Search PubMed⌕ Search

Biomedical subjects

D A Hall

Publications and source records attributed to D A Hall.

At least 55 records · Page 3Linked to original sources
PubMed1996

Computed tomography-guided needle localization of nonpalpable breast lesions: review of 24 cases.

RATIONALE AND OBJECTIVES: We examined the role of computed tomography (CT) in breast imaging, especially in guiding needle localization procedures. METHODS: We reviewed our institution's breast imaging database, from 1978 to 1994, for procedures in which CT scanning was used. Twenty-four CT-guided needle localizations were identified. Medical records, mammograms, CT scans, and pathology reports were reviewed for all patients. RESULTS: Twenty-four needle localizations were performed on 22 female patients. The average size of the lesions localized was 12 mm. The most common reason for CT scanning was the inability to image a suspicious density by conventional mammography on two orthogonal views. Nine malignant and 15 benign lesions were localized under CT guidance. One patient developed a postoperative hematoma. No other complications occurred. CONCLUSION: CT-guided breast localization is a reliable technique that may be used to define selected breast lesions that are difficult to triangulate or localize by conventional two-view mammography.

Aged↗
PubMed1996

Pharmacological analysis of dopamine stimulation of [35S]-GTP gamma S binding via human D2short and D2long dopamine receptors expressed in recombinant cells.

1. The activation of G-proteins by agonist-occupied D2 or D3 dopamine receptors in membranes from recombinant cells expressing the cloned receptors has been analysed by a [35S]-guanosine 5'-[gamma-thio] triphosphate ([35S]-GTP gamma S) binding assay. 2. The rate of [35S]-GTP gamma S binding was increased by dopamine in a dose-dependent manner in membranes from CHO cells stably expressing either the D2short or D2long dopamine receptor. 3. The dopamine-induced stimulation of [35S]-GTP gamma S binding could be inhibited by a range of antagonists. Affinities for antagonists derived from the inhibition of the dopamine stimulation of [35S]-GTP gamma S binding correlated very well with affinities derived from radioligand binding studies. 4. When the maximum [35S]-GTP gamma S binding responses stimulated by dopamine acting at different receptor subtypes were compared, there was a tendency for the stimulation via the D2short receptor to be greater than via the D2long receptor and for the stimulation via the D3 dopamine receptor to be less than for either D2 receptor. These differences in maximal response were also seen when the inhibitory effects of dopamine on adenylyl cyclase via the three receptor subtypes were compared. 5. The stimulation of [35S]-GTP gamma S binding by dopamine in membranes from recombinant cells therefore provides an excellent system for studying the molecular nature of agonism and the receptor/G-protein interactions for these receptors.

Adenylyl Cyclases↗
PubMed1996

Positive predictive value of breast biopsy performed as a result of mammography: there is no abrupt change at age 50 years.

PURPOSE: To determine if the positive predictive value (PPV) of a biopsy initiated because of an abnormal mammogram changes abruptly at age 50 years. MATERIALS AND METHODS: The PPV and its variation with age was analyzed for 4,778 women who underwent biopsy for a clinically occult abnormality detected at mammography. The relationship of the results to the patient's age was analyzed with age represented as a continuous and two-categorized (< 50, > 50) measure. The latter measure represented an abrupt change, which distinguished those aged 49 years and younger from those aged 50 years and over. With this measure, the patients in each of the two age groups were statistically indistinguishable. RESULTS: The results were consistent with a steady increase in PPV and the yield of cancers with age, and there was no abrupt change at age 50 years. The modeled PPV for all cancers for these 4,778 patients was approximately 12% for women aged 40 years and increased to 46% by age 79 years. CONCLUSION: The PPV did not change abruptly at any age for women aged 40-79 years but increased steadily, which reflects the prior probability of breast cancer at each age. Inappropriate grouping of data can lead to misinterpretation of results. Screening guidelines should not be predicated on the false assumption that this variable changes at age 50 years.

Adult↗
PubMed1996

The sternalis muscle: an unusual normal finding seen on mammography.

OBJECTIVE: We studied the appearance of the sternalis muscle on mammography and on CT and MR imaging. To our knowledge, this is the first description of this normal anatomic variant. An approach is provided that permits differentiation of the sternalis from significant pathology. SUBJECTS AND METHODS: Between January 1992 and December 1994, four women of an estimated 32,000 who had mammograms at the Massachusetts General Hospital had an unusual, irregular structure visible medially on the craniocaudal projection that posed a diagnostic dilemma. The records and imaging studies of these women and two others from the Deaconess Hospital breast imaging program were reviewed to determine the etiology of the findings seen by mammography and to establish a diagnostic approach. RESULTS: Surgery in one patient and cross-sectional imaging in the other five established that the structure was the sternalis muscle. Although it may be bilateral, the sternalis muscle was visible only unilaterally on the mammograms of these six women. The appearance of the muscle ranged from an irregularly rounded density at the sternal edge of the film to flame-shaped and almost completely surrounded by fat. CT and MR imaging are diagnostic when they show the longitudinal extent of the muscle, which lies anterior to the medial margin of the pectoralis major muscle. CONCLUSION: The sternalis muscle is an unusual variant of the chest wall musculature. It may be visible as a rounded or irregular density on the craniocaudal mammogram along the sternal edge of the film. With improved mammographic positioning it will be seen more frequently. The muscle has a variety of appearances that should be familiar to the radiologist to avoid confusion with a malignant lesion. The etiology can be confirmed and cancer excluded by CT or MR imaging.

Adult↗
PubMed1996

Physicians' opinions on the delivery of mammographic screening services: immediate interpretation versus double reading.

OBJECTIVE: Mammographic services are delivered in many ways. Emphasis has been placed on providing women with immediate reports of their screening mammograms. We believe that double reading of mammograms is more important than an immediate report. We sought to determine physicians' attitudes toward this issue and if education affects their opinions. MATERIALS AND METHODS: Questionnaires were mailed to 1000 physicians in Massachusetts who were randomly selected from 16,000 members of the state medical society. The questionnaire had four sections, of which two were pertinent to this subject. The first section collected general information on the physician's practice and experience. The second section described two common delivery systems for mammographic screening services and asked physicians to choose the delivery system that would most benefit their patients. RESULTS: Of the 1000 physicians, 294 returned the questionnaire, giving a response rate of 29%. Of these, 16 physicians returned blank surveys, leaving 278 for analysis. Two hundred forty-nine (90%) valued off-site, delayed interpretation of mammographic screening for their patients over on-site reading by a single radiologist if an off-site, delayed reading made double reading possible. CONCLUSION: An off-site, double-reading delivery system for mammographic screening services is preferred by many physicians for their patients once they are educated as to the benefits of double reading.

Adult↗
PubMed1995

Geographic variation of native people along the Pacific Coast.

Data gathered by Boas in the 1890s from 1749 adult males and 1056 adult females were subjected to anthropometric analyses to investigate possible effects of climatic adaptation. The subjects were native people from California, Oregon, Washington, the panhandle of Alaska, and British Columbia. They were categorized by their tribe's latitude and longitude (the center point of tribal distribution) and by habitat (characterized as coastal, western lowlands, and interior). Multiple R regressions were used to determine complex relationships between age, habitat, latitude, rainfall, mean January temperature, mean July temperature, and blood quantum, all of which affected some anthropometric variables to statistically significant degrees in both the male and the female samples. Body size and proportional differences support other studies of Bergmann's and Allen's rules, and variation in the nasal index supports prior studies of selection of longer, narrower noses in cold and dry climates and broader noses in warmer, moister ones. Recent disruption in the central portion of the study area was detectable in reduced size of subjects in these regions. Other complicating factors, such as ethnicity and the possibility of prior migrations and intermarriage between populations, are discussed.

Adaptation, Physiological↗
PubMed1994

Effects of extracellular divalent cations on responses of human blood platelets to adenosine 5'-diphosphate.

The effects of extracellular divalent cations on the responses of human platelets to adenosine 5'-diphosphate (ADP) and on its inhibition by the competitive antagonist adenosine 5'-triphosphate (ATP) were investigated. Two responses were studied, shape change and the inhibition of prostaglandin E1 (PGE1)-stimulated adenylate cyclase, and experiments were carried out in the presence of divalent cations (Ca2+ and Mg2+, 1 mM) or in their absence. For each response there was a small leftward shift of the concentration-response curve to ADP in the absence of divalent cations compared to that in their presence, and this leftward shift disappeared when the results were plotted in terms of ADP3- rather than total ADP concentration. The shape change results were, however, complicated by a reduction in the maximal response to ADP in the absence of divalent cations. For each response there was also a marked increase in the pA2 value of ATP in the absence of divalent cations compared to that in their presence, and this difference disappeared if the results were calculated in terms of ATP4- instead of total ATP. These results suggest that the human platelet ADP receptor, in common with other receptors for adenine nucleotides, recognises predominantly the uncomplexed forms of ADP and ATP as ligands.

Adenosine Diphosphate↗
PubMed1994

Effects of suramin on increases in cytosolic calcium and on inhibition of adenylate cyclase induced by adenosine 5'-diphosphate in human platelets.

The effects of the P2-purinoceptor antagonist, suramin, on ADP-induced increases in human platelet cytosolic calcium concentration ([Ca2+]i) and inhibition of prostaglandin E1 (PGE1)-stimulated adenylate cyclase activity were investigated. Suramin (50-200 microM) acted as an antagonist of ADP-induced increases in [Ca2+]i, causing parallel, rightward shifts of the log concentration-response curve to ADP with no apparent depression of the maximal response. However, the slope of the Schild plot was 2.3 +/- 0.3, similar to that obtained in previous studies on aggregation, indicating that the antagonism was not simply competitive. The apparent pA2 for suramin, taken from the Schild plot, was 4.63, similar to that for suramin's inhibition of aggregation, which suggests that these two effects are closely related. Suramin was not specific for the ADP receptor, however, as it was also able to inhibit, non-competitively, increases in [Ca2+]i induced by 5-hydroxytryptamine. Suramin (50-400 microM) also inhibited the effect of ADP on PGE1-stimulated accumulation of cyclic AMP, causing parallel shifts of the log concentration-response curve to ADP, with a Schild plot slope of 1.00 +/- 0.10, suggesting competitive antagonism, and a pA2 value of 5.09. Suramin (400 microM) did not reduce the inhibition of cyclic AMP accumulation by adrenaline, although it was able to inhibit the accumulation of cyclic AMP caused by PGE1, again showing that suramin has some non-specific effects. These data suggest that suramin is an antagonist at the platelet ADP receptor mediating increases in [Ca2+]i and inhibition of adenylate cyclase, but that it also shows non-specific effects and can depress platelet responses to other agonists. In addition, the similar pA2 value of suramin for the two effects of ADP does not support suggestion that they are mediated by two different receptors on human platelets.

Adenosine Diphosphate↗
PubMed1994

Peroxovanadium compounds. A new class of potent phosphotyrosine phosphatase inhibitors which are insulin mimetics.

Twelve peroxovanadium (pV) compounds, each containing an oxo ligand, one or two peroxo anions, and an ancillary ligand in the inner coordination sphere of V, were synthesized, crystallized, and characterized by 51V NMR as > 95% pure. These compounds activated the insulin receptor kinase (IRK) of cultured hepatoma cells, stimulated lipogenesis in adipocytes, and inhibited the in situ dephosphorylation of autophosphorylated IRs and epidermal growth factor receptors of rat liver endosomes. The phosphotyrosine phosphatase inhibitory and IRK activating potencies of these compounds were linearly correlated (r = 0.74; p < 0.003), decayed in parallel in solution, and varied considerably with the ancillary ligands within these compounds. In vivo administration activated rat liver IRK in parallel with its tyrosine phosphorylation. Co-administration of insulin plus pV was markedly synergistic in both respects. pV administration significantly decreased circulating insulin and plasma glucose concentrations; the latter to levels seen after a dose of insulin yielding > or = 50% occupancy of IRs in vivo. Two compounds (mpV(pic) and mpV(2,6-pdc)) displayed relative specificity as phosphotyrosine phosphatase inhibitors by inhibiting IR dephosphorylation to a significantly greater degree than epidermal growth factor receptor dephosphorylation. Thus, pV compounds are the most potent phosphotyrosine phosphatase inhibitors described to date. Their capacity to activate IRK appears to derive from their phosphotyrosine phosphatase inhibitory activity. Their hypoglycemic action is due to a direct tissue effect.

Adipocytes↗
PubMed1994

Receptors for ADP on human blood platelets.

It is well established that ADP causes aggregation of human blood platelets, and indeed it was the first aggregating agent to be studied, but the ways in which platelets respond to ADP are still relatively obscure. Although it is apparent that increases in intracellular Ca2+ concentrations are of major importance in activating platelets, it is not clearly understood how ADP causes these increases and what other signal transduction mechanisms it uses. It is not even clear whether ADP causes its effects by interacting with only one receptor, or whether multiple receptors for ADP exist on platelets. In this review, Susanna Hourani and David Hall examine some of the conflicting evidence in this field, and draw some tentative conclusions about the number and nature of receptors for ADP on human platelets.

Adenosine Diphosphate↗
PubMed1994

Learning from the experience of loss: people bereaved during intensive care.

In Hartlepool Intensive Therapy Unit (ITU) nurses have recently addressed the needs of relatives while they are visiting the department and afterwards during their bereavement. However in order to determine how best to improve nurses' service we decided to ask those people bereaved their opinions about their experience in order to meet their requirements in the most appropriate way. 16 recently bereaved relatives were interviewed concerning a variety of areas, including information they received in the ITU, support they were given by nurses, how they coped after their loss, and suggestions for improvements. Although this was a small study important areas for improvement were highlighted, and we have now been able to address these further in nursing service and make plans for future developments.

Adaptation, Psychological↗
PubMed1994

Endometrial polyps, hyperplasia, and carcinoma in postmenopausal women: differentiation with endovaginal sonography.

PURPOSE: To characterize endometrial polyps, hyperplasia, and carcinoma with endovaginal ultrasound in postmenopausal women. MATERIALS AND METHODS: Seventy-three postmenopausal women with abnormally thick endometria on endovaginal sonograms were retrospectively identified. The endometrial appearance was characterized as hyperechoic, containing cystic spaces, or heterogeneous. The final study group consisted of 68 women, in whom the pathologic and sonographic findings were correlated. RESULTS: Thirty sonograms showed hyperechoic endometria in women with hyperplasia (n = 8), polyps (n = 4), polyps and hyperplasia (n = 2), or atrophy, proliferative change, mild atypia, or normal endometria (n = 16); 27 sonograms showed cystic spaces in women with polyps (n = 21), carcinoma (n = 1), polyps and hyperplasia (n = 2), or atrophy (n = 3); and 11 sonograms showed heterogeneous endometria in women with endometrial carcinoma (n = 7), atrophy (n = 2), proliferative endometrium (n = 1), or secretory endometrium (n = 1). Cystic spaces were predictive of polyps (P = 1.19 x 10(-10)). CONCLUSION: Endovaginal sonography may be useful for differentiation of endometrial polyps, hyperplasia, and carcinoma.

Aged↗
PubMed1994

A simple device to assist in needle positioning procedures.

At breast biopsy, use of a simple disk that fits into the hub of the needle can facilitate accurate placement of the needle with conventional lesion localization techniques. This disk forms a surface onto which the shadows of the localization crosshairs project so that the operator can advance the needle and maintain its alignment in the direction of the mammography beam by using the field light. The insert has been used successfully in more than 100 procedures.

Biopsy, Needle↗
PubMed1993

Effects of analogues of adenine nucleotides on increases in intracellular calcium mediated by P2T-purinoceptors on human blood platelets.

1. By use of a number of analogues of adenine nucleotides, the structure-activity relationships of the human platelet receptor for adenosine 5'-diphosphate (ADP) mediating increases in intracellular calcium were investigated, and compared with the known structure-activity relationships for induction by ADP of platelet aggregation. 2. ADP, 2-methylthioadenosine 5'-diphosphate (2-methylthio-ADP), adenosine 5'-O-(1-thiodiphosphate) (ADP-alpha-S) and adenosine 5'-O-(2-thiodiphosphate) (ADP-beta-S) each induced increases in intracellular calcium in a manner similar to their reported ability to induce human platelet aggregation. The effects of these agonists were antagonized by ATP, with a pA2 value in each case consistent with the inhibition by ATP of ADP-induced aggregation. In the case of ADP, the inhibition by ATP of increases in intracellular calcium was shown to be competitive by Schild analysis. 3. Of the analogues tested as inhibitors of the effect of ADP on intracellular calcium, 2-chloroadenosine 5'-triphosphate (2-chloro-ATP), adenosine 5'-O-(1-thiotriphosphate) (ATP-alpha-S), P1, P5-diadenosine pentaphosphate (Ap5A) and adenylyl 5'-(beta,gamma-methylene)diphosphonate (AMPPCP) were apparently competitive antagonists, although only one concentration of each antagonist was used. There was a good correlation between the pA2 values found here for these antagonists including ATP, and their pA2 values reported for inhibition of ADP-induced aggregation. Adenosine 5'-(alpha, beta-methylene)triphosphate (AMPCPP) and uridine 5'-triphosphate (UTP) (100 microM) were only very weak inhibitors of the effect of ADP on intracellular calcium, and this is consistent with their weak actions as inhibitors of aggregation. 2-Methylthioadenosine 5'-triphosphate (2-methylthio-ATP) (50 microM) non-competitively inhibited the effect of ADP on intracellular calcium, in a very similar way to its inhibition of ADP-induced aggregation.4. The good correspondence found for these analogues between their effect on intracellular calcium and on aggregation confirms that there is a causal relationship between these actions of ADP, and that they are mediated by the same receptor on platelets. These findings cast further doubt on the use of the affinity reagent 5'-fluorosulphonylbenzoyladenosine (FSBA) as an antagonist and label for the ADP receptor, as this compound has been reported to inhibit aggregation but not ADP-induced increases in intracellular calcium.

Adenine Nucleotides↗
PubMed1993

Mammographically detected breast cancer: location in women under 50 years old.

The mammograms of 86 women under the age of 50 years with mammographically detected cancers were reviewed. Sixty-three of these cancers (73%) were found at the periphery of the breast as defined by a zone 1 cm wide beneath the subcutaneous fat or anterior to the retromammary fat. This finding is likely due to the geometric configuration of the breast. If the breast is hemispheric, then more than 50% of the volume of breast tissue lies within this zone in a large percentage of women. Furthermore, the contrasting adjacent fat likely improves the ability to perceive an abnormality. Interaction of the terminal ducts with chemicals contained within or produced by the fat is a much less likely reason for the high percentage of cancers in this zone. Radiologists should be aware of this phenomenon and pay particular attention to this zone.

Adipose Tissue↗
PubMed1993

Endometrial abnormalities associated with tamoxifen therapy for breast cancer: sonographic and pathologic correlation.

OBJECTIVE: Tamoxifen is widely used to treat breast carcinoma in postmenopausal women. Previous studies have suggested an increased prevalence of endometrial carcinoma and polyps after treatment with tamoxifen. We correlated findings on pelvic sonograms with pathologic findings in a group of patients treated with tamoxifen. MATERIALS AND METHODS: We reviewed the pelvic sonograms and medical histories of 14 postmenopausal women with breast carcinoma who were being treated with tamoxifen. Pathologic correlation was available in the 11 cases in which adequate tissue was obtained. Coexisting pathologic changes were found in seven patients. Pathologic examination showed a total of 18 endometrial abnormalities, including nine cases of uterine polyps, four cases of hyperplasia, two cases of endometritis, one proliferative endometrium, one inactive endometrium, and one case of carcinoma. RESULTS: Sagittal sonograms of all 11 patients with pathologic correlation showed abnormal endometrial thickening measuring more than 7 mm. The sonographic appearance of the endometrium in these patients included hyperechoic, homogeneous tissue; hyperechoic tissue with multiple, small cystic spaces; heterogeneous tissue with small cystic spaces; and solid tissue that was heterogeneous. Small cystic spaces were seen in all cases of polyps. Six of the nine cases of polyps were associated with other endometrial abnormalities also. The single case of endometrial carcinoma appeared solid and heterogeneous on sonography; however, further pathologic examination of the surgical specimen showed a coexisting polyp. CONCLUSION: Tamoxifen therapy is associated with several findings on sonograms of the uterus. Because several pathologic findings frequently coexist, sonography is of limited use in the diagnosis of specific abnormalities.

Aged↗
PubMed1992

Breast cancer survival among women under age 50: is mammography detrimental?

Great uncertainty exists about the benefit of detecting breast cancer by mammography in women under 50 years of age. We have reviewed the survival of patients aged 49 years or less whose cancers were detected by mammography alone. 117 women under the age of 50 years were diagnosed with breast cancer between 1978 and 1991 based only on an abnormal mammogram. Ductal carcinoma in-situ (DCIS) was found in 47 (40%) of these women, whilst 70 (60%) had infiltrating ductal or infiltrating lobular carcinomas. During the same interval, 928 women in this age group presented with palpable breast cancer. DCIS was diagnosed in 82 (9%) of these women, whilst 846 (91%) had infiltrating carcinoma. Among the infiltrating cancers detected by mammography alone, 50% were stage I, whilst only 30% of the women with palpable cancers were stage I. Five-year survival for all mammographically detected cancer patients was 95%, whereas for women with palpable cancers the survival was 74% (p < 0.00005). If DCIS is not included, the corresponding survivals are 91% for mammographically detected infiltrating cancers and 72% for palpable infiltrating cancers. Only 1 woman who died among those with palpable cancer had had a mammogram before diagnosis. Our data contradict the suggestion that women under 50 are put at a survival disadvantage by undergoing mammography. We believe that investigators who have reported negative results in this age group must examine other causes for their results.

Actuarial Analysis↗