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Biomedical subjects

M Baum

Publications and source records attributed to M Baum.

At least 307 records · Page 17Linked to original sources
PubMed1991

The cytogenetic and molecular architecture of chromosome 1R--one of the most widely utilized sources of alien chromatin in wheat varieties.

Chromosome 1R of rye (Secale cereale) is one of the most intensively used sources of alien chromatin in bread wheat. It provides a source of valuable disease resistance genes and its widespread use has stimulated the development of genetic maps incorporating protein and DNA markers. Published data as well as new mapping data were combined into a consensus map by using common markers in the different mapping studies to orient the various data sets relative to each other. The consensus map provides a tentative order, and relative distances, between the genetic markers. A summary of the dispersed repetitive sequences that are now available for the detection and characterization of chromosome 1R segments in wheat is also provided.

Base Sequence↗
PubMed1991

Fibrous mastopathy in insulin dependent diabetics.

The cases of two poorly controlled insulin dependent diabetic women, presenting with hard discrete breast lumps clinically suspicious of carcinoma are presented. Mammography revealed dense dysplastic parenchymal changes with no specific features of carcinoma and ultrasound showed acoustic shadowing but no discrete mass. Excision biopsy of these lumps was performed. Histologically they were benign, and were composed of fibrous tissue with a chronic inflammatory cell infiltrate. With better awareness of fibrous mastopathy which can occur in this group of diabetic patients, and with the absence of specific radiological features of malignancy, some of these women may be observed and spared excision biopsy.

Adult↗
PubMed1991

The mammographic parenchymal patterns of nulliparous women and women with a family history of breast cancer.

One-hundred-and-thirteen mammograms of nulliparous women and 44 mammograms of women with a family history of breast cancer were graded according to Wolfe's parenchymal pattern classification. These were compared to 437 mammograms of women without these risk factors. Mammograms were read by two independent observers in order to evaluate inter- and intra-observer variation. The interobserver variation was reduced from 17% to 5% by combining high risk patterns (P2 and DY) and low risk patterns (N1 and P1). A significantly higher proportion of high risk patterns was found in nulliparous women compared to parous women (P less than 0.01). The proportion of high risk patterns decreased significantly with the number of children (P less than 0.01). Women with a family history of breast cancer had almost the same parenchymal patterns as women without a family history. In conclusion, while nulliparity and family history are recognized risk factors for developing breast cancer, only nulliparity would appear to influence the mammographic parenchymal pattern. This probably reflects the different mechanism by which the two factors affect breast tissue.

Breast Neoplasms↗
PubMed1991

The mammographic parenchymal patterns of women on hormonal replacement therapy.

In this study 383 mammograms of women on hormone replacement therapy (HRT) for more than one year and 216 mammograms of women performed before HRT was started were examined to identify any mammographic features which are associated with a higher incidence of developing breast cancer according to Wolfe's criteria. There was no significant difference in the proportion of high and low risk parenchymal patterns as the duration of HRT increased. A significantly higher proportion of low risk patterns with ageing was observed in 216 women who had never been on HRT when compared to 194 mammograms of women who had been on HRT for more than 5 years. This difference becomes more obvious in women on HRT with less than three children compared to a similar group not taking HRT. Women who had not taken HRT appeared to undergo normal involutional changes which were reflected by an increase in the proportion of low risk patterns with increasing age. We may conclude from these findings that HRT appears to inhibit involutional processes within the breast and therefore this group have higher risk parenchymal patterns for a longer period of time and subsequently may have a higher risk of developing breast cancer.

Age Factors↗
PubMed1991

Caregiving and multigenerational families.

This paper examines the possibility that the extension of traditional family household boundaries foreshadows an expanded caregiving system as family lines grow longer. An original study of 25 four-generation families, mapping all linear and lateral members, offers findings that confirm evidence found in a literature review. One primary caregiver, either a spouse or daughter, generally shoulders responsibility for members in adversity. A caregiving system encompassing more than two generations in direct descent was not discernible. Problems in caring for the oldest old are noted.

Adolescent↗
PubMed1991

Social support networks of white and black elderly people at risk for institutionalization.

The literature examining the role of social network size and support in moderating the relationship between stress and illness in the aged population has not taken racial differences into account. This study compares the potential moderating influence of social network size and support on the relationship between life stress and depressive symptoms for black and white community-dwelling elderly people at increased risk for institutionalization. Study data come from in-person interviews with a sample of 191 old-old (75 years and older) and poor residents of a three-census-tract area in Pittsburgh. Approximately 50 percent were white and 50 percent were black. Results indicate that the moderating effects of social network size and support were different for the black people than for the white people in this sample. For white aged people, having greater social support and a larger social network reduces the association between stress and depressive symptoms, as expected. For black elderly people, however, having more network members and receiving support from them is associated with a stronger relationship between stress and depressive symptomatology.

Black or African American↗
PubMed1991

Prospects for the chemoprevention of breast cancer.

Breast cancer is by far the most common type of cancer in women accounting for 20% of all new cases. It is estimated that 1 in 12 women will develop breast cancer at some time in their life. Each year in the UK, 24,500 women are newly diagnosed with breast cancer and 15,000 women die from it. The incidence rates rise from less than 10 per 100,000 women aged under 30 years to 300 per 100,000 in women aged over 85 years. The seriousness of the problem is emphasized by the fact that for women aged 35-54 years, breast cancer is the commonest single cause of all death. Both the incidence and the mortality have slightly increased in recent years, although mainly in the older age groups. There has been a slight decrease in the mortality rates for women aged 15-44 years over the last 35 years, but in all the older age groups there have been increases.

Adolescent↗
PubMed1991

Prenatal glucocorticoids stimulate neonatal juxtamedullary proximal convoluted tubule acidification.

The rate of neonatal proximal convoluted tubule (PCT) HCO3 absorption is lower than that of adult animals. The present in vitro microperfusion study examined whether prenatal dexamethasone (60 micrograms/kg daily to the doe for 3 days before delivery) would accelerate the maturation of neonatal juxtamedullary PCT acidification. Control neonates studied within 48 h of birth had a urine pH of 7.06 +/- 0.15 and a urine HCO3 concentration of 34.3 +/- 7.0 meq/l. Animals receiving dexamethasone had a urine pH of 6.47 +/- 0.11 and a urine HCO3 concentration of 10.1 +/- 4.0 meq/l, both of which were significantly lower than control (P less than 0.01). In juxtamedullary PCTs perfused in vitro, volume absorption was 0.27 +/- 0.03 nl.mm-1.min-1 in controls and 0.39 +/- 0.02 nl.mm-1.min-1 in dexamethasone-treated animals (P less than 0.05). HCO3 absorption was stimulated in the dexamethasone group (52.6 +/- 4.6 vs. 34.1 +/- 6.3 pmol.mm-1.min-1, P less than 0.05); however, glucose transport was not significantly affected (24.8 +/- 1.3 in dexamethasone vs. 21.5 +/- 3.5 pmol.mm-1.min-1 in controls). Intracellular pH was measured using 2',7'-bis(carboxyethyl)-5(6)-carboxyflourescin to examine whether prenatal dexamethasone stimulated the apical Na(+)-H+ antiporter and the basolateral Na(HCO3)3 symporter. Apical Na(+)-H+ antiporter proton flux was 108.5 +/- 14.2 pmol.mm-1.min-1 in the control group and 250.7 +/- 31.3 pmol.mm-1.min-1 in the dexamethasone group (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The growth inhibition of human breast cancer cells by a novel synthetic progestin involves the induction of transforming growth factor beta.

Recent experimental work has identified a novel intracellular binding site for the synthetic progestin, Gestodene, that appears to be uniquely expressed in human breast cancer cells. Gestodene is shown here to inhibit the growth of human breast cancer cells in a dose-dependent fashion, but has no effect on endocrine-responsive human endometrial cancer cells. Gestodene induced a 90-fold increase in the secretion of transforming growth factor-beta (TGF-beta) by T47D human breast cancer cells. Other synthetic progestins had no effect, indicating that this induction is mediated by the novel Gestodene binding site and not by the conventional progesterone receptor. Furthermore, in four breast cancer cell lines, the extent of induction of TGF-beta correlated with intracellular levels of Gestodene binding site. No induction of TGF-beta was observed with the endometrial cancer line, HECl-B, which lacks the Gestodene binding site, but which expresses high levels of progesterone receptor. The inhibition of growth of T47D cells by Gestodene is partly reversible by a polyclonal antiserum to TGF-beta. These data indicate that the growth-inhibitory action of Gestodene may be mediated in part by an autocrine induction of TGF-beta.

Binding Sites↗
PubMed1991

Role of adenosine triphosphate (ATP) and NaK ATPase in the inhibition of proximal tubule transport with intracellular cystine loading.

Cellular cystine loading with cystine dimethyl ester inhibits volume absorption, transepithelial potential difference, glucose transport, and bicarbonate transport in proximal convoluted tubules perfused in vitro. This study examined the roles of ATP and NaK ATPase in this in vitro model of the Fanconi syndrome of cystinosis. Intracellular ATP was measured using the luciferin-luciferase assay. Intracellular ATP was reduced by 60% in proximal convoluted tubules incubated with 0.5 mM cystine dimethyl ester for 15 min at 37 degrees C (P less than 0.001). Incubation of cystine loaded tubules with 1 mM exogenous ATP increased intracellular ATP to levels not significantly different than that of controls. On the other hand, Vmax NaK ATPase activity was unchanged even though the incubation times and the concentration of cystine dimethyl ester were doubled to 30 min and 1 mM, respectively. In proximal convoluted tubules perfused in vitro, 0.5 mM cystine dimethyl ester resulted in an 89% inhibition in volume absorption (0.81 +/- 0.14 to 0.09 +/- 0.09 nl/mm.min), while there was only a 45% inhibition in volume absorption (P less than 0.01) due to cellular cystine loading in the presence of 1 mM lumen and bath ATP (0.94 +/- 0.05 to 0.52 +/- 0.11 nl/mm.min). These data demonstrate that proximal tubule cellular cystine loading decreases cellular ATP concentration, but does not directly inhibit NaK ATPase activity. The inhibition in transport and decrease in intracellular ATP due to cellular cystine loading was ameliorated by exogenous ATP. These data are consistent with cellular ATP depletion playing a major role in the inhibition of proximal tubule transport due to intracellular cystine loading.

Adenosine Triphosphate↗
PubMed1991

Effects of growth hormone and insulin-like growth factor I on rabbit proximal convoluted tubule transport.

This in vitro microperfusion study examined the effects of growth hormone and insulin-like growth factor I (IGF-I) on proximal convoluted tubule (PCT) transport. Tubules were perfused with an ultrafiltrate-like solution and bathed in a serum-like albumin solution. Neither a physiologic (5 x 10(-10) M), nor a pharmacologic (5 x 10(-8) M) dose of growth hormone had an effect on PCT phosphate or bicarbonate transport, or volume absorption. Addition of 5 x 10(-9) M and 5 x 10(-8) M IGF-I, but not 5 x 10(-10) M IGF-I, to the bathing solution resulted in an increase (12-15%) in phosphate transport, but no change in volume absorption or bicarbonate transport. Addition of IGF-I to the luminal perfusate also stimulated phosphate transport. The effect was noted at a concentration of 5 x 10(-11) M IGF-I (27% stimulation) and was maximal at a concentration of 5 x 10(-10) M IGF-I (46% stimulation). There was no effect of luminal IGF-I on volume absorption or bicarbonate transport. These data indicate that growth hormone has no direct effect on PCT transport. In the PCT, IGF-I stimulates phosphate transport specifically and acts via both basolateral and apical membranes. However, the magnitude of the maximal response to the luminal addition of IGF-I was threefold greater than that measured upon addition of the hormone to the bath, and the stimulation occurred at a 100-fold lower concentration. These data are consistent with IGF-I mediating the in vivo stimulation of phosphate transport by growth hormone.

Animals↗
PubMed1991

Dilemmas facing surgical research in the '90s.

Surgical research in the '90s will need to address several general problems. This paper discusses the role of informed consent in clinical trials, animal experimentation in surgical research, and the importance of research in both undergraduate and postgraduate education.

Animal Testing Alternatives↗
PubMed1991

Significance of 'Langer's axillary arch' in axillary dissection.

The axillary arch is reported to occur in 7% of the population, but in our experience has only been observed in 0.25%. The anatomical features are described and its importance in axillary dissection is indicated. In addition, its relevance to the prevention of lymphoedema and to the construction of latissimus dorsi flaps is discussed. The axillary arch should be considered in the differential diagnosis of axillary swellings.

Axilla↗