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Biomedical subjects

B Martin

Publications and source records attributed to B Martin.

At least 361 records · Page 20Linked to original sources
PubMed1985

A plasmid vector allowing positive selection of recombinant plasmids in Streptococcus pneumoniae.

A new plasmid, pSP2, was constructed as a cloning vector for use in Streptococcus pneumoniae. It allows direct selection of recombinant plasmids, even for DNA fragments not homologous to the S. pneumoniae chromosome, as based on the failure to maintain long inverted repeats (LIRs) hyphen-free in bacterial plasmids. Plasmid pSP2 contains a 1.4-kb BamHI fragment ("hyphen") flanked by 1.9-kb LIRs. The removal of the 1.4-kb BamHI fragment followed by ligation creates a plasmid containing a 1.9-kb insert-free LIR; plasmids with such non-hyphenated LIRs were not established when transferred into S. pneumoniae. Replacement of the original 1.4-kb insert by other restriction fragments restored plasmid viability. Investigation of plasmid transfer by transformation suggests that intrastrand synapsis between the LIRs could occur, thus facilitating plasmid establishment (a process we call self-facilitation). Such an intrastrand synapsis could also account for rare occurrences of insert-inversion noticed upon transfer as well as for the formation of palindrome-deleted derivatives at low frequency. Plasmid pSP2 carries two selectable genes, tet and ermC, and can be used for cloning of fragments produced by a variety of restriction enzymes (BamHI, Bg/II, Bc/I or Sau3A, and Sa/I or XhoI).

Chromosome Mapping↗
PubMed1985

Cloning of the hexA mismatch-repair gene of Streptococcus pneumoniae and identification of the product.

The hexA mismatch repair gene of Streptococcus pneumoniae has been cloned into multicopy plasmid vectors. The cloned hexA gene is expressed as judged from its ability to complement various chromosomal hexA- alleles. Its direction of transcription was defined and the functional limits were localized by original methods relying on homology-dependent integration of nonautonomous chimeric plasmids carrying chromosomal inserts into the chromosome. Comparison of the proteins encoded by recombinant plasmids and by restriction fragments allowed us to identify an Mr 94 000 protein as the probable product of the hexA gene.

Bacterial Proteins↗
PubMed1985

Gene mapping and leader polypeptide sequence of human glucocerebrosidase: implications for Gaucher disease.

Analysis of immunologic cross-reacting material in Chinese hamster-human somatic cell hybrids allowed assignment of the structural gene for glucocerebrosidase (glucosylceramidase; beta-D-glucosyl-N-acylsphingosine glucohydrolase, EC 3.2.1.45) to chromosome 1 bands q21-q32. In situ hybridization of a radiolabeled human glucocerebrosidase cDNA to high resolution human chromosomes demonstrated that a single locus encoding glucocerebrosidase is on 1q21, adjacent to a region of chromosome 1 (1qh) abundant in structural heteromorphisms. We also have identified a hydrophobic leader polypeptide encoded by this locus, permitting a more complete description of the biosynthesis of the enzyme. These results suggest that the type-specific protein polymorphisms in Gaucher disease result from mutations at this single locus, whose segregation might be followed by linkage to visible chromosomal heteromorphisms.

Animals↗
PubMed1985

Everyday problems and life change events: ongoing versus acute sources of stress.

Research on the relationship between life stress and illness has focused largely on stress caused by change. The present study examines a relatively neglected source of stress: everyday problems, defined as ongoing, often chronic situations, which are stressful for a substantial period of time. An inventory of everyday problems was developed, designed to minimize as much as possible potential confounds present in earlier work. It was administered to 281 undergraduate women along with a life events inventory, the Hopkins Symptom Checklist, and a social support scale, which measured family and nonfamily sources of support. Stepwise regression analyses indicated that everyday problems were more effective than life events in predicting psychological symptoms. Everyday problems were significant predictors of symptoms even after statistically controlling for life events, whereas life events had no predictive ability beyond that attributed to everyday problems. In addition, a significant interaction between everyday problems and life events was found. Multiple regression analyses also showed an interaction between everyday problems and nonfamily social support, as predicted by the buffering hypothesis. Within the methodological limitations of this study, these findings are interpreted as supporting the importance of everyday problems as a significant source of stress.

Adaptation, Psychological↗
PubMed1985

Factors associated with psychiatric morbidity in men--a general practice survey.

A survey of men aged from 20 to 59 years from a general practice list using the General Health Questionnaire and a questionnaire of social and domestic items yielded 1011 respondents. Several items were shown to be linked with psychological disturbance including ill health, ill health or psychiatric history in wife, poor relationship with wife, being unemployed, poor or divorced and lower social class. The results are compared with those of a similar sample of women.

Adult↗
PubMed1985

A double-blind out-patient trial of indalpine vs mianserin.

Indalpine 150 mg per day and mianserin 60 mg per day were compared in a double-blind study of 65 depressed out-patients: 52 patients completed the 4-week trial. At the end of four weeks there was no significant difference in antidepressant effect between the two drugs; but in the first two weeks, improvement in the mianserin-treated group was significantly greater than that in the indalpine group. The mianserin-treated group reported more side-effects of sedation (eg. drowsiness, clumsiness, heaviness of limbs etc.) and one patient on indalpine developed a mild leucopenia.

Adolescent↗
PubMed1985

Cholesterol in the plasma membrane of uterine epithelial cells: a freeze-fracture cytochemical study with digitonin.

Freeze-fracture cytochemistry with digitonin has been used to examine the cholesterol content of the plasma membrane of uterine epithelial cells during the early stages of pregnancy in the rat. Lesions caused by digitonin complexing with cholesterol were seen on both lateral and apical portions of the membrane but tight junctions and desmosomes were lesion-free. Compared with day 1 of pregnancy, lesions on the apical plasma membrane were much more extensive and some were of different morphology on day 6 - the day of blastocyst implantation. We consider mechanisms of lesion formation and interpret the results to indicate a higher content and perhaps a different organization of cholesterol in the apical plasma membrane on day 6 of pregnancy. We also suggest how this increase may occur.

Animals↗
PubMed1985

Intracellular human IL-1: a precursor for the secreted monokine.

An intracellular monocyte derived protein possessing interleukin 1 (IL-1) activity has been compared with the secreted from of IL-1. Our results indicated that this intracellular IL-1 had an apparent size greater than that of extracellular IL-1. Data are presented to show that a rabbit heterotypic antiserum prepared against epitopes on the secreted form of human IL-1 blocked the biologic activity of intracellular IL-1 in a dose dependent manner. Intracellular IL-1 had a mass of 30-40 kDa as determined by gel filtration using sephacryl-200 gel.

Cytoplasm↗
PubMed1984

Nonmedical costs to patients and their families associated with outpatient chemotherapy.

One hundred thirty-nine patients receiving outpatient chemotherapy kept diaries of nonmedical expenses resulting from their disease and its treatment. Diaries were kept for both treatment and nontreatment weeks. Results showed that the mean cost to patients and their families for treatment weeks was $72.81, and for nontreatment weeks it was $45.88. Approximately 45% of these costs were out-of-pocket expenses, and 55% were wages lost. Transportation and food were the largest out-of-pocket expenses. Patients living at greater distance from treatment had higher out-of-pocket costs, and younger patients reported more wages lost. Fourteen percent of the patients were estimated to be spending more than 50% of their weekly incomes on nonmedical expenses, and these patients were found largely in the lower-income categories. A method is proposed for using these data to estimate total nonmedical expenses for different treatment regimens, and also for estimating cancer patients' total nonmedical costs nationally.

Adolescent↗
PubMed1984

Systemic oxygen transport and erythropoiesis in the mouse.

Removal of 15% of blood volume in the mouse increases erythropoiesis by a factor of 2.2 when measured 12 h after bleeding. Exposure of normal mice to 40% reduced barometric pressure for the same period of time increases erythropoiesis only by a factor of 1.6. The response to hypoxia takes place in the presence of a 40% reduction of oxygen consumption and tissue-venous PO2, changes which are concomitant with a 5-fold increase in plasma erythropoietin activity. The larger response in anemic animals on the other hand occurs without any detectable change in these parameters. These results cast serious doubts about the interpretation of the quantitative homeostatic control of erythropoiesis based solely on the action of erythropoietin.

Anemia↗
PubMed1984

A community training scheme in cardiopulmonary resuscitation.

Community instruction in basic life support and resuscitation techniques has been offered in Brighton Health District since 1978. Classes are held frequently for the general public and businesses, schools, and other organisations. First aid care for unconscious patients, the treatment of respiratory obstruction or failure, and the recognition and management of cardiac arrest is taught in a single two hour session. Over 20 000 people have been taught, up to 40 at a time in multiple groups of six to eight, by lay instructors usually supervised by ambulancemen trained to "paramedic" standards. Fifty four incidents have been reported to us in which techniques learnt in the classes have been implemented. Five patients recovered after first aid support but subsequently did not seek medical treatment. Of the 34 patients reviewed in hospital, at least 20 survived to be discharged. We believe that intervention may have been life saving in 16 instances. The benefit of cardiopulmonary resuscitation for victims who may have been asystolic is, however, difficult to quantify because the outcome without intervention cannot be predicted accurately. Community training in basic life support should be considered in association with ambulances equipped for resuscitation and hospital intensive care and cardiac care units as an integrated service for the victims of sudden circulatory or respiratory emergencies. The results achieved so far in Brighton and in other more advanced schemes, particularly in the United States of America, may encourage other health authorities to adopt similar programmes.

Adolescent↗
PubMed1984

Use of specific antibody for rapid clearance of circulating blood background from radiolabeled tumor imaging proteins.

A major problem that arises when radiolabeled serum proteins are used for tumor imaging is the presence of a large amount of circulating background activity that persists for several days. This delays imaging for at least 2 days following injection and necessitates computer subtraction of simulated background (second radiopharmaceutical injection) which introduces artifacts that are difficult to control. We propose here the injection of specific antibody immediately before imaging as an alternate way of reducing blood background through clearance of the immune complex by the liver. 111In-alkyl human transferrin and IgG were injected IV in BALB/c tumor mice, and followed in 18 h by anti-human transferrin and anti-human IgG antibody IV. Two hours later, the tumor and organ distribution of activity was compared with control mice not receiving antibody. 111In-transferrin blood activity was reduced to 1/48 of control with no decrease in tumor concentration: as a result, the tumor to blood ratio increased from 1.4:1 to 78:1. 111In-IgG blood activity was reduced to 1/17 of control, again with no decrease in tumor. The tumor to blood ratios increased from 0.7:1 to 17:1. The liver picked up most of the blood activity with none of the complex going to spleen, bone marrow, or kidney. Dog experiments showed clearance of blood was 90% complete in less than 15 min following antibody injection. Simultaneous scintillation images showed complete clearance of activity from the heart and great vessels in the chest and neck, and over the abdomen, with a concomitant increase in liver activity but no increase in spleen, kidney, or bone marrow activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Freeze-fracture cytochemistry with polymyxin B. A study on the plasma membrane of uterine epithelial cells.

The peptide antibiotic polymyxin B, has been used as a label in a freeze-fracture cytochemical study of anionic phospholipids in the plasma membrane of uterine epithelial cells. The reagent produces mainly circular lesions visible on both P and E faces of fractured membranes. IMPs are found to be associated with lesions and we consider the possible association of integral membrane proteins with anionic phospholipids as well as the mechanisms of lesion formation.

Animals↗
PubMed1984

Natriuretic factor exerts a ouabain-like activity in the rat colon in vitro.

A previously described natriuretic factor (NF) found in urine from man receiving a high salt diet has been postulated to be of hormonal nature. This factor inhibits Na-K ATPase and binds to ouabain receptors. In order to investigate if NF exerts its physiological activity through the Na-K ouabain sensitive pump, its capacity for inhibiting sodium transport has been tested in an in vitro rat colon preparation. Colonic mucosa from rats fed 0.55, 3.55, and 6.55 mmol Na a day were mounted in an Ussing chamber. Inhibition of short-circuit current (SCC) and PD was observed only when NF was added to the serosal side of the membrane and was similar to that observed with ouabain. In rats fed a low or normal salt diet, inhibition of SCC and PD starts after a lag period of 10 min and reaches its maximum inhibition (about 60%) after 90 min. By contrast colonic mucosa from rats receiving a high salt diet exhibits a higher SCC and PD (basal values) and inhibition of the sodium transport starts immediately after addition of NF to the bathing solution. The data demonstrate the similarity of physiological action of ouabain and natriuretic factor on the sodium transport by the colon in vitro. Experiments with rats receiving a high salt diet suggest that by contrast to the kidney, NaCl-dependent cotransport is strongly stimulated by the salt intake in the colon and could be directly inhibited by ouabain or a ouabain-like substance i.e. NF.

Animals↗
PubMed1984

Prostacyclin and thromboxanes in carrageenan-induced pleurisy in the rat.

The cellular origin and kinetics of TXB2 and 6-keto PGF1 alpha in carrageenan-induced pleurisy has been studied. Maximum levels of these prostanoids occurred 1 hour after induction of pleurisy. Mononuclear cells initially present in the pleural cavity synthesized TXB2 and 6-keto PGF1 alpha from (14C) arachidonic acid. By contrast, PMN cells harvested 6 hours after the induction of inflammation did not produce 6-keto-PGF1 alpha. Selective inhibition of thromboxane synthetase with drugs in vitro and in vivo increased the formation of 6-keto-PGF1 alpha, the stable breakdown product of PGI2. This metabolic effect was parallel to an increase in the volume of exudate and in PMN migration. These results suggest that TXA2 seems to be implicated not only as a chemotactic agent but also as an antagonist of PGI2 vasodilator effects.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Search for an endotherm in chloroplast lamellar membranes associated with chilling-inhibition of photosynthesis.

The phase transition of chloroplast lamellar membrane lipids has been proposed to be the underlying cause of chilling-induced inhibition of photosynthesis in sensitive plants. Differential scanning calorimetry has been used to search for any endotherms arising from lipid state changes in chloroplast lamellar membranes of the chilling-sensitive plants cantaloupe , kidney bean, domestic tomato, and soybean. For comparison, calorimetric scans of chloroplast lamellar membranes from the chilling-insensitive plants spinach, pea, and wild tomato were made. A large reversible endotherm, extending from below 10 degrees to nearly 40 degrees C, was observed in chloroplast membranes from tomatoes of both chilling-sensitive (Lycopersicon esculentum Mill. cv. Floramerica ) and chilling-insensitive (L. hirsutum LA 1361) species. A much smaller endotherm, approximately 5 to 10% of the area of that seen in the two tomato species, and extending over a similar temperature range, was detected in chloroplasts from chilling-insensitive spinach and peas, and also was generally observed in chloroplasts from chilling-sensitive cantaloupe , kidney bean, and soybean. The enthalpy of these smaller endotherms indicates that, if the endotherm arose entirely from a lipid transition, then it corresponded to the melting of less than about 10% of the total membrane polar lipid. On the basis of these data it is concluded that there is no correlation between chilling sensitivity of photosynthesis and the presence or absence of a phase transition of bulk membrane lipids of the chloroplast lamellar membrane at temperatures above 5 degrees C.

Chloroplasts↗