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Biomedical subjects

A J Davidson

Publications and source records attributed to A J Davidson.

At least 19 recordsLinked to original sources
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↗
PubMed1990

Lymphangioma of the retroperitoneum: CT and sonographic characteristic.

The authors retrospectively evaluated radiologic, clinical, and pathologic findings in 19 cases of lymphangioma of the retroperitoneum. The tumors were judged confined to one compartment of the retroperitoneum in 68% of the cases, whereas in 32% of cases the tumor involved more than one compartment. Abdominal radiography depicted the mass in all cases. Excretory urography demonstrated organ displacement without tumor invasion in all cases. Sonography showed multiloculated fluid in 61% of cases and a unicameral mass in 39% of cases. All but one of the multiloculated lymphangiomas had thick septa. Sonography also depicted the fluid as uncomplicated in 56% of cases. The remainder had debris that sometimes layered in the dependent portion of the cyst. Computed tomography (CT) showed a unicameral mass in 57% and a septated mass in 43% of cases. CT also showed thin, smooth walls in 79% and thick, irregular walls in 21% of cases. At CT the fluid contents were found to be homogeneous and of fluid attenuation in 64% and were complex in 36% of cases. The attenuation of fluid in one case was the same as that of retroperitoneal fat. In two cases the mass contained mural calcification. The most characteristic radiologic finding of lymphangioma of the retroperitoneum is an elongated tumor containing uncomplicated fluid with or without septa. Chyle and mural calcification are very uncommon in this location.

Adolescent↗
PubMed1990

Extraadrenal retroperitoneal paraganglioma: clinical, pathologic, and CT findings.

Paragangliomas of the retroperitoneum arise from specialized neural crest cells distributed along the aorta in association with the sympathetic chain. In order to ascertain characteristic CT features of extraadrenal retroperitoneal paragangliomas to differentiate them from other retroperitoneal tumors, 31 discrete tumors and two cases of paragangliomatosis in 28 patients were reviewed retrospectively, and the CT features were correlated with clinical and pathologic findings. There were 16 men and 12 women. Average age was 37 years (range, 11-70 years). Twenty-four patients (86%) had hypertension. Of these, catecholamine levels were elevated in all 18 patients who had biochemical studies. Four patients (14%) had malignant paragangliomas. The discrete tumors were classified by location as suprarenal (26%), renal hilar (32%), or infrarenal (42%). Suprarenal paragangliomas could not be distinguished from the ipsilateral adrenal gland on CT. The average size of functional tumors was smaller (7.0 cm) than that of nonfunctional tumors (12.0 cm), but the sizes of the two groups overlapped. Smaller tumors were more likely to be homogeneous and have well-defined margins than were larger tumors. Our findings indicate that extraadrenal retroperitoneal paragangliomas are functionally active more often than previously reported and that they are readily detected by CT as soft-tissue masses closely associated with the entire length of the abdominal aorta. However, no CT feature was found that was unique for paraganglioma.

Adolescent↗
PubMed1989

Mature teratoma of the retroperitoneum: radiologic, pathologic, and clinical correlation.

The authors retrospectively evaluated radiologic, clinical, and pathologic findings in 23 cases of mature teratoma arising within peri- or pararenal spaces. Radiologic studies--including abdominal radiographs (21 cases), excretory urograms (12 cases), sonograms (17 cases), and computed tomographic (CT) scans (18 cases)--were evaluated for tumor location, mass effect, calcification, fat, tumor invasion, echo pattern, and tissue characteristics. Most patients were female (3.4:1), younger than 6 months (50%), and asymptomatic. Abdominal radiography demonstrated a mass in 95%, calcium in 92%, and fat in 60% of cases in which CT revealed these components. Similarly, sonography showed uncomplicated fluid in 76% and calcium in 50% of cases. Fat was not reliably distinguished from other soft-tissue components on sonograms. The most characteristic radiologic findings of mature teratoma of the retroperitoneum are a complex mass containing a well-circumscribed fluid component of variable volume, adipose tissue and/or sebum in the form of a fat-fluid level, and calcification in either a congealed or linear strand pattern. These findings are better demonstrated by CT than by sonography.

Adolescent↗
PubMed1988

Class-specific antibody response to pneumococcal capsular polysaccharides in men infected with human immunodeficiency virus type 1.

We characterized the effect of infection with human immunodeficiency virus type 1 (HIV) on levels of total immunoglobulins and pneumococcal vaccine-specific immunoglobulins in 28 heterosexual and 25 homosexual men seronegative for HIV; 27 asymptomatic, seropositive homosexual men; and 21 patients with AIDS. Total serum IgG levels were increased in both HIV-seropositive groups compared with the HIV-seronegative men (P less than .001). Total IgM levels, however, were elevated only in the asymptomatic, HIV-seropositive men (P less than .08); total IgA levels were elevated only in the patients with AIDS (P less than .05). Vaccine-specific serum IgG, IgM, and IgA significantly increased over baseline three and six weeks after immunization in all groups (P less than .05). Responses to vaccine among the HIV-seronegative groups were similar but were greater for all antibody classes than were responses among the HIV-seropositive groups (P less than .05).

Acquired Immunodeficiency Syndrome↗
PubMed1988

Retroperitoneal and pelvic hemangiopericytomas: clinical, radiologic, and pathologic correlation.

Seventeen cases of hemangiopericytoma of the retroperitoneum were retrospectively analyzed for demographic, morphologic, and radiologic features. These tumors were found in all age groups (2 months to 72 years) and occurred in similar numbers of male and female patients. The tumors tended to be large (11 were greater than 8 cm), were well encapsulated, and occurred less frequently in the pelvic retroperitoneal space (six cases) than in abdominal retroperitoneum (11 cases). All tumors were bulky enough to displace part of the gastrointestinal tract, with only two being inoperable. The most distinctive radiologic feature was hypervascularity (found on 11 of 11 angiograms). Other nondiscriminating radiologic features included well-defined margins and necrosis, with nondistinctive amorphous calcification identified in one case. Angiographic or computed tomographic demonstration of hypervascularity in a retroperitoneal tumor is more suggestive of hemangiopericytoma than of a liposarcoma or malignant fibrous histiocytoma, two of the more common tumors of this region.

Adolescent↗
PubMed1988

Prenatal diagnosis of sacrococcygeal teratoma: sonographic-pathologic correlation.

The prenatal sonograms of 15 fetuses with sacrococcygeal teratoma were reviewed to determine the sonographic appearance and the role of sonography in the obstetric management. Each tumor appeared as a large mass arising from the fetal rump. The teratomas exhibited three sonographic patterns: nine were mixtures of cystic and solid components in equal proportions, four were predominantly solid with a few scattered anechoic areas, and two were unilocular cystic masses. Calcifications were detected in six cases. There was no correlation between the sonographic appearance and the presence of immature or malignant components. Ultrasonography allowed visualization of an intraabdominal component in six cases and assessment of findings that were of prognostic importance. Prenatal detection and size determination of the external component can play an important role in planning obstetric management because fetuses with a large tumor should be delivered by cesarean section to avoid dystocia and catastrophic hemorrhage during delivery.

Female↗
PubMed1988

Infiltrative renal lesions: CT-sonographic-pathologic correlation.

The CT and sonographic findings in 23 cases of renal lesions in which the abnormality was infiltrative, as opposed to expansile, were analyzed (invasive transitional cell carcinoma [seven], renal lymphoma [six], metastasis to the kidney [three], acute bacterial nephritis [three], mesoblastic nephroma [two], squamous cell carcinoma of the renal pelvis [one], and renal cell carcinoma [one]). CT scans were evaluated for shape and density of the mass, pelvocaliceal displacement, effect on the renal sinus fat, and the presence of perirenal involvement. Sonograms were evaluated for the shape and echogenicity of the mass and for the effect on the renal sinus echoes. Findings of infiltrative growth included poorly defined margins of the mass; trapped, nondisplaced infundibulae; and calices with occasional calicectasis, diminished contrast enhancement, occasional nephrographic striations, replacement of central sinus fat, loss of central sinus echoes, and variable renal parenchymal echogenicity. The reniform shape was usually preserved and was present in 19 of 20 cases with CT and 13 of 15 cases with sonograms. These observations indicate that analyses of the margins, architecture, and effects on the collecting system and renal sinus by the mass are helpful in the diagnosis of those diseases that characteristically infiltrate the kidney.

Acute Disease↗
PubMed1985

Epidemiologic and clinical factors of Chlamydia trachomatis in black, Hispanic and white female adolescents.

Rates of genital infection with Chlamydia trachomatis, Neisseria gonorrhoeae and Trichomonas vaginalis were determined prospectively in 396 sexually active female adolescents from three ethnically different urban teen clinics. The organisms were identified respectively in cultures of specimens from 21%, 7% and 6% of all adolescents; 28%, 16% and 20% of blacks; 23%, 4% and 2% of Hispanics, and 14%, 2% and 1% of whites. C trachomatis was identified in specimens from 27% of pregnant adolescents and from 42% of adolescents who had gonorrhea or trichomoniasis. Of 85 Chlamydia-positive adolescents, 47 (55%) were asymptomatic. Physical findings significantly associated (P <.001) with chlamydial infection were vaginal discharge, cervical inflammation and mucopurulent endocervical discharge. Not significantly associated (P >.05) with Chlamydia were the use of oral contraception or symptoms of lower abdominal pain, vaginal discharge or dysuria. Because in sexually active female adolescents C trachomatis is three times more common than N gonorrhoeae, care givers need to consider routine screening or epidemiologic treatment (or both) for both pathogens.

Adolescent↗
PubMed1983

Renal malignancies with normal excretory urograms.

Four patients with malignant renal masses showed no abnormality on excretory urograms with tomography. Of the four lesions, two were primary renal cell carcinomas, one was a metastatic focus from a contralateral renal cell carcinoma, and one was a metastatic lesion from rectal adenocarcinoma. A normal excretory urogram should not be considered sufficient to exclude a clinically suspected malignant renal mass. In such an instance, diagnostic evaluation should be pursued using a method capable of topographic anatomic display, such as computed tomography or sonography.

Adenocarcinoma↗
PubMed1979

Computed tomography in the evaluation of the suspected carcinomatous prostate.

Twenty-six patients with physical findings suspicious for prostatic cancer were examined by contrast-enhanced computed tomography (CT) of the prostate region prior to prostatic biopsy of resection. Twelve had benign hypertrophy and/or prostatitis and fourteen had adenocarcinoma. Prostatic contour, density, seminal vesicle "angle," extraprostatic soft tissue "mass," and the pelvic fat planes were evaluated. A nodular prostatic contour was found only in patients with adenocarcinoma of the prostate, indicating a role for CT in the diagnosis of this disease. Two patients with benign prostatic disease had extraprostatic soft tissue "masses" identical to those seen in six patients with adenocarcinoma of the prostate, suggesting limited usefulness of CT in staging patients with known tumor.

Adenocarcinoma↗