The effect of salts on the ionisation of gelatin

The effect of the addition of sodium chloride to gelatin solutions is shown from the Donnan relationship to increase the ionisation of the gelatin, the increase produced in acid solutions reaching a maximum at about 1/1000 molar salt concentration. This effect is attributed to the formation of complex ions. From the similar action of calcium and copper chlorides the effective combining power of gelatin for complex positive ion formation is deduced. The bearing of complex ion formation on the zwitter-ionic structure and solubility phenomena of proteins is pointed out

On the plant growth hormone produced by Rhizopus suinus

Since it was first discovered that cell elongation in the Avena coleoptile is controlled by a hormone, our understanding of the nature and rôle of this substance has progressed considerably. Apart from the elucidation of its functions in promoting growth, tropisms, and other reactions of the plant, the chemical nature of the substance has been extensively studied. The active substance produced by cultures of the mold Rhizopus suinus was shown by Nielsen (1930) to be ether-soluble, and by Dolk and Thimann (1932) to be an unsaturated organic acid, decomposed by strong acids but not by alkalies, and readily inactivated by oxidation. Its dissociation constant, as measured by Dolk and Thimann, is 10^-4.75. Previously, Went (1928) had shown the molecular weight of the active substance in Avena coleoptiles to be about 376. The active substance in human urine was isolated by Kögl and Haagen-Smit (1931) and by Kögl, Haagen-Smit, and Erxleben (1933), and shown to be an acid, C17H28O(OH)COOH (auxin A), whose lactone is also active, while from malt these workers later isolated (1933) a ketohydroxy acid, C17H28O(OH)COOH (auxin B), which had the same activity per unit weight. On account of the rather small amount of substance available from Rhizopus cultures, and also since the bulk of the partially purified product was lost through spontaneous inactivation (see section, “Concluding stages”), the chemical investigation of the active substance, begun earlier, was dropped. However, the many experiments on purification which had meanwhile been carried out showed that the active substance from Rhizopus did not behave in quite the same way as that from urine. Recently, however, it was shown by Kögl, Erxleben, and Haagen-Smit (1934) that there is in urine a second active substance, identical with β-indolylacetic acid, and Kögl and Kostermans (1934) showed that the molecular weight of the substance produced by Aspergillus and by Rhizopus is that of β-indolylacetic acid rather than that of the C18 compounds. Since preparations from Rhixopus have been extensively used for physiological work, both in this laboratory and elsewhere, the exact nature of the active substance is of considerable interest. The present paper will give evidence that the active substance produced by Rhizopus suinus is in fact β-indolylacetic acid. Identification by the preparation of derivatives and by mixed melting points with the pure synthetic substance was not possible on account of the small amount of material available. Nevertheless, the evidence given below is fairly conclusive. The method of purification, since it differs to some extent from that adopted by Kögl and his coworkers, will also be outlined. Finally, it will be shown that some of the peculiar conditions previously found to be necessary for the production of this growth substance (Thimann and Dolk, 1933) find a simple explanation on this basis

Studies on the growth hormone of plants. VI. The distribution of the growth substance in plant tissues

1. It is shown that when plant tissues are ground with water the growth substance contained therein is inactivated by the oxidizing enzymes. 2. A simple method of extraction is described which enables the quantitative determination of growth substance in such tissues. 3. The amount and distribution of growth substance in the Avena coleoptile is determined by this method, and it is shown that while the substance does not diffuse out from the lower parts of the coleoptile, it is nevertheless present in considerable amounts, the concentration decreasing steadily with the distance from the tip. 4. Growth substance is also present in considerable amounts in Avena roots, and here also its concentration decreases steadily with distance from the tip. 5. The amount of growth substance diffusing out of root tips into dextrose agar, even during long periods of time, is not greater than the amount obtainable by direct extraction. Actual production in the root tip therefore either does not take place at all, or else takes place under quite different conditions from the production in the tip of the coleoptile

Healthcare Ethics During a Pandemic

As clinicians and support personnel struggle with their responsibilities to treat during the current COVID-19 pandemic, several ethical issues have emerged. Will healthcare workers and support staff fulfill their duty to treat in the face of high risks? Will institutional and government leaders at all levels do the right things to help alleviate healthcare workers risks and fears? Will physicians be willing to make hard, resource-allocation decisions if they cannot first husband or improvise alternatives? With our healthcare facilities and governments unprepared for this inevitable disaster, front-line doctors, advanced providers, nurses, EMS, and support personnel  struggle with acute shortages of equipment—both to treat patients and  protect themselves. With their personal and possibly their family’s lives and health at risk, they must weigh the option of continuing to work or retreat to safety. This decision, made daily, is based on professional and personal values, how they perceive existing risks—including available protective measures, and their perception of the level and transparency of information they receive. Often, while clinicians get this information, support personnel do not, leading to absenteeism and deteriorating healthcare services. Leadership can use good risk communication (complete, widely transmitted, and transparent) to align healthcare workers’ risk perceptions with reality. They also can address the common problems healthcare workers must overcome to continue working (ie, risk mitigation techniques). Physicians, if they cannot sufficiently husband or improvise lifesaving resources, will have to face difficult triage decisions. Ideally, they will use a predetermined plan, probably based on the principles of Utilitarianism (maximizing the greatest good) and derived from professional and community input. Unfortunately, none of these plans is optimal

Alternative Care Sites: An Option in Disasters

During the current COVID-19 pandemic, the limited surge capacity of the healthcare system is being quickly overwhelmed. Similar scenarios play out when an institution’s systems fail, or when local or regional disasters occur. In these situations, it becomes necessary to use one or more alternative care sites (ACS). Situated in a variety of non-healthcare structures, ACS may be used for ambulatory, acute, subacute, or chronic care. Developing alternative care facilities is the disaster-planning step that moves communities from talking to doing. This commitment pays real dividends if a disaster of any magnitude strikes. This paper discusses the basic criteria for selecting, establishing and ultimately closing an ACS, difficulties of administration, staffing, security, and providing basic supplies and equipment

Studies on the growth hormone of plants VII. The fate of growth substance in the plant and the nature of the growth process

Since the early work of Went (1928), it has been known that the growth substance of the Avena coleoptile may be obtained in the usual way, i.e. by diffusion into agar blocks, only from that part of the plant which produces it, namely the tip. The hormone is not recoverable in this way from those parts of the plant, such as the lower zones, which only make use of it. Recent work (Thimann, 1934) has, however, shown that by extraction with chloroform some growth substance is recoverable from the lower zones of the coleoptile. The results of this extraction method confirmed the earlier view that there is a marked concentration gradient of growth substance from tip to base

The cupric complexes of glycine and of alanine

The following report is the first of a projected series of studies of the physical chemistry of the compounds of the heavy metals, particularly of copper and of iron, with substances of biological importance. These studies are invited by the accumulation in recent years of examples of the importance of the heavy metals in biological chemistry

Development of Eye Colors in Drosophila: Extraction of the Diffusible Substances Concerned

The development of eye color in Drosophila is known to involve special diffusible substances [1,2]. A genetically vermilion (v) eye will develop wild-type eye color if it is supplied with v+ substance by transplantation or by injection of body fluid of wild type flies. Similarly a genetically cinnabar (cn) eye will develop the color characteristic of wild type if it is supplied with cn+ substance. The present paper summarizes preliminary experiments made to learn something of the nature of the two substances just mentioned. During the course of our studies, Ephrussi and Harnly [3] have shown that pupal fluid can be freed of living cells by freezing in liquid air without destroying the v+ and cn+ substances. Khouvine, Ephrussi and Harnly [4] have shown further that these substances can be extracted from Calliphora pupae with 95 per cent alcohol-ether mixtures and with 95 per cent alcohol but not with pure ether. They conclude that these substances are not proteins or enzymes, a conclusion confirmed by our work