Postnatal alveolar development of the rabbit.

Previous studies of alveolarization have used rats or lambs; however, neither closely reflects human alveolar development. We characterized alveolar development in rabbits (n = 3-7 /group) at 28 days gestation (dg) to 9 mo to determine whether they followed the human pattern more closely. The right lung was made up of 30% alveolar and 50% duct space at 28 dg to 3 days and of 50 and 30%, respectively, at 14 days to 9 mo. Tissue fraction and alveolar wall thickness decreased by 40% 28 dg to birth. At birth, approximately 4.5% of the number of alveoli seen at 9 mo were present, with alveolar number increasing progressively well into adulthood. The rate of alveolar formation was high around birth, decreasing progressively with age. Alveolar volume increased more than twofold (28 dg to birth) and continued to increase postnatally to 16 wk. Surface fraction decreased by 17% (28 dg to 3 days), after which it remained uniform. Our findings suggest that the timing of onset of alveolarization in humans and rabbits is similar and that rabbits may be used to model postnatal influences on alveolar development.     

Ricin-binding properties of acid hydrolases from isolated lysosomes implies prior processing by terminal transferases of the trans-Golgi apparatus

Acid hydrolases were isolated from the lysosome fraction of beta-galactosidase-deficient human fibroblasts and from the mannose 6-phosphate containing medium in which they were grown. Nearly half of the total beta-hexosaminidase and beta-glucuronidase from both sources bound to Ricin specifically. Lysosomal beta-hexosaminidase, metabolically labelled with [35S]-methionine, was also fractionated on Ricin-agarose. SDS-PAGE of immunoprecipitates from Ricin-binding and non-binding fractions revealed approximately equivalent amounts of cross-reacting material at the appropriate MW. We interpret these results to mean that acid hydrolases which are segregated to lysosomes are exposed to trans-Golgi processing enzymes to about the same extent as enzymes which are secreted, and that segregation by the Man 6-P receptor occurs after transit through the trans-Golgi compartment.     

Expression of human cation-independent mannose 6-phosphate receptor cDNA in receptor-negative mouse P388D1 cells following gene transfer

We recently reported the cDNA cloning, sequence, and expression of the human cation-independent mannose 6-phosphate receptor (hCI-MPR) (Oshima, A., Nolan, C. M., Kyle, J. W., Grubb, J. H., and Sly, W. S. (1988) J. Biol. Chem. 263, 2553-2562). The sequence of the hCI-MPR was virtually identical to that of the human insulin-like growth factor II receptor cDNA (Morgan, D. O., Edman, J. C., Standring, D. N., Fried, V. A., Smith, M. C., Roth, R. A., and Rutter, W. J. (1987) Nature 329, 301-307). To test the role of the putative bifunctional receptor in intracellular sorting of acid hydrolases, we studied its effect on lysosomal enzyme transport following gene transfer to receptor-negative cells. Receptor-negative mouse P388D1 cells were transfected with a cDNA construct containing the entire coding sequence of hCI-MPR under the control of the mouse metallothionine I promoter. Stable transformants were isolated and characterized. The expressed hCI-MPR was localized in membranes including the plasma membrane, bound mannose 6-phosphate containing ligands, and mediated endocytosis which could be specifically blocked by mannose 6-phosphate. We next measured the effect of the expressed hCI-MPR on intracellular and secreted acid hydrolases. The intracellular activity of the lysosomal marker enzymes beta-glucuronidase and beta-hexosaminidase increased up to 2-fold following transformation. In addition, expression of the receptor greatly reduced the fraction of acid hydrolases secreted. These phenotypic changes in the transformed cell lines support the proposed role of the cation-independent mannose 6-phosphate receptor in intracellular sorting and targeting of lysosomal enzymes.     

New Arsenite-Oxidizing Bacteria Isolated from Australian Gold Mining Environments--Phylogenetic Relationships

Nine novel arsenite-oxidizing bacteria have been isolated from two different gold mine environments in Australia. Four of these organisms grow chemolithoautotrophically with oxygen as the terminal electron acceptor, arsenite as the electron donor, and carbon dioxide-bicarbonate as the sole carbon source. Five heterotrophic arsenite-oxidizing bacteria were also isolated, one of which was found to be both phylogenetically and physiologically identical to the previously described heterotrophic arsenite oxidizer misidentified as Alcaligenes faecalis . The results showed that this strain belongs to the genus Achromobacter . Phylogenetically, the arsenite-oxidizing bacteria fall within two separate subdivisions of the Proteobacteria . Interestingly, the chemolithoautotrophic arsenite oxidizers belong to the f - Proteobacteria , whereas the heterotrophic arsenite oxidizers belong to the g - Proteobacteria .     

A comparison of lipid metabolism in hepatocytes isolated from fed and starved neonatal and adult rats.

1. The utilization of [1-14C]palmitate by hepatocytes prepared from fed and starved neonatal and adult rats has been examined by measuring isotopic incorporation into various products. 2. In cells from fed adult rats the principal products were esters (triglycerides and phospholipids) but ketone bodies were the main metabolic end products in cells from starved adult and fed and starved neonatal rats. Production of triglycerides exceeded that of phospholipids in fed adult cells whereas phospholipid formation always predominated in neonatal cells. 3. The high rate of fatty acid oxidation and hence NADH formation by neonatal cells is reflected by a lower acetoacetate--3-hydroxybutyrate ratio at the earlier stages of incubation of neonatal cells. 4. The addition of glycerol modified quantitatively the products of palmitate metabolism by adult hepatocytes but no such effects were observed with neonatal cells. 5. Compared with adult cells, neonatal hepatocytes showed very low rates of lipogenesis that were only enhanced a little by addition of lactate/pyruvate and did not show any effects of glucose concentration upon incorporation of tritium from 3H2O into lipids.     

Cleavage of human serum transferrin with N-bromosuccinimide.

Human serum transferrin was fragmented by N-bromosuccinimide and reduction-alkylation. It was observed that there were at least two each of tryptophanyl-serine and tryptophanyl-aspartic acid, and one each of tryptophanyl-alanine and tryptophanyl-glutamic acid bonds. The size of fragments detected by polyacrylamide gel electrophoresis ranged from 8,000 to 70,000 daltons. Several of the fragments were isolated in a homogeneous form with respect to molecular weight, but were shown to be mixtures of at least five molecular species each by end group analysis.     

The use of disposable gaas generating kits for the growth of hydrogen-oxidizing bacteria and the determination of hydrogen autotrophy

A simplified procedure for the determination of autotropic growth of hydrogen-oxidizing bacteria has been developed. The method uses commercially available disposable hydrogen and carbon dioxide kits, commonly used in anaerobic bacteriology, to produce a gaseous atmosphre containing by volume approximately 41% hydrogen, 6% carbon dioxide, 11% oxygen and 42% nitrogen. The atmosphere was suitable for the growth of strains assigned to the species Alcaligenes eutrophus, Alcaligenes paradoxus, Paracoccus denitrificans, Pseudomonas facilis, Pseudomonas flava, Pseudomonas palleronii, Pseudomonas saccahrophilia and Rhodococcus sp. (‘Nocardia opaca’). The method can also be used for the screening of hydrogen-oxidizing ability in bacterial isolates, thus eliminating the need for complex gas mixing devices or expensive gas mixtures.     

Personalisierte Medizin – Vision oder Fiktion? Beispiel: Altersdiabetes

Typical civilization diseases, such as type II diabetes, are common, complex in the underlying pathogenic mechanisms, heterogenous in the phenotype and multifactorial due to a wide variety of possible combinations of disease susceptibility or protective genes in different relevant tissues and negative or positive environmental factors. This is in sharp contrast to classical inherited diseases, such as Chorea Huntington, which are often caused by complete loss‐ or gain‐of‐function mutations in a single gene. The causative polymorphisms of susceptibility genes, however, are characterized by relative subtle alterations in the function of the corresponding gene product, which per se do not support the pathogenesis, by high frequency, high expenditure for their identification and rather low predictive value. Consequently, the reliable and early diagnosis of civilization diseases depends on the individual determination of all (or as many as possible) polymorphisms of each susceptibility gene together with the corresponding gene products and the metabolites emerging thereof.     

Acidocalcisomen,Mitosomen und Apicoplasten. Neu entdeckte Zellorganellen

Three new, membrane‐bounded organelles were detected in the last decade. Acidocalcisomes which occur in pro‐ and eukaryotes are acidic and store calcium, and further also phosphate, oxygen, magnesium, zink, sodium, potassium, and iron. Furthermore, they are engaged in osmoregulation, pH‐ and Ca²⁺‐homeostasis. Mitosomes are strongly reduced mitochondria of different parasitic protists, which were previously grouped as primarily mitochondria‐free organisms. Apicoplasts are the strongly reduced plastids of the parasitic apicomplexans (formerly sporozoa). They are a target for the development of new drugs, e.g. against the cause of malaria, Plasmodium.