Cytochemical observations on the transport of horseradish peroxidase in different segments of the nephron

Synopsis Kidney slices from rats injected with horseradish peroxidase (HRP) 5–10 min before sacrifice were fixed with formaldehyde vapour for 4 hr at 37°C and compared with tissue fixed by perfusion or by immersion. Much more of the injected protein was retained in extracellular and vascular spaces of the nephron in vapour-fixed than in perfusion-fixed or immersion-fixed tissue. The extracellular localization of HRP in the lateral intercellular spaces and in the infoldings of the basal cell membranes showed characteristic differences in different segments of the nephron. The high concentration of HRP in the lateral intercellular spaces of the collecting tubules, as well as the early location of small phagosomes containing HRP in the apical, lateral, and basal cell regions suggested that HRP was reabsorbed through the cytoplasm into the intercellular spaces or excreted in the opposite direction. The intercellular spaces in the terminal segments of the proximal tubules also showed high concentrations of HRP which suggests participation of these spaces in protein transport between the lumen and the peritubular capillaries. The extracellular concentration of HRP early after injection was found, by colorimetric assays of homogenates, to be several times higher in the papilla than in the cortex.     

Deciphering archaeological palimpsests with bone micro-fragments from the Lower Magdalenian of El Mirón cave (Cantabria,Spain)

Abstract

Modern excavation techniques aim accurately to recover extant archaeological data. Usually bone micro-fragments are gathered as a result, however, during archaeological analysis these remains are often set apart as indeterminate bones and generally do not contribute to the interpretation of the deposits. How to decipher archaeological palimpsests using these small bone fragments is the aim of this paper. El Mirón Cave, located in northern Iberia, contains a very rich Cantabrian Lower Magdalenian deposit (17–15 uncal ka BP) with high densities of faunal remains and artefacts. Here, we present zooarchaeological, taphonomic and spatial distribution analyses of macromammal finds, including those small bone fragments, accumulated during a series of intensive and repeated human occupations found in the outer vestibule excavation area. Our results show that a broad spectrum of activities was performed there, including meat, marrow and grease processing and waste abandonment. We propose that bone micro-fragments must be considered when addressing human subsistence reconstructions from animal remains, as they represent the leftovers of the chaîne opératoire of animal carcass exploitation. The archaeological implications of their inclusion are extremely valuable, especially when deciphering palimpsests. A multidisciplinary approach to study these small animal remains provides information that otherwise would be missed.     

Facilitation of the diaphragm response to transcranial magnetic stimulation by increases in human respiratory drive.

The human respiratory neural drive has an automatic component (bulbospinal pathway) and a volitional component (corticospinal pathway). The aim of this study was to assess the effects of a hypercapnia-induced increase in the automatic respiratory drive on the function of the diaphragmatic corticospinal pathway as independently as possible of any other influence. Thirteen healthy volunteers breathed room air and then 5 and 7% hyperoxic CO2. Cervical (cms) and transcranial (tms) magnetic stimulations were performed during early inspiration and expiration. Transdiaphragmatic pressure (Pdi) and surface electromyogram of the diaphragm (DiEMG) and of the abductor pollicis brevis (apbEMG) were recorded in response to cms and tms. During inspiration, Pdi,cms was unaffected by CO2, but Pdi,tms increased significantly with 7% CO2. During expiration, Pdi,cms was significantly reduced by CO2, whereas Pdi,tms was preserved. DiEMG,tms latencies decreased significantly during early inspiration and expiration (air vs. 5% CO2 and air vs. 7% CO2). DiEMG,tms amplitude increased significantly in response to early expiration-tms (air vs. 5% CO2 and air vs. 7% CO2) but not in response to early inspiration-tms. DiEMG,cms latencies and amplitudes were not affected by CO2 whereas 7% CO2 significantly increased the apbEMG,cms latency. The apbEMG,tms vs. apbEMG,cms latency difference was unaffected by CO2. In conclusion, increasing the automatic drive to breathe facilitates the response of the diaphragm to tms, during both inspiration and expiration. This could allow the corticospinal drive to breathe to keep the capacity to modulate respiration in conditions under which the automatic respiratory control is stimulated.     

Histidyl-transfer ribonucleic acid synthetase mutants requiring a high internal pool of histidine for growth

Mutants that require histidine due to an altered structural gene for the histidyl-transfer ribonucleic acid synthetase (hisS) have been isolated by a general selection for histidine-requiring strains in which the mutation producing histidine auxotrophy is unlinked to the histidine operon. One of the mutants has been shown to require an abnormally high internal histidine pool for growth owing to an altered synthetase that is unstable at low histidine concentrations. It is difficult to determine accurately the K(m) for histidine of the synthetase enzyme from the mutant because of the instability of the enzyme at limiting histidine concentrations; however, a histidine K(m) value has been estimated that is approximately 100 times higher than the histidine K(m) of the wild-type enzyme. For the mutant strains to achieve the high internal pool of histidine required for growth, all the systems that transport histidine from the growth medium must be functioning to capacity. Amino acids that interfere with histidine transport strongly inhibit the growth of the mutants. The mutants have been useful in providing a selective genetic marker for transductional mapping in the hisS region. The mutants are discussed as representative of a general class of curable mutants that have an altered enzyme with poor affinity for a substrate or coenzyme.     

1-Thio-beta-D-galactofuranosides: synthesis and evaluation as beta-D- galactofuranosidase inhibitors

Beta-D-galactofuranosidase is a good chemotherapeutic target for the design of inhibitors, since beta-D-galactofuranose is a constituent of important parasite glycoconjugates but is not present in the host mammals. With this aim, we have synthesized for the first time alkyl, benzyl and aryl 1-thio-beta-D-galactofuranosides by condensation of penta-O-benzoyl-alpha,beta-D-galactofuranose with the corresponding thiols, in the presence of SnCl4as catalyst. The complete chemical and spectroscopical characterization of these compounds showed that the reaction was stereoselective. Debenzoylation with sodium methoxide afforded the beta-S-galactofuranosides in high yield. The thioglycosides were tested as inhibitors of the beta-D- galactofuranosidase of Penicillium fellutanum, using for the first time 4-nitrophenyl-beta-D-galactofuranoside as chromogenic substrate. The 4- aminophenyl-1-thio-beta-D-galactofuranoside, obtained by catalytic hydrogenation of the nitrophenyl derivative, was the best inhibitor being then an adequate ligand for the preparation of an affinity phase aimed at the isolation of beta-d-galactofuranosidases from different sources. Also the inhibitory activity of d-galactono-1, 4-lactone was shown.      

DNA-binding proteins present in varicella-zoster virus-infected cells.

DNA-binding proteins present in varicella-zoster virus-infected cells were identified by DNA-cellulose chromatography of radioactively labeled cell extracts. Seven virus-specific proteins, ranging in molecular weight from approximately 175,000 to 21,000, showed affinity for single- or double-stranded DNA or both. These proteins include the varicella-zoster virus major capsid protein, a phosphorylated tegument protein, and a 125,000-molecular-weight species which may be analogous to the major DNA-binding protein of herpes simplex virus. We also identified a number of DNA-binding phosphoproteins by these procedures. Finally, protein blot studies were carried out to determine whether these proteins bind preferentially to virus rather than to host cell DNA.