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Biomedical subjects

S Bohrer

Publications and source records attributed to S Bohrer.

8 recordsLinked to original sources
PubMed2006

Characterization of the NIST seaweed Standard Reference Material.

The National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) for seaweed was developed through an interlaboratory comparison with 24 participants from 16 countries. After evaluating different techniques to calculate certified values for the radionuclides, the median method was found to be the most representative technique. The certified values were provided for 13 radionuclides and information values were given for 15 more radionuclides. Results for the natural decay series showed disequilibrium in both the uranium and thorium series.

International Cooperation↗
PubMed2000

Ovarian hyperthecosis in the setting of portal hypertension.

Hepatocellular dysfunction and perturbed portal hemodynamics alter steroid metabolism. Men with liver disease have gynecomastia, although women similarly affected rarely show virilization. We report a 10-yr-old girl with portal hypertension and shunting associated with precocious puberty and ovarian hyperandrogenism. This was one of premature twin girls; neither had clitoromegaly or genital ambiguity. In one child, neonatal respiratory problems led to umbilical vein catheterization with subsequent development of portal hypertension. Pubic hair was first noted at age 6 yr, breasts at 7 yr, and severe acne and clitoromegaly at 10 yr. Baseline sex hormones were elevated: androstenedione (A), 413 ng/dL; testosterone (T), 226 ng/dL; and estradiol (E2), 160 pg/mL. Liver transaminases were within the normal range, however, the coagulation profile was mildly abnormal. Cosyntropin adrenal stimulation revealed no steroidogenic defect. Dexamethasone suppression reduced A and T slightly. LH-releasing hormone stimulation produced a pubertal rise in LH and FSH. Pelvic sonography showed a large right ovary with numerous follicles. Surgical exploration revealed symmetrically enlarged ovaries with dense capsules. Histology of ovarian wedge resections showed hyperthecosis; immunohistochemistry showed stromal cells expressing steroidogenic enzymes and proteins. One month postoperatively, A and T were unchanged from baseline, whereas E2 decreased to 56 pg/mL. A single dose of depot leuprolide acetate significantly reduced T. Subsequent treatment with oral contraceptives reduced T to 50 ng/dL, and cyclical menses occurred. We conclude that precocious puberty and ovarian hyperthecosis were induced in this young girl by elevated circulating levels of sex hormones, a consequence of portasystemic shunting and impaired hepatic steroid metabolism.

Androstenedione↗
PubMed1991

Inverse perspective mapping simplifies optical flow computation and obstacle detection.

We present a scheme for obstacle detection from optical flow which is based on strategies of biological information processing. Optical flow is established by a local "voting" (non-maximum suppression) over the outputs of correlation-type motion detectors similar to those found in the fly visual system. The computational theory of obstacle detection is discussed in terms of space-variances of the motion field. An efficient mechanism for the detection of disturbances in the expected motion field is based on "inverse perspective mapping", i.e., a coordinate transform or retinotopic mapping applied to the image. It turns out that besides obstacle detection, inverse perspective mapping has additional advantages for regularizing optical flow algorithms. Psychophysical evidence for body-scaled obstacle detection and related neurophysiological results are discussed.

Algorithms↗
PubMed1987

Indium 111 labeled white blood cell scintigraphy for the diagnosis of upper abdominal abscesses in a child with Wiscott-Aldrich syndrome.

We report on a case of multiple hepatic abscesses in an immunodeficient patient where initial radiologic evaluation by ultrasonography and computed tomography confused early management by failing to demonstrate the abscesses and by suggesting other diagnoses. Indium 111 (In-111) white blood cell (WBC) scanning with Tc-99 liver-spleen scan subtraction accurately demonstrated subcapsular hepatic abscesses in four out of four sequential studies, and later confirmed resolution of the abscesses. We suggest that In-111 WBC scanning may be used as a highly specific method of diagnosing suspected upper abdominal abscesses in children.

Child↗
PubMed1987

The efficacy of computed tomography in evaluating abdominal injuries in children with major head trauma.

Physical examination may be unreliable in the evaluation of children with blunt abdominal trauma particularly in those with associated major head injuries. In the absence of obvious clinical signs or physical findings of intraabdominal injury, the usefulness of abdominal computed tomography in children is controversial. To test the efficacy of CT scans, a 12-month prospective study of computed tomography for the initial assessment of children with blunt abdominal trauma and major head injuries was carried out. Of 320 pediatric trauma admissions to our regional trauma center, 65 consecutive patients with Glasgow Coma Scores less than ten were managed with sequential head and abdominal computed tomography in the emergency room for (1) closed head injury and (2) suspected abdominal trauma. Fifteen patients (23%) were found to have significant intraabdominal injury. Only two required operative intervention. No patients died as a result of the abdominal injuries. In children with significant head trauma and suspected abdominal trauma, combined head and abdominal CT proved to be reliable.

Abdominal Injuries↗