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Biomedical subjects

P M Bouloux

Publications and source records attributed to P M Bouloux.

At least 19 recordsLinked to original sources
PubMed2001

Molecular modelling and experimental studies of mutation and cell-adhesion sites in the fibronectin type III and whey acidic protein domains of human anosmin-1.

Anosmin-1, the gene product of the KAL gene, is implicated in the pathogenesis of X-linked Kallmann's syndrome. Anosmin-1 protein expression is restricted to the basement membrane and interstitial matrix of tissues affected in this syndrome during development. The anosmin-1 sequence indicates an N-terminal cysteine-rich domain, a whey acidic protein (WAP) domain, four fibronectin type III (FnIII) domains and a C-terminal histidine-rich region, and shows similarity with cell-adhesion molecules, such as neural cell-adhesion molecule, TAG-1 and L1. We investigated the structural and functional significance of three loss-of-function missense mutations of anosmin-1 using comparative modelling of the four FnIII and the WAP domains based on known NMR and crystal structures. Three missense mutation-encoded amino acid substitutions, N267K, E514K and F517L, were mapped to structurally defined positions on the GFCC' beta-sheet face of the first and third FnIII domains. Electrostatic maps demonstrated large basic surfaces containing clusters of conserved predicted heparan sulphate-binding residues adjacent to these mutation sites. To examine these modelling results anosmin-1 was expressed in insect cells. The incorporation of the three mutations into recombinant anosmin-1 had no effect on its secretion. The removal of two dibasic motifs that may constitute potential physiological cleavage sites for anosmin-1 had no effect on cleavage. Peptides based on the anosmin-1 sequences R254--K285 and P504--K527 were then synthesized in order to assess the effect of the three mutations on cellular adhesion, using cell lines that represented potential functional targets of anosmin-1. Peptides (10 microg/ml) incorporating the N267K and E514K substitutions promoted enhanced adhesion to 13.S.1.24 rat olfactory epithelial cells and canine MDCK1 kidney epithelial cells (P<0.01) compared with the wild-type peptides. This result was attributed to the introduction of a lysine residue adjacent to the large basic surfaces. We predict that two of the three missense mutants increase the binding of anosmin-1 to an extracellular target, possibly by enhancing heparan sulphate binding, and that this critically affects the function of anosmin-1.

Amino Acid Motifs↗
PubMed2001

The sweating apparatus in growth hormone deficiency, following treatment with r-hGH and in acromegaly.

Adult growth hormone deficient patients are known to exhibit reduced sweating and their ability to thermoregulate is diminished. Treatment of these patients with recombinant human growth hormone (r-hGH) is claimed to reverse these abnormalities. We have investigated this claim, as well as the mechanism underlying these altered sweating responses in GH-deficient patients as part of a placebo-controlled study on the effects of 6-12 months r-hGH therapy. Skin biopsies were obtained from these subjects and changes in morphology and innervation parameters for the eccrine sweat glands were examined. These included histochemistry for acetylcholinesterase (AChE) and immunohistochemistry for the neuropeptide vasoactive intestinal polypeptide (VIP) and for PGP9.5, a general neuronal marker. Sweat gland acinar size and periacinar innervation were measured by computerised image analysis. The patients underwent pilocarpine iontophoresis sweat rate tests and their serum insulin-like growth factor 1 (IGF-1) levels were assessed. Since active acromegaly involves excess GH secretion and hyperhidrosis, skin biopsies and sweat tests were also carried out on a group of these patients, as well as on control subjects. We have demonstrated a sweating defect in adult GH-deficiency which is accompanied by a reduction in AChE and VIP levels in the nerve supply to sweat glands. Following r-hGH therapy, an increase in AChE and VIP staining is seen in the sudomotor nerves accompanied by restoration of sweat rates and serum IGF-1 levels. Hence, normalization of sweat gland function includes recovery of sudomotor synapse constituents. A trophic effect of GH on sweat gland epithelium and/or on the associated nerves is proposed, supported by the observation that in acromegaly the size of sweat gland acini and the density of innervation to the sweat glands was greater than in controls.

Acetylcholinesterase↗
PubMed2001

Idiopathic gonadotrophin deficiency: genetic questions addressed through phenotypic characterization.

OBJECTIVE: The association of idiopathic hypogonadotrophic hypogonadism (IHH) with congenital olfactory deficit defines Kallmann's syndrome (KS). Although a small proportion of IHH patients have been found to harbour defined genetic lesions, the genetic basis of most IHH cases remains to be elucidated. Genes currently recognized to be involved comprise KAL (associated with X-linked-KS), the GnRH receptor (associated with resistance to GnRH therapy), DAX 1 (associated with adrenohypoplasia congenita) and three loci also associated with obesity, leptin (OB), leptin receptor (DB) and prohormone convertase (PC1). Because of the rarity of the condition and the observation that patients are almost universally infertile without assistance, familial transmission of IHH is encountered infrequently and pedigrees tend to be small. This has constrained the ability of conventional linkage studies to identify other candidate loci for genetic IHH. We hypothesized that a systematic clinical evaluation of a large patient sample might provide new insights into the genetics of this rare disorder. Specifically, we wished to examine the following propositions. First, whether normosmic (nIHH) and anosmic (KS) forms of IHH were likely to be genetically discrete entities, on the basis of quantitative olfactory testing, analysis of autosomal pedigrees and the prevalence of developmental defects such as cryptorchidism and cleft palate. Second, whether mirror movements and/or unilateral renal agenesis were specific phenotypic markers for X-linked-KS. DESIGN AND PATIENTS: We conducted a clinical study of 170 male and 45 female IHH patients attending the endocrinology departments of three London University teaching hospitals. Approximately 80% of data were obtained from case records and 20% collected prospectively. Parameters assessed included olfaction, testicular volume, family history of hypogonadism, anosmia or pubertal delay, and history or presence of testicular maldescent, neurological, renal or craniofacial anomalies. Where possible, the clinical information was correlated with published data on genetic analysis of the KAL locus. RESULTS: Olfactory acuity was bimodally distributed with no evidence for a spectrum of olfactory deficit. Testicular volume, a marker of integrated gonadotrophin secretion, did not differ significantly between anosmic and normosmic patients, at 2.0 ml and 2.2 ml, respectively. Nevertheless, the prevalence of cryptorchidism was nearly three times greater in anosmic (70.3%, of which 75.0% bilateral) than in normosmic (23.2%, of which 43.8% bilateral) patients. Individuals with nIHH, eugonadal isolated anosmia and/or KS were observed to coexist within 6/13 autosomal IHH pedigrees. On three occasions, fertility treatment given to an IHH patient had resulted in the condition being transmitted to the resulting offspring. Mirror movements and unilateral renal agenesis were observed in 24/98 and 9/87 IHH patients, respectively, all of whom were identifiable as X-KS males on the basis of pedigree analysis and/or defective KAL coding sequence. Abnormalities of eye movement and unilateral sensorineural deafness were observed in 10/21 and 6/111 KS patients, respectively, but not in nIHH patients. DISCUSSION: Patients with IHH are almost invariably either anosmic (KS) or normosmic (nIHH), rather than exhibiting intermediate degrees of olfactory deficit. Moreover, the prevalence of cryptorchidism is nearly three times greater in KS than in nIHH despite comparable testicular volumes, suggesting a primary defect of testicular descent in KS independent of gonadotrophin deficiency. Disorders of eye movement and hearing appear only to occur in association with KS. Taken together, these findings indicate a clear phenotypic separation between KS and nIHH. However, pedigree studies suggest that autosomal KS is an heterogeneous condition, with incomplete phenotypic penetrance within pedigrees, and that some cases of autosomal KS, nIHH and even isolated anosmia are likely to have a common genetic basis. The prevalences of anosmia, mirror movements and unilateral renal agenesis among X-KS men are estimated to be 100, 85 and 31%, respectively. In sporadic IHH, mirror movements and unilateral renal agenesis are 100% specific phenotypic markers of de novo X-KS. By comparison, only 7/10 X-KS families harboured KAL coding defects. Clinical ascertainment, using mirror movements, renal agenesis and ichthyosis as X-KS-specific phenotypic markers, suggested that de novo X-KS was unlikely to comprise more than 11% of sporadic cases. The majority of sporadic KS cases are therefore presumed to have an autosomal basis and, hence, the preponderance of affected KS males over females remains unexplained, though reduced penetrance in women would be a possibility.

Adolescent↗
PubMed2001

First human exposure to FSH-CTP in hypogonadotrophic hypogonadal males.

BACKGROUND: This is the first report of human exposure to the novel compound follicle stimulating hormone (FSH)-C-terminal peptide (CTP) 'FSH-CTP' (Org 36286), a long-acting recombinant FSH like substance, consisting of the alpha-subunit of human FSH and a hybrid beta-subunit. The latter is composed of the beta-subunit of human FSH and the C-terminus part (CTP) of the beta-subunit of human chorionic gonadotrophin (HCG). METHODS: In this phase I, non-blind, multi-centre study, 13 hypogonadotrophic hypogonadal male subjects were enrolled to test the safety of FSH-CTP in terms of antibody formation in humans. Furthermore, the pharmacokinetic profile of this new compound was determined. Subjects were injected four times with 15 microg FSH-CTP with an interval of approximately 4 weeks between each injection. RESULTS: No drug related (serious) adverse events occurred. No antibodies against FSH-CTP or chinese hamster ovary (CHO)-cell derived proteins were detected and measurement of local tolerance demonstrated that s.c. administration of FSH-CTP is well tolerated and no increase in intensity of injection-site responses was observed after repeated exposure to FSH-CTP. After the first and third injection, FSH-CTP serum concentrations were determined. Overall mean (+/- SD) C(max) was 0.426 (+/- 0.116) ng/ml, mean t(1/2) and AUC(0-infinity) were 94.7 (+/- 26.2) h and 81.5 (+/- 18.8) ng.h/ml respectively. Compared with recFSH (Puregon), the half life of FSH-CTP was increased 2-3 times. Following the first and third injection a clear rise in serum inhibin-B concentrations were observed. CONCLUSIONS: The use of FSH-CTP is safe and does not lead to detectable formation of antibodies. Furthermore, the pharmacokinetic and dynamic profile of FSH-CTP may lead to the development of new, more convenient regimens for the treatment of male and female infertility.

Adult↗
PubMed2001

Multicystic dysplastic kidney and Kallmann's syndrome: a new association?

BACKGROUND: Kallmann's syndrome is characterized by anosmia and hypogonadotrophic hypogonadism. Radiographic studies of teenagers and older subjects with the X-linked form of the syndrome have shown that up to 40% have an absent kidney unilaterally. Although this has been attributed to renal "agenesis", a condition in which the kidney fails to form, little is known about the appearance of the developing urinary tract either pre- or post-natally in individuals with Kallmann's syndrome. METHODS: We describe two brothers who had features of Kallmann's syndrome, most probably of the X-linked variety, who both had a major urinary-tract malformation detected before birth. RESULTS: The brothers were found to have unilateral multicystic dysplastic kidneys on routine antenatal ultrasound scanning and both underwent surgical nephrectomy of these organs post-natally. Immunohistochemical studies on the younger sibling revealed hyperproliferative dysplastic kidney tubules which overexpressed PAX2, a potentially oncogenic transcription factor, and BCL2, a cell-survival factor, surrounded by metaplastic, alpha smooth-muscle actin-positive stroma: similar patterns have been observed in patients with non-syndromic multicystic dysplastic kidneys. CONCLUSIONS: Our results describe a new type of urinary-tract malformation associated with Kallmann's syndrome. However, since multicystic kidneys tend to involute, only when more Kallmann's syndrome patients are screened in utero or in early childhood using structural renal scans, will it be possible to establish whether multicystic kidney disease is a bona-fide part of the syndrome.

Child, Preschool↗
PubMed2000

Optimisation of growth hormone production by muscle cells using plasmid DNA.

The production of peptide hormones by skeletal muscle tissue is a promising area of gene therapy. Skeletal muscle myogenesis can be induced in vitro, resulting in the fusion of mononucleate myoblasts to form multinucleate myotubes, and delivery vectors are first tested in vitro. C2C12 myoblasts transfected with pcDNA3-GH, which used the human cytomegalovirus (CMV) promoter, secreted immunoreactive GH with comparable biological activity to pituitary GH. Mouse myeloid leukaemia cells, which express the mouse GH receptor were used for the bioassay, and activation of these cells by GH was measured by a colorimetric microculture tetrazolium assay. Cells were incubated with a tetrazolium salt (MTS) and an intermediate electron acceptor (phenazine methosulphate, PMS), and formazan production was measured as optical density (O.D.) at 490 nm. The efficiencies of several plasmid expression vectors were compared in differentiated and non-differentiated muscle cells, as a function of bioactive GH secreted by the transfected cells. Ten-day differentiated C2C12 myotubes transfected with pcDNA3E-GH, which used the CMV promoter and a rat myosin light chain enhancer element, secreted significantly more biologically active GH than myotubes transfected with pcDNA3-GH (0.82 O.D. units+/-0.06 vs 0.57+/-0.05 respectively, P<0.001). This was consistent with reduced CMV promoter activity in myotubes. Myoblasts transfected with pcDNA3-GH secreted more bioactive GH than 10-day transfected myotubes (1.1+/-0. 1 vs 0.77+/-0.07 respectively). However, the responses were indistinguishable (both 1.0+/-0.09) if both the myotubes and myoblasts had been transfected with pcDNA3E-GH. Substitution of the vector pMHLC-GH, which used a muscle-specific truncated rabbit myosin heavy chain promoter, and the myosin enhancer resulted in a marked decrease in the responses to the conditioned medium from fused myotubes compared with the vectors pcDNA3-GH and pcDNA3E-GH (0. 24+/-0.02 vs 0.57+/-0.05 vs 0.82+/-0.06 respectively). We concluded that the combination of CMV promoter and myosin light chain enhancer in pcDNA3E-GH had the greatest expression efficiency of the several plasmid vectors which we investigated.

Animals↗
PubMed1999

Kallmann's syndrome: mirror movements associated with bilateral corticospinal tract hypertrophy.

OBJECTIVE: To investigate the etiology of mirror movements in patients with X-linked Kallmann's syndrome (xKS) through statistical analysis of pooled white matter data from structural MR images. BACKGROUND: Mirror movements occur in 85% of xKS patients. Previous electrophysiologic studies have suggested an abnormal ipsilateral corticospinal tract projection in xKS patients exhibiting mirror movements. However, an alternative hypothesis has proposed a functional lack of transcallosal inhibitory fibers. METHODS: T1-weighted brain scans were normalized into stereotaxic space with segregation of gray and white matter to allow comparison of pooled white matter data on a voxel-by-voxel basis using SPM-96 software. Nine xKS patients were compared with two age-matched groups of nonmirroring individuals: nine patients with autosomal Kallmann's syndrome (aKS) and nine age-matched normal (healthy) men. RESULTS: Hypertrophy of the corpus callosum was found in both Kallmann's syndrome groups: the anterior and midsection in xKS, and the genu and posterior section in aKS. Bilateral hypertrophy of the corticospinal tract was found only in the group of xKS patients exhibiting mirror movements. SPM analysis was validated by an independent region of interest analysis of corpus callosum size. CONCLUSION: Although morphometry on its own cannot determine the cause of mirror movements, the specific finding of a hypertrophied corticospinal tract in xKS is consistent with electrophysiologic evidence suggesting that mirror movements in xKS result from abnormal development of the ipsilateral corticospinal tract fibers.

Adult↗
PubMed1999

Kallmann's syndrome: is it always for life?

OBJECTIVE: Kallmann's syndrome (KS) is defined by the association of olfactory deficit with irreversible, congenital gonadotrophin deficiency (IHH). We present evidence for the existence of a variant form of KS, in which endogenous gonadotrophin secretion recovers spontaneously in later life. DESIGN: Longitudinal clinical study. PATIENTS: Five men with anosmia or severe hyposmia, who originally presented in their late teens or early twenties as a result of severe pubertal delay and were thus presumed to have KS. RESULTS: Spontaneous onset of endogenous gonadotrophin secretion, evidenced by progressive normalization of testicular volume and of serum testosterone concentration, occurred in these men over a period of years following the initial diagnosis. CONCLUSIONS: This variant form of Kallman's syndrome is not well recognized and may well be under-diagnosed. Once full virilization has been induced, males with congenital gonadotrophin deficiency whose testes have significantly increased in size should be reassessed, off androgen replacement therapy, to identify those who no longer require treatment.

Adolescent↗
PubMed1999

Gordon Holmes spinocerebellar ataxia: a gonadotrophin deficiency syndrome resistant to treatment with pulsatile gonadotrophin-releasing hormone.

The Gordon Holmes spinocerebellar ataxia syndrome (GHS) is associated with idiopathic hypogonadotrophic hypogonadism (IHH). There are conflicting reports in the literature as to whether the primary neuroendocrine defect is of hypothalamic GnRH secretion, as with most causes of IHH, or of pituitary resistance to GnRH action. Because of the anatomical inaccessibility of the hypophyseal portal circulation, direct measurement of GnRH levels in human subjects is not possible. Previous investigators have attempted to unravel this problem through the use of GnRH stimulation tests and the limitations of this approach may explain the differing results obtained. We used the more physiological approach of treating a male GHS patient for four weeks with GnRH, 7-10 microg/pulse, delivered subcutaneously at 90 minute frequency via a portable minipump. This therapy failed to induce any rise in plasma gonadotrophin and testosterone concentrations. By contrast, eight weeks treatment with exogenous gonadotrophins maintained physiological plasma testosterone concentrations and induced testicular enlargement with induction of spermatogenesis. The data indicate that the primary endocrinopathy in GHS is of pituitary gonadotrophin secretion and not of hypothalamic GnRH. Moreover, the patient did not harbour any mutation of the GnRH receptor gene. Two clinical observations are consistent with progressive involution of gonadotrophic function, rather than a congenital gonadotrophin deficiency. First, the patient's development was arrested at early mid-puberty at the time of original presentation and, second, effective spermatogenesis was induced extremely rapidly during gonadotrophin treatment, suggesting prior exposure of the testes to FSH. Both spinocerebellar ataxia and pituitary dysfunction might thus have been in evolution since late childhood.

Adult↗
PubMed1999

Using skeletal muscle as an artificial endocrine tissue.

Gene transfer into muscle tissue is currently being developed as a method for the production, secretion and delivery of therapeutic proteins. This methodology has been used to produce a variety of physiologically active proteins and may ultimately be applied to the treatment of several diseases. In this review, we consider several applications of this methodology and discuss approaches for modulating therapeutic protein production and secretion from muscle, using growth hormone as an example. In addition, factors limiting the effectiveness of muscle gene transfer are also discussed, as these shall determine the efficacy of muscle gene transfer when applied to humans.

Gene Expression Regulation↗
PubMed1998

Contrasting expression of KAL in cell-free systems: 5' UTR and coding region structural effects on translation.

We investigated the expression of two different X-linked Kallmann (KAL) gene cDNAs in two different cell-free systems using rabbit reticulocyte lysate: (system A) transcription/translation coupled and (system B) noncoupled. System A yielded a single band of 76 kDa corresponding to anosmin-1, the expected full-length gene product, and upon addition of canine microsomal membranes produced a 85-kDa glycosylated form. System B did not produce any detectable protein band despite the expression of a beta-galactosidase-positive control gene. The first 179 bases of the coding sequence are 74% GC-rich and showed the potential to form imperfect hairpin structures, which in part may explain the translation inhibition of KAL in system B. This has further led us to speculate that coupling transcription to translation may either be preventing translating-inhibiting hairpin formation or be compensating for the lack of certain tissue-specific proteins in reticulocyte lysate that are essential in overcoming inhibitory hairpins during translation. Substitution of the 5'-UTR with an encephalomyocarditis virus internal ribosomal entry site (EMCV IRES) sequence resulted paradoxically in a lower yield of anosmin-1, suggesting that elements in the 5'UTR may be necessary for maintaining a "normal" level of expression. The use of KAL and luciferase reporters (containing different 5'UTRs) demonstrated that the native KAL 5' UTR is not involved in translational efficiency. However, this sequence may influence faithful translation initiation. Theoretical RNA conformation data imply that effective EMCV IRES usage with KAL may require favorable pairing between the IRES and unidentified sequences within the 5' coding region of the gene. This work provides a foundation both for the investigation of KAL regulation and for the characterization of its function.

Animals↗
PubMed1998

Proteinuria, hypertension and chronic renal failure in X-linked Kallmann's syndrome, a defined genetic cause of solitary functioning kidney.

BACKGROUND: Anosmia and hypogonadotrophic hypogonadism are the classic features of X-linked Kallmann's syndrome, a disorder caused by mutations of KAL, a gene expressed during kidney and brain development. About a third of patients have a solitary functioning kidney, but little is known about their renal morbidity. METHODS: We studied seven patients aged 22-35 years with X-linked Kallmann's syndrome and a solitary functioning kidney. RESULTS: Two patients developed significant proteinuria associated with mild to moderate arterial hypertension in the second to third decades of life. In one, proteinuria and renal impairment preceded the appearance of hypertension, and the disorder progressed to chronic renal failure. The remaining five patients had normal plasma creatinine concentrations and no significant proteinuria although four had borderline systolic and/or diastolic hypertension. In two sets of patients from the same kindreds, there was a striking discordance for the occurrence of renal morbidity. CONCLUSIONS: All patients with X-linked Kallmann's syndrome should be screened for renal malformations, and those with solitary kidneys require life-long follow-up to detect hypertension, proteinuria and renal failure.

Adult↗
PubMed1998

The diagnosis of childhood growth hormone insufficiency and growth hormone resistance.

Growth hormone insufficiency (GHI) is an uncommon though treatable cause of retarded growth velocity and short stature in childhood, the diagnosis generally requiring the demonstration of a subnormal growth hormone (GH) response to a physiological or pharmacological stimulus. Physiological and pharmacological GH release is a continuous variable and the relationship between spontaneous GH secretion and height velocity is asymptotic. Cut-off points for defining GH insufficiency are largely derived from adult observations, but have been extrapolated to children, for whom normative data are relatively scanty. There is no absolute cut-off that discriminates between normal and abnormal GH response. Moreover, poor reproducibility, sensitivity and specificity of the many dynamic tests available, particularly when performed in the very young child or in early adolescence, together with the confounding effects of assay performance, further weaken the diagnostic efficiency of biochemical investigations. Between 20-40% of children retested at the completion of GH therapy demonstrate a normal GH response to a provocative stimulus. Such limitations mitigate against over-reliance on GH provocation tests in diagnosis, and further emphasize the importance of careful auxology in evaluating the short child.

Child↗
PubMed1998

Somatuline LA: a new treatment for acromegaly.

Somatostatin analogues have become well established as treatment for acromegaly. However, to ensure growth hormone (GH) levels are sufficiently suppressed, thrice daily subcutaneous injections are required. The introduction of Somatuline LA, a long acting formulation which controls plasma GH levels for up to 14 days and improves acromegaly symptoms, is likely to improve patient compliance and quality of life.

Acromegaly↗