IFT74 variants cause skeletal ciliopathy and motile cilia defects in mice and humans

Motile and non-motile cilia play critical roles in mammalian development and health. These organelles are composed of a 1000 or more unique proteins, but their assembly depends entirely on proteins synthesized in the cell body and transported into the cilium by intraflagellar transport (IFT). In mammals, malfunction of non-motile cilia due to IFT dysfunction results in complex developmental phenotypes that affect most organs. In contrast, disruption of motile cilia function causes subfertility, disruption of the left-right body axis, and recurrent airway infections with progressive lung damage. In this work, we characterize allele specific phenotypes resulting from IFT74 dysfunction in human and mice. We identified two families carrying a deletion encompassing IFT74 exon 2, the first coding exon, resulting in a protein lacking the first 40 amino acids and two individuals carrying biallelic splice site mutations. Homozygous exon 2 deletion cases presented a ciliary chondrodysplasia with narrow thorax and progressive growth retardation along with a mucociliary clearance disorder phenotype with severely shorted cilia. Splice site variants resulted in a lethal skeletal chondrodysplasia phenotype. In mice, removal of the first 40 amino acids likewise results in a motile cilia phenotype but with little effect on primary cilia structure. Mice carrying this allele are born alive but are growth restricted and developed hydrocephaly in the first month of life. In contrast, a strong, likely null, allele of Ift74 in mouse completely blocks ciliary assembly and causes severe heart defects and midgestational lethality. In vitro studies suggest that the first 40 amino acids of IFT74 are dispensable for binding of other IFT subunits but are important for tubulin binding. Higher demands on tubulin transport in motile cilia compared to primary cilia resulting from increased mechanical stress and repair needs could account for the motile cilia phenotype observed in human and mice.

Spatial transcriptome profiling uncovers metabolic regulation of left-right patterning

Left-right patterning disturbance can cause severe birth defects, but it remains least understood of the three body axes. We uncovered an unexpected role for metabolic regulation in left-right patterning. Analysis of the first spatial transcriptome profile of left-right patterning revealed global activation of glycolysis, accompanied by right-sided expression of Bmp7 and genes regulating insulin growth factor signaling. Cardiomyocyte differentiation was left-biased, which may underlie the specification of heart looping orientation. This is consistent with known Bmp7 stimulation of glycolysis and glycolysis suppression of cardiomyocyte differentiation. Liver/lung laterality may be specified via similar metabolic regulation of endoderm differentiation. Myo1d , found to be left-sided, was shown to regulate gut looping in mice, zebrafish, and human. Together these findings indicate metabolic regulation of left-right patterning. This could underlie high incidence of heterotaxy-related birth defects in maternal diabetes, and the association of PFKP, allosteric enzyme regulating glycolysis, with heterotaxy. This transcriptome dataset will be invaluable for interrogating birth defects involving laterality disturbance.

IFT74 variants cause skeletal ciliopathy and motile cilia defects in mice and humans

Motile and non-motile cilia are critical to mammalian development and health. Assembly of these organelles depends on proteins synthesized in the cell body and transported into the cilium by intraflagellar transport (IFT). A series of human and mouse IFT74 variants were studied to understand the function of this IFT subunit. Humans missing exon 2, which codes for the first 40 residues, presented an unusual combination of ciliary chondrodysplasia and mucociliary clearance disorders while individuals carrying biallelic splice site variants developed a lethal skeletal chondrodysplasia. In mice, variants thought to remove all Ift74 function, completely block ciliary assembly and result in midgestational lethality. A mouse allele that removes the first 40 amino acids, analogous to the human exon 2 deletion, results in a motile cilia phenotype with mild skeletal abnormalities. In vitro studies suggest that the first 40 amino acids of IFT74 are dispensable for binding of other IFT subunits but are important for tubulin binding. Higher demands on tubulin transport in motile cilia compared to primary cilia could account for the motile cilia phenotype observed in human and mice.

Genetic resiliency associated with dominant lethal TPM1 mutation causing atrial septal defect with high heritability

Analysis of large-scale human genomic data has yielded unexplained mutations known to cause severe disease in healthy individuals. Here, we report the unexpected recovery of a rare dominant lethal mutation in TPM1, a sarcomeric actin-binding protein, in eight individuals with large atrial septal defect (ASD) in a five-generation pedigree. Mice with Tpm1 mutation exhibit early embryonic lethality with disrupted myofibril assembly and no heartbeat. However, patient-induced pluripotent-stem-cell-derived cardiomyocytes show normal beating with mild myofilament defect, indicating disease suppression. A variant in TLN2, another myofilament actin-binding protein, is identified as a candidate suppressor. Mouse CRISPR knock-in (KI) of both the TLN2 and TPM1 variants rescues heart beating, with near-term fetuses exhibiting large ASD. Thus, the role of TPM1 in ASD pathogenesis unfolds with suppression of its embryonic lethality by protective TLN2 variant. These findings provide evidence that genetic resiliency can arise with genetic suppression of a deleterious mutation.

Inhibition of translation initiation factor eIF4a inactivates heat shock factor 1 (HSF1) and exerts anti-leukemia activity in AML

Eukaryotic initiation factor 4A (eIF4A), the enzymatic core of the eIF4F complex essential for translation initiation, plays a key role in the oncogenic reprogramming of protein synthesis, and thus is a putative therapeutic target in cancer. As important component of its anticancer activity, inhibition of translation initiation can alleviate oncogenic activation of HSF1, a stress-inducible transcription factor that enables cancer cell growth and survival. Here, we show that primary acute myeloid leukemia (AML) cells exhibit the highest transcript levels of eIF4A1 compared to other cancer types. eIF4A inhibition by the potent and specific compound rohinitib (RHT) inactivated HSF1 in these cells, and exerted pronounced in vitro and in vivo anti-leukemia effects against progenitor and leukemia-initiating cells, especially those with FLT3-internal tandem duplication (ITD). In addition to its own anti-leukemic activity, genetic knockdown of HSF1 also sensitized FLT3-mutant AML cells to clinical FLT3 inhibitors, and this synergy was conserved in FLT3 double-mutant cells carrying both ITD and tyrosine kinase domain mutations. Consistently, the combination of RHT and FLT3 inhibitors was highly synergistic in primary FLT3-mutated AML cells. Our results provide a novel therapeutic rationale for co-targeting eIF4A and FLT3 to address the clinical challenge of treating FLT3-mutant AML.

Common deletion variants causing protocadherin-α deficiency contribute to the complex genetics of BAV and left-sided congenital heart disease

Bicuspid aortic valve (BAV) with ~1%-2% prevalence is the most common congenital heart defect (CHD). It frequently results in valve disease and aorta dilation and is a major cause of adult cardiac surgery. BAV is genetically linked to rare left-heart obstructions (left ventricular outflow tract obstructions [LVOTOs]), including hypoplastic left heart syndrome (HLHS) and coarctation of the aorta (CoA). Mouse and human studies indicate LVOTO is genetically heterogeneous with a complex genetic etiology. Homozygous mutation in the Pcdha protocadherin gene cluster in mice can cause BAV, and also HLHS and other LVOTO phenotypes when accompanied by a second mutation. Here we show two common deletion copy number variants (delCNVs) within the PCDHA gene cluster are associated with LVOTO. Analysis of 1,218 white individuals with LVOTO versus 463 disease-free local control individuals yielded odds ratios (ORs) at 1.47 (95% confidence interval [CI], 1.13-1.92; p = 4.2 × 10-3) for LVOTO, 1.47 (95% CI, 1.10-1.97; p = 0.01) for BAV, 6.13 (95% CI, 2.75-13.7; p = 9.7 × 10-6) for CoA, and 1.49 (95% CI, 1.07-2.08; p = 0.019) for HLHS. Increased OR was observed for all LVOTO phenotypes in homozygous or compound heterozygous PCDHA delCNV genotype comparison versus wild type. Analysis of an independent white cohort (381 affected individuals, 1,352 control individuals) replicated the PCDHA delCNV association with LVOTO. Generalizability of these findings is suggested by similar observations in Black and Chinese individuals with LVOTO. Analysis of Pcdha mutant mice showed reduced PCDHA expression at regions of cell-cell contact in aortic smooth muscle and cushion mesenchyme, suggesting potential mechanisms for BAV pathogenesis and aortopathy. Together, these findings indicate common variants causing PCDHA deficiency play a significant role in the genetic etiology of common and rare LVOTO-CHD.

Cardiovascular Development and Congenital Heart Disease Modeling in the Pig

Background

Modeling cardiovascular diseases in mice has provided invaluable insights into the cause of congenital heart disease. However, the small size of the mouse heart has precluded translational studies. Given current high‐efficiency gene editing, congenital heart disease modeling in other species is possible. The pig is advantageous given its cardiac anatomy, physiology, and size are similar to human infants. We profiled pig cardiovascular development and generated genetically edited pigs with congenital heart defects.

Methods and Results

Pig conceptuses and fetuses were collected spanning 7 stages (day 20 to birth at day 115), with at least 3 embryos analyzed per stage. A combination of magnetic resonance imaging and 3‐dimensional histological reconstructions with episcopic confocal microscopy were conducted. Gross dissections were performed in late‐stage or term fetuses by using sequential segmental analysis of the atrial, ventricular, and arterial segments. At day 20, the heart has looped, forming a common atria and ventricle and an undivided outflow tract. Cardiac morphogenesis progressed rapidly, with atrial and outflow septation evident by day 26 and ventricular septation completed by day 30. The outflow and atrioventricular cushions seen at day 20 undergo remodeling to form mature valves, a process continuing beyond day 42. Genetically edited pigs generated with mutation in chromatin modifier SAP130 exhibited tricuspid dysplasia, with tricuspid atresia associated with early embryonic lethality.

Conclusions

The major events in pig cardiac morphogenesis are largely complete by day 30. The developmental profile is similar to human and mouse, indicating gene edited pigs may provide new opportunities for preclinical studies focused on outcome improvements for congenital heart disease.

A Membrane-Tethered Ubiquitination Pathway Regulates Hedgehog Signaling and Heart Development

The etiology of congenital heart defects (CHDs), which are among the most common human birth defects, is poorly understood because of its complex genetic architecture. Here, we show that two genes implicated in CHDs, Megf8 and Mgrn1, interact genetically and biochemically to regulate the strength of Hedgehog signaling in target cells. MEGF8, a transmembrane protein, and MGRN1, a RING superfamily E3 ligase, assemble to form a receptor-like ubiquitin ligase complex that catalyzes the ubiquitination and degradation of the Hedgehog pathway transducer Smoothened. Homozygous Megf8 and Mgrn1 mutations increased Smoothened abundance and elevated sensitivity to Hedgehog ligands. While mice heterozygous for loss-of-function Megf8 or Mgrn1 mutations were normal, double heterozygous embryos exhibited an incompletely penetrant syndrome of CHDs with heterotaxy. Thus, genetic interactions can arise from biochemical mechanisms that calibrate morphogen signaling strength, a conclusion broadly relevant for the many human diseases in which oligogenic inheritance is emerging as a mechanism for heritability.

Simplified Luminal Water Imaging for the Detection of Prostate Cancer From Multiecho T2 MR Images

BACKGROUND

Luminal water imaging (LWI) suffers less from imaging artifacts than the diffusion-weighted imaging used in multiparametric MRI of the prostate. LWI obtains multicompartment tissue information from a multiecho T2 dataset.

PURPOSE

To compare a simplified LWI technique with apparent diffusion coefficient (ADC) in classifying lesions based on groupings of PI-RADS v2 scores. Secondary aims were to investigate whether LWI differentiates between histologically confirmed tumor and normal tissue as effectively as ADC, and whether LWI is correlated with the multicompartment parameters of the vascular, extracellular, and restricted diffusion for cytometry in tumors (VERDICT) diffusion model.

STUDY TYPE

A subset of a larger prospective study.

POPULATION

In all, 65 male patients aged 49-79 were scanned.

FIELD STRENGTH/SEQUENCE

A 32-echo T2 and a six b-value diffusion sequence (0, 90, 500, 1500, 2000, 3000 s/mm2 ) at 3T.

ASSESSMENT

Regions of interest were placed by a board-certified radiologist in areas of lesion and benign tissue and given PI-RADS v2 scores.

STATISTICAL TESTS

Receiver operating characteristic and logistic regression analyses were performed.

RESULTS

LWI classifies tissue as PI-RADS 1,2 or PI-RADS 3,4,5 with an area under curve (AUC) value of 0.779, compared with 0.764 for ADC. LWI differentiated histologically confirmed malignant from nonmalignant tissue with AUC, sensitivity, and specificity values of 0.81, 75%, and 87%, compared with 0.75, 83%, and 67% for ADC. The microstructural basis of the LWI technique is further suggested by the correspondence with the VERDICT diffusion-based microstructural imaging technique, with α, A1 , A2 , and LWF showing significant correlations.

DATA CONCLUSION

LWI alone can predict PI-RADS v2 score groupings and detect histologically confirmed tumors with an ability similar to ADC alone without the limitations of diffusion-weighted MRI. This is important, given that ADC has an advantage in these tests as it already informs PI-RADS v2 scoring. LWI also provides multicompartment information that has an explicit biophysical interpretation, unlike ADC.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:910-917.

Airway ciliary dysfunction and respiratory symptoms in patients with transposition of the great arteries

BACKGROUND

Our prior work on congenital heart disease (CHD) with heterotaxy, a birth defect involving randomized left-right patterning, has shown an association of a high prevalence of airway ciliary dysfunction (CD; 18/43 or 42%) with increased respiratory symptoms. Furthermore, heterotaxy patients with ciliary dysfunction were shown to have more postsurgical pulmonary morbidities. These findings are likely a reflection of the common role of motile cilia in both airway clearance and left-right patterning. As CHD comprising transposition of the great arteries (TGA) is commonly thought to involve disturbance of left-right patterning, especially L-TGA with left-right ventricular inversion, we hypothesize CHD patients with transposition of great arteries (TGA) may have high prevalence of airway CD with increased respiratory symptoms.

METHODS AND RESULTS

We recruited 75 CHD patients with isolated TGA, 28% L and 72% D-TGA. Patients were assessed using two tests typically used for evaluating airway ciliary dysfunction in patients with primary ciliary dyskinesia (PCD), a recessive sinopulmonary disease caused by respiratory ciliary dysfunction. This entailed the measurement of nasal nitric oxide (nNO), which is typically low with PCD. We also obtained nasal scrapes and conducted videomicroscopy to assess respiratory ciliary motion (CM). We observed low nNO in 29% of the patients, and abnormal CM in 57%, with 22% showing both low nNO and abnormal CM. No difference was observed for the prevalence of either low nNO or abnormal ciliary motion between patients with D vs. L-TGA. Respiratory symptoms were increased with abnormal CM, but not low nNO. Sequencing analysis showed no compound heterozygous or homozygous mutations in 39 genes known to cause PCD, nor in CFTR, gene causing cystic fibrosis. As both are recessive disorders, these results indicate TGA patients with ciliary dysfunction do not have PCD or cystic fibrosis (which can cause low nNO or abnormal ciliary motion).

CONCLUSIONS

TGA patients have high prevalence of abnormal CM and low nNO, but ciliary dysfunction was not correlated with TGA type. Differing from PCD, respiratory symptoms were increased with abnormal CM, but not low nNO. Together with the negative findings from exome sequencing analysis, this would suggest TGA patients with ciliary dysfunction do not have PCD but nevertheless may suffer from milder airway clearance deficiency. Further studies are needed to investigate whether such ciliary dysfunction is associated with increased postsurgical complications as previously observed in CHD patients with heterotaxy.

Antiparasitic Lead Discovery: Toward Optimization of a Chemotype with Activity Against Multiple Protozoan Parasites

Human African trypanosomiasis (HAT), Chagas disease, and leishmaniasis present a significant burden across the developing world. Existing therapeutics for these protozoal neglected tropical diseases suffer from severe side effects and toxicity. Previously, NEU-1045 (3) was identified as a promising lead with cross-pathogen activity, though it possessed poor physicochemical properties. We have designed a library of analogues with improved calculated physicochemical properties built on the quinoline scaffold of 3 incorporating small, polar aminoheterocycles in place of the 4-(3-fluorobenzyloxy)aniline substituent. We report the biological activity of these inhibitors against Trypanosoma brucei (HAT), T. cruzi (Chagas disease), and Leishmania major (cutaneous leishmaniasis) and describe the identification of N-(5-chloropyrimidin-2-yl)-6-(4-(morpholinosulfonyl)phenyl)quinolin-4-amine (13t) as a promising inhibitor of L. major proliferation and 6-(4-(morpholinosulfonyl)phenyl)-N-(pyrimidin-4-yl)quinolin-4-amine (13j), a potent inhibitor of T. brucei proliferation with improved drug-like properties.

Brain Dysplasia Associated with Ciliary Dysfunction in Infants with Congenital Heart Disease

OBJECTIVE

To test for associations between abnormal respiratory ciliary motion (CM) and brain abnormalities in infants with congenital heart disease (CHD) STUDY DESIGN: We recruited 35 infants with CHD preoperatively and performed nasal tissue biopsy to assess respiratory CM by videomicroscopy. Cranial ultrasound scan and brain magnetic resonance imaging were obtained pre- and/or postoperatively and systematically reviewed for brain abnormalities. Segmentation was used to quantitate cerebrospinal fluid and regional brain volumes. Perinatal and perioperative clinical variables were collected.

RESULTS

A total of 10 (28.5%) patients with CHD had abnormal CM. Abnormal CM was not associated with brain injury but was correlated with increased extraaxial cerebrospinal fluid volume (P < .001), delayed brain maturation (P < .05), and a spectrum of subtle dysplasia including the hippocampus (P < .0078) and olfactory bulb (P < .034). Abnormal CM was associated with higher composite dysplasia score (P < .001), and both were correlated with elevated preoperative serum lactate (P < .001).

CONCLUSIONS

Abnormal respiratory CM in infants with CHD is associated with a spectrum of brain dysplasia. These findings suggest that ciliary defects may play a role in brain dysplasia in patients with CHD and have the potential to prognosticate neurodevelopmental risks.

Genetic link between renal birth defects and congenital heart disease

Structural birth defects in the kidney and urinary tract are observed in 0.5% of live births and are a major cause of end-stage renal disease, but their genetic aetiology is not well understood. Here we analyse 135 lines of mice identified in large-scale mouse mutagenesis screen and show that 29% of mutations causing congenital heart disease (CHD) also cause renal anomalies. The renal anomalies included duplex and multiplex kidneys, renal agenesis, hydronephrosis and cystic kidney disease. To assess the clinical relevance of these findings, we examined patients with CHD and observed a 30% co-occurrence of renal anomalies of a similar spectrum. Together, these findings demonstrate a common shared genetic aetiology for CHD and renal anomalies, indicating that CHD patients are at increased risk for complications from renal anomalies. This collection of mutant mouse models provides a resource for further studies to elucidate the developmental link between renal anomalies and CHD.

Protozoan Parasite Growth Inhibitors Discovered by Cross-Screening Yield Potent Scaffolds for Lead Discovery

Tropical protozoal infections are a significant cause of morbidity and mortality worldwide; four in particular (human African trypanosomiasis (HAT), Chagas disease, cutaneous leishmaniasis, and malaria) have an estimated combined burden of over 87 million disability-adjusted life years. New drugs are needed for each of these diseases. Building on the previous identification of NEU-617 (1) as a potent and nontoxic inhibitor of proliferation for the HAT pathogen (Trypanosoma brucei), we have now tested this class of analogs against other protozoal species: T. cruzi (Chagas disease), Leishmania major (cutaneous leishmaniasis), and Plasmodium falciparum (malaria). Based on hits identified in this screening campaign, we describe the preparation of several replacements for the quinazoline scaffold and report these inhibitors’ biological activities against these parasites. In doing this, we have identified several potent proliferation inhibitors for each pathogen, such as 4-((3-chloro-4-((3-fluorobenzyl)oxy)phenyl)amino)-6-(4-((4-methyl-1,4-diazepan-1-yl)sulfonyl)phenyl)quinoline-3-carbonitrile (NEU-924, 83) for T. cruzi and N-(3-chloro-4-((3-fluorobenzyl)oxy)phenyl)-7-(4-((4-methyl-1,4-diazepan-1-yl)sulfonyl)phenyl)cinnolin-4-amine (NEU-1017, 68) for L. major and P. falciparum.

Global genetic analysis in mice unveils central role for cilia in congenital heart disease

Congenital heart disease (CHD) is the most prevalent birth defect, affecting nearly 1% of live births; the incidence of CHD is up to tenfold higher in human fetuses. A genetic contribution is strongly suggested by the association of CHD with chromosome abnormalities and high recurrence risk. Here we report findings from a recessive forward genetic screen in fetal mice, showing that cilia and cilia-transduced cell signalling have important roles in the pathogenesis of CHD. The cilium is an evolutionarily conserved organelle projecting from the cell surface with essential roles in diverse cellular processes. Using echocardiography, we ultrasound scanned 87,355 chemically mutagenized C57BL/6J fetal mice and recovered 218 CHD mouse models. Whole-exome sequencing identified 91 recessive CHD mutations in 61 genes. This included 34 cilia-related genes, 16 genes involved in cilia-transduced cell signalling, and 10 genes regulating vesicular trafficking, a pathway important for ciliogenesis and cell signalling. Surprisingly, many CHD genes encoded interacting proteins, suggesting that an interactome protein network may provide a larger genomic context for CHD pathogenesis. These findings provide novel insights into the potential Mendelian genetic contribution to CHD in the fetal population, a segment of the human population not well studied. We note that the pathways identified show overlap with CHD candidate genes recovered in CHD patients, suggesting that they may have relevance to the more complex genetics of CHD overall. These CHD mouse models and >8,000 incidental mutations have been sperm archived, creating a rich public resource for human disease modelling.

Interrogating congenital heart defects with noninvasive fetal echocardiography in a mouse forward genetic screen

BACKGROUND

Congenital heart disease (CHD) has a multifactorial pathogenesis, but a genetic contribution is indicated by heritability studies. To investigate the spectrum of CHD with a genetic pathogenesis, we conducted a forward genetic screen in inbred mice using fetal echocardiography to recover mutants with CHD. Mice are ideally suited for these studies given that they have the same four-chamber cardiac anatomy that is the substrate for CHD.

METHODS AND RESULTS

Ethylnitrosourea mutagenized mice were ultrasound-interrogated by fetal echocardiography using a clinical ultrasound system, and fetuses suspected to have cardiac abnormalities were further interrogated with an ultrahigh-frequency ultrasound biomicroscopy. Scanning of 46 270 fetuses revealed 1722 with cardiac anomalies, with 27.9% dying prenatally. Most of the structural heart defects can be diagnosed using ultrasound biomicroscopy but not with the clinical ultrasound system. Confirmation with analysis by necropsy and histopathology showed excellent diagnostic capability of ultrasound biomicroscopy for most CHDs. Ventricular septal defect was the most common CHD observed, whereas outflow tract and atrioventricular septal defects were the most prevalent complex CHD. Cardiac/visceral organ situs defects were observed at surprisingly high incidence. The rarest CHD found was hypoplastic left heart syndrome, a phenotype never seen in mice previously.

CONCLUSIONS

We developed a high-throughput, 2-tier ultrasound phenotyping strategy for efficient recovery of even rare CHD phenotypes, including the first mouse models of hypoplastic left heart syndrome. Our findings support a genetic pathogenesis for a wide spectrum of CHDs and suggest that the disruption of left-right patterning may play an important role in CHD.

Antitrypanosomal lead discovery: identification of a ligand-efficient inhibitor of Trypanosoma cruzi CYP51 and parasite growth

Chagas disease is caused by the intracellular protozoan parasite Trypanosomal cruzi , and current drugs are lacking in terms of desired safety and efficacy profiles. Following on a recently reported high-throughput screening campaign, we have explored initial structure-activity relationships around a class of imidazole-based compounds. This profiling has uncovered compounds 4c (NEU321) and 4j (NEU704), which are potent against in vitro cultures of T. cruzi and are greater than 160-fold selective over host cells. We report in vitro drug metabolism and properties profiling of 4c and show that this chemotype inhibits the T. cruzi CYP51 enzyme, an observation confirmed by X-ray crystallographic analysis. We compare the binding orientation of 4c to that of other, previously reported inhibitors. We show that 4c displays a significantly better ligand efficiency and a shorter synthetic route over previously disclosed CYP51 inhibitors, and should therefore be considered a promising lead compound for further optimization.

The anatomy of a novel malformation of the cardinal vein system

Anomalies of the cardinal vein system (CVS) are uncommon but if unidentified can lead to life-threatening complications. We report a case with a novel malformation of the CVS. Autopsy with in situ dissection of heart and large vessels in a 25-day-old infant was performed. The infant was diagnosed with congenital heart disease, and systemic venous malformations were suspected by imaging. Correlation between premortem imaging and postmortem anatomy was performed. The superior and inferior left venous systems developed abnormally. A persistent left superior vena cava (PLSVC) drained into the right atrium via the coronary sinus. A persistent left inferior vena cava (PLIVC) continued with the hemiazygos vein (HV), which drained into the PLSVC. The innominate vein was absent. The left renal vein was connected to the HV. Two common iliac veins were identified. The left drained into the PLIVC and the right into the right inferior vena cava (IVC). Perinatal echocardiography identified only the dilated HV draining to an LSVC and a small IVC. Congenital heart disease included hypoplastic left ventricle with hypoplastic aortic arch and subaortic stenosis, which were diagnosed by fetal ultrasound. Remodeling of components of CVS takes place during development, and unknown mechanisms guide this process. Defects of this process can lead to variable malformations, as demonstrated by this case. To our knowledge, the combination of complex malformations of both superior and IVC systems that extends to the common iliac veins has not been reported. We recommend identifying vascular anomalies in situ during autopsy before anatomic relationships are altered.

Late incompetence of the left atrioventricular valve after repair of atrioventricular septal defects: The morphologic perspective

OBJECTIVE

The mortality following repair of atrioventricular septal defects has fallen dramatically in the last 4 decades, but reoperation for late regurgitation across the left atrioventricular valve has remained disconcertingly stagnant. Seeking potential structural causes, we compared the morphology of the surgically created septal leaflet of the left valve following repair of atrioventricular septal defects to the aortic leaflet of the normal mitral valve.

METHODS

We compared the mitral valves of 92 normal hearts to the left ventricular components of the bridging leaflets of hearts with atrioventricular septal defect with common atrioventricular junction, determining the shape of the leaflets and the arrangement of the subvalvar apparatus.

RESULTS

The aortic leaflet of the mitral valve is triangular compared with its rectangular septal counterpart after repair of atrioventricular septal defect. The cordal arrangement in the mitral valve is well organized, compared with the deficient cordal arrangement of the abnormal valve. A greater proportion of cords in the mitral valve divide to 3 generations (55.5% compared with 8.7%; P < .001), and a higher percentage of cords remain undivided in atrioventricular septal defects (60.8% compared with 25%; P < .001).

CONCLUSIONS

Not only is the annular component in the left atrioventricular valve abnormal, but the subvalvar apparatus is characterized by deficiency and disarray. Furthermore, the axis of cordal insertion may potentiate to separation over the long term of the leaflets joined surgically. Valvar repair in this setting will never restore the arrangement of the normal mitral valve.

Abdominal obesity is associated with insulin resistance

BACKGROUND

Recent evidence suggests that insulin resistance and hyperinsulinemia may account for many of the medical complications of obesity. This study was performed to determine whether a predominance of body fat in the abdominal region is associated with insulin resistance and hyperinsulinemia.

METHODS

Two groups of nine obese women were matched for age and total obesity but differed significantly in the pattern of fat distribution as defined by the waist-to-hip circumference ratio (WHR). The high-WHR group had a WHR of 0.87 (+/- 0.01), and the low-WHR group had WHR of 0.77 (+/- 0.02) (P < .05).

RESULTS

Plasma levels of glucose, free fatty acids, and insulin, measured hourly for eight hours while the subjects consumed a diet of regular food, were higher in the high-WHR group.

CONCLUSION

The high-WHR group (abdominal obesity) was more resistant to the action of insulin. These results suggest that measurement of the WHR could help define the degree of medical risk for a given obese patient seeking treatment.

A randomized double-blind clinical trial of fluoxetine in obese diabetics

Fluoxetine is an inhibitor of serotonin re-uptake which has been found to produce weight loss in humans and animals. To test the effects of this drug in obese diabetic subjects, 48 male and female, obese type II non-insulin dependent (NIDDM) diabetics who were being treated with insulin were randomized to receive either fluoxetine 60 mg or a placebo once daily in a randomized double-blind fashion for 24 weeks. A four week single-blind placebo lead-in period preceded and a six week single-blind placebo period followed the double-blind treatment period. Subjects performed daily home glucose monitoring and were given instruction in a 1200kcal American Diabetic Association (ADA) diet. Subjects treated with fluoxetine achieved a maximum 8 kg greater weight loss on average than the placebo-treated subjects. At the end of active treatment, fluoxetine-treated subjects had significantly lower glycohaemoglobin levels than the placebo-treated group (9.72 vs. 10.76%, P < 0.05). In addition, fluoxetine-treated subjects showed a greater decrease in total daily insulin dose than placebo-treated subjects (44.5 vs. 20.1% decrease at the end of active treatment, P < 0.05). These results suggest that fluoxetine may be of benefit in the treatment of obese patients with type II non-insulin dependent diabetes mellitus.

Fluoxetine treatment of the obese diabetic

Fluoxetine, an inhibitor of serotonin re-uptake, has been shown to cause weight loss in humans and animals. In order to determine the effects in diabetic subjects, 48 male and female, obese, type 2 non-insulin dependent diabetics being treated with insulin were randomized to receive fluoxetine 60 mg or placebo once daily in double blind fashion for 24 weeks. In all subjects, this treatment was preceded by four weeks and followed by six weeks of single blind placebo washout treatment. Subjects performed daily home glucose monitoring and were given instruction in a 1200 kcal American Diabetes Association diet. Fluoxetine treated subjects who completed the trial (n = 16) lost more weight than placebo treated subjects (n = 20) (9.3 +/- 2.4 vs. 1.9 +/- 2.9 kg +/- s.e.m, P less than 0.05). Subjects in the fluoxetine group also showed a greater percentage decrease in insulin dose than those in the placebo group (46.9 +/- 7.6% vs. 19.3 +/- 7.6%, P less than 0.01). During active treatment, the change in serum glucose levels did not differ between the two groups, while glycohemoglobin fell more in fluoxetine treated subjects than in placebo treated subjects at two of four follow-up visits. These results suggest that fluoxetine may be of benefit in the treatment of obese patients with type 2 non-insulin dependent diabetes mellitus.

Magnetic-resonance imaging used for determining fat distribution in obesity and diabetes

Computed-tomography scanning and magnetic-resonance imaging (MRI) have been used to quantify intraabdominal and subcutaneous fat depots. In this study MRI was used to define fat-distribution patterns in 24 obese females with non-insulin-dependent diabetes (NIDDM) and 12 females with simple obesity. Subjects had anthropometric measurements and single-slice abdominal scans performed at the umbilicus. In addition, in 10 of the nondiabetic females, measurements were repeated after 10 wk of a very-low-calorie diet. Nondiabetic females had significantly less intraabdominal fat (P less than 0.01) than did the diabetics but had equivalent subcutaneous fat. There was no significant relationship between waist-to-hip ratio and intraabdominal fat, subcutaneous fat, or their ratio. After a weight loss of 10.6 +/- 3.8 kg there were significant decreases in both intraabdominal and subcutaneous fat (P less than 0.01). Weight loss is associated with decreases in fat in both depots.

Acetylcholinesterase-stained suction rectal biopsies in the diagnosis of Hirschsprung's disease

Conflicting reports in the literature regarding the sensitivity and specificity of the acetylcholinesterase (AChE) stain in establishing or excluding the diagnosis of Hirschsprung's disease (HD) prompted this review of 497 rectal biopsies performed on 455 children. Using hematoxylin and eosin (H&E) to stain formalin-fixed, paraffin-embedded tissue sections is our preferred method of identifying ganglion cells. In this series, however, there were eight children with HD, and nine without HD in whom the AChE-stained portion of the sample provided invaluable diagnostic information not obtained from the concomitant, formalin-fixed, H&E-stained portion of the sample. The AChE stain also provided at least suggestive evidence of HD in some of the anal or anorectal biopsy specimens.

The determination of atrial arrangement by examination of appendage morphology in 1842 heart specimens

The morphology of the atrial appendages was examined in 1842 specimen hearts from patients with congenital lesions. The external and internal features that permitted the identification of the right and left appendages were studied in detail in one tenth of the hearts. These results were compared with a similar analysis of 25 normal hearts. This study showed that criteria for identification of right and left appendages were reliable. Application of these criteria to the overall collection identified the usual arrangement in 1776 (97%) hearts, a mirror image arrangement in eight (0.4%); left atrial isomerism in 22 (1.2%); and right atrial isomerism in 36 (1.9%). Fourteen (0.81%) had juxtaposed atrial appendages (13 with usual arrangement and one with left isomerism). This did not interfere with identification of the left and right atria on the basis of appendage morphology. In only two cases did the determination by atrial morphology produce a result that was inconsistent with the arrangement of the other thoracoabdominal organs. Further examination of the atria in these showed a mistake had been made in the initial assessment. The atrial arrangement can be accurately determined by the morphology of the atrial appendages.

Identification and analysis of left atrial isomerism

The veno-atrial connections, atrial morphology, atrioventricular (AV) junction, ventricular mass, ventriculoarterial (VA) connection and great arteries in 22 autopsied hearts, diagnosed as having bilateral left-sidedness because of the morphology of the atrial appendages, were studied. The findings were correlated with the arrangement of the thoracic-abdominal organs. A solitary spleen was found in 3 and double spleens in 2 hearts (the remaining 17 hearts had multiple spleens) but left bronchial isomerism existed in all hearts in which bronchial arrangement could be determined. The heart was in the left chest in 14 cases, in the right chest in 5 and midline in 3. The apex pointed to the left in 18 hearts while in 4 hearts it pointed to the right. Fifteen hearts had a biventricular and ambiguous AV connection, 3 hearts had an absent left AV connection and 4 had double-inlet connection via a common valve (to the left ventricle in 3 and the right ventricle in 1). The VA connection was concordant in 14 hearts, discordant in 1, double outlet from the right ventricle in 4, double outlet from a solitary indeterminate ventricle in 1 and single outlet from the right ventricle through a pulmonary trunk with aortic atresia in 2 hearts. Superior caval veins were present bilaterally in 13 hearts. There was interruption of the infrahepatic inferior caval vein with azygos or hemiazygos continuation in 19 hearts while in 3 hearts the inferior caval vein continued upwards to drain into the right-sided morphologically left atrium.(ABSTRACT TRUNCATED AT 250 WORDS)

The pattern of cardiovascular malformation in the CHARGE association

Congenital heart disease occurred in 64% of patients with the CHARGE (coloboma, heart disease, choanal atresia, retardation of postnatal growth and mental development, genitalia hypoplasia, and ear anomalies) association (55% of 67 previously described patients and 100% of 16 new patients). Of those with congenital heart disease, 42% had conotruncal anomalies (tetralogy of Fallot, double-outlet right ventricle, truncus arteriosus), and 36% had aortic arch anomalies (vascular ring, aberrant subclavian artery, interrupted aortic arch). This striking pattern of cardiovascular malformations is similar to that found in the DiGeorge sequence.