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Biomedical subjects

J A Martin

Publications and source records attributed to J A Martin.

At least 145 records · Page 8Linked to original sources
PubMed1986

The in vitro effects and cross-resistance patterns of some novel anthracyclines.

A range of new anthracyclines, structurally related to adriamycin (ADM), has been synthesised and studied in vitro. Three compounds described in this paper (Ro 31-1215; Ro 31-1741; Ro 31-2035) are all 4-demethoxyanthracyclines. In the mouse mammary tumour cell line, EMT6/Ca/VJAC, using a 1 h drug exposure followed by colony formation as the response endpoint, we found Ro 31-1215 and Ro 31-1741 to be 2-3 x and 4-7 x more potent then ADM, whilst Ro 31-2035 was 3-4 x less potent. For continuous drug exposure and suppression of population growth as the endpoint, the potency of Ro 31-1741 was similar to that of ADM, whereas that of Ro 31-1215 was 1.5-2 x higher and that of Ro 31-2035 was 10-20 x lower. The potency ratios for continuous drug exposure of a human small cell lung cancer line were similar to those for continuous exposure of EMT6. Variants of the two cell lines selected for resistance to ADM were also studied. These variants also showed considerable resistance to Ro 31-1741 and Ro 31-2035 but much less resistance to Ro 31-1215 (a 9-methyl derivative). A variant of EMT6 made resistant to Ro 31-1215 by continuous growth in this drug was more resistant to ADM than it was to Ro 31-1215. Human cells resistant to ADM contained 6 x less ADM after 24 h exposure than did the parent line, whereas the ratio of drug content for Ro 31-1215 was only 2.

Animals↗
PubMed1986

Calcium and ATPase activity during hepatic intoxication with thioacetamide.

The effects of acute thioacetamide (TAA) intoxication on the calcium, magnesium, sodium and potassium content of liver and on its ATPase activities were studied in rats. Samples of liver were analyzed by atomic absorption spectrometry for their cationic content 6, 24 and 48 h after administration of TAA through a stomach tube. After sonification other samples were assayed for (Na+ + K+)-dependent, (Ca2+ + Mg2+)- and Ca2+-dependent ATPases. No apparent correlation has been found between the increased hepatic calcium after TAA treatment and the variations of ATPase activity. Both calcium movement and ATPase activity appear sex-determined. These results bring support to the hypothesis that an interaction between TAA or its metabolites with the cell membrane provokes an increased influx of extracellular calcium. The relationship between this calcium increase and the changes in ATPase activity with the events triggering the neoplastic transformation is discussed.

Acetamides↗
PubMed1985

Fusion of low density lipoproteins with cholesterol ester-phospholipid microemulsions. Prevention of particle fusion by apolipoprotein A-I.

Little is known about the mechanism and control of lipoprotein particle fusion, although apoproteins are presumed to be important in maintenance of particle structure. This study characterizes the interaction of apo-B-containing low density lipoproteins (LDL) with cholesterol ester microemulsions (CEME) in the presence and absence of apo-A-I to determine if a role for these apoproteins in particle integrity could be ascertained. CEME are an apoprotein-free analog of LDL formed by sonication of radiolabeled phospholipid (surface) and cholesterol ester (core). Incubation of CEME with LDL followed by precipitation of LDL with MnCl2 resulted in coprecipitation of CEME with LDL that was time-, temperature-, and concentration-, but not pH (pH 6-9)-, dependent and occurred over a wide range of CEME and LDL particle compositions. Particles from the incubation were larger than the unincubated particles and intermediate in density and electrophoretic mobility between the starting LDL and CEME. Differential scanning calorimetry experiments suggested that CEME surface and core lipids had mixed with those of LDL. When particles from incubations were exposed to an anti-apo-B column, radiolabeled surface and core molecules originating from the CEME particles bound to the column. Particles eluted at low pH from the anti-apo-B column were irregularly shaped and had excess surface material as judged by electron microscopy. Incubation of CEME with LDL in the presence of 3 M KBr or 4% bovine serum albumin did not alter the interaction of the particles. However, incubation of CEME with LDL in the presence of apo-A-I (2:1 CEME cholesterol-to-apo-A-I mass ratio) greatly reduced the interaction of the LDL and CEME particles. We conclude that the incubation of CEME with isolated LDL resulted in particle fusion that was prevented by apo-A-I.

Apolipoprotein A-I↗
PubMed1985

Chest physiotherapy in acute bronchiolitis.

Forty four children with acute bronchiolitis were given twice daily chest physiotherapy in addition to standard supportive measures and were compared with 46 controls who were not given physiotherapy. There was no clinically discernable benefit on the course of their illness.

Acute Disease↗
PubMed1984

Mineral metabolism and in vivo uptake of [67 Ga]citrate.

The uptake of [67 Ga]citrate by normal rats of different ages has been compared with the mineral composition of the assayed tissues. Very young animals take up much more 67 Ga than the adults and there seems to be a correlation between the mineral composition (calcium, magnesium and iron) and the radioactivity uptake. The role of those elements and of cellular proliferation in this phenomenon is discussed.

Animals↗
PubMed1984

Neglected fathers: limitations in diagnostic and treatment resources for violent men.

In its examination of violent activity within the family, current literature assumes a "pecking order" exists: Larger and stronger family members attack those who are smaller and weaker. Adult males are usually studied as primary maltreaters of spouses, while females are considered mainly responsible for physically abusive behavior with children. Use of this perspective has led to neglect of male abusers, who injure half of the mistreated children in the United States. Through assessment of 66 studies of child abuse published during a 5-year period, this paper documents the lack of attention abusive fathers have received. Twenty-eight of these studies included only mothers, while two dealt exclusively with fathers. Most of the 36 remaining two-parent studies did not discuss sex differences. No diagnostic categories consistently differentiated male from female abusers. No study discussed specialized treatment needs of women and men. This survey suggests that the therapeutic field considers the child's mother the primary responsible parent, even though she may not be the perpetrator of violence in the family. As a result, inadequate treatment resources have been made available to maltreating fathers. The survey points to the need for much more comprehensive research comparing male and female maltreaters.

Adult↗
PubMed1984

Advances in behavioral approaches to adolescent health care.

Behavior change professionals have developed treatment programs for a wide variety of health care problems affecting adolescents. Although a substantial data base of experimentally tested techniques exists for obesity, smoking prevention, and dysmenorrhea, much work remains in other areas. For example, the case studies reported on neurodermatitis and the survey work in teenage alcohol abuse must give way to systematic interventions employing group experimental designs. In addition, behavioral procedures should be compared to other treatments. Also, component analysis should be performed when multiple treatment strategies are used. Finally, strategies aimed at increasing the generalization of treatment, such as from classrooms to different community settings in substance abuse prevention programs and maintenance of treatment effects over long follow-up periods, are necessary. Only in this way will the efficacy of behavioral interventions for specific health problems be established. The leading causes of mortality among adolescents are due to accidents. Of the total number of deaths due to accidents, approximately 50% are attributed to motor vehicle accidents (National Safety Council, 1977). Many of these accidents are due to negligence, substance abuse, and, in general, immature behavior (Bakwin & Bakwin, 1972). In spite of a slow but consistent trend toward lower accidental deaths over time (National Safety Council, 1977), there still is a need for interventions designed to decrease risk-taking behavior, substance abuse, and carelessness in adolescents. Again, behavior change professionals might follow the example set by researchers who have begun to develop successful strategies for decreasing onset of cigarette smoking. These interventions and research methods, designed for use in schools, may provide a promising approach for addressing other kinds of prevention problems. It also seems appropriate to categorize cigarette smoking not only as a risk factor in the development of cardiovascular disease (Kuller, 1976), but also as a member of the risk-taking behaviors. Thus, procedures used to prevent cigarette smoking might also be adapted to prevent other kinds of risk-taking behaviors among adolescents. The work of McAlister et al. (1980), in preventing alcohol abuse as well as cigarette smoking by use of the same or similar procedures, is a case in point. Use of a procedure designed to train competency in refusing peer pressure has clear implications for reducing other risk-taking behaviors, such as reckless driving, drug abuse, and swimming and boating accidents.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1984

Sexual maturation, social class, and the desire to be thin among adolescent females.

Veblen's 1899 hypothesis that associated a female desire for thinness with the higher social classes was tested with data from a representative national sample of adolescents, 12 to 17 years of age, in the National Health Examination Survey. Controlling for the actual level of fatness, adolescent females in higher social classes wanted to be thinner more often than those in lower classes. The greater female desire for thinness was not the product of health information nor of sex differences in the level of fatness. The thinner the female, the greater the impact of social class on the desire for thinness. During puberty, adolescent females negatively evaluated the body fat associated with normal sexual development.

Adolescent↗
PubMed1983

Extrascleral extension of choroidal melanoma diagnosed by ultrasound.

Four cases of choroidal melanoma with extrascleral extension are presented. In each case, contact B-scan ultrasonography identified extrascleral extension of choroidal melanoma as an area of relative echolucency immediately behind the globe. These ultrasonographic findings are contrasted with those demonstrated by computerized tomography. The importance of B-scan ultrasonography in the assessment of a patient with possible choroidal melanoma is discussed.

Adult↗
PubMed1983

Direct computer recording of premature infants and nursery care: distress following two interventions.

Prematurely born neonates are born with an immature central nervous system. Temporal associates between care-giver interventions and infant biobehavioral responses can be recorded. A new methodology for continuous naturalistic computer-assisted recording of infants in nursery care is described. To illustrate a clinical implication of this recording, an infant's responses to two seemingly contrasted care-giver interventions were analyzed: chest physical therapy and close social interaction. There was significantly increased subtle as well as gross behavioral and physiologic distress following both chest physical therapy and close social interaction when compared with base line distress incidence. Perhaps timing of interventions is as consequential as their content toward safeguarding a preterm infant's developing autonomic regulation, motor patterns, and sleep/wake state.

Computers↗
PubMed1982

Educational correlates of early and late sexual maturation in adolescence.

From the National Health Examination Survey data, 4,735 Caucasian males and females, 12 to 17 years, were classified by age and stage of sexual maturation (Tanner). Early and late maturers were each compared to all other youth of comparable age and sex, in eight education-related categories: youth and parental aspirations and expectations concerning the level of education which would be achieved by the student, teacher reports of intellectual ability and academic achievement, and test scores (WISC and WRAT). Except at age 12, late maturing boys received significantly lower ratings than mid maturers in all these areas, and early maturing males received higher ratings. For females, no differences persisted across age groups. In advising male adolescents, physicians should be alert to the possibility that school functioning may be linked to maturational processes.

Achievement↗
PubMed1982

Aetiological factors relating to childhood deafness in the European community.

A multinational collaborative study on deaf children was carried out in 1977. The intention was to include all children aged 8 years with a hearing loss of 50 dB or worse, residing in the nine countries of the European Economic Community. Information was obtained on the prevalence of deafness, the distribution of mean hearing loss, aetiology and associated disabilities.

Child↗
PubMed1982

Diagnosis and communicative ability in deaf children in the European Community.

The survey of Childhood deafness carried out during 1977 in the nine countries of the European Economic Community (EEC) provided data on the age at which diagnosis is achieved, the patterns of hearing aid provision, the types of school environment, speech and reading abilities, and the use of manual communication.

Age Factors↗
PubMed1982

Application of structural modeling with latent variables to adolescent drug use: a reply to Huba, Wingard, and Bentler.

I propose that strong claims about the superiority of latent variable (LV) structural modeling, compared to other causal approaches to nonexperimental data, are both overstated and premature. Focusing primarily on a recent article by Huba, Wingard, and Bentler (1981) appearing in this journal, I argue both that the authors' application of these models is seriously flawed and that the data employed to test the models are of questionable quality. I conclude that statements about powerful inferences that can be made from analyses of LV models should be moderated. A more prudent position is advocated in this paper: I argue that the evaluation and testing of LV models should proceed, but with caution and self-criticism; even highly sophisticated methods like LV modeling cannot substitute for the collection of high quality data and the clear operationalization of constructs and hypotheses.

Adolescent↗