Search PubMed⌕ Search

Biomedical subjects

A J Davidson

Publications and source records attributed to A J Davidson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Expression of murine interleukin 11 and its receptor alpha-chain in adult and embryonic tissues.

Interleukin 11 (IL-11) is a multifunctional cytokine that has diverse effects on blood cells and their precursors and on a number of cell types outside of the hematopoietic system. The cDNAs encoding murine IL-11 and its receptor alpha-chain (IL-11R alpha) have recently been isolated. We have used the RNase protection assay to examine the expression of murine IL-11 and IL-11R alpha in a range of adult mouse tissues, in embryos, and during development of embryonic stem (ES) cells into cystic embryoid bodies in vitro. The testis showed a high level of IL-11 gene expression while a much lower level of expression was detected in the lung, stomach, small intestine, and large intestine. Expression of IL-11 was not detected between day 10.5 and day 18.5 post coitum of embryonic development or in differentiating ES cells in vitro. In contrast, the IL-11R alpha was found to be expressed in all adult tissues examined, during embryonic development, and in totipotent and differentiating ES cells.

Animals↗
PubMed1997

Radiologic assessment of renal masses: implications for patient care.

The relationships between the gross pathologic features of neoplastic and nonneoplastic renal masses and their radiologic analogues, described above, establish specific guidelines for the influence of radiologic studies on clinical management. A tumor that contains fat, as determined with CT or MR imaging, can be confidently diagnosed as an angiomyolipoma without further diagnostic intervention. The size of the lesion should be used to influence clinical decisions related to the fact that angiomyolipomas larger than 4 cm in diameter are more apt to hemorrhage than those smaller than that size. High confidence can also be assigned to those renal masses that exhibit the radiologic analogues for hemangioma with use of imaging modalities that document their vascular nature. These findings should be sufficient for therapeutic decisions directed toward embolization or surgical excision when clinically warranted. If a mass can be characterized as a simple cyst by satisfying all of the required CT or sonographic criteria, no further diagnostic interventions are required. This includes the radiologic findings of thin rim of peripheral calcification and thin septa with or without calcification. An equally high level of confidence is associated with the broad range of CT, sonographic, or MR imaging findings that indicate malignant tumor. These militate for radical surgery. However, the same findings are also encountered in hemorrhagic and infected renal cyst, abscess, benign neoplasms, and inflammatory mass. Therefore, surgical excision, the nature of which will vary according to individual circumstances, is usually required to establish these diagnoses. Exceptions to the need for a tissue diagnosis might be considered in the patient in whom a renal mass is detected in the clinical setting of infection and in the patient with either a small asymptomatic renal mass or a small hyperattenuating mass that meets the other criteria of a simple cyst. Here again, individual circumstances may lead to such alternatives as aspiration of the mass for culture, interval follow-up to seek evidence of growth, or dismissal.

Abscess↗
PubMed1996

Finding the medically underserved: a need to revise the federal definition.

The relationship between the primary service area (PSA) of an urban community health center (CHC) program and a federally defined "medically underserved area" (MUA) was assessed. Federal guidelines that most reliably predicted medical underservice were identified. The service area was statistically defined by census tract penetration rates. The MUA was defined by an index of medical underservice (IMU) according to federal parameters of physician supply, poverty level, percentage elderly persons, and infant mortality. An index score was calculated for the country, service area, and each census tract. Analysis by tract determined the most significant discriminating parameters. By excluding two tracts concentrated with managed-care physicians, the service area qualified as an MUA. Tracts that fulfilled MUA and service area criteria were highly associated (p < 0.0001). Only poverty level and infant mortality were useful discriminating parameters. Federal indicators of demand (elderly population) and supply (physicians) did not adequately address issues to access for the medically underserved in urban neighborhoods. Other parameters that might serve as proxies of care access and underserved are discussed.

Aged↗
PubMed1995

Differences in participation in experimental drug trials among persons with AIDS.

To measure participation in experimental drug trials among persons with acquired immunodeficiency syndrome (AIDS), we interviewed 4,604 persons at least 18 years of age who were reported to have AIDS to 11 state and city health departments in the United States. Ten percent reported that they were currently in a trial. Current enrollment differed significantly (p < 0.05) by race/ethnicity (blacks, 5%; whites, 14%; Hispanics, 15%), gender (women, 7%; men, 11%), exposure mode (injection drug use, 5%, men who have sex with men, 14%), annual household income (< $10,000, 8%, > or = $10,000, 14%), education (< 12 years, 6%; > or = 12 years, 12%), health care (no regular care, 1%, public care, 8%; private care, 17%), and time since AIDS diagnosis (< or = 6 months, 9%; > 6 months, 12%). Adjusting for all factors and time since AIDS diagnosis, blacks (adjusted odds ratio [AOR] = 0.35, 95% confidence interval [CI] 0.26, 0.47), persons with less than 12 years of education (AOR = 0.71, CI 0.53, 0.96), and those without regular health care (AOR = 0.24, CI 0.10, 0.61) remained less likely to be in a trial. Blacks, those with less than 12 years of education, and persons without regular health care were less likely than other persons with AIDS to be currently enrolled in AIDS trials. To increase enrollment of these persons, researchers must address barriers to participation for these groups.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Multilocular cystic renal tumor in children: radiologic-pathologic correlation.

Multilocular cystic renal tumor is a term that encompasses two histologically distinct but grossly indistinguishable lesions: cystic nephroma and cystic partially differentiated nephroblastoma (CPDN). Cystic nephroma is a segmental, purely cystic mass characterized by multiple septations composed entirely of differentiated tissues, without blastemal elements. CPDN is also a multiloculated lesion without nodular solid components, but its septa contain embryonal cells. Multilocular cystic tumors primarily affect boys during early childhood, with a substantial number of the lesions containing blastema (CPDN), and adult women, with lesions that more commonly lack septal blastema (cystic) nephroma). As a rule, nephrectomy is curative and the clinical course benign, but CPDN may recur locally. Although cystic nephroma and CPDN cannot be distinguished radiologically, failure to do so has no practical impact on management, since all of these tumors are surgically removed. However, the differential diagnosis includes other pediatric cystic renal masses that may require different treatment stratagems: Wilms tumor with cyst formation due to hemorrhage and necrosis, cystic clear cell sarcoma, cystic mesoblastic nephroma, cystic renal cell carcinoma, multicystic dysplastic kidney, and segmental multicystic dysplasia in a duplicated renal collecting system.

Adolescent↗
PubMed1995

Renal medullary carcinoma associated with sickle cell trait: radiologic findings.

PURPOSE: To correlate the radiologic and pathologic findings in patients with renal medullary carcinoma and sickle cell trait. MATERIALS AND METHODS: Radiologic studies of five pathologically proved cases of renal medullary carcinoma were retrospectively correlated with gross pathologic findings. Excretory urograms, computed tomographic (CT) scans, sonograms, photographs of the gross surgical specimens, and an angiogram were available for review. Each case was analyzed for tumor location, pattern of growth, contrast enhancement and echotexture, angiographic pattern, and stage. RESULTS: All tumors arose centrally within the kidney, grew in an infiltrative pattern, and invaded the renal sinus. Caliectasis without pelviectasis was present in three cases. Contrast enhancement and echotexture were heterogeneous in all patients. Tumor necrosis with communication into the collecting system occurred in one patient. The one available angiogram demonstrated hypovascularity. CONCLUSION: Patients with renal medullary carcinoma share particular demographic, clinical, and radiologic features that might enable radiologists to suggest a specific diagnosis.

Adolescent↗
PubMed1995

HIV testing patterns: where, why, and when were persons with AIDS tested for HIV?

OBJECTIVE: To describe the location of, primary reason for, and time between the first positive HIV test and AIDS diagnosis in a sample of persons with newly diagnosed AIDS. DESIGN: Interviews supplementing information routinely collected through AIDS case reporting. SETTING: Eleven US states and cities. PATIENTS: Persons with AIDS (2441) diagnosed between January 1990 and December 1992. MAIN OUTCOME MEASURES: Location of first positive HIV test, primary reason for testing, and time interval between first positive HIV test and AIDS diagnosis. RESULTS: Overall, persons were tested late in their course of HIV infection: 36% were tested for HIV within 2 months and 51% within 1 year of their AIDS diagnosis. Sixty-five per cent were HIV-tested in acute health-care settings: 33% in hospitals, 28% in physicians' offices, and 4% in emergency departments. Testing during hospitalization was most common among injecting drug users (43%) and persons infected through heterosexual contact (50%). Persons primarily sought HIV testing because of illness (58%); other reasons included being in a known risk group (13%) and having had a known HIV-infected sex partner (8%). Testing because of being in a known risk group was least common among persons infected through heterosexual contact (1%). Among persons in these exposure categories, testing differed by race/ethnicity. CONCLUSION: Most persons with AIDS were tested relatively late in their course of HIV infection, in acute health-care settings, and because of illness. Not knowing one's serostatus precludes early medical intervention and may increase transmission.

AIDS Serodiagnosis↗
PubMed1995

Who are the primary caretakers of children born to HIV-infected mothers? Results from a multistate surveillance project.

OBJECTIVE: To determine the primary caretakers of children born to women with human immunodeficiency virus (HIV) infection. METHODS: We interviewed women at least 18 years of age who have been reported with HIV infection or acquired immunodeficiency syndrome to local health departments in 10 cities and states regarding the primary caretaker of their children born since 1977. RESULTS: Of 541 HIV-infected women who had been pregnant since 1977, 88% had living children. These women comprised 478 family units (mother and children); 234 (49%) of these units consisted of two or more children. The most common primary caretakers for all children within a family unit were the mother alone (46%), grandparents (16%), and both mother and father (15%). When the mother used injection drugs or lived alone, in a shelter, or with friends, almost one quarter of all children were cared for by their grandparents. Only 30% of the mothers knew about child care assistance services, and only 8% had contacted or used these services. CONCLUSIONS: Mothers with HIV, often alone, are the primary caretakers of their children. Increased provisions for child care assistance and planning for future permanent placement of orphaned children are urgently needed.

Adult↗
PubMed1994

Acute pyelonephritis: can we agree on terminology?

There is no general agreement on which terms to use to report abnormalities on imaging studies in patients with kidney infection. The Society of Uroradiology recommends a simplified nomenclature that is based on the traditional and widely understood term acute pyelonephritis. To provide a framework for the simplified terminology, the authors review the relevant pathophysiology with its imaging correlates and offer a historic perspective on the terminology issues.

Acute Disease↗
PubMed1993

Cost of care for patients with human immunodeficiency virus infection. Patterns of utilization and charges in a public health care system.

BACKGROUND: The increasing impact of human immunodeficiency virus (HIV) infection on the health care delivery system requires surveillance of current patterns of HIV-related health care utilization to adequately plan for future needs. Most studies to date have concentrated on inpatient care for patients with the acquired immunodeficiency syndrome (AIDS). Outpatient utilization has been less well studied and there are few data regarding HIV-infected patients without a diagnosis of AIDS. METHODS: Denver Health and Hospitals is a public system delivering comprehensive health care to mostly indigent residents of the city and county of Denver. Patients with HIV infection in this system were identified through multiple surveillance sources, and billing system records for these patients were analyzed. RESULTS: During 1990, 812 patients with HIV infection of 13 years or more were accessed in the Denver Health and Hospitals. During that year, the total HIV-related health care charges were $7,858,690, of which 57% were for inpatient care and 43% for ambulatory care. Patients with AIDS (34% of patients) accounted for 62% of all charges, and patients with HIV infection but without a diagnosis of AIDS (66% of patients) for 38% of charges. Compared with national predictions, patients with AIDS in our system had lower inpatient and higher outpatient utilization. CONCLUSIONS: These results are consistent with a shift from inpatient to outpatient health care services in patients with AIDS. A significant proportion of HIV-related health care costs are incurred by patients who have not yet developed AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Renal oncocytoma and carcinoma: failure of differentiation with CT.

The authors studied the hypothesis that oncocytoma and adenocarcinoma of the kidney can be differentiated with computed tomographic (CT) criteria and that differences would become more apparent as tumors enlarged. On contrast material-enhanced scans, homogeneous attenuation throughout the tumor and a central, sharply marginated, stellate area of low attenuation were considered predictors of oncocytoma. Any area of decreased attenuation in the tumor except for a stellate, central area was used as a predictor of adenocarcinoma. Among oncocytomas larger than 3 cm in diameter, 67% exhibited the criteria for oncocytoma and 33% met the criterion for adenocarcinoma; among smaller oncocytomas, the respective results were 82% and 18%. Among adenocarcinomas larger than 3 cm in diameter, 84% fulfilled the criterion for malignancy and 16% were incorrectly predicted to be oncocytomas; among smaller adenocarcinomas, the respective results were 58% and 42%. The authors conclude that the CT criteria used are poor predictors of the diagnosis of oncocytoma or adenocarcinoma regardless of tumor size.

Adenoma↗
PubMed1992

Persistent hypermethioninaemia with dominant inheritance.

A clinically benign form of persistent hypermethioninaemia with probable dominant inheritance was demonstrated in three generations of one family. Plasma methionine concentrations were between 87 and 475 mumol/L (normal mean 26 mumol/L; range 10-40 mumol/L); urinary methionine and homocystine concentrations were normal. Plasma homocystine, cystathionine, cystine and tyrosine were virtually normal. The concentrations in serum and urine of metabolites formed by the methionine transamination pathway were normal or moderately elevated. Methionine loading of two affected family members revealed a diminished ability to catabolize methionine, but the activities of methionine adenosyltransferase and cystathionine beta-synthase were not decreased in fibroblasts from four affected family members. Fibroblast methylenetetrahydrofolate reductase activity and its inhibition by S-adenosylmethionine were also normal, indicating normal regulation of N5-methyltetrahydrofolate-dependent homocysteine remethylation. Serum folate concentrations were not increased. The findings in this family differ from those previously described for known defects of methionine degradation. Since the hepatic and fibroblast isoenzymes of methionine adenosyltransferase differ in their genetic control, this family's biochemical findings appear consistent with a mutation in the structural gene for the hepatic methionine adenosyltransferase isoenzyme.

Amino Acid Metabolism, Inborn Errors↗
PubMed1992

Barrier contraceptives and sexually transmitted diseases in women: a comparison of female-dependent methods and condoms.

INTRODUCTION: Most efforts at sexually transmitted disease (STD) protection center on condom use, but little is known about how condoms compare with other barrier methods, particularly those controlled by women. METHODS: To evaluate the effect of different barrier contraceptives on the prevalence of STDs and other vaginal infections, we retrospectively studied 5681 visits by women to an urban STD clinic. RESULTS: As compared with women using no contraceptive or with tubal ligations, women using the contraceptive sponge or diaphragm had at least 65% lower rates of infection with Neisseria gonorrhoeae and Trichomonas vaginalis, while condom users had 34% and 30% lower rates, respectively. For Chlamydia trachomatis, the reduction was 13% among sponge users, 72% among diaphragm users, and 3% among condom users, although these differences were not significant. When compared with women using condoms, women using female-dependent methods (sponge or diaphragm) had significantly lower rates of both gonorrhea and trichomoniasis. Vaginal candidiasis was more common among women using diaphragms but not other barrier methods, while rates of bacterial vaginosis were similar among all groups. CONCLUSIONS: Women using the contraceptive sponge or diaphragm experience protection from STDs to a greater extent than those relying on condoms. Female-dependent barrier contraceptives should receive more attention in STD risk-reduction programs.

Adult↗
PubMed1991

Characterization of risk factors for Helicobacter pylori infection among men attending a sexually transmitted disease clinic: lack of evidence for sexual transmission.

The mechanism of transmission of Helicobacter pylori is unknown. To investigate the role of sexual behavior and demographic factors in the acquisition of H. pylori infection, we evaluated the seroprevalence of antibody to H. pylori in 370 men attending an urban sexually transmitted diseases clinic. Sera from the following three groups were analyzed by enzyme-linked immunosorbent assay for H. pylori-specific immunoglobulin G: 78 human immunodeficiency virus (HIV)-seropositive homosexual men, 102 HIV-seronegative homosexual men, and 190 HIV-seronegative heterosexual men. Overall, the seroprevalence of H. pylori was 100 of 370 men (27%), with rates of 18% in HIV-seropositive homosexual men and 20% in HIV-seronegative homosexual men versus 35% in heterosexual men (P less than 0.005, chi 2 test). By ethnic group, 21 (12%) of 181 Caucasian men, 40 (41%) of 97 black men, and 37 (43%) of 87 Hispanic men were seropositive (P less than 0.001, chi 2 test). Multivariate analysis revealed that race was associated with H. pylori seropositivity independent of HIV status, sexual preference, or age. There was no relationship between H. pylori seropositivity and the number of lifetime sexual partners or previous sexually transmitted diseases. Three HIV-seropositive men with H. pylori immunoglobulin G had essentially identical antibody titers over 8 to 16 months of follow-up. In conclusion, black and Hispanic men have significantly higher H. pylori seroprevalence rates than do Caucasian men, but neither sexual behavior nor HIV infection influences the presence or persistence of H. pylori antibody. Further evaluation of the factors associated with these ethnic differences may lead to a better understanding of H. pylori acquisition and transmission.

Adolescent↗
PubMed1991

Clear cell sarcoma of the kidney: CT, sonographic, and pathologic correlation.

The sonographic and computed tomographic findings in 12 children aged 1-6 years with clear cell sarcoma of the kidney were reviewed retrospectively. Tumor size, calcification, and internal architecture were characterized and correlated with the gross pathologic findings. All tumors were unilateral and large (8.5-16 cm in diameter). Except for one, all masses were predominantly solid, and all contained some well-defined portions of low attenuation or hypoechogenicity that represented tumor necrosis. In addition, seven tumors contained uncomplicated fluid-filled cysts with diameters ranging from a few millimeters to 5 cm. Extension into the inferior vena cava was not noted. The radiologic features of clear cell sarcoma of the kidney are common to all malignant renal neoplasms. Some cases, however, may have features that simulate those of benign conditions, such as multilocular cystic nephroma or segmental cystic dysplasia. No pattern was discerned that would permit discrimination between clear cell sarcoma of the kidney and the most common renal neoplasm of childhood, Wilms tumor.

Child↗
PubMed1991

Marked elevations of serum alkaline phosphatase in patients with AIDS.

We have observed many patients with AIDS who have unexplained marked elevations in serum alkaline phosphatase. To determine the frequency of alkaline phosphatase elevations in patients with AIDS, and to identify diagnoses, medications, and demographic factors associated with such elevations, we conducted a retrospective study of the first 90 consecutive AIDS cases in hospitals affiliated with the University of Colorado Health Sciences Center in Denver, Colorado. We found elevations of alkaline phosphatase in excess of 1,000 IU/L in 17% of consecutive patients with AIDS. This level of elevation was less frequent in patients with Kaposi's sarcoma but there was otherwise no significant association with diagnoses or medications, or transmission categories for AIDS. The majority of the patients with elevations to this level did not have documented opportunistic infections or biliary tract dilatation previously described in the "cholangitis" syndrome in AIDS patients. Other explanations for these elevations for this common laboratory finding may exist.

Acquired Immunodeficiency Syndrome↗