Further description of two individuals with de novo p.(Glu127Lys) missense variant in the ASCL1 gene

Achaete-Scute Family basic-helix-loop-helix (bHLH) Transcription Factor 1 (ASCL1) is a proneural transcription factor involved in neuron development in the central and peripheral nervous system. While initially suspected to contribute to congenital central hypoventilation syndrome-1 (CCHS) with or without Hirschsprung disease (HSCR) in three individuals, its implication was ruled out by the presence, in one of the individuals, of a Paired-like homeobox 2B (PHOX2B) heterozygous polyalanine expansion variant, known to cause CCHS. We report two additional unrelated individuals sharing the same sporadic ASCL1 p.(Glu127Lys) missense variant in the bHLH domain and a common phenotype with short-segment HSCR, signs of dysautonomia, and developmental delay. One has also mild CCHS without polyalanine expansion in PHOX2B, compatible with the diagnosis of Haddad syndrome. Furthermore, missense variants with homologous position in the same bHLH domain in other genes are known to cause human diseases. The description of additional individuals carrying the same variant and similar phenotype, as well as targeted functional studies, would be interesting to further evaluate the role of ASCL1 in neurocristopathies.

The Streptococcus agalactiae Exonuclease ExoVII Is Required for Resistance to Exogenous DNA-Damaging Agents

Streptococcus agalactiae is a human pathogen responsible for severe invasive infections in newborns. In this bacterium, XseB, a part of the ExoVII exonuclease, was shown to be specifically more abundant in the hypervirulent ST-17 strains. In Escherichia coli, ExoVII is associated either with mismatch repair or with recombinational DNA repair and is redundant with other exonucleases. In this study, the biological role of S. agalactiae ExoVII was examined. The ΔexoVII mutant strain was subjected to different DNA-damaging agents, as well as a large set of mutants impaired either in the mismatch repair pathway or in processes of recombinational DNA repair. Our results clarified the role of this protein in Gram-positive bacteria as we showed that ExoVII is not significantly involved in mismatch repair but is involved in bacterial recovery after exposure to exogenous DNA-damaging agents such as ciprofloxacin, UV irradiation, or hydrogen peroxide. We found that ExoVII is more particularly important for resistance to ciprofloxacin, likely as part of the RecF DNA repair pathway. Depending on the tested agent, ExoVII appeared to be fully redundant or nonredundant with another exonuclease, RecJ. The importance of each exonuclease, ExoVII or RecJ, in the process of DNA repair is thus dependent on the considered DNA lesion. IMPORTANCE This study examined the role of the ExoVII exonuclease of Streptococcus agalactiae within the different DNA repair processes. Our results concluded that ExoVII is involved in bacterial recovery after exposure to different exogenous DNA-damaging agents but not in the mismatch repair pathway. We found that ExoVII is particularly important for resistance to ciprofloxacin, likely as part of the RecF DNA repair pathway.

SRSF1 haploinsufficiency is responsible for a syndromic developmental disorder associated with intellectual disability

SRSF1 (also known as ASF/SF2) is a non-small nuclear ribonucleoprotein (non-snRNP) that belongs to the arginine/serine (R/S) domain family. It recognizes and binds to mRNA, regulating both constitutive and alternative splicing. The complete loss of this proto-oncogene in mice is embryonically lethal. Through international data sharing, we identified 17 individuals (10 females and 7 males) with a neurodevelopmental disorder (NDD) with heterozygous germline SRSF1 variants, mostly de novo, including three frameshift variants, three nonsense variants, seven missense variants, and two microdeletions within region 17q22 encompassing SRSF1. Only in one family, the de novo origin could not be established. All individuals featured a recurrent phenotype including developmental delay and intellectual disability (DD/ID), hypotonia, neurobehavioral problems, with variable skeletal (66.7%) and cardiac (46%) anomalies. To investigate the functional consequences of SRSF1 variants, we performed in silico structural modeling, developed an in vivo splicing assay in Drosophila, and carried out episignature analysis in blood-derived DNA from affected individuals. We found that all loss-of-function and 5 out of 7 missense variants were pathogenic, leading to a loss of SRSF1 splicing activity in Drosophila, correlating with a detectable and specific DNA methylation episignature. In addition, our orthogonal in silico, in vivo, and epigenetics analyses enabled the separation of clearly pathogenic missense variants from those with uncertain significance. Overall, these results indicated that haploinsufficiency of SRSF1 is responsible for a syndromic NDD with ID due to a partial loss of SRSF1-mediated splicing activity.

Bi-allelic loss-of-function variants in TMEM147 cause moderate to profound intellectual disability with facial dysmorphism and pseudo-Pelger-Huët anomaly

The transmembrane protein TMEM147 has a dual function: first at the nuclear envelope, where it anchors lamin B receptor (LBR) to the inner membrane, and second at the endoplasmic reticulum (ER), where it facilitates the translation of nascent polypeptides within the ribosome-bound TMCO1 translocon complex. Through international data sharing, we identified 23 individuals from 15 unrelated families with bi-allelic TMEM147 loss-of-function variants, including splice-site, nonsense, frameshift, and missense variants. These affected children displayed congruent clinical features including coarse facies, developmental delay, intellectual disability, and behavioral problems. In silico structural analyses predicted disruptive consequences of the identified amino acid substitutions on translocon complex assembly and/or function, and in vitro analyses documented accelerated protein degradation via the autophagy-lysosomal-mediated pathway. Furthermore, TMEM147-deficient cells showed CKAP4 (CLIMP-63) and RTN4 (NOGO) upregulation with a concomitant reorientation of the ER, which was also witnessed in primary fibroblast cell culture. LBR mislocalization and nuclear segmentation was observed in primary fibroblast cells. Abnormal nuclear segmentation and chromatin compaction were also observed in approximately 20% of neutrophils, indicating the presence of a pseudo-Pelger-Huët anomaly. Finally, co-expression analysis revealed significant correlation with neurodevelopmental genes in the brain, further supporting a role of TMEM147 in neurodevelopment. Our findings provide clinical, genetic, and functional evidence that bi-allelic loss-of-function variants in TMEM147 cause syndromic intellectual disability due to ER-translocon and nuclear organization dysfunction.

Dual role of histone variant H3.3B in spermatogenesis: positive regulation of piRNA transcription and implication in X-chromosome inactivation

The histone variant H3.3 is encoded by two distinct genes, H3f3a and H3f3b, exhibiting identical amino-acid sequence. H3.3 is required for spermatogenesis, but the molecular mechanism of its spermatogenic function remains obscure. Here, we have studied the role of each one of H3.3A and H3.3B proteins in spermatogenesis. We have generated transgenic conditional knock-out/knock-in (cKO/KI) epitope-tagged FLAG-FLAG-HA-H3.3B (H3.3B^HA) and FLAG-FLAG-HA-H3.3A (H3.3A^HA) mouse lines. We show that H3.3B, but not H3.3A, is required for spermatogenesis and male fertility. Analysis of the molecular mechanism unveils that the absence of H3.3B led to alterations in the meiotic/post-meiotic transition. Genome-wide RNA-seq reveals that the depletion of H3.3B in meiotic cells is associated with increased expression of the whole sex X and Y chromosomes as well as of both RLTR10B and RLTR10B2 retrotransposons. In contrast, the absence of H3.3B resulted in down-regulation of the expression of piRNA clusters. ChIP-seq experiments uncover that RLTR10B and RLTR10B2 retrotransposons, the whole sex chromosomes and the piRNA clusters are markedly enriched of H3.3. Taken together, our data dissect the molecular mechanism of H3.3B functions during spermatogenesis and demonstrate that H3.3B, depending on its chromatin localization, is involved in either up-regulation or down-regulation of expression of defined large chromatin regions.

CETP activity is not associated with carotid intima-media thickness in patients with poorly controlled type 2 diabetes

AIM

The impact of cholesteryl ester transfer protein (CETP) on atherosclerotic development in humans remains unclear. Plasma cholesteryl ester transfer was shown to be associated with carotid intima-media thickness in type 2 diabetic (T2D) patients with adequate metabolic control. Since glycation of CETP may influence cholesteryl ester transfer processes, it is important to determine if plasma cholesteryl ester transfer is still a determinant of carotid intima-media thickness (IMT) in patients with poorly controlled diabetes. The aim of the present study was to determine whether CETP activity influences carotid IMT in T2D patients with poor metabolic control.

METHODS

In 110 individuals with T2D, we measured CETP mass concentration with ELISA, CETP activity with a radioactivity method and carotid intima-media thickness with high-resolution real-time B-mode ultrasonography.

RESULTS

The mean HbA1C was 8.8 ± 1.7%. Carotid IMT did not correlate with CETP activity in the total population. In T2D patients with HbA1C < 8% (n = 33), mean HbA1C was 6.9% and the correlation between carotid IMT and CETP activity was not significant (p = 0.09). In a multivariable analysis that included the total population, carotid intima-media thickness was positively associated with diabetes duration (p = 0.02) but not with CETP activity or HbA1C.

CONCLUSIONS

We observed no correlation between carotid intima-media thickness, a marker of early atherosclerosis, and CETP activity in T2D patients with poor metabolic control. Disease duration, which reflects accumulated metabolic abnormalities, may have blunted the potential effect of CETP on atherosclerosis. Metabolic control appears essential to determine the pro- or anti-atherogenic influence of CETP in patients with T2D.

Semi-automated fact-checking of nucleotide sequence reagents in biomedical research publications: The Seek & Blastn tool

Nucleotide sequence reagents are verifiable experimental reagents in biomedical publications, because their sequence identities can be independently verified and compared with associated text descriptors. We have previously reported that incorrectly identified nucleotide sequence reagents are characteristic of highly similar human gene knockdown studies, some of which have been retracted from the literature on account of possible research fraud. Because of the throughput limitations of manual verification of nucleotide sequences, we developed a semi-automated fact checking tool, Seek & Blastn, to verify the targeting or non-targeting status of published nucleotide sequence reagents. From previously described and unknown corpora of 48 and 155 publications, respectively, Seek & Blastn correctly extracted 304/342 (88.9%) and 1066/1522 (70.0%) nucleotide sequences and a predicted targeting/ non-targeting status. Seek & Blastn correctly predicted the targeting/ non-targeting status of 293/304 (96.4%) and 988/1066 (92.7%) of the correctly extracted nucleotide sequences. A total of 38/39 (97.4%) or 31/79 (39.2%) Seek & Blastn predictions of incorrect nucleotide sequence reagent use were correct in the two literature corpora. Combined Seek & Blastn and manual analyses identified a list of 91 misidentified nucleotide sequence reagents, which could be built upon through future studies. In summary, incorrect nucleotide sequence reagents represent an under-recognized source of error within the biomedical literature, and fact checking tools such as Seek & Blastn may help to identify papers and manuscripts affected by these errors.

β1 integrins mediate the BMP2 dependent transcriptional control of osteoblast differentiation and osteogenesis

Osteoblast differentiation is a highly regulated process that requires coordinated information from both soluble factors and the extracellular matrix. Among these extracellular stimuli, chemical and physical properties of the matrix are sensed through cell surface receptors such as integrins and transmitted into the nucleus to drive specific gene expression. Here, we showed that the conditional deletion of β1 integrins in the osteo-precursor population severely impacts bone formation and homeostasis both in vivo and in vitro. Mutant mice displayed a severe bone deficit characterized by bone fragility and reduced bone mass. We showed that β1 integrins are required for proper BMP2 dependent signaling at the pre-osteoblastic stage, by positively modulating Smad1/5-dependent transcriptional activity at the nuclear level. The lack of β1 integrins results in a transcription modulation that relies on a cooperative defect with other transcription factors rather than a plain blunted BMP2 response. Our results point to a nuclear modulation of Smad1/5 transcriptional activity by β1 integrins, allowing a tight control of osteoblast differentiation.

Guiding the non-bariatric surgeon through complications of bariatric surgery

Complications in bariatric surgery are varied; they are severe at times but infrequent. They may be surgical or non-surgical, and may occur early or late. The goal of this systematic review is to inform and help the attending physician, the emergency physician and the non-bariatric surgeon who may be called upon to manage surgical complications that arise after adjustable gastric band (AGB), sleeve gastrectomy (SG), or gastric bypass (GBP). Data from evidence-based medicine were extracted from the literature by a review of the Medline database and also of the most recent recommendations of the learned societies implicated. The main complications were classified for each intervention, and a distinction was made between early and late complications. Early complications after AGB include prosthetic slippage or perforation; SG can be complicated early by staple line leak or fistula, and BPG by fistula, stenosis and postoperative hemorrhage. Delayed complications of AGB include intragastric migration of the prosthesis, late prosthetic slippage and infection, while SG can be complicated by gastro-esophageal reflux, and BPG by anastomotic ulcer and internal hernia. The analysis of available data allowed us to develop decisional algorithms for the management of each of these complications.

Plasma apolipoprotein C1 concentration is associated with plasma triglyceride concentration, but not visceral fat, in patients with type 2 diabetes

INTRODUCTION

Apolipoprotein C1 (apoC1) is likely to play an important role in triglyceride (TG) metabolism. Mice overexpressing human apoC1 present decreased adipose tissue stores. This study aimed to determine whether apoC1 concentration influences fat mass and distribution and liver fat content (LFC) in patients with type 2 diabetes (T2D).

METHODS

ApoC1 concentrations were measured by ELISA in 113 T2D patients and 56 normolipidaemic-normoglycaemic subjects. Visceral and subcutaneous fat areas were determined by single-slice axial T1-weighted magnetic resonance imaging (MRI), while LFC was measured by hydrogen-1 ((1)H) MR spectroscopy.

RESULTS

ApoC1 concentrations were higher in T2D patients than in normolipidaemic-normoglycaemic subjects (P<0.0001), and did not correlate with visceral or subcutaneous fat areas, but significantly correlated with TG (P<0.0001) and LFC (P=0.02) in T2D patients. However, the correlation between apoC1 and LFC was lost after adjusting for TG. ApoC1 concentration was also significantly higher in T2D patients with TG<1.5mmol/L than in control subjects (P<0.0001), although both groups had similar TG levels. On multivariate analysis performed in T2D patients with TG<1.5mmol/L and control subjects, apoC1 concentration was independently and positively associated with type 2 diabetes (P<0.0001) and TG levels (P=0.03).

CONCLUSION

This study reports, for the first time, that apoC1 is increased in T2D patients and is significantly correlated with TG, whereas no association was found between apoC1 and adipose tissue. This indicates that, in T2D, apoC1 may play a role in TG metabolism, but is unlikely to modulate fat mass and distribution. This increased apoC1 concentration in T2D patients is not only explained by the increased TG level in T2D patients.

Stenosis without stricture after sleeve gastrectomy

Sleeve gastrectomy (SG) is an increasingly popular restrictive bariatric procedure as attested by the 5,302 procedures performed in 2009, increasing worldwide to 13,557 in 2011 and to 24,190 in 2013. Among the early complications, gastric stricture is well described with a prevalence between 0.7 and 4.0% (Dhahri et al., 2010). The patient reported here had functional stenosis without any underlying anatomic stricture. This complication is rare and is the consequence of spiral stapling resulting in a gastric tube that is twisted from the start (Iannelli et al., 2014). Twisted sleeve gastrectomy resulting from spiral stapling exposes the patient to the risk of recurrent dysphagia, which has the appearance of stenosis on upper GI series but not on fibroscopy. Conversion to RY-GBP is one solution. At six months follow-up after conversion, our patient is symptom-free, with quality of life was rated excellent (a score greater than 9 on the BAROS questionnaire).

The incorporation of the novel histone variant H2AL2 confers unusual structural and functional properties of the nucleosome

In this work we have studied the properties of the novel mouse histone variant H2AL2. H2AL2 was used to reconstitute nucleosomes and the structural and functional properties of these particles were studied by a combination of biochemical approaches, atomic force microscopy (AFM) and electron cryo-microscopy. DNase I and hydroxyl radical footprinting as well as micrococcal and exonuclease III digestion demonstrated an altered structure of the H2AL2 nucleosomes all over the nucleosomal DNA length. Restriction nuclease accessibility experiments revealed that the interactions of the H2AL2 histone octamer with the ends of the nucleosomal DNA are highly perturbed. AFM imaging showed that the H2AL2 histone octamer was complexed with only ∼130 bp of DNA. H2AL2 reconstituted trinucleosomes exhibited a type of a ‘beads on a string’ structure, which was quite different from the equilateral triangle 3D organization of conventional H2A trinucleosomes. The presence of H2AL2 affected both the RSC and SWI/SNF remodeling and mobilization of the variant particles. These unusual properties of the H2AL2 nucleosomes suggest a specific role of H2AL2 during mouse spermiogenesis.

Hemodialysis reduces plasma apolipoprotein C-I concentration making VLDL a better substrate for lipoprotein lipase

Apolipoprotein Cs (apoC-1, apoC-II, and apoC-III) are lipoprotein components that have regulatory effects on enzymes involved in lipoprotein metabolism. Owing to their low molecular weights, apoCs can adsorb onto and/or pass through dialysis membranes. Our study determines the consequence of hemodialysis (HD) on plasma concentrations of apoCs and on the activities of enzymes modulated by apoCs. Plasma samples were collected from 28 patients with chronic renal failure before and after HD. Plasma apoC-II levels were unchanged, whereas apoC-III levels were slightly decreased in post-dialysis plasmas. The apoC-I content was markedly reduced during HD. This was due to a significant decrease in the apoC-I content of very low-density lipoprotein (VLDL), whereas the apoC-I content of high-density lipoprotein (HDL) was unchanged. Although HDL bound apoC-I is thought to inhibit cholesterol ester transfer protein, no change in the ability of pre- and post-dialysis VLDL to interact with the transfer protein were observed. Complementary experiments confirmed that VLDL-bound apoC-I has no transfer protein inhibitory potential. In contrast, an increase in the ability of post-dialysis apoC-I-poor VLDL to act as substrate for lipoprotein lipase (LPL) was found compared to pre-dialysis VLDL. Our study shows that apoC-I losses during HD might be beneficial by improving the ability of VLDL to be a substrate for LPL thus improving plasma triglyceride metabolism.

Dissection of the unusual structural and functional properties of the variant H2A.Bbd nucleosome

The histone variant H2A.Bbd appeared to be associated with active chromatin, but how it functions is unknown. We have dissected the properties of nucleosome containing H2A.Bbd. Atomic force microscopy (AFM) and electron cryo-microscopy (cryo-EM) showed that the H2A.Bbd histone octamer organizes only approximately 130 bp of DNA, suggesting that 10 bp of each end of nucleosomal DNA are released from the octamer. In agreement with this, the entry/exit angle of the nucleosomal DNA ends formed an angle close to 180 degrees and the physico-chemical analysis pointed to a lower stability of the variant particle. Reconstitution of nucleosomes with swapped-tail mutants demonstrated that the N-terminus of H2A.Bbd has no impact on the nucleosome properties. AFM, cryo-EM and chromatin remodeling experiments showed that the overall structure and stability of the particle, but not its property to interfere with the SWI/SNF induced remodeling, were determined to a considerable extent by the H2A.Bbd docking domain. These data show that the whole H2A.Bbd histone fold domain is responsible for the unusual properties of the H2A.Bbd nucleosome.

The NH2 tail of the novel histone variant H2BFWT exhibits properties distinct from conventional H2B with respect to the assembly of mitotic chromosomes

We have studied the functional and structural properties of nucleosomes reconstituted with H2BFWT, a recently identified putative histone variant of the H2B family with totally unknown function. We show that H2BFWT can replace the conventional histone H2B in the nucleosome. The presence of H2BFWT did not affect the overall structure of the nucleosome, and the H2BFWT nucleosomes exhibited the same stability as conventional nucleosomes. SWI/SNF was able to efficiently remodel and mobilize the H2BFWT nucleosomes. Importantly, H2BFWT, in contrast to conventional H2B, was unable to recruit chromosome condensation factors and to participate in the assembly of mitotic chromosomes. This was determined by the highly divergent (compared to conventional H2B) NH2 tail of H2BFWT. These data, in combination with the observations that H2BFWT was found by others in the sperm nuclei and appeared to be associated with the telomeric chromatin, suggest that H2BFWT could act as a specific epigenetic marker.

Triple helix formation with Drosophila satellite repeats. Unexpected stabilization by copper ions

The Drosophila melanogaster (AAGAGAG)(n) satellite repeat represents up to 1.5% of the entire fly genome and may adopt non-B DNA structures such as pyrimidine triple helices. UV melting and electrophoretic mobility shift assay experiments were used to monitor the stability of intermolecular triple helices as a function of size, pH, and backbone or base modification. Three to four repeats of the heptanucleotide motif were sufficient to allow the formation of a stable complex, especially when modified TFOs were used. Unexpectedly, low concentrations (40-100 microM) of Cu(2+) were found to favor strongly pyrimidine triplex formation under near-physiological conditions. In contrast, a much higher magnesium concentration was required to stabilize these triplexes significantly, suggesting that copper may be an essential stabilizing factor for pyrimidine triplexes.

Histone variant H2ABbd confers lower stability to the nucleosome

The histone H2ABbd is a novel histone variant of H2A with a totally unknown function. We have investigated the behaviour of the H2ABbd nucleosomes. Nucleosomes were reconstituted with recombinant histone H2ABbd and changes in their conformations at different salt concentrations were studied by analytical centrifugation. The data are in agreement with H2ABbd being less tightly bound compared with conventional H2A in the nucleosome. In addition, stable cell lines expressing either green fluorescent protein (GFP)-H2A or GFP-H2ABbd were established and the mobility of both fusions was measured by fluorescence recovery after photobleaching. We show that GFP-H2ABbd exchanges much more rapidly than GFP-H2A within the nucleosome. The reported data are compatible with a lower stability of the variant H2ABbd nucleosome compared with the conventional H2A particle.

Fluorescence-based assessment of LRP activity: a comparative study

BACKGROUND

Broad resistance to anticancer drugs is a major cause of failure in cancer treatment. The Lung Resistance-related Protein (LRP) is a protein associated with drug resistance, which is involved in nucleo-cytoplasmic transport and is known to predict a poor response to chemotherapy in acute myeloid leukaemia. The only method allowing the detection of LRP activity is based on radio-labelled daunorubicin incorporation. Our goal was to develop a fluorescence-based assay to analyse LRP function.

MATERIALS AND METHODS

We used human colon carcinoma cell lines treated with sodium butyrate (NaB) in order to induce LRP expression. Daunorubicin efflux in isolated nuclei was measured by flow cytometry, the localization and quantification of Daunorubicin analysed by confocal laser scanning microscopy (CLSM) and the diffusion coefficient of this drug estimated by Fluorescence Correlation Spectrometry (FCS).

RESULTS

According to the method using [14C] Doxorubicin cells incubated with NaB displayed an efflux of Daunorubicin out of isolated nuclei demonstrated by flow cytometry or CLSM. The FCS method was able to evaluate kinetics of Daunorubicin molecules in nucleus and cytoplasm and showed a higher dispersion of Daunorubicin kinetics with cells previously NaB-treated. This argument is in favour of an increase of nucleo-cytoplasmic exchange.

CONCLUSION

Using CLSM we showed that LRP was able to modify anticancer drug repartition in the cells. LRP activity assessment needs either isolated nuclei if flow cytometry is employed, or FCS, and only a few cells may be analysed.

Human seminal plasma displays significant phospholipid transfer activity due to the presence of active phospholipid transfer protein

The lipid composition of germ cell membranes is considerably modified during spermatogenesis, sperm maturation and capacitation. Some of these modifications are caused by exchanges between soluble lipid donors or acceptors and cell membranes. The aim of this study was to assess whether significant lipid transfers between lipoprotein structures are detectable in human seminal plasma. Phospholipid and cholesteryl ester (CE) transfer activities were measured by specific fluorescence and isotopic assays. Seminal plasma samples did not display significant CE transfer. Substantial levels of phospholipid transfer activity were detected in all samples studied, levels were approximately 25% of the phospholipid transfer activity measured in human blood plasma. Concordantly, CE transfer protein was not detected in seminal plasma, while the presence of the phospholipid transfer protein (PLTP) was confirmed by Western blot analysis. Enzyme-linked immunosorbent assay indicated that seminal PLTP concentrations represented 25% of the concentration measured in blood plasma. Blockade of phosphatidylcholine and phosphatidyl-ethanolamine transfer by a 60 min, 56 degrees C heating step or with anti-PLTP antibody revealed that PLTP accounts for almost 80% of the phospholipid transfer activity present in seminal plasma. As shown by gel-permeation chromatography and Western blot analysis, seminal PLTP activity was partially associated with prostasomes. Significantly higher PLTP activity levels were measured in seminal plasma samples with low seminal vesicle secretions. The latter observation may reflect the sustained secretion of active PLTP that is diluted in a variable volume of PLTP-free seminal vesicle secretion. In conclusion, human seminal plasma displays significant phospholipid transfer activity due to the presence of active PLTP.

[Clonidine combined with flunitrazepam before carotid endarterectomy decreases cerebrovascular CO2 reactivity]

OBJECTIVE

Assess cerebrovascular CO2 reactivity changes using transcranial Doppler sonography (TCD) after oral premedication associating clonidine (2 micrograms.kg-1) and flunitrazepam (70 micrograms.kg-1) in patients scheduled for carotid stenosis surgery.

STUDY DESIGN

Prospective study, not randomized, the patient being his own "control".

PATIENTS AND METHODS

Thirteen patients undergoing carotid endarterectomy under cervical plexus block were included. The monitoring included: automated arterial pressure cuff, ECG, radial artery catheter, TCD with probe secured in temporal window. The study of the cerebrovascular CO2 reactivity was performed with TCD recording on the side of operation, on the day before, and on the day of carotid endarterectomy, 90 min after the premedication, immediately before surgery. To change PaCO2, four ventilatory states were successively performed: (1) normoventilation, (2) hyperventilation, (3) hypoventilation, (4) "breath-holding test". At each state, it was noted: HR, MAP, PaCO2, mean blood flow velocity in the middle cerebral artery (Vm-MCA), resistance index of Pourcelot (RI), cerebrovascular reactivity (slope Vm-MCA/PaCO2). The results (+/- SEM) were analyzed by Wilcoxon test or t test.

RESULTS

After premedication, cerebrovascular CO2 reactivity decreased (0.043 +/- 0.019 vs 0.034 +/- 0.013; p < 0.05) without modification of RI (0.578 +/- 0.291 vs 0.612 +/- 0.025; NS). No complication during carotid clamping was reported.

CONCLUSION

Inclusion of clonidine in premedication before carotid stenosis surgery must be questioned because a decrease of cerebrovascular CO2 reactivity could be deleterious in case of intraoperative stroke.

Human apolipoprotein C-I accounts for the ability of plasma high density lipoproteins to inhibit the cholesteryl ester transfer protein activity

The aim of the present study was to identify the protein that accounts for the cholesteryl ester transfer protein (CETP)-inhibitory activity that is specifically associated with human plasma high density lipoproteins (HDL). To this end, human HDL apolipoproteins were fractionated by preparative polyacrylamide gradient gel electrophoresis, and 30 distinct protein fractions with molecular masses ranging from 80 down to 2 kDa were tested for their ability to inhibit CETP activity. One single apolipoprotein fraction was able to completely inhibit CETP activity. The N-terminal sequence of the 6-kDa protein inhibitor matched the N-terminal sequence of human apoC-I, the inhibition was completely blocked by specific anti-apolipoprotein C-I antibodies, and mass spectrometry analysis confirmed the identity of the isolated inhibitor with full-length human apoC-I. Pure apoC-I was able to abolish CETP activity in a concentration-dependent manner and with a high efficiency (IC(50) = 100 nmol/liter). The inhibitory potency of total delipidated HDL apolipoproteins completely disappeared after a treatment with anti-apolipoprotein C-I antibodies, and the apoC-I deprivation of native plasma HDL by immunoaffinity chromatography produced a mean 43% rise in cholesteryl ester transfer rates. The main localization of apoC-I in HDL and not in low density lipoprotein in normolipidemic plasma provides further support for the specific property of HDL in inhibiting CETP activity.

Nucleolar KKE/D repeat proteins Nop56p and Nop58p interact with Nop1p and are required for ribosome biogenesis

Different point mutations in the nucleolar protein fibrillarin (Nop1p in Saccharomyces cerevisiae) can inhibit different steps in ribosome synthesis. A screen for mutations that are synthetically lethal (sl) with the nop1-5 allele, which inhibits pre-rRNA processing, identified NOP56. An independent sl mutation screen with nop1-3, which inhibits pre-rRNA methylation, identified a mutation in NOP58. Strikingly, Nop56p and Nop58p are highly homologous (45% identity). Both proteins were found to be essential and localized to the nucleolus. A temperature-sensitive lethal mutant allele, nop56-2, inhibited many steps in pre-rRNA processing, particularly on the pathway of 25S/5.8S rRNA synthesis, and led to defects in 60S subunit assembly. Epitope-tagged constructs show that both Nop56p and Nop58p are associated with Noplp in complexes, Nop56p and Nop1p exhibiting a stoichiometric association. These physical interactions presumably underlie the observed sl phenotypes. Well-conserved homologs are present in a range of organisms, including humans (52% identity between human hNop56p and yeast Nop56p), suggesting that these complexes have been conserved in evolution.

Normal ranges for immunochemiluminometric gonadotropin assays

OBJECTIVE

We sought to establish normative data for spontaneous and gonadotropin-releasing hormone (GnRH)-stimulated serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels measured by new immunochemiluminometric assays (ICMA) in children and adolescents.

METHODS

Random serum samples were obtained from 375 normal subjects (0.1 to 17.7 years, 230 female subjects). Intravenous GnRH stimulation tests were performed in 41 normal subjects (4.8 to 18 years, 20 female subjects). Normal ranges were calculated by age and Tanner stage. Immunochemiluminometric assays of LH and FSH concentrations were compared with levels obtained by a sensitive immunofluorometric assay and a less sensitive radioimmunoassay.

RESULTS

Random gonadotropin concentrations in normal children followed the pattern of transient elevation in infancy, low but measurable prepubertal levels, and markedly increased values at puberty. Spontaneous LH levels were higher in male infants but were not statistically different in boys and girls after infancy. Mean prepubertal LH was 0.04 +/- 0.04 IU/L (n = 66), rising 100-fold during puberty. Spontaneous FSH levels were much higher than LH values, were higher in female infants, and rose threefold at puberty. Peak GnRH-stimulated LH was identical in prepubertal boys and girls (1.8 +/- 1.3 IU/L, n = 17) and increased 20-fold at puberty. Mean peak GnRH-stimulated FSH was highest in prepubertal female subjects. Luteinizing hormone values measured by ICMA and immunofluorometric assay were highly correlated, but radioimmunoassay levels diverged markedly from ICMA levels at lower concentrations. Because absolute levels were higher, FSH values correlated adequately in the three assays throughout the normal physiologic range.

CONCLUSIONS

Measurement of LH by ICMA is much more sensitive than older assay methods. Spontaneous LH can be accurately measured by ICMA to the very low levels present in normal prepubertal children, providing a potentially important biochemical discriminator of pubertal status. An ICMA GnRH-stimulated LH level greater than 5 IU/L is suggestive of maturing gonadotropin secretion. The ICMA LH assays provide significant enhancement in sensitivity; these assays should be used when levels may be low, and by their accuracy may reduce the time and expense of testing procedures.

Dihydrotestosterone regulation of semen in male pseudohermaphrodites with 5 alpha-reductase-2 deficiency

Semen analyses were performed in nine male pseudohermaphrodites with inherited 5 alpha-reductase-2 deficiency and decreased dihydrotestosterone (DHT) production. The semen samples were characterized by extremely low volume (range, < 0.05 to 1.0 mL), increased viscosity, and poor liquefaction. Surgical correction of pseudovaginal perineoscrotal hypospadias in four subjects did not result in an increase in semen volume or a change in viscosity. Inexplicably, semen liquefaction reverted to normal. Affected males have rudimentary prostates and small seminal vesicles. Six subjects had bilaterally descended testes, one subject had bilaterally retractile testes, and two subjects had unilaterally undescended testes. Semen from one subject with bilaterally descended testes had a normal sperm concentration, normal total sperm count, and normal motility and morphology. Semen from another subject who was oligospermic at baseline demonstrated a normal sperm concentration after hypospadias repair, with a low total sperm count. The other subjects studied were oligospermic or azospermic. In summary, DHt appears to regulate semen volume and viscosity through its action on the development and function of the prostate and seminal vesicles. The finding of normal sperm concentrations in two subjects with 5 alpha-reductase-2 deficiency suggests that DHT does not play a major role in spermatogenesis. However, the possibility that low levels of DHT might be sufficient for normal spermatogenesis must also be considered.

Luteinizing hormone pulsatility in subjects with 5-alpha-reductase deficiency and decreased dihydrotestosterone production

The pattern of LH pulsatility in male pseudohermaphrodites with inherited 5 alpha-reductase-2 deficiency (5 alpha RD) and decreased levels of plasma dihydrotestosterone was compared to that in normal males. Analysis of 10-min plasma LH sampling during either a 10- or 24-h period demonstrated that the subjects with 5 alpha RD had 1) a mean plasma LH level, mean LH pulse amplitude, and mean plasma LH nadir that were approximately twice normal; and 2) a mean LH pulse frequency similar to that in normal males, whether described as pulses per h or pulses per study period. An increased plasma LH response to GnRH administration was also noted. The findings suggest that a deficiency of DHT results in decreased negative feedback at the level of the hypothalamus and/or pituitary, resulting in an increase in mean plasma LH, LH pulse amplitude, and LH responsiveness to GnRH. In response to increased LH, mean plasma testosterone (T), free T, and plasma estradiol (E2) are increased. The pulse amplitude is increased despite elevated plasma T and E2 levels; this underscores the importance of DHT in pulse amplitude regulation. LH pulse frequency is not decreased despite elevated plasma T and E2, raising the possibility that DHT deficiency increased pulse frequency that was normalized by increased T and/or E2. In conclusion, studies of LH pulsatility in subjects with 5 alpha RD suggest a role for DHT in the modulation of LH.

The chromosome periphery during mitosis

A complex structure, visible by electron microscopy, surrounds each chromosome during mitosis. The organization of this structure is distinct from that of the chromosomes and the cytoplasm. It forms a perichromosomal layer that can be isolated together with the chromosomes. This layer covers the chromosomes except in centromeric regions. The perichromosomal layer includes nuclear and nucleolar proteins as well as ribonucleoproteins (RNPs). The list of proteins and RNAs identified includes nuclear matrix proteins (perichromin, peripherin), nucleolar proteins (perichro-monucleolin, Ki-67 antigen, B23 protein, fibrillarin, p103, p52), ribosomal proteins (S1) and snRNAs (U3 RNAs). Only limited information is available about how and when the perichromosomal layer is formed. During early prophase, the proteins extend from the nucleoli towards the periphery of the nucleus. Thin cordon-like structures reach the nuclear envelope delimiting areas in which chromosomes condense. At telophase, the proteins are associated with the part of the chromosomes remaining condensed and accumulate in newly formed nucleoli in regions where chromatin is already decondensed. The perichromosomal layer contains several different classes of proteins and RNPs and it has been attributed various roles: (1) in chromosome organization, (2) as a barrier around the chromosomes, (3) involvement in compartmentation of the cells in prophase and telophase and (4) a binding site for chromosomal passenger proteins necessary to the early process of nuclear assembly.

Fate of specific nucleolar perichromosomal proteins during mitosis: cellular distribution and association with U3 snoRNA

In mammalian cells, the nucleoli disintegrate during mitosis and some nucleolar proteins disperse at the periphery of all chromosomes forming a novel class of chromosomal passenger proteins. The nucleolar components which participate in the formation of this perichromosomal layer have been investigated to elucidate the role of these perichromosomal proteins in the assembly and disassembly of the nucleoli. i) Electron microscopy immunolabelling reveals that these proteins are predominantly located in the granular component of the nucleoli during interphase. ii) Immunoprecipitation data suggest that they are distributed at the chromosome periphery in association with U3 small nucleolar RNA (snoRNA). In addition, the distribution of U3 snoRNA visualized by in situ hybridization, is similar to that observed for the perichromosomal proteins. iii) In cells which possess a nucleolar remnant during mitosis, U3 snoRNA and perichromosomal proteins were found both in the perichromosomal layer and in the nucleolar remnant. iv) Some of these proteins are conserved from yeast to man such as fibrillarin and a protein of 52 kDa. v) The location of these proteins observed in yeast by confocal microscopy shows that they are not dispersed during mitosis. Their partition between the two daughter cells is performed by scission of nucleolar structures forming a rod during the budding process. Therefore RNP complexes related to the processing steps of ribosome biogenesis in mammalian cells quit the nucleolus in late G2 and associate with the chromosome periphery until late telophase. They associate in the perichromosomal layer in human and PtK1 cells and both in the perichromosomal layer and the nucleolar remnant in CHO cells.

The androgen control of sebum production. Studies of subjects with dihydrotestosterone deficiency and complete androgen insensitivity

To evaluate the androgen control of sebum, subjects with complete androgen insensitivity and male pseudohermaphrodites with inherited 5 alpha-reductase deficiency and decreased dihydrotestosterone (DHT) production had sebum production studied. A hydrophobic polymeric film applied to the forehead was used to measure sebum production through the use of air filled micropores. Sebum scores of normal preadrenarchal children (ages 2-6), and normal age-matched adult males and females, were studied as well as males treated with the 5 alpha-reductase inhibitor, finasteride, for benign prostatic hyperplasia who were studied at baseline and after drug therapy. Androgen insensitive subjects had no sebum production by this methodology, and the results were identical to preadrenarchal children. In contrast, adult male pseudohermaphrodites with 5 alpha-reductase deficiency and a selective decrease in DHT production had sebum production scores identical to normal age-matched males. Males with benign prostatic hyperplasia treated with the 5 alpha-reductase inhibitor, finasteride, to lower DHT levels did not decrease the sebum score from baseline values. The lack of demonstrable sebum in androgen-insensitive subjects clearly demonstrates the absolute androgen control of sebum production. The DHT dependency of the sebaceous gland, however, could not be demonstrated in this study. Two 5 alpha-reductase isoenzymes 1 and 2, have been described. 5 alpha-reductase-2 is the gene responsible for inherited 5 alpha-reductase deficiency. Although the degree of inhibition of DHT in utero and in adulthood in male pseudohermaphrodites with a defect in 5 alpha-reductase-2 enzyme activity caused severe impairment of external genital and prostate differentiation and decreased facial and body hair, it had no demonstrable effect on sebaceous gland development or function. Furthermore, lowering DHT levels in adulthood had no effect on sebum production. If the gland is rich in the enzyme 5 alpha-reductase-2, it is proposed that the sebaceous gland is either exquisitely sensitive to DHT, requiring only small amounts for normal development and function, or that male levels of testosterone compensate for DHT and maintain normal sebaceous gland activity throughout life. It is also possible that 5 alpha-reductase-1 is the enzyme of the sebaceous gland and is unaffected in the inherited condition and by finasteride.

Normative data for the steroidogenic response of mineralocorticoids and their precursors to adrenocorticotropin in a healthy pediatric population

The responses of mineralocorticoids and their precursors 1 h after a 0.25-mg bolus of ACTH has not previously been established in infancy or childhood. We report the steroidogenic responses of pregnenolone, progesterone (Prog), deoxycorticosterone (DOC), corticosterone (B), 18-hydroxycorticosterone (18OHB), and aldosterone (A) measured 1 h after a 0.25-mg bolus of ACTH in 102 healthy children who were divided into 5 age groups: group 1 (< 1 yr; n = 22), group 2 (1-5 yr; n = 22), group 3 (6-12 yr; n = 15), group 4 (early to midpuberty; n = 21), and group 5 (late puberty; n = 22). Baseline pregnenolone levels were constant throughout childhood; however, there was a significant fall in the stimulated level after the first year of life (group 1 vs. 2, P < 0.0125). Baseline Prog levels rose significantly with the onset of puberty (group 3 vs. 4, P < 0.0125), but levels did not increase after ACTH stimulation during puberty. Both baseline and stimulated levels of Prog, DOC, and 18OHB were significantly higher in group 3 males than in group 3 females (P < 0.05). Stimulated levels of DOC and corticosterone were constant during childhood, the only exception being the fall in the stimulated level of both steroids with the onset of puberty in males (group 3 vs. 4, P < 0.0125). The baseline level of 18OHB also fell with the onset of puberty in males (P < 0.0125), but a similar fall was not seen in females or in the stimulated level of 18OHB in either sex. The stimulated aldosterone level was higher in group 1 males than in group 2 males (P < 0.0125); a similar difference was not observed in females. The differences that we observed confirm the importance of specific age- and sex-related reference data when patients with possible abnormalities of mineralocorticoid synthesis are evaluated.

Prostate visualization studies in males homozygous and heterozygous for 5 alpha-reductase deficiency

Male pseudohermaphrodites with 5 alpha-reductase deficiency have ambiguous genitalia and nonpalpable prostates on rectal examination, suggesting the dihydrotestosterone dependency of these structures. To clearly delineate the status of the prostate, male pseudohermaphrodites with 5 alpha-reductase deficiency had transrectal sonography of the prostate performed, and the results were compared to that of age-matched male controls. In six male pseudohermaphrodites, magnetic resonance imaging studies of the prostate were also performed. Heterozygote fathers also had transrectal sonography of the prostate performed and the results compared to age-matched controls. The prostates of the male pseudohermaphrodites appeared as platelike soft tissue structures posterior to the urethra on both prostatic ultrasound and magnetic resonance imaging. Prostatic volume, as determined on prostatic ultrasound by two different methods, was significantly smaller (approximately one-tenth) than the volume of age-matched controls. Transurethral ultrasound guided biopsy of the prostate in two affected subjects revealed stromal tissue. These results correlate with undetectable prostate-specific antigen in affected subjects, suggesting atrophic epithelium or lack of epithelial differentiation. This study demonstrates the dihydrotestosterone dependence of the prostate for normal differentiation and growth. The presence of some prostatic tissue in the male pseudohermaphrodites may be due to the fact that there is a decrease and not an absence of 5 alpha-reductase activity, and/or that the increased level of testosterone in subjects with this condition partially compensates for the decreased level of dihydrotestosterone. There was no difference, however, in prostate size between heterozygous fathers and age-matched control males. The heterozygote fathers had dihydrotestosterone production sufficient for normal prostate growth and development.

Relocation of nucleolar proteins around chromosomes at mitosis. A study by confocal laser scanning microscopy

The behaviour of nucleolar antigens known to associate with chromosomes at mitosis was investigated in mammalian cells (HeLa, HEp-2, PtK1, CHO) by immunofluorescence and confocal laser scanning microscopy. Serial optical sections through mitotic cells, from prophase to telophase, were used to generate three-dimensional images of the antigen distribution. Our results indicate that, at the onset of mitosis, these antigens leave the nucleoli in a highly ordered manner to form a network extending from the nucleoli towards the nuclear envelope. The migration begins at very early prophase, when the condensation of the chromosomes is not yet visible. After completion of the migration at late prophase, the labelling is found at the chromosome periphery. The antigens remain distributed as a sheath surrounding the chromosomes from prophase to telophase. Therefore, the proteins involved in the formation of this perichromosomal layer have different behaviour than those of the prenucleolar bodies. The antigens appear to interact strongly with chromosomes, since they are not lost during chromosome isolation in hypotonic buffer. Each chromosome is entirely covered from one telomere to the other, except in the centromeric region. Thus the relocation of these nucleolar proteins does not appear to be the result of a passive accumulation at the chromosome periphery, but seems rather to be due to an active targeting to specific sites. Consequently, these proteins may have a determining function in the progression of the cells through mitosis, possibly by participating in the protection and stabilization of the chromosomes.

The ultrastructure of the chromosome periphery in human cell lines. An in situ study using cryomethods in electron microscopy

We studied the chromosome periphery in human HeLa and TG cells using cryomethods in electron microscopy. A contrasted layer of peripheral chromosomal material (PCM) was visible in cryo-ultrathin sections of mitotic cells. This PCM was composed of closely packed fibrils associated with granules. The PCM did not cover the entire chromosome surface but was found around most of the chromosomes and even between two chromatids. The organization of the PCM was not affected by colchicine treatment of mitotic cells. In cells prepared by quick-freezing, the PCM appeared to be a fibrous material at the chromosome periphery, and was also associated with granules that resembled inter-chromatin granules in size and shape. At higher magnification, direct contacts between the chromosomes and the fibrils of the PCM were observed. The cryotechniques used are known to preserve the native organization of cells. Therefore, the architecture of the perichromosomal region analysed presumably corresponds to that in vivo during mitosis. These observations show that in HeLa and TG cells, a particular structure present at the chromosome periphery in the form of PCM is persistent and ubiquitous. In addition, we showed by immunolabelling that the PCM is the specific site of accumulation of nucleolar antigens during mitosis. These two results, i.e. the identification of specific morphological structures and the compartmentation of proteins, indicate that this layer is a specific region of mitotic cells.

Identification and characterization of a new set of nucleolar ribonucleoproteins which line the chromosomes during mitosis

We investigated the perichromosomal architecture established during mitosis. Entry into mitosis brings about a dramatic reorganization of both nuclear and cytoplasmic structures in preparation for cell division. While the nuclear envelope breaks down, nuclear proteins are redistributed during chromosome condensation. Some of these proteins are found around the chromosomes, but little is known concerning their nature and function. Ten autoimmune sera were used to study the microenvironment of chromosomes and, in particular, the chromosome periphery. They were selected for their anti-nucleolar specificity and were found to recognize three nucleolar proteins that coat the chromosomes during mitosis. The distribution of these antigens was followed through the cell cycle by confocal laser scanning microscopy. The antigens dispersed very early during prophase and simultaneously with the chromosome condensation suggesting a correlation between these two processes. The antigens have apparent molecular weights of 53, 66, and 103 kDa on SDS-PAGE migration. Elution of the antibodies and immunopurification showed that they are RNA-associated proteins. The coimmunoprecipitating RNA moiety involved in these RNPs appeared to be U3, but the antigens are not related to the fibrillarin family. Therefore, small nucleolar RNPs follow the same distribution during mitosis as that described for small nuclear RNPs. Possible functions for these antigens are discussed.

Normative data for adrenal steroidogenesis in a healthy pediatric population: age- and sex-related changes after adrenocorticotropin stimulation

The normal response to a single 0.25-mg dose of ACTH-(1-24) is not well established in infancy or childhood. We report the adrenal steroidogenic responses of 17-hydroxypregnenolone (17OH Preg), 17-hydroxyprogesterone (17OH Prog), 11-deoxycortisol, cortisol, deoxycorticosterone, dehydroepiandrosterone (DHEA), DHEA sulfate, androstenedione (A'dione), and testosterone in 102 healthy children who were divided into 5 groups: group 1 (less than 1 yr old; n = 22), group 2 (1-5 yr old; n = 22), group 3 (6-12 yr old; n = 15), group 4 (early-midpuberty; n = 21), and group 5 (late puberty; n = 22). Baseline and stimulated levels of 17OH Preg were significantly higher in group 1 infants than in group 2 children (P less than 0.01). Baseline levels of 17OH Prog increased in late puberty (P less than 0.01). Baseline and stimulated levels of DHEA rose in late puberty (group 5 vs. group 3, P less than 0.01). DHEA levels in late pubertal females were higher than those in their male counterparts (P less than 0.01). DHEA sulfate levels did not change after ACTH administration in any age group. Baseline and stimulated levels of A'dione rose significantly before the onset of puberty in female children (group 2 vs. group 3, P less than 0.01). The calculated ratio of 17OH Preg/17OH Prog in group 1 was significantly higher than that in other groups of children (P less than 0.01). The calculated, baseline DHEA/A'dione ratio was higher in group 1 than in older children (P less than 0.01). Stimulated ratios were higher in late pubertal females than in males (P less than 0.01). In both sexes baseline and stimulated ratios of 17OH Prog/deoxycorticosterone increased in puberty, such that late pubertal children had higher levels than prepubertal children (P less than 0.01). These data confirm the need for interpretation ACTH stimulation test data to be based upon age- and sex-specific norms.

Cognitive abilities in androgen-insensitive subjects: comparison with control males and females from the same kindred

To determine the effect of androgen insensitivity on cognitive abilities, subjects with the syndrome of complete androgen insensitivity (AI) were compared to control males and females from the same kindred on the Spanish version of the Wechsler Adult Intelligence Scale (WAIS). All subjects had similar sociocultural backgrounds and only right-handed subjects were used in the primary analysis. This design was chosen to diminish the effect of critical variables on test performance, thereby highlighting the effect of androgen unresponsiveness on cognition. The results indicated that control males and females were superior to androgen insensitive subjects on the Perceptual Organization factor, which included five visuospatial subtests. Separate analysis of these subtests revealed that males performed significantly better than females on Block Design, Picture Completion, and Object Assembly, and better than androgen insensitive subjects on all five subtests. Females were superior to androgen insensitive subjects on four subtests (Block Design, Picture Completion, Digit Symbol, and Picture Arrangement). Despite the small sample size, when female siblings were compared to their AI sisters, they were also superior on these four visuospatial subtests. The difference between the Verbal Comprehension and Perceptual Organization factors was greatest in androgen-insensitive subjects, while control males demonstrated the least difference. Females and AI subjects did not differ from one another on the Freedom from Distractibility factor nor on the subtests comprising it, but their performances were poorer than control males. None of the groups differed significantly on Full Scale IQ, Verbal IQ, the Verbal Comprehension factor, or any subtests included in this category.(ABSTRACT TRUNCATED AT 250 WORDS)

DNA linkage analysis and studies of the androgen receptor gene in a large kindred with complete androgen insensitivity

DNA linkage analysis of the X chromosome and studies with cDNA probes specific for the androgen receptor gene were performed on the largest known kindred with the syndrome of complete androgen insensitivity. The affected subjects (XY) have absent binding of dihydrotestosterone to the androgen receptor (the receptor negative form of androgen insensitivity). In this kindred there was maternal transmission of the gene, with all affected males expressing complete genital feminization. Linkage analysis studies were conducted with two DNA probes, DXS1 and PGK1, localized to the Xq11-Xq13 region of the long arm of the X chromosome near the centromere. The results demonstrate linkage to the markers in the order of DXS1-(AR; PGK1), thus localizing the AR gene to an area between Xq11 and Xq13. Three cDNA probes that span various parts of the androgen receptor gene, including the DNA and steroid binding domain, were used to evaluate the androgen receptor gene in normal individuals, carrier mothers, and affected subjects. Identical restriction fragment patterns were found in all three groups studied. Thus the androgen receptor gene was present in affected subjects without detectable DNA polymorphism at the androgen binding domain. Therefore, despite complete absence of binding to the androgen receptor, the defect in the androgen receptor gene in this kindred is not the result of a gene deletion. The results point to a mutation or a small insertion/deletion as the probable cause of the syndrome.