Plasma cyclic nucleotide levels in juvenile-onset diabetes.

In patients with juvenile-onset diabetes, plasma concentrations of 3',5'-adenosine cyclic monophosphate (cAMP) were significantly lower than those of norman subjects [16 +/- 4 and 24 +/- 7 pmol per milliliter (p less than 0.025), respectively] as determined in this laboratory; whereas there were essentially no differences in plasma levels of 3',5'-guanosine cyclic monophosphate (cGMP). Because cAMP inhibits cell growth and cGMP stimulates it, these findings may represent an important factor in the atherosclerotic and obliterative angiopathies of diabetic individuals. We observed that cyclic nucleotide values were the same whether or not the subjects were receiving insulin. Those given insulin plus enough glucose to maintain hyperglycemia revealed modest elevations in cyclic nucleotide levels. Thus, the ratio of cAMP to cGMP, abnormally low in juvenile-onset diabetes, is relatively independent of short-term variations in plasma levels of either glucose of insulin.

NO-dependent vasorelaxation is impaired after gene transfer of inducible NO-synthase.

Proinflammatory stimuli produce expression of inducible NO-synthase (iNOS) within blood vessels and are associated with impaired endothelium-dependent relaxation. Gene transfer of iNOS was used to test the hypothesis that expression of iNOS in blood vessels produces impairment of NO-dependent relaxation as well as contraction. An adenoviral vector containing cDNA for murine iNOS, AdCMViNOS, and a control virus, AdCMVBglII, were used for gene transfer to rabbit carotid arteries in vitro and in vivo. After gene transfer of iNOS in vitro, contractile responses to KCl, phenylephrine, and U46619 were impaired. Relaxation in response to acetylcholine, ADP, A23187, and nitroprusside was also impaired. For example, maximum relaxation of vessels to acetylcholine (10 micromol/L) was 78+/-4% (mean+/-SE) after AdBglII (10(10.5) plaque-forming units) and 34+/-5% after AdiNOS (10(10.5) plaque-forming units, P<0.05). NO-independent relaxation in response to 8-bromo-cGMP and papaverine was not impaired after AdiNOS. Contraction and relaxation were improved in carotid arteries expressing iNOS by aminoguanidine and L-N-iminoethyl lysine, inhibitors of iNOS. After intraluminal gene transfer of iNOS in vivo, contraction of vessels in vitro was normal, but responses to acetylcholine were impaired. In summary, the major finding is that NO-dependent relaxation is impaired in arteries after gene transfer of iNOS in vitro and in vivo. Thus, expression of iNOS per se impairs NO-dependent relaxation.

Safe Tummy Tuck: Anatomy and Strategy to Avoid Injury to the Lateral Femoral Cutaneous Nerve During Abdominoplasty.

BACKGROUND: Abdominoplasty is one of the most common aesthetic procedures performed in the United States. While poor contour and unsatisfactory cosmetic result have been recognized, neuropathic pain from lateral femoral cutaneous nerve injury has been poorly described. We aim to improve outcomes by using an anatomical study to develop a strategy to avoid injury to the lateral femoral cutaneous nerve in abdominoplasty. METHODS: Twenty-three fresh cadaver abdomens were dissected to evaluate the course of the lateral femoral cutaneous nerve, using 2.5× loupe magnification. Measurements were taken from the nerve to the anterior superior iliac spine and from the pubic symphysis to the lateral femoral cutaneous nerve. Recordings of the relationship of the nerve to the inguinal ligament and depth at scarpa's fascia were also made. Statistical analysis was performed to find average distances with a standard deviation. RESULTS: On average, the distance from the lateral femoral cutaneous nerve to the anterior superior iliac spine was 3.62 (SD = 1.32) cm and 13.58 (SD = 2.41) cm from the pubic symphysis in line with the inguinal ligament. The lateral femoral cutaneous nerve was found at the inguinal ligament 80% of the time and 20% of the time superior to the ligament and always deep to scarpa's fascia. CONCLUSION: Abdominoplasty carries a high patient and surgeon satisfaction rate. The plastic surgeon is continuously challenged to identify ways to improve outcomes, efficiency, and morbidity. Minimal and careful dissection in the area around 4 cm of the anterior superior iliac spine in addition to preserving scarpa's fascia near the inguinal ligament may serve as key strategies to avoiding lateral femoral cutaneous nerve injury.

Cushing's disease: growth hormone response to hypoglycemia after correction of hypercortisolism.

Growth hormone responses to insulin-induced hypoglycemia were studied in 17 patients with inactive Cushing's disease. A normal GH rise was found in 9 of 9 patients without evidence of progressive pituitary tumor after bilateral adrenalectomy and 3 of 4 patients after correction of hypercortisolism by transsphenoidal removal of pituitary microadenomas. In contrast, 3 of 4 patients with Nelson's syndrome had impaired GH responsiveness to hypoglycemia. These results show that GH responsiveness is normal in the majority of patients with inactive Cushing's disease and do not support the concept of a primary hypothalamic or central nervous system abnormality of GH regulation in Cushing's disease.

Pituitary ACTH dependency of nodular adrenal hyperplasia in Cushing's syndrome. Report of two cases and review of the literature.

Cushing's syndrome due to nodular adrenal hyperplasia comprises a clinically and biochemically heterogeneous group of disorders whose pathogenesis is unclear. We describe two patients with atypical steroid dynamics and large unilateral adrenal nodules who had pituitary ACTH-dependent disease. In the differential diagnosis of Cushing's syndrome, we recommend repeated ACTH measurement and selective venous sampling-particularly in those patients with impaired dexamethasone suppressibility and abnormal findings on computerized tomography.

The relationship of nutrition and health to worker productivity in Kenya.

PIP: A correlation study was undertaken in 2 districts of Kenya to ascertain the relationship between nutrition and health of workers and their productivity. 269 road workers were examined. Blood was taken for hematological examination; urine was tested and stools collected for parasitical study; dietary information was collected; and work output studies conducted. The data show evidence of low calorie reserves and undernutrition in a large percentage of the workmen. Hematocrit and hemaglobin levels were inadequate in more than 30% of the men at 1 of the 2 sites, indicating the presence of parasitic infection-induced anemia. Stool samples confirmed these diagnoses. There was a consistent and highly significant relationship between low weight-for-height and low productivity. Dietary intervention was tried in 1 of the 2 following ways: 1) calorie supplementation; or 2) iron supplementation. Body weight increased in the calorie supplementation group and hematocrit levels increased for those receiving iron. It is concluded that the provision of food at the worksite would benefit workers both physically and psychologically. Without such intervention, economic development will be difficult to achieve.^ieng

Evidence that expression of inducible nitric oxide synthase in response to endotoxin is augmented in atherosclerotic rabbits.

Atherosclerotic lesions contain monocytes/macrophages and vascular smooth muscle cells and thus may have an increased capacity for generation of nitric oxide by inducible nitric oxide synthase (NOS). We used three approaches (contractile responses, generation of L-citrulline from L-arginine, and staining with NADPH-diaphorase) to test the hypothesis that after administration of lipopolysaccharide (LPS) in vivo, generation of nitric oxide by inducible NOS is augmented in atherosclerotic arteries. New Zealand White (normal, n = 18) and Watanabe heritable hyperlipidemic (atherosclerotic, n = 21) rabbits were anesthetized and injected intravenously with vehicle or LPS. Contractile responsiveness of aortic segments was examined in vitro 4 hours after injection of LPS in vivo. There was a substantial (approximately fivefold) decrease in contractile sensitivity of aortas from LPS-treated atherosclerotic rabbits and a small (approximately twofold) decrease in normal rabbits. Incubation of aortic segments with aminoguanidine, which inhibits inducible NOS, restored contractile responsiveness after LPS treatment. In vitro assay of conversion of [14C]L-arginine to [14C]L-citrulline by aortic segments demonstrated marked (approximately fivefold) increase in calcium-independent conversion of [14C]L-arginine by LPS-treated atherosclerotic, but not normal, aortas. NADPH-diaphorase staining demonstrated positive cells only in the endothelium of normal rabbits and in the lesions and media of the atherosclerotic aortas in both vehicle- and LPS-treated rabbits. The general distribution of these NADPH-diaphorase-positive cells resembled that of smooth muscle cells and not macrophages. Thus, impairment of contractile responses, generation of L-citrulline, and staining with NADPH-diaphorase suggest that atherosclerotic arteries have increased capacity for generation of nitric oxide by inducible NOS.

Effect of atherosclerosis on responses of the perfused rabbit carotid artery to human platelets.

Vascular responses to intraluminal and abluminal activation of human platelets were examined in carotid arteries from normal and atherosclerotic rabbits. The carotid artery was perfused in vitro, platelets were activated with thrombin (0.1 unit/ml), and changes in diameter were measured. In vessels from normal animals, intraluminal activation of platelets produced dilatation of preconstricted arteries. The dilator response was attenuated by N omega-nitro-L-arginine (10(-5) M), an inhibitor of synthesis of endothelium-derived relaxing factor-nitric oxide (EDRF-NO), and augmented by LY53,857 (10(-5) M), a 5-HT2-serotonergic antagonist. Abluminal activation of platelets produced modest constriction in quiescent arteries, which was inhibited by LY53,857. Intraluminal but not abluminal ADP produced pronounced dilatation of preconstricted arteries. In vessels from atherosclerotic animals, endothelium-dependent dilatation to intraluminal activation of platelets and to ADP was impaired and dilator responses to sodium nitroprusside were normal. These experiments indicate that 1) intraluminal activation of human platelets produces endothelium-dependent dilatation in perfused carotid arteries, whereas abluminal activation of human platelets produces vasoconstriction, which is mediated primarily by serotonin, and 2) atherosclerosis markedly impairs vasodilator responses to activation of human platelets, probably because vasodilatation to ADP released from platelets is impaired.

Interaction of human platelets and leukocytes in modulation of vascular tone.

We tested the hypothesis that the vasodilator response to human platelets is modulated by polymorphonuclear leukocytes (PMNs). Responses to platelets activated with thrombin, as well as PMNs activated with N-formylmethionyl-leucyl-phenylalanine (FMLP), were examined in perfused rabbit carotid arteries in vitro. Activation of platelets produced marked dilatation, and activation of PMNs produced modest constriction in arteries preconstricted with phenylephrine. Vasodilator responses to platelets were greatly impaired during infusion of activated PMNs. Pretreatment of PMNs with superoxide dismutase (SOD) partially restored dilator responses to platelets. Because SOD only partially restored vasodilator responses to platelets, we tested the possibility that adenosine-diphosphatase (ADPase) activity of PMNs may degrade ADP released by platelets and thus reduce vasodilator responses. After incubation with PMNs, dilator responses to ADP, but not acetylcholine, were significantly impaired. These findings indicate that vasodilatation produced by activated human platelets is profoundly impaired by activated leukocytes. We conclude that two mechanisms may account for this effect: 1) endothelium-derived relaxing factor, released in response to platelet-derived ADP, is inactivated by superoxide anion generated by activated PMNs and 2) ADP is degraded by ADPase activity of PMNs. We speculate that platelet-leukocyte interaction may have important effects on vasomotor tone.

Altered vascular responses to platelets from hypercholesterolemic humans.

Activated platelets release potent vasoactive factors. Previous studies have focused on mechanisms by which vascular abnormalities lead to altered responses of atherosclerotic arteries. We tested the hypothesis that the activation of platelets from hypercholesterolemic humans produces abnormal vascular responses. Responses to intraluminal and abluminal activation of platelets from normal subjects and type II hypercholesterolemic patients (total cholesterol, 274 +/- 16 [mean +/- SEM] mg/dl) were examined in carotid arteries from normal rabbits perfused in vitro. Intraluminal activation of normal platelets produced pronounced dilatation of arteries preconstricted with phenylephrine. Vasodilator responses to intraluminal activation of platelets from hypercholesterolemic patients were greatly impaired. Vasodilator responses to platelets from hypercholesterolemic patients were not restored to normal by LY53,857 (10(-5) M), a 5-hydroxytryptamine2-serotonergic antagonist, by SQ29,548 (10(-5) M), a thromboxane A2/prostaglandin H2 receptor antagonist, or by apyrase (1.5 units/ml), an enzyme with ADPase activity. Abluminal activation of normal platelets produced modest constriction in quiescent arteries, and abluminal activation of platelets from hypercholesterolemic patients produced augmented vasoconstrictor responses. The major finding is that vasodilator responses to platelets from hypercholesterolemic patients are profoundly impaired, and vasoconstrictor responses to platelets from hypercholesterolemic patients are augmented. Mechanisms in addition to increased release of serotonin, thromboxane, and ADP appear to contribute to impaired vasodilator responses to hypercholesterolemic platelets. Thus, alteration of platelets by hypercholesterolemia, as well as altered vascular reactivity, may contribute to abnormal vascular responses in atherosclerosis.

Proteinases in cardiac and skeletal muscle.

Although changes in proteolysis in muscle tissue are now well documented for a variety of physiological and pathological conditions, the mechanism of degradation of cellular protein during normal protein turnover remains to be elucidated. Data from several laboratories have suggested the involvement of alkaline serine proteinases. Recent studies have questioned these results, and demonstrated that the serine proteinases are of mast cell origin and are not present in muscle cells. The only proteinases to date that have been shown to be present in muscle cells and capable of degrading myofibrillar proteins are Ca2+-activated proteinase, cathepsin B, and cathepsin D. Recent interest and developing awareness of endogenous enzyme inhibitors in cells may unmask many new enzymes.

Defective acidification of endosomes in Chinese hamster ovary cell mutants "cross-resistant" to toxins and viruses.

Like many physiological ligands, several viruses and toxins enter mammalian cells through receptor-mediated endocytosis. Once internalized, the nucleic acids of several viruses and the toxic subunit of diphtheria toxin gain access to the cytosol of the host cell through an acidic intracellular compartment. In this report, we present evidence that one class of mutants of Chinese hamster ovary (CHO)-K1 cells, which is "cross-resistant" to Pseudomonas exotoxin A, diphtheria toxin, and several animal viruses, has a defect in acidification of the endosome. Cells were allowed to internalize fluorescein isothiocyanate-conjugated dextran before subcellular fractionation. Fluorescence measurements on subcellular fractions permitted measurement of the internal pH of the isolated endosomes and lysosomes. Our results show that (i) endosomes and lysosomes from CHO-K1 cells maintain an acidic pH, (ii) acidification of both endosomes and lysosomes is mediated by a Mg2+/ATP-dependent process, (iii) GTP can satisfy the ATP requirement for acidification of lysosomes but not of endosomes, and (iv) at least one class of mutants that is cross-resistant to toxins and animal viruses has a defect in the ATP-dependent acidification of their endosomes. These studies provide biochemical and genetic evidence that the mechanisms of acidification of endosomes and lysosomes are distinct and that a defect in acidification of endosomes is one biochemical basis for cross-resistance to toxins and viruses.

Cushing's disease. Selective trans-sphenoidal resection of pituitary microadenomas.

We undertook trans-sphenoidal microsurgical pituitary exploration in 20 consecutive patients with Cushing's disease, eight of whom had normal sellar polytomography. Pituitary adenomas were selectively resected in 17 and histologically confirmed in 14. In one patient total hypophysectomy revealed a 1.5-mm basophilic adenoma, and in two patients vascular anomalies prevented sellar exploration. Hypercortisolism was corrected in 17 patients (i.e., in 16 of the 17 undergoing selective tumor removal and in the one with total hypophysectomy). Panhypopituitarism occurred only in this patient, and transient diabetes insipidus occurred in five. Most patients became glucocorticoid deficient and required replacement therapy. We conclude that pituitary tumors are present in the great majority of patient with Cushing's disease, even in the absence of demonstrable tomographic changes in the sella turcica, and that selective removal corrects hypercortisolism with little morbidity.