Endogenous opiates: 1996

This paper is the nineteenth installment of our annual review of research concerning the opiate system. It summarizes papers published during 1996 reporting the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress, tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.     

The contribution of six chronic conditions to the total burden of mobility disability in the Dutch population

OBJECTIVES: This study assessed the proportions of the burden of mobility disability in the Dutch population that are attributable to musculoskeletal diseases, lung diseases, neurological disorders, heart diseases, diabetes, and cancer. METHODS: National survey data were analyzed with an elimination technique that combines the results of logistic regression analysis and the disease prevalence. RESULTS: Of the total prevalence of disability (20.5%), 33.7% can be attributed to these six chronic conditions. Musculoskeletal disorders account for the major part, whereas the contribution of cancer is very small. CONCLUSIONS: The potential benefits of effective curative or preventive treatments for chronic conditions, in terms of reduction of the disability burden in the population, are limited.     

Androgen metabolism and prostate cancer: establishing a model of genetic susceptibility

The prostate is an androgen-regulated organ, which has led to long-standing interest in the role of androgens in prostate carcinogenesis. Although evidence of a hormonal etiology for prostate cancer is strong, it is almost entirely circumstantial. Much of the problem in proving a causal relationship relates to the continued difficulties in reliably measuring human tissue-specific exposure to endogenous steroid hormones. The international and racial-ethnic variations in prostate cancer incidence, combined with the effects of migration on risk patterns, have suggested that whereas environmental factors are likely to be important, genetic factors might also play a central role in determining prostate cancer risk. We are developing a polygenic model of prostate carcinogenesis focused around a series of genes involved in androgen biosynthesis and androgen activation, transport, and metabolism in the prostate. In this developing model, we have initially targeted four genes based on three main criteria: (a) all encode products that play important roles in inducing androgen stimulation in the prostate; (b) all are polymorphic; and (c) all show substantial allelic variation in the polymorphic marker among the racial-ethnic groups of greatest interest in terms of prostate cancer risk. In addition to studying how the polymorphic markers of interest are related to prostate cancer development within and between racial-ethnic groups, we are concurrently evaluating whether genotypic variations correlate in the anticipated direction with biochemical parameters in vitro and in vivo. We summarize the development of this model and the state of knowledge related to each of the genes comprising the current model. We discuss the extent to which the current model can explain demographic variation in prostate cancer risk as well as the potential for future expansion of the model to incorporate environmental risk factors as well as additional genes. The model, when fully developed, can potentially provide a basis for targeting populations for screening interventions and/or preventive strategies aimed at the multigene products or at the genes themselves.     

Determination of gene dosage at the PMP22 and androgen receptor loci by quantitative PCR

Although many genetic diseases are caused by the presence of point mutations in respective genes, an increasing number of diseases are known to be caused by gene copy number changes. We report the development of a rapid and reliable PCR-based method for quantitation of gene copy number with sufficient sensitivity to detect single copy changes without the use of radioactive or fluorescent labeling. The sensitivity of this technique has been demonstrated by the detection of the DNA duplication or deletion occurring in two inherited peripheral neuropathies, Charcot-Marie-Tooth type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP), that are caused by a reciprocal duplication or deletion event on chromosome 17p11.2-12. This method relies on the comparison of the amount of PCR product generated from a potentially duplicated or deleted target sequence with the amount of product generated from a disomic reference gene. The value of this ratio (target PCR product:reference PCR product) indicates whether the target sequence is duplicated, deleted, or unchanged. Using primers from within a duplicated or deleted region (PMP22 gene and EW401) and from within a reference region (NF1 gene), we tested 50 CMT1A, 30 HNPP, and 50 unaffected individuals for the presence of a DNA duplication or deletion. Target:reference ratios of 1.58, 1.02, and 0.56 were detected for the CMT1A, unaffected, and HNPP groups, respectively. Thus, differentiation of the three groups of individuals was on the basis of gene copy number. This technique was successfully used to detect the difference in the X chromosome copy number between males and females (target:reference ratios of 1.1 and 2.3, respectively). This approach to the detection of DNA duplications and deletions is sensitive, accurate, and has potential applications in the quantitation of changes in gene copy number associated with diseases characterized by such chromosomal alterations.     

Toward a song code: evidence for a syllabic representation in the canary brain

The occurrence of clathrin-coated buds on immature granules (IGs) of the regulated secretory pathway suggests that specific transmembrane proteins are sorted into these buds through interaction with cytosolic adaptor proteins. By quantitative immunoelectron microscopy of rat endocrine pancreatic beta cells and exocrine parotid and pancreatic cells, we show for the first time that the mannose 6-phosphate receptors (MPRs) for lysosomal enzyme sorting colocalize with the AP-1 adaptor in clathrin-coated buds on IGs. Furthermore, the concentrations of both MPR and AP-1 decline by approximately 90% as the granules mature. Concomitantly, in exocrine secretory cells lysosomal proenzymes enter and then are sorted out of IGs, just as was previously observed in beta cells (Kuliawat, R., J. Klumperman, T. Ludwig, and P. Arvan. 1997. J. Cell Biol. 137:595-608). The exit of MPRs in AP-1/clathrin-coated buds is selective, indicated by the fact that the membrane protein phogrin is not removed from maturing granules. We have also made the first observation of a soluble N-ethylmaleimide-sensitive factor attachment protein receptor, syntaxin 6, which has been implicated in clathrin-coated vesicle trafficking from the TGN to endosomes (Bock, J.B., J. Klumperman, S. Davanger, and R.H. Scheller. 1997. Mol. Biol. Cell. 8:1261-1271) that enters and then exits the regulated secretory pathway during granule maturation. Thus, we hypothesize that during secretory granule maturation, MPR-ligand complexes and syntaxin 6 are removed from IGs by AP-1/clathrin-coated vesicles, and then delivered to endosomes.     

Nuclear morphometry of the myocardial cells as a diagnostic tool in cases of sudden death due to coronary thrombosis

One general signalling mechanism used to transfer the information delivered by agonists into appropriate intracellular compartments involves the rapid redistribution of ionised calcium throughout the cell, which results in transient elevations of the cytosolic free Ca2+ concentration. Various physiological stimuli increase [Ca2+]i transiently and, thereby, induce cellular responses. However, under pathological conditions, changes of [Ca2+]i are generally more pronounced and sustained. Marked elevations of [Ca2+]i activate hydrolytic enzymes, lead to exaggerated energy expenditure, impair energy production, initiate cytoskeletal degradation, and ultimately result in cell death. Such Ca(2+)-induced cytotoxicity may play a major role in several diseases, including neuropathological conditions such as chronic neurodegenerative diseases and acute neuronal losses (e.g. in stroke).     

How does treatment influence endocrine mechanisms in acute severe heart failure? Effects on cardiac natriuretic peptides, the renin system, neuropeptide Y and catecholamines

Inhibin B is a marker of spermatogenesis and Sertoli cell function. The objective of this study was to evaluate the biologic significance of inhibins in subfertile men and the usefulness of inhibin B for the detection of male reproductive dysfunction. Forty-seven subfertile men were evaluated by semen analysis and clinical examination. In addition to semen analysis and hormone determinations, inhibins A and B (Serotec) in all 47 and inhibin A in 25 of these samples using another kit (Biosource) were measured. Higher inhibin B (median, range: 160.3, 81.8-328.5 pg/mL vs. 94.9, 15.6-389.7 pg/mL, P = 0.024) and lower FSH (P = 0.001) were detected in men with sperm concentrations > or =20 million/mL (n = 9), compared to oligozoospermia (sperm concentration <20 million/mL, n = 38). Inhibin B correlated significantly negatively with FSH, LH, and E2, and patient's age and positively with sperm concentration, testicular volume, and TSH. Multiple regression analysis indicated FSH, LH, E2, TSH, and age as the independent variables for inhibin B with a coefficient of determination (R) of 0.53. Simultaneous measurement of both FSH and inhibin B identified more cases with oligozoospermia than either hormone alone. Taking into account the body mass index, the age of the patient, and the indirect mixed antiglobin reaction (MAR) test result in addition to FSH and inhibin B led to the correct semen classification in 45 out of 47 cases. The simultaneous measurement of FSH and inhibin B, taking into account age, body mass index, and the indirect MAR test result appears accurate in identifying subfertility. Inhibin A is detectable in some subfertile men but its significance is not clear.     

Subacute and reproductive effects in mink from exposure to Fusarium fujikuroi culture material (M-1214) containing known concentrations of moniliformin

Okadaic acid (OA) is a potent inhibitor of PP1 and PP2A serine/threonine phosphatases and an inhibitor of phosphatidylinositol 3'-kinase (PI 3-kinase) recruitment/ activation. Here we report that PI 3-kinase associates with a serine kinase activated by OA. Whole cell phosphorylation studies showed that PI 3-kinase associates with a wortmannin insensitive 76 kDa serine phosphoprotein (pp76) distinct from the p85 subunit of PI 3-kinase. Serine kinase assays demonstrated that pp76 phosphorylation was dependent upon a wortmannin insensitive serine kinase contained within PI 3-kinase/pp76 complexes and that this kinase had different cation requirements than PI 3-kinase serine kinase. Treatment of whole cells with OA lead to a wortmannin-independent 7.6-fold increase in pp76 serine phosphorylation and to a 7-fold rise in pp76 kinase activity. Together, these findings indicate that pp76 is a PI 3-kinase associated phosphoprotein and suggest that pp76 may be a novel PI 3-kinase associated serine kinase that is activated by OA.     

Middle-ear lipoma as a cause of otomastoiditis

We present a case report which describes a rare cause of a common clinical problem; eustachian tube dysfunction. A seven-year-old child presented with a history of chronic draining ears, despite rigorous medical therapy and multiple ventilation tubes. At myringotomy a mass was noted in the middle ear, and she was taken to the operating room for exploration. The patient was found to have a pedunculated lipoma arising from the anterior medial aspect of the middle-ear cleft producing intermittent obstruction of the eustachian tube orifice. This case represents the fourth case of a middle-ear lipoma in the world literature. We present a review of the literature and an exploration of possible aetiologies of this unusual entity in the differential diagnosis of eustachian tube dysfunction.