Comparison of glycoconjugates at the surface of developing type II pneumocytes and Clara cells

Summary The apical surface coat of type II pneumocytes and Clara cells in pre- and post-natal rat lung was examined with lectin histochemical methods. Lectins fromHelix pomatia (HPA), peanut (PNA) andMaclura pomifera (MPA) were conjugated with horseradish peroxidase and used to stain paraffin sections of fixed lung with or without certain pre-treatments. HPA and MPA were observed to react with almost all type II pneumocytes at postnatal day 1. Type II pneumocytes that stained with a sialidase—PNA sequence increased from a few positive cells at postnatal day 5 to many in the adult. It has been reported that the surface coat of type II pneumocytes closely resembles that of Clara cells in its staining with histochemical methods employing cationic dyes or lectins including MPA and PNA. However, staining with HPA, especially after periodic acid oxidation, revealed many type II pneumocytes with strong reactivity but showed only a few Clara cells that were faintly positive. HPA also stained alveolar macrophages. The HPA affinity of macrophages, however, was labile to oxidation with periodic acid or galactose oxidase unlike that of type II pneumocytes. This difference suggests that HPA recognizes more than one type of sugar structure.To whom all correspondence and reprint requests should be addressed.     

Localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats An immunohistochemical study

Summary Immunohistochemical localization of cytochrome P-450 in the colonic mucosa of 3-methylcholanthrene-pretreated and untreated rats was studied by indirect fluorescent antibody staining technique. A polyclonal antibody for cytochrome P-450_MC purified from hepatic microsomes of 3-methylcholanthrene-pretreated rats was used for this experiment. A strong immunofluorescence was found to be localized in the cytoplasm of the surface epithelium of the mucosa in the colon of 3-methylcholanthrene-pretreated rats. A faint immunofluorescence was also observed in the epithelium of untreated rats. 7-Ethoxycoumarin O-deethylase activity of colonic microsomes was significantly enhanced by 3-methylcholanthrene-pretreatment in parallel with an increase in the intensity of immunostaining for cytochrome P-450_MC in Western blotting analysis. This is the first report on the localization of cytochrome P-450 in the colonic mucosa.     

Purification and some properties of cytotoxin produced by Clostridium difficile

The cytotoxin produced by Clostridium difficile was highly purified by using ammonium sulfate fractionation and successive column chromatographies of DEAE-Sephadex A-25, hydroxyapatite, Bio-Gel A-0.5m, Phenyl-Sepharose CL-4B, and Mono Q. The purified cytotoxin gave a single band on conventional and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of dithiothreitol. Its molecular weight was estimated to be 260,000 and 50,000 by gel filtration and sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis in the presence of dithiothreitol, respectively. Thus it was supposed that the toxin consists of 5 subunits having molecular weight of approximately 50,000. It had an isoelectric point of 6.6. The toxin was heat-labile (60 C for 10 min) and inactivated by treatment with trypsin and pronase, or at pH below 4 or over 10. The minimum cytotoxic dose of the cytotoxin against Chinese hamster ovary cells was 3 ng. It was also demonstrated that the toxin is antigenically different from enterotoxin of C. difficile.     

Taq I-generated HLA-DQ αpolymorphism in Japanese patients with narcolepsy

Taq I-generated HLA-DQrestriction fragment length polymorphism was examined in Japanese patients with narcolepsy. All patients were DR2 positive and shared a 6.0 kb fragment, although this fragment was found only in 54 % of the healthy DR2-positive Japanese. This finding added the DQ gene to the list of candidates for the possible narcolepsy-susceptibility gene. In contrast, there was no complete association between narcolepsy and DXrestriction fragment length polymorphism. These findings suggest that a narcolepsy-susceptibility gene is located closer to the DQ locus than to the DX locus.     

An assessment of nasal functions in control of breathing

Breathing pattern and steady-state CO2 ventilatory response during mouth breathing were compared with those during nose breathing in nine healthy adults. In addition, the effect of warming and humidification of the inspired air on the ventilatory response was observed during breathing through a mouthpiece. We found the following. 1) Dead space and airway resistance were significantly greater during nose than during mouth breathing. 2) The slope of CO2 ventilatory responses did not differ appreciably during the two types of breathing, but CO2 occlusion pressure response was significantly enhanced during nose breathing. 3) Inhalation of warm and humid air through a mouthpiece significantly depressed CO2 ventilation and occlusion pressure responses. These results fit our observation that end-tidal PCO2 was significantly higher during nose than during mouth breathing. It is suggested that a loss of nasal functions, such as during nasal obstruction, may result in lowering of CO2, fostering apneic spells during sleep.     

Somatomedin-C in the kidney of streptozotocin diabetic rats

To evaluate the possible role of somatomedin-C, insulin-like growth factor I, in renal hypertrophy in early diabetes, kidney tissue SmC concentrations were measured in streptozotocin-induced (80 mg/kg ip) diabetic rats. Body weight, liver weight, plasma SmC concentration, and SmC concentration in the liver of diabetic rats were significantly lower than those of controls. Seven days after induction of diabetes, the kidney weight (898 +/- 95 mg) in diabetic rats was significantly greater than that in controls (755 +/- 69 mg), while SmC concentration in the kidney of diabetic rats (1.7 +/- 0.3 U/g kidney) was significantly lower than that of control rats (5.4 +/- 0.6 U/g kidney). These results suggest that renal SmC may not have an important role in renal hypertrophy in early stages of diabetes and that renal production of SmC may be impaired by insulin deficiency in rats.     

Structural and functional features of cis-acting sequences in the basic replicon of plasmid ColIb-P9.

We have structurally and functionally analyzed the cis-elements essential for ColIb-P9 plasmid DNA replication. The putative oriV region encompassed a region of 172 base pairs (bp) located 152 bp downstream of the repZ gene. A typical dnaA box found in this region proved nonessential for the DNA replication of ColIb-P9. The ssi signal of ColIb-P9 is a homologue of the G-sites of R1 and R100 plasmids. Deletion of the G-site led to 1.5-fold reduction of the copy number, suggesting that although this G-site is not essential, it is important for efficient ColIb-P9 DNA replication. In addition, the ColIb-P9 replicon is highly and extensively homologous with the P307 (RepFIC) replicon, and highly homologous with the R100 (RepFIIA) replicon around the G-site region. These facts imply a common ancestry from which the plasmids have evolved.     

Optimal seasonal timing of univoltine and bivoltine insects

This study examines the optimal seasonal timing of the life cycle for univoltine and bivoltine insects, assuming that resource availability has a peak in the middle of a year and is symmetric around it. Results show that if the growth rate increases in proporrion to the bodyweight, bivoltine life cannot be optimal. If the growth rate is a power function of the bodyweight with a power smaller than unity, a symmetric bivoltine solution can be the optimal provided that the resource availability has a plateau in the middle of the season. If the resource availability has a sharp peak, the optimal pattern is an asymmetric bivoltine solution in which the larval periods of two generations differ in length. The bivoltine life cycle is more likely to be superior to the univoltine one if: growth is fast, suitable growing season is long, biomass loss during nonlarval stages is small, and egg size is small.