Plasma leptin levels after biliopancreatic diversion: dissociation with body mass index

Human obesity is associated with increased leptin levels, related to body composition and fat mass (FM). Insulin has been suggested to be a regulator of in vivo leptin secretion. To further investigate the relationships between insulin and leptin levels in human obesity, we have studied 10 obese females, aged 26-57 yr [body mass index (BMI), 42.9+/-6.3], successfully treated by biliopancreatic (BPD) diversion, in an early postoperative period (2 months after surgery, post-BPD I; BMI, 37.2+/-7.5) and a late postoperative period (16-24 months after surgery; BMI, 27.6+/-3.96). Fourteen normal female subjects (18-59 yr; BMI, 27.9+/-1.4 kg/m2) were studied as controls. In pre-BPD obese subjects, leptin levels were higher than those in controls (60.5+/-18.8 vs. 28.7+/-4.8 ng/mL; P<0.001). BMI and insulin levels were also significantly greater (P<0.0001 and P<0.03, respectively). After surgery, the three parameters considered significantly decreased (P = 0.0007 for BMI, P<0.0001 for leptin, and P = 0.038 for insulin, using Friedman's test for repeated data). Concerning the correlation between leptin and FM in our patients, control subjects and pre-BPD subjects confirmed the correlation found in the general population (r = 0.78; P<0.01). On the contrary, post-BPD patients at 2 months lay outside the general correlation between FM and leptin; in fact, patients with low leptin levels still had a high FM. Moreover, in the post-BPD patients there was no longer a significant correlation between FM and leptin. Concerning the correlation between insulin and leptin levels, a significant correlation was present in control subjects and pre-BPD patients (r = 0.46; P<0.05). Using correlation analysis for repeated measures in surgically treated obese patients, a significant correlation within the subjects was present (r = 0.91; P<0.0001). After operation, BMI and leptin levels had a different pattern of decrease; leptin decreased rapidly, without correlation with BMI, indicating that body composition is not the only factor regulating leptin levels. The consistent correlation with insulin levels suggests an important interaction between these two hormones in post-BPD obese subjects.

Mutations in the gene encoding 3 beta-hydroxysteroid-delta 8, delta 7-isomerase cause X-linked dominant Conradi-Hünermann syndrome

X-linked dominant Conradi-Hünermann syndrome (CDPX2; MIM 302960) is one of a group of disorders with aberrant punctate calcification in cartilage, or chondrodysplasia punctata (CDP). This is most prominent around the vertebral column, pelvis and long bones in CPDX2. Additionally, CDPX2 patients may have asymmetric rhizomesomelia, sectorial cataracts, patchy alopecia, ichthyosis and atrophoderma. The phenotype in CDPX2 females ranges from stillborn to mildly affected individuals identified in adulthood. CDPX2 is presumed lethal in males, although a few affected males have been reported. We found increased 8(9)-cholestenol and 8-dehydrocholesterol in tissue samples from seven female probands with CDPX2 (ref. 4). This pattern of accumulated cholesterol intermediates suggested a deficiency of 3beta-hydroxysteroid-delta8,delta7-isomerase (sterol-delta8-isomerase), which catalyses an intermediate step in the conversion of lanosterol to cholesterol. A candidate gene encoding a sterol-delta8-isomerase (EBP) has been identified and mapped to Xp11.22-p11.23 (refs 5,6). Using SSCP analysis and sequencing of genomic DNA, we found EBP mutations in all probands. We confirmed the functional significance of two missense alleles by expressing them in a sterol-delta8-isomerase-deficient yeast strain. Our results indicate that defects in sterol-delta8-isomerase cause CDPX2 and suggest a role for sterols in bone development.

The COE transcription factor Collier is a mediator of short-range Hedgehog-induced patterning of the Drosophila wing

BACKGROUND

The secreted Hedgehog (Hh) proteins have been implicated as mediators of positional information in vertebrates and invertebrates. A gradient of Hh activity contributes to antero-posterior (A/P) patterning of the fly wing. In addition to inducing localised expression of Decapentaplegic (Dpp), which in turn relays patterning cues at long range, Hh directly patterns the central region of the wing.

RESULTS

We show that short-range, dose-dependent Hh activity is mediated by activation of the transcription factor Collier (Col). In the absence of col activity, longitudinal veins 3 and 4 (L3 and L4) are apposed and the central intervein is missing. Hh expression induces col expression in a narrow stripe of cells along the A/P boundary through a dual-input mechanism: inhibition of proteolysis of Cubitus-interruptus (Ci) and activation of the Fused (Fu) kinase. Col, in cooperation with Ci, controls the formation of the central intervein by activating the expression of blistered (bs), which encodes the Drosophila serum response factor (D-SRF), the activity of which is required for the adoption and maintenance of the intervein cell fate. Furthermore, col is allelic to knot, a gene involved in the formation of the central part of the wing. This finding completes our understanding of the sectorial organisation of the Drosophila wing.

CONCLUSIONS

Col, the Drosophila member of the COE family (Col/Olf-1/EBF) of non-basic, helix-loop-helix (HLH)-containing transcription factors, is a mediator of the short-range organising activity of Hh in the Drosophila wing. Our results support the idea that Hh controls target gene expression in a concentration-dependent manner and highlight the importance of the Fu kinase in this differential regulation. The high degree of evolutionary conservation of the COE proteins and the diversity of developmental processes controlled by Hh signalling raises the possibility that the specific genetic interactions depicted here may also operate in vertebrates.

Hyperornithinaemia-hyperammonaemia-homocitrullinuria syndrome is caused by mutations in a gene encoding a mitochondrial ornithine transporter

Neurospora crassa ARG13 and Saccharomyces cerevisiae ARG11 encode mitochondrial carrier family (MCF) proteins that transport ornithine across the mitochondrial inner membrane. We used their sequences to identify EST candidates that partially encode orthologous mammalian transporters. We thereby identified such a gene (ORNT1) that maps to 13q14 and whose expression, similar to that of other urea cycle (UC) components, was high in liver and varied with changes in dietary protein. ORNT1 expression restores ornithine metabolism in fibroblasts from patients with hyperammonaemia-hyperornithinaemia-homocitrullinuria (HHH) syndrome. In a survey of 11 HHH probands, we identified 3 ORNT1 mutant alleles that account for 21 of 22 possible mutant ORNT1 genes in our patients: F188delta, which is common in French-Canadian HHH patients and encodes an unstable protein; E180K, which encodes a stable, properly targeted protein that is inactive; and a 13q14 microdeletion. Our results show that ORNT1 encodes the mitochondrial ornithine transporter involved in UC function and is defective in HHH syndrome.

Hypothalamic derangement in traumatized patients: growth hormone (GH) and prolactin response to thyrotrophin-releasing hormone and GH-releasing hormone

OBJECTIVE

To study the impact of severe head injury on both basal pituitary hormone secretion and the response to exogenous synthetic hypothalamic releasing factors (TRH and GHRH) in order to evaluate sequential changes in the central control of hypophyseal secretion in the days following head injury.

DESIGN

Prospective clinical study

PATIENTS

21 comatose male patients with head injuries, each intubated and ventilated, intensively monitored and having no previous endocrine problems.

MEASUREMENTS

AND RESULTS The GH and PRL responses to TRH (200 microg iv), and the GH and PRL responses to GHRH (50 microg iv) were evaluated, respectively, on the days 1 and 16 and on days 2, 7and 15 after admission. Daily blood samples were also collected for GH, PRL, TSH, T3 and T4 evaluation. In the basal samples taken on days 2, 7 and 15, IGF-I and cortisol were also determined. Nitrogen balance was assessed daily. On the day 1, TRH increased GH levels from 9.8 +/- 2.2 to 22.4 +/- 6.5 mU/l but failed to induce GH release on day 16. The PRL response to TRH was normal. The GH peak response to GHRH was normal on the day 2 (35.7 +/- 13.9 mU/l), but was increased on days 7 and 15 (68.3 +/- 10.7 mU/l on day 7; 73.8 +/- 9.2 mU/l on day 15, P < 0.01 vs. day 2). We found a significant PRL response to GHRH during the whole period of observation. In the daily evaluation, nitrogen balance was negative in all patients from the day 1 to 5. On average, all patients reached a positive nitrogen balance on the day 8. Compared to the day 2, a statistical increase in IGF-I concentration was observed on days 7 and 15.

CONCLUSIONS

The evaluation of pituitary dynamics in the acute phase of a severe injury demonstrates an alteration of GH and PRL secretion, which correlate with the aminergic and/or peptidergic derangements. Taken together, our data suggest augmented tone of both GHRH and somatostatin in the very acute phase, while an imbalance of releasing factors is hypothesized in the following days. The metabolic consequences of this neuroendocrine pattern could be advantageous in the rapid recovery from the cascade of events produced by the trauma, as documented by the increase in IGF-1 levels and the positive nitrogen balance.

Molecular enzymology of mammalian Delta1-pyrroline-5-carboxylate synthase. Alternative splice donor utilization generates isoforms with different sensitivity to ornithine inhibition

Delta1-Pyrroline-5-carboxylate synthase (P5CS; EC not assigned), a mitochondrial inner membrane, ATP- and NADPH-dependent, bifunctional enzyme, catalyzes the reduction of glutamate to Delta1-pyrroline-5-carboxylate, a critical step in the de novo biosynthesis of proline and ornithine. We utilized published plant P5CS sequence to search the expressed sequence tag data base and cloned two full-length human P5CS cDNAs differing in length by 6 base pairs (bp) in the open reading frame. The short cDNA has a 2379-bp open reading frame encoding a protein of 793 residues; the long cDNA, generated by "exon sliding," a form of alternative splicing, contains an additional 6-bp insert following bp +711 of the short form resulting in inclusion of two additional amino acids in the region predicted to be the gamma-glutamyl kinase active site of P5CS. The long form predominates in all tissues examined except gut. We also isolated the corresponding long and short murine P5CS transcripts. To confirm the identity of the putative P5CS cDNAs, we expressed both human forms in gamma-glutamyl kinase- and gamma-glutamyl phosphate reductase-deficient strains of Saccharomyces cerevisiae and showed that they conferred the proline prototrophy. Additionally, we found expression of the murine putative P5CS cDNAs conferred proline prototrophy to P5CS-deficient Chinese hamster ovary cells (CHO-K1). We utilized stable CHO-K1 cell transformants to compare the biochemical characteristics of the long and short murine P5CS isoforms. We found that both confer P5CS activity and that the short isoform is inhibited by L-ornithine with a Ki of approximately 0.25 mM. Surprisingly, the long isoform is insensitive to ornithine inhibition. Thus, the two amino acid insert in the long isoform abolishes feedback inhibition of P5CS activity by L-ornithine.

[Goiter prevalence and urinary excretion of iodine in a sample of school age children in the city of Rome]

The aim of the study was the assessment of the urinary iodine excretion and the evaluation of thyroid volume compared with clinical examination in 1040 schoolchildren (6-14 years old), living in Rome. Mean urinary iodine excretion was 98.52 +/- 49.81 micrograms/l (median 92 micrograms/l). Thyroid enlargement, as assessed by palpation, was found to be grade 1A in 35.4% of the children, grade 1B in 9.6% and grade 2 in 0.2%. Thyroid volume, determined by ultrasound, increased with age, was significantly correlated with body surface area and was significantly higher in females, as compared to males, in the 11 and 12 years old group. Eleven children (1.9%) were negative at palpation (grade 0) but showed thyroid enlargement by ultrasound. The prevalence of goiter determined by ultrasound resulted to be 4.7%.

Effect of opioid blockade on insulin and growth hormone (GH) secretion in patients with polycystic ovary syndrome: the heterogeneity of impaired GH secretion is related to both obesity and hyperinsulinism

OBJECTIVE

To investigate the involvement of opioid tone, obesity, and hyperinsulinemia in GH secretion in women with polycystic ovary syndrome (PCOS).

DESIGN

Controlled clinical study.

SETTING

Catholic University of Sacred Heart School of Medicine in Rome, Italy.

PATIENT(S)

Twenty-two patients with PCOS and 14 healthy, normally ovulating volunteers, matched for age and body mass index.

INTERVENTION(S)

Patients underwent a GH-releasing hormone (GHRH) test and an oral glucose tolerance test before and after 4-5 weeks of treatment with 50 mg/d of naltrexone.

MAIN OUTCOME MEASURE(S)

Serum concentrations of GH, insulin, glucose, steroids, and gonadotropins, as well as the GH area under the curve (AUC-GH) and the insulin area under the curve (AUC-I), were measured before and after naltrexone treatment.

RESULT(S)

In patients with PCOS, the administration of naltrexone increased the GH response to the GHRH test without interfering with the insulin response to the oral glucose tolerance test. However, the GH response to the GHRH test was improved significantly only in lean patients with PCOS, whereas obese patients with PCOS did not show any improvement in GH secretion. In obese control subjects, the treatment reduced plasma basal insulin concentrations and increased the AUC-GH, whereas in lean control subjects, the treatment reduced the GHRH-induced response. In normoinsulinemic patients with PCOS, the GH response to the GHRH test increased significantly after treatment, whereas the AUC-I was not affected. In hyperinsulinemic patients with PCOS, treatment with naltrexone significantly reduced the AUC-I, whereas the AUC-GH increased only in lean hyperinsulinemic patients with PCOS.

CONCLUSION(S)

Naltrexone treatment improves GHRH-induced GH secretion in patients with PCOS. However, this GH response is heterogeneously represented in relation to both obesity and hyperinsulinism.

Expression of PEX11beta mediates peroxisome proliferation in the absence of extracellular stimuli

Mammalian cells typically contain hundreds of peroxisomes but can increase peroxisome abundance further in response to extracellular stimuli. We report here the identification and characterization of two novel human peroxisomal membrane proteins, PEX11alpha and PEX11beta. Overexpression of the human PEX11beta gene alone was sufficient to induce peroxisome proliferation, demonstrating that proliferation can occur in the absence of extracellular stimuli and may be mediated by a single gene. Time course studies indicated that PEX11beta induces peroxisome proliferation through a multistep process involving peroxisome elongation and segregation of PEX11beta from other peroxisomal membrane proteins, followed by peroxisome division. Overexpression of PEX11alpha also induced peroxisome proliferation but at a much lower frequency than PEX11beta in our experimental system. The patterns of PEX11alpha and PEX11beta expression were examined in the rat, the animal in which peroxisome proliferation has been examined most extensively. Levels of PEX11beta mRNA were similar in all tissues examined and were unaffected by peroxisome-proliferating agents. Conversely, PEX11alpha mRNA levels varied widely among different tissues, were highest in tissues that are sensitive to peroxisome-proliferating agents, and were induced more than 10-fold in response to the peroxisome proliferators clofibrate and di(2-ethylhexyl) phthalate. Taken together, these data implicate PEX11beta in the constitutive control of peroxisome abundance and suggest that PEX11alpha may regulate peroxisome abundance in response to extracellular stimuli.

Evaluation of pre- and postprandial growth hormone (GH)-releasing hormone-induced GH response in subjects with persistent body weight normalisation after biliopancreatic diversion

BACKGROUND

Obesity is characterised by growth hormone (GH) abnormalities, including a blunted response to stimulation and a 'paradoxical' increase after meals. The blunted GH release is reversed by a surgical intestinal bypass procedure. However, this does not mean that normal GH dynamics have been restored. The present study assessed whether post-surgical weight reduction in obese patients normalised the modulation of GH release produced by metabolic fuels.

SUBJECTS

Ten obese female subjects, aged 23-54 y, were studied before and after biliopancreatic diversion (BPD). All patients, after surgery, had experienced a significant reduction in body weight (mean body mass index (BMI) 25.78 +/- 1.01 kg/m2 vs 44.68 +/- 1.73 kg/m2). Two groups were also studied as controls: Ten normal body weight female subjects and ten patients suffering from anorexia nervosa (AN, mean BMI 17.46 +/- 1.12 kg/m2).

MEASUREMENTS

We have studied the GH response to a GH releasing hormone (GHRH) bolus (1 microg/kg i.v., at 13.00 h) before and after a standard meal.

RESULTS

In post-BPD subjects, the GH response to GHRH in the fasting state, was clearly augmented in comparison with the pre-BPD values (peak values 18.06 +/- 4.56 vs 3.24 +/- 0.68 microg/L). In post-BPD subjects the postprandial GH response was further augmented in comparison with the fasting test (peak 30.12 +/- 4.99 microg/L, P < 0.05). This pattern was similar to that observed in anorexic patients.

CONCLUSION

The surgical procedure restores a normal GH response to GHRH in the fasting state, but the 'paradoxical' GH response after meals remains present, suggesting a persistent GH derangement in such patients, which is not related to body weight per se. The surgical procedure makes obese patients similar to anorexics, in the relationships between metabolic fuels and GH secretion. The persistence of the GH postprandial response to GHRH in post-BPD subjects suggests a role for metabolic fuels in the regulation of somatostatin (SRIF) secretion.

Mammalian orthologs of C. elegans unc-119 highly expressed in photoreceptors

PURPOSE

To characterize orthologous human and murine cDNAs isolated through separate screens designed to identify genes expressed preferentially in retina.

METHODS

By screening bovine, murine, and human retinal cDNA libraries, human UNC-119 clones of two varieties and a murine cDNA clone corresponding to the most abundant human transcript were isolated. Northern blot and reverse transcription-polymerase chain reaction analyses were used to determine tissue distribution of UNC-119 expression; in situ hybridization localized it in retina to photoreceptors. Fluorescence in situ hybridization was used to map the human structural gene, and its intron- exon boundaries were elucidated by polymerase chain reaction amplification and sequencing genomic DNA.

RESULTS

UNC-119 was expressed at high levels in photoreceptors and at low levels elsewhere. The most abundant transcript encoded a protein of 240 amino acids with homology to Caenorhabditis elegans UNC-119. Rat and human cDNAs of UNC-119 have been previously reported as human retinal gene 4 and rat retinal gene 4 (HRG4 and RRG4). An alternative splice form in humans arose from retention of the 3'-most intron, seemed to be retina-specific, and encoded a protein of 220 amino acids. The human structural gene mapped to 17q 1.2 and comprised at least five exons and four introns. A patient with neurofibromatosis type 1, which also maps to 17q11.2, and cone-rod dystrophy was examined for a deletion of UNC-119 but no abnormalities were found.

CONCLUSIONS

Given its strong degree of evolutionary conservation and abundant and nearly exclusive expression in photoreceptors, it is likely that UNC-119 plays an important role in vision and is a strong candidate gene for retinal diseases that map to 17q11.2.

Mutations in the Delta1-pyrroline 5-carboxylate dehydrogenase gene cause type II hyperprolinemia

We surveyed Delta1-pyrroline 5-carboxylate dehydrogenase genes from four patients with hyperprolinemia type II using RT-PCR amplification, genomic PCR amplification and direct sequencing. We found four mutant alleles, two with frameshift mutations [A7fs(-1) and G521fs(+1)] and two with missense mutations (S352L and P16L). To test the functional consequences of three of these, we expressed them in a P5CDh-deficient strain of Saccharomyces cerevisiae . In contrast to wild-type human P5CDh, yeast expressing S352L and G521fs(+1) failed to grow on proline and had no detectable P5CDh activity. The P16L allele, however, produced fully functional P5CDh and subsequent analysis suggests that it is polymorphic in the relevant (Spanish) population. Interestingly, the G521fs(+1) allele segregates in the large Irish Traveller pedigree used to define the HPII phenotype. To our knowledge, this is the first description of the molecular basis for this inborn error.

Gyrate atrophy of the choroid and retina: lymphocyte ornithine-delta-aminotransferase activity in different mutations and carriers

Deficiency of omithine-delta-aminotransferase (OAT) causes gyrate atrophy of the choroid and retina with hyperornithinemia (GA; McKusick 258870), a progressive autosomal recessive chorioretinal degeneration leading to early blindness. As residual enzyme activity may vary in different mutations of the OAT gene and explain individual variations in disease progression, a sensitive HPLC modification of the OAT assay in lymphocytes was developed, based on measurement of the dihydroquinozolinium reaction product. The OAT activities (ranges) of 43 Finnish GA patients with mutations L402P/L402P, R180T/L402P, N89K/ L402P, and L402P/x (x = previously unknown allele), were <1-10, <1-13, <1-17, and <1 pmol x min(-1) mg protein(-1), respectively. The OAT activities (mean+/-SD) of nine L402P/ wild heterozygotes were 70+/-50 (range 33-193), and those of 15 healthy control subjects 184+/-60 (range 85-291) pmol x min(-1) mg protein(-1). This lymphocyte assay is an easy, rapid, and sensitive method for reliable recognition of GA homozygotes. OAT mutations of the Finnish patients show similar residual enzyme activity in the lymphocytes. OAT activities in the L402P heterozygotes and healthy control subjects overlap, suggesting that, for reliable carrier detection, the OAT alleles have to be studied. However, as all OAT mutations are not known, direct measurement of enzyme activity has a role in heterozygote identification and possibly also in prenatal diagnosis of GA.

An isoform of pex5p, the human PTS1 receptor, is required for the import of PTS2 proteins into peroxisomes

Mutations in the peroxisome targeting signal (PTS) 1 receptor gene, PEX5 , are responsible for complementation group (CG) 2 of the peroxisome biogenesis disorders (PBD). Of the two reported patients in this CG, cells from PBD018 (homozygous for the missense mutation N489K) are defective in the import of PTS1 proteins into peroxisomes, as expected. However, cells from PBD005 (homozygous for the nonsense mutation R390ter) are defective in the import of both PTS1 and PTS2 proteins, suggesting that the PTS1 receptor also mediates PTS2-targeted protein import. To investigate this possibility, we characterized PEX5 expression and found that it undergoes alternative splicing, producing two transcripts, one containing (PEX5L) and one lacking (PEX5S) a 111 bp internal exon. Fibroblasts from PBD005 have greatly reduced levels of PEX5 transcript and protein as compared with PBD018. Transfection of PBD005 cells with PEX5S cDNA restores PTS1 but not PTS2 import; transfection with PXR5L cDNA restores both PTS1 and PTS2 protein import. Furthermore, transfection of PBD005 cells with PEX5L cDNAs containing the patient mutations (which are located downstream of the additional exon) restores PTS2 but not PTS1 import. Taken together, these data provide an explanation for the different protein import defects in CG2 patients and show that the long isoform of the Pex5 protein is required for peroxisomal import of PTS2 proteins.

Provocative hypothalamopituitary axis tests in severe head injury: correlations with severity and prognosis

OBJECTIVE

To evaluate the effect of severe head injury on both the secretion of basal pituitary hormones and the response to exogenous synthetic hypothalamic releasing factors administration.

DESIGN

Prospective, clinical study.

SETTING

General intensive care unit in a university teaching hospital, Italy.

PATIENTS

Comatose, head-injured patients (n = 22), all intubated and mechanically ventilated, invasively monitored without previous endocrinologic problems and substitutive therapies.

INTERVENTIONS

Routine neuroemergency procedures; administration of exogenous, synthetic hypothalamic releasing hormones.

MEASUREMENTS AND MAIN RESULTS

Determinations of basal concentrations of growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH), triiodothyronine, and thyroxine were performed daily in the first week and on days 15 and 16 after the trauma. Plasma insulin-like growth factor-I and cortisol were also determined on days 2, 7, and 15. We carried out a thyrotropin-releasing hormone (TRH) test for the evaluation of the PRL, TSH, and GH responses on days 1 and 16 after the trauma and a growth hormone-releasing hormone (GHRH) test for the evaluation of GH and PRL responses on days 2, 7, and 15 after the trauma. Outcome was evaluated at 6 mos with the GOS. Triiodothyronine showed low values, even if in the normal range; thyroxine remained in the normal range. Significant increases in insulin-like growth factor-I concentrations were observed on both days 7 and 15 compared with day 2 (p = .024 and p = .034, respectively). The GH response to GHRH was significantly greater on days 7 and 15 than in the very acute phase (p< .01 comparing days 7 and 15 vs. day 2). We found a higher GH response to GHRH on day 7 in group 1 vs. group 2 (as both peak and area under the curve, p = .018 and p = .015, respectively). No difference in GH response was detected on days 2 and 15. A "paradoxical" response of GH to TRH was observed on the day after the head trauma (basal vs. peak, p = .002) but not on day 16. The GH peak response to TRH was greater on day 1 in those patients with an unfavorable course (group 1 vs. group 2, p < .05). The TSH response to TRH was not significantly correlated to the severity of trauma, but it was significantly (p < .04) higher in group 1 than in group 2. Finally, a "paradoxical" PRL response to GHRH administration was present on day 2 (basal vs. peak, p=.0003), day 7 (basal vs. peak, p = .01), and on day 15 after the trauma (basal vs. peak, p = .04).

CONCLUSIONS

Some of the responses to provocative tests have been identified as "paradoxical" and seem to have a great importance in the definition of prognosis in severe head-injured patients, specifically the GH response to TRH and the PRL response to GHRH that are significantly correlated with outcome.

Restoration of PEX2 peroxisome assembly defects by overexpression of PMP70

The mutant Chinese hamster ovary (CHO) cell line Z78/C has defective peroxisome assembly due to a missense mutation in PEX2, the gene which encodes the 35 kDa peroxisomal integral membrane protein. In humans, PEX2 mutations are responsible for complementation group 10 of the human peroxisome biogenesis disorders (PBD), a genetically heterogeneous group of lethal, autosomal recessive diseases including the Zellweger syndrome and related phenotypes. To develop additional cellular models for Zellweger syndrome, we produced a series of new mutant CHO cell clones in the same complementation group as Z78/C (Z2, Z7, Z22, and Z105). As expected, expression of human PEX2 restores peroxisomal biogenesis in all of these clones. Surprisingly, expression of the human 70 kDa peroxisomal membrane protein (PMP70) also restores peroxisome biogenesis in these same CHO cell clones. We confirmed this effect of PMP70 expression on peroxisome biogenesis by determining the subcellular latency of catalase, the immunohistochemical localization of catalase and the beta-oxidation of very long chain fatty acids (VLCFA). By contrast, expression of a mutant allele of PMP70 identified in a patient with Zellweger syndrome did not restore peroxisome biogenesis in the PEX2-deficient CHO cell clones. Our results indicate that overexpression of PMP70 suppresses the phenotype of PEX2 gene mutations. These observations suggest a functional interaction between PEX2 and PMP70 in the peroxisome membrane.

Identification of PEX10, the gene defective in complementation group 7 of the peroxisome-biogenesis disorders

The peroxisome-biogenesis disorders (PBDs) are a group of genetically heterogeneous, lethal diseases that are characterized by neuronal, hepatic, and renal abnormalities; severe mental retardation; and, in their most severe form, death within the 1st year of life. Cells from all PBD patients exhibit decreased import of one or more classes of peroxisome matrix proteins, a phenotype shared by yeast pex mutants. We identified the human orthologue of yeast PEX10 and observed that its expression rescues peroxisomal matrix-protein import in PBD patients' fibroblasts from complementation group 7 (CG7). In addition, we detected mutations on both copies of PEX10 in two unrelated CG7 patients. A Zellweger syndrome patient, PBD100, was homozygous for a splice donor-site mutation that results in exon skipping and loss of 407 bp from the PEX10 open reading frame. A more mildly affected neonatal adrenoleukodystrophy patient was a compound heterozygote for a missense mutation in the PEX10 zinc-binding domain, H290Q, and for a nonsense mutation, R125ter. Although all three mutations attenuate PEX10 activity, the two alleles detected in the mildly affected patient, PBD052, encode partially functional PEX10 proteins. PEX10-deficient PBD100 cells contain many peroxisomes and import peroxisomal membrane proteins but do not import peroxisomal matrix proteins, indicating that loss of PEX10 has its most pronounced effect on peroxisomal matrix-protein import.

Management of cervical intraepithelial neoplasia of the uterine cervix: 110 cases treated by cold-knife conization

PURPOSE OF INVESTIGATION

The purpose of this study was to evaluate treatment by cold-knife-conization in women carriers of cervical intraepithelial neoplasia (CIN).

METHODS

The histologic findings of pre-clinical neoplasia of the cervix after conization were compared to the previous findings of cytology, colposcopy and punch-biopsy in 110 women examined between 1985 and 1995. The chi square test (chi2) was used for the statistical analysis.

RESULTS AND CONCLUSIONS

A close correlation is clinically important where complementary roles of these three methods are used to identify lesions suitable for local ablative therapy. The Pap test alone is no longer sufficient for the screening of the pre-cancerous lesion of the cervix and colposcopy is compulsory each time the smear is inadequate or altered. Conization permitted us to single out 13 (11.8%) cases of carcinoma. After cold-knife conization we had six (5.4%) recurrences within two years and two (1.8%) within three years. Our data show that conservative therapy by conization in women with CIN reduces the risk of invasive cancer of the cervix but careful follow-up of these patients is essential.

Evaluation of the vascular pattern of hepatocellular carcinoma with dynamic computed tomography and its use in identifying optimal temporal windows for helical computed tomography

The aim of this work was to study the vascularization of hepatocellular carcinoma (HCC) by means of dynamic CT and to demonstrate the existence of optimal temporal windows for visualization of HCC in order to develop new protocols for helical CT of the liver. We studied, by means of dynamic CT, 42 histologically proved HCCs in 30 patients after injecting contrast medium (100 ml, 3 ml/s). We performed a time-density analysis of the aorta, liver, portal vein, spleen and lesion. We identified three temporal curves of attenuation of the neoplastic tissue. Curve 1 was three-phasic: hyperattenuation, isoattenuation and hypoattenuation; curve 2 was two-phasic: hyperattenuation and isoattenuation; curve 3 was two-phasic: isoattenuation and hypoattenuation. Thirty-two lesions were homogeneous (curve 1 in 22 cases, 68.7 %; curve 2 in 7 cases, 21.8 %; curve 3 in 3 cases, 9.4 %), whereas 10 lesions were non-homogeneous. Two optimal temporal windows were identified: the first, with predominantly hyperattenuating lesions (range 29-65 s, 90.4 % sensitivity); the second, with predominantly hypoattenuating lesions (range 132.1-360 s, 76.1 %). There is an interposed time range of reduced visualization (range 62-127 s, 54.7 %) in which lesions are isoattenuating. Combined CT study during the first and second temporal windows improves the detection of HCCs especially for homogeneous and small lesions. The intermediate isoattenuation time range does not increase lesion detection rate.

Identification and characterization of the human ortholog of rat STXBP1, a protein implicated in vesicle trafficking and neurotransmitter release

In a screen designed to identify genes expressed preferentially in retina, we identified a cDNA encoding the human ortholog of rat STXBP1 (n-Sec1, Munc-18-1, rbSec1), a protein implicated in vesicle trafficking and neurotransmitter release. This protein also has similarity to Drosophila Rop (65% aa identity) and Caenorhabditis elegans UNC-18 (58% aa identity). The major human cDNA encodes a protein of 594 amino acids which has 100 % amino acid identity with its rat and murine counterparts. Additionally, there is an alternative splice form in humans, arising from the inclusion of an additional exon, which encodes a protein of 603 amino acids and is also 100% identical to the corresponding rat isoform. We found expression of the shorter cDNA in all tissues and cell lines we examined with highest levels in retina and cerebellum. By RT-PCR analysis, we found expression of the longer cDNA in neural tissues only. We mapped the structural gene to 9q34.1, a region without obvious candidate phenotypes. However, due to its evolutionary conservation and abundant expression in retina and brain, STXBP1 should be considered a candidate gene for retinal and/or neural disorders mapping to 9q34.1.

Molecular analysis of the third component of canine complement (C3) and identification of the mutation responsible for hereditary canine C3 deficiency

Genetically determined deficiency of the third component of complement (C3) in the dog is characterized by a predisposition to recurrent bacterial infections and to type 1 membranoproliferative glomerulonephritis. The current studies were undertaken to characterize the cDNA for wild-type canine C3 and identify the molecular basis for hereditary canine C3 deficiency. Amplification, cloning, and sequence analysis indicated that canine C3 is highly conserved in comparison with human, mouse, and guinea pig C3. Southern blot analysis failed to show any gross deletions or rearrangements of DNA from C3-deficient animals. Northern blot analysis indicated that the livers of these animals contain markedly reduced quantities of a normal length C3 mRNA. The full-length 5.1-kb canine C3 cDNA was amplified in overlapping PCR fragments. Sequence analysis of these fragments has shown a deletion of a cytosine at position 2136 (codon 712), leading to a frameshift that generates a stop codon 11 amino acids downstream. The deletion has been confirmed in genomic DNA, and its inheritance has been demonstrated by allele-specific oligonucleotide hybridization.

Genomic organization of the 70-kDa peroxisomal membrane protein gene (PXMP1)

The 70-kDa peroxisomal membrane protein (PMP70) is a member of a family of half-ATP-binding cassette (ABC) transporter proteins located in the human peroxisomal membrane. Other members include the PMP70-related peroxisomal membrane protein, the adrenoleukodystrophy protein (ALDP), and the adrenoleukodystrophy-related protein. The functions of ABC transporters in the peroxisomal membrane are poorly understood. Evidence from yeast and human mutants suggests that they are involved in the peroxisomal import of fatty acids and/or fatty acyl-CoAs into the organelle. We report the cloning and characterization of the human PMP70 structural gene (gene symbol: PXMP1) localized on human chromosome 1p21-p22. PXMP1 is approximately 65 kb in length, contains 23 exons, and is quite different in structure from the gene (ALD) that encodes the related protein, ALDP. We also analyzed the 5' flanking region of the human PXMP1 gene and the corresponding region of murine Pxmp-1. Both promoters have features of housekeeping genes, including a high GC content and multiple consensus Sp1 binding sequences. In more than 3 kb of Pxmp-1 5' flanking sequence we did not identify a consensus peroxisomal proliferator responsive element.