The existence of a second route for the transfer of certain glycoproteins from the circulation into the liver.

Oligosaccharide chains of agalactoorosomucoid, α₁-acid glycoprotein from which sialic acid and galactose have been sequentially removed, terminate in N-acetylglucosaminyl residues. This protein is rapidly transferred from the circulation into the liver by a route distinct from that previously demonstrated for a number of galactosyl terminating glycoproteins.     

Isoproterenol-induced, lymphocyte-dependent hyperplasia of mouse salivary glands--a possible analog of a syngeneic mixed lymphocyte culture in vivo

T-cell phenotype that regulates isoproterenol-induced lymphocyte-dependent hyperplasia of mouse salivary glands and conditions of its activation has been investigated. Stimulated Thy-1 and Ly-1-positive cell populations proliferated in the medium supplemented with both interleukin-1 (IL-1) and interleukin-2 (IL-2). The inhibiting population was Thy-1 and Ly-2-positive, proliferating only in IL-2-containing medium. Both regulatory cell properties and the character of their activation are similar to those of lymphocytes that regulate syngeneic mixed lymphocyte culture. The regularities shown may reflect important processes of cell proliferation regulation in multicellular organisms.     

Infection with Wolbachia does not influence crossing-over in Drosophila melanogaster

The influence of endosymbiotic bacterium Wolbachia on the recombination processes in the sex chromosome of Drosophila melanogaster on the region between white and cut genes has been studied. The analysis of the crossing-over frequency in various variants of strain crossing, infected and noninfected, with bacteria has been carried out. The results have shown the absence of the influence of infection with Wolbachia on the frequency of crossing-over in the studied region of the X chromosome of D. melanogaster.     

Fine structure of early human embryos frozen with 1,2 propanediol

Previous studies by a French group (Fertil Steril 44:645–651, 1985) have shown that two-to eight-cell human embryos can survive slow freeze-thawing with propanediol in a biological freezer. These embryos were assessed for morphological appearance by phase-contrast microscopy. We assessed the structure of 25 frozen-thawed one- to 12-cell embryos, obtained from our in vitro fertilization (IVF) and GIFT programmes, by phase-contrast and electron microscopy, using the same method of cryopreservation. One-fourth of the embryos examined had all cells intact, and more than one-half the embryos had over 50% of their cells well preserved. Some of these embryos had unequal blastomeres and cytoplasmic fragments. Ultrastructural assessment revealed good preservation of fine structure in the intact blastomeres of all embryos and maintenance of cell-to-cell contacts. Most cytoplasmic organelles, cell membranes, and nuclei were well preserved compared to nonfrozen controls. The cells that were cryoinjured showed varying degrees of disorganization of the cell membrane, cytosol, and cellular membranes, including swelling and disruption of the nuclear envelope. Disruption of the zona was somewhat rare. Small cytoplasmic fragments were less prone to cryoinjury than blastomeres. The use of propanediol for embryo cryopreservation seems to be feasible; frozen embryos with more than 50% cells intact have produced 10 pregnancies after embryo transfer (Fertil Steril 46:268–272, 1986). Replacement of 17 frozen embryos in seven patients has resulted in a twin pregnancy in Singapore. However, the effects of freezing on the mitotic spindles of embryonic cells need to be investigated further.     

Evidence for the existence of three or more slow phases in the refolding of ribonuclease A and some characteristics of the phases

The slow refolding kinetics of RNase A have been analyzed, by using a nonlinear least-squares program for deconvoluting the kinetic phases and applying statistical tests for quality of fit. It is found that a minimum of three slow phases are required to fit the kinetic data properly, and this is true whether the method of detection is absorbance of fluorescence. Since the number of phases and the relaxation times for each phase are independent of the method of detection, it is concluded that the same three rate-limiting processes are seen by absorbance and fluorescence. These phases correspond to the XY, CT, and ct phases described in our earlier studies. The fact that fluorescence-detected kinetics are somewhat slower than absorbance-detected kinetics is a trivial effect due not to differences in relaxation times but to the fact that the amplitude of the CT phase is enhanced in fluorescence measurements, at the expense of the faster XY phase, because of intrinsic fluorescence changes associated with the isomerization of proline-93. By use of a new double-jump technique [Schmid, F.X., Grafl, R., Wrba, A., & Beintema, J.J. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 872], it is shown that proline-93 isomerizes as the rate-limiting step in only one of the three phases, the CT phase, and that this phase involves only 25-30% of the RNase molecules. There is still no indication as to the molecular events that occur in the large, ammonium sulfate dependent XY phase, which is the pathway for formation of the nativelike intermediate.     

Determination of surface immunoglobulin density on frozen-thawed mononuclear cells analyzed by the fluorescence-activated cell sorter

Recent data have demonstrated that differences in sIg density on B lymphocytes distinguish functionally distinct subpopulations of these cells. Other reports suggest that cyropreservation may change the frequency of sIg-bearing lymphocytes. To determine if cryopreservation alters either the frequency of sIg cells or the distribution of sIg density, PBM from normals and patients with CLL and LCL were analyzed using the FACS. Aliquots of Ficoll-Hypaque-separated PBM were controlled-rate frozen (1 °C/min) in 7.5% Me₂SO in RPMI 1640 and thawed in a 37 °C water bath on the same day. Fresh and frozen-thawed PBM aliquots were labeled with fluorescein conjugates of F(ab′) fragments of affinity chromatography-purified anti-Fab or class-specific anti-μ, anti-δ, anti-γ, or anti-α. Histograms of relative cell fluorescence, reflecting sIg density, were prepared for each aliquot with the FACS. The frequency of sIg-bearing PBM labeled with each reagent was not significantly altered by freezing. Likewise, FACS profiles demonstrated that the distribution of sIg density on normal and CLL PBM was unchanged after freezing. However, the fluorescence peak produced by frozen-thawed unlabeled cells was occasionally slightly broader than that of fresh cells, suggesting increased autofluorescence induced by freezing. These data indicate that frozen cell preparations may be utilized for the study of B-lymphocyte subsets as determined by sIg density.     

Histopathological survey of male gonads offish from petroleum production and control sites in the Gulf of Mexico

Testes, collected from 11 species of demersal and platform associated pelagic fishes, were examined microscopically for petroleum induced lesions. The fish were taken from 19 oil and gas production platforms and four control sites from the north-central Gulf of Mexico, during two periods, spring and late summer. The status of the spermatogenic cycle at the time specimens were collected correlated well with the known spawning times for the respective species of fish with one exception. Histopathological evaluation revealed acidophilic granular cells, chromatophores, degeneration and focal leucocytic aggregations as the most prominent and abundant conditions in testes, with encapsulated cysts, protozoa and helminths being observed only rarely. No evidence of adverse effects on gonadal morphology was found.     

Isolation and Antifungal Susceptibility of <Emphasis Type="Italic">Exophiala dermatitidis</Emphasis> Isolates from Human Stool Samples in Nigeria

We screened a total of 460 stool samples from humans with and without underlying disease for the black yeast and neurotrope, Exophiala dermatitidis using conventional and molecular identification procedures. Sixteen (3.5%) samples were positive. Twelve out of the sixteen positive samples where the fungus was recovered were from individuals who had diarrhoea at the moment of isolation. Two asymptomatic positive cases were within the age bracket of 21–30. Susceptibility testing of the strains using the CLSI M38 protocol suggests that almost all the strains were susceptible to amphotericin B, 5 fluorocytosine, itraconazole, fluconazole and voriconazole. Considering the health risk currently posed by this organism in Asia, especially among healthy younger subjects of the population and the scarcity of data on this fungus in Africa in general and Nigeria in particular, some recommendations were suggested.