Changes in molecular weight forms of inhibin A and pro-alpha C in maternal serum during human pregnancy

Maternal serum pools obtained from healthy women throughout normal pregnancy were fractionated by a combined immunoaffinity chromatography, preparative PAGE, and electroelution procedure. Inhibin A and the pro-alpha C region of the inhibin alpha-subunit were determined in the eluted fractions by specific ELISAs, and the profiles of immunoactivity characterized in terms of molecular weight and percent recovery. The molecular weight patterns of inhibin A and pro-alpha C in serum during early pregnancy (<19 wk gestation) showed peaks between 25-40K and approximately 60K, consistent with the presence of known mature and larger precursor inhibin forms. However, during late pregnancy (>19 wk gestation), an increase in the proportion of smaller molecular weight forms (from 2% to approximately 25%) of inhibin A and pro-alpha C of unknown structure were observed in the less than 30K and less than 25K regions, respectively. To assess whether this change in molecular weight distribution in late pregnancy was related to the method of serum collection, serum and plasma from women during early and late pregnancy were collected and snap-frozen. Three pools [one from early pregnancy (12-15 wk), two from late pregnancy (28-39 wk)] of serum and plasma were then fractionated as described above. No differences in molecular weight patterns of inhibin A and pro-alpha C were observed between serum and plasma pools obtained in early pregnancy. However, in late pregnancy there was a reduction in the proportion of low molecular weight forms between serum (25% inhibin A, 35% pro-alpha C) and plasma (12% and 17%, respectively), but not to the low levels seen in early pregnancy. Incubation of iodinated 30K human inhibin A with serum or plasma obtained from early or late pregnancy showed no evidence of cleavage, suggesting that 30K inhibin A is not the cleavage precursor. It is speculated that the formation of small molecular weight forms of both inhibin A and pro-alpha C is attributed to proteolytic changes, in part induced in the circulation during late gestation and in part by the placenta before secretion. It is concluded that inhibin A and pro-alpha C are processed in late pregnancy by more than one mechanism to form low molecular weight circulating forms of unknown structure.

A streamlined process to phenotypically profile heterologous cDNAs in parallel using yeast cell-based assays

To meet the demands of developing lead drugs for the profusion of human genes being sequenced as part of the human genome project, we developed a high-throughput assay construction method in yeast. A set of optimized techniques allows us to rapidly transfer large numbers of heterologous cDNAs from nonyeast plasmids into yeast expression vectors. These high- or low-copy yeast expression plasmids are then converted quickly into integration-competent vectors for phenotypic profiling of the heterologous gene products. The process was validated first by testing proteins of diverse function, such as p38, poly(ADP-ribose) polymerase-1, and PI 3-kinase, by making active-site mutations and using existing small molecule inhibitors of these proteins. For less well-characterized genes, a novel random mutagenesis scheme was developed that allows a combination selection/screen for mutations that retain full-length expression and yet reverse a growth phenotype in yeast. A broad range of proteins in different functional classes has been profiled, with an average yield for growth interference phenotypes of approximately 30%. The ease of manipulation of the yeast genome affords us the opportunity to approach drug discovery and exploratory biology on a genomic scale and shortens assay development time significantly.

Physiological and regulatory roles of activin A in late pregnancy

Unexplained fetal death in utero in late pregnancy represents an increasing proportion of perinatal deaths. It has been assumed that critical hypoxia is the likely mechanism underlying these losses, but the lack of a physiological marker has hampered both confirmation and prediction which could lead to timely intervention. In this paper, we report studies on hypoxia that we have performed in chronically cannulated late pregnant sheep, complemented by parallel investigations undertaken in human pregnancies. Our initial studies were directed towards determining activin secretion in the fetus and mother during late gestation, and immediately after fetal surgery using a sheep model. This led us to propose that there may be a relationship between hypoxia and activin A, follistatin and prostaglandin (PG) release from the feto-placental unit. Subsequent studies have been directed towards examining this potential relationship in sheep and in humans with compromised pregnancies. As a result of these studies, we have identified a potential mechanism by which activin A may be involved in regulating the response of the fetus to hypoxic insult. Activin A and follistatin concentrations increased in late gestation in ovine maternal plasma and in fetal fluids. Feto-placental hypoxemia or maternal isocapnic hypoxemia, leading to fetal hypoxia, were specific triggers for an acute increase in fetal activin A and follistatin concentrations during late gestation. The source and secretion of activin A, follistatin, and the associated release of PGE(2,) from within the feto-placental unit varied according to the site of the insult. The concomitant secretion of activin A and PGE(2) into the fetal circulation and amniotic fluid during reduced uterine blood flow provides an insight into the physiological regulatory mechanisms that might be involved. Changes observed in maternal activin A concentrations in mid and late gestation in the human may also be associated with fetal compromise. In human pregnancies, elevated activin A concentrations were observed in maternal plasma in mid and late gestation, in association with severe pre-eclampsia and with severe fetal growth restriction, compared to those observed in pregnancies with constitutionally small, healthy fetuses. Activin A was also elevated in maternal and arterial cord plasma in women at term during labour and immediately prior to undergoing emergency Caesarean section for failure to progress. These findings offer exciting new possibilities to gain insights into the mechanisms that underlie the maintenance of fetal wellbeing and provide a rationale for the potential that activin A may prove to be a useful clinical marker of fetal distress.

Feto-placental hypoxemia regulates the release of fetal activin A and prostaglandin E(2)

The evaluation of the role of critical hypoxia in unexplained fetal death in utero has been hampered by the lack of a physiological marker. Here we report the novel observation that feto-placental hypoxemia is an acute trigger for increased activin secretion from the feto-placental unit in late pregnancy. Hypoxemia was induced in chronically cannulated late pregnant fetal sheep by restricting blood flow through the maternal uterine arteries. Using maternal and fetal blood samples and amniotic fluid obtained via chronically implanted catheters, fetal blood gas parameters, plasma and amniotic fluid concentrations of activin A, prostaglandin (PG) E(2) and PGFM, the circulating metabolite of PGF(2alpha), were determined before, during and after a ten hour period of fetal hypoxemia. Hypoxemia acutely increased activin A and PGE(2) levels in both amniotic fluid and the fetal circulation with values rapidly returning to baseline with normoxemia. PGFM also increased in both compartments with a relatively delayed time frame compared to that of activin A and PGE(2). The increase in activin A and PGE(2) induced by hypoxemia may be a mechanism to regulate feto-placental blood flow during fetal compromise and also offers the possibility that activin A represents a useful marker of feto-placental hypoxemia.

Raised maternal serum inhibin A concentration at 10 to 14 weeks of gestation is associated with pre-eclampsia

Maternal serum inhibin A and free beta human chorionic gonadotrophin (beta-hCG) were measured in 759 chromosomally normal, pregnant women at 10-14 weeks of gestation. There were nine who subsequently developed pre-eclampsia and in these women the maternal serum inhibin A concentration was significantly higher than in the normotensive controls.

Reliability, repeatability, and sensitivity of the modified shuttle test in adult cystic fibrosis

STUDY OBJECTIVES

The purpose of this study was to investigate the test-retest reliability, repeatability, and sensitivity of the modified shuttle test (MST) in adult patients with cystic fibrosis (CF).

DESIGN

: Prospective study.

SETTING

Adult CF Unit, Belfast City Hospital.

PATIENTS

: Adult patients with CF.

INTERVENTIONS

Test-retest reliability-none; sensitivity-inpatient IV antibiotic therapy for an acute exacerbation of respiratory disease.

MEASUREMENTS

The test-retest reliability and repeatability of the MST was assessed by comparing performance on two consecutive MSTs performed in 12 patients with CF and stable disease. The sensitivity of the MST was assessed by measuring the change in MST performance after 2 weeks of IV antibiotic therapy in 24 patients admitted to hospital with acute exacerbations of their respiratory disease.

RESULTS

In the assessment of test-retest reliability and repeatability (n = 12), there was a significant and strong correlation between trials for distance completed (Pearson's r = 0. 99; p < 0.01), peak heart rate (Pearson's r = 0.99; p < 0.01), peak arterial oxygen saturation (SaO(2); Pearson's r = 0.99; p < 0.01), and peak Borg rating of perceived breathlessness (Pearson's r = 0. 99; p < 0.01). The coefficients of repeatability for these variables were small (coefficient of repeatability: distance completed, 4 shuttles; peak heart rate, 6 beats/min; peak SaO(2), 4%; and peak Borg rating of perceived breathlessness, 0.9). In the assessment of sensitivity (n = 24), the standardized response mean (SRM) for distance completed on MST (SRM = 1.18) was the SRMs for spirometric measures of lung function (FEV(1), SRM = 0.96; FEV(1) percent predicted, SRM = 0.88).

CONCLUSIONS

This study demonstrates that the MST is a reliable, repeatable, and sensitive measure of exercise capacity in adult CF. The MST may be of value in determining prognosis, evaluation for lung transplantation, exercise prescription, and establishing the impact of new treatments on the disability associated with CF.

The adaptations of a quality of life questionnaire for routine use in clinical practice: the Chronic Respiratory Disease Questionnaire in cystic fibrosis

The assessment of quality of life (QoL) is necessary to monitor the course of disease and to assess the effect of new and existing interventions in clinical practice. This will only be achieved if QoL can be measured accurately and routinely. The aim of this study was to demonstrate the methodology involved in the adaptation and shortening of the Chronic Respiratory Disease Questionnaire (CRDQ) in a population of adults with cystic fibrosis (CF). A single interviewer administered the CRDQ to a sample of 45 adult patients (32 males) with CF prior to assessment of spirometric measures of lung function. Those patients whose lung function was stable at the time of study and who could attend for a retest within 14 days were asked to complete the questionnaire at a subsequent visit (n = 10). The mean interval between visits was 7 days (range 5-14 days). Correlations between spirometry and CRDQ dimensions ranged from -0.003 to 0.426. The fatigue, emotion and mastery dimensions showed high internal consistency and adequate construct validity. In the small number of patients suitable for retest, the results indicated that the dimensions exhibited adequate test-retest reliability. In contrast, low internal consistency was demonstrated for the dyspnoea dimension. The fatigue, emotion and mastery dimensions could be reduced, in terms of their number of items, without a substantial loss in explanatory power. This study suggests that QoL measurement can be made convenient and, thus, more easily accessible for routine clinical assessment.

Massive bilateral phaeochromocytomas in association with Von Hippel Lindau syndrome in pregnancy

We report a rare case of large bilateral phaeochromocytomas in pregnancy, found coincidentally by ultrasonography at 26 weeks' gestation, in a woman with a family history of Von Hippel Lindau syndrome. Further, we report maternal and fetal serum and amniotic fluid phenoxybenzamine levels from this case.

Validity of a modified shuttle test in adult cystic fibrosis

BACKGROUND

The purpose of this study was to provide some evidence of the validity of a modified shuttle test (MST) by comparing performance on the MST with peak oxygen consumption (VO2peak) measured during a treadmill test in a group of adult patients with cystic fibrosis.

METHOD

Twenty patients with stable cystic fibrosis performed a ramped maximal treadmill test (STEEP protocol) and the MST using a randomised balanced design.

RESULTS

The relationship between the distance achieved on the MST and VO2peak was strong (r = 0.95, p<0.01) with 90% of the variance in VO2peak explained by the variance in MST distance. The relationship was represented by the regression equation (with 95% confidence intervals) VO2peak = 6.83 (2.85 to 10.80) + 0.028 (0.019 to 0.024) x MST distance.

CONCLUSION

This study provides evidence of the construct validity of the MST as an objective measure of exercise capacity in adults with cystic fibrosis.

Value of C-reactive protein measurements in exacerbations of chronic obstructive pulmonary disease

C-reactive protein (CRP) has been shown to be a useful and sensitive indicator of pyogenic infections in many clinical situations, including acute pneumonia and infective pulmonary exacerbations in cystic fibrosis patients. Exacerbations of COPD are often, but not always, associated with demonstrable infection. The value of CRP measurement in this situation has not been assessed. We have evaluated CRP measurement in 50 patients [age 71 +/- 8 (SD) years] who were admitted to hospital with clinical evidence of exacerbation [PaO2 = 7.3 +/- 1.3 (SD) kPa, baseline FEV1 = 0.8 +/- 0.4 (SD) l]. These patients all had serial measurement of CRP [polarizing immunofluorescence (Abbot, TDx)], peripheral white cell count (WCC), body temperature, peak expiratory flow rate, Karnofsky performance status and chest X-ray, in addition to serial sputum bacteriological analysis carried out in a specialized laboratory. CRP was elevated (> 10 mg l-1) in all patients (n = 29) with proven infection [103 +/- 98 (SD) mg l-1]. Levels were markedly elevated in patients infected with Streptococcus pneumoniae (mean 156 mg l-1); there was also a rapid fall in the CRP with therapy. WCC fell with therapy, giving a correlation with CRP level (r = 0.44, P < 0.01). Since CRP elevation was observed in patients having exacerbation with proven infections and also in those where infection was not proven, it is possible that, while it is a marker for COPD exacerbation, it is not necessarily a marker of bacterial infection per se. However, it is evident from our study that it is of value in the assessment of exacerbations of COPD, where routine bacterial culture of sputum is often unreliable, and thus the measurement of serum CRP may provide an additional objective indicator of infection.

A population-based hepatitis B seroprevalence and risk factor study in a northern Ontario town

OBJECTIVE

To determine a) population-based hepatitis B seroprevalence rates; and b) associated behavioural risk factors.

SETTING

A remote northern Ontario town with a cluster of hepatitis B cases.

INTERVENTIONS

Anonymous blood testing linked with risk-factor questionnaires.

RESULTS

635 persons aged 14 to 30 years (51% of the eligible age cohort) donated blood in return for free vaccination; four were anti-HBs positive, and none was HBsAg positive. In all, 19% of participants reported two or more sexual partners in the previous year, 6% reported at least one tattooing in the previous year, and 1% reported illicit injection drug use. Of persons with multiple sexual partners 84% did not consistently use condoms.

CONCLUSIONS

When the serological results of the original cluster (and contacts) were considered, the age cohort's HBsAg seroprevalence rate was estimated to be between 0.24% and 0.47%. While the serosurvey did not discover additional HBsAg positive cases, there was great potential for heterosexual transmission.

A population-based hepatitis B seroprevalence and risk factor study in a northern Ontario town

OBJECTIVE

To determine a) population-based hepatitis B seroprevalence rates; and b) associated behavioural risk factors.

SETTING

A remote northern Ontario town with a cluster of hepatitis B cases.

INTERVENTIONS

Anonymous blood testing linked with risk-factor questionnaires.

RESULTS

635 persons aged 14 to 30 years (51% of the eligible age cohort) donated blood in return for free vaccination; four were anti-HBs positive, and none was HBsAg positive. In all, 19% of participants reported two or more sexual partners in the previous year, 6% reported at least one tattooing in the previous year, and 1% reported illicit injection drug use. Of persons with multiple sexual partners 84% did not consistently use condoms.

CONCLUSIONS

When the serological results of the original cluster (and contacts) were considered, the age cohort's HBsAg seroprevalence rate was estimated to be between 0.24% and 0.47%. While the serosurvey did not discover additional HBsAg positive cases, there was great potential for heterosexual transmission.

The philosophy of psychiatry: who needs it?

Many a psychiatrist has said that he did not want to burden himself with a philosophy and that this science had nothing to do with philosophy. But the exclusion of philosophy would nevertheless be disastrous for psychiatry: firstly, if we are not clearly conscious of our philosophy we shall mix it up with our scientific thinking quite unawares and bring about a scientific and philosophic confusion. Secondly, since in psychopathology in particular the scientific knowledge is not all of one kind, we have to distinguish the different modes of knowing and clarify our methods, the meaning and validity of our statements and the criteria of tests- and all this calls for philosophic logic ... To sum up: If anyone thinks he can exclude philosophy and leave it aside as useless, he will be eventually defeated by it in some obscure form or another.

Reproducibility of iodine-123-beta-CIT SPECT brain measurement of dopamine transporters

Iodine-123-beta-CIT has been used as a probe of monoamine transporters in human and nonhuman primates utilizing SPECT. To assess the utility of this tracer for measurement of striatal dopamine (DA) transporters in human disease, we studied the test/retest variability and reliability of SPECT measures obtained after bolus injection of [123I]beta-CIT 0-7 hr (Day 1) and 18-24 hr (Day 2) after administration.

METHODS

For the Day 2 study, seven healthy humans (4 men, 3 women; aged 19-74 yr) participated in two [123I]beta-CIT SPECT scans separated by 7-14 days. Subjects were imaged at 18, 21 and 24 hr postinjection of 370 MBq (10 mCi) [123I]beta-CIT. Two outcome measures were evaluated: (a) the ratio of specific striatal (activity associated with DA transporter binding) to nondisplaceable uptake, also designated V"3 and (b) the total, specific striatal uptake (%SSU) expressed as a percentage of injected radiotracer dose. Test/retest variability associated with V"3 and total specific striatal uptakes were compared for scans acquired at 18, 21 and 24 hr with 24 hr only postinjection scans. For the Day 1 study, three of the subjects participated in two kinetic studies of [123I]beta-CIT uptake. A three-compartment model was used for determination of konBmax and binding potential (BP = Bmax/Kd) and the reproducibility of the measures assessed.

RESULTS

In the Day 2 study, both outcome measures demonstrated excellent test/retest reproducibility with variability of V"3 = 6.8 +/- 6.8% and percent striatal uptake = 6.6 +/- 4.3% using data acquired from all time points. There were no significant differences in variability for the two outcome measures obtained. The intraclass correlation coefficient rho was 0.96 and 0.98 for V"3 and %SSU, respectively. Considering the 24 hr postinjection scans only, there was a nonsignificant trend toward lower test/retest variability for %SSU compared to V"3 (6.6 +/- 4.2% and 12.8 +/- 9.0%, respectively). The test/retest variability for the Day 1 kinetic modeling data showed marked differences depending on the fitting strategy and assumptions about the reversibility of [123I]beta-CIT in striatum. Using a model that assumed a low, fixed value for reversible striatal binding (k4) produced low variability (12 +/- 9%).

CONCLUSION

These data suggest that SPECT imaging performed at either 0-7 hr or 18-24 hr after [123I]beta-CIT injection permits calculation of reliable and reproducible measures of dopamine transporters and supports the feasibility of using [123I]beta-CIT in serial evaluation of human neuropsychiatric disease.

Effect of dexfenfluramine on body weight, blood pressure, insulin resistance and serum cholesterol in obese individuals

The effect of the serotonergic agent dexfenfluramine on weight loss, blood pressure, insulin sensitivity and serum lipid levels was determined in a 3-month randomised, double-blind, placebo controlled parallel design study in 50 obese subjects (body mass index 30-44 kg/m2). When compared with placebo treated patients, the dexfenfluramine group lost more weight (3.8 vs 1.1 kg, P < 0.01), had lower diastolic blood pressure (-5 vs -1.5 mmHg, P < 0.05), and lower cholesterol levels (-0.38 vs + 0.06mmol/l, P < 0.05), and showed improved insulin sensitivity (+ 11% vs + 4%, P < 0.03). Significant effects on blood pressure and insulin sensitivity were apparent after 1 week of treatment during which time weight did not change, suggesting a direct effect of the agent independent of weight loss. Dexfenfluramine thus improves a number of cardiovascular risk factors associated with obesity, with benefits additional to those achieved by weight reduction alone.

Pamidronate treatment of the neurologic sequelae of pagetic spinal stenosis

Spinal stenosis is a serious complication of Paget's disease of bone. Surgical decompression has a high complication rate and is not always effective. Medical therapy with bisphosphonates is established treatment in other forms of Paget's disease. To our knowledge, this is the first report of the use of intravenous pamidronate disodium as the sole treatment of lower limb weakness attributable to pagetic spinal stenosis. Our patient has been restored to independent living and has maintained his remission, with repeated treatment, for more than 5 years.

Age-related decline in striatal dopamine transporter binding with iodine-123-beta-CITSPECT

The effect of age on human striatal dopamine (DA) transporters was investigated with SPECT using the ligand [123I]2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane ([123I]beta-CIT).

METHODS

Iodine-123-beta-CIT binding in the striatum was examined in 28 healthy human subjects (14 men, 14 women) who ranged in age from 18 to 83 yr. Following injection with [123I]beta-CIT (mean +/- s.d. = 9.9 +/- 1.2 mCi), subjects were scanned with the brain-dedicated CERASPECT camera. A reconstructed transaxial slice 13.3-mm thick at the level of maximal striatal activity was used to determine tracer uptake in striatal and occipital regions of interest. The stability of regional uptake on Day 2 (approximately 18-24 hr postinjection) permitted estimation of the specific-to-nondisplaceable equilibrium partition coefficient: V3", calculated as (striatal--occipital)/occipital uptake at equilibrium.

RESULTS

Values of V3" ranged from 3.6 to 11.4 for this sample (6.7 +/- 1.9). V3" showed a significant inverse correlation with age (r = -0.73, n = 28, p < 0.0001). Linear regression analysis revealed that V3" declined by 51% over the age range studied or approximately 8% per decade.

CONCLUSION

These findings confirm postmortem reports of dopamine transporter loss with aging. In vivo methodologies may permit the age-related degeneration of dopamine nerve terminals to be studied in relation to the cognitive and motor deficits that occur in normal aging.

Reducing volunteer bias: using left-over specimens to estimate rates of HIV infection among inmates in Ontario, Canada

OBJECTIVE

To estimate the prevalence of HIV-1 infection among adult and young offenders admitted to remand facilities in the province of Ontario, Canada, by using a design that reduces volunteer bias.

METHODS

A study using a modified anonymous HIV-surveillance design was conducted with urine specimens routinely collected from male and female entrants to all Ontario jails, detention and youth centres between February and August 1993. Information on sex, age, and history of injecting drug use was also collected. Urine was screened using a modified commercial HIV enzyme-linked immunosorbent assay kit and confirmed using a modified in-house Western blot assay.

RESULTS

Data were obtained on 10,530 adult men, 1518 adult women, 1480 young male offenders, and 92 young female offenders. Urine specimens were available for 88% of new entrants. Of the entrants, 1% (n = 163) refused to have their urine used for research. Refusals were not associated with history of injecting drug use. Overall rates of HIV-1 infection were 1% for adult men, 1.2% for adult women, and 0% for young offenders. Both the rates of infection and prevalence of injecting drug use varied across facilities and geographic regions. Overall, 13% of adult men, 20% of adult women, 3% of young male offenders, and 2% of young female offenders reported a history of injecting drug use. Rates of infection were highest among self-reported injecting drug users. Rates of HIV were 3.6% for adult men and 4.2% for adult women who injected compared with 0.6 and 0.5%, respectively, for non-injecting drug users.

CONCLUSIONS

The use of unlinked left-over specimens is an important tool for measuring HIV-prevalence rates and should be encouraged. The results indicate that HIV rates are much higher among those entering prisons than in the general population. The pattern of HIV in Ontario prisons is similar to that reported in Europe and the United States. We are optimistic that these data will stimulate much needed efforts towards education and health promotion, and open the door to further research in Canadian prisons.