Mixed connective tissue disease. A clinico-serological study of 17 cases

Mixed connective tissue disease (MCTD) was described as a distinct clinical syndrome in 1972. Since then many cases have been reported in the literature worldwide. In this study we present our experience with a group of 17 Mexican patients with this syndrome, and we analyze their clinical and serological features, as well as the causes of death in these patients. The patients are Mexican mestizos living in Guadalajara and most of them have been followed-up at Hospital General de Occidente for a period of 1–10 years. The female/male ratio was 16:1, and their age ranged from 14–55 years with a mean of 29 years. The disease duration has ranged from 1–17 years, with a mean of 6 years. Among the clinical manifestations we have found a high frequency of lymphadenopathy when compared with published series (13/17 or 76%), and the laboratory findings in our patients included a very high polyclonal increase of gammaglobulins (93%), lymphopenia (76%), direct immunofluorescence speckled nuclear epidermal deposits in skin biopsies (75%) and positive rheumatoid factor (65%). Other clinical and serological features were similar to those reported in other series of patients with MCTD. Six of the 17 patients have died (35%), and in 3 of them (17.5%) the cause of death was due to an infectious disease that suddenly presented, and apparently was not related to a concomitant high dose of steroids or malnutrition in the patients. It seems that in addition to the already well known autoimmune abnormalities that occur in MCTD, there are other features like the presence of lymphadenopathy, the high polyclonal increase of gammaglobulins, and the lymphopenia, that reflect the profound disturbance of the immune system in this syndrome, possibly contributing to the sudden appearance of a severe infectious disease in some of our patients.Abbreviations ANA antinuclear antibody - CIE counterimmunoelectrophoresis - MCTD mixed connective tissue disease - PHA passive hemagglutination - PM polymyositis - RF rheumatoid factor - SLE systemic lupus erythematosus - SS systemic sclerosis (SS)     

Mixing power, external convection, and effectiveness in bioreactors

The phenomena of mixing and mass transfer of substrates to microorganisms greatly affect the biochemical reactions which take place in fermentation processes. The effect that agitation power has on the observable reaction kinetics involved in beer fermentation has been studied in different types of bioreactors, from laboratory to industrial scale. With this aim in mind, an effectiveness factor, eta, is introduced which is defined as the relation between the existing rate of reaction, whichever bioreactor is considered, and the reaction rate in the well-mixed, and therefore presumably homogeneous, bioreactor with no diffusional limits. The limitation to homogeneously supplying nutrient material to the cells produces a decrease in this effectiveness factor, which has been correlated to the energy dissipation rate with a similar slope to that which appears in an existing correlation in the literature between this energy and the mass transfer coefficient. Additionally, a dimensionless reaction-convection number, N(RC), which is a function of the power input per unit volume, is proposed, which has been appropriately employed in correlating the effectiveness factor for the types of processes in which convection may be the key resistance factor. (c) 1996 John Wiley & Sons, Inc.     

An extended x-ray absorption fine structure study of the high-affinity cation-binding site in the purple membrane.

The structure of the high-affinity cation-binding site of bacteriorhodopsin was studied using extended x-ray absorption fine structure techniques. The results obtained for Mn2+ in aqueous solution and for the complex BR-Mn2+ (1:1 molar ratio) show great similarities, suggesting that Mn2+, when bound to this site, is coordinated with six atoms of oxygen, forming an octahedral disposition. The interatomic distance between the atoms of oxygen and the Mn2+ was found to be 2.17 A for the complex BR-Mn2+, similar to Mn2+ in solution (2.15 A). In addition, the absence of any other peak at greater distances in the Fourier-transformed spectrum indicates that neither phosphorus nor sulphur atoms are present in the second coordination shell. This suggests that this binding site is located in the protein, discarding the proximity of lipid polar headgroups.     

A comparative study of the purity, enzyme activity, and inactivation by hydrogen peroxide of commercially available horseradish peroxidase isoenzymes A and C

Horseradish peroxidase (HRP) is a commercially important enzyme that is available from a number of supply houses in a variety of grades of purity and isoenzymic combinations. The present article describes a comparative study made on nine HRP preparations. Six of these samples were predominantly composed of basic HRP, pl 8.5, and three of acidic HRP, pl 3.5. Two of the basic preparations were of lower purity than the others. The apparent molar catalytic activity of basic HRP with 0.5 mMABTS and 0.2 mM H(2)O(2) was around 950 s(-1) (about 770 s(-1) for the less pure samples) and with a 5 mM guaiacol and 0.6 mM H(2)O(2) was about 180 s(-1) for all the samples. A similar value (approximately 1000 s(-1)) was observed for acidic HRP but only at higher concentrations of ABTS (20 mM). With 20 mM guaiacol the molar catalytic activity of the acid isoenzyme was 65 s(-1). The apparent K(M) for ABTS of the acidic isoenzyme was 4 mM whereas for the basic isoenzyme it was 0.1 mM. All the enzymes were inactivated by H(2)O(2) when it was supplied as the only substrate. Under these conditions the partition ratio (r = number of catalytic cycles given by the enzyme before its inactivation), apparent dissociation constant (K(l)), and apparent rate constant of inactivation (k(inact)) were about twice as large for the acidic samples (1350, 2.6 mM, 9 . 10(-3) s(-1)) as for the basic (650, 1.3 mM, 5 . 10(-3) s(-1)). The apparent catalytic constant (k(cat)) was 3-4 times larger, and the efficiency of catalysis (k(cat)/K(l)) was double for the acidic isoenzyme, but the efficiency of inactivation (k(inact)/K(l)) was similar. The data obtained provide useful information for those using HRP isoenzymes for biotechnological applications (e.g., biosensors, bioreactors, or assays). (c) 1996 John Wiley & Sons, Inc.     

Inorganic self-organisation in precambrian cherts

Silica biomorphs are inorganic self-organized precipitates resulting from a crystal aggregation process controlled by a metal silicate membrane. They display morphological and symmetric properties of living organisms and form under physico-chemical conditions similar to some geochemical conditions suggested for the chemical precipitation of Precambrian chert precursors. In consequence, these inorganic precipitates are proposed as an alternative interpretation to be considered when trying to decipher the biogenicity of putative Precambrian microbiotas.     

Metabolic adaptation of renal carbohydrate metabolism. V.In vivo response of rat renal-tubule gluconeogenesis to different diuretics

We have studied the effects of the diuretics mersalyl, furosemide and ethacrynic acid on renal gluconeogenesis in isolated rat-kidney tubules and on the activities of the most important gluconeogenic and glycolytic enzymes in both fed and fasted rats. Mersalyl (15 mg.kg^–1 animal weight) significantly decreased the rate of gluconeogenesis in well-fed rats (68%) as well as in 24 and 48-h fasted ones (33 and 37% respectively). This inhibition occurred when lactate, pyruvate, glycerol or fructose were used as substrates. Ethacrynic acid at a dose of 50 mg.kg^–1 animal weight provoked a transient inhibition of renal glucose production by almost 20% but only in fed rats with lactate as substrate, whereas the same dose of furosemide did not affect this metabolic pathway.Parallel to these changes, mersalyl caused a significant inhibition in the maximum activity of the most important gluconeogenic enzymes, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase and glucose 6-phosphatase, in both fed and fasted rats. Neither ethacrynic acid nor furosemide produced any variations in the activities of these enzymes. The activity of the glycolytic enzymes phosphofructokinase and pyruvate kinase was not modified by these diuretics. Nevertheless, the activity of the thiol-enzyme glyceraldehyde 3-phosphate dehydrogenase was severely inhibited by mersalyl and to a lesser extent by the other diuretics. This inhibition was higher in fasted than fed rats. Hence, we conclude that the inhibitory effect of mersalyl on renal gluconeogenesis is due, at least partly, to a decrease in the flux through the gluconeogenic enzymes. Blood glucose was not modified after diuretic treatment in fed animals whereas mersalyl decreased the levels of blood glucose in 24-h fasted rats. Thein vivo effects of diuretics on gluconeogenesis correlate well with the previously observedin vitro effects, although ethacrynic acid was less potent as an inhibitorin vivo, probably because of its rapid clearance.Abbreviations EDTA ethylenediaminetetraacetic acid - EGTA ethyleneglycolbis (-aminoethylether) N,N,N,N-tetraacetic acid - DTT dithiothreitol - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid - TRIS 2-amino-2-hydroxymethyl-1,3-propanediol Publication No. 166 from Drogas, Tóxicos Ambientales y Metabolismo Celular Research Group, Department of Biochemistry and Molecular Biology, University of Granada, Granada, Spain     

Immunocytochemical identification of photoreceptor proteins in hypothalamic cerebrospinal fluid-contacting neurons of the larval lamprey (Petromyzon marinus)

Antibodies directed against different visual pigment opsins, and an antibody raised against the C terminal of the -subunit of retinal G protein (transducin) labelled cerebrospinal fluid-contacting cells located within the hypothalamus (postoptic commissural nucleus and ventral hypothalamic nucleus) of ammocoete lampreys (Petromyzon marinus). These antibodies also labelled photoreceptor cells within the retina and the pineal and parapineal organs, but no other areas of the brain. Despite considerable behavioural and physiological evidence for the existence of deep brain photoreceptors, numerous studies have failed to identify photoreceptor proteins within the basal brain. The results presented in this paper support our recent results in the lizard Anolis carolinensis, suggesting that a group of cerebrospinal fluid-contacting neurons within the vertebrate brain have a photosensory capacity. We speculate that these cells mediate extraocular and extrapineal photoreception in nonmammalian vertebrates.     

Ontogeny of some endocrine cells of the digestive tract in sea bass (Dicentrarchus labrax): An immunocytochemical study

Serotonin- and ten peptide-immunoreactive (IR) cell types were identified in the digestive tract of sea bass (Dicentrarchus labrax L.) larvae of four morphofunctional phases ranging in age from hatching to 61 days. The sequence of appearance and location of endocrine cells during ontogenetic development of the larvae was determined. The differentiation of endocrine cells followed a distal-proximal gradient in the gut which paralleled the morphofunctional differentiation. Serotonin-IR cells were identified in the last portion of the digestive tract from phase I onwards and in the gastric region from phase III, before these regions were morphofunctionally differentiated; met-enkephalin-IR cells were identified from phase II onwards in both the differentiated rectum and the undifferentiated intestine; cholecystokinin (CCK)- and synthetic human gastrin-34-IR cells were located only in the intestine and first found in the undifferentiated intestine of phase II; human gastrin-17-, peptide YY (PYY)- and neuropeptide Y (NPY)-IR cells appeared in the intestine from phase II and in stomach in phase IV, when it showed gastric glands; pancreatic polypeptide (PP)- and glucagon-IR cells were observed in both intestine and stomach, but insulin- and somatostatin-IR cells only in stomach, from phase III, during which the intestine but not the stomach was differentiated. PP- and PYY-, PP- and glucagon-, and PYY- and glucagon-like immunoreactivities coexisted from their first appearance in some cells of the gut.     

Rye chromosome arm 3RS encodes a homodimeric inhibitor of insect α-amylase

A new inhibitor of insect -amylase, designated RDAI-1, has been purified from rye (Secale cereale L.) endosperm. RDAI-1 is homologous to wheat homodimeric inhibitors. This homology is supported by their similar N-terminal amino-acid sequences, inhibitory activities towards amylases from Tenebrio molitor (Coleoptera) and human saliva, and aggregative properties in gel-filtration chromatography. The gene encoding RDAI-1, IdhaR1, is located on the short arm of chromosome 3R, which is homoeologous with wheat chromosome arms 3BS and 3DS, where the genes for homodimeric inhibitors have been previously mapped.     

Oleate from triacylglycerols is desaturated in cold-induced developing sunflower (Helianthus annuus L.) seeds

For the first time, an active fatty-acid metabolism is indicated for triacylglycerols (TAG) of developing sunflower (Helianthus annuus L.) seeds. When the developing seeds were transferred to low temperature, the total amount of oleate found in TAG decreased as that of linoleate increased, while the contents of total lipids and TAG remained unchanged. These results suggest that oleate from TAG was used for desaturation. This occurred first in microsomal TAG, but after a long cold period it was observed mainly in the oil-body fraction. Thesn-2 position of TAG was preferentially enriched in linoleate. Apparently, more linoleate than necesary for the maintenance of membrane fluidity was synthesized at the expense of TAG oleate.