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Biomedical subjects

S D McDonald

Publications and source records attributed to S D McDonald.

7 recordsLinked to original sources
PubMed1979

The malignant potential of the dysgenetic germ cell in Klinefelter's syndrome.

We report two cases of extragonadal germ cell tumors in patients with Klinefelter's syndrome and review the other cases of germ cell tumors reported in this syndrome. Especially in choriocarcinoma, the presence of Klinefelter's syndrome may be overlooked because of the similar clinical presentations and testicular histology. We recommend karyotypes be carried out in patients with germ cell tumors since the dysgenetic gonad of Klinefelter's syndrome may be important in the pathogenesis of these malignancies. Also patients with Klinefelter's syndrome should be followed closely because of their increased risk of development of germ cell tumors.

Adult↗
PubMed1978

Delayed cure of Cushing's disease after transsphenoidal surgery of pituitary microadenomas. Report of two cases.

Transsphenoidal microdissection has been proposed as a preferred means of treating Cushing's disease. This procedure allows the surgeon to remove a pituitary microadenoma and at the same time to preserve normal tissue. Two cases described here were treated by this method. An interesting and important observation was that neither patient appeared to be cured for 2 to 6 weeks after surgery, as assessed by dexamethasone suppression. Later, normal suppressibility occurred and the course of each patient was compatible with cure. Patients treated by this method should not be automatically retreated because of adrenocorticotropic hormone (ACTH) non-suppressibility in the early postoperative period.

Adenoma, Chromophobe↗
PubMedDate not supplied

Glucose-sensitive membrane and infrared absorption spectroscopy for potential use as an implantable glucose sensor.

The applicability of using infrared absorption spectroscopy for an implantable glucose sensor was tested by measuring absorbance at 9.66 microns for glucose in aqueous solution at known concentrations. A commercial Fourier transform infrared spectrometer was used with an attenuated total reflection technique (ATR). Absorbance measurements were reproducible and linearity was excellent (coefficient of correlation: 0.996), in spite of pH and temperature changes over values that span the human physiologic ranges (pH 6.8-7.8, temperature, 32-43 degrees C) and 18-34% decreases in incident infrared energy. The minimum detectable concentration of glucose, however, was 31 mmol/L (560 mg/d) and, to use infrared sources and detectors compatible with an implantable device, an absorbance peak between 1 and 3 microns must be used. To solve the detection sensitivity and wavelength problems, the ATR prism was coated with a hydrophobic liquid membrane. The absorbance of water varied at 2.95 microns in inverse linear proportion to glucose concentration between 2-31 mmol/L (35-560 mg/dL, r = -0.992). Estimated incident infrared energy at 2.95 microns (0.2 micron bandwidth) was low enough to theoretically allow the use of a lithium battery small enough for implantation. These findings support the concept of using infrared absorption spectroscopy for an implantable glucose sensor.

Biosensing Techniques↗