SEM Serum Research Articles

In Vitro Responses of Human Peripheral Small Arteries in Hypercholesterolemia and Effects of Therapy

Studies in both animals and humans with raised lipid levels have demonstrated abnormalities in vascular function usually manifested by an impairment in endothelium-dependent vasorelaxation. This is believed to be an early event in atheroma formation. There are few data on the effects on vascular function in humans of lowering serum lipids. We conducted a study to investigate the effects of cholesterol reduction on the in vitro function of human peripheral small arteries in middle-aged patients with hypercholesterolemia. Subcutaneous gluteal fat biopsies were taken from 18 hypercholesterolemic (HC) patients (mean +/- SEM serum total cholesterol, 9.7 +/- 0.57 mmol/L) and 16 age- and sex-matched control subjects (mean cholesterol, 4.69 +/- 0.18 mmol/L). Subcutaneous small arteries (internal diameter, < 330 microns) were dissected and mounted on a wire myograph for isometric tension measurements. The HC patients showed impaired relaxation to acetylcholine (10(-9) to 10(-6) mol/L) after preconstriction with the thromboxane A2 analogue U46619 (10(-6) mol/L, mean maximum relaxation, 42.9 +/- 5.4%) compared with control subjects (85.7 +/- 4.0%, P < .00001). Incubation with the nitric oxide substrate L-arginine (3 mmol/L) improved the endothelium-dependent vasorelaxation response to acetylcholine (70.9 +/- 6.0%, P < .01) in patients but not in control subjects. Also, there was a smaller but significant difference in responses to the endothelium-independent agent sodium nitroprusside (10(-9) to 10(-6) mol/L) between the HC group (mean maximum relaxation, 76.9 +/- 6.0%) and the control subjects (89.7 +/- 6%; P < .01). A total of 10 patients had a second gluteal skin biopsy and repeat functional studies after successful cholesterol-lowering therapy after a mean period of 9.9 +/- 4.7 months. A significant reduction in total and LDL cholesterol was achieved (5.29 +/- 0.2 and 3.23 +/- 0.21 mmol/L, respectively; P < .001). This restored vasorelaxation to control values in response to both acetylcholine (mean maximum relaxation, 83.3 +/- 3.8%; P < .0001) and sodium nitroprusside (87.9 +/- 4.8%, P < .01). Although both groups were normotensive, there were significantly higher blood pressures in the HC group compared with control subjects (139 +/- 4.1 versus 123 +/- 3.0 mm Hg systolic, P < .01; 84 +/- 1.3 versus 75 +/- 2.2 mm Hg diastolic, P < .01). There was no difference in initial blood pressures between the entire group of 18 and the 10 patients who had repeat biopsies. The blood pressures fell to control values after cholesterol reduction (129.33 +/- 4.93 mm Hg systolic and 72.33 +/- 2.93 diastolic mm Hg, P < .02 relative to pretreatment values). These results demonstrate abnormalities of both endothelium-dependent and -independent relaxation in human peripheral small arteries that are normalized with effective lipid lowering. The changes in blood pressure may have been secondary to the improvement in vascular function.

Episodic changes of serum procollagen type I carboxy-terminal propeptide levels in fertile and postmenopausal women.

The aim of the present study was to optimize the use of serum procollagen type I carboxy-terminal propeptide (PICP) as a possible marker of postmenopausal-376lted changes of bone metabolism. Postmenopausal (n = 20) and healthy fertile young (n = 4) women were studied after informed consent. The postmenopausal women were subdivided in 4 groups: (1) nontreated; (2) treated with estrogen-progestogen replacement therapy; (3) treated with calcitonin, or (4) with kidney or liver diseases. Blood samples were collected at 15-min time intervals for 4, 6 or 8 h. Serum concentration of PICP was measured by radioimmunoassay, in duplicate at two different dilutions. In postmenopausal women mean +/- SEM serum PICP levels were slightly but nonsignificantly higher than in fertile women. Serum PICP levels in estrogen-progestogen or calcitonin-treated women were significantly lower than in non-treated postmenopausal women. Episodic changes of circulating PICP level were observed in fertile and postmenopausal women. The pulses of serum PICP levels did not show significant differences among the groups of women studied. The present study showed that the measurement of serum PICP levels is a useful marker for investigating the changes of bone metabolism. In particular, low PICP levels in postmenopausal women under steroid hormone or calcitonin treatment in part reflect the changes of bone turnover. The pulses of serum PICP levels during a time interval suggest that collagen metabolism in women undergoes a rapid turnover.

Clinical Evaluation and Serum Concentration of Zuclopenthixol Acetate in Psychotic Asian Patients

Nineteen acutely disturbed psychotic Asian patients were treated with a single intramuscular injection of 50 mg of zuclopenthixol acetate in Viscoleo. Patients were assessed clinically before and after treatment using the Brief Psychiatric Rating Scale (BPRS). Serum zuclopenthixol and the inactive geometric isomer trans(E)-clopenthixol were determined by high-performance liquid chromatography after intramuscular injection. All patients improved, with the BPRS being significantly reduced (p < 0.001) at 72 h after injection. Adverse effects were generally few. The mean +/- SEM serum zuclopenthixol concentrations at 24, 48, and 72 h were 19.9 +/- 2.8, 31.5 +/- 4.5, and 17.8 +/- 2.9 micrograms/L, respectively. trans(E)-Clopenthixol concentrations ranged from negligible to 39.5 micrograms/L. This study confirms that a single intramuscular injection of 50 mg is adequate for managing severely disturbed psychotic patients for the first 3 days. The serum zuclopenthixol concentrations attained in the Asian patients were higher than those reported in Caucasian psychiatric patients. In some patients, a considerable amount of zuclopenthixol had been transformed to trans(E)-clopenthixol.

Insulin-Like Growth Factor I: a Modulator of Erythropoiesis in Uraemic Patients?

Anaemia is a feature almost invariably complicating chronic renal failure. Its pathophysiology is multifactorial but the most important cause is erythropoietin (Epo) deficiency. However, either no relation or even a weakly positive relation generally exists between serum immunoreactive (i) Epo and haematocrit values in uraemic anaemia, whereas in anaemias of non-renal origin the correlation is most often strongly negative. Recent evidence indicates that growth hormone also stimulates erythropoiesis. Moreover, late erythroid progenitor cells (CFU-E) require insulin and/or insulin-like growth factor I (IGF-I) for development in vitro. IGF-I has been shown to have a synergistic action with Epo. We have measured serum iEpo and IGF-I levels in 17 haemodialysis patients with severe hyperparathyroidism (mean +/- SEM serum iPTH, 988 +/- 88 pg/ml). Mean age and duration of dialysis treatment were 46.1 +/- 3.4 and 8.8 +/- 1.0 years respectively. Mean haematocrit and haemoglobin values wer 28.1 +/- 1.7% and 9.39 +/- 0.54 g/dl respectively. Mean serum iEpo and IGF-I levels were 20.3 +/- 4.7 mU/ml and 320 +/- 20 ng/ml respectively (normal values for serum iEpo and IGF-I, 17.9 +/- 6 mU/ml and 91 +/- 23 ng/ml respectively). We found that serum IGF-I concentrations were well correlated with haematocrit values (r = 0.68, n = 15, P less than 0.004) whereas serum iEpo values were not (r = 0.41, n = 12, P = 0.18). IGF-I could therefore be an important factor regulating erythropoiesis in uraemic patients, at least when associated with severe hyperparathyroidism.

Circulating estradiol and the activation of male and female copulatory behavior in Japanese quail ( Coturnix japonica)

Previous experiments using systemic and preoptic area (POA) hormone treatments have shown that aromatization of testosterone (T) to estrogen (E) is essential for activation of male-typical copulatory behavior in castrated male Japanese quail ( Coturnix japonica). Two experiments were conducted to determine whether circulating estrogen levels characteristic of normal intact males are high enough to activate male-typical or female-typical copulatory behavior. In Experiment 1, blood samples were drawn every 4 hr from groups of sexually active male quail housed under a 16L:8D light-dark cycle, and assayed for estradiol (E2) concentration. The mean ± SEM serum E2 was 54.2 ± 3.6 pg/ml, and no daily cycle in serum E2 was seen. The males were then tested for sexual behavior; 88% mounted females, and 23% crouched when mounted by males. In Experiment 2, 51 males were castrated and implanted with Silastic tubes containing estradiol benzoate (EB) and/or cholesterol designed to produce five different levels of serum E2, then tested for male- and female-typical copulatory behavior and bled. The serum E2 in EB-implanted quail which mounted (253 ± 30 pg/ml) was significantly higher than that of intact quail in Experiment 1, and only 10.2% of intact males had serum E2 as high as the minimum associated with mounting in EB-implanted males. These results show that serum E2 levels in intact males are not high enough to support male-typical copulation, and that aromatization in the POA to produce locally high E2 levels may be required. In addition, it was found that the threshold serum E2 to elevate receptivity significantly was 3.6 times the intact male level, and only slightly higher than serum E2 reported for intact females. Thus the lack of receptivity in intact males is probably due to insufficient circulating E2, and the male is not defeminized with respect to sensitivity to E2 for activation of receptivity.

Cholesterol Levels and the Breast-feeding Mom

To the Editor.— Additional data are available to help answer a question asked recently in JAMA 1 : Are serum cholesterol levels elevated in lactating women? Mellies et al 2 found mean ± SD levels of plasma cholesterol of 5.6 ± 0.42 mmol/L in 11 women who were breast-feeding 1 month post partum. The quantity had decreased to 4.8 ± 0.27 mmol/L in 6 women who were still breast-feeding after 7 months. There was no correlation between blood and milk cholesterol contents. We obtained the following data in a study on the composition of milks from insulin-dependent diabetic and control mothers in which serum cholesterol levels at 3, 14, and 42 days post partum were measured. 3 At day 3 post partum, the least-squares mean ± SEM serum cholesterol content of the control women was 5.25 ± 0.12 mmol/L (n = 72); day 14, 5.71 ± 0.13 mmol/L (n = 65); and day

Use of an agonistic analog of gonadotropin-releasing hormone (nafarelin) to treat leiomyomas: Assessment by magnetic resonance imaging

The purposes of this study were to investigate the effect of a superactive agonistic analog of gonadotropin-releasing hormone, nafarelin, on uterine leiomyomas and to assess the use of magnetic resonance imaging in monitoring uterine and myoma size. Eleven women with uterine leiomyomas were treated with 800 μg of nafarelin per day for 6 months. Serum gonadotropin and estradiol concentrations were suppressed during treatment. The mean ± SEM serum luteinizing hormone level decreased from 11.1 ± 1.4 to 5.6 ± 0.42 mlU/ml and follicle-stimulating hormone from 9.5 ± 0.66 to 7.5 ± 0.72 mlU/ml by 3 months of treatment (p < 0.01). The estradiol level decreased from a pretreatment follicular phase mean ± SEM of 43 ± 8.3 to 19.8 ± 3.1 (p < 0.05) and 14.8 ± 2.2 pg/ml (p < 0.01) at 3 and 6 months of treatment, respectively. Mean pretreatment androgen levels (testosterone, androstenodione, and dehydroepiandrosterone sulfate) were low in these women and did not change significantly during treatment. Ten women had magnetic resonance imaging, which provided excellent resolution of individual uterine myomas. As assessed by magnetic resonance imaging, the largest myoma decreased in size in nine of 10 women; the mean decrease was 46% ± 9%. Uterine volume decreased in all 10 patients; the mean decrease was 57% ± 7%. In several women myomas reenlarged after discontinuance of nafarelin treatment. Posttreatment myomectomy was carried out in four women; there was minimal blood loss and no surgical complications. These data indicate that suppression of ovarian estrogen production with nafarelin is associated with a decrease in uterine myoma size in many women but that myomas may regrow with reinstitution of ovarian function. Magnetic resonance imaging is an excellent method by which to monitor treatment as changes in the size of the uterus, as well as individual myomas, can be assessed. The optimal use of gonadotropin-releasing hormone analogs may be in perimenopausal women or as presurgical treatment to decrease uterine and myoma size to facilitate myomectomy.

Alterations in immunological function in streptozotocin-induced murine diabetes mellitus: Correction by islet cell transplantation

Cell-mediated and humoral immune responses of streptozotocin-induced diabetic mice were evaluated using in vivo and in vitro immunological assays. C57BL 6 mice were rendered diabetic by a single intraperitoneal injection of 125–200 mg/kg of streptozotocin. Immunological studies were performed after the mice were diabetic (mean ± SEM serum glucose 537 ± 14 mg/dl) for a minimum of 4 weeks. Spleen cells from streptozotocin-induced diabetic mice exhibited significantly diminished direct IgM plaque-forming cell (PFC) responses following either in vivo or in vitro immunization with sheep erythrocytes, markedly impaired cytotoxic cell responses following in vivo or in vitro allogeneic stimulation, and diminished blastogenic response to the T-cell mitogens phytohemagglutinin and concanavalin A. In contrast the blastogenic response of diabetic spleen cells to lipopolysaccharide, a B-cell mitogen, was normal. The defects in in vivo PFC responses and in vivo cytotoxic cell responses were corrected by islet cell transplantation, suggesting that the abnormalities in immunological function of streptozotocin-induced diabetic mice are a consequence of the diabetic state and not of direct streptozotocin toxicity to lymphoid cells.

Stimulation of growth hormone (GH) and somatomedin C in idiopathic GH-deficient subjects by intermittent pulsatile administration of synthetic human pancreatic tumor GH-releasing factor.

After initial challenges with vehicle alone and then 10 micrograms/kg human pancreatic tumor GH-releasing factor (hpGRF)-40, six adult subjects who had presented in childhood with idiopathic GH deficiency were given 0.33 micrograms/kg hpGRF-40, iv, every 3 h for 5 days. Serum GH levels were monitored daily for 90 min after the 0800 h doses of 0.33 micrograms/kg hpGRF-40, and serum somatomedin C was measured at 0800 and 2000 h. In addition, plasma levels of cholesterol, high density lipoprotein cholesterol, and triglycerides were measured daily at 0800 h. Three hours after the last 0.33 micrograms/kg dose, all subjects were rechallenged with 10 micrograms/kg hpGRF-40. In response to the initial 10 micrograms/kg challenge with hpGRF-40, and although serum GH levels rose in two of six subjects, the mean maximum GH level achieved was no different from that after treatment with vehicle alone. Within 12 h after initiation of the intermittent administration of hpGRF-40, mean +/- SEM serum somatomedin C had risen by 0.1 +/- 0.05 U/ml, and at the end of the 5-day period, had increased from 0.24 +/- 0.07 to 0.78 +/- 0.32 U/ml. In response to the second challenge with 10 micrograms/kg hpGRF-40, serum GH levels rose in three of the four subjects who initially failed to respond or had a less than 1 ng/ml GH response. The increase in serum GH was greater in one of the two subjects who had responded to the first dose. In addition, unlike the first dose, the mean maximal serum GH level achieved in response to the second 10 micrograms/kg dose of hpGRF-40 was higher than that in response to vehicle (P = 0.031). Although there was no statistically significant change during the 5-day period, in plasma cholesterol, high density lipoprotein cholesterol, or triglycerides, the latter exhibited a trend toward increased levels. Our preliminary data show that 5 days of intermittent hpGRF-40 administration augment GH secretion in some adults with GH deficiency, suggesting that somatotropes are present in idiopathic GH deficiency and may be primed by hpGRF-40. The rise in serum somatomedin C to normal levels after multiple injections of hpGRF-40 is encouraging, since circulating levels of somatomedin C may be more important than the increase in immunoreactive GH levels as an index of response for induction of linear growth. The demonstration of biological effects of hpGRF-40 in all six subjects without any serious adverse effects suggests that hpGRF-40 has promise in the treatment of GH deficiency.

Thyroid hormones and glycosylated hemoglobin (HbA1) in Juvenile Diabetes Mellitus (JDM)

In 60 newly diagnosed children with JDM we measured serum T4, T3, reverse T3 (rT3) and free T4 (FT4) before and serially at 1, 3 and 5 days and up to 6 months during therapy. The mean ± SEM serum T3 before therapy (71 ± 6 ng/dl) was lower (p<.01) compared to day 5 (96 ± 5) and the T3 on day 5 was lower than controls (126 ± 9) but was normal by 1 month. Mean serum rT3 before therapy (60 ± 3 ng/dl) was higher (p<.001) compared to day 5 (38 ± 2), but day 5 did not differ from controls (32 ± 3). FT4 levels were higher (p < .01) than controls and remained unchanged. Serum TSH was normal throughout. Serum T4 was normal and remained unchanged in patients with −HCO3 > 15 mEq/L, but low before therapy when −HCO3 < 15 and increased to normal by day 3. Serum T3 was lower in patients with low −HCO3 before therapy. The elevated rT3 and FT4 were unaffected by low −HCO3. HbAl fell significantly by paired t test (p < .001) during the first 5 days of therapy, and further decreased during the ensuing 3 months (p < .001). HbA1 correlated with rT3 and inversely with T3 during the study period (p < .001). We speculate that the metabolic disturbance in untreated JDM resembles the "Low T3 Syndrome" of starvation. The association of low −HCO3 and low total T4 and T3 but normal TSH and high FT4 suggests an impairment of binding to the serum thyroid binding proteins. Correlation of T3 and rT3 with HbAl may reflect their dependency on the severity of the disease.