GATA4 sequence variants in patients with congenital heart disease

BACKGROUND

Recent reports have identified mutations in the transcription factor GATA4 in familial cases of cardiac septal defects. The prevalence of GATA4 mutations in the population of patients with septal defects is unknown. Given that patients with septal and conotruncal defect can share a common genetic basis, it is unclear whether patients with additional types of CHD might also have GATA4 mutations.

AIMS

To explore these questions by investigating a large population of 628 patients with either septal or conotruncal defects for GATA4 sequence variants.

METHODS

The GATA4 coding region and exon-intron boundaries were investigated for sequence variants using denaturing high-performance liquid chromatography or conformation-sensitive gel electrophoresis. Samples showing peak or band shifts were reamplified from genomic DNA and sequenced.

RESULTS

Four missense sequence variants (Gly93Ala, Gln316Glu, Ala411Val, Asp425Asn) were identified in five patients (two with atrial septal defect, two with ventricular septal defect and one with tetralogy of Fallot), which were not seen in a control population. All four affected amino acid residues are conserved across species, and two of the sequence variants lead to changes in polarity. Ten synonymous sequence variants were also identified in 18 patients, which were not seen in the control population.

CONCLUSIONS

These data suggest that non-synonymous GATA4 sequence variants are found in a small percentage of patients with septal defects and are very uncommonly found in patients with conotruncal defects.

Nephrotic range proteinuria in c-ANCA-positive crescentic glomerulonephritis with linear immune deposits

The three broad groups of rapidly progressing glomerulonephritis are anti glomerular basement membrane (anti-GBM) disease, renal vasculitis characterized by antineutrophil cytoplasmic antibody positivity, and a heterogeneous group with granular immune deposits. Anti-GBM disease with cytoplasmic antineutrophilic antibodies (c-ANCA) positivity (type III disease) is not known to present with nephrotic syndrome. We report here a rare presentation of nephrotic syndrome in Type III disease. Larger studies are warranted to determine whether the amount and/or type of immune deposits decide the range of proteinuria. These studies are also required to elucidate the impact of immune complex deposition on renal disease in c-ANCA-positive glomerulonephritis and to outline its pathogenetic mechanism.

Insights into the genetic basis of congenital heart disease

Cardiovascular malformations are the most common type of birth defect and result in significant mortality worldwide. The etiology for the majority of these anomalies remains unknown. Advances in the characterization of the molecular pathways critical for normal cardiac development have led to the identification of numerous genes necessary for this complex morphogenetic process. This work has aided the discovery of an increasing number of single genes being implicated as the cause of human cardiovascular malformations. This review summarizes normal cardiac development and outlines the recent discoveries of the genetic causes of congenital heart disease.

Effectiveness and tolerability of a once-daily amprenavir/ritonavir-containing highly active antiretroviral therapy regimen in antiretroviral-naïve patients at risk for nonadherence: 48-week results after 24 weeks of directly observed therapy

OBJECTIVES

To determine the safety and effectiveness of a once-daily highly active antiretroviral therapy (HAART) regimen in patients at risk for poor adherence using directly observed therapy (DOT) for 24 weeks followed by weekly phone contact for another 24 weeks.

METHODS

A prospective, open-label pilot study was carried out. Antiretroviral-naïve patients with advanced HIV disease were treated with once-daily amprenavir 1200 mg, ritonavir 200 mg, didanosine 400 mg and lamivudine 300 mg. After 24 weeks, DOT was substituted by weekly phone contact. Measurements of viral load and CD4 cell count, and safety laboratory measurements, were taken regularly for 48 weeks.

RESULTS

Twenty-two patients were enrolled in the study, of whom 19 completed at least 4 weeks of treatment. Seventeen patients completed 24 weeks and 13 completed 48 weeks. None discontinued treatment as a result of adverse events. The median baseline HIV viral load was 5.29 log(10) HIV-1 RNA copies/mL and the median CD4 cell count was 20 cells/microL. At weeks 24 and 48, 74% of the patients had viral loads <400 copies/mL. At 48 weeks, the median decrease in viral load from baseline was 3.06 log(10) copies/mL, and the median increase in CD4 cell count was 118 cells/microL. The median trough plasma amprenavir concentrations at weeks 1 and 24 were 1.87 and 1.42 microg/mL, respectively.

CONCLUSIONS

This study suggests that DOT followed by weekly patient contact results in good treatment outcome in this challenging population. The median trough plasma amprenavir concentrations were above the effective concentration of drug that resulted in 90% inhibition of viral load in vivo (EC(90)) for wild-type HIV.

A common cis-acting sequence in the DiGeorge critical region regulates bi-directional transcription of UFD1L and CDC45L

Two to three megabase deletions on chromosome 22q11 are the cytogenetic findings most commonly associated with cardiac and craniofacial defects in humans. The constellation of clinical findings associated with these deletions is termed the 22q11 deletion syndrome. We had earlier described a patient with the 22q11 deletion phenotype who was hemizygous for an atypical 20 kb microdeletion in this region. The deletion included coding regions of two genes organized head-to-head, UFD1L and CDC45L, along with an 884 bp CpG-rich intervening region. Based on this genomic organization, we hypothesized that both genes may be co-expressed and co-regulated by sequences within this region. We demonstrate that expression of both genes is enhanced in a similar pattern in precursors of structures affected by the deletion. The intergenic region is sufficient to direct transcription most strongly in the developing pharyngeal arches and limb buds of transgenic mice and can also direct bi-directional transcriptional activation in a neural crest-derived cell line. Deletion analyses revealed that a 404 bp fragment closest to UFD1L is necessary and sufficient to direct this bi-directional transcriptional activity. These results reveal the presence of a conserved regulatory region in the 22q11 deletion locus that can direct simultaneous transcription of genes involved in ubiquitin mediated protein processing (UFD1L) and cell cycle control (CDC45L).

Tbx1, a DiGeorge syndrome candidate gene, is regulated by sonic hedgehog during pharyngeal arch development

Appropriate interactions between the epithelium and adjacent neural crest-derived mesenchyme are necessary for normal pharyngeal arch development. Disruption of pharyngeal arch development in humans underlies many of the craniofacial defects observed in the 22q11.2 deletion syndrome (del22q11), but the genes responsible remain unknown. Tbx1 is a T-box transcription factor that lies in the 22q11.2 locus. Tbx1 transcripts were found to be localized to the pharyngeal endoderm and the mesodermal core of the pharyngeal arches, but were not present in the neural crest-derived mesenchyme of the pharyngeal arches. Sonic hedgehog (Shh) is also expressed in the pharyngeal arches and is necessary for normal craniofacial development. We found that Tbx1 expression was dependent upon Shh signaling in mouse embryos, consistent with their overlapping expression in the pharyngeal arches. Furthermore, Shh was sufficient to induce Tbx1 expression when misexpressed in selected regions of chick embryos. These studies reveal a Shh-mediated pathway that regulates Tbx1 during pharyngeal arch development.

A molecular pathway revealing a genetic basis for human cardiac and craniofacial defects

Microdeletions of chromosome 22q11 are the most common genetic defects associated with cardiac and craniofacial anomalies in humans. A screen for mouse genes dependent on dHAND, a transcription factor implicated in neural crest development, identified Ufd1, which maps to human 22q11 and encodes a protein involved in degradation of ubiquitinated proteins. Mouse Ufd1 was specifically expressed in most tissues affected in patients with 22q11 deletion syndrome. The human UFD1L gene was deleted in all 182 patients studied with 22q11 deletion, and a smaller deletion of approximately 20 kilobases that removed exons 1 to 3 of UFD1L was found in one individual with features typical of 22q11 deletion syndrome. These data suggest that UFD1L haploinsufficiency contributes to the congenital heart and craniofacial defects seen in 22q11 deletion.

Chlamydia trachomatis antigen in female genital tract infection

Thirty cases of female genital tract infection were investigated for the presence of Chlamydia trachomatis antigen. Endocervical swabs obtained were subjected to antigen detection by enzyme immunoassay. Rabbit antiserum to chlamydial lipopolysaccharide was used in a card test. Anti rabbit immunoglobulin G conjugated to alkaline phosphatase with a chromogenic substrate 5 bromo-4 chloro-3-indolyl phosphate and nitro blue tetrazolium were used for the enzymatic reaction. Chlamydial antigen could be detected in four out of thirty samples (13.3%). In contrast direct immunofluorescence detected 5 cases (16.6%). Although less sensitive, enzyme immunoassay can be used as a rapid diagnostic tool in detecting Chlamydia trachomatis antigen in genital infections.

Effects of indomethacin on the pharmacokinetics and pharmacodynamics of prednisolone in rats

The effect of indomethacin on the disposition of prednisolone and the induction of tyrosine aminotransferase (TAT) was examined in male Sprague-Dawley rats. Rats were pretreated with either indomethacin (5 mg/kg, intraperitoneally) or phosphate buffered saline (control) twice daily for 6 days followed by a single dose of prednisolone. Blood samples were collected after prednisolone administration. In separate animals, hepatic TAT activity (pharmacologic effect) was measured 4 h after the prednisolone dose. In addition, the effect of indomethacin on the in vitro protein binding of prednisolone was examined in pooled rat and human plasma. The clearance and apparent volume of distribution of prednisolone in the control and indomethacin-treated animals were similar, averaging 4.71 versus 4.05 L/h/kg and 1.37 versus 1.33 L/kg, respectively. The elimination half-life was 0.48 h in both groups. Indomethacin also did not affect the protein binding of prednisolone in rat or human plasma. However, indomethacin pretreatment increased the hepatic TAT activity induced by prednisolone. These studies indicate that indomethacin may affect the pharmacological effects of prednisolone without influencing its pharmacokinetics.

Effects of acute and chronic inflammation on the pharmacokinetics of prednisolone in rats

The effects of acute and chronic stages of carrageenan-induced air-pouch inflammation on the pharmacokinetics of prednisolone were studied in male Wistar rats. Chronic inflammation produced a significant increase in the area under the curve (AUC) of prednisolone compared to control animals (6594 +/- 2144 vs 3530 +/- 2164 micrograms.hr/L). The effect of acute inflammation was not significant (AUC = 4996 +/- 3813). Both acute and chronic inflammation also reduced the in vitro plasma protein binding of prednisolone, the reduction being much greater after chronic inflammation. The AUC of free prednisolone after chronic inflammation was 3141 micrograms.hr/L, compared to 1121 micrograms.hr/L in the control group and 1823 micrograms.hr/L after acute inflammation. The mean values of half-life and apparent volume of distribution at steady-state in each group were similar. These results indicate that prednisolone must be used with caution in the treatment of inflammatory diseases because of higher free concentrations of the steroid.

Bioavailability and reversible metabolism of prednisone and prednisolone in man

The pharmacokinetics of prednisone and prednisolone was examined in 12 healthy male subjects to assess the bioavailability and the parameters of reversible metabolism between the two steroids. After an oral prednisone dose of 0.8 mg kg-1 and an intravenous prednisolone dose of 0.66 mg kg-1, the bioavailability was found to be about 62%. The fraction of the dose recovered in the urine as the hydroxylated metabolites of prednisone and prednisolone was lower after the oral prednisone dose, suggesting that poor absorption of prednisone was the main cause of the low bioavailability. There was a high degree of interconversion between prednisone and prednisolone with 76% of the dose being recycled. The formation clearance of prednisolone from prednisone is much greater than the formation clearance of prednisone from prednisolone or the irreversible elimination clearances of the two steroids. The possible dose dependences of bioavailability and interconversion may be important factors in prednisolone therapy.

Comparison of four basic models of indirect pharmacodynamic responses

Four basic models for characterizing indirect pharmacodynamic responses after drug administration have been developed and compared. The models are based on drug effects (inhibition or stimulation) on the factors controlling either the input or the dissipation of drug response. Pharmacokinetic parameters of methylprednisolone were used to generate plasma concentration and response-time profiles using computer simulations. It was found that the responses produced showed a slow onset and a slow return to baseline. The time of maximal response was dependent on the model and dose. In each case, hysteresis plots showed that drug concentrations preceded the response. When the responses were fitted with pharmacodynamic models based on distribution to a hypothetical effect compartment, the resulting parameters were dose-dependent and inferred biological implausibility. Indirect response models must be treated as distinct from conventional pharmacodynamic models which assume direct action of drugs. The assumptions, equations, and data patterns for the four basic indirect response models provide a starting point for evaluation of pharmacologic effects where the site of action precedes or follows the measured response variable.

Perinatal ovarian cyst: a nonsurgical approach

A case of an ovarian cyst diagnosed antenatally by ultrasound and showing spontaneous resolution within 5 months after birth is presented. On the basis of this case and others reported in the literature, we recommend expectant follow-up of such lesions with operation recommended only for cysts with solid or complex components or cysts causing symptoms from large size or torsion.

Effect of the anti-inflammatory agent tenidap on the pharmacokinetics and pharmacodynamics of prednisolone

The effect of tenidap, a new nonsteroidal anti-inflammatory agent, on the pharmacokinetics and pharmacodynamics of prednisolone was studied in healthy male subjects. In a randomized crossover study, 12 subjects received either tenidap sodium 120 mg daily or placebo orally for 28 days. On day 21, each subject received a single dose of either 0.8 mg/kg oral prednisone or 0.66 mg/kg intravenous prednisolone followed by the other steroid on day 28. Blood and urine samples were collected, and the pharmacokinetic parameters of prednisone and prednisolone were determined in each treatment period. Pretreatment with tenidap did not cause any significant changes in the overall disposition of prednisone or prednisolone. For example, for free prednisolone, the intravenous area under concentration was 1,144 +/- 195 ng.h/mL and 1,244 +/- 140 ng.h/mL, and the systemic availability after oral prednisone was 53 +/- 10% and 51 +/- 12% with placebo and tenidap, respectively. The renal clearance of prednisolone was significantly reduced after tenidap pretreatment, however (from 143 to 77 mL/min/1.73 m2). The suppression of plasma cortisol and whole blood histamine levels were analyzed to evaluate the potential pharmacodynamic interactions between tenidap and prednisolone. There were no significant changes in the pharmacodynamic parameters between placebo and tenidap groups. The excretion of less than 20% of the dose of prednisolone in urine makes the overall effects of tenidap on prednisolone kinetics and dynamics of inconsequential clinical importance.

Simultaneous analysis of prednisone, prednisolone and their major hydroxylated metabolites in urine by high-performance liquid chromatography

A high-performance liquid chromatographic technique for the simultaneous determination of prednisone, prednisolone and their major hydroxylated metabolites, viz., 20 beta-hydroxyprednisone, 6 beta-, 20 alpha- and 20 beta-hydroxyprednisolone, in human urine is presented. The retention times were 6.5, 11.4, 18.1, 24.2, 31.6 and 35.3 min, respectively. The technique employs betamethasone as the internal standard. Samples are extracted with ethyl acetate using a diatomaceous earth extraction column, and the extract was dried and injected onto a silica gel column with ultraviolet detection at 254 nm. The calibration curve is linear within the studied range 50-1500 ng/ml for prednisolone and 50-750 ng ml for the other steroids. The intra-day and inter-day coefficients of variation are less than 10% for prednisone and prednisolone but higher for the metabolites. The assay was used to study the excretion rate profile of each of these steroids in the urine of a normal male subject receiving a 49.3-mg intravenous dose of prednisolone. The results indicate that prednisone, 6 beta-, 20 alpha- and 20 beta-hydroxyprednisolone may be the major unconjugated metabolites of prednisolone while 20 beta-hydroxyprednisone may be a minor metabolite.

Effect of diet and weight reduction in hypertension

Weight reduction by a low-energy diet and a high-polyunsaturates-, fiber- and potassium-rich diet may be independently useful to hypertensives. To study the effect of such diets, 416 hypertensives were randomized to either a low-energy cardiovasoprotective (CVP) diet (Group A; n = 106), a low-energy usual diet (Group B; n = 104), an optimal-energy CVP diet (Group C; n = 104), or an optimal-energy, usual pre-experimental diet (Group D; n = 102) plus drug therapy in a single-blind and controlled fashion. Groups A and B received significant (p less than 0.02) fewer calories per day than Groups C and D. Groups A and C also received significantly (p less than 0.02) more calories per amount of complex carbohydrates, polyunsaturates, potassium, and magnesium than did Groups B and D. Dietary compliance and drug intake was checked weekly. After 3 months, there was a significant fall in mean serum cholesterol (p less than 0.01) and mean serum triglycerides (p less than 0.05) in Group A compared with Group D. Group A and B patients had a loss of around 10kg of mean body weight, with no weight change seen in Group D. Weight loss was associated with a significant fall in systolic and diastolic pressures in both Group A (22/18mmHg) and Group B (16/13mmHg) compared with Group D at the end of the study. Group C patients also showed a significant fall in pressure (13/10mmHg) compared with Group D. Drug therapy, exercise, and salt intake were similar in all the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Radioiodide uptake and turnover in a pseudo-medullary thyroid carcinoma

A mass in a woman's neck, with no sequestration by Tc-99m imaging, was accompanied by an elevated serum calcitonin on one occasion. Light microscopy of a biopsy was consistent with medullary thyroid carcinoma. Electron microscopy showed secretory granules similar to those found in normal C-cells and in medullary carcinoma of the thyroid. The neck mass (and pulmonary and hepatic metastases likely from the principal mass) concentrated radioiodide (I-131). Subsequent immunoperoxidase examination of the tissues showed them to contain thyroglobulin but not calcitonin. The tumor was thus likely of follicular-cell origin. Reports of radioiodide uptake in medullary thyroid carcinoma may be correct, but each case will have to be re-examined with attention to tissue markers such as thyroglobulin and calcitonin. These markers might more correctly classify the origin of the tumor. The possibilities of cell interconversion and of dual origin are also discussed. Whole-body turnover of radioiodide was quantified as well as that in the pulmonary lesions. Rapid removal of radioactivity was present, suggesting that agents reducing iodide turnover might have therapeutic value in these cases. At five days after radioiodide administration, a biopsy specimen showed that the tumor-to-blood ratio (per gram) was greater than 1.