Neuronal growth factors and development of respiratory control

Neurotrophic molecules, released by neurons and neural target tissues, play a pivotal role in regulating neuronal development and plasticity. This article reviews recent work demonstrating the pivotal role of two such molecules, brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF), in the growth and maturation of respiratory neurons and the expression of normal ventilatory behavior. Although BDNF and GDNF are structurally dissimilar and signal through wholly distinct receptors, they are both required for development of peripheral chemoafferent neurons that provide hypoxic drive to the brainstem respiratory network. Studies of genetically engineered mice carrying targeted deletions in the genes encoding BDNF and GDNF, as well as genetic linkage analysis in humans, indicate that these trophic molecules may be candidate genes for human developmental disorders of breathing.     

Renal Na-K-ATPase: its role in tubular sodium and potassium transport

Na-K-ATPase, the enzymatic equivalent of the sodium:potassium pump, is found in large amounts in the kidney, and this organ has figured prominently both as a source for the purification of the enzyme and as a target for the study of its properties. Located on the basolateral aspect of tubule cells, renal Na-K-ATPase plays a key role in the active translocation of Na and K across this membrane as well as in the "secondary active" transport of a number of other solutes. The activity of renal Na-K-ATPase varies in parallel with sustained changes in Na or K transport, indicating the participation of this enzyme in the chronic adaptation of the kidney to altered Na reabsorption or K secretory load. Because of its slow turnover, however, the role of Na-K-ATPase in the modulation of acute changes in cation transport is unclear. Several hormones and vanadate influence renal Na-K-ATPase activity, and their importance as potential physiologic regulators of this enzyme is examined. Most of the information on the renal enzyme has been obtained from studies using homogenates or subcellular fractions thereof, but more recently the development of tubule microdissection and microanalytic methods has made possible the study of Na-K-ATPase in single nephron segments. This approach has opened new possibilities for evaluating the role of this enzyme in kidney function by facilitating correlation of enzyme activity with transport events in the same structure and by enabling us to focus the study of Na-K-ATPase on discrete anatomic subdivisions of the functionally heterogeneous nephron.     

Strategy for purification of coagulation factor concentrates

Advances in biotechnology are permitting significant changes in traditional plasma fractionation schemes. Increases in product purity, safety, and recovery are possible, and new products are being developed. Applications of technology to the purification of factor IX, factor X, protein C, antithrombin III, thrombin, and fibrin glue are described.     

Malignant carcinoid of the pancreas: a cytologic, ultrastructural, and immunocytochemical study of a case diagnosed by fine-needle aspiration of a supraclavicular node metastasis

Carcinoid tumor of the pancreas is extremely rare. This article describes the case of a 22-year-old woman who manifested a typical carcinoid syndrome; a definitive diagnosis of a metastatic carcinoid tumor was made from needle aspiration of a supraclavicular lymph node using morphologic, immunocytochemical, and ultrastructural criteria. The carcinoid tumor was subsequently shown to be of pancreatic origin.     

Major histocompatibility complex class I molecules are required for the development of insulitis in non-obese diabetic mice

An early step in the development of autoimmune diabetes is lymphocyte infiltration into the islets of Langerhans of the pancreas, or insulitis. The infiltrate contains both CD4⁺ and CD8⁺ T cells and both are required for progression to diabetes in non-obese diabetic (NOD) mice. It has been thought that the CD4⁺ lymphocytes are the initiators of the disease, the islet invaders, while CD8⁺ cells are the effectors, the islet destroyers. We question this interpretation because NOD mice lacking MHC class I molecules, hence CD8⁺ T cells, do not display even insulitis when expected.     

Somatic symptoms in primary affective disorder. Presence and relationship to the classification of depression

The incidence and severity of somatic symptoms were determined in 132 patients with major depressive disorder and 80 normal controls. The role of somatic symptoms was analyzed in relation to the unipolar-bipolar division, Research Diagnostic Criteria (RDC) subtypes, hypersomnia, and appetite increase. The data suggest that the rate and level of somatic symptoms increased with the severity of depression and age, only appetite loss differentiated unipolar from bipolar patients, and the classic somatic symptoms of depression were present in most RDC subtypes and not exclusively associated with the "endogenous" subtype. Hypersomnia or increased appetite identified two overlapping depressive subgroups; patients in both groups were young and characterized by high interpersonal sensitivity. Hypersomniac depressed patients were less anxious and agitated; patients with increased appetite were more hostile and showed a greater decrease in libido than age-matched and sex-matched patients with neither symptom.     

Thumbprinting Locally Advanced Pancreatic Cancer: Have We Developed the Optimal Staging System?

Annals of Surgical Oncology -