes products that are transferred to the female and are necessary to elicit the proper physiological and behavioral responses in the female. The accessory gland is composed of two morphologically distinct secretory cell types, the main cells and the secondary cells. Previous studies identified some genes expressed in main cells or in all accessory gland cells. In this paper we use P-element mediated enhancer traps to examine gene expression in the accessory gland. We show that, in addition to genes expressed in main cells only or in all accessory gland secretory cells, there are genes expressed specifically in secondary cells. Each cell type is uniform in the expression of its genes. Our results demonstrate that the two cell types are not only morphologically distinct but also biochemically distinct. We also show that the two cell types differ in their regulation of gene expression in response to mating activity.     

Effects of phosphorothioate capping on antisense oligonucleotide stability, hybridization and antiviral efficacy versus herpes simplex virus infection.

Efforts have been made to improve the biological stability of phosphodiester (PO) oligonucleotides by the addition of various modifications to either the 3', 5' or both the 3' and 5' ends of an oligonucleotide. ISIS 1080, a phosphorothioate (PS) 21-mer oligonucleotide complementary to the internal AUG codon of UL13 mRNA in HSV-1, reduces the infectious yield of HSV-1 in HeLa cells to 9.0% +/- 11%. PO analogs of ISIS 1080 containing three PS linkages placed on the 3' (ISIS 1365), 5' (ISIS 1370), both the 3' and 5' (ISIS 1364) ends or with four linkages in the middle (ISIS 1400) demonstrated reduced antiviral efficacy compared to fully PS ISIS 1080. Thermal denaturation profiles demonstrated that these oligonucleotides hybridized to complementary DNA or RNA with equivalent binding affinities. All were able to support E. coli RNAse H cleavage of the HSV mRNA to which they were targeted. The stability of the congeners in cell culture medium containing 10% fetal calf serum (FCS), HeLa cytosolic extract, HeLa nuclear extract and in intact HeLa cells revealed that ISIS 1080 was most resistant to nucleolytic digestion through 48 hours. Partial PS oligonucleotides exhibited increased degradation compared to the fully thioated oligonucleotide by exonuclease activity in FCS and endonuclease activity in cell extracts or intact cells. Thus, the reduced efficacy of partial compared to fully PS oligonucleotides against HSV-1 in HeLa cells may result from increased degradation of the mixed PO/PS oligonucleotides.