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Biomedical subjects

A Christensen

Publications and source records attributed to A Christensen.

At least 19 recordsLinked to original sources
PubMed1995

Very low density lipoprotein receptor binds and mediates endocytosis of urokinase-type plasminogen activator-type-1 plasminogen activator inhibitor complex.

Very low density lipoprotein receptor (VLDL-R) was found to be expressed in bovine mammary gland and the human breast carcinoma cell line MCF-7 as an M(r) 105,000 variant, and in Chinese hamster ovary (CHO) cells transfected with human VLDL-R cDNA as an M(r) 130,000 variant. The receptor was purified by ligand affinity chromatography with immobilized M(r) 40,000 receptor-associated protein (RAP). The purified receptor was found to bind urokinase-type plasminogen activator-type-1 plasminogen activator inhibitor complex (u-PA.PAI-1), while there was no or very weak binding of active site blocked u-PA (DFP-u-PA), PAI-1 or u-PA-type-2 plasminogen activator inhibitor complex. The binding of u-PA.PAI-1 was blocked by RAP. The transfected CHO cells had an efficient, RAP-sensitive endocytosis of u-PA.PAI-1, severalfold higher than non-transfected parental CHO cells. u-PA.PAI-1 endocytosis was partially inhibited by DFP-u-PA, which blocks binding of the complex to the u-PA receptor. RAP and DFP-u-PA sensitive u-PA.PAI-1 endocytosis was also observed in MCF-7 cells, which were without detectable levels of other RAP-binding endocytosis receptors. These results show that VLDL-R represents a novel endocytosis mechanism for u-PA receptor-bound u-PA.PAI-1.

Amino Acid Sequence↗
PubMed1995

The longitudinal impact of demand and withdrawal during marital conflict.

Forty-eight couples completed a measure of relationship satisfaction and participated in 2 video-taped problem-solving interactions, 1 focused on an issue identified by the woman and 1 focused on an issue identified by the man. Thirty-six men and 36 women completed the satisfaction measure again 2.5 years later. Demandingness, and to a lesser extent withdrawal, during the interactions showed many significant associations with both Time 1 and Time 2 satisfaction. The relationship of demandingness and withdrawal to change in satisfaction was also examined using both change scores and partial correlations. Withdrawal by men and woman demand-man withdraw during discussions of issues identified by the women reliably predicted change (decline) in wives' relationship satisfaction.

Conflict, Psychological↗
PubMed1991

Communication, conflict, and psychological distance in nondistressed, clinic, and divorcing couples.

This study compared communication patterns and conflicts over psychological distance in 25 nondistressed couples, 15 clinic couples, and 22 divorcing couples. Data consisted of questionnaire reports completed independently by husbands and wives. The two distressed groups, compared with nondistressed couples, had less mutual constructive communication, more avoidance of communication, more demand/withdraw communication, and more conflict over psychological distance in their relationships. In addition, the divorcing group had less mutual constructive communication than the clinic group and evidenced a trend for more conflict over psychological distance than the clinic group. Consistent with past research, wife demand/husband withdraw communication was more likely across all groups than husband demand/wife withdraw communication. Results are discussed in terms of skills deficits and incompatability models of marital discord.

Adult↗
PubMed1990

Clinical evidence supporting the radical scavenger mechanism of 5-aminosalicylic acid.

5-Aminosalicylic acid, the therapeutically active metabolite of sulfasalazine, was exposed to oxygen-derived free radicals produced by the Fenton reaction in vitro, and several metabolites were detected and characterized by high performance liquid chromatography and ultraviolet spectrophotometry. The majority of these metabolites were present in methanolic extracts of feces samples from sulfasalazine-treated patients with inflammatory bowel disease but not in rheumatoid arthritis patients with normal bowel function. The presence of these metabolites, which have not been demonstrated in vivo before, provides evidence of an interaction between 5-aminosalicylic acid and oxygen-derived free radicals in sulfasalazine-treated patients with inflammatory bowel disease. Since the concentration of lipid peroxides, which is dependent on the release of oxygen-derived free radicals, was significantly increased in pretreatment rectal biopsies of the patients, and further was normalized concomitantly with a significant improvement in disease activity over the 5-wk treatment period, an important role of the radical scavenger mechanism of 5-aminosalicylic acid in sulfasalazine therapy of chronic inflammatory bowel disease is strongly suggested.

Adult↗
PubMed1990

Gender and social structure in the demand/withdraw pattern of marital conflict.

This study examined the effects of gender and social structure on the demand/withdraw pattern of marital conflict. In this pattern, the demander, usually the woman, pressures the other through emotional requests, criticism, and complaints, and the withdrawer, usually the man, retreats through defensiveness and passive inaction. In this study, 31 couples were assessed in 2 conflict situations: 1 in which husband wanted a change in wife and 1 in which wife wanted a change in husband. Data from husbands, wives, and observers consistently revealed a significant main effect of gender (wife-demand/husband-withdraw interaction was more likely than husband-demand/wife-withdraw interaction) and a significant interaction of gender and conflict structure (wife-demand/husband-withdraw interaction was more likely than the reverse only when discussing a change the wife wanted). Separate analyses of demand and withdraw behaviors indicated that both husband and wife were more likely to be demanding when discussing a change they wanted and more likely to be withdrawing when discussing a change their partner wanted. However, men were overall more withdrawn than women, but women were not overall more demanding than men.

Adult↗
PubMed1990

Pharmacokinetics and metabolism of a leukotriene D4/E4-antagonist (2-[3'-(2"-quinolylmethoxy)phenylamino]benzoic acid) in rat, dog,guinea pig and man.

1. The absorption, distribution, metabolism and excretion of 2-[3'-(2"-quinolyl-methoxy)phenylamino]benzoic acid (QMPB), a novel leukotriene D4/E4 antagonist, were investigated in rat, dog, guinea pig and man. 2. The oral absorption of the potassium salt of QMPB was rapid and almost complete (90%) in rats, and about 50% in dogs. In man, high oral bioavailability was indicated. Absorption in dogs of the zwitterion form was only 7%. 3. The distribution of 3H-QMPB was examined in rats and guinea pigs. Whole-body autoradiography in rats showed that radioactivity was concentrated predominantly in the liver, bile and intestinal lumen, after both oral and i.v. administration. 4. A major metabolite was identified as the O-ester beta-glucuronide of QMPB. 5. Renal excretion in rat, dog and man was very low. In rat, almost complete biliary excretion of QMPB as the glucuronide conjugate was demonstrated. 6. Pronounced enterohepatic circulation of QMPB was demonstrated in rats, and the plasma concentration curves and the negligible renal excretion in dog and man also indicate enterohepatic circulation in these species.

Adult↗
PubMed1989

Gastrocolic fistula resulting from chronic pancreatitis.

Gastrocolic fistulas are rare, and are usually seen as complications of peptic ulcer or malignancy of the stomach and large intestine. We have described a case resulting from chronic relapsing pancreatitis. The patient was successfully treated with excision of the fistula and closure of the gastric and colonic wall.

Chronic Disease↗
PubMed1988

Perforated gastric ulcer.

A retrospective study is presented of 297 patients operated upon for perforated benign gastric ulcer in Denmark from 1975 to 1984. Male:female ratio was 0.9:1, mean age 64.2 years. The numbers of gastric and prepyloric perforations were almost equal (156:141), but gastric perforations were more frequent in elderly women and prepyloric perforations in younger men. Simple closure was performed in 83 per cent of the patients, gastric resection in 14 per cent and simple closure and vagotomy in 3 per cent. The postoperative mortality rate was 21 per cent and was related to the high proportion of elderly patients with concurrent diseases and delayed treatment.

Adolescent↗
PubMed1988

Intestinal distension test, a method for evaluating intermittent visceral pain in the rabbit.

Behavioural response to intestinal distension was studied in 12 female New Zealand albino rabbits under various conditions. On increasing intraluminal pressures, the rabbits elicited uniform behavioural responses within discrete pressure ranges, notably a sudden pelvic withdrawal at 30-50 mmHg. The pressure provoking pelvic withdrawal was chosen as the test parameter and proved to be individually reproducible, irrespective of fasting/non-fasting or the time of day and with no signs of adaptation in six days consecutive measurements. Morphine modified the pressure response in a dose-dependent manner, whereas isotonic saline or pentobarbital had no effect. In conclusion, the intestinal distension test is reproducible and mimicks intermittent visceral pain in the rabbit. This allows for paired observations in small animal populations with a minimum of discomfort to the animals, which offers a major advantage when comparing with the existing visceral pain tests.

Animals↗
PubMed1988

Parental communication deviance: its relationship to parent, child, and family system variables.

Audiotape recordings of family interaction samples from 30 nondistressed and 32 multiproblem families were coded for communication deviance (CD). Maternal CD was found to be higher in families high on measures of "preschizophrenic" child behavior, externalizing or "acting out" offspring behavior, overall family distress, and maladaptive marital and family alliance structures. Paternal CD was found to be higher in families in which offspring were rated high on externalizing behaviors.

Acting Out↗
PubMed1988

Incidence of perforated and bleeding peptic ulcers before and after the introduction of H2-receptor antagonists.

The incidence of perforated and bleeding peptic ulcer requiring emergency surgery was studied in a defined population before and after the introduction of histamine H2-blockers. The incidence of these ulcer complications was unchanged from 1974 to 1984 with an incidence of ulcer perforation from 4 to 10/100,000 per year and of bleeding ulcer from 5 to 10/100,000, indicating that the H2-blockers have not changed the incidence of severe ulcer complications.

Adult↗
PubMed1988

Seasonal periodicity of perforated gastric ulcer.

The seasonal periodicity of perforated peptic ulcer of the stomach was analysed among 296 patients operated at seven departments of gastrointestinal surgery in Denmark between 1975 and 1984. Admissions were significantly higher in August and September with a tendency, although not significant, in March also. This pattern was unaffected by age and sex.

Adolescent↗
PubMed1988

Gastrocolic fistulas.

Sixteen patients were treated for gastrocolic fistula arising as a complication of peptic ulcer (11 cases), colonic perforation (2), gastric cancer (1), colonic cancer (1) or pancreatitis (1). The predominant symptoms were diarrhoea, weight loss and abdominal pain. Barium meal and barium enema were the most reliable means of diagnosis, and no fistula was gastroscopically demonstrable. A one-stage en bloc resection of the involved gastrocolic region was performed in eight cases. Other operations were simple excision (3), gastric resection with closure of the colonic wall (2) and colectomy with closure of the gastric wall (2). In one case cure was achieved with cimetidine, without surgical intervention. Four patients died postoperatively and two had recurrence of fistula.

Adult↗
PubMed1987

Structure and accessibility of domain I of Escherichia coli 23 S RNA in free RNA, in the L24-RNA complex and in 50 S subunits. Implications for ribosomal assembly.

Domain I of 23 S RNA of Escherichia coli was probed in renatured RNA, in the protein L24-RNA complex and in 50 S subunits with ribonucleases specific for single- and double-stranded regions and with chemical reagents specific for guanosines (N-1 and N-2), adenosines (N-1, N-7 and N-6), cytidines (N-3) and uridines (N-3). Reactive sites were detected by a reverse transcriptase procedure. The results support most new features of the latest version of the Santa Cruz/Urbana model of the secondary structure, which is based on evidence from sequence comparison. Most double-helical segments were reactive to cobra venom ribonuclease to some degree; the exceptions were the five "long-range" helices that are probably compactly folded within the structure. The data provide evidence for the occurrence of A(syn) X G(anti) pairings in internal loops and at the ends of some helices; they also support the existence of extensive higher-order structuring, especially within the interhelical regions, and are compatible with two of three tertiary interactions in the free RNA that were predicted from comparative sequence studies. Protein L24 is the only primary binding protein that associates with domain I and it strongly protects two sites against ribonuclease and chemical activity. Site A has the properties of a classic protein binding site and we conclude from four lines of evidence that it is the primary attachment site. Site B is rich in highly conserved, unpaired adenosine residues and lies in a potentially critical region of the structure adjoining a group of long-range helices; we infer that L24 binding here is related to the important role of L24 in initiating ribosomal assembly; the existence of both sites is supported, independently, by genetic experiments. L24-induced enhanced reactivities were detected throughout the domain and are consistent with a general "tuning" of the RNA structure. The RNA domain in the 50 S subunits is almost completely resistant to ribonucleases and only a few sites, mainly interhelical, are accessible to chemical reagents. The appearance of several newly reactive nucleotides in the subunit RNA and the enhancement of some others suggest that some minor conformational changes occur on assembly. Nevertheless, the minimal secondary structure of the renatured RNA appears to be retained. We draw the general conclusion that domain I is a highly structured domain that is important for initiating assembly and for the subsequent organization of the ribosome.

Binding Sites↗