Characterization of the genomic structure of the human vitamin C transporter SVCT1 (SLC23A2)

Vitamin C (L-ascorbic acid), a critical cofactor for intracellular enzymatic reactions, functions as a scavenger of free oxygen radicals and is an essential micronutrient. Vitamin C is actively transported into cells by one of two closely related sodium-dependent transporters, SVCT1 or SVCT2. In this paper, we report the complete sequencing and gene structure of SLC23A2, the gene encoding SVCT1. The1797-bp cDNA sequence (open reading frame) of the SLC23A2 gene was derived from a compact genomic sequence of 7966 bp [translation initiation codon (ATG) to poly A tail], which is divided into 14 exons. Furthermore, repetitive or masked elements constituted 17.98% of the gene; there were 4 Alu sequences and 5 MIR (Mammalian Interspersed Repetitive element) sequences. A search for common variants in SLC23A2, using current bioinformatic tools and direct resequencing of control populations, failed to identify common single nucleotide polymorphisms. The start of transcription was mapped to a position -47 relative to the ATG; the immediate 5' sequence was determined and analyzed for possible consensus binding sites for known transcription factors. Our findings will serve as the foundation for investigation of the regulation and expression of the tissue-specific sodium-dependent vitamin C transporter, SLC23A2.

Effect of antioxidant supplementation on ozone-induced lung injury in human subjects

To determine whether antioxidants can influence human susceptibility to ozone (O(3))-induced changes in lung function and airway inflammation, we placed 31 healthy nonsmoking adults (18 to 35 yr old) on a diet low in ascorbate for 3 wk. At 1 wk, subjects were exposed to filtered air for 2 h while exercising (20 L/min/m(2)), and then underwent bronchoalveolar lavage (BAL) and were randomly assigned to receive either a placebo or 250 mg of vitamin C, 50 IU of alpha-tocopherol, and 12 oz of vegetable cocktail daily for 2 wk. Subjects were then exposed to 0.4 ppm O(3) for 2 h and underwent a second BAL. On the day of the O(3) exposure, supplemented subjects were found to have significantly increased levels of plasma ascorbate, tocopherols, and carotenoids as compared with those of the placebo group. Pulmonary function testing showed that O(3)-induced reductions in FEV(1) and FVC were 30% and 24% smaller, respectively, in the supplemented cohort. In contrast, the inflammatory response to O(3) inhalation, as represented by the percent neutrophils and the concentration of interleukin-6 recovered in the BAL fluid at 1 h after O(3) exposure was not different for the two groups. These data suggest that dietary antioxidants protect against O(3)-induced pulmonary function decrements in humans.

A snapshot of waiting times for cancer surgery provided by surgeons affiliated with regional cancer centres in Ontario

BACKGROUND

There is evidence that delays in treatment result in increased psychosocial morbidity for patients diagnosed with cancer. We evaluated waiting times for care among cancer patients treated by surgeons affiliated with regional cancer centres in Ontario.

METHODS

Dates for 5 key events related to the surgical management of a patient with cancer were collected by a convenience sample of surgeons who treat breast, gynecologic, colorectal, head and neck, thoracic and urologic cancers. The key events were initial referral, first surgical visit, main treatment decision, major surgery and receipt of postoperative pathology report. The surgeons were also asked to judge the appropriateness of the waiting times for the intervals studied and to identify factors associated with inappropriate delays.

RESULTS

A total of 62 surgeons affiliated with 8 regional cancer centres participated; data were collected for 1456 patients who underwent assessment and whose surgical visit occurred between Jan. 31 and May 31, 2000. The median waiting time from referral to first visit was 11.0 days, from first visit to treatment decision 0.0 days, from treatment decision to surgery 20.0 days and from surgery to receipt of the pathology report 8.0 days. The median waiting times for the 2 summary intervals (referral to surgery and referral to receipt of the pathology report) were 37.0 and 48.0 days respectively. The waiting times varied by cancer type; for example, the median time from referral to surgery varied from 29.0 days for colorectal cancers to 64.0 days for urologic cancers. The same interval varied from 19.0 to 43.0 days by treatment centre. The waiting times did not vary substantially by patient age. The surgeons judged that 344 (37.2%) of the 925 patients with dates for the referral-to-surgery interval had inappropriately long waiting times. They indicated that contributing factors to these inappropriate waits were shortage of operating room time (in 181 cases), lack of other resources such as diagnostic tests or allied health personnel (in 156) and patient preference or circumstance (in 28) (factors were not mutually exclusive).

INTERPRETATION

Many of the patients with cancer seen by surgeons affiliated with regional cancer centres in Ontario may be experiencing significant delays in the assessment and treatment of their cancer.

A new recommended dietary allowance of vitamin C for healthy young women

The recently released Recommended Dietary Allowance of vitamin C for women, 75 mg daily, was based on data for men. We now report results of a depletion-repletion study with healthy young women hospitalized for 186 +/- 28 days, using vitamin C doses of 30-2,500 mg daily. The relationship between dose and steady-state plasma concentration was sigmoidal. Only doses above 100 mg were beyond the linear portion of the curve. Plasma and circulating cells saturated at 400 mg daily, with urinary elimination of higher doses. Biomarkers of endogenous oxidant stress, plasma and urine F(2)-isoprostanes, and urine levels of a major metabolite of F(2)-isoprostanes were unchanged by vitamin C at all doses, suggesting this vitamin does not alter endogenous lipid peroxidation in healthy young women. By using Food and Nutrition Board guidelines, the data indicate that the Recommended Dietary Allowance for young women should be increased to 90 mg daily.

Enzyme therapy for lysosomal acid lipase deficiency in the mouse

Lysosomal acid lipase (LAL) is the critical enzyme for the hydrolysis of the triglycerides (TG) and cholesteryl esters (CE) delivered to lysosomes. Its deficiency produces two human phenotypes, Wolman disease (WD) and cholesteryl ester storage disease (CESD). A targeted disruption of the LAL locus produced a null (lal( -/-)) mouse model that mimics human WD/CESD. The potential for enzyme therapy was tested using mannose terminated human LAL expressed in Pichia pastoris (phLAL), purified, and administered by tail vein injections to lal( -/-) mice. Mannose receptor (MR)-dependent uptake and lysosomal targeting of phLAL were evidenced ex vivo using competitive assays with MR-positive J774E cells, a murine monocyte/macrophage line, immunofluorescence and western blots. Following (bolus) IV injection, phLAL was detected in Kupffer cells, lung macrophages and intestinal macrophages in lal( -/-) mice. Two-month-old lal( -/-) mice received phLAL (1.5 U/dose) or saline injections once every 3 days for 30 days (10 doses). The treated lal( -/-) mice showed nearly complete resolution of hepatic yellow coloration; hepatic weight decreased by approximately 36% compared to PBS-treated lal( -/-) mice. Histologic analyses of numerous tissues from phLAL-treated mice showed reductions in macrophage lipid storage. TG and cholesterol levels decreased by approximately 50% in liver, 69% in spleen and 50% in small intestine. These studies provide feasibility for LAL enzyme therapy in human WD and CESD.

Clinical practice guidelines for the care and treatment of breast cancer: 13. Sentinel lymph node biopsy

OBJECTIVE

To provide information and recommendations to women with breast cancer and their physicians regarding what is now known about sentinel lymph node (SLN) biopsy.

OPTIONS

Axillary dissection; SLN biopsy followed by backup axillary dissection; SLN biopsy.

OUTCOMES

Accurate determination of cancer stage, resulting in better-informed therapeutic decisions.

EVIDENCE

Systematic review of English-language literature published from January 1991 to December 2000 retrieved primarily from MEDLINE and CANCERLIT.

RECOMMENDATIONS

Axillary dissection is the standard of care for the surgical staging of operable breast cancer. If a patient requests or is offered SLN biopsy, the benefits and risks as well as what is and is not known about the procedure should be outlined. Patients should be informed of the number of SLN biopsies performed by the surgeon and the surgeon's success rate with the procedure, as determined by the identification of the SLN and the false-negative rate (the presence of tumour cells in the axillary nodes when the SLN biopsy result is negative). Before surgeons replace axillary dissection by SLN biopsy as the staging procedure at their institution, they should (a) familiarize themselves with the literature on the topic and the techniques needed to perform the procedure, (b) follow a defined protocol for all 3 aspects of the procedure (nuclear medicine, surgery, pathology) and (c) perform backup axillary dissection until an acceptable success rate (as determined by the identification of the SLN and the false-negative rate) is achieved. A surgeon who performs breast cancer surgery infrequently should not perform SLN biopsy. A positive SLN biopsy result or failure to identify an SLN should prompt full axillary dissection. SLN biopsy is contraindicated in women who have clinically palpable nodes, locally advanced breast cancer, multifocal tumours, previous breast surgery or previous irradiation of the breast. Staining of tissue sections with hematoxylin and eosin, and not immunohistochemical analysis for cytokeratin, should determine adjuvant therapy. Participation in randomized clinical trials is encouraged. [A patient version of these guidelines appears in Appendix 1.]

VALIDATION

Internal validation within the Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer; no external validation.

The cAMP-protein kinase A signal transduction pathway modulates ethanol consumption and sedative effects of ethanol

Ethanol and other drugs of abuse modulate cAMP-PKA signaling within the mesolimbic reward pathway. To understand the role of the cAMP-PKA signal transduction in mediating the effects of ethanol, we have studied ethanol consumption and the sedative effects of ethanol in three lines of genetically modified mice. We report that mice with the targeted disruption of one Gsalpha allele as well as mice with reduced neuronal PKA activity have decreased alcohol consumption compared with their wild-type littermates. Genetic reduction of cAMP-PKA signaling also makes mice more sensitive to the sedative effects of ethanol, although plasma ethanol concentrations are unaffected. In contrast, mice with increased adenylyl cyclase activity resulting from the transgenic expression of a constitutively active form of Gsalpha in neurons within the forebrain are less sensitive to the sedative effects of ethanol. Thus, the cAMP-PKA signal transduction pathway is critical in modulating sensitivity to the sedative effects of ethanol as well as influencing alcohol consumption.

A prospective trial of inhaled nitric oxide in clinical lung transplantation

BACKGROUND

Reperfusion injury (RI) is a major cause of mortality and morbidity among lung transplant recipients. We sought to determine if prophylactic administration of inhaled nitric oxide (NO) to lung transplant recipients at reperfusion would prevent RI. We also hypothesized that if prophylactic NO proves ineffective in preventing RI then it may improve pulmonary hemodynamics and gas exchange in the subset of patients who develop RI.

METHODS

After informed consent, 28 consecutive, adult lung transplant recipients received NO at 20 ppm at reperfusion. NO was withdrawn for 15 min at 6 and 12 hr after reperfusion, and gas exchange and hemodynamics were measured.

RESULTS

Five of the 28 lung transplant recipients (18%) developed RI. Withdrawal of NO for 15 min in this subset of patients resulted in a significant rise in mean pulmonary artery pressure and a reduction in oxygenation index. All five patients with RI were kept on inhaled NO until full functional recovery of the allograft and were then weaned from mechanical ventilation. None required extracorporeal membrane oxygenation support; the early mortality in this group was 20% (1/5). The remaining 23 patients without RI had uneventful early postoperative course and were weaned from NO and mechanical ventilation within 36 hr of transplantation.

CONCLUSIONS

Prophylactic-inhaled NO does not prevent RI in human lung transplantation. However, inhaled NO, started at reperfusion, improves gas exchange and reduces pulmonary artery pressure in those patients who develop RI.

Chemoprevention of breast cancer. A joint guideline from the Canadian Task Force on Preventive Health Care and the Canadian Breast Cancer Initiative's Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer

OBJECTIVE

To assist women and their physicians in making decisions regarding the prevention of breast cancer with tamoxifen and raloxifene.

EVIDENCE

Systematic review of English-language literature published from 1966 to August 2000 retrieved from MEDLINE, HealthSTAR, Current Contents and Cochrane Library.

VALUES

The strength of evidence was evaluated using the methods of the Canadian Task Force on Preventive Health Care and the Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer.

RECOMMENDATIONS

Women at low or normal risk of breast cancer (Gail risk assessment index < 1.66% at 5 years): There is fair evidence to recommend against the use of tamoxifen to reduce the risk of breast cancer in women at low or normal risk of the disease (grade D recommendation). Women at higher risk of breast cancer (Gail index > or = 1.66% at 5 years): Evidence supports counselling women at high risk on the potential benefits and harms of breast cancer prevention with tamoxifen (grade B recommendation). The cutoff for defining high risk is arbitrary, but the National Surgical Adjuvant Breast and Bowel Project P-1 Study included women with a 5-year projected risk of at least 1.66% according to the Gail index, and the average risk of patients entered in the trial was 3.2%. Examples of high-risk clinical situations are 2 first-degree relatives with breast cancer, a history of lobular carcinoma in situ or a history of atypical hyperplasia. As the risk of breast cancer increases above 5% and the benefits outweigh the harms, a woman may choose to take tamoxifen. The duration of tamoxifen use in such situations is 5 years based on the results from trials of tamoxifen involving women with early breast cancer. If a woman raises concerns or has already been evaluated and is calculated to be at high risk, then individuals experienced and skilled in counselling may discuss the potential benefits and harms of tamoxifen use. Important additional issues: Prevention of breast cancer with raloxifene: Current evidence does not support recommending chemoprevention of breast cancer with raloxifene outside of a clinical trial setting. Screening using the Gail risk assessment index: This index was the main eligibility criterion for enrolling women in the one study that showed potential benefit from chemoprevention. However, it has not been evaluated for use as a routine screening or case-finding instrument; validation of the index is required. Overall, current evidence does not support a shift to its routine use in physicians' offices for screening or case finding. However, when a woman or her physician is concerned about the woman's increased risk of breast cancer, the index can be a useful tool in deciding whether to pursue an in-depth discussion of the potential benefits and harms of chemoprevention. Hence, the approach to identifying women at higher risk who warrant counselling and shared decision-making will vary across practices. (The risk assessment index is available online at http://bcra.nci.nih.gov/brc/). [A patient version of these guidelines appears in Appendix 2.]

VALIDATION

The authors' original text was revised by both the Canadian Task Force on Preventive Health Care and the Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer. The final document reflects a consensus of these contributors.

SPONSOR

Health Canada. COMPLETION DATE: February 2001.

Baseline staging tests in primary breast cancer: a practice guideline

BACKGROUND

Breast cancer develops in over 7000 women each year in Ontario. These patients will all undergo some staging work-up at diagnosis. The Breast Cancer Disease Site Group of the Cancer Care Ontario Practice Guidelines Initiative reviewed the evidence and indications for routine bone scanning, liver ultrasonography and chest radiography in asymptomatic women who have undergone surgery for breast cancer.

METHODS

A systematic review of the published literature was combined with a consensus interpretation of the evidence in the context of conventional practice.

RESULTS

There were 11 studies of bone scanning reported between 1972 and 1980, involving a total of 1307 women; bone scans detected skeletal metastases in 6.8% of those with stage I breast cancer, 8.8% with stage II and 24.5% with stage III. A total of 5407 women participated in 9 studies of bone scanning reported between 1985 and 1995; in these studies, bone scans detected skeletal metastases in only 0.5% of women with stage I disease, 2.4% with stage II and 8.3% with stage III. Among 1625 women in 4 studies of liver ultrasonography reported between 1988 and 1993, hepatic metastases were detected in 0% of patients with stage I disease, 0.4% with stage II and 2.0% with stage III. Among 3884 patients in 2 studies of chest radiography published in 1988 and 1991, lung metastases were detected in 0.1% of those with stage I, 0.2% with stage II and 1.7% with stage III. False-positive rates ranged from 10% to 22% for bone scanning, 33% to 66% for liver ultrasonography and 0% to 23% for chest radiography. The false-negative rate for bone scanning was about 10%.

RECOMMENDATIONS

The following recommendations apply to women with newly diagnosed breast cancer who have undergone surgical resection and who have no symptoms, physical signs or biochemical evidence of metastases. Routine bone scanning, liver ultrasonography and chest radiography are not indicated before surgery. In women with intraductal and pathological stage I tumours, routine bone scanning, liver ultrasonography and chest radiography are not indicated as part of baseline staging. In women who have pathological stage II tumours, a postoperative bone scan is recommended as part of baseline staging. Routine liver ultrasonography and chest radiography are not indicated in this group but could be considered for patients with 4 or more positive lymph nodes. In women with pathological stage III tumours, bone scanning, liver ultrasonography and chest radiography are recommended postoperatively as part of baseline staging. In women for whom treatment options are restricted to tamoxifen or hormone therapy, or for whom no further treatment is indicated because of age or other factors, routine bone scanning, liver ultrasonography and chest radiography are not indicated as part of baseline staging.

Herpes simplex virus 1 ICP27 is required for transcription of two viral late (gamma 2) genes in infected cells

The herpes simplex virus infected cell protein 27 (ICP27) is required for the expression of certain early viral proteins and for many late proteins during productive infection. Expression of at least one late (gamma 2) gene, that encoding glycoprotein C, is severely restricted in the absence of functional ICP27. The exact mode of action by which ICP27 induces late gene expression is not known, but the effect is apparent at the mRNA level as demonstrated by Northern blot analysis. To determine whether ICP27 activates late genes via transcriptional or posttranscriptional mechanisms, we initially used nuclear run-on assays to measure transcription of viral genes in Vero cells infected with wild-type (WT) virus or an ICP27 nonsense mutant virus, n504. We observed a 4-fold reduction in the nuclear run-on signal from the coding strand of the gC gene for n504-infected cells compared to that of WT-infected cells. However, interpretation of the results was complicated by the observation of a significant signal from the noncoding strand in these experiments. To obviate the problem of symmetrical transcription, we utilized in vivo RNA pulse-labeling to measure the amount of transcription of viral genes in cells infected with either WT virus or n504 virus. We found a 5- to 10-fold reduction in the transcription of the gC and U(L)47 genes, two late genes, in cells infected with n504 compared to that in cells infected with WT virus. In contrast, transcription of the ICP8 gene, an early gene, was similar in WT and n504 virus-infected cells. We also examined the stability of the gC and U(L)47 gene transcripts in n504-infected cells, and we found it to be comparable to that in WT virus-infected cells, further supporting an effect on transcription. Transcription of the gC and U(L)47 genes by n504 was normal in a cell line that expresses WT ICP27. From these results we conclude that ICP27 is required for transcription of the late gC and U(L)47 genes during productive infection.

The 2000 Canadian recommendations for the management of hypertension: Part one--therapy

OBJECTIVE

To provide updated, evidence-based recommendations for the therapy of hypertension in adults.

OPTIONS

For patients with hypertension, there are a number of lifestyle manoeuvres and antihypertensive agents that may control blood pressure. Randomized trials evaluating first- line therapy with thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors, calcium channel blockers, alpha-blockers, centrally acting agents or angiotensin II receptor antagonists were reviewed.

OUTCOMES

The health outcomes considered were changes in blood pressure, cardiovascular morbidity, and cardiovascular and/or all-cause mortality rates. Economic outcomes were not considered due to insufficient evidence.

EVIDENCE

Medline searches were conducted from the period of the last revision of the Canadian Recommendations for the Management of Hypertension (May 1998 to October 2000). Reference lists were scanned, experts were polled, and the personal files of the subgroup members and authors were used to identify other studies. All relevant articles were reviewed and appraised, using prespecified levels of evidence, by content experts and methodological experts.

VALUES

A high value was placed on the avoidance of cardiovascular morbidity and mortality.

BENEFITS, HARMS, AND COSTS

Various lifestyle manoeuvres and antihypertensive agents reduce the blood pressure of patients with sustained hypertension. In certain settings, and for specific classes of drugs, blood pressure lowering has been associated with reduced cardiovascular morbidity and/or mortality.

RECOMMENDATIONS

The present document contains detailed recommendations pertaining to all aspects of the therapy of patients with hypertension, including lifestyle modifications proven to lower blood pressure, treatment thresholds, target blood pressures, choice of agents in various settings and strategies to enhance adherence. Lower thresholds for blood pressure treatment are advocated for people with other cardiovascular risk factors or established hypertensive target organ damage. Implicit in the recommendations for therapy is the principle that treatment should be individualized for each patient and the choice of agent should be dictated by coexistent conditions. For the treatment of uncomplicated essential hypertension, thiazides, beta-adrenergic antagonists, angiotensin-converting enzyme inhibitors or calcium channel blockers may be appropriate, depending on individual circumstances.

VALIDATION

All recommendations were graded according to strength of the evidence and voted on by the Canadian Hypertension Recommendations Working Group. Only those recommendations achieving high levels of consensus are reported here. These guidelines will be updated annually.

An analogue instrument for the measurement of respiratory impedance using the forced oscillation technique

The successful development of non-invasive assisted ventilation via a nasal mask has led to the requirement for improved methods of monitoring the respiratory system. Measurements of respiratory impedance during assisted ventilation using acoustic methods are showing considerable promise in providing this clinical data. The method involves imposing very low amplitude acoustic oscillations onto the spontaneous or assisted respiratory airflow. The subsequent interaction with the respiratory system modifies the pressure and flow relationship of the forced oscillations. The ratio of pressure to flow can be used to measure in real time the absolute value of respiratory input impedance. As a result a versatile, non-invasive and repeatable profile of respiratory mechanics is obtained. Using a 5 Hz conventional forced oscillation frequency, data highly sensitive to airflow obstruction and capable of tracking mechanical events and responses become available to the clinician. Recent studies with ventilated and sleeping subjects confirm future potential for the forced oscillation technique in vivo. We describe an instrument named the respiratory impedance monitor (5 Hz), which utilizes the forced oscillation technique (FOT). This fully developed device is designed in accordance with agreed international clinical guidelines. Comparative clinical data from normal subjects and patients with chronic obstructive pulmonary disease is presented.

Identification of lysine decarboxylase as a mammalian cell growth inhibitor in Eikenella corrodens: possible role in periodontal disease

The pathogenesis of inflammatory periodontal disease was studied by examining the mechanism of HeLa and HL60 cell growth inhibition by cell-free saline-soluble extracts of Eikenella corrodens and bacterial plaque. Previous studies identified a protein (p80) as causing growth inhibition by E. corrodens extracts. After purification by two-dimensional SDS-PAGE, p80 was digested with protease lysC. Amino acid sequences were obtained and backtranslated for use as PCR primers. A 5840 nucleotide sequence containing a lysine decarboxylase gene was obtained from a Sau3 A1 genomic library of E. corrodens DNA. Lysine decarboxylase activity was present at physiologic pH in the E. corrodens extracts containing p80, and also in bacterial plaque. Both extracts caused growth inhibition by depleting lysine from cell culture media through conversion to cadaverine. Adding lysine, or immune goat IgG to a peptide derived from the active site sequence of E. corrodens lysine decarboxylase, retarded lysine depletion and growth inhibition. epsilon-Amino caproic acid specifically enhanced lysine decarboxylase activity at the low lysine concentration in HL60 cell culture media, and also increased the growth inhibition. Thus, lysine decarboxylases such as p80 inhibit growth by removing lysine from mammalian cell culture media. A new role for lysine decarboxylase activity in the microbial aetiology of periodontal disease is discussed.

What did we learn about interdisciplinary collaboration in institutions?

The Interdisciplinary Generalist Curriculum (IGC) Project significantly advanced collaboration in the development of medical school curricula. As primary care faculty began to work together they encountered and overcame many challenges inherent in this new process. Inclusion of other faculty and departments, as well as dedicated support from the deans' offices, became necessary to the success of the projects. The continuation of successful collaborative projects in the medical school environment requires a common commitment of faculty, students, department chairs, and the dean's office; protected time; and involvement of faculty from other disciplines. This article outlines initial models of collaboration implemented in the IGC Project, followed by a description of the expected and unexpected outcomes of these collaborative efforts, and a discussion of the emergence of new ways of collaborating, with recommendations for successful collaborative efforts.

The Interdisciplinary Generalist Curriculum Project at the University of Vermont College of Medicine: The Vermont Generalist Curriculum (VGC) Experience

The University of Vermont College of Medicine received its Vermont Generalist Curriculum (VGC) subcontract as one of the second-cycle Interdisciplinary Generalist Curriculum (IGC) Project schools from 1995 to 1998. The Vermont program was jointly codirected by the chairs of family practice and pediatrics and the program director for internal medicine on a rotating basis and was overseen by a multidisciplinary steering committee that included generalists, basic scientists, specialists, and students. This committee provided guidance and support in recruitment of preceptors, continuous assessment and improvement of the courses, development of a clinical correlation manual for students in clinical offices, and cooperation around a jointly sponsored annual primary care meeting that included a joint scientific program, a research forum, and a faculty development workshop. The VGC has provided a pilot for many innovative curricular changes that have served as models for the school-wide curriculum redesign process currently under way at VERMONT: While the funding for this project ended in 1998, the changes, innovations, and collaboration born out of the project are valuable enough for the dean's office to maintain the VGC's funding and its steering committee for the future.

Post hoc power analysis: an idea whose time has passed?

Using a hypothetical scenario typifying the experience that authors have when submitting manuscripts that report results of negative clinical trials, the pitfalls of a post hoc analysis are illustrated. We used the same scenario to explain how confidence intervals are used in interpreting results of clinical trials. We showed that confidence intervals better inform readers about the possibility of an inadequate sample size than do post hoc power calculations.

Mersilene mesh sling as an alternative to autogenous fascia lata in the management of ptosis

PURPOSE

To evaluate the use of Mersilene mesh as a brow suspensory material and to compare it clinically against autogenous fascia lata.

METHODS

A prospective study was carried out in which 80 eyes of 56 patients with ptosis and absent, poor or abnormal levator function were operated on. The patients were divided into two groups. In 46 eyes of 32 patients Mersilene mesh was used and in 34 eyes of 24 patients autogenous fascia lata was used. The results were recorded and analysed.

RESULTS

The age range for the Mersilene group was larger than for the fascia lata group and female patients preferred Mersilene over fascia lata. The improvement in lid height was significant in all cases in both groups. The complication rates were similar in the two groups and the mesh was well tolerated by the patients. No cases of infection, sling exposure or extrusion occurred with the use of Mersilene. Lid lag and lagophthalmos occurred as a complication of the procedure itself and not the type of the sling material. The mean follow-up period was 33.8 months for both groups.

CONCLUSION

We believe that Mersilene mesh is an effective alternative to autogenous fascia lata when the use of fascia lata is felt inappropriate.

Everyday life and legal values: a concept paper

This "concept paper" emerged from a Law and Human Behavior (LHB) Workshop, that was called by the journal's Editor, Richard Wiener, and held at St. Louis University on March 19-21, 1999. This workshop, which brought together 22 scholars and researchers in legal psychology, was part of James Ogloff's Presidential Initiative Project for the American Psychology/Law Society, and was supported by St. Louis University and an NSF grant. Prior to our arrival, each participant answered queries from the Editor about LHB and the field of psychology and law, and each was asked to offer five topics that were underrepresented in the journal or that we would like to see addressed in future issues. At the workshop, we were assigned to small groups, and the authors of this paper constituted one such group. The "charge" for all groups was to "develop plans for encouraging submissions in areas of psycholegal scholarship that continue to be infrequent topics of investigation," and then to develop a concept paper. The direction our group took is captured by our title, "Everyday Life and Legal Values," and within this paper we explicate the topic, identify a number of underrepresented research areas, suggest some research paradigms for investigating them, and present this within a "perspectival directions" frame that ties established lines of research to the newer ones we propose.

Mild head injury, anticoagulants, and risk of intracranial injury

We studied intracranial damage in patients with mild head injuries who were taking warfarin. Of the 215,785 individuals who visited the Mount Auburn and Beth Israel accident and emergency departments during our study, we identified records for 144 patients by anticoagulation status and computed tomography (CT) imaging. We retrospectively reviewed these patients and ten (7%, 95% CI 3-11) with clinically important injuries on cranial CT. Our findings suggest that patients with head injuries who receive anticoagulants have a similar or greater risk of intracranlal injury to those falling into a previously defined moderate-risk category, invalidating a previous conclusion that CT scanning is unnecessary in such patients.

Previous exposure to Chlamydia pneumoniae, Helicobacter pylori and other infections in Canadian patients with ischemic heart disease

OBJECTIVE

Previous exposures to Chlamydia pneumoniae (CP), Helicobacter pylori (HP) or cytomegalovirus (CMV) have been associated with atherosclerotic heart disease. These associations were studied in Canadian patients, and the exposure to five infections measured.

DESIGN

Case-control study.

SETTING

In the coronary care units (Hamilton General site, Henderson General site, McMaster University Medical Centre site of the Hamilton Health Sciences Corporation and St Joseph's Hospital) and from the regional angiography suite (Hamilton General site), Hamilton, Ontario.

PATIENTS AND METHODS

One hundred seven consecutive patients presenting with myocardial infarction or unstable angina (coronary care unit patients), or with previous angina or myocardial infarction (angiography suite patients), were compared with 107 family practice or outpatient clinic control subjects.

INTERVENTIONS

Cardiovascular risk factors were measured, as was serology for CP, HP, CMV, adenovirus and hepatitis A virus. Statistical analysis was by logistic regression, adjusted for age and sex.

RESULTS

Exposure to CP was more frequent in patients than in control subjects (85.4% versus 70.3%, adjusted odds ratio [OR] 2.3, 95% CI 1.1 to 5.1, P=0.03). Dividing CP immunoglobulin G absorbance into quarters, with the lowest quarter as the reference group, the adjusted ORs were 2.8, 3.0 and 4.3, respectively, for the second, third and fourth quarters (P=0.001 for trend). The seroprevalences of HP (61.7%), CMV (64.0%), adenovirus (75.6%) and hepatitis A virus (59.2%) were high, with no association with disease.

CONCLUSIONS

An association was found between heart disease and previous exposure to CP, with a stepwise increase in ORs at higher antibody levels, whereas no association was found with HP, CMV or other infections. A prospective validation of this association is needed.

Absent hematuria and expensive computerized tomography: case characteristics of emergency urolithiasis

PURPOSE

We validated the descriptive characteristics of emergency cases presenting with urolithiasis, determined the incidence of normal urinalysis in such cases and compared the expense of diagnostic computerized tomography (CT) and excretory urography (IVP).

MATERIALS AND METHODS

We retrospectively reviewed the charts of all consecutive patient visits to a community emergency department for 48 months. Explicit protocols for case selection, data abstraction and monitoring were used to maximize accuracy. Entry criteria were urolithiasis diagnosed by IVP, CT or stone passage, and urinalysis. Data analysis included descriptive statistics and the calculation of confidence intervals.

RESULTS

From 159,083 emergency visits during this period 397 met study entry criteria. Absent hematuria was noted in 9% (95% confidence interval 7% to 12%) of patients with proved urolithiasis. There was no correlation of the degree of obstruction with absent hematuria. Most patients presenting with painful urolithiasis were male (73%), in the fifth decade of life (mean age 47 years), had stones in the mid ureter (32%) or at the ureterovesicular junction (44%) and received opiates for pain control (91%). Of the patients 48% presented between 5 p.m. and 7 a.m. when the radiology department was available only for emergency imaging. The diagnosis was made by CT in half of the patients, who were charged $1,409. The maximal insurance reimbursement was $673. The diagnosis was made by IVP in half of the patients, who were charged $445. The maximal insurance reimbursement was $141.

CONCLUSIONS

Hematuria is not universally present in patients with painful urolithiasis and does not correspond to the degree of obstruction. Despite previous reports to the contrary, CT is significantly more expensive for patients than IVP.

The management of hypertension in Canada: a review of current guidelines, their shortcomings and implications for the future

Clinicians are exposed to numerous hypertension guidelines. However, their enthusiasm for these guidelines, and the impact of the guidelines, appears modest at best. Barriers to the successful implementation of a guideline can be identified at the level of the clinician, the patient or the practice setting; however, the shortcomings of the guidelines themselves have received little attention. In this paper, we review the hypertension guidelines that are most commonly encountered by Canadian clinicians: the "1999 Canadian Recommendations for the Management of Hypertension," "The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure" in the United States and the "1999 World Health Organization-International Society of Hypertension Guidelines for the Management of Hypertension." The key points of these guidelines are compared and the shortcomings that may impede their ability to influence practice are discussed. The main implications for future guideline developers are outlined.

Brinker is a sequence-specific transcriptional repressor in the Drosophila embryo

A Dpp activity gradient specifies multiple thresholds of gene expression in the dorsal ectoderm of the early embryo. Some of these thresholds depend on a putative repressor, Brinker, which is expressed in the neurogenic ectoderm in response to the maternal Dorsal gradient and Dpp signaling. Here we show that Brinker is a sequence-specific transcriptional repressor. It binds the consensus sequence, TGGCGc/tc/t, and interacts with the Groucho corepressor through a conserved sequence motif, FKPY. An optimal Brinker binding site is contained within an 800-bp enhancer from the tolloid gene, which has been identified as a genetic target of the Brinker repressor. A tolloid-lacZ transgene containing point mutations in this site exhibits an expanded pattern of expression, suggesting that Brinker directly represses tolloid transcription. We discuss other examples of transcriptional repressors constraining the activities of signaling pathways.

Topical L-ascorbic acid: percutaneous absorption studies

BACKGROUND

Reactive oxygen species generated by ultraviolet light result in photocarcinogenic and photoaging changes in the skin. Antioxidants protect skin from these insults.

OBJECTIVE

This study defines formulation characteristics for delivering L-ascorbic acid into the skin to supplement the skin's natural antioxidant reservoir.

METHODS

L-ascorbic acid or its derivatives were applied to pig skin. Skin levels of L-ascorbic acid were measured to determine percutaneous delivery.

RESULTS

L-ascorbic acid must be formulated at pH levels less than 3.5 to enter the skin. Maximal concentration for optimal percutaneous absorption was 20%. Tissue levels were saturated after three daily applications; the half-life of tissue disappearance was about 4 days. Derivatives of ascorbic acid including magnesium ascorbyl phosphate, ascorbyl-6-palmitate, and dehydroascorbic acid did not increase skin levels of L-ascorbic acid.

CONCLUSIONS

Delivery of topical L-ascorbic acid into the skin is critically dependent on formulation characteristics.

Clinical practice guidelines for the care and treatment of breast cancer: 11. Lymphedema

OBJECTIVE

To provide information and recommendations for women and their physicians when making decisions about the management of lymphedema related to breast cancer.

OPTIONS

Compression garments, pneumatic compression pumps, massage and physical therapies, other physical therapy modalities, pharmaceutical treatments.

OUTCOMES

Symptom control, quality of life, cosmetic results.

EVIDENCE

Systematic review of English-language literature retrieved primarily from MEDLINE (1966 to April 2000) and CANCERLIT (1985 to April 2000). Nonsystematic review of breast cancer literature published to October 2000.

RECOMMENDATIONS

Pre- and postoperative measurements of both arms are useful in the assessment and diagnosis of lymphedema. Circumferential measurements should be taken at 4 points: the metacarpal-phalangeal joints, the wrists, 10 cm distal to the lateral epicondyles and 15 cm proximal to the lateral epicondyles. Clinicians should elicit symptoms of heaviness, tightness or swelling in the affected arm. A difference of more than 2.0 cm at any of the 4 measurement points may warrant treatment of the lymphedema, provided that tumour involvement of the axilla or brachial plexus, infection and axillary vein thrombosis have been ruled out. Practitioners may want to encourage long-term and consistent use of compression garments by women with lymphedema. One randomized trial has demonstrated a trend in favour of pneumatic compression pumps compared with no treatment. Further randomized trials are required to determine whether pneumatic compression provides additional benefit over compression garments alone. Complex physical therapy, also called complex decongestive physiotherapy, requires further evaluation in randomized trials. In one randomized trial no difference in outcomes was detected between compression garments plus manual lymph drainage versus compression garments alone. Clinical experience supports encouraging patients to consider some practical advice regarding skin care, exercise and body weight. [A patient version of these guidelines appears in Appendix 2.]

VALIDATION

An initial draft of this document was developed by a task force sponsored by the BC Cancer Agency. It was updated and revised substantially by a writing committee and then submitted for further review, revision and approval by the Steering Committee for Clinical Practice Guidelines for the Care and Treatment of Breast Cancer.

SPONSOR

The steering committee was convened by Health Canada. COMPLETION DATE: October 2000.

The place for prescribing guidelines and the means of their dissemination

Practice guidelines are of potential benefit when a physician recognizes that they do not have all the facts required for providing appropriate health care. However, when guidelines for prescribing are known to the prescriber, and the physician chooses to modify or ignore them, their behaviour is being driven by personal and professional value systems that are in conflict with their knowledge base. Thus, providing practice guidelines to these physicians will not reduce suboptimal prescribing practices. In these circumstances, a number of studies suggest that addressing the social and situational involvement of physicians within the guidelines may enhance the promulgation and implementation of guidelines, and lead to more optimal prescribing choices for physicians.

Is it inherently prejudicial to try a juvenile as an adult?

Given only information that a youth who could have been tried as either an adult or as a juvenile was being tried as an adult for murder, 218 undergraduate mock jurors were able to form consistent impressions of the defendant. A very high percent of our mock jurors included a criminal or juvenile justice history as part of that impression. A very large majority of the mock jurors also said that knowledge of that criminal history would be relevant to their vote of guilty. Almost all mock jurors said they would be influenced toward voting guilty by knowledge of a previous criminal history. Few of the other components of the impression were so closely correlated with a judgment of relevance, or with a judgment that they would be influenced toward voting guilty by the knowledge of that component of the stereotype. The effect is relatively specific to knowledge of a previous criminal history. The study has limited ecological validity. Nonetheless, we raise questions about whether the fact that a youth is put on trial as an adult is inherently prejudicial, and violates the Sixth Amendment right to an impartial jury.

The regulation of forkhead/HNF-3beta expression in the Ciona embryo

The Ciona forkhead/HNF-3beta gene (Ci-fkh) is expressed in the primary axial tissues of the developing tadpole, including the notochord, endoderm, and rudimentary floor plate of the CNS. In an effort to determine the basis for this complex pattern of expression we have conducted a detailed analysis of the Ci-fkh 5'-regulatory region. Different 5' sequences were attached to a lacZ reporter gene and analyzed in electroporated Ciona embryos. A short regulatory sequence (AS) located approximately 1.7 kb upstream of the transcribed region is shown to be essential for expression in all three axial tissues. The proximal 20 bp of the AS contains overlapping Snail repressor elements and a T-box motif. Deleting these sequences causes the loss of reporter gene expression in the endoderm, as well as expanded expression in the neural tube. These results suggest that a T-box gene such as Ci-VegTR activates Ci-fkh expression in the endoderm, while the Ci-Sna repressor excludes expression from the lateral ependymal cells and restricts the Ci-fkh pattern to the rudimentary floor plate in ventral regions of the neural tube. We also present evidence for Ci-fkh positive autofeedback, whereby the Ci-Fkh protein binds to critical activator sites within the Ci-fkh 5'-regulatory region and helps maintain high levels of expression. We discuss these results with respect to forkhead/HNF-3beta regulation in vertebrates.

Predicting hand preference with performance on motor tasks

Handedness may be defined as preference or hand-differences in task performance. The strength and significance of the relationship between hand preference and hand performance asymmetries have been contested. To evaluate this relationship, we administered the Edinburgh Handedness Inventory and measured asymmetries in finger tapping, Purdue Pegboard, and grip strength in 30 subjects who prefer their right hand and 30 subjects who prefer their left hand. Hand asymmetries in finger tapping, Purdue Pegboard, and grip strength each predicted hand preference scores. However, a multiple regression equation best predicted hand preference by using performance of each task. Hand asymmetries in finger tapping correlated strongly with asymmetries in Purdue Pegboard performance, but neither of these asymmetries correlated strongly with asymmetries in grip strength. These findings indicate that hand preference and asymmetries in motor proficiency are strongly related, but suggest that preference and proficiency for different aspects of motor performance may be independently lateralized.

Conservation of the sequence and temporal expression of let-7 heterochronic regulatory RNA

Two small RNAs regulate the timing of Caenorhabditis elegans development. Transition from the first to the second larval stage fates requires the 22-nucleotide lin-4 RNA, and transition from late larval to adult cell fates requires the 21-nucleotide let-7 RNA. The lin-4 and let-7 RNA genes are not homologous to each other, but are each complementary to sequences in the 3' untranslated regions of a set of protein-coding target genes that are normally negatively regulated by the RNAs. Here we have detected let-7 RNAs of approximately 21 nucleotides in samples from a wide range of animal species, including vertebrate, ascidian, hemichordate, mollusc, annelid and arthropod, but not in RNAs from several cnidarian and poriferan species, Saccharomyces cerevisiae, Escherichia coli or Arabidopsis. We did not detect lin-4 RNA in these species. We found that let-7 temporal regulation is also conserved: let-7 RNA expression is first detected at late larval stages in C. elegans and Drosophila, at 48 hours after fertilization in zebrafish, and in adult stages of annelids and molluscs. The let-7 regulatory RNA may control late temporal transitions during development across animal phylogeny.

Treatment of venous thromboembolism in cancer patients

The occurrence of venous thromboembolism complicates the management of the patient with malignant disease because of the need for anticoagulant therapy. Cancer patients have an ongoing thrombotic stimulus due to the underlying cancer and its associated treatments, but are also considered to be at increased risk for anticoagulant-related bleeding. In recent years, the results of clinical trials have demonstrated the safety and efficacy of bodyweight-adjusted subcutaneous low-molecular-weight heparin administered at home for patients with acute deep vein thrombosis. This approach is particularly attractive in patients with cancer, in whom quality of life is an important consideration. There are no trials to date which specifically address the question of the duration of oral anticoagulant therapy in cancer patients. However, data can be extrapolated from trials evaluating the duration of oral anticoagulant therapy in other high-risk patients. Hence, cancer patients should continue oral anticoagulant therapy for as long the cancer remains active (usually at least 6 months). There remain a number of unanswered questions regarding the clinical management of thromboembolism in the cancer patient.

Vancomycin pharmacokinetics and Bayesian estimation in pediatric patients

The vancomycin pharmacokinetic profile was characterized in six pediatric patients and the potential of nonlinear mixed effects modeling and Bayesian forecasting for vancomycin monitoring was explored using NONMEM V (1.1). Based on steady state serial vancomycin concentrations, the estimates of mean t1/2, Vd, and Cl derived by the Sawchuk and Zaske method (1) were 3.52 hours, 0.57 L/kg, and 0.12 L/h per kg, respectively. NONMEM analysis demonstrated that a weight-adjusted two-compartment model described individual patients' data better than a comparable one-compartment model. The two-compartment estimates of mean t1/2alpha, t1/2beta, Vss, and Cl were 0.80 hour, 5.63 hours, 0.63 L/kg, and 0.11 L/h per kg, respectively. The relatively long mean t1/2alpha suggests that peak vancomycin concentrations measured earlier than 4 hours postdose do not reflect postdistributional serum concentrations. NONMEM population modeling revealed that a weight-adjusted two-compartment model provided a better fit than a comparable one-compartment model. The resulting population parameters and variances were fixed in NONMEM to obtain Bayesian predictions of individual vancomycin serum concentrations. Bayesian estimation with either a single midinterval or trough sample has the potential to provide accurate and precise predictions of vancomycin concentrations. This should be evaluated using a vancomycin population pharmacokinetic model based on a larger sample of pediatric patients.

Mental health professionals' experiences reporting suspected child abuse and maltreatment

OBJECTIVE

The purpose of this study was to provide systematic data on the experiences of mental health professionals (e.g., psychiatrists, psychologists, and social workers) who reported cases of suspected child abuse and maltreatment concerning their clients.

METHOD

Mail surveys were completed by 258 mental health professionals known to have reported a case of suspected child abuse and maltreatment to the New York State Central Register (NYSCR) in 1993. Subjects were asked to complete a survey describing their experience with making reports, referring to a specific case they reported.

RESULTS

About 40% did not inform the client about the limits of confidentiality until reportable material came up. Most clinicians reported that informing clients about the limits of confidentiality did not deter them from entering treatment. Many clinicians learned about abuse/maltreatment after approximately 3 months into therapy. Even very experienced clinicians usually consulted with others before making the report. Clinicians most typically informed the client about the report directly and before it was made, but did not call the NYSCR in the presence of the client. Following the report, most clinicians performed additional activities such as calling clients and scheduling additional sessions. When clients evidenced resistance to continuing therapy, it usually dissipated after a brief period of time. In over 72% of the cases, making the report did not disrupt the relationship and in many instances it was helpful in the therapeutic process; about 27% were continuously resistant or terminated therapy shortly after the report was made.

CONCLUSIONS

Implications for practice, training, program development, and research are discussed.

Dehydroascorbic acid transport by GLUT4 in Xenopus oocytes and isolated rat adipocytes

Dehydroascorbic acid (DHA), the first stable oxidation product of vitamin C, was transported by GLUT1 and GLUT3 in Xenopus laevis oocytes with transport rates similar to that of 2-deoxyglucose (2-DG), but due to inherent difficulties with GLUT4 expression in oocytes it was uncertain whether GLUT4 transported DHA (Rumsey, S. C. , Kwon, O., Xu, G. W., Burant, C. F., Simpson, I., and Levine, M. (1997) J. Biol. Chem. 272, 18982-18989). We therefore studied DHA and 2-DG transport in rat adipocytes, which express GLUT4. Without insulin, rat adipocytes transported 2-DG 2-3-fold faster than DHA. Preincubation with insulin (0.67 micrometer) increased transport of each substrate similarly: 7-10-fold for 2-DG and 6-8-fold for DHA. Because intracellular reduction of DHA in adipocytes was complete before and after insulin stimulation, increased transport of DHA was not explained by increased internal reduction of DHA to ascorbate. To determine apparent transport kinetics of GLUT4 for DHA, GLUT4 expression in Xenopus oocytes was reexamined. Preincubation of oocytes for >4 h with insulin (1 micrometer) augmented GLUT4 transport of 2-DG and DHA by up to 5-fold. Transport of both substrates was inhibited by cytochalasin B and displayed saturable kinetics. GLUT4 had a higher apparent transport affinity (K(m) of 0.98 versus 5.2 mm) and lower maximal transport rate (V(max) of 66 versus 880 pmol/oocyte/10 min) for DHA compared with 2-DG. The lower transport rate for DHA could not be explained by binding differences at the outer membrane face, as shown by inhibition with ethylidene glucose, or by transporter trans-activation and therefore was probably due to substrate-specific differences in transporter/substrate translocation or release. These novel data indicate that the insulin-sensitive transporter GLUT4 transports DHA in both rat adipocytes and Xenopus oocytes. Alterations of this mechanism in diabetes could have clinical implications for ascorbate utilization.

Epirubicin in breast cancer: present and future

Epirubicin, a member of the anthracycline family of chemotherapeutic agents, has been widely used throughout the world both as adjuvant therapy in early breast cancer and in metastatic breast cancer. Clinical trials with epirubicin have examined the importance of a dose-response relationship, therapeutic dose, and optimum duration of chemotherapy. In addition, pharmacokinetic studies have provided data on ideal combinations with other agents. Epirubicin-containing regimens are considered to be superior to those containing cyclophosphamide, methotrexate, and fluorouracil (CMF) and are also used in patients with locally advanced stage IIIA/IIIB breast cancer. Combinations with other chemotherapeutic agents (eg, epirubicin plus a taxane, sequential or combined use of these agents) are being evaluated in ongoing clinical trials. Moreover, recent studies have suggested that biologic markers, such as tumor HER2/neu overexpression, predict responses to dose-intensive anthracycline chemotherapy, and combinations with nonchemotherapeutic regimens (eg, trastuzumab) may provide additional benefits, but such strategies require further evaluation.

A novel process for updating recommendations for managing hypertension: rationale and methods

BACKGROUND

There are numerous hypertension consensus recommendations intended for practising physicians. However, recommendations in their current format have limited impact on improving hypertension control.

MATERIALS AND METHODS

A group of national societies, headed by the Canadian Hypertension Society, the Heart and Stroke Foundation of Canada, the Canadian Coalition for High Blood Pressure Prevention and Control, and Health Canada has developed strategies to maintain annually updated recommendations for hypertension management and to provide greater opportunities for their implementation into clinical practice. The process is overseen by a steering committee. Subcommittees have been formed for each of a list of topics seen as important to the control of hypertension. The subcommittees, with the aid of a central librarian, conduct annual literature reviews in accordance with Cochrane Collaboration strategies. Modified existing and new recommendations are forwarded to a group with expertise in clinical epidemiology. Grades of evidence are assigned to each recommendation. Revised recommendations based on the above process will be presented annually at the conjoint Canadian Hypertension Society/Canadian Cardiovascular Congress meeting. Under the leadership of the Cardiovascular Disease Division of the Laboratory Centre for Disease Control, Health Canada, a committee has been charged with the implementation process.

CONCLUSIONS

The improvements of the current process over previous national hypertension recommendations are four-fold. First, the recommendations will be updated annually. Second, the methodology has been improved. Third, the grading system can be used in the evaluation of complex study designs. Finally, the implementation process is extended. The authors are optimistic that these changes will contribute to the improvement of hypertension control in the Canadian population.

Characterization of a maternal T-Box gene in Ciona intestinalis

A new T-box gene, CiVegTR, was isolated in the ascidian Ciona intestinalis. CiVegTR maternal RNAs become localized to the vegetal cytoplasm of fertilized eggs and are incorporated into muscle lineages derived from the B4.1 blastomere. The CiVegTR protein binds to specific sequences within a minimal, 262-bp enhancer that mediates Ci-snail expression in the tail muscles. Mutations in these binding sites abolish expression from an otherwise normal lacZ reporter gene in electroporated embryos. In addition to the previously identified AC-core E-box sequences, T-box recognition sequences are conserved in the promoter regions of many genes expressed in B4.1 lineages in both Ciona and the distantly related ascidian Halocynthia. These results suggest that CiVegTR encodes a component of the classical muscle determinant that was first identified in ascidians nearly 100 years ago.