Measurement, characterization, and source of somatostatin-like immunoreactivity in human amniotic fluid.

Somatostatin-like immunoreactivity (SLI) is widely distributed in tissues and biological fluids. To determine whether SLI is also present in amniotic fluid, samples obtained by amniocentesis from 30 normal and 27 abnormal pregnancies were studied by radioimmunoassay. Direct incubation of [(125)I-Tyr(1)]tetradecapeptide somatostatin (SRIF) with amniotic fluid resulted in 89% tracer degradation. Damage was reduced to <5% when samples were acidified and boiled before the assay. With this technique, SLI was detectable in all normal amniotic fluid samples; the mean level at 15-20 wk of gestation (320+/-55 pg/ml, n = 15) being 4.5 times higher than the mean at 32-43 wk (70+/-12 pg/ml, n = 15) (P < 0.001). In cases of preeclampsia (n = 6), gestational diabetes (n = 5), anencephaly (n = 1), and meningomyelocele (n = 1), SLI values were in the normal range, but in one juvenile diabetic and one patient with chronic renal failure, SLI was undetectable (<10 pg/ml). In a pair of monochorionic diamniotic twins, SLI levels were very different (33 and 197 pg/ml), which suggests that fetal factors are more important than materno-placental ones in determining amniotic fluid SLI. Serial dilutions of amniotic fluid showed parallelism with standard SRIF. When concentrates of pooled amniotic fluid were chromatographed on Sephadex G-25 columns, all SLI eluted in the void volume ahead of SRIF even after treatment with 8 M urea and dithiothreitol. This "big" SLI incubated in amniotic fluid showed 100% stability over 24 h at 37 degrees C, whereas SRIF was rapidly inactivated (t((1/2)) congruent with 7 min). Extracts of placenta and fetal membranes contained no SLI, but small amounts (6-20% of total amniotic fluid SLI) were found in cells from fresh fluid. Radioimmunoassay of SLI in extracts of seven paired cord arterial and venous plasma samples showed no arteriovenous gradient consistent with fetal origin of cord blood SLI. It is concluded that (a) amniotic fluid contains SLI which is of fetal origin and (b) normal levels vary with gestational age. The SLI has a higher molecular weight (>/=5,000) and is more stable in amniotic fluid than SRIF.

Evidence for somatostatin precursors in human stomach, placenta, and amniotic fluid.

Human stomach, placenta, and amniotic fluid have previously been shown to contain immunoreactive somatostatin (IRS). The present studies were undertaken to further characterize this IRS. Gel chromatography of amniotic fluid revealed only one peak of somatostatin-like immunoreactivity (SLI; mol wt, 15,000) regardless of gestational age. Extracts of human fetal stomach contained three peaks of SLI: 87% of the total IRS coeluted with synthetic tetradecapeptide somatostatin (SRIF), 12% coeluted with synthetic somatostatin-28 (S-28), and 4% coeluted with amniotic fluid SLI. Extracts of 9- to 13-week-old placentas contained 38.9 +/- 5.3 pg IRS/mg protein (range, 21-62 pg IRS/mg protein). Chromatography revealed that 57% of the total IRS coeluted with SRIF, 19% coeluted with S-28, and 23% eluted in a position indicating a molecular weight of 12,000. Serial dilutions of amniotic fluid SLI and material from each peak of stomach and placental SLI showed parallelism with synthetic SRIF. Treatment with 8 M urea and dithiothreitol did not convert any of these SLIs to smaller immunoreactive forms. Incubation of purified amniotic fluid SLI with 1% (wt/wt) L-(tosylamido 2-phenyl)ethyl chloromethyl ketone-trypsin for 90 min resulted in partial conversion to immunoreactive material coeluting with SRIF. When synthetic S-28 was incubated in fresh amniotic fluid at 37 degrees C, it was rapidly degraded (t 1/2 approximately or equal to 25 min). These studies indicate that human amniotic fluid IRS is composed of 15K SLI only, whereas human stomach and placental IRS are heterogeneous, comprising SRIF as well as larger forms of SLI which probably represent SRIF precursors.

Antibodies to insulin, pancreatic polypeptide, glucagon, and somatostatin in insulin-treated diabetics.

The hormonal content of the commercial insulins most commonly used in Canada (Connaught) and the USA (Lilly) was measured, and the prevalence of antibodies to these hormones was determined in the serum of diabetics treated with one of these preparations. Connaught insulins contained 62 +/- 10 ng pancreatic polypeptide (PP)/100 U insulin, 11 +/- 2 ng glucagon/100 U, and 56 +/- 16 pg somatostatin (SRIF)/100 U. Lilly single peak insulins contained 693 +/- 41 pg PP/100 U, 8 +/- 2 ng glucagon/100 U, and 323 +/- 174 pg SRIF/100 U, whereas the recently introduced Lilly improved single peak insulins contained 8 +/- 2 ng PP/100 U, 30 +/- 10 ng glucagon/100 U, and 43 +/- 1 pg SRIF/100 U. Lilly highly purified Iletin II pork insulin contained 1.0 ng PP/100 U, 0.4 ng glucagon/100 U, and 19 pg SRIF/100 U. Of 111 diabetics treated with Connaught insulin, 91% had antibodies to insulin, 51% had antibodies to PP, 14% had antibodies to glucagon, and 6% had antibodies to SRIF. Antibodies to PP were also found in 2 control subjects (n = 30). In patients who had taken Connaught insulin for 10 yr or more, 97% had insulin antibodies, 84% had PP antibodies, 14% had glucagon antibodies, and 11% had SRIF antibodies. Fasting serum GH levels were normal in all patients with SRIF antibodies. Cord blood from two pregnancies in insulin-treated diabetic mothers contained antibodies to the same hormones as maternal production of antibodies to insulin, PP, glucagon, and SRIF. The importance of these antibodies in the pathophysiology of diabetes is discussed.

Fine-needle aspiration biopsy of thyroid nodules. A diagnostic method that minimizes the need for surgery.

Fine-needle aspiration biopsy is the most accurate and cost-effective method of evaluating thyroid nodules. When an experienced endocrinologist and cytopathologist are available, aspiration biopsy is the diagnostic procedure of choice. In our experience at Straub Clinic and Hospital, Honolulu, it has more than halved the number of operations for suspected thyroid cancer.

The effect of thermal preconditioning of the limb on flexor tendon healing.

Thermal preconditioning reduces inflammation by inducing cytoprotective heat shock proteins. We evaluated the role of limb thermal preconditioning in a rabbit model of flexor tendon repair. The treatment groups underwent limb preconditioning by elevating the limb temperature to 41.5 degrees C for 20 minutes. The animals were sacrificed three and six weeks after flexor tendon repair. Heat shock protein72 expression of the treated limb was measured at 18 hours. Macroscopic analysis demonstrated a significant decrease in adhesion formation in the three week treatment group. The inflammatory infiltrate was significantly reduced for both treatment groups. The difference in ultimate tensile strength was not significant. We conclude that thermal preconditioning of the limb before flexor tendon repair decreases inflammation and adhesion formation in a rabbit model and has the potential to improve clinical outcome of flexor tendon surgery.

Pituitary apoplexy. The importance of skull roentgenograms and computerized tomography in diagnosis.

In two patients with pituitary apoplexy, computerized tomograms demonstrated a suprasellar mass that, after infusion with contrast medium, showed a peripheral ring-like enhancement consistent with a pituitary adenoma with central necrosis. In patients with symptoms or signs suggesting subarachnoid hemorrhage or meningitis, the finding of an enlarged sella turcica on plain skull roentgenograms should raise the possibility of pituitary apoplexy. This diagnosis may be rapidly and safely confirmed by computerized tomography.