Fibroblasts modulate cardiomyocyte excitability: implications for cardiac gene therapy

In an earlier study exploring the potential of gene transfer to repair myocardial conduction defects, we observed that myotubes, generated by forced expression of MyoD, exhibit reduced excitability when also modified to express connexin43 (Cx43). We hypothesized that this effect was caused by gap junction-mediated coupling between myotubes and the underlying fibroblast feeder layer. This intriguing possibility has important implications for ongoing efforts to develop strategies for repairing myocardial conduction defects by gene transfer, and also provides novel insights into the electrophysiological function of naturally occurring heterologous cell coupling within the heart. Although a conductive function for fibroblasts through heterologous coupling has previously been reported, the current study provides novel evidence that fibroblasts can modulate cardiomyocyte excitability in a Cx43-dependent manner. In a co-culture study system, neonatal rat cardiomyocytes were grown on monolayers of mouse fibroblasts with genetically altered Cx43 expression and the effect on intrinsic beat frequency examined. Cardiomyocytes grown on wild-type (WT) fibroblasts expressing native levels of Cx43 beat significantly slower than cells grown on fibroblasts devoid of this molecule (germline knockout) or with dominant-negative functional suppression. Expression of Cx43 in fibroblasts from Cx43 knockout mice restored cardiomyocyte beat frequency, to rates comparable with those observed in co-culture with WT fibroblasts.

Increasing rates and changing patterns of hospital admissions for patients with inflammatory bowel disease in Ireland: 1996-2001

BACKGROUND

The inflammatory bowel diseases require frequent hospital visits. The literature suggests that the incidence of IBD may be increasing.

AIM

To investigate the pattern of admissions of patients with inflammatory bowel disease (IBD) to hospital over a five-year period (between 1996 and 2001).

METHODS

We obtained national data regarding admission rates for patients with IBD from the Economic and Social Research Institute (ESRI) during the years 1996 and 2001. Local data were gathered from the Hospital In-Patient Enquiry (HIPE) scheme for the same years.

RESULTS

Over this five-year period, there has been a substantial increase in the rate of admission with IBD (58% for Crohn's disease and 25% for ulcerative colitis), in particular in the number of day-case admissions for patients with Crohn's disease (125%). There has been little change in the number of patients undergoing surgery for their disease (Crohn's disease; 24% vs 20% and Ulcerative colitis; 17% vs 16.6%) and in the length of hospital stay.

CONCLUSION

Despite an increase in the rate of admission with IBD, there has been little change in the rates of surgical intervention and length of stay. The most dramatic increase was seen in the day-case admissions for patients with Crohn's disease and may reflect the use of anti-TNFalpha (infliximab) in the treatment of this disease.

Hepatitis C infection in plasmapheresis donors: an overlooked risk factor for transmission?

Hepatitis C virus infection is the leading cause of chronic liver disease worldwide and puts significant burden on health resources. Traditionally, risk factors are well recognized. Despite this, a significant percentage of people infected with hepatitis C have no identifiable mode of transmission. However, it is known that a significant number of donors at plasmapheresis have positive hepatitis C serology, thereby potentially contaminating the equipment and putting both donors and recipients at risk. Here, we describe two patients who acquired hepatitis C infection following voluntary donation at plasmapheresis abroad and suggest that this is an unusual and overlooked mode of transmission.

Survey of flexible fibreoptic bronchoscopy in the United Kingdom

The practice of flexible bronchoscopy is not standardized. Current guidelines are concerned primarily with safety aspects of the procedure. In view of this, and the authors' own observations of individual variation in preparation and technique, a national survey of bronchoscopic procedure was performed to assess physicians' methods. A structured questionnaire was mailed to 547 consultant physicians in adult respiratory medicine. Physicians' routines of patient preparation, drug therapy, sampling methods, and experience of complications with the flexible bronchoscope were assessed. A 60% response (328 physicians) was obtained. Patient consent was obtained by a junior doctor in 31% of replies. 205 (63%) physicians gave benzodiazepine sedation, 46 (14%) used opioid, and 38 (12%) administered both. Ninety-four (29%) physicians prescribed an antimuscarinic agent, and 235 (74%) gave antibiotics to patients with mechanical heart valves. Only 22% of physicians monitored electrocardiogram and 10% monitored blood pressure during all procedures. Marked variance was noted in sampling routines of suspected lung tumours. Physicians who used fluoroscopic guidance for transbronchial lung biopsy reported a significantly lower incidence of pneumothorax requiring drain insertion over the previous 12 months compared to those who did not (2.68 of 1000 versus 9.17 of 1000, (p<0.03)), but no difference in the total incidence of pneumothorax. Only 87 (27%) of responders had performed transbronchial needle aspiration sampling over the previous 12 months. The preparation and practice of flexible bronchoscopy varies greatly for each physician. Use of radiographical screening for performing transbronchial lung biopsy was associated with a lower likelihood of pneumothorax requiring chest tube drainage.

Diagnosis and treatment of Klinefelter syndrome

Many physicians underestimate the prevalence of Klinefelter syndrome and so fail to recognize its more obvious features. Increased awareness of its effects on physical, psychological, and social development should help to dispel persistent misconceptions about the condition and enable earlier diagnosis and more effective treatment.

Klinefelter syndrome

Klinefelter syndrome is the most common sex chromosome disorder. Affected males carry an additional X chromosome, which results in male hypogonadism, androgen deficiency, and impaired spermatogenesis. Some patients may exhibit all of the classic signs of this disorder, including gynecomastia, small testes, sparse body hair, tallness, and infertility, whereas others, because of the wide variability in clinical expression, lack many of these features. Treatment consists of testosterone replacement therapy to correct the androgen deficiency and to provide patients with appropriate virilization. This therapy also has positive effects on mood and self-esteem and has been shown to protect against osteoporosis, although it will not reverse infertility. Although the diagnosis of Klinefelter syndrome is now made definitively using chromosomal karyotyping, revealing in most instances a 47,XXY genotype, the diagnosis also can be made using a careful history and results of a physical examination, with the hallmark being small, firm testes. As it affects 1 in 500 male patients and presents with a variety of clinical features, primary care physicians should be familiar with this condition.

Flow cytometric DNA analyses of frozen samples from children's solid tumors

Cell ploidy and proliferative activity may be useful to clinicians in treating children with solid tumors. Frozen specimens from children with malignant solid tumors were tested at the time of diagnosis for ploidy and proliferative activity. The flow cytometric DNA histograms were examined to assess the sensitivity of the tumor cell preparation and staining method. All the frozen tumors received (n = 58), from children aged 1 mth to 17 yrs, were analyzed and included in this study. The more common tumors were neuroblastomas (n = 21) and Wilms' tumors (n = 16). The majority of tumors (91%) exhibited a diploid peak from the significant proportion of stromal/epithelial cells in the tumor specimen. The tightness of the diploid G0G1 peaks as measured by their coefficient of variations (CV) produced a mean CV of 2.43% +/- SD 0.62, range 1.3% to 4.6%. The G0G1 CVs from the aneuploid peaks had a mean of 2.34% +/- SD 0.68 with the range 0.5% to 3.7%. There was, however, a proportion of tumors (9%) which showed no normal "diploid" peak on the histogram. These tumor cell suspensions had insignificant numbers of diploid cells. Unless the position of the diploid peak could be identified on the DNA histogram the ploidy result from such tumors would be incorrect. Reference diploid cells can be added to cell suspensions prepared from frozen tumors in order to identify the position of the G0G1 peak. Reference diploid cells cannot be added to single cell preparations from paraffin embedded specimens, therefore making it impossible to define the diploid peak position in these tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

An enzyme immunoassay compared with a ligand-binding assay for measuring progesterone receptors in cytosols from breast cancers

To assay progesterone receptor (PR), we compared Abbott's enzyme immunoassay (PR-EIA) with a ligand-binding assay involving dextran-coated charcoal (PR-DCC), using cytosols prepared from 109 breast-cancer biopsies. Results by the two PR methods agreed well. Least-squares analysis produced a line of best fit having a slope of 0.88, an intercept on the PR-EIA axis of 16 fmol per milligram of protein, and a correlation coefficient (r2) of 0.87. To evaluate whether accurate PR-EIA measurements could be obtained on stored cytosols, we compared PR-EIA values for fresh cytosols with values for cytosols stored for various lengths of time up to 13 weeks. Agreement was excellent, especially when the samples showing very high binding (greater than 600 fmol per milligram of protein) were excluded. The lines of best fit after least-squares analyses of the remaining values had slopes between 1.0 and 1.1, intercepts less than 3 fmol/mg, and r2 all greater than 0.91.

An enzyme immunoassay compared with a ligand-binding assay for measuring progesterone receptors in cytosols from breast cancers

To assay progesterone receptor (PR), we compared Abbott's enzyme immunoassay (PR-EIA) with a ligand-binding assay involving dextran-coated charcoal (PR-DCC), using cytosols prepared from 109 breast-cancer biopsies. Results by the two PR methods agreed well. Least-squares analysis produced a line of best fit having a slope of 0.88, an intercept on the PR-EIA axis of 16 fmol per milligram of protein, and a correlation coefficient (r2) of 0.87. To evaluate whether accurate PR-EIA measurements could be obtained on stored cytosols, we compared PR-EIA values for fresh cytosols with values for cytosols stored for various lengths of time up to 13 weeks. Agreement was excellent, especially when the samples showing very high binding (greater than 600 fmol per milligram of protein) were excluded. The lines of best fit after least-squares analyses of the remaining values had slopes between 1.0 and 1.1, intercepts less than 3 fmol/mg, and r2 all greater than 0.91.

Influence of the menstrual cycle on the concentrations of estrogen and progesterone receptors in primary breast cancer biopsies

There is controversy in the literature regarding the effects of endogenous hormones on estrogen receptors (ER) and progesterone receptors (PR) in young women with breast cancer. We studied 117 young women with primary breast cancer and assessed their breast biopsies for ER and PR. The women had a record of their last menstrual period prior to breast biopsy. The menstrual cycle was divided into four phases--early proliferative (days 1-7), late proliferative (days 8-15), early secretory (days 16-22), and late secretory (days 23-30). There were lower levels of both ER and PR in biopsies excised during the early secretory phase than in other phases of the cycle; early proliferative phase receptor positive medians of ER = 77 fmol/mg protein and PR = 467 fmol/mg protein fell to ER = 28 fmol/mg and PR = 128 fmol/mg protein in the early secretory phase.

Comparison of an estrogen receptor related protein, the ERD5 antigen, with estrogen and progesterone receptors in breast cancer patients

Eighty five breast cancer cytosols were assessed for ERD5-antigen (an estrogen receptor associated protein) using the Amersham immunoradiometric assay. Estrogen and progesterone receptors were measured using charcoal treatment to separate receptor-bound tritiated ligand from the excess free, or weakly-bound ligand. Patients whose cytosols were receptor-rich (ER+ PR+) were more likely to be ERD5-antigen positive and had higher quantitative levels of this protein, than patients whose cytosols contained no estrogen receptor protein. However, twenty nine percent of ER-negative cytosols showed significant ERD5 antigen levels. In this preliminary study ERD5 antigen levels showed no potential value in discriminating between breast cancer cytosols from ER positive and ER negative patients.

Two aids in oestrogen receptor characterisation

1. Eighty three breast carcinoma primary and metastatic lesions were submitted for oestrogen receptor (ER) assessment using a standard dextran coated charcoal saturation analysis (0.1 nM-0.8 nM tritiated oestradiol), as well as a single saturating dose (SSD) assay (8 nM tritiated oestradiol). Excellent correlation between the two methods was demonstrated. The single dose assay also provided additional information to aid the construction of ad equate Scatchard plots in those biopsies which exhibited high levels of specific receptor proteins. 2. Three hundred and fifteen consecutive breast carcinoma primary or metastatic lesions, assessed for ER, had imprint cytological examinations to verify the malignancy of the specimen. Seven per cent demonstrated sparse epithelial cellularity with a low or nil malignant cell proportion and showed a lower receptor positivity than the remaining specimens.

Oestrogen receptors in breast cancer: greater care in collection

Care in collection, storage and transportation of breast carcinoma tissue being sent for cytoplasmic oestrogen receptor (O.R) estimations is essential. Failure to observe precise directions may lead to discrepancies that throw doubt on the accuracy of the estimation.