Retinal ischemia in diabetic retinopathy

Eight patients with proliferative diabetic retinopathy developed extensive retinal arteriolar and capillary obstruction. Ophthalmoscopy showed many white, thread-like retinal arterioles associated with capillary and venous dilatation. Widespread retinal arteriolar and capillary nonperfusion was demonstrated by fluorescein angiography. Ischemic maculopathy resulted in severe loss of visual acuity in some eyes. The severe degree of retinal ischemia was accompanied by optic disc pallor and neovascularization and a high incidence of rubeosis iridis with neovascular glaucoma. Patients with this variety of diabetic retinopathy have a poor prognosis of retaining useful vision.

Antibody-induced redistribution of CEA on the cell surface: utilization in separation of CEA and isoantigen A

Antibodies specific for carcinoembryonic antigen (CEA) induced polar redistribution of CEA which was expressed on the surface of human intestinal carcinoma cells grown in tissue culture. Polar redistribution occurred at 23 degrees C and 37 degrees C but not at 4 degrees C and was inhibited by sodium azide and cytochalasin B. Antibodies to isoantigen A did not react with CEA at the cell surface but did react with isoantigen A which was not redistributed by the antibody. Cells which expressed both CEA and isoantigen A were used to demonstrate that polar redistribution of CEA could be induced without altering the distribution of isoantigen A. The data indicate that CEA and isoantigen A can be expressed on the same cell as separate molecules.

Lactogenesis in the rat: an ultrastructural study of the initiation of the secretory process

Three specimens were taken from mammary glands of rats killed on the 18th and 21st days of pregnancy and on the 1st day of lactation. Ultrastructural features of the tissue were compared among rats within and between the two stages of development. The similarity among specimens from the same rats made feasible a comparison of serial biopsies obtained every 4 hr, starting on the afternoon of the 21st day of pregnancy. From the 18th to the 21st days of pregnancy, a marked increase in the amount of rough endoplasmic reticulum occurred. The alveolar cells of rats killed on both days and in biopsies obtained at 17 and 13 hr before partuirtion contained abundant small lipid droplets and vacuoles containing many protein granules with little clear fluid (stasis vacuoles). Alveolar lumina were distended with secretion by 17 hr before parturition. Between 8 and 12 hr. before parturition, the accumulated protein and lipid were rapidly extruded from the alveolar cells despite evidence of continued biosynthesis. It is suggested that active transport processes are initiated independently of milk synthesis before parturition.

Electron microscopy of the placenta and related structures of the marmoset

The marmoset has recently become an important animal in oncologic research, especially with respect to herpes deoxyribonucleic acid viral tumors. As a prototype of the primitive New World monkey, it is also valuable for the study of primate evolution. For these reasons this ultrastructural description of its placenta is presented, including the first electron micrographs of the basal plate and amnion. The main placental mass is pseudo-labyrinthine, or trabecular. The ultrastructural features of the cellular and syncytial trophoblast and endothelium closely resemble those of higher primates. The junctional region shows numerous clumps of moderately well-differentiated trophoblast, an acellular junctional zone, and a poorly developed decidual reaction. Trabecular connective tissue is sparser and transitional trophoblastic elements are less prominent than those in the human placenta. The amnion is ultrastructurally indistinguishable from that of the higher primates. Although the marmoset's placenta retains certain primitive gross and histologic features, such as the large persistent yolk sac and the trabecular condition, it is ultrastructurally quite similar to that of man.

Attention, learning, and personality during ketamine emergence: a pilot study

To analyze the memory, learning, attention, and personality effects associated with emergence from partial ketamine induction, 11 resident physicians were tested. Ketamine was found to be truly dissociative in that it seemed to impair learning of and memory for unusual word associations, at least in young physicians.

Impaired chemiluminescence during phagocytosis of opsonized bacteria

A simple technique is presented for rapid screening of leukocytes of patients suspected of having a defective intracellular mechanism for the bactericidal and digestive disposal of bacteria.

Structure and dynamics of a cave population of the Guano mite, Uroobovella coprophila (Womersley)

The biology and ecology of U. coprophila was studied in mite cultures in the laboratory and from analyses of samples taken from a heap of bat guano in a small cave chamber. The guano heap was formed over many years of cyclical roosting in the chamber by several thousand bent-winged bats, whose faeces and urine form the source of energy for the permanent community of organisms in the heap. U, coprophila is a major component of this guano community because of its exceedingly high numbers (up to 33.7 x l0*6 per square metre). Freshly defaecated bat guano was collected from the cave and used as a substrate for laboratory cultures of mites. The mites feed and mature on fungi. There are five stages in the life cycle: eggs, larvae, protonymphs, deutonymphs, and adults of both sexes. No phoretic nymphs were found. The mean duration in days of each of these stages was determined at 14,20, and 24�C. There was a positive linear relationship between temperature and the rate of development of larvae and protonymphs. Age-specific fertility and mortality were determined. Laboratory experiments supported the hypothesis that a regular supply of fresh bat guano was necessary for continuous growth and reproduction of U. coprophila. When fresh dung was not available, females ceased laying eggs and growth of the immature stages ceased. Nymphs and adults became quiescent. Annual changes in the cave population of mites and their vertical distribution in the guano heap were determined from quantitative samples of bat guano collected at regular intervals from August 1966 to July 1970. A sieve-sampling method for guano deposits is described; mites were extracted by a modified Tullgren funnel. Mites feed primarily in the surface layers of guano and move into the heap to moult. Sex ratios were found to be significantly biased towards males at most times of the year. Several generations were produced each year. These overlapped and became indistinguishable. A graphical method was used to determine instar-specific mortality of the mites. Recruitment to the population occurred when bats were present in the chamber and fresh dung was being deposited. When bats were not present, the fresh guano was used up rapidly and growth and reproduction of the mite population ceased. It is suggested that the mite population progresses through an annual cycle of four phases keyed with the annual roosting cycle of the bats and that limitation of the mite numbers is by a complex interaction between fly larvae, food, and temperature of the guano until an absolute shortage of food occurs and mites become quiescent.

Effect of antidiuretic hormone on human small intestinal water and solute transport

The effect of i.v. Pitressin (ADH) in a dose of 1 U/hr on permeability characteristics and on absorptive capacity of the normal human small intestine was investigated. The method of continuous intestinal perfusion was employed with polyethylene glycol 4000 as a nonabsorbable marker. Unidirectional flux rates of Na and H(2)O were calculated from the disappearance of (22)Na and of (3)HOH from isotonic saline solution within the intestinal lumen. Each study consisted of two successive perfusion periods: one while the subject was hydrated, the other during ADH infusion or while the subject was dehydrated. Water and sodium absorption from isotonic NaCl occurred in the hydrated state and was abolished by ADH as well as by dehydration in the jejunum. In some instances, net gain of water and sodium in the lumen occurred. In the ileum, ADH and dehydration caused a decrease in water and sodium absorption rate. By contrast, unidirectional flux into the intestinal lumen of water and sodium, as well as dextrose and D-xylose diffusion, remained unchanged by ADH. During perfusions with hypertonic urea solutions the rates of sodium and water entry into the intestine were greatly increased during i.v. ADH infusion, whereas urea loss from the study segment remained constant. ADH in the dosage used did not affect human intestinal motility. The results suggest that circulating ADH in physiologic concentrations affects the small intestine in one of two ways: increased secretion of water and salt into the lumen or direct interference with the active sodium transport mechanism.