Molecular changes in the expression of human colonic nutrient transporters during the transition from normality to malignancy

Healthy colonocytes derive 60-70% of their energy supply from short-chain fatty acids, particularly butyrate. Butyrate has profound effects on differentiation, proliferation and apoptosis of colonic epithelial cells by regulating expression of various genes associated with these processes. We have previously shown that butyrate is transported across the luminal membrane of the colonic epithelium via a monocarboxylate transporter, MCT1. In this paper, using immunohistochemistry and in situ hybridisation histochemistry, we have determined the profile of MCT1 protein and mRNA expression along the crypt to surface axis of healthy human colonic tissue. There is a gradient of MCT1 protein expression in the apical membrane of the cells along the crypt-surface axis rising to a peak in the surface epithelial cells. MCT1 mRNA is expressed along the crypt-surface axis and is most abundant in cells lining the crypt. Analysis of healthy colonic tissues and carcinomas using immunohistochemistry and Western blotting revealed a significant decline in the expression of MCT1 protein during transition from normality to malignancy. This was reflected in a corresponding reduction in MCT1 mRNA expression, as measured by Northern analysis. Carcinoma samples displaying reduced levels of MCT1 were found to express the high affinity glucose transporter, GLUT1, suggesting that there is a switch from butyrate to glucose as an energy source in colonic epithelia during transition to malignancy. The expression levels of MCT1 in association with GLUT1 could potentially be used as determinants of the malignant state of colonic tissue.

Expression of monosaccharide transporters in intestine of diabetic humans

Noninsulin-dependent diabetes mellitus (NIDDM) is an increasingly common disease, which brings a number of life-threatening complications. In rats with experimentally induced diabetes, there is an increase in the capacity of the intestine to absorb monosaccharides. We have examined the activity and the expression of monosaccharide transporters in the intestine of patients suffering from NIDDM. Na(+)-dependent D-glucose transport was 3.3-fold higher in brush-border membrane (BBM) vesicles isolated from duodenal biopsies of NIDDM patients compared with healthy controls. Western analysis indicated that SGLT1 and GLUT5 protein levels were also 4.3- and 4.1-fold higher in diabetic patients. This was associated with threefold increases in SGLT1 and GLUT5 mRNA measured by Northern blotting. GLUT2 mRNA levels were also increased threefold in the intestine of diabetic patients. Analysis of other BBM proteins indicated that the activity and abundance of sucrase and lactase were increased by 1.5- to 2-fold and the level of the structural proteins villin and beta-actin was enhanced 2-fold in diabetic patients compared with controls. The increase in the capacity of the intestine to absorb monosaccharides in human NIDDM is due to a combination of intestinal structural change with a specific increase in the expression of the monosaccharide transporters SGLT1, GLUT5, and GLUT2.

Descriptive information about Down syndrome: a content analysis of serum screening leaflets

It is recommended practice that prior to prenatal screening, women receive information about the condition(s) being tested for. The present study critically evaluated information about Down syndrome as contained in 80 leaflets provided to pregnant women in the UK prior to serum screening. First, a content analysis by information type was conducted to give an overall picture of the material provided. Second, the image of the condition as conveyed by the content was analysed and compared with a similar study of cystic fibrosis (CF) screening leaflets. The majority of information (89%) was of a medico-clinical nature, with 11% addressing other issues associated with Down syndrome. The median number of sentences describing the condition was one, with 33% of the leaflets containing no descriptive information. Overall, a negative image of Down syndrome was conveyed by the leaflets, which contrasted with a more neutral image of CF in the comparison study. In order to facilitate informed choices, more attention should be paid to providing women with information about Down syndrome prior to serum screening. Such information needs to be more balanced in its construction, with thought given to the needs of the reader, and to the tone and the content of the message conveyed.

Characterization of Salmonella associated with pig ear dog treats in Canada

In the summer of 1999, the incidence of Salmonella enterica serotype Infantis infections in Alberta rose dramatically. Subsequent laboratory and epidemiological investigations established that an outbreak of human disease caused by this organism was occurring across Canada and was associated with pet treats for dogs produced from processed pig ears. Laboratory investigations using phage typing and pulsed-field gel electrophoresis (PFGE) established that isolates of Salmonella serotype Infantis from pig ear pet treats and humans exposed to pig ear pet treats comprised a well-defined subset of all isolates analyzed. Of the 53 subtypes of Salmonella serotype Infantis obtained around the time of the outbreak as defined by PFGE and phage typing, only 6 subtypes were associated with both human infection and isolation from pig ears. Together with information from epidemiological studies, these investigations established pig ear pet treats as the cause of the Salmonella serotype Infantis outbreak. The results are consistent with a model in which contaminated pig ear pet treats constitute a long-term, continuing vehicle for infection of the human population rather than causing temporally delimited point-source outbreaks. During the course of this outbreak, several other Salmonella serotypes were also isolated from pet treats, suggesting these products may be an important source of enteric infection in both humans and dogs. Though isolates of Salmonella serotypes other than Salmonella serotype Infantis from pet treats were also subjected to PFGE and phage typing, no link with human disease could be definitively established, and the contribution of pig ear pet treats to human disease remains unclear. Elimination of bacterial contamination from pet treats is required to reduce the risk of infection from these products.

[Retinal hazard from blue light emitting diode]

PURPOSE

To compare the effect of exposure time from a blue(460 nm) light emitting diode(LED) on the morphology of the outer retina and determine conditions where damage occurs.

MATERIALS AND METHODS

Young adult rhesus monkeys were anesthetized, and received blue LED exposure from a modified slit-lamp. A 3 mm beam of 0.85 mW was imaged onto the retina through a lens positioned before the cornea and exposure damage was determined at time intervals for 12 to 90 min. Fundus photography, fluorescein angiography(FAG), retinal tomography(HRT), and s-cone electororetinogram(S-ERG) were recorded at baseline, 2, and 30 days.

RESULTS

Two days after 40 min exposure, there was a grey, discolored region, which was over-fluorescent in FAG, and an incresse in HRT and S-ERG corresponding to the site which was exposed to LED light. In histological examination at 30 days, the LED had caused produced a marked disruption of the disks of photoreceptor cells, damaged retinal pigment epithelium(RPE) apical villi, and a loss of RPE melanin after 90 min exposure.

CONCLUSION

A threshold level was found around 40 min. This morphological damage may impair function and continuous exposure to blue light is potentially dangerous to vision.

A phase I study of paclitaxel and altretamine as second-line therapy to cisplatin regimens for ovarian cancer

PURPOSE

The efficacy and pharmacokinetics of paclitaxel when combined with altretamine for ovarian cancer were studied.

METHODS

A group of 30 patients, whose only chemotherapy was one or more cisplatin-based non-paclitaxel-containing regimens and whose ovarian cancer failed to respond or had relapsed within 6 months of their last platinum regimen, received paclitaxel as a 3-h intravenous infusion and altretamine given orally in four divided doses daily for 14 days repeated every 28 days. Doses were escalated from paclitaxel/altretamine 135/150 mg/m2 to 250/300 mg/m2 in cohorts of three patients.

RESULTS

The dose-limiting toxicities at 250/300 mg/m2 were WHO grade 3 myalgias and arthralgias in two patients and grade 3 lethargy, stomach cramps, peripheral neuropathy and vomiting in single patients. Considering all dose levels in cycle 1, 16 patients had grade 3 or 4 neutropenia but there was only one episode of febrile neutropenia. Other grade 3 toxicities were vomiting in four patients, myalgias in three, peripheral neuropathy in two and lethargy in two. Grade 3 alopecia occurred in 23 patients. Three patients achieved a complete response and 12 achieved a partial response for an overall objective response rate of 50%. Responses occurred at all dose levels of 175/150 mg/m2 and higher. The median freedom from progression was 35 weeks, with a median survival of 55 weeks. Altretamine did not alter the pharmacokinetics of paclitaxel and there were no consistent differences in paclitaxel pharmacokinetic parameters or toxicities between course 1 and 2. No dose-response relationships were evident above paclitaxel/altretamine 175/150 mg/m2.

CONCLUSION

Paclitaxel and altretamine can be safely combined and with a high response rate in relapsed ovarian cancer, justifying further studies with this combination.

Rational and irrational aspects of countertransference

Countertransference in therapy stems from biological tendencies and social learning influences that involve mild or heavy prejudiced thinking, feeling, and behaving. Several reasons are given why it is almost inevitable and has both beneficial and destructive aspects-not either/or but both/and. It is hypothesized that therapists can well make good use of countertransference if they strive to employ it in a preferential, experimental rather than an absolutist musturbating manner.

Quality of written information used in Down syndrome screening

A qualitative assessment was performed on 81 leaflets used in maternal serum Down syndrome screening from National Health Service (NHS) obstetric units and private screening services. Quality was assessed by factual content, presentation and reading ease and this was amalgamated into a single overall score expressed as a percentage of the maximum possible score. Eleven (14%) leaflets included all eight factual items recommended by the Royal College of Obstetricians and Gynaecologists (RCOG); only one included these and a further nine items recognised as important to the consumer. Three (4%) leaflets contained information that was incorrect and 17 (21%) that was misleading or inconsistent. Using published criteria six (7%) leaflets were well presented and ten (12%) were fairly easy to read. The average reading age was 13-14 years. The overall quality score showed that five leaflets had 80% or more of the total possible score. However a substantial number, 15 (19%), were totally unacceptable having scores of 40% or less. In general the quality of leaflets used in the UK is considered poor. A national peer-reviewed leaflet should be prepared which can be modified to suit local policy.

Illness outbreak associated with Escherichia coli O157:H7 in Genoa salami. E. coli O157:H7 Working Group

BACKGROUND

An outbreak of Escherichia coli O157:H7 infection was identified in the spring of 1998, with a 7-fold increase in the number of laboratory-confirmed E. coli O157:H7 cases in southern Ontario. This prompted an intensive investigation by local, provincial and federal public health officials.

METHODS

Case interviews of 25 people from southern Ontario were conducted using a broad food history and environmental exposure survey. Laboratory investigations involved both case and food sampling. Specimens of foods sold locally and reportedly consumed by those affected were tested. Common suppliers of suspected foods were identified by cross-referencing suppliers' lists with stores frequented by those who fell ill. A case-control study involving 25 cases and 49 age-matched controls was conducted. This was followed by a comprehensive environmental investigation of the meat processing plant identified as the source of the E. coli.

RESULTS

Thirty-nine outbreak-related cases occurred between April 3 and June 2, 1998. Of the 36 case specimens tested all were positive for E. coli O157:H7. The case-control study identified Genoa salami as the most probable (odds ratio 8 [confidence interval 2-35]) source of the outbreak. Samples of Genoa salami produced by the most commonly identified supplier later tested positive for E. coli O157:H7, and the pathogen matched the same pulsed-field gel electrophoresis pattern and phage type of the case specimens.

INTERPRETATION

Our investigation, which led to a national recall of the brand of dry fermented Genoa salami identified as the source of the outbreak, supports an adherence to stringent manufacturing requirements for fermented meat products. A review of the Canadian standards for fermented meat processing and the effectiveness of their implementation is warranted.

Sustained cognitive improvement following treatment of Alzheimer's disease with donepezil

OBJECTIVES

To audit response to the anticholinesterase inhibitor donepezil in patients referred to a specialist memory clinic, to identify possible means of targeting the drug more accurately.

DESIGN

All referrals to the clinic who were assessed and treated against a protocol, with structured follow-up.

SUBJECTS

All referrals of any age with the diagnosis of probable Alzheimer's disease, mild to moderately severe. Main outcome measures Cognitive improvement as measured by serial ADAS-cog and MMSE examinations.

RESULTS

Two hundred and eight-two patients commenced on treatment, improved cognitive functioning in over 65% of patients reaching 3 months (N=184), 51% on intention to treat analysis (N=231), with significantly greater improvement (p=0.03) in those aged 65 and under. Carer reports of behavioural improvement not always linked to cognitive improvement. Trend to increased response in those on concomitant antidepressants.

CONCLUSION

Three-month assessment for response prior to agreeing continuation of treatment selects a group who maintain their response. Younger patients should be targeted for early assessment and treatment.

Envoplakin, a possible candidate gene for focal NEPPK/esophageal cancer (TOC): the integration of genetic and physical maps of the TOC region on 17q25

Focal nonepidermolytic palmoplantar keratoderma (NEPPK), or tylosis, is an autosomal, dominantly inherited disorder of the skin that manifests as focal thickening of the palmar and plantar surfaces. In three families studied, the skin disorder cosegregates with esophageal cancer and oral lesions. New haplotype analysis, presented here, places the tylosis esophageal cancer (TOC) locus between D17S1839 and D17S785. Envoplakin (EVPL) is a protein component of desmosomes and the cornified envelope that is expressed in epidermal and esophageal keratinocytes and has been localized to the TOC region. Mutation analysis of EVPL in the three affected families failed to show tylosis-specific mutations, and haplotype analysis of three intragenic sequence polymorphisms of the EVPL gene placed it proximal to D17S1839. Confirmation of the exclusion of EVPL as the TOC gene by location was obtained by integration of the genetic and physical mapping data using radiation hybrid, YAC, BAC, and PAC clones. This new physical map will allow further identification of candidate genes underlying NEPPK associated with esophageal cancer, which may also be implicated in the development of sporadic squamous cell esophageal carcinoma and Barrett's adenocarcinoma.

Serum growth hormone measurements in clinical practice: An audit of performance from the UK National External Quality Assessment scheme

The replacement of growth hormone (GH) radioimmunoassays with a variety of more specific immunometric methods in diagnostic service laboratories has led to a worsening of between-laboratory agreement, reflecting differences in method bias. Incorrect calibration and differences in specificity are important causes of method bias, but the impact of this on interpretation is not clear. In order to maximize the diagnostic reliability of GH testing for small stature, manufacturers should carefully calibrate their methods against the appropriate GH International Standard, and should use antibodies of broadly agreed specificity. Laboratories performing GH tests should participate in a reliable External Quality Assessment (EQA) scheme and guidelines for investigation that incorporate normal GH responses should be agreed.

Spuriously elevated plasma calcitonin in a patient with a thyroid nodule not associated with medullary thyroid carcinoma

An increase in plasma calcitonin concentration is widely regarded as a specific and sensitive indication of underlying medullary thyroid carcinoma (MTC). We present a case in which the association of increased plasma calcitonin concentration and a thyroid nodule was not due to MTC. Subsequent measurement of plasma calcitonin by a variety of methods highlighted the variability that exists in calcitonin measurement and the potential for clinically misleading results. The rationale for investigation and treatment of MTC, including a recommendation to screen all patients with thyroid nodules using plasma calcitonin measurement, is based on the use of specific two-site calcitonin assays which are not universally used in the UK or USA.

Identification and characterization of a monocarboxylate transporter (MCT1) in pig and human colon: its potential to transport L-lactate as well as butyrate

1. Oligonucleotide primers based on the human heart monocarboxylate transporter (MCT1) cDNA sequence were used to isolate a 544 bp cDNA product from human colonic RNA by reverse transcription-polymerase chain reaction (RT-PCR). The sequence of the RT-PCR product was identical to that of human heart MCT1. Northern blot analysis using the RT-PCR product indicated the presence of a single transcript of 3.3 kb in mRNA isolated from both human and pig colonic tissues. Western blot analysis using an antibody to human MCT1 identified a specific protein with an apparent molecular mass of 40 kDa in purified and well-characterized human and pig colonic lumenal membrane vesicles (LMV). 2. Properties of the colonic lumenal membrane L-lactate transporter were studied by the uptake of L-[U-14C]lactate into human and pig colonic LMV. L-Lactate uptake was stimulated in the presence of an outward-directed anion gradient at an extravesicular pH of 5.5. Transport of L-lactate into anion-loaded colonic LMV appeared to be via a proton-activated, anion exchange mechanism. 3. L-Lactate uptake was inhibited by pyruvate, butyrate, propionate and acetate, but not by Cl- and SO4(2-). The uptake of L-lactate was inhibited by phloretin, mercurials and alpha-cyano-4-hydroxycinnamic acid (4-CHC), but not by the stilbene anion exchange inhibitors, 4,4'-diisothiocyanostilbene-2, 2'-disulphonic acid (DIDS) and 4-acetamido-4'-isothiocyanostilbene-2, 2'-disulphonic acid (SITS). 4. The results indicate the presence of a MCT1 protein on the lumenal membrane of the colon that is involved in the transport of L-lactate as well as butyrate across the colonic lumenal membrane. Western blot analysis showed that the abundance of this protein decreases in lumenal membrane fractions isolated from colonic carcinomas compared with that detected in the normal healthy colonic tissue.

Population-based analysis of 10,766 hospitalizations for mandibular fractures in California, 1991 to 1993

BACKGROUND

This study describes mandibular fracture incidence, causes, and consequences in a large population.

METHODS

California hospital discharge data from 1991 to 1993 were examined to describe causes, lengths of stay, and hospital charges for patients hospitalized for mandibular fractures. Rates were calculated per 100,000 population.

RESULTS

There were 10,766 discharges with mandibular fracture as principal diagnosis or as diagnoses two through five on the discharge record (rate=11.5). Of these, 2,694 had mandibular fracture as the only diagnosis (principal diagnosis). For all 10,766 cases, assaults were responsible for more than half (54.0%) of all admissions for mandibular fracture. The highest rates were found among males (18.7), blacks (43.0), and adults aged 16 to 20 (26.5). Charges for the initial hospitalization (excluding physician's fees) for the 2,694 cases with only a diagnosis of mandibular fracture were used to estimate mean charges ($8,740). The total extrapolated 1993 inflation-adjusted hospital charges for mandibular fractures were $34 million per year. Most patients' bills were submitted to government payers, such as Medicaid.

CONCLUSION

Treatment of mandibular fractures represents a considerable cost to public-supported programs as well as to patients.

Effect of xanthine oxidase inhibition on endothelium-dependent and nitrergic relaxations

The effects of inhibition of xanthine oxidase on responses mediated by nitric oxide (NO) were examined using the selective xanthine oxidase inhibitors allopurinol and 4-amino-6-hydroxypyrazolo[3,4-d]pyrimidine (AHPP). In rat aortic rings precontracted with phenylephrine (1 microM), allopurinol (300 microM) and AHPP (100, 300 microM) significantly reduced tone, an effect not seen after inhibition of NO synthase with Nomega-nitro-L-arginine (NOLA 100 microM). Relaxations produced by acetylcholine (0.01-10 microM) were significantly enhanced by AHPP (100, 300 microM) but not by allopurinol. Nitrergic relaxations in the rat anococcygeus muscle (field stimulation 1 ms pulses; 1 Hz: 10 s) were not affected by either allopurinol or AHPP. However, relaxations produced by exogenous NO (0.25 microM) were significantly enhanced by AHPP, allopurinol (100 microM) and superoxide dismutase (100 U/ml). Xanthine (500 microM) partially, but significantly, reversed the enhancement produced by AHPP. These findings suggest that superoxide generated by xanthine oxidase modulates the activity of basal and stimulated NO derived from the rat aortic endothelium, but does not affect the activity of the nitrergic transmitter in the rat anococcygeus muscle, despite its ability to modulate responses to exogenous NO.