Thermodynamic analysis of precisely measured oxygen equilibria of tench (Tinca tinca) hemoglobin and their dependence on ATP and protons

Summary Precise oxygen equilibria including extreme, high and low saturation values were determined for hemoglobin (Hb) from the freshwater teleostTinca tinca at three temperatures, each at two pH levels and in the presence and absence of the erythrocytic cofactor ATP, at twofold molar excess over Hb.Analysis of the data in terms of Adair's successive oxygenation theory shows that in the absence of ATP, each of the four oxygenation steps are exothermic, but that net heat release decreases as pH falls from 8.2 to 7.4. ATP greatly depresses the temperature sensitivity of oxygenation particularly at physiological erythrocytic pH, where endothermic cofactor dissociation finds expression in a reverse temperature sensitivity for binding of the 3^rd oxygen molecule to the tetrameric Hb.Enthalpy (H _i) and entropy (S _i) changes of oxygenation vary with oxygenation step, i, as well as with pH and ATP addition, but the variations of H _i are similar to those of S _i reflecting enthalpy-entropy compensation.The data show that the cooperative effects in tench Hb can be dominated either by entropic or enthalpic contributions, depending on the experimental condition and the oxygenation step.     

Effects of membrane physical parameters on hematoporphyrin-derivative binding to liposomes: A spectroscopic study

Summary Physical parameters of membrane bilayers were studied for their effect on the binding of hematoporphyrin derivative (Hpd), which is used as a sensitizer in photodynamic therapy of cancerous tissues. The purpose of this study was to clarify which parameters were relevant, under physiological conditions, to the selectivity of Hpd binding to cancer cells. Fluorescence spectroscopy was used to measure the relative partitioning of the dye between the lipid and aqueous media. Increasing the microviscosity of the liposomes' membranes by various bilayer additives results in a strong reduction of Hpd binding, to an extent independent of the specific additive. The effect of temperature near the physiological value as well as the effect of cross membrane potential are small. Surface potential does not affect the binding constant, indicating that the binding species does not carry a net electric charge.     

Stereoselective formation of a 2′(3′)-aminoacyl ester of a nucleotide

Summary Reaction ofDl-serine and adenosine-5-phosphorimidazolide in the presence of adenosine-5-(O-methylphosphate) and imidazole resulted in the stereoselective synthesis of the aminoacyl nucleotide ester 2(3)-O-seryl-adenosine-5-(O-methylphosphate). The enantiomeric excess ofd-serine incorporated into 2(3)-O-seryl-adenosine-5-(O-methylphosphate) was about 9%. Adenylyl-(5N)-serine and an unknown product also incorporated an excess ofd-serine; however, serylserine showed an excess ofl-serine. The relationship of these results to the origin of the biological pairing ofl-amino acids and nucleotides containingd-ribose is discussed.     

Decisive role of intermediate filament typing of tumor cells in the differential diagnosis of difficult fine needle aspirates

Thirty-six diagnostically difficult fine needle aspirates from enlarged lymph nodes and malignant soft tissue tumors, containing tumor cells with scanty or no obvious light microscopic features indicative of their differentiation, were assessed by a panel of six cytopathologists. Their diagnoses were recorded and then compared with the definitive diagnosis established by combining the cytologic findings with the results of intermediate filament typing of tumor cells in the smears using monoclonal antibodies specific for each filament type. The results show that use of these antibodies can markedly improve the accuracy of the cytologic diagnosis of tumor type as well as revise or prevent erroneous cytologic diagnoses in difficult cases. This pertains especially to the differential diagnoses of carcinoma versus malignant lymphoma, carcinoma versus malignant melanoma, carcinoma versus sarcoma and squamous carcinoma versus carcinoma of simple epithelia. Intermediate filament typing of tumor cells in aspirates as an objective histogenetic criterium makes the differential diagnosis of the difficult aspirates much more reliable and reproducible, provided that appropriate questions are asked, monoclonal antibodies with well-defined specificities are used and the antigenicity of the intermediate filaments in smears is preserved.     

Neuroendocrine (Merkel-cell) carcinoma of the skin. Cytology, intermediate filament typing and ultrastructure of tumor cells in fine needle aspirates

The light and transmission electron microscopic findings and the intermediate filament typing of tumor cells from fine needle aspirates of primary, recurrent and metastatic neuroendocrine (Merkel-cell) carcinoma of the skin are described. The tumor cells in the smears coexpressed keratins and neurofilaments and were characterized by "intermediate filament buttons," i.e., buttonlike fragments of cytoplasm of tumor cells, which could be observed either by staining with intermediate filament-specific antibodies using immunofluorescence or by their appearance in hematoxylin-and-eosin-stained smears. These features may help in the differential diagnosis of fine needle aspirates of neuroendocrine carcinomas of the skin.     

A 45,X male with Y-specific DNA translocated onto chromosome 15.

A 20-year-old male patient with chromosomal constitution 45,X, testes and normal external genitalia was examined. Neither mosaicism nor a structurally aberrant Y chromosome was observed when routine cytogenetic analysis was performed on both lymphocytes and skin fibroblasts. Y chromosome-specific single-copy and repeated DNA sequences were detected in the patient's genome by means of 11 different recombinant-DNA probes of known regional assignment on the human Y chromosome. Data indicated that the short arm, the centromere, and part of the long-arm euchromatin of the Y chromosome have been retained and that the patient lacks deletion intervals 6 and 7 of Yq. High-resolution analysis of prometaphase chromosomes revealed additional euchromatic material on the short arm of one of the patient's chromosomes 15. After in situ hybridization with the Y chromosome-specific probe pDP105, a significant grain accumulation was observed distal to 15p11.2, suggesting a Y/15 chromosomal translocation. We conclude that some 45,X males originate from Y-chromosome/autosome translocations following a break in the proximal long arm of the Y chromosome.     

Evolution of the secondary haustoria to a primary haustorium in the parasiticScrophulariaceae/Orobanchaceae

In the parasiticScrophulariaceae andOrobanchaceae, two types of contact organs exist: secondary and primary haustoria. Secondary haustoria are lateral organs, developing in large numbers and only when the seedling is fully established. In contrast, a primary haustorium represents the first developmental stage of the seedling itself. In the root system of the parasiticLesquereuxia syriaca (=Siphonostegia syriaca) there are only secondary haustoria, but a few of them apparently develop in a terminal position. This is achieved by transferring the haustorial initiation region closer to the root apex. One can interpret this as a transformation of the apical meristem into a meristematic haustorial tissue. On the condition that an extreme shortening (abbrevation) of the primary root could happen, we discuss the transformation of the terminal secondary into a primary haustorium.     

Cloning and characterization of keratin D,a murine endodermal cytoskeletal protein induced during in vitro differentiation of F9 teratocarcinoma cells

Summary We have identified a cDNA coding for the murine keratin D from a collection of clones representing F9 teratocarcinoma stem cell mRNA sequences. These sequences are synthesized specifically after the addition of retinoic acid and cAMP to the culture medium. The clone is 1,382 nucleotides long and contains the entire information for the active polypeptide, the complete 3 end and most, if not all, of the 5 non-coding region. The mRNA is found in hepatocytes, in PYS-2 cells (an endodermal cell line) and in differentiated (retinoic-acid-treated) F9 cells, but not in untreated F9 cells. The length of the mRNA is 1.4 kb, as estimated by Northern blot hybridization. Southern hybridization performed under very stringent conditions detects a single fragment hybridizing strongly with the cloned cDNA, suggesting that the mouse genome contains only one or very few copies of this gene. We present the first complete sequence of a keratin expressed in simple epithelia, i.e. keratin D, and discuss its structural features.     

Functional differences between small and large luteal cells of the late-pregnant vs. nonpregnant cow

This paper describes an in vitro model for the study of two types of steroidogenic luteal cells from cows in different physiological states. Two different populations of enzymatically dispersed bovine luteal cells were separated on the basis of size in a Cel-Sep Sedimentation Chamber. The separated small (12.5-23 micron in diameter) and large (greater than 23 micron in diameter) luteal cells of late-pregnant cows (Days 190-280) contained the distinct morphological characteristics previously defined for these two populations of cells. Cells were evaluated for progesterone (P4) production during a 3-h incubation with and without bovine luteinizing hormone (bLH, 10 ng/ml). Both small and large luteal cells from the late-pregnant cow were found to contain equal levels of P4 at Time 0 and increased but equal levels of P4 after a 3-h incubation. Neither cell type showed an increase in P4 production in response to the addition of bLH (p greater than 0.05). Since these results differed from earlier reports for luteal cells of the nonpregnant cow, small and large luteal cells of the mid-cycle (Day 14) were incubated, and the levels of P4 production were compared with P4 levels from the late pregnant cow. In agreement with previous reports for nonpregnant cows, progesterone content at Time 0 was 7-fold higher in large cells than in small cells (p less than 0.05), and after 3 h of incubation, 13-fold higher (p less than 0.05). Although the small cells responded to the presence of bLH in the incubation medium with a 4-fold increase in P4 production, this increase was not significant (p greater than 0.05). The large cell did not respond to bLH. However, the large cell type continued to contain and produce more P4 than did the small cells treated with bLH. This study indicates that both the small and large luteal cells of late-pregnancy are able to produce P4. However, the large luteal cell of the estrous cycle produces greater quantities of P4 than does the small luteal cell or the large luteal cell of late pregnancy.