Identification and oligosaccharide structure analysis of rhodopsin glycoforms containing galactose and sialic acid

The N-linked oligosaccharides of frog (Rana pipiens) rhodopsin were analysed by sequential exoglycosidase digestion and gel filtration chromatography, following reductive tritiation. In addition, selected tryptic glycopeptides obtained from frog retinal rod outer segment membranes were examined by electrospray mass spectrometry (ES-MS), fast atom bombardment mass spectrometry (FAB-MS), amino acid sequence and composition analysis, and carbohydrate composition analysis. The amino acid sequence data demonstrated that the glycopeptides were derived from rhodopsin and confirmed the presence of two N-glycosylation sites, at residues Asn2 and Asn15. The predominant glycan (approximately 60% of total) had the structure GlcNAc beta 1-2Man alpha 1-3(Man alpha 1-6) Man beta 1-4GlcNAc beta 1-4GlcNAc-(Asn), with the remaining structures containing 1-3 additional hexose residues, as reported previously for bovine rhodopsin. Unlike bovine rhodopsin, however, a sizable fraction of the total glycans of frog rhodopsin also contained sialic acid (NeuAc), with the sialylated oligosaccharides being present exclusively at the Asn2 site. FAB-MS analysis of oligosaccharides released from the Asn2 site gave, among other signals, an abundant quasimolecular ion corresponding to a glycan of composition NeuAc1Hex6HexNAc3 (where Hex is hexose and HexNAc is N-acetylhexosamine), consistent with a hybrid structure. The potential biological implications of these results are discussed in the context of rod outer segment membrane renewal.     

Risk factors for low birth weight and intrauterine growth retardation in Santiago, Chile

An epidemiologic case-control study to ascertain the determinants of low birthweight was carried out in Santiago, Chile, from January to December 1989. The cases were defined as livebirths < 2500 g. The controls were livebirths > or = 2500 g of birthweight. All cases and a random sample (1:1) of controls were selected among 8,254 singleton births occurring at the El Salvador Hospital in the Eastern area of Santiago. These deliveries represented 50% of institutional deliveries in the area. Home deliveries (2%) and private hospital deliveries were not included in the study. Information was obtained from hospital medical records by six trained medical students. Some information could not be obtained from the hospital medical records. Thus the second step in data collection was the tracking of all the selected subjects to their referring neighborhood health centers. For the analysis, the data were divided into 3 case (outcome) categories: 453 subjects were the total case group. From these, 153 were the IUGR case group and 300 were the LBW preterm case group. The general control group consisted of 605 normal birthweight infants. 565 were the IUGR control group and 40 were the preterm control group. A total of 25 risk factors showed a significant crude odds ratio for at least one of the groups. In the multivariate logistic regression analysis eight variables: No. of pregnancies, previous adverse outcomes, previous LBW, pregnancy maternal weight, No. of visits, month of first prenatal care visit, maternal smoking and intrahepatic cholestasis of pregnancy, were significantly associated with LBW after adjustment by confounding. Eight risk factors: IUGR in previous pregnancies, Previous adverse outcome, Maternal smoking, intrahepatic cholestasis, maternal pregnancy weight, maternal height, month first prenatal visit, No. of visit, were significant to IUGR. Only two variables: pregnancy weight, divorced mother, were significantly associated with low birth weight in the preterm group. The most relevant risk factors were included in stepwise logistic regression models carried out for the outcome LBW for the general group, term group and preterm group, in order to adjust by confounding. Adjusted odds ratios were then obtained. Prenatal care related factors and maternal adverse obstetric factors were at higher significance for LBW in the general and IUGR groups. Only nutritional factors were related to LBW in preterm group. Women who delivered a LBW or IUGR infant were more likely to have fewer pregnancies, a history of previous LBW, lower prepregnancy weight and lower gestational weight gain. ICP was associated with an elevated risk of LBW that was independent of gestational age.     

Role of ethics in modern health care: 2

The safety of estrogen use in breast cancer patients is discussed. Most reports indicate there is no risk.     

From fate to tragedy: the changing meanings of life, death, and AIDS

PURPOSE: Preliminary experience of radical retropubic prostatectomy using an endoscopic stapler is reported. METHODS: An endoscopic stapler was applied for ligation and division of the lateral prostatic ligaments and the deep dorsal vein complex during radical retropubic prostatectomy in 8 patients. RESULTS: Procedures with stapler were easily performed and almost always effective for hemostasis. Mean total blood loss was 663 ml, mean 575 ml of autologous blood was given. None of patients was transfused allogeneic blood. CONCLUSION: These results indicate that an endoscopic stapler may facilitate radical retropubic prostatectomy.     

Adult attachment and adult child-older parent relationships

Adult attachment status, concurrent and early relationships with parents, and depressive symptoms were assessed in 53 adults. Individuals with consistent reports of relationships--positive or negative--were most coherent in their narratives. Depressive symptoms were associated with negativity in both recalled and current relationships with parents, but were not correlated with coherence of narratives. Clinical implications of the findings are discussed.     

Directing phage selections towards specific epitopes

It is possible to direct selections from antibody repertoires displayed on filamentous phage towards unique epitopes on protein antigens by competing with related molecules. A phage display repertoire of human single chain Fvs (scFvs) was panned three times against foetal haemoglobin (HbF). The selection was dominated by one clone with a Kd of 10 nM but yielded at least 17 others, all of which bound HbF but crossreacted with adult haemoglobin (HbA). To direct selection towards HbF-specific epitopes, the repertoire was preincubated with HbA in solution before each panning. Crossreactive scFvs can form complexes with the soluble HbA and thereby be prevented from binding the immobilized HbF. Four clones with preferential binding to HbF emerged under these conditions. One of these (Hb-1), with a Kd of 6 microM, had exquisite specificity for HbF and could distinguish cells expressing HbF from those expressing HbA by immunocytochemistry and flow cytometry. This antibody has an affinity that is 600-fold lower than the dominant crossreactive clone, and so only emerged under conditions of 'competitive deselection'. Thus, competitive deselection is a viable means for directing selections towards useful epitopes. It permits a more effective 'search' of phage display repertoires and allows the emergence of lower affinity clones with useful specificities. These clones may be useful in themselves or may serve as leads for in vitro affinity maturation.     

Change in serum hyaluronan: a simple index of short-term drug-induced changes in hepatic sinusoidal perfusion

BACKGROUND: Hyaluronan is an endogenous polysaccharide whose clearance from the plasma is predominantly by liver sinusoidal cells and is sinusoidal flow dependent. This study was designed to determine if a change in serum hyaluronan might reliably reflect short-term drug-induced changes in sinusoidal perfusion. METHODS: Hemodynamic changes following an oral dose of ketanserin were compared with changes in serum hyaluronan levels in 12 patients with alcoholic liver disease and portal hypertension. Indices determined comprised heart rate, mean arterial pressure (MAP), cardiac output (CO), systemic vascular resistance, hepatic venous pressure gradient (HVPG), indocyanine green (ICG) clearance and extraction, and total hepatic blood flow. Measurements were made in a basal state 1 hour after ketanserin ingestion and expressed as a ratio of values post- to pre-ketanserin administration. RESULTS: Ketanserin had variable effects comprising both increases and decreases in all indices. On univariate and multivariate analysis, changes in serum hyaluronan concentration (1.05 +/- 0.13, mean +/- SD) significantly correlated with only one index: changes in ICG clearance (0.93 +/- 0.17, r = -0.65, P = 0.02). CONCLUSIONS: Changes in serum hyaluronan levels reflect short-term drug-induced changes in sinusoidal perfusion in patients with alcoholic liver disease and portal hypertension. Serial measurement of serum hyaluronan levels may offer a simple method of screening vasoactive drugs for their short-term effects on sinusoidal perfusion.     

The resistance of cowpea seeds to bruchid beetles is not related to levels of cysteine proteinase inhibitors

A cDNA encoding a cysteine proteinase inhibitor was isolated from a cDNA library prepared from developing seeds of an insect-resistant line of cowpea. The sequence of the encoded protein was homologous with those of other plant cysteine endoproteinase inhibitors, and with Type 2 cystatins from animals. Southern blot analyses indicated that small gene families were present in both resistant and susceptible lines of cowpea, while northern blot analyses showed similar levels of expression. It is concluded that the levels of expression of the inhibitor do not account for the differences in insect resistance of the two lines.     

Relationship between Magnetomechanical Damping Capacity and Vibration Modes

The mathematical expressions for magnetomechanical damping capacity are presented by applyingSmith-Birchak's model in torsion pendulum and cantilever beam.The peak value ψ_p is found to berelated to physical parameters and material constants in the form Kλ_s=αψ_pε_p.which can be used toestimate the magnetostrictive constant λ_s from the damping capacity-strain amplitude curve.A goodagreement of experimental data and theoretical prediction was observed in HIDAMETSCr15A13NiCu.