Thesis (Ph. D.)--University OF MICHIGAN.

Thèse-Ecole de médecine de Paris.

Thesis (Ph.D.)--New York University, Graduate School of Arts and Science, 2006. / Typescript. Includes bibliographical references (leaves 288-300). Also available in electronic format on the World Wide Web. Access restricted to users affiliated with licensed institutions.

<p> Two distinct studies were undertaken in order to examine the effects that both external weight distribution, and internal, bike-rider interface forces had on cyclists. The first section of the study looked at the bike-rider interface forces, and how they fluctuate during normal cycling; as well as how they vary with changes in rider power output, hand position, and cadence. In order to analyze these changes in isolation, three different studies were undertaken. The studies each examined 10 USAC Category 3 or better riders who were tested for 6 minute trials. Riders were tested with their hands on the tops, drops and hoods, with cadences of 60-90 RPM, and power outputs of 1-4 watts per kg. It was found that for each 1 W/kg power output increase, saddle forces decreased by 5.2 percentage points and bottom bracket forces increased by 3.3 percentage points. Cadence did not affect bike-rider interface forces. Shifting a rider's hands from the hoods to the tops and the drops increased the stem force by approximately 2 and 4 percentage points, respectively. </p><p> The weight distribution study examined the effect of different bike fitting procedures on the bike-rider system, front/rear wheel, weight distribution. The study compared 13 amateur and 14 professional riders with four different fitting techniques. It was found that the Ret&uuml;l Fit weight distribution was 44.7%/55.3% front/rear and the Body Geometry Fit was 32.5%/61.5% front/rear. It was also found that the professional fit and the self-fit 40.4%/59.6%, and 38.5%/61.5% respectively, are similar (p=.9239).</p>

The history of science has frequently shown that a problem discarded in one period lies dormant for a certain interval of time, only to be reawakened, refreshed, and brought to its natural solution with the aid of more advanced technical instrumentation. The German Physiologist Friedrich Merkel (1883), in the introduction to his thesis on Salivary Ducts wrote:- “The fact that organs which are secreting show microscopic changes in the structure of the secretory cells leads to a new approach in histological research. Examination of secretory organs is unthinkable without evaluation of the specific Physiological state and its relation to the morphology. This is necessary in all fields of biological research”.

During the past decade, several chemical derivatives of the phenothiazine nucleus have been synthesized in France, and their various pharmacological actions investigated. As a result of these studies, a number of new compounds of this type have already been introduced as therapeutic agents. The drugs in this series are of special pharmacological interest because of the wide scope of physiological functions which they have been reported to affect, and this is particularly so in respect to the chlorophenothiazine derivative, known as chlorpromazlne.

The strikng similarity that Elliot (1904) discovered between the effects of adrenaline and sympathetic stimulation led him to suggest that the sympathetic nervous system might act by releasing small quantities of adrenaline from its post-ganglionic terminations. This was the first formulation of the idea of chemical transmission: two years later W. E. Dixon proposed that parasympathetic nerves similarly might liberate a chemical transmitter of their effects, and he suggested muscarine to be the substance involved (Dixon, 1906).

This work is concerned with a study of the action of veratrine sulphate on the electrical responses of skeletal muscle. All the experiments performed in this study involve the use of frog’s skeletal muscle. However, because of the similarity of the actions of this alkaloid on nerve and muscle, much of the discussion and many of the references given will concern studies performed on nerve fiber preparations. About 10 years ago, an excellent review on the pharmacology of the veratrum alkaloids appeared (Krayer and Aches on, 1946).

Electrical stimulation of the cervical sympathetic trunk or administering adrenaline or noradrenaline leads to pronounced changes in the composition of saliva obtained from the cat's submaxillary gland by simultaneous and/or subsequent chorda stimulation. The concentration of nonelectrolytes found in "normal" parasympathetic saliva rises and the gland becomes permeable to larger molecule: sucrose (MRD = 3.9 A) and raffinose (MRD = 5.1 A) diffuse freely from the plasma into the saliva whereas normally a radius of 3.2 A seems to be limiting. Molecules with radii exceeding 6A show restricted diffusion and inulin (MRD = 14.8 A) does not appear in the saliva under any circumstances.

The term folic acid was first introduced by Mitchell et al (1) in 1941. It is used variously to refer to a specific compound (Figure 1) or to a general family of conjugated pterins and pteridines possessing folate biological activity. The parent compound illustrated in Figure 1 is composed of 2-amino-4-hydroxy-6-methylpteridine, p-aminobenzoic acid, and L-glutamic acid (2) and is also referred to as pteroylglutamic acid.