Hypotensive and vasodilatory activity of (+/-) 1-o-octadecyl-2-acetyl glyceryl-3-phosphorylcholine in the normotensive rat

Synthetic (+/-) 1-O-octadecyl-2-acetyl-glyceryl-3-phosphorylcholine (octadecyl-AGPC) in microgram/kg doses given intravenously effectively and potently lowered mean arterial blood pressure in conscious and anesthetized normotensive rats. The hypotensive activity was much more pronounced in the anesthetized rat than in the conscious rat. The hypotension was associated with a significant elevation in plasma renin activity (PRA). In the rat in which the hindquarters were perfused, octadecyl-AGPC given intraarterially effectively decreased the perfusion and systemic pressures in a dose-dependent manner. Pharmacological blockade with specific cholinergic, histaminergic or beta-adrenergic receptor antagonists, did not block or attenuate the octadecyl-AGPC-induced reduction in perfusion or systemic pressure. These results suggest that the hypotensive activity of octadecyl-AGPC in the normotensive rat is the result of direct vasodilation and not the result of cholinergic, histaminergic or beta-adrenergic receptor interaction.     

Some factors affecting spore replication of Nosema algerae (Microspora,Nosematidae) in Pieris brassicae (Lepidoptera)

The production of Nosema algerae spores was examined in Pieris brassicae. Spore replication in the insect host followed a logistic pattern of development. The factors studied which affected spore production and replication were dose level (5 × 10², 5 × 10³, and 5 × 10⁴ spores per insect), larval instar (fourth and fifth), and cool pretreatment of the insects at 20°C prior to inoculation compared with a constant temperature of 26°C. A three-way analysis showed the interactions between these factors. The logistic pattern of spore replication was used to explain the results.     

Comparison of ultrafiltration systems for concentration of biologicals

Ultrafiltration has been used with increasing frequency in recent years in biological laboratories for concentration, separation or purification of biological material. No data have been available on the comparison of the characteristics of Ultrafiltration systems currently in use. This study compares the filtration characteristics of four systems using commercially available membranes on suspensions and solutions: suspension of protein micelles (casein), cell debris (E. coli) and catalase solution. None of the four systems considered is found to be generally superior for all the suspensions and solutions. Vibration systems were most effective when relatively large particles were involved, while laminar flow recycling systems with high wall shear rates were best for dilute suspensions and proteins in solution. It was found that shearing inactivates enzymes in both recycle and vibration systems. It was also observed that vibration actually reduces flux in dilute solutions.     

Linear, Single-Stranded Deoxyribonucleic Acid Isolated from Kilham Rat Virus

Kilham rat virus (KRV) was grown in a rat nephroma cell line and was purified by two isopycnic centrifugations in cesium chloride. The virus contains single-stranded deoxyribonucleic acid (DNA) with a molecular weight of approximately 1.6 x 10(6). The DNA was extracted from the virion by both phenol extraction and by 2% sodium dodecyl sulfate at 50 C. KRV DNA, extracted by both procedures, was observed in an electron microscope by using a cytochrome c or diethylaminoethyldextran monolayer. The DNA was also exposed to exonuclease I, an enzyme which hydrolyzes specifically linear, single-stranded DNA. Hydrolysis of 70 to 80% of the DNA was observed. Both the enzymatic and the electron microscope studies support the conclusion that extracted KRV DNA is a single-stranded, linear molecule. The length of the DNA was measured in the electron microscope and determined to be 1.505 +/- 0.206 mum.     

Genetic Transformation of Biosynthetically Defective Neisseria gonorrhoeae Clinical Isolates

Deoxyribonucleic acid (DNA) and chemically defined media were used in transformation tests of 51 strains of Neisseria gonorrhoeae which exhibited various biosynthetic defects when isolated from patients. These auxotrophic gonococci had one or more nutritional requirements involving proline, methionine, arginine, hypoxanthine, uracil, and thiamine pyrophosphate (THPP). DNA from a clinical isolate which did not require these compounds for growth on defined medium transformed each of the auxotrophic markers of all 51 recipient populations. Ten isolates had defects involving the synthesis of THPP; four strains (designated Thp(-)) had a growth requirement that was satisfied only by THPP, whereas the requirement of six strains (designated Thi(-)) was satisfied by either thiamine or THPP. DNA from Thp(-) donors elicited transformation of Thp(-) as well as Thi(-) recipients. Reciprocally, DNA from a Thi(-) donor transformed both Thi(-) and Thp(-) recipients. Furthermore, DNA from other auxotrophic gonococci had transforming activity for some phenotypically similar auxotrophic recipients. The findings indicate the existence of various nonidentical genetic defects which block reactions in the biosynthesis of proline, methionine, arginine, hypoxanthine, and THPP. Routine cultures from patients with gonorrhea were the source of these auxotrophic strains of N. gonorrhoeae; the various nutritional requirements were identified by a recently described system of gonococcal auxotyping. The transformation test results verify the hereditary basis of the auxotypes, establish that many different mutations exist in potentially virulent gonococci, and illustrate the value of these auxotrophic mutants for studies of the genetic structure and evolution of natural populations of gonococci.     

The occurrence of fungi in activated sludge

The population of a biological system in a sewage treatment plant is formed of a fortuitous assemblage of microorganisms, members of which are continually dropped out while additional members are recruited. Many of these organisms are active throughout the year. Fewer yeasts than filamentous fungi are found by the plating technique. The population is about evenly divided between species producing their spores in dry states and in wet states. The fungus population includes species which under certain circumstances are able to use a wide variety of substrates from simple sugars to complex carbohydrates and hydrocarbons.

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Zusammenfassung Die Population eines biologischen Systems in einem Kloakenwasser-Behandlungs-werk ist durch ein zufälliges Zusammentreffen von Mikroorganismen geformt, deren Mitglieder fortwährend ausfallen, während andere hinzukommen. Viele dieser Mikroorganismen sind während des ganzen Jahres aktiv. Weniger Hefen denn Fadenpilze sind mit der Plattentechnique gefunden. Die Population ist ungefähr gleichmäßig unter den Arten verteilt, die die Sporen in trockenem wie in feuchtem Zustand produzieren. Die Pilzpopulation umfaßt Arten, die unter gewissen Umständen fähig sind, eine große Varietät von Nährmaterial, von einfachen wie auch komplexen Kohlenstoffhydraten und Kohlenstoffhydraten zu benutzen.

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Much of the material included here was Presented at the 23rd Industrial Waste Conference Purdue University, Lafayette, Indiana May 7–9, 1968     

Burning-Feet Syndrome: Case Due to Malabsorption and Responding to Riboflavine

A woman with the burning-feet syndrome was found on investigation to have malabsorption. The syndrome responded rapidly to intramuscular injections of 6 mg. of riboflavine daily. It is suggested that deficiency of this substance, due to malabsorption and aggravated by a defective diet and repeated pregnancies, was responsible for the syndrome in this case.     

Pyrogenic Responses to Staphylococcal Enterotoxins A and B in Cats

Pyrogenic responses, ranging up to 4.8 F, were induced in cats by oral administration of highly purified staphylococcal enterotoxin B in doses from 10 to 100 mug/kg. Fever was a more sensitive indicator of intoxication than was emesis. Highly purified preparations of enterotoxin A, whether administered intravenously (0.01 to 1.0 mug/kg), orally (10 to 25 mug/kg), or into the cerebral ventricles (0.005 to 0.020 mug in 0.20 ml), were also pyrogenic in cats. Tolerance to the pyrogenic activity was produced by repeated intravenous injection of a given dose of enterotoxin A but not by repeated intracerebroventricular injection. Enterotoxin A was more potent than enterotoxin B after intravenous injection in causing both fever and emesis. Cross-tolerance could not be demonstrated between enterotoxin A and enterotoxin B or Salmonella typhosa endotoxin. This lack of cross-tolerance plus the inability of large oral doses (100 to 4,700 mug/kg) of endotoxin to cause fever or emesis indicate that the reported responses were attributable to the specific toxins administered and not to contamination by other pyrogens.     

POLYCYTHEMIA VERA—Peripheral Vascular Manifestations

The presenting manifestations of polycythemia vera are often complications involving the vascular system. These include myocardial infarction, cerebro-vascular accidents and ischemic changes in the extremities.The concept of increased atherogenesis in cases of polycythemia vera has been questioned. A possible mechanism by which small, otherwise subclinical atheromatous plaques produce ischemic symptoms in patients with polycythemia vera is discussed. The blood in polycythemic patients has been shown to have an increased viscosity resulting in a prolonged circulation time. If a small atheromatous plaque is present in association with increased blood viscosity, this combination may well produce ischemic symptoms. This explains why treatment of polycythemia vera, with restoration of blood to normal viscosity, often reverses the patient''s ischemic symptoms.Two cases of polycythemia vera here reported, in which the presenting manifestations were gangrenous extremities, emphasize the need for prompt diagnosis and treatment of polycythemia vera. In the first case, early recognition and treatment of polycythemia vera successfully reversed the ischemic changes in the extremities, while failure of early recognition and treatment in the second case resulted in two major amputations.