Differences in erythrocyte phospholipid membrane long-chain polyunsaturated fatty acids and the prevalence of fatty acid desaturase genotype among African Americans and European Americans

Numerous studies have reported an association between genetic variants in fatty acid desaturases (FADS1 and FADS2) and plasma or erythrocyte long chain polyunsaturated fatty acid (PUFA) levels. Increased levels of n-6 PUFAs have been associated with inflammation and several chronic diseases, including diabetes and cancer. We hypothesized that genetic variants of FADS that more efficiently convert precursor n-6 PUFA to arachidonic acid (AA) may explain the higher burden of chronic diseases observed in African Americans. To test this hypothesis, we measured the level of n-6 and n-3 PUFAs in erythrocyte membrane phospholipids and genotyped the rs174537 FADS variants associated with higher AA conversion among African American and European American populations. We included data from 1,733 individuals who participated in the Tennessee Colorectal Polyp Study, a large colonoscopy-based case-control study. Erythrocyte membrane PUFA percentages were measured using gas chromatography. Generalized linear models were used to estimate association of race and genotype on erythrocyte phospholipid membrane PUFA levels while controlling for self-reported dietary intake. We found that African Americans have higher levels of AA and a higher prevalence of GG allele compared to whites, 81% vs 43%, respectively. Homozygous GG genotype was negatively associated with precursor PUFAs (linoleic [LA], di-homo-γ-linolenic [DGLA]), positively associated with both product PUFA (AA, docosahexaenoic acid [DHA]), product to precursor ratio (AA to DGLA), an indirect measure of FADs efficiency and increased urinary isoprostane F2 (F2-IsoP) and isoprostane F3 (F3-IsoP), markers of oxidative stress. Increased consumption of n-6 PUFA and LA resulting in increased AA and subsequent inflammation may be fueling increased prevalence of chronic diseases especially in African descent.

Longitudinal dynamics of herd-level Mycobacterium bovis MLVA type surveillance in cattle in Northern Ireland 2003-2016

Investigating genetically-structured diversity in pathogen populations over time is important to better understand disease maintenance and spread. Herd-level surveillance of Mycobacterium bovis genotypes (multi-locus VNTR analysis types, MLVA types) from all culture-confirmed bovine tuberculosis (TB) herd cases was undertaken in Northern Ireland (NI), generating an unparalleled, longitudinal, population-level 14-year survey for this pathogen. Across this population, 295 genetically-distinct M. bovis MLVA types were identified in the 19,717 M. bovis isolates surveyed. Of these, the most frequent was MLVA type 002 (23.0%); 151 MLVA types were represented more than once, in groups ranging from 2 to 4438 isolates. Only 23 MLVA types were isolated in all 14 years. Investigating inter-annual frequency of M. bovis MLVA types, examples of statistically-significant expansions (MLVA types 002, 004, 006, 009 and 027), contractions (MLVA types 001, 007 and 011) and maintenance (MLVA types 003 and 005) were disclosed, during a period of fluctuating bovine TB herd-level incidence at the NI scale. The fixed period frequency distribution of MLVA types remained highly right-skewed. Novel VNTR copy number variant MLVA types (N = 242; an average of 17 per annum) were identified throughout the survey. The MLVA type distribution in the landscape was not random; MLVA types showed statistically-significant geographical localization and strong spatial associations with Divisional Veterinary Office (DVO) regions. There was also evidence of differential risk of particular MLVA types across breeds (Holstein/Friesian vs. other), age-class, and sex and some evidence of an association between the number of animals testing positive for bovine TB during the disclosing test and particular MLVA types, although there was substantial variation.

Patient indicators of a pulmonary exacerbation: preliminary reports from school aged children map onto those of adults

BACKGROUND

Despite the importance of identifying and managing a pulmonary exacerbation, and its use as an outcome measure in interventions, there is no standardised definition in cystic fibrosis. In achieving standardised criteria it is important to identify patient-reported indicators.

METHODS

Interviews were undertaken with 35 school aged children. They reported symptoms experienced during a pulmonary exacerbation in two ways: the first symptoms they become aware of, and how they recognised when they were improving. Interviews were taped, transcribed verbatim and the data analysed thematically.

RESULTS

For many children, the onset of an exacerbation was characterised by 'cold' symptoms, tiredness, and changes in cough. For those with moderate or severe disease, sleep disruption, activity induced breathlessness, changes in mood, sputum volume and lack of appetite were common. When describing improvement children focused initially on activities they were now able to perform accompanied by improvements in tiredness and cough. Those with moderate or severe disease also reported improvements in sleep and mood, breathlessness, sputum volume and colour.

CONCLUSIONS

Child-reported indicators of a pulmonary exacerbation tend to map onto those reported by adults. These results provide the rationale for the development of a single scale for school age children and adults that could be sensitive to progressive stages of CF disease.

Increased aortic atherosclerotic plaque development in female apolipoprotein E-null mice is associated with elevated thromboxane A2 and decreased prostacyclin production

The production of thromboxane A(2) (TXA(2)) and prostacyclin (prostaglandin I(2), PGI(2)) is known to be increased in patients with atherosclerosis. In this study, we evaluated the influence of gender on TXA(2) and PGI(2) production, and their association with the progression of atherosclerosis in apolipoprotein E-null (ApoE(-/-)) mice maintained on a high fat diet for 3 months. En face analyses of aortas showed marked increases in plaque formation in female ApoE(-/-) mice. Quantification of the hematoxylin/eosin (H&E) stained cross sections of the aortic arch revealed 3 to 4-fold higher plaque thickness in female ApoE(-/-) mice. Analyses of 24-hours urine samples for 11-dehydro TXB(2) and 2, 3-dinor-6-keto PGF(1a) indicated that female ApoE(-/-) mice produce up to 15-fold more TXA(2) and 50% less PGI(2) than the age matched males. Interestingly, the serum cholesterol levels in ApoE(-/-) females were 20% lower than males on the high fat regimen. No gender-associated changes in the number of T lymphocytes, mast cells and macrophages were evident in the lesion areas of ApoE(-/-) mice. The results suggest that the markedly elevated TXA(2) production and reduced PGI(2) production are gender-related proatherogenic risk factors in female ApoE(-/-) mice.

What defines a pulmonary exacerbation? The perceptions of adults with cystic fibrosis

BACKGROUND

There is no standardised definition of a pulmonary exacerbation in cystic fibrosis (CF). In attempting to achieve standardised criteria it is important to identify patient-reported indicators.

METHODS

Interviews were undertaken with 47 adults with CF. Participants were asked to report symptoms experienced during a pulmonary exacerbation in two ways: the first symptoms they become aware of, and how they subsequently recognised when they were improving.

RESULTS

A range of systemic and respiratory symptoms were reported. Their relative importance varied by severity of disease. The severity and subsequent improvement of an exacerbation was often described as limitations on their activities.

CONCLUSION

These preliminary data suggest that patient-reported indicators of a pulmonary exacerbation may not be the same for all adults with CF. Whether different indicators are associated with specific demographic or clinical variables remains to be evaluated.

Urine PGE-M to assess prostaglandin E2 (PGE2) levels in non-small cell lung cancer (NSCLC)

e19026

Background: COX-2 is often overexpressed in NSCLC leading to high systemic PGE2 levels that in turn play a role in NSCLC pathogenesis. Changes in urine PGE-M (the major PGE2 metabolite) reflect changes in systemic & intratumoral PGE2 [Csiki et al. Clin Cancer Res 11:6634, 2005]. A ≥70% decline in PGE-M in NSCLC patients (pts) treated with celecoxib (C) (400 mg bid) + docetaxel (D) was associated with an apparent survival benefit [Ibid]. To effect maximum COX-2 inhibition we tested a higher C dose in a subsequent phase II trial. Methods: Eligibility: previously treated NSCLC, PS 0–2, evaluable/measurable disease, adequate marrow, renal & hepatic function, no current NSAID or sulfa allergy. Urine PGE-M measured prior to & 5–10 days after C 600 mg PO bid. Pts with ≥70% decline in PGE-M continued on C + D 75 mg/m2 or pemetrexed 500 mg/m2 q3wk x 4 cycles followed by maintenance C 400 mg PO bid until PD or drug intolerance. Results: 21 pts enrolled; F=7, M=14; 2 ineligible (1 carcinoid; 1 elevated LFT); 2 stopped C early (1 ARF; 1 pruritus). Mean PGE-M levels decreased from 38.9 to 7.8 ng/mg Cr pre- & post-C (mean change = 80%; P=0.002). The mean decline was greater in current & former smokers (81%; P=0.002) compared to never smokers (46%; P=0.19). Males had higher pre- treatment PGE-M (44 vs. 28.8 ng/mg Cr; P=0.21). Males had a significant decrease in mean PGE-M levels after C (78%; P=0.011); a similar albeit not significant change occurred in females (P=0.12). 12 screened pts (57%) had a ≥70% decline in PGE-M & received treatment with C + chemotherapy; 8 pts are evaluable for response; SD = 6; PD = 2. Treatment was well tolerated with no cardiac toxicities noted. Conclusions: These preliminary data indicate C 600 mg bid effectively inhibits intratumoral COX-2 in >50% NSCLC pts, a higher percentage than our previous trial using C 400 mg bid. The effect is greatest in former & current smokers & males compared to never smokers & females. Toxicities are acceptable. Accrual is ongoing. [Funding: VICC Lung Cancer SPORE CA90949].

No significant financial relationships to disclose.

A survey of management and economic impact of weeds in dryland cotton cropping systems of subtropical Australia

In dryland cotton cropping systems, the main weeds and effectiveness of management practices were identified, and the economic impact of weeds was estimated using information collected in a postal and a field survey of Southern Queensland and northern New South Wales. Forty-eight completed questionnaires were returned, and 32 paddocks were monitored in early and late summer for weed species and density. The main problem weeds were bladder ketmia (Hibiscus trionum), common sowthistle (Sonchus oleraceus), barnyard grasses (Echinochloa spp.), liverseed grass (Urochloa panicoides) and black bindweed (Fallopia convolvulus), but the relative importance of these differed with crops, fallows and crop rotations. The weed flora was diverse with 54 genera identified in the field survey. Control of weed growth in rotational crops and fallows depended largely on herbicides, particularly glyphosate in fallow and atrazine in sorghum, although effective control was not consistently achieved. Weed control in dryland cotton involved numerous combinations of selective herbicides, several non-selective herbicides, inter-row cultivation and some manual chipping. Despite this, residual weeds were found at 38–59% of initial densities in about 3-quarters of the survey paddocks. The on-farm financial costs of weeds ranged from $148 to 224/ha.year depending on the rotation, resulting in an estimated annual economic cost of $19.6 million. The approach of managing weed populations across the whole cropping system needs wider adoption to reduce the weed pressure in dryland cotton and the economic impact of weeds in the long term. Strategies that optimise herbicide performance and minimise return of weed seed to the soil are needed. Data from the surveys provide direction for research to improve weed management in this cropping system. The economic framework provides a valuable measure of evaluating likely future returns from technologies or weed management improvements.

Optical trapping of three-dimensional structures using dynamic holograms

We demonstrate the use of a spatial light modulator (SLM) to facilitate the trapping of particles in three-dimensional structures through time-sharing. This method allows particles to be held in complex, three-dimensional configurations using cycling of simple holograms. Importantly, we discuss limiting factors inherent in current phase only SLM design for applications in both optical tweezing and atom trapping.

Endoscopic surveillance practice for Barrett' s oesophagus in Scotland and early experience in implementing local guidelines

Management of columnar lined oesophagus (CLO; Barrett s oesophagus) is controversial. We prospectively audited surveillance practices in Scotland and prospectively assessed the impact of introducing local guidelines for Barrett s surveillance in Edinburgh. Most respondents were gastroenterologists. The majority take random, not four quadrant, biopsies from the CLO. In Edinburgh during 2000, 80 patients underwent surveillance. The guideline protocol was not followed in 30 (37.5%) patients. Follow up of patients without dysplasia generally conformed to the guidelines. Follow up of patients with low grade dysplasia was highly variable while management of those with high grade dysplasia followed the guidelines. Overall we found a wide variability in the management and surveillance of CLO. Early experience suggests that implementation of guidelines is helpful but there is still variation in practice.

Inflammatory-type responses after exposure to ionizing radiation in vivo: a mechanism for radiation-induced bystander effects?

Haemopoietic tissues exposed to ionizing radiation are shown to exhibit increased macrophage activation, defined by ultrastructural characteristics and increased lysosomal and nitric oxide synthase enzyme activities. Macrophage activation post-irradiation was also associated with enhanced respiratory burst activities and an unexpected neutrophil infiltration. Examination of p53-null mice demonstrated that macrophage activation and neutrophil infiltration were not direct effects of irradiation, but were a consequence of the recognition and clearance of radiation-induced apoptotic cells. Increased phagocytic cell activity was maintained after apoptotic bodies had been removed. These findings demonstrate that, contrary to expectation, recognition and clearance of apoptotic cells after exposure to radiation produces both a persistent macrophage activation and an inflammatory-type response. We also demonstrate a complexity of macrophage activation following radiation that is genotype dependent, indicating that the in vivo macrophage responses to radiation damage are genetically modified processes. These short-term responses of macrophages to radiation-induced apoptosis and their genetic modification are likely to be important determinants of the longer-term consequences of radiation exposure. Furthermore, in addition to any effects attributable to immediate radiation-induced damage, our findings provide a mechanism for the production of damage via a 'bystander' effect which may contribute to radiation-induced genomic instability and leukaemogenesis.

Cost-effectiveness of childhood immunization reminder/recall systems in urban private practices

OBJECTIVE

To assess cost and cost-effectiveness of immunization reminder/recall systems in the private sector.

METHODS

A manual postcard system (mail) was compared with a computer-based telephone system (autodialer) and control. Costs included time costs and the cost of equipment and supplies. The cost per child and the incremental cost of the intervention relative to control were computed. Cost-effectiveness ratios were computed for return visits and for immunizations delivered.

RESULTS

The average cost per child was $2.28 for the mail group and $1.47 for the autodialer group. The incremental visit cost relative to the control was higher for the mail group ($9.52) than for the autodialer group ($3.48). The autodialer was more cost-effective in delivering immunizations: $4. 06 per extra immunization (autodialer) versus $12.82 (mail).

CONCLUSIONS

Excluding start-up costs, the autodialer system was most cost-effective. Including autodialer equipment costs, the autodialer system is more cost-effective only for larger practices.

Deer antler does not represent a typical endochondral growth system: immunoidentification of collagen type X but little collagen type II in growing antler tissue

The collagen isotypes present at early (6 week) and late (5 month) stages of growing deer antler were isolated and identified. Pepsin-digested collagens were separated by differential salt fractionation, SDS-PAGE and Western blotting and subsequently identified by immunostaining. Cyanogen bromide digestion of antler tissue was used to establish a collagen type-specific pattern of peptides, and these were also identified by immunoblotting. Collagen type I was found to be the major collagen in both early- and late-stage antler. Collagen type II was present in the young antler in small amounts but was not confined to the soft "cartilaginous" tip of the antler. Collagen type XI was found in the pepsin digest of the young antler, but collagen type IX was not present at either stage of antler growth. Collagen type X was found in the young antler in all fractions studied. Microscopic study showed that the deer antler did not possess a discrete growth plate as found in endochondral bone growth. Unequivocal immunolocalization of the different collagen types in the antler were unsuccessful. These results show that, despite the presence in the antler of many cartilage collagens, growth does not occur through a simple endochondral process.

Preparation of biotinylated, affinity-purified antibodies for enzyme-linked immunoassays using blotting membrane as an antigen support

A method combining the affinity purification and biotinylation of antibodies has been developed utilizing the high-capacity binding of blotting membranes and glutaraldehyde treatment to immobilize antigen. Following reaction of the antisera with the membrane-bound antigen, the biotinylation of the antibodies is performed in situ, before release of the IgG-biotin complex with low pH buffer. The antibody is able to recognize antigen in subsequent reactions in enzyme-linked immunosorbent assays, and preliminary results have shown that the antibody can also be used in immunocytochemical localization of antigen in frozen sections. Biotinylation in situ may protect the variable region of the IgG compared to antibodies biotinylated in solution, thus increasing their antigen recognition. The method has the advantage of being suitable for multiple use of the antigen-coated membrane, making it particularly attractive where only small amounts of antigen may be available.

Collagen type X: a component of the surface of normal human, pig, and rat articular cartilage

Collagen type X, a protein generally associated with hypertrophic chondrocytes of avian and mammalian growth plate during endochondral growth of long bones, has been previously shown to be present during disruption of normal metabolic status of articular cartilage during osteoarthritis. We have demonstrated that collagen type X is present as a component of normal articular cartilage in adult human, growing pig and new-born rat. The protein was immunolocalized in these tissues at the surface of the articular cartilage and for human tissue there was some staining of chondrocytes adjacent to the "tidemark' zone. The presence of collagen type X was confirmed by isolating the protein from these tissues and its identification by SDS-PAGE and immunodetection with antibodies specific for collagen type X.

Identification of lysine-derived crosslinks in porcine collagen type X from growth plate and newly mineralized bone

Intact collagen type X cannot readily be extracted from the growth plate. Both the use of pepsin to release this molecule from tissue and the relative solubility of collagen type X following treatment of chick embryos with beta-aminopropionitrile (Chen et al., 1992) suggest that the insolubility may by brought about by the formation of lysine-derived crosslinks. By immunocytochemical labelling using antibodies specific for collagen type X, we have shown that this collagen type persists in the cartilaginous spicules present in metaphyseal bone and appears to be colocalized with collagen type II. The combined concentration of the reducible bifunctional crosslinks, dihydroxylysinonorleucine and monohydroxylysinonorleucine, in collagen type X isolated from the premineralized and newly mineralized growth plate was about 0.6 residues/ molecule, a level which might explain the relative intractability of collagen type X. Pyridinoline and deoxypyridinoline were present in very small amounts in collagen type X; this suggests that, unlike the situation in other types of collagen, few of the bifunctional crosslinks undergo maturation to pyridinium compounds. Although it is clear that collagen type X contains lysinederived crosslinks, work is in progress to establish which molecule also participates in the formation of these crosslinks.

Secretory and absorptive activity of oesophageal epithelium: evidence of circulating mucosubstances

The space between the oesophageal basal and prickle epithelial cells appears empty by standard ultrastructural preparative techniques. Fixation of human oesophageal biopsies with a variety of agents, including tannic acid, glutaraldehyde-lysine, cetylpyridinium chloride and Ruthenium Red shows that this space is filled with mucosubstances, some free, some attached to the cells as a glycocalyx. There is evidence that this material is secreted constitutively by the basal and prickle cells. This secretion may be changed or blocked by incubating oesophageal biopsies in the presence of colchicine or dinitrophenol. Incubation at 16 degrees C has the same effect. Absorption from the intercellular space may be followed using the fluid phase marker, horseradish peroxidase. Early endosomes may also be shown by their acid phosphatase activity. Incubation of biopsies at 20-22 degrees C allows early endosomes to accumulate material, but not pass it on the late endosomes.

Turnover rates of different collagen types measured by isotope ratio mass spectrometry

The rates of collagen turnover in different tissues have been estimated in growing rats previously exposed to gaseous 18O2. The abundance of the stable isotope was measured using isotope ratio mass spectrometry following combustion of isolated collagen-derived hydroxyproline. Using this method, problems of label reutilization associated with radiolabelling methods are avoided. In general the results confirm the slow turnover rates with half-lives of total collagen in skin, muscle and gut of 74, 45 and 244 d, respectively. The use of cyanogen bromide digests of whole tissues followed by isolation of collagen type-specific peptides has allowed the comparison of turnover rates of collagen types I and III, indicating that collagen type III is turned over more rapidly than type I.

Transitional cell carcinoma of the renal pelvis metastatic to the metacarpal. A case report correlating cytologic and histologic findings

This report describes the cytologic, radiologic and histologic findings in a 76-year-old male who presented with a pathologic fracture of the first metacarpal bone as the result of metastatic transitional cell carcinoma. The primary neoplasm was sited in the right renal pelvis. Metastases were also detected in the liver and confirmed cytologically. Problems encountered with the cytologic diagnosis are explained by correlation with the histologic findings. The case also illustrates the importance of clinicopathologic correlation when interpreting fine needle aspiration biopsies.

Flow cytometry of oesophageal mucosal biopsies; epidermal growth factor receptor, and CD15

Flow cytometry may be used to examine the properties of single or isolated cells. We have shown that it is possible to disaggregate and label oesophageal epithelial cells for two surface markers, CD15 and epidermal growth factor receptor. We have previously demonstrated these markers in oesophageal squamous cells using immunoperoxidase techniques. These labelled disaggregated cells could then be measured by flow cytometry.

Leakiness of gastric superficial and foveolar cells. A quantitative electron microscopic study using tannic acid

Two adjacent antral biopsies were taken endoscopically from 41 patients attending a clinic for the investigation of upper gastrointestinal tract symptoms. One was processed for histopathological grading and assessment of the Helicobacter pylori by light microscopy. The other was fixed in tannic acid, which demonstrates cell leakiness, and processed for electron microscopy. On each grid, the light (electron lucent) and dark (electron dense-leaky) gastric superficial and foveolar cells away from mechanical trauma of biopsy were counted, along with the number of H. pylori which were in contact with the epithelial cells. There was a significant relationship between histological grade of gastritis and the extent of electron microscopic damage, i.e., the degradation of normal to leaky cells and the number of H. pylori per leaky cell. If the patients were divided into two groups with minimal and maximal gastritis and compared against each other, then there was a significant difference between the two groups with respect to surface cell damage, polymorphs per unit area, the number of glands invaded by polymorphs, light/dark cells, Helicobacter grades assessed light microscopically or totals counted in contact with epithelial cells by electron microscopy, the number of Helicobacter per cell, and the age of the patients. There was no difference between the two groups on their endoscopic appearances or treatment with H2 blockers or NSAIDS.

Uptake of horseradish peroxidase by human oesophageal explants over 24 h

Human oesophageal biopsies, endoscopically and histologically normal, were incubated in Ham's F10 for periods up to 24 hours in the presence of horseradish peroxidase. The fluid phase marker was taken up most avidly by the prickle cells but to a lesser extent in the functional layers and by basal cells. Endocytosed markers proceeded to multivesicular bodies (segrosomes). Horseradish peroxidase was later deposited in lysosome-like structures and also in the Golgi apparatus. The lesser uptake by the functional cells may represent reduced access of the marker to the cells due to the intercellular barrier.

A metalloproteinase, capable of destroying cultured brain tissue isolated from rat glioma cells

A continuous rat glioma cell line, BT5C, which causes severe invasion and tissue destruction when cocultured with fetal rat brain aggregates, secreted into the culture medium a metalloproteinase in a hMr latent (86000) and an lMr active (76000) isoform. Purified preparations of the enzyme were added to cultures of fetal rat brain aggregates, which were then examined by light and by scanning electron microscopy. After 48h of enzyme exposure, destruction of the neural tissue was observed. This was morphologically similar to the tissue destruction seen when BT5C spheroids were cocultured with brain aggregates. The protease had no effect on the morphology of BT 5C tumour spheroids. The report suggests a possible role of metalloproteinases in tissue degradation during brain tumour invasion.

Isolation and characterization of a metalloproteinase secreted by rat glioma cells in serum-free culture

The isolation of a metalloproteinase secreted by a rat glioma cell line (BT5C) in serum-free media is described. After affinity purification, the activity was present as a double band with Mr 86000 and 76000 both of which required CaCl2 for activity. The enzyme was able to degrade gelatin but not casein. It was unable to degrade native types I, III, IV and V collagens but their denatured counterparts were degraded. Using a radiolabel release assay the enzyme was inhibited by EDTA, 1:10 phenanthroline and TIMP confirming that it belongs to the family of metalloproteinases. Its activity was not affected by either serine or cysteine protease inhibitors. The proteinase was activated by APMA but was unaffected by trypsin treatment.

A comparison of microwaves and heat alone in the preparation of tissue for electron microscopy

Microwaves have been used to stabilize tissues from the gastrointestinal tract for scanning electron microscopy. The temperature reached is important. Above 55-60 degrees C, epithelial cell sheets begin to lift revealing the underlying basement membrane. These cells may be recovered from the supernatant by micropore filtration or the celloidin sock technique. At higher temperatures, produced either by microwave irradiation or in a water bath, more enterocytes are released. The epithelial cells are larger with increasing temperatures, less with microwaves than with heat alone or in the presence of formaldehyde. At 70 degrees C and above, some proteins are lost and there is false localization of RNA. Some immunoperoxidase reactions are still positive after exposure of the tissue to 60 degrees C. Tissues fixed in boiling formaldehyde retain a surprisingly good morphology.

A radiolabel-release microwell assay for proteolytic enzymes present in cell culture media

A modified method for the measurement of proteolytic enzyme activity in cell culture-conditioned media has been developed. Using the release of 3H-labeled peptides from 3H-labeled gelatin the method is performed in microwell plates. The substrate is insolubilized and attached to the wells by glutaraldehyde treatment, thus eliminating the need for a precipitation step at the end of the assay. The assay is sensitive, reproducible, and convenient for small sample volumes. The effect of different protease inhibitors on activity can be assessed rapidly allowing an early characterization of the enzyme. It can also be adapted to microplate spectrophotometric analysis by staining residual substrate with Coomassie blue.

Endocytotic pathways across the human gall-bladder mucosa: permeability studies using horseradish peroxidase

Human gall-bladder epithelium obtained straight from the operating theatre was incubated in an Ussing chamber with the fluid phase marker, horseradish peroxidase (HRP), for up to 60 min. When the marker was presented on the apical surface, within 30 min it had moved readily across the apical cytoplasm in transport vesicles to receptosomes and into the lateral intercellular space, extending across the basement membrane into the lamina propria. When HRP was presented at the basal aspect, within 30 min it had moved through the lamina propria, across the basement membrane and into the lateral intercellular space. By 60 min, only small amounts had been taken up by the epithelial cells and transported to receptosomes. These data indicate a rapid transmucosal endocytotic pathway for blood- or bile-borne macromolecules.

Glycosaminoglycans in human gallbladder basement membrane: nature and quantitative changes in chronic cholecystitis

Using cuprolinic blue as a stain along with enzymic digestion, heparan sulphate has been identified as the main glycosaminoglycan in the basement membrane of human gallbladder epithelium. The amount of glycosaminoglycans was quantified by counting the number of molecular profiles cm-2 in electron micrographs of mildly, moderately and severely inflamed gallbladders. There is a significant increase (P = 0.009) in the amount of glycosaminoglycans in the basement membranes of severely inflamed gallbladders compared with cases of mild chronic cholecystitis. Differences, although present, are less significant when mild and moderate or moderate and severe cholecystitis are compared. The findings suggest that there is a continuous accumulation of heparan sulphate in the basement membrane in chronic cholecystitis which increases in amount with the severity of inflammation.

Differentiating the effects of microwave and heat on tissue proteins and their crosslinking by formaldehyde

Alkaline phosphatase activity in mouse liver blocks, cooled by an ice-bath, decreased by 50% in 5 min of microwave irradiation (280 W). This loss of protein tertiary structure has been mirrored by ultrastructural changes in the same tissue. Microwave irradiation did not produce cleavage or polymerization of lysozyme or haemoglobin. Protein formaldehyde reaction mixtures produced protein polymers between 0 degree and 40 degrees C which could be separated by SDS-polyacrylamide gel electrophoresis. Microwave irradiation of lysozyme or haemoglobin plus formaldehyde on ice-bath up to 30 min produced a similar electrophoretic pattern. When lysozyme or haemoglobin plus formaldehyde was heated to 60 degrees C for 30 min, the protein polymers migrated faster on electrophoresis, suggesting a smaller hydrodynamic volume than expected due to intramolecular crosslink formation, not opened up under the conditions of electrophoresis.

The fine structure and histochemistry of human bile duct in obstruction and choledocholithiasis

Biopsies from the common bile ducts from seven patients undergoing surgery for biliary obstruction due to stones or malignancy were studied histochemically and electron microscopically. The surface of the bile duct is lined by a tall epithelium which extends into diverticula. Apically, they contain some neutral and sialated mucosubstances. Fucosyl residues were found in the Golgi apparatus and along the apical cell membrane. The latter is lined by microvilli. There was a well-developed rough endoplasmic reticulum and Golgi apparatus and a small number of apical secretory droplets. Large numbers of lipid droplets were present basally in some cells. Lipid-containing macrophages were also seen intra-epithelially and in the lamina propria. This suggests a possible pathway for lipid transport. The glands were lined by cuboidal cells, some containing much mucus--sulphated, sialated, and neutral with a basal nucleus. A well-developed endoplasmic reticulum and Golgi apparatus were found with abundant secretory droplets. The glandular epithelium contained lysozyme, alpha-1-antitrypsin, and alpha-1-antichymotrypsin. These may play a protective role. The lamina propria contained scattered smooth muscle cells amongst the fibroblasts and inflammatory cells.

Cell death in granulomata: the role of apoptosis

Unequivocal apoptosis were seen by light microscopy in examples of leprosy, sarcoidosis, tuberculosis, Crohn's disease and foreign body granulomata. A limited electron microscopic investigation showed typical apoptotic bodies in both sarcoid and leprosy granulomata. The number of apoptosis and mitoses in granulomata were counted and their densities calculated. The wide variation in the results between individual lesions may reflect differences in disease activity.

The retention and metabolism of N tau-methylhistidine by cockerels: implications for the measurement of muscle protein breakdown determined from the excretion of N tau-methylhistidine in excreta

Excreta were collected for four consecutive days from 4- to 18-week-old cockerels following subcutaneous injection of N tau-[14CH3]methylhistidine. The recoveries of radioactivity in excreta were incomplete and progressively decreased with increasing age. Most of the radioactivity not recovered in excreta after 4 d was found in skeletal muscle where greater than 55% of the radioactivity present was in the N tau-methylhistidine-containing dipeptide, balenine. This peptide appeared to be relatively stable so that most of the labelled N tau-methylhistidine incorporated was not released during the period of the recovery measurements. The total pool of non-protein bound N tau-methylhistidine (free (free N tau-methylhistidine + balenine) in pectoral and mixed thigh muscles increased with age and relative to the daily excretion of N tau-methylhistidine. At 18 weeks the pool was 3.3 times the daily excretion of N tau-methylhistidine. These observations account for the decreasing recoveries of radioactivity in excreta described previously, due to progressive dilution of labelled N tau-methylhistidine in an expanding pool of non-protein-bound N tau-methylhistidine, part of which was relatively stable. It is concluded that excretion of N tau-methylhistidine by 4- to 18-week-old cockerels cannot be used as a reliable index of muscle protein breakdown in vivo.

Permeability of the mouse gallbladder to blood-borne horseradish peroxidase

Horseradish peroxidase (HRP) was administered intravenously to mice by bolus injection. The subsequent uptake and fate of the HRP by the lateral and basal cell surfaces of resting and stimulated gallbladder epithelial cells was followed by light and electron microscopy. At 10 min after injection, HRP was visible in the lamina propria of the gallbladder and within 20 min of injection, HRP had permeated the basement membrane and had entered the lateral intercellular space, extending as far as the apical tight junction. Over the following 30 min, there was evidence of vesicular epithelial HRP uptake and 1 h after injection, HRP was visible in epithelial secretory granules within the lumen of the gallbladder and apical transport vesicles. These data provide evidence of a blood-to-bile transport pathway which could represent an important route of entry to bile by various blood-borne macromolecules.

The identification of the N tau-methyl histidine-containing dipeptide, balenine, in muscle extracts from various mammals and the chicken

The occurrence of the dipeptide, balenine (beta-alanyl-N tau-methyl histidine), has been identified by comparative chromatography in extracts of muscles from 9 species of mammal, including man, and the chicken. The identity of the dipeptide from 6 mammalian species and chicken was confirmed by preparative isolation prior to determination of the amino acid composition and N-terminal residue. In all cases, the dipeptide contained equimolar amounts of beta-alanine and N tau-methyl histidine with beta-alanine as the N-terminus. The concentration of the dipeptide varied dramatically between species, being just detectable in the muscle of man and rat while present at concentrations of up to 14 mumol/g wet muscle in adult pigs. It is proposed that balenine, like carnosine and anserine, should be regarded as a normal constituent of muscle.