Addition of carbohydrate side chains at novel sites on influenza virus hemagglutinin can modulate the folding, transport, and activity of the molecule

We have constructed and expressed a series of mutant influenza virus hemagglutinins, each containing a new consensus site for glycosylation in addition to the seven sites found on the wild-type protein. Oligosaccharide side chains were added with high efficiency at four of the five novel sites, located on areas of the protein's surface that are not normally shielded by carbohydrate. Investigations of the structure, intracellular transport, and biological activities of the mutant hemagglutinin molecules indicated that (a) supernumerary carbohydrate side chains can be used to shield or disrupt functional epitopes on the surface of hemagglutinin, and (b) the presence of an additional oligosaccharide may cause temperature-dependent defects in the transport of the glycoprotein. We discuss the addition of supernumerary oligosaccharides as a general tool for shielding chosen areas of the surface of proteins that enter or traverse the secretory pathway.

Genetics or environment? Type A behavior and cardiovascular risk factors in twin children

The heritability of Type A behavior and other cardiovascular risk factors was investigated in twin school-age children. The purpose was to differentiate those risk factors that have the potential to respond to environmental and life-style changes. The sample consisted of 71 monozygotic and 34 same-sex, dizygotic twin pairs 6 to 11 years old residing in the Philadelphia metropolitan area. Systolic and diastolic blood pressure, triceps skinfold thickness, body mass, and fasting blood specimens for lipid profiles were collected during home visits. Teachers rated the children's Type A behavior and two of its subcomponents, impatience-aggression and competitive achievement-striving, using the Matthews Youth Test for Health. Statistically significant heritability estimates were found for Type A behavior and its subcomponents, triglycerides, systolic blood pressure, and body mass. Nevertheless, there was substantial environmental influence on these risk factors. The greatest environmental influence was observed for HDL-cholesterol, LDL-cholesterol, apolipoprotein-B and diastolic blood pressure.

Mouse strain differences in subset distribution and T cell antigen receptor expression among CD4-CD8- thymocytes

'Double negative' (CD4-CD8-) thymocytes from adult mice of different inbred strains were examined for surface expression of CD3 and of various forms of the T cell antigen receptor (TcR), as well as for the levels of subpopulations defined by the surface markers HSA ('heat stable antigen', recognized by M1/69, J11d and B2A2), CD5 (Ly 1) and Thy 1. Marked variations were found in the level of the double negative subsets which were surface TcR+, or which were HSA-CD5+; these generally varied together since most CD4-CD8-HSA-CD5+ thymocytes were TCR+. The level of the CD3-TCR complex on the surface of those double negative thymocytes which were TcR+ was as high as on mature T cells in some strains (CBA/Ca), but was much lower in other strains (C57BL/6J). In most mouse strains the CD4-CD8-HSA-CD5+ thymocytes expressed predominantly the alpha beta form of the TcR, with an exceptionally high (70%) usage of V beta 8 gene products. In strains which lacked V beta 8 expressing T cells due to a deletion of the V beta 8 gene region, reduced levels of alpha beta TcR+ cells were found within the CD4-CD8- thymocytes; the HSA-CD5+ subset was then only present at low levels (as in SJL/J and C57BR mice) or was present at a high level but expressed predominantly gamma delta TcR (as in SWR mice). The results suggest that the accumulation of CD4-CD8-TcR+ HSA-CD5+ thymocytes is a selective event, and that their developmental pathway is off the mainstream of T cell maturation in the thymus.

Rigid sigmoidoscopy: an evaluation of three parameters regarding diagnostic accuracy

Rigid sigmoidoscopy is the method employed for examining the rectum and sigmoid colon in most general surgical clinics. Commonly, this is performed without any prior preparation of the bowel and with the patient in the left lateral (Sims') position. This study was designed to assess three factors relating to this method: preparation of the bowel; position of the patient; and the experience of the operator. The study shows that diagnostic accuracy without preparation is adequate in only 50 per cent of cases but, by employing a preliminary disposable (Fletcher's) enema, this can be improved to 80 per cent. Employing the knee-elbow position gave only slight advantage over the usual Sims' position and operator experience did not improve diagnostic accuracy once familiarity with the use of the sigmoidoscope had been achieved. The study underlines the importance of preparation as an essential prelude to sigmoidoscopy.

MR imaging of mediastinal pseudocyst

Magnetic resonance imaging of a mediastinal pseudocyst clearly demonstrated the entirely intrathoracic location of the pseudocyst.

Potential placenta previa: definition, frequency, and significance

Sixty-three (5%) of 1239 women studied by sonography during the second trimester of their pregnancies had a diagnosis of placenta previa. Follow-up was available for 51 of the 63 patients; in three of these, the original diagnosis was complete placenta previa, and in the other 48, the first diagnosis was partial or marginal placenta previa. At term, placenta previa was seen in only four patients for an overall frequency of 0.3% (4/1227). In all three of the patients with complete placenta previa, the condition persisted from the second trimester to term; previa persisted in only one of 48 patients with marginal/partial previa. Because of the infrequent persistence of marginal or partial placenta previa to term, we recommend using the term "potential placenta previa" in the second trimester, with follow-up sonography indicated only for vaginal bleeding.

Effects of leukotriene B4 inhalation. Airway sensitization and lung granulocyte infiltration in the guinea pig

Male Hartley guinea pigs were exposed by inhalation to leukotriene B4 (LTB4) and challenged 5 min or 4 h later with bronchoconstrictive aerosols of histamine or the divalent cationic ionophore A23187. Pulmonary gas trapping measured in excised lungs indicated the severity of post-challenge airway obstruction. Airway granulocyte infiltration was scored by an observer who was unaware of animal assignments. Treatment with LTB4 produced a marked influx of eosinophils and neutrophils into tracheal and bronchial airways. Granulocyte scores for LTB4-treated groups were 1.9 to 3.3 times higher than those for vehicle-treated groups at 5 min after exposure and 3.3 to 10.7 times higher at 4 h after exposure. Leukotriene B4 itself did not produce hyperinflation. However, histamine-induced gas trapping was increased 5 min after LTB4 exposure. Histamine responsiveness was unaffected 4 h after LTB4 treatment. In contrast, A23187-induced gas trapping was unaffected at 5 min, but diminished at 4 h after LTB4. Nonchemotactic stereoisomers of LTB4 did not produce granulocyte influx, but did produce altered airway responses similar to those seen for LTB4. We conclude that inhaled LTB4 produces airway granulocyte infiltration in the guinea pig and alterations in airway responsiveness that vary with the challenge stimulus and time after exposure. Alterations in airway responses may result from granulocyte-independent effects of LTB4 and its stereoisomers.

Alterations in liver blood flow and reticuloendothelial function in progressive cirrhosis in the rat

Cirrhosis of the liver was induced in rats by twice weekly inhalation of carbon tetrachloride in conjunction with sodium phenobarbitone administration. At sequential time intervals during induction, liver blood flow and extraction efficiency of colloid were assessed in order to elucidate changes in these parameters which occur with cirrhosis. Liver samples were also taken for histologic examination and graded for extent of disease. Initially there was a fall in extraction efficiency (and thus reticuloendothelial function), associated with early histologic change. Subsequently extraction efficiency recovered, as regeneration was observed on histologic specimens. From 4 wk and onward, blood flow gradually fell, as did extraction efficiency. These changes were associated with increasing severity of disease as demonstrated by histologic sections.

Social support and arterial pressure in a central Mexican community

Research on the relationship of social support and arterial blood pressure was conducted in a town in central Mexico. A culturally appropriate measure of social support was developed assessing perceived support from relatives, friends, neighbors, and compadres (ritual kin). The effects of perceived support from these four sources were compared to the effects of the amount of reported social contacts. For males, more support from all four sources was related to lower arterial pressure, whereas amount of social contact was related to higher diastolic blood pressure; support from compadres had the largest inverse correlation with blood pressure. For females the pattern of correlations was dependent on age: support from relatives and friends was related to higher blood pressure for younger females, whereas support from relatives was related to lower blood pressure for older females. This pattern of relationships is consistent with the place of women in the social structure of this Mexican community, and these results point to the need to conceptualize and measure social support in culturally appropriate ways.

Inflammatory infiltrates in human coronary atherosclerosis

The nature and density of coronary arterial inflammatory infiltrates were studied in autopsy material from 53 patients with no clinical or pathological evidence of ischaemic heart disease and from 22 acute cardiac deaths. Adventitial aggregates of inflammatory cells were present in 46% of cases and were slightly more frequent in arteries from patients with ischaemic heart disease. The majority of these cells were lymphocytes and immunohistochemical studies with monoclonal antibodies indicated that both B and T cells were present. Staining with polyclonal antibodies to macrophage antigens confirmed that some adventitial cells were macrophages. The reactions of foam cells within the atheromatous plaques were extremely variable but some foam cells gave unequivocably positive reactions with macrophage antibodies. There was a good overall correlation between the numbers of intimal and medial foam cells and the density of the adventitial lymphocytic infiltrates. It is suggested that these infiltrates develop as a secondary feature of atheromatous lesions and are unlikely to play a major role in their initiation or in the development of complications.

Radioiodinated ganglioside GM1: a potential tool for the investigation of ganglioside function in vivo

Ganglioside GM1 was labeled with 125I either directly or after conjugation to tyramine. Direct iodination of the sphingosine chain resulted in a compound which dehalogenated rapidly both in vitro and in vivo. The binding of the 125I[GM1-tyramine] conjugate to neuronal membranes in vitro was similar to that reported for 3H-GM1. The biodistribution of 125I activity after intravenous injection of 0.5 uM and 5 uM 125I[GM1-tyramine] in mice was also similar to that reported for 3H-GM1. This radioiodinated GM1 derivative might be useful for the study of ganglioside GM1 function in vivo.

Efficacy of ECT: a meta-analysis

The authors analyzed several rigorously controlled studies that compared the efficacy of ECT with that of simulated ECT, placebo, and antidepressants. The data from these studies were combined statistically (with the Mantel-Haenszel method for the combination of fourfold tables), showing ECT's clear superiority over all these other forms of treatment for severe depression. The authors similarly analyzed the data from several studies comparing the efficacy of unilateral nondominant ECT with that of bilateral ECT and found no significant difference in their efficacy.

A comparison of serum albumin, age and the sheffield prognostic index in the prediction of surgical complications

The ability of the Sheffield prognostic index (S.P.I) to predict postoperative complications and death in patients undergoing gastrointestinal surgery has been compared with that of serum albumin alone, and with age. Both the S.P.I. and age were better at predicting complications than serum albumin. Serum albumin was the best predictor of death.

Clinical comparison of Michel and Proximate clips used for abdominal wound closure

For many years Michel clips (Down Surgical, Mississauga, Ont.) have been used to close wounds and results have been good, but several newer clips are now available (e.g., Proximate; Ethicon Sutures Ltd.), which are said to be easier to use and produce a better scar. However, they are much more expensive. The authors carried out a prospective controlled study in which 30 patients with abdominal incisions had half of the skin incision closed with Michel clips and the other half with Proximate clips. They assessed ease of insertion and removal, and appearance of the wound immediately after removal and 2 months later. Ethicon Proximate clips were, in general, slightly easier to insert, less uncomfortable to remove in 8 of the 30 patients and gave a better immediate cosmetic result in 9 patients. However, there was no difference in the appearance of the wound 2 months later. The authors do not consider that Ethicon Proximate clips offer an advantage over the much less expensive Michel clips.

Gastric sarcoidosis

Two cases of gastric sarcoidosis are reported. Both patients presented with a history suggestive of peptic ulceration and the diagnosis of sarcoidosis was made after operation.

Leukotrienes (LTB4 and LTD4): in vitro effects on human lymphocyte proliferation and transformation

The effects of leukotrienes LTD4 and LTB4 on cell proliferation were assessed in a human in vitro lymphocyte transformation assay in the presence of optimal concentrations of PHA, Con A and PWM. Leukotriene D4 and LTB4 (10(-6) to 10(-11) M) did not alter the basal or mitogen-stimulated response. We therefore conclude that these two agents do not play a role in the modulation of human lymphocyte blastogenesis.