PubMed HealthSearch

Biomedical subjects

S P Baker

Publications and source records attributed to S P Baker.

At least 19 recordsLinked to original sources

Risk factors for breast cancer in women undergoing mammography.

To determine risk factors for carcinoma of the breast, we compared women with cancer on screening and diagnostic mammography with those in whom cancer was not detected. For 39 months, medical histories were collected by mammography technologists on 3492 women having routine screenings or diagnostic mammograms at our institution. Potential risk factors of women with biopsy-proved breast cancer were compared with those in women who had normal findings on mammograms or negative biopsy results (control subjects). Of the 3492 women, 49 had biopsy-proved breast cancer. There were 3361 patients in the control group, including those women with normal findings on mammograms (3294) and those with negative biopsy results (67). Eighty-two women had incomplete questionnaires or were lost to follow up. Nearly all of the patients with breast cancer were postmenopausal compared with 68% of the control subjects. The mean length of lactation for breast cancer patients was significantly less than for control subjects: 5.6 vs 7.5 weeks (p = .015). This was true also for the postmenopausal patients: 8.1 vs 6.1 weeks (p = .041). Postmenopausal breast cancer patients had menstruated significantly more years (p = .016) than the postmenopausal control subjects: 34 vs 31 years, although the mean age at menarche was not different. When corrected for age, there was no significant difference in the total duration of menstruation in the postmenopausal cancer patients compared with the postmenopausal control subjects. Postmenopausal breast cancer patients had a significantly greater (p = .021) average body weight than postmenopausal control subjects: 71.7 vs 66.7 kg, although body weight was the same when all patients were considered. Similar results were found when Quetelet's index for obesity (weight in kg/height in cm2) (p = .004) was calculated for postmenopausal patients: 28 for cancer patients and 26 for control subjects. There was no significant difference in height between the cancer patients and control subjects when all patients or just the postmenopausal patients were considered. History of oral contraceptive use was significantly less common among postmenopausal breast cancer patients than among postmenopausal control subjects: 9% vs 20%. Patients with breast cancer had lower parity than the control subjects. In our series of patients, women in whom breast cancer was detected on mammography lactated less, showed no significant difference in years of menstruation when corrected for age, had a greater average body weight, used oral contraceptives less often, and had fewer children than women in whom no cancer was detected on mammography.

Body Height

Hip fractures among the elderly: factors associated with in-hospital mortality.

Factors associated with mortality were examined for 27,370 hip fracture patients aged 65 years or older in Maryland hospitals, using discharge data for 1979-1988. Variables of interest included sociodemography, principal medical and injury diagnoses, E-code, year, disposition, and hospital. For both white males and white females, the hip fracture rate doubled with each 5-year increment in age. The overall proportion who died during hospitalization was 4.9% (n = 1,339). After multivariate adjustment, there remained a substantially increased risk of death for males. The relative odds (RO) of dying for males versus females were 1.6. Other factors associated with high relative odds of dying during hospitalization included the diagnosis of septicemia (RO = 12.3), pneumonia/influenza (RO = 4.9), and digestive system disorder (RO = 3.6). The RO of dying doubled in the presence of cardiac, neoplastic, or cerebrovascular disease. Patients with diagnoses of nervous system or mental disorder, hypertension, anemia, musculoskeletal system disease, or urinary tract infection were at decreased risk of dying. Results of the study suggest that the prevention or early diagnosis and treatment of serious infections in the elderly patient with a hip fracture remain an important challenge to clinicians.

Black or African American

Risk factors associated with falls and injuries among elderly institutionalized persons.

A case-control study among 184 matched pairs of patients 65 years of age and older was undertaken to identify risk factors associated with falls and injuries in a long-term care facility in Baltimore, Maryland, in 1984-1985. Patients were matched on length of stay. Variables of interest included sociodemography, functional status, medications, and diagnoses. For all levels of care combined, the following factors were associated (p less than or equal to 0.01) with increased falls: being able to walk (relative odds (RO) = 4.0), age 90 years and older (RO = 3.8), a history of falling (RO = 5.0), and taking a vasodilator (RO = 3.0). Among the 184 fallers, the diagnosis of dementia (RO = 7.5) or taking a diuretic (RO = 7.2) was positively associated with injury (p less than or equal to 0.01). In each of the analyses, medications were associated with falls or injuries, suggesting a feasible intervention. The combination of a history of falling, being able to walk, and being 90 years of age or older increased the relative odds to 51.9 and could alert clinicians to identify and monitor high-risk elderly persons in need of preventive measures.

Accidental Falls

Motor vehicle deaths in children: geographic variations.

Motor vehicle-related injury is the leading cause of death in children ages 0-14 years in the United States. Using data from the National Center for Health Statistics and the Fatal Accident Reporting System, specific types of motor vehicle injury death in children were examined for the years 1980-1985 (using NCHS data) and 1985-1986 (using FARS data). Death rates were calculated for each specific category of motor vehicle injury for each state and were then mapped to determine patterns of geographic variation. In general, nontraffic pedestrian death rates and death rates for crashes involving light trucks and/or rollovers were higher in the West, and rates of pedestrian deaths in traffic were highest in the South. Some of the likely contributing factors and possible interventions are discussed.

Accidents, Traffic

Effects of chronic hypoxia during maturation on the negative chronotropic effect of [H+] on the rabbit sino-atrial node.

Previous studies in our laboratory have shown an effect of 12 weeks of hypoxia on the electrophysiology of the heart. This study was designed to determine the effects of hypoxia for shorter periods (1, 2, 3 and 6 weeks) on the neonatal heart as well as the chronotropic effects of [H+] on sino-atrial automaticity. Rabbits (2 days of age) were raised for 1, 2, 3 or 6 weeks in either a normal or hypoxic environment. At the end of 1, 2, 3 or 6 weeks, they were killed and studied using an isolated sino-atrial tissue preparation and standard microelectrode techniques. Measurements of hematocrit, ventricular weight and ventricular total protein were made. Right ventricular hypertrophy appeared at 2 and 3 weeks in the hypoxic hearts. There was no difference in left ventricular weight or total protein between normal and hypoxic groups over the time studied. Both the basal and maximal (isoproterenol stimulated) spontaneous rates decreased with age. The baseline and maximal rates from hypoxic rabbits were significantly less than those from normal rabbits at 3 and 6 weeks (p less than 0.05). The net negative chronotropic effect of elevated [H+] was more pronounced in the hypoxic than the normal preparations at 3 and 6 weeks. In summary, neonates raised in hypoxia for as short a period as 3 weeks show right ventricular hypertrophy and a decrease in sino-atrial automaticity. The net negative chronotropic effect of [H+] is enhanced with development and chronic hypoxia.

Acidosis

Long-term hyperprolactinaemia reduces basal but not androgen-stimulated oestradiol production in small antral follicles of the rat ovary.

Hyperprolactinaemia disrupts fertility in many species, perhaps by inhibiting ovarian follicular steroidogenesis. The present studies measured oestradiol and progesterone secretion from isolated follicles from rats rendered hyperprolactinaemic in one of two ways. Sustained hyperprolactinaemia was induced by transplantation of two donor pituitary grafts under the renal capsule of adult female rats; grafts remained in place for 3 months. Transient hyperprolactinaemia was induced by pseudopregnancy initiated by cervical stimulation. Small antral follicles were isolated from both groups of rats 8-10 days after the previous vaginal oestrous smear and also from a control group of dioestrous female rats. Follicles were incubated for 3 h in the presence or absence of human chorionic gonadotrophin (hCG) or testosterone. Basal and hCG-stimulated oestradiol production were each reduced in follicles from both hyperprolactinaemic groups, relative to follicles from dioestrous control rats. In contrast, in the presence of testosterone, all groups of follicles produced comparable amounts of oestradiol. hCG stimulated comparable progesterone production by follicles from all three treatment groups. Testosterone elicited smaller increases in progesterone accumulation by follicles from all in-vivo groups. Reduced basal and gonadotrophin-stimulated, but not androgen-stimulated, oestradiol accumulation suggests that androgen production rather than aromatase activity in small antral follicles may be impaired by long-term hyperprolactinaemia.

Animals

A comparison of injury death rates in China and the United States, 1986.

BACKGROUND: The importance of injury as a public health problem is not well recognized in many developing countries. Data have recently become available on injury mortality in China. METHOD: We compared Chinese injury data based on a 100 million population segment for 1986 with data for the United States. RESULTS: The age-adjusted death rate from all injuries for China exceeds the rate for the US (69.0 vs 61.3 per 100,000). The US has higher death rates from motor vehicle crashes, fires, and homicide; China has greater mortality from drowning, poisoning, falls, and suicide. Especially noteworthy in China are the high drowning rates among young children and the elderly and the high suicide rates in rural areas among young adults and the elderly. CONCLUSION: Injury is an important public health problem in China, exceeding in many respects the problem in the United States. It is urgent for China to place high priority on injury research and prevention.

Accidents, Traffic

Work-related aviation fatalities in Colorado 1982-1987.

On-the-job deaths related to aviation are the seventh leading cause of fatal occupational injury in the United States. In Colorado, they comprise 37% of all air transport deaths. A review of all occupational aviation-related fatalities in Colorado during 1982-1987 identified 86 deaths. Data sources were death certificates, Workers' Compensation records, and National Transportation Safety Board reports. Of the fatalities, 5 involved commercial air service, 16 were military personnel, and 65 (76%) were associated with general aviation. Non-military occupations included 21 pilots, 5 flight instructors, 4 crop sprayers, and 3 search and rescue workers or firefighters. There were 18 people going to or from work sites. The 15 weather cases, 7 aircraft malfunctions, and 4 power transmission wire strikes were the most significant factors in two-thirds of the crashes of civilian aircraft. Even experienced pilots exercised poor judgement. The prominence of general aviation in work-related aviation fatalities indicates a need for greater attention to the safety of workers whose jobs entail flying.

Accidents, Aviation

Intravenous nitroglycerin-induced heparin resistance: a qualitative antithrombin III abnormality.

An ability of intravenous nitroglycerin to interfere with the anticoagulant properties of intravenous heparin would have profound clinical implications. To investigation nitroglycerin-heparin interactions, the following pilot study was performed. Patients (N = 18) admitted to the coronary care unit with a diagnosis of either acute myocardial infarction or unstable angina were divided into four treatment groups: (1) intravenous nitroglycerin and intravenous heparin; (2) intravenous nitroglycerin alone; (3) intravenous heparin alone; or (4) neither intravenous nitroglycerin nor intravenous heparin. Serial determinations of activated partial thromboplastin time (APTT), serum heparin concentration, antithrombin III (ATIII) antigen (ATA), and ATIII activity (ATC) were obtained over a 72-hour period. Overall, patients receiving intravenous nitroglycerin did not differ significantly from other patients in APTT, heparin dose, heparin concentration, ATA, ATC, or ATA/ATC ratio (ATR). However, patients receiving intravenous nitroglycerin at a rate exceeding 350 micrograms per minute had a lower APTT (p less than 0.05), lower ATC (p = 0.02), higher ATR (p = 0.004), and a larger heparin dose requirement than patients receiving lower infusion rates. ATR correlated directly (r = 0.91; p less than 0.05) and ATC inversely (r = -0.78; p less than 0.05) with the intravenous nitroglycerin dose. Serum heparin concentration did not correlate with the intravenous nitroglycerin dose. Intravenous nitroglycerin-induced heparin resistance occurs at a critical nitroglycerin dose. A nitroglycerin-induced qualitative ATIII abnormality may be the underlying mechanism.

Adult

Effect of acetylethylcholine mustard on muscarinic receptor-coupled attenuation of cAMP formation in intact GH3 cells.

The effects of acetylethylcholine mustard (Aech-M) on the muscarinic receptor coupled adenylate cyclase system of intact GH3 cells were investigated. The concentration of Aech-M and Ach that inhibited specific [3H]N-methylscopolamine binding by 50% was similar for both compounds (9.3 microM for Ach and 10.7 microM for Aech-M). Pretreatment of intact GH3 cells or isolated membranes with 10 to 50 microM Aech-M, followed by washing, reduced the [3H]N-methylscopolamine binding capacity by 60% and 75-77%, respectively, without changing the KD value for the radioligand to the remaining receptors. Both Aech-M and Ach attenuated forskolin (1 microM) stimulated cAMP formation with half-maximal effects (EC50) occurring at 0.84 microM for Ach and 0.24 microM for Aech-M. The maximal inhibition was 70-80% for Ach and 30-40% for Aech-M. However, the dose-response for Aech-M was biphasic such that at high concentrations (greater than 50 microM) there was a reduction in its ability to attenuate cAMP formation. After 3 min incubation with either Ach or Aech-M, the addition of atropine completely reversed their inhibitory effect even though with Aech-M there was a greater than 50% reduction in receptor capacity. Furthermore, over a 12-min incubation, Ach produced a relatively stable 67-76% reduction in cAMP accumulation, whereas with Aech-M the initial attenuation was gradually reduced such that by 10 min of incubation, no effect was observed. Finally, pretreatment with Aech-M resulted in a reduced sensitivity to the action of Ach as the EC50 values for inhibition of cAMP accumulation were increased 7.6- and 13.5-fold, respectively, with little or no change in the maximal response. The data indicate that Aech-M produces a transient agonist effect to attenuate cAMP formation in intact GH3 cells followed by an antagonist action probably after irreversible binding to the receptor.

Acetylcholine

Effect of chronic hypoxia on cardiac beta-adrenergic and muscarinic receptors during maturation.

The effect of hypoxia on cardiac beta-adrenergic and muscarinic receptors during the first 3 weeks of postnatal development was determined in the rabbit. After the first week of postnatal exposure to hypoxia, there was no change in the ventricular content of beta-adrenergic receptors. However, after 2 weeks of hypoxia, there was a 24% decrease in the receptor content of the left ventricle with no change in the right ventricle. At the end of 3 weeks exposure to hypoxia, the receptor content had decreased by 31% and 32% in the right and left ventricle, respectively. In control animals, there was no alteration in the beta-adrenergic receptor content of either ventricle over the 3 week period. In contrast to the beta-adrenergic receptor, there was no hypoxia-associated alteration in the muscarinic receptor content of either ventricle during the 3 weeks of postnatal study. The data suggest that hypoxia during the first 3 weeks of postnatal development in the rabbit induces alterations in the cardiac beta-adrenergic receptor with no effect on the development of the cholinergic muscarinic receptor.

Animals

Children in motor vehicles. Never too young to die.

In a series of 89 children less than 15 years old who were killed as motor vehicle occupants, children under 1 year of age were greatly overrepresented. Only three children were using child restraint systems or seat belts. Eight were traveling on their parents' laps. Head injuries predominated and were most common in the youngest children. Children under age 1 were the most likely to have reached the hospital alive. The high death rate for very young children was not explained by the circumstances of the crashes or by the age distribution of children involved in all crashes.

Accident Prevention

The composition of amniotic fluid in pregnancies complicated by fetal anencephaly or spina bifida.

The concentration of amniotic fluid glucose, total protein, sodium, potassium, calcium, magnesium and phosphate as well as amniotic fluid osmolality were measured in normal second trimester pregnancies and in second trimester pregnancies complecated by fetal anencephaly or spina bifida. Amniotic fluid glucose concentration was low in anencephaly, while phosphate and total protein were high; calcium concentration and osmolality were slightly elevated with spina bifida. The application of these findings to antenatal diagnosis are discussed.

Amniotic Fluid

Indexes of severity: underlying concepts--a reply.

A recent paper on the concepts underlying six indexes of severity that have been proposed for health services research claimed to identify deficiencies in each. A close examination reveals that the criticisms are generally without substance, and that the claim that the indexes "violate some of the principles implied by their formulation" is in error. Most of the objections apparently stem from fundamental confusion concerning the use of such indexes. Two of the indexes in question, the Abbreviated Injury Scale AIS) and the Injury Severity Score (ISS), have been validated and are being used widely both in the United States and elsewhere as the principal descriptors of trauma in motor vehicle crashes. The use of these indexes has contributed significantly to motor vehicle crash research and to the improvements in vehicles and highways that are reducing the trauma resulting from such crashes.

Abstracting and Indexing