Transgenic and transcriptional studies on neurosecretory cell gene expression

1. Studies of the regulation of neurosecretory cell gene expression suffer from the lack of suitable cell lines. Two approaches have been used to overcome this deficit: transfection of neuropeptide genes into heterologous cell lines and generation of transgenic animals. 2. Studies with heterologous cell lines have revealed the potential involvement of nuclear hormone receptors, POU proteins, and fos/jun/ATF family members in the regulation of the vasopressin and oxytocin genes. Although limited in their scope, these studies have contributed greatly to the dissection of basic properties of elements in the vasopressin and oxytocin gene promoters. 3. Transgenic mice, and more recently rats, have been used to elucidate genomic regions governing cell specificity and physiological regulation of neurosecretory gene expression. The genes encoding the neuropeptides vasopressin and oxytocin have been used in many transgenic studies, due to the well-defined expression patterns and physiology of the endogenous neuropeptides. Cell-specific and physiologically regulated expression of these transgenes has been achieved, demonstrating the action of putative repressor elements and regulation of the expression of one gene by sequences present in the other gene. 4. Appropriate expression and translation of transgenes have resulted in the production of several useful systems. Expression of oncogene sequences in gonadotropin-releasing hormone neurons has allowed the development of cell lines from the resulting tumors, overproduction of corticotropin-releasing factor has produced animal models of anxiety and obesity, and directed ectopic expression of growth hormone has generated a potentially useful rat model of dwarfism. These and other animal models of human disease will provide important avenues for the development of therapeutic strategies.

The effects of intrahippocampal scopolamine infusions on anxiety in rats as measured by the black-white box test

Hippocampal cholinergic projections mediate attention to arousing stimuli as demonstrated by behavioral, electrophysiological, and endocrine studies. We recently reported that peripheral injections of the cholinergic antagonist scopolamine (SCOP) increased anxiety-like behaviour (ALB) in rats and we sought to investigate if this response might be hippocampally mediated. Adult male, Lister Hooded rats were implanted bilaterally with hippocampal cannulae 3 weeks prior to testing. On the test day, rats were injected with vehicle (VEH; artificial CSF at 3 microl), 15 or 30 microg SCOP, 20 min prior to being placed into the white chamber of the black-white box (n = 10/group). Rats were scored for latencies to exit and reenter the white chamber, total time spent in the white chamber, intercompartmental crossings, and activity. SCOP at 30 microg significantly reduced time to exit the white arena, while both doses of SCOP elevated latencies to reenter the white chamber. There were no effects of SCOP on intercompartmental crossing, time spent in the white chamber, or on activity levels. Loss of hippocampal cholinergic function impairs processing of threatening stimuli that manifests itself as increased ALB.

A bovine oxytocin transgene in mice: expression in the female reproductive organs and regulation during pregnancy, parturition and lactation

Transgene bovine oxytocin 3.5 (bOT3.5) consists of the bovine oxytocin structural gene flanked by 0.6 kbp of upstream and 1.9 kbp of downstream sequences. We have examined the expression of bOT3.5 in the female reproductive organs, and we show tissue-specific and physiological regulation dependent on the stage of pregnancy and lactation. In the ovary, no transgene expression could be detected during the estrus cycle, or during pregnancy. However, high levels of transgene RNA were found at day 1 of lactation. Expression dropped 10-fold by day 2 of lactation, and was undetectable thereafter. Interestingly, the expression of bOT3.5 in the mouse ovary at the beginning of lactation mimics that of the endogenous OT gene in the bovine ovary. Expression of the bOT3.5 transgene correlates with a parturition defect that results in considerable maternal mortality.

Tetracycline-regulated transgene expression in hippocampal neurones following transfection with adenoviral vectors

A transfer system that enabled the efficient introduction of transgenes into neurones and the quantitative control of the expressed transgene would greatly facilitate studies into neuronal gene function. To develop such a system we incorporated the tetracycline (Tet)-responsive On/Off regulatory elements into type-5 adenoviral (Ad) vectors. Regulation of transgene expression following transfection was measured by placing the enhanced green fluorescent protein (EGFP) gene upstream of the Tet regulatory element. The results showed that cultures of primary hippocampal cells could be transfected with very high efficiency (<70%) by the AdTet-On and AdTet-Off systems. Following transfection with the AdTet-On system no EGFP-fluorescent cells could be detected until doxycycline was added. The AdTet-Off system showed the reverse transcriptional regulation, in that the addition of Tet caused EGFP fluorescence to be abolished.

Fifteen-year experience of testicular neoplasm in a regional centre

BACKGROUND

During a 15-year period from 1980 to 1995, 63 patients from the Geelong region of Victoria presented with germ cell neoplasm.

METHODS

In this retrospective review performed by studying hospital records, treating specialists' notes and by telephone interviews, 61 of 63 patients were identified.

RESULTS

A tumour incidence of four cases per 100,000 male population per year with an overall cancer-specific survival of 95% is demonstrated. Follow-up ranged from 18 months to 15 years. The incidence of seminoma was 30%; patients with seminoma presented at a later stage than those with non-seminoma.

CONCLUSIONS

The present study demonstrates the increasing incidence of testicular tumour in the Geelong region, and the excellent prognosis of this disease with management outside of the tertiary referral centre.

A new fibre optic sensor for respiratory monitoring

A new fibre optic plethysmograph has been designed to monitor respiration non invasively. The device incorporates the idea of using thoracic and abdominal belts similar to conventional inductance plethysmography but uses an optical fibre woven into the belts rather than the usual coiled wire. The fibre optic belts incorporate a loop design in the fibre and rely on "macrobending" losses from laser light transmitted down the fibre when the bend radius of the loop changes during respiration. Changes in lung volume are monitored by analysing the relatively large resultant changes in light transmitted through the fibre. The output from the light detector has been interfaced to a computer containing a data acquisition card and the resultant intensity trace is monitored in real time using a virtual instrument created using LabVIEW graphical programming. Preliminary results suggest a highly sensitive system capable of detecting small changes in lung volume using a technique which is not susceptible to electrical noise and which is electrically safe.

Transgenic rats reveal functional conservation of regulatory controls between the Fugu isotocin and rat oxytocin genes

We have asked whether comparative genome analysis and rat transgenesis can be used to identify functional regulatory domains in the gene locus encoding the hypothalamic neuropeptides oxytocin (OT) and vasopressin. Isotocin (IT) and vasotocin (VT) are the teleost homologues of these genes. A contiguous stretch of 46 kb spanning the Fugu IT-VT locus has been sequenced, and nine putative genes were found. Unlike the OT and vasopressin genes, which are closely linked in the mammalian genome in a tail-to-tail orientation, Fugu IT and VT genes are linked head to tail and are separated by five genes. When a cosmid containing the Fugu IT-VT locus was introduced into the rat genome, we found that the Fugu IT gene was specifically expressed in rat hypothalamic oxytocinergic neurons and mimicked the response of the endogenous OT gene to an osmotic stimulus. These data show that cis-acting elements and trans-acting factors mediating the cell-specific and physiological regulation of the OT and IT genes are conserved between mammals and fish. The combination of Fugu genome analysis and transgenesis in a mammal is a powerful tool for identifying and analyzing conserved vertebrate regulatory elements.

Midterm results with the Sorin Monostrut heart valve prosthesis

OBJECTIVE

To monitor the hematological and clinical sequelae of a single tilting disc cardiac valve prosthesis.

DESIGN

Prospective nonrandomized trial.

SETTING

University teaching hospital.

PARTICIPANTS

All patients receiving a single mechanical cardiac valve prosthesis were offered the Sorin Monostrut valve if they met the criteria for valve use. Seventy-five per cent of the patients entered were in New York Heart Association (NYHA) functional class III or IV. One hundred and forty-seven patients were subsequently followed at three months and then yearly after valve implantation for seven years.

MAIN OUTCOME MEASURES

At one year, preoperative indexes of hemolysis were compared with three-month and one-year postoperative values. Actuarial curves for survival, freedom from cerebrovascular events and explantation were constructed for the seven-year follow-up period.

RESULTS

Hemolysis, as measured by lactate dehydrogenase values, commonly occurs preoperatively, remaining significantly elevated three months and one year following valve implantation. Serum haptoglobin was normal preoperatively but was significantly low at one year. Anemia was uncommon and most patients had normal reticulocyte counts at one year. At three years, 81% of patients were in NYHA functional class I.

CONCLUSIONS

Midterm results show that this valve is structurally reliable and meets all current requirements for a safe mechanical valve.

The effect of age and diet on the oral glucose tolerance test in ponies

To evaluate the effects of age and diet on the oral glucose tolerance test (OGTT) in healthy ponies, OGTTs were performed on 2 groups of British native breed ponies (Group A: 7 foals [6-9 months], Group B: 7 mature individuals [6-13 years]) when maintained on either a high fibre pelleted ration only (Groups A and B) or a hay only diet (Group B). Plasma glucose response, following oral glucose administration, for Group A (basal plasma glucose concentration [Glu0] 4.6 +/- 0.4 mmol/l (mean +/- s.d.) increasing to 11.5 +/- 1.3 mmol/l at 90 min) was significantly different (P < 0.05) from that observed for Group B (Glu0 of 4.3 +/- 0.2 mmol/l increasing to 6.8 +/- 1.3 mmol/l at 90 min), when fed the same diet. For Group B ponies, the plasma glucose response, following oral glucose administration, was significantly different (P < 0.05) when fed hay only (Glu0 4.6 +/- 0.4 mmol/l increasing to 9.6 +/- 2.1 mmol/l at 150 min) compared to when fed the high fibre pelleted ration. These results indicate that both age and diet have a significant effect on plasma glucose concentrations measured during an OGTT.

Scheduled change of antibiotic classes: a strategy to decrease the incidence of ventilator-associated pneumonia

The purpose of this study was to determine the impact of a scheduled change of antibiotic classes, used for the empiric treatment of suspected gram-negative bacterial infections, on the incidence of ventilator-associated pneumonia and nosocomial bacteremia. Six hundred eighty patients undergoing cardiac surgery were evaluated. During a 6-mo period (i.e., the before-period), our traditional practice of prescribing a third generation cephalosporin (ceftazidime) for the empiric treatment of suspected gram-negative bacterial infections was continued. This was followed by a 6-mo period (i.e., the after-period) during which a quinolone (ciprofloxacin) was used in place of the third-generation cephalosporin. The incidence of ventilator-associated pneumonia was significantly decreased in the after-period (n = 327) compared with the before-period (n = 353) (6.7 versus 11.6%; p = 0.028). This was primarily due to a significant reduction in the incidence of ventilator-associated pneumonia attributed to antibiotic-resistant gram-negative bacteria (0.9 versus 4.0%; p = 0.013). Similarly, we observed a lower incidence of bacteremia attributed to antibiotic-resistant gram-negative bacteria in the after-period compared with the before-period (0.3 versus 1.7%; p = 0.125). These data suggest that a scheduled change of antibiotic classes can reduce the incidence of ventilator-associated pneumonia attributed to antibiotic-resistant gram-negative bacteria.

Chronic debilitating fatigue in Irish general practice: a survey of general practitioners' experience

BACKGROUND

Doctors are called upon to treat chronic debilitating fatigue without the help of a protocol of care.

AIMS

To estimate the incidence of chronic debilitating fatigue in Irish general practice, to obtain information on management strategy and outcome, to explore the attitudes of practitioners (GPs) towards the concept of a chronic fatigue syndrome (CFS), and to recruit practitioners to a prospective study of chronic fatigue in primary care.

METHOD

A total of 200 names were selected from the database of the Irish College of General Practitioners (ICGP); 164 of these were eligible for the study.

RESULTS

Altogether, 118 questionnaires were returned (72%). Ninety-two (78%) responders identified cases of chronic fatigue, giving an estimated 2.1 cases per practice and an incidence of 1 per 1000 population. All social classes were represented, with a male to female ratio of 1:2. Eleven disparate approaches to treatment were advocated. Many (38%) were dissatisfied with the quality of care delivered, and 45% seldom or hardly ever referred cases for specialist opinion. The majority (58%) accepted CFS as a distinct entity, 34% were undecided, and 8% rejected it. Forty-two (35%) GPs volunteered for a prospective study.

CONCLUSION

Chronic fatigue is found in Irish general practice among patients of both sexes and all social classes. Doctors differ considerably in their management of patients and are dissatisfied with the quality of care they deliver. Many cases are not referred for specialist opinion. A prospective database is required to accurately assess the scale of this public health problem and to develop a protocol of care.

Apoptosis and other effects of radiation in normal human urothelial cells

In this paper, an attempt is made to identify endpoints that might be of potential use in the quantification of radiation effects in human tissues. Irradiated cultures of cells that are not selected for clonogenic survival but are left in situ to grow after irradiation show a wide variety of morphological and biochemical abnormalities. These include nuclear fragmentation and other evidence of programmed cell death, but they also include a considerable amount of lysis, necrosis, and persistent abnormal growth and function, which are expressed in the progeny of irradiated cells. Induction of proteins associated with stress or shock responses, growth and cell cycle control, and control of apoptosis are also seen and may persist. The dose dependence of these various responses is documented, because it probably determines to a large extent the outcome of radiation exposure in terms of whether a cell dies, divides normally, or develops genomic instability, mutation, and ultimate carcinogenic progression of the progeny. Clearly, a cell that dies presents no further threat to the organism, nor does a fully repaired cell. Therefore, a major challenge facing radiation protection research is to define the population at risk of surviving with damage. The results show that there is a variation in response to radiation between different patient cultures that is detectable in an explant culture system of primary normal human urothelium. The growth pattern and protein expression postirradiation is consistent with apoptosis being a major determinant of low dose response to radiation. This form of death appears to be suppressed at higher doses and, in the majority of subjects, results in the presence of a highly abnormal population of cells, even though the population size is the same whether their progenitors were irradiated or not.

Estimation of foetal brain dose from I-131 in the foetal thyroid

The ingestion of I-131 by pregnant women can have consequences for the developing foetus, in particular brain function. As the foetal thyroid accumulates iodine from the twelfth week of gestation onwards, the determination of foetal brain dose resulting from such I-131 accumulation is essential. Normal dosimetric methods fail to treat the case of foetus. Using an approximation method based on the MIRD approach, a foetal dose estimation scheme is developed to allow the determination of foetal brain dose from foetal thyroid irradiation. Dose values are obtained for the foetus based on the maternal intake of I-131. It was found that the choice of biokinetic model for the mother/foetus has a large impact on the determined dose estimate.

Fructosamine measurement in ponies: validation and response following experimental cyathostome infection

Validation of an assay for measurement of fructosamine in equine serum and plasma utilised blood samples collected from 24 British native breed ponies. The results indicated that fructosamine can be measured easily using an assay which is precise and accurate. Paired plasma and serum fructosamine measurements were highly correlated, however, greater variations were observed within serum compared with those in plasma. A reference range for fructosamine in plasma was calculated to be 256.9 +/- 60.6 mumol litre-1 (mean +/- 2 SD). In order to assess the fructosamine response following experimental cyathostome infection, nine British native breed ponies were allocated to one of three groups: Group 1 (3.9 million third-stage cyathostome larvae (L3) over a nine-week-period), Group 2 (3.15 million L3 over seven weeks) and Group 3 (uninfected controls). From four weeks prior to infection, blood was obtained, once weekly, from all animals for measurement of plasma fructosamine, plasma albumin and serum globulin concentrations. Plasma fructosamine concentrations decreased in all infected ponies post-infection due to enteric protein loss and/or altered protein composition and/or increased protein turnover.

The impact of nosocomial infections on patient outcomes following cardiac surgery

STUDY OBJECTIVE

To evaluate the relationship between nosocomial infections and clinical outcomes following cardiac surgery, and to identify risk factors for the development of nosocomial infections in this patient population.

DESIGN

Prospective cohort study.

SETTING

Barnes-Jewish Hospital, St. Louis, a university-affiliated teaching hospital.

PATIENTS

Six hundred five consecutive patients undergoing cardiac surgery.

INTERVENTIONS

Prospective patient surveillance and data collection.

MAIN OUTCOME MEASURES

Occurrence of nosocomial infections, multiorgan dysfunction, hospital mortality, and risk factors for the acquisition of nosocomial infections.

RESULTS

One hundred thirty-one (21.7%) patients acquired at least one nosocomial infection following cardiac surgery. Four independent risk factors for the development of a nosocomial infection were identified: the duration of mechanical ventilation, postoperative empiric antibiotic administration, the duration of urinary tract catheterization, and female gender. Thirty (5.0%) patients died during their hospitalization. The mortality rate of patients acquiring a nosocomial infection (11.5%) was significantly greater than the mortality rate of patients without a nosocomial infection (3.2%) (odds ratio [OR]=4.0; 95% confidence interval [CI]=2.7 to 5.8; p<0.001). Multiorgan dysfunction was found to be the most important independent determinant of hospital mortality (adjusted OR=23.8; 95% CI=13.5 to 42.1; p<0.001) along with the aortic cross-clamp time (adjusted OR=2.3; 95% CI=1.7 to 3.0; p=0.002) and severity of illness as measured by APACHE II (acute physiology and chronic health evaluation) (adjusted OR=1.1; 95% CI=1.1 to 1.2; p=0.019). Ventilator-associated pneumonia, clinical sepsis, female gender, the cardiopulmonary bypass time, and severity of illness were identified as independent risk factors for the development of multiorgan dysfunction. Among hospital survivors, patients acquiring a nosocomial infection had longer hospital lengths of stay compared to patients without a nosocomial infection (20.1+/-13.0 days vs 9.7+/-4.5 days; p<0.001).

CONCLUSIONS

Nosocomial infections, which are common following cardiac surgery, are associated with prolonged lengths of hospitalization, the development of multiorgan dysfunction, and increased hospital mortality. These data suggest potential interventions for the prevention of nosocomial infections following cardiac surgery that could substantially improve patient outcomes and decrease medical care costs.

Transcription of the vasoactive intestinal peptide gene in response to glucocorticoids: differential regulation of alternative transcripts is modulated by a labile protein in rat anterior pituitary

Expression of the vasoactive intestinal peptide (VIP) gene is controlled by glucocorticoids in a tissue- and endocrine status-specific manner. We have investigated the molecular mechanisms that determine glucocorticoid regulation of VIP gene expression in the rat pituitary. In initial experiments, using explant cultures of rat pituitary glands, we have demonstrated that treatment with the glucocorticoid agonist dexamethasone leads to a marked increase in VIP mRNA levels. This effect was found to be selective for the larger of two alternatively polyadenylated VIP transcripts, and in addition, protein synthesis inhibitors markedly enhanced the magnitude of this response indicating that a labile pituitary protein acts to attenuate the transcript-selective response to glucocorticoids. Nuclear run-on analysis of transcription demonstrated that the effects of dexamethasone in vitro are mediated largely, if not completely, at the level of transcription. In order to investigate the role of VIP promoter sequence in the glucocorticoid response, we then demonstrated that the activity of rat VIP gene promoter/reporter constructs in GH3 pituitary cells are up-regulated by dexamethasone. This up-regulation is virtually abolished following removal of promoter sequence between -162 and -89 of the start of transcription. Using an in vitro electrophoretic mobility shift assay, we have also demonstrated that this region of the promoter binds recombinant glucocorticoid receptor protein. The results of our study therefore indicate a direct mechanism of action for the modulation of VIP gene expression by glucocorticoids, and furthermore provide evidence of a mechanism that permits selective glucocorticoid regulation of alternative VIP transcripts.

Repression of vasopressin gene expression by glucocorticoids in transgenic mice: evidence of a direct mechanism mediated by proximal 5' flanking sequence

Glucocorticoids are known to exert multiple effects upon neuronal systems and neuronal gene expression but the molecular mechanisms through which these effects are mediated are largely undefined. In this study, a transgenic mouse model that expresses a bovine vasopressin transgene was used to investigate the mechanisms by which this neuropeptide gene is repressed by glucocorticoids. Using both northern analysis and a reverse transcriptase polymerase chain reaction assay, depletion of glucocorticoids with the 11,beta-hydroxylase inhibitor metyrapone was shown to result in a dexamethasone-reversed increase in ectopic adrenal transgene messenger RNA levels. This result shows that sequences within the confines of the 3.5 kb transgene are sufficient to mediate repression by glucocorticoids, and indicates the involvement of a type II glucocorticoid receptor mechanism which is independent of cellular context. Evidence for the involvement of cis-acting repressive elements in the proximal 5' flanking sequence was obtained in further studies in which bovine transgene constructs were shown to be negatively regulated by dexamethasone in 293 cells. The further demonstration that recombinant glucocorticoid receptor binds to a vasopressin promoter fragment in an in vitro electrophoretic mobility shift assay provided additional evidence of a direct mechanism of repression. Both in vitro studies were consistent with the presence of a glucocorticoid regulatory element within the region -300 to 155 of the transcription start site. The use of an in vivo transgenic system combined with in vitro analyses of gene promoter fragments enabled the characterization of the molecular mechanisms which effect physiological changes in vasopressin gene expression, and provided evidence of a direct mechanism of repression mediated by sequences within the vasopressin gene promoter.

The pathogenic effects of experimental cyathostome infections in ponies

Nine pony breed foals were reared indoors, then allocated to one of three groups infected with either 3.9 million (Group A) or 3.15 million (Group B) cold-conditioned third stage cyathostome larvae or kept as uninfected controls (Group C). The larvae were administered as a 'trickle' infection of 150000 larvae per dose, three times weekly. Blood biochemical and haematological analyses were performed weekly and faecal worm egg counts bi-weekly. Complete parasitological examinations were performed on all ponies at various times post-initial infection (PI): one infected animal at 9 weeks PI, four animals (three infected, one control) at 20 weeks PI and four animals (two infected, two controls) at 60-62 weeks PI. All ponies in the infected groups experienced a marked reduction in weight gain and two animals developed clinical disease: one pony developed intermittent diarrhoea and colic 8 weeks PI; another pony developed intermittent diarrhoea between 30 and 52 weeks PI. All infected ponies had decreased serum fructosamine concentrations and five had decreased serum albumin, which were first apparent 4-6 weeks PI. Alterations in the composition of serum globulins were detected in all ponies. Transient neutrophilia was observed in five animals from the infected groups 3-9 weeks PI. Serum alkaline phosphatase concentrations were increased in one pony between 30 and 60 weeks PI. During the course of the experiment, faecal samples from all infected animals were negative for worm eggs. At necropsy, cyathostome larvae were present within the mucosa of the large intestine of all infected ponies, however the mucosal larval counts varied considerably between individuals.