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Biomedical subjects

D A Hall

Publications and source records attributed to D A Hall.

At least 19 recordsLinked to original sources
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↗
PubMed1992

Effects of the P2-purinoceptor antagonist, suramin, on human platelet aggregation induced by adenosine 5'-diphosphate.

1. The effects of suramin, a trypanocidal drug which has been reported to be a P2-purinoceptor antagonist on smooth muscle, were investigated in human platelets, where adenosine 5'-diphosphate (ADP) induces aggregation by acting on a subtype of purinoceptors which has been called P2T. 2. Suramin (100 microM) had no inhibitory effect on ADP-induced platelet aggregation in plasma, even after 40 min incubation in the presence of bacitracin, a peptidase inhibitor, and did not affect the ability of adenosine 5'-triphosphate (ATP) (40 microM) to inhibit competitively ADP-induced aggregation. This lack of effect of suramin on platelets in plasma is probably due to its extensive binding to plasma proteins. 3. In washed platelets, suramin (50-400 microM) acted as an apparently competitive antagonist, causing parallel shifts to the right of the log concentration-response curve to ADP. No depression of the maximal response to ADP was observed at concentrations of suramin (50-150 microM) for which full log concentration-response curves to ADP could be obtained, but the slope of the Schild plot was around 2, indicating that this antagonism was not simply competitive. The apparent pA2 value for suramin, taken from this Schild plot, was 4.6. 4. Suramin (200-400 microM) also noncompetitively inhibited aggregation induced by U46619 (a thromboxane receptor agonist) or by 5-hydroxytryptamine in the presence of adrenaline (100 microM), and caused a depression of the maximal response to these agonists. This nonspecific effect of suramin may explain the high Schild plot slope obtained against ADP.5. These results provide evidence that the ADP receptor on human platelets is indeed similar to the P2-purinoceptors responding to adenine nucleotides on smooth muscle and other tissues, and show that suramin cannot distinguish between the proposed subtypes of the P2-purinoceptors.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1992

Calcified suture material in the breast after radiation therapy.

Of 335 women who underwent lumpectomy and radiation therapy for breast cancer, 42 subsequently developed calcifications. Particles typical of calcified suture material were identified in 21 of the 42 women (50%). No obvious calcified suture material was found in approximately 1,140 women of 38,000 (3%) who had undergone mammography after they had previously undergone breast biopsy for a benign lesion and thus had not undergone radiation therapy. Calcified suture material rarely develops in the nonirradiated breast, but it is common after radiation therapy and should not be confused with recurrent breast cancer. These calcifications are likely the result of delayed resorption of catgut sutures, which provide a matrix on which calcium can precipitate in a suitable local environment.

Breast Neoplasms↗
PubMed1991

Mediastinal abnormalities: detection with storage phosphor digital radiography.

Conventional film radiography (FR) and six postprocessing algorithms of isodose storage phosphor digital radiography (SR) (0.2-mm X 10-bit pixel matrix) were compared in the evaluation of 40 mediastinal and 30 pulmonary lesions in 60 patients who underwent computed tomography of the chest. The six SR algorithms varied among each other in only one image parameter. One algorithm approximated conventional image characteristics. The other five algorithms were designed to optimize imaging of the mediastinum and tested the effects of gray-scale reversal, adjustment of optical density, a linear instead of a sigmoid gradation curve, and moderate edge enhancement of high and medium spatial frequencies. Performance was evaluated by calculating the average area under the receiver operating characteristic curve (Az) of 5,040 observations by six readers. Post-processing with high-frequency edge enhancement and density optimization for the mediastinum significantly improved performance of SR over FR in the detection of mediastinal lesions (Az = .80 +/- .02 vs .73 +/- .01, respectively). Gray-scale reversal significantly decreased performance (Az = .64 +/- .03). All SR algorithms that were postprocessed to optimize imaging of the mediastinum were significantly inferior to FR in the detection of pulmonary lesions.

Algorithms↗
PubMed1991

Hysterosalpingography in the 1990s.

All physicians involved in the evaluation and treatment of infertility rely heavily on the information provided by hysterosalpingography. For many years this study has provided images of the lumina of the fallopian tubes that are not available by other diagnostic means, and it also gives the most accurate outline of the uterine cavity. Hysterosalpingography will therefore continue to be a valuable study in the upcoming decade, and it is important now to take account of the many advances in technology that impinge on the execution and interpretation of this study. In this article we first update the continuing debate about elements of the study itself, involving techniques and the choice of contrast material. We also consider surgical advances, such as the widespread use of microsurgical reconstruction of the fallopian tube, that increase the demand for hysterosalpingography. Since radiologists are asked to evaluate the results of surgery, it is essential for them to be familiar with the postoperative appearances of the fallopian tube. Finally, we consider what must be by far the most important development of the 1990s, the continuing integration of hysterosalpingography with new interventional and imaging techniques. Fallopian tube catheterization expands the examination of the fallopian tube and offers new therapeutic applications. Transvaginal sonography and MR imaging have allowed noninvasive exploration of the female pelvis. Correlation of hysterosalpingography and MR imaging is particularly useful in the diagnosis of uterine myomas and congenital uterine duplication anomalies when surgery to preserve or enhance the reproductive capacity of the uterus is indicated. Sonography and MR imaging should be correlated with hysterosalpingography to provide a more efficient diagnostic and therapeutic approach to the common mechanical causes of infertility.

Catheterization↗
PubMed1991

Should etching be performed as a part of a vital bleaching technique?

Many clinicians advocate etching the teeth before vital bleaching as a way to enhance the permeability of the tooth surface to hydrogen peroxide and thus to enhance the bleaching effect. However, no studies have been published to date to document the effect of etching on vital bleaching. In this study, ten patients received a bleaching treatment regimen of several appointments. Half of the teeth in one arch of each patient were etched with phosphoric acid for 20 seconds before they were bleached with 35% hydrogen peroxide. The teeth in the other half of the same arch were treated with tap water prior to bleaching. Evaluations of the patients after 3 and 6 weeks failed to confirm any enhanced lightening effect from etching.

Acid Etching, Dental↗
PubMed1979

Mittelschmerz. Sonographic demonstration.

Ultrasonography of the pelvis at mid-menstrual cycle in normal women has demonstrated small quantities of free fluid in 40% of cycles. Two thirds of the cycles associated with pain had ultrasonically demonstrated fluid at ovulation. These sonographic findings at Mittelschmerz confirm the physiological trauma of ovulation.

Diagnosis, Differential↗
PubMed1979

Computed body tomography in chronic pancreatitis.

CT of the pancrease permitted correct positive diagnosis in 28/50 or 56% of patients with chronic pancreatitis proved by laparotomy or retrograde ductography. Diagnoses were based on CT identification of one or more specific hallmarks of chronic pancreatitis including calcifications (18/50 or 36%), parenchymal atrophy (7/50 or 14%) and pancreatic duct dilatation (2/50 or 4%), as well as the principal surgical complications, pseudocyst and abscess (15/50 or 30%). In 9 patients, CT disclosed pancreatic calcifications not visible on conventional radiographs. In 32 patients, ultrasound was less informative than CT giving a correct diagnosis in 8 pseudocycts (25%). In the patient with unexplained upper abdominal complaints, a positive CT diagnosis of chronic pancreatitis permits more confident patient management than a negative, or "no tumor" diagnosis rendered by other noninvasive examinations.

Chronic Disease↗
PubMed1979

Sonographic morphology of the normal menstrual cycle.

Sequential gray-scale sonograms were obtained during 20 menstrual cycles in 16 normal female volunteers. Hormonal and physical parameters of an ovulatory cycle were correlated with morphological changes in the ovaries, uterus, and cul-de-sac as seen on the sonogram. Ovarian cysts of two sizes were observed, corresponding chronologically and morphologically to Graafian follicles and corpora lutea. Small amounts of free pelvic fluid were demonstrated in many women at ovulation. A characteristic uterine appearance is seen prior to menstruation and is related to hormonal influences on the uterus. These findings emphasize the importance of recognizing normal physiological changes when interpreting gynecologic sonograms.

Douglas' Pouch↗
PubMed1978

Clinical application of a single compartment model to urea and creatinine kinetics in dialysis therapy.

A single compartment mathematical model has been shown to accurately described changing serum concentrations of low molecular weight solutes (urea and creatinine) during dialysis. Clinical application of the model permits prediction of serum concentrations in response to changes in prescription of dialysis therapy. The programs presented here can be used to predict the effect of changes in treatment time and dialyzer clearance on serum concentrations. Sequential pre- and end-dialysis solute concentrations are displayed on a programmable pocket calculator. Dialyzer clearance during any individual dialysis can be calculated. These programs permit an evaluation of the efficacy of prescribed dialysis treatment schedules in advance of therapeutic trials.

Computers↗
PubMed1978

Scanning techniques in computed body tomography.

Clinical examinations with the whole body CT scanner require considerable individualization of examination technique in relation to specific organs, anatomic areas, and clinical problems. Careful selection of radiographic factors, patient position, contrast agents, and pharmacologic adjuncts will optimize diagnostic results and patient throughput.

Contrast Media↗
PubMed1978

Sleep, mood, and fatigue during a 14-day He-O2 open-sea saturation dive to 850 fsw with excursions to 950 fsw.

To obtain information on sleep, mood, and performance of divers and surface support personnel during deep dives in the open sea, 12 divers and 12 surface support personnel were monitored during a 14-day open-sea saturation dive using the U.S. Navy Deep Diving System, Mark 2, Mod O. Divers lived in the deck decompression chambers at 850 fsw equivalent and made 5 days of excursion wet dives to approximately 950 fsw via the Personnel Transfer Capsule. Electroencephalographic and self-report measures of sleep, and measures of mood, anxiety, and 4-choice reaction time performance were obtained during a predive base-line period and throughout the dive and decompression. Results suggested that, unless personnel are rotated, there are limitations to the practical duration of very deep open-sea saturation dives caused by the accumulation of sleep debt, fatigue, and loss of psychological vigor.

Affect↗
PubMed1978

Diving experience and emotional factors related to the psychomotor effects of nitrogen narcosis.

Simple and complex psychomotor performance were tested among 21 Navy divers under normal conditions and during nitrogen narcosis in simulated dives to 170 ft of sea water. Complex psychomotor performance was impaired significantly during narcosis, while simple psychomotor performance remained essentially normal. Differences between baseline scores for complex psychomotor performance (pre- and post-dive combined) and scores obtained from the two combined testing sessions administered during narcosis were correlated with official Navy records of diving experience and self-reported moods. None of the diving experience measures was associated significantly with these difference scores. The moods of Fatigue and Happiness were, however, correlated significantly with impairment. These results indicate that, although previous experience with nitrogen narcosis and diving tasks do not mediate the performance effects of nitrogen narcosis, the complex psychomotor effects nitrogen narcosis are related to emotional traits.

Adult↗
PubMed1977

Cyclic AMP in action of antidiuretic hormone: effects of exogenous cyclic AMP and its new analogue.

Exogenous cyclic 3',5'-adenosine monophosphate (cAMP) stimulates the effect of the antidiuretic hormone, vasopressin (VP), only in pharmacologic quantities and results have often been inconsistent. The present study examined the ability of a new analogue, 8-[p-Cl-phenylthio]cyclic 3',5'-adenosine monophosphate (C1-PheS-cAMP) to mimic the effect of VP, both biochemically (protein kinase activation) and functionally (hydrosomatic response of perfused collecting tubules) in mammalian kidney tissue. C1PheS-cAMP was found to be about 100 times as effective as cAMP both biochemically and functionally. The increased effectiveness of C1PheS-cAMP is probably is probably due to a greater permeability across the cell membrane and to the resistance of C1PheS-cAMP to enzymatic degradation, Cyclic AMP phosphodiesterase inhibition was observed with C1PheS-cAMP, but its contribution to overall effect was minor. C1PheS-cAMP was found to be more effective than exogenous vasopressin, an effect probably due primarily to its resistance to catabolism. The results provide further new evidence that cAMP and protein kinase are involved in the cellular action of vasopressin. C1PheS-cAMP proved to be a useful tool in the study of hormone action, especially in steps subsequent to cAMP generation.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1977

Extension of pulmonary O2 tolerance in man at 2 ATA by intermittent O2 exposure.

To study extension of O2 tolerance by interruption of hyperoxic exposure, as compared to previous studies of continuous oxygen exposure, five healthy volunteers were exposed to oxygen at 2 ATA on an intermittent schedule of 20 min breathing O2, alternating with 5 min on a normoxic N2-O2 mixture. The cycle was repeated until symptoms or signs of O2 toxicity caused cessation of the experiment. Tracheal irritation and burning on inspiration occurred after 6-9 "oxygen hours" of exposure and progressed to severe tracheobronchial burning sensation, chest pain, and dyspnea after 11-15 h of O2. Average duration of exposure was 13.7 O2 h, inducing a mean vital capacity decrease of 10.3%. The decrease began soon after onset of symptoms. With intermittent O2 administration, nearly a doubling of the average duration of actual oxygen breathing was required to induce marked vital capacity change (greater than 10%) as compared to the previous studies of continuous O2 exposure. The increased duration of tolerable O2 exposure in man resembles the extension of O2 tolerance known to occur in animals exposed to intermittent hyperoxia.

Adult↗