The Gonotrophic-Age Structure of a Population of the \u3ci\u3eSimulium Venustum\u3c/i\u3e Complex (Diptera: Simuliidae) in Algonquin Park, Ontario

Eight techniques for the determination of parity and gonotrophic age were assessed for the obligatorily anautogenous blackfly-species complex, Simulium venustum Say. All females could be age-graded by the presence or absence of dilatations on the ovarioles. However, multiple dilatations on a single ovariole were not found and the Polovodova method could not be used to determine the number of completed gonotrophic cycles. Most females could be age-graded by the appearance of the Malpighian tubules, which undergo morphological changes, probably as a result of a bloodmeal. In some cases, the size of the fat body, the presence of retained (relict), mature ova and the presence of meconium in the gut could be used as accessory age-grading criteria. Insemination status, the volume of the esophageal diverticulum, and the stage of development of the terminal ovarian follicles could not be used to age-grade females. The literature of age-grading in blackflies is reviewed, with special reference to the interpretability of the Polovodova method. Seasonal changes in the gonotrophic-age structure of a population of the S. venustum complex in Algonquin Park, ON, Canada, were examined over two years. The maximal proportion of parous females in the population was 75 and 62% in the two years, respectively. There was weak evidence that parous females were more likely to host seek in the morning and nulliparous females in the afternoon. Parity declined in mid-season, due to the recruitment of newly emerged adults to the population

Remarks on Executive Action and Immigration Reform

This essay places the President\u27s executive actions on immigration last November into a larger context by providing a brief history of prosecutorial discretion in immigration cases. This essay also describes how law students at Penn State Law School used the President\u27s announcement of executive actions as a platform for local change in the State College community

Pain and peptic ulcer

Prom these varied observations on pain, spontaneous and induced, it is obvious that neither motor activity nor irritation by acid can be the sole cause of the pain of peptic ulcer. It is true that spasms of pain were observed which coincided with peristaltic waves of the duodenum in a patient with a duodenal ulcer deformity. It is also true that another patient was free of pain \?hen motility was reduced to a minimum and at a time v/hen the acid level remained high. On the other hand some patients had pain which was quite unrelated to motility. This pain would stop for 10 minutes or more and then resume while contractions continued uninterrupted. Even duodenal spasm could occur in patients with duodenal ulceration without caus¬ ing pain. It could hardly be argued that the ulcer was insensitive since a matter of a few minutes before or after the patient was in pain. During one episode of duodenal spasm a patient had pain for a minute but the pain then disappeared while the spasm continued for another few minutesIt has been suggested that acid causes pain by causing spasm (Hurst, I9H5 Kinsella, 19^4-8) but 35% of f*18 injections of 0.5% HC1 failed to produce any increase in tone or movement and the majority of these injections were followed by pain. The converse of this argument - that alkaline powders act by relaxing tone - is difficult to / 20. to sustain since 50>o of 18 injections of sodium "bicarbonate were followed "by increased tone or movement, usually with relief of pain. In one case the injection was followed' by duodenal spasm, relief of pain and spasm coinciding.The case for the acid theory of pain is not much better. Certainly in some of the experiments there was a relationship between increasing acid concentration and the onset of pain and also between decreasing acidity and relief of pain. Other experiments, however, showed no such relationship. Pain often disappeared when the acid¬ ity remained constant or even increased. Indeed pain was sometimes intermittent when no change could be detected in either acidity or motility. Relief of pain with sodium bicarbonate was usually poss¬ ible but there was sometimes a delay of 30 minutes before relief was obtained. Palmer also encountered long delays between the giving of alkali and the relief of pain. He found similar delay between the injection of acid and the onset of pain. If one has to allow for such long latent periods it makes interpretation of spontaneous pain rather difficult because the acid level in the stomach is con¬ stantly varying. Pickering took samples of gastric juice half hourly hut during this period there could have been considerable variations in acidity. Dne has seen the acid concentration rise from 2.3 mg. HCl/ml. of gastric juice to 3.35 nig. and fall again to 2 mg0 within the space of half an hour. The pain sensitivity of the ulcer may not be sufficiently great to follow such changes quickly. If pain takes some time to develop and reach its acme it is difficult to explain why it may disappear for a short time and then return while the acidity remains constant. Pain can occur in the absence of free acid as was shown in one case when there were several spasms of pain during a spell of achlorhydria lasting 38 minutes.Motility and acid may each cause pain but they obviously do nob account for all the facts. It is possible that Kinsella may be right in ascribing the intermittency of the pain to alterations in "blood flow through an ulcer area which is sensitive "because of in¬ flammation and oedema. Much, however, remains to be done to prove this theor

Alginate hydrogel has a negative impact on in vitro collagen 1 deposition by fibroblasts

Hydrogels have been widely investigated as 3D culture substrates because of their reported structural similarity to the extracellular matrix (ECM). Limited ECM deposition, however, occurs within these materials, so the resulting “tissues” bear little resemblance to those found in the body. Here matrix deposition by fibroblasts encapsulated within a calcium alginate (Ca-alg) hydrogel was investigated. Although the cells transcribed mRNA for coll Iα over a period of 3 weeks, very little collagen protein deposition was observed within the gel by histology or immunohistochemistry (IHC). Although molecular diffusion demonstrated charge dependency, this did not prevent the flux of both positively and negative charged amino acids through the gel, suggesting that the absence of ECM could not be attributed to substrate limitation. The flux of protein, however, was charge-dependent as proteins with a net negative charge passed quickly through the Ca-alg into the medium. The minimal collagen deposition within the Ca-alg was attributed to a combination of rapid movement of negatively charged procollagen through the gel and steric hindrance of fibril formation

Nasal Drug Delivery Systems: An Overview

Since ancient times, drugs have been administered via the nasal route for therapeutic and recreational purposes. The interest in, and importance, of the systemic effects of drugs administered through the nasal route, have expanded over recent decades. Intra-nasal administration of drugs offers an interesting alternative for achieving systemic therapeutic effects of drugs that are comparable to the parenteral route, which can be inconvenient at times or oral administration, which can result in unacceptably low drug bioavailability. So, it is important to understand the potential and limitations of various nasal drug delivery systems. Therefore, the aim of this review article is to discuss the various pharmaceutical dosage forms that have the potential to be utilised for local or systemic drug administration. It is intuitively expected that this review will help to understand and further to develop suitable intra-nasal formulations to achieve specific therapeutic objectives

A remark on the similarity and perturbation problems

In this note we show that Kadison's similarity problem for C*-algebras is equivalent to a problem in perturbation theory: must close C*-algebras have close commutants?Comment: 6 Pages, minor typos fixed. C. R. Acad. Sci. Canada, to appea