A cytotoxic factor for glial cells: a new avenue of research for multiple sclerosis?

A novel retrovirus, provisionally called Multiple Sclerosis RetroVirus (MSRV), was recently described in multiple sclerosis (MS). We report here that monocyte/macrophage culture supernatants from MS patients containing reverse transcriptase activity secrete a cytotoxin which induces death of primary mouse cortical glial cells. This cytotoxin, which was also found in MS cerebrospinal fluid, specifically causes death of mouse immortalized astrocytes and oligodendrocytes in vitro and seems to be associated to MSRV-specific RNA. This toxic factor, called gliotoxin, is present only in active cases of MS and is a stable glycosylated protein of 17 kDa, in CSF as well as in monocyte/macrophage culture supernatants. Since this gliotoxin is highly toxic for glial cells, it may represent an initial pathogenic factor, leading to the neuropathological features of MS, like blood brain barrier disruption and demyelination.

[Angiodysplasia of moya-moya type disclosed by choreic unvoluntary abnormal movements during oral contraception. Apropos of 2 cases]

Two seventeen year-old women, developed acute onset left choreic movements following two months and two weeks use of oral contraceptives. Left hemiparesia appeared a few days later, while involuntary movements discontinued. Cranial CT scan and MRI showed bilateral ischemic lesion in the frontal region for the first case and isolated lesion in the right centrum ovale for the second. Angiography showed nearly complete obstruction of the terminal portion of the internal carotid artery with an outline Moya-Moya network. After discontinuing oral contraceptives, there has been no relapse of neurologic dysfunction for more than three years for the first case and twelve months for the second one. The role of perfusion insufficiency in limb-shaking carotid transient ischemic attack is discussed and the possible relations between oral contraceptives, chorea and angiographic features resembling Moya-Moya disease are evaluated.

Gordona terrae central nervous system infection in an immunocompetent patient

The bacterial genus Gordona includes seven species of mycolic acid-containing actinomycetes which are cultured from environmental sources and rarely from clinical samples. They have been implicated in primary pulmonary diseases, nosocomial wound infections, and central nervous system infections in two immunocompromised patients. We isolated Gordona terrae from the cerebrospinal fluid sample of an immunocompetent patient with meningitis and multiple brain abscesses and detected Gordona terrae DNA in the abscesses. The outcome was good at the 4-year follow-up, after prolonged treatment with trimethoprim-sulfamethoxazole. Phenotypic identification of this isolate was confirmed by analysis of the 16S rRNA gene sequence, which shared 100% homology with that of G. terrae reference strains. Physicians and clinical microbiologists must be aware of the occurrence of Gordona species infection not only among immunocompromised patients but among all patients. Accurate identification of Gordona species may be accomplished by molecular techniques.

The use of oral terbinafine (Lamisil) in children

In an ongoing study of Lamisil in children, 21 patients have so far been enrolled and preliminary data are reported in this paper. Eighteen have tinea capitis and 1 has tinea corporis. So far, Trichophyton tonsurans has been identified in 17 and Trichophyton violaceum in 2. Lamisil has so far proved to be well tolerated, efficacious and cost-effective in a 2-week course in those children with a Trichophyton species. If Microsporum canis is isolated, a longer course is probably indicated. Lamisil has the distinct advantage of producing good results in a short time period, making patient compliance less of a problem.

Germline WT1 mutations in Wilms' tumor patients: preliminary results

We conducted a comparative study of the prevalence of germline WT1 mutations in patients with Wilms' tumor. Patients in Group 1 have familial Wilms' tumor, bilateral disease, associated urogenital anomalies, and/or second cancers. Those in Group 2 are unilateral, sporadic Wilms' patients without other associated conditions. Patients with aniridia or Denys-Drash syndrome are known to have WT1 alterations, and are excluded from this study. Preliminary results on 96 subjects show that the overall germline WT1 mutation frequency is low (< 5%). The work to date establishes the feasibility of identifying patients with germline WT1 mutations and, in the future, offering genetic predisposition testing to at-risk relatives. However, genetic predisposition testing of children for WT1 mutations raises many ethical, legal, and psychosocial issues; research is needed to evaluate risks and benefits.

The renal brush border membrane sodium/sulfate cotransporter functions in situ as a homotetramer

The functional molecular size of the renal Na+/SO4(2-) cotransporter was analysed with the radiation inactivation and fragmentation method. Purified brush border membrane vesicles preserved in a cryoprotective medium were exposed to gamma-radiations. Initial rates of SO4(2-) influx into these vesicles were estimated with membranes irradiated with 0, 4 and 8 Mrad. In each case, SO4(2-) uptake by irradiated membranes was significantly reduced but remained linear during the first 5 sec of incubation. To avoid artifacts arising from a decrease in the driving force caused by modifications in membrane permeability, this incubation period was chosen to measure the effect of irradiation on the SO4(2-) transport activity. Increasing irradiation doses resulted in a monoexponential decrease in transport activity allowing the molecular size to be estimated at 238 +/- 6 kDa (SD, n = 3). Recently, a cDNA for the Na+/SO4(2-) cotransporter was cloned and expressed in Xenopus laevis oocytes (Markovich D. et al. (1993) Proc. Natl Acad. Sci. U.S.A. 90, 8073-8077). The deduced amino acid sequence of this cotransporter predicts a molecular weight of 66 kDa. We suggest that the in situ activity of the renal brush border membrane Na+/SO4(2-) cotransporter requires the presence of four intact and identical subunits arranged as a homotetramer.

Identification of nuclear localization signals within the zinc fingers of the WT1 tumor suppressor gene product

WT1 encodes a zinc finger protein with a key role in urogenital development that is inactivated in a subset of Wilms' tumors. This tumor suppressor gene product contains an amino-terminal dimerization domain required for trans-inhibition of wild-type WT1 activity by mutants defective for DNA binding. In the course of characterizing truncation mutants of WT1, we noted that the WT1 zinc fingers contain two functionally independent targeting signals required for nuclear localization of the protein. These novel signals lie within zinc fingers I and within zinc fingers II and III. We demonstrate that nuclear targeting of the WT1 homodimerization domain functionally antagonizes activity of the wild-type protein activity.

PAX8-mediated activation of the wt1 tumor suppressor gene

The developing renal system has long been exploited to study the regulation of gene expression during mesenchymal-epithelial transitions. Several transcription factors, including WT1 and PAX8, are expressed early in nephrogenesis and play a key role in this process. The expression of PAX8 occurs in the induced mesenchyme of the developing kidney prior to the upregulation of WT1 levels in the same cells. In this report, we assessed whether the Pax-8 gene product resides upstream of wt1 in a common regulatory pathway. Transfection studies, as well as gel-shift assays, indicate that PAX8 transactivates wt1 through elements within a 38 bp conserved motif, present in human and murine promoters. Two PAX8 isoforms, generated by alternative splicing at the C-terminus and previously thought to lack transactivation potential, were found to be capable of activating wt1 expression. We also demonstrate that the endogenous wt1 promoter can be upregulated by exogenously supplied PAX8, suggesting that a function of PAX8 during mesenchymal--epithelial cell transition in renal development is to induce wt1 gene expression.

The sheep estrogen receptor: cloning and regulation of expression in the hypothalamo-pituitary axis

We have prepared an ovine pituitary cDNA library, isolated a clone containing the full-coding sequence of estrogen receptor (ER) cDNA, and determined its primary structure. This cDNA encodes a protein of 596 amino acids which shows great homology to other mammalian ER sequences, the highest degree being 95% with the porcine receptor. Northern blot analysis of ovine pituitary RNA revealed a 6.3 kb transcript. This receptor was showed to bind a consensus ERE and to be transcriptionally activated by E2. Studies investigating the pattern of expression of the ovine ER mRNA were also carried out, using the reverse transcription/PCR technique. Expression of ER mRNA was analyzed in ram pituitary and hypothalamus after contrasted light regimen and castration. Results showed that the light regimen had no effect on ER mRNA expression whereas castration induced a slight (approximately 20%) but significant increase of ER mRNA expression at both the hypothalamic (P < 0.05) and pituitary (P < 0.01) levels, indicating a negative regulation of ER gene expression by testicular steroids. Since we have previously shown no variations in ER protein levels after castration, data suggest the activation of a complex pattern including both transcriptional and post-transcriptional regulatory mechanisms in the ram hypothalamo-pituitary axis.

Evidence for a familial Wilms' tumour gene (FWT1) on chromosome 17q12-q21

Wilms' tumour (WT) is one of the most common solid tumours of childhood, occurring in 1 in 10,000 children and accounting for 8% of childhood cancers. It is believed to result from malignant transformation of abnormally persistent renal stem cells (nephrogenic rests) which retain embryonic differentiation potential. Although WT is usually sporadic, approximately one percent occur in families in which susceptibility appears to be inherited as an autosomal dominant trait with incomplete penetrance. Predisposition to other cancers or to the developmental abnormalities associated with sporadic WT is not usually apparent in WT families. The WT1 gene at 11p13 (ref.2), and additional genes on chromosomes 11p15 (ref. 3) and 16q (ref. 4) have been implicated in the development of WT but are not responsible for familial WT. We have carried out a genome linkage search in a large Canadian family with seven confirmed cases of WT. Our results provide strong evidence for the localisation of a familial WT predisposition gene, FWT1, to an 18-centimorgan (cM) interval on chromosome 17q12-q21.

The paired-box transcription factor, PAX2, positively modulates expression of the Wilms' tumor suppressor gene (WT1)

The Wilms' tumor suppressor gene, wt1, encodes a zinc finger protein which functions as a transcriptional regulator. Expression of the wt1 gene is developmentally regulated and restricted to a small set of tissues which include the fetal urogenital system, mesothelium, and spleen. In the developing kidney, induction of neprohogenesis by the ureter is accompanied by an increase in expression levels of the Pax-2 gene, a developmentally and spatially regulated paired-box member. This is followed by an increase in wt1 expression as mesenchymal cells condense and differentiate. In this report, we demonstrate that PAX2 isoforms are capable of transactivating the wt1 promoter. Deletion mutagenesis of the wt1 promoter identified an element responsible for mediating PAX2 responsiveness, located between nucleotides -33 and -71 relative to the first wt1 transcription start site. Consistent with its identity as a PAX responsive element, multimerization of this mofit upstream of a heterologous minimal promoter enhanced reporter activity when co-transfected with a Pax-2 expression vector. Finally, we demonstrate that PAX2 can stimulate expression of the endogenous wt1 gene. These results suggest that a role for PAX2 during mesenchyme-to-epithelium transition in renal development is to induce wt1 expression.

Characterization of msim, a murine homologue of the Drosophila sim transcription factor

Mutations in the Drosophila single-minded (sim) gene result in loss of precursor cells that give rise to midline cells of the embryonic central nervous system. During the course of an exon-trapping strategy aimed at identifying transcripts that contribute to the etiology and pathophysiology of Down syndrome, we identified a human exon from the Down syndrome critical region showing significant homology to the Drosophila sim gene. Using a cross-hybridization approach, we have isolated a murine homolog of the Drosophila sim gene, which we designated msim. Nucleotide and predicted amino acid sequence analyses of msim cDNA clones indicate that this gene encodes a member of the basic-helix-loop-helix class of transcription factors. The murine and Drosophila proteins share 88% residues within the basic-helix-loop-helix domain, with an overall homology of 92%. In addition, the N-terminal domain of MSIM contains two PAS dimerization motifs also featured in the Drosophila sim gene product, as well as a small number of other transcription factors. Northern blot analysis of adult murine tissues revealed that the msim gene produces a single mRNA species of approximately 4 kb expressed in a small number of tissues, with the highest levels in the kidneys and lower levels present in skeletal muscle, lung, testis, brain, and heart. In situ hybridization experiments demonstrate that msim is also expressed in early fetal development in the central nervous system and in cartilage primordia. The characteristics of the msim gene are consistent with its putative function as a transcriptional regulator.

Epidemiologic study of on-farm management practices associated with prevalence of Mycobacterium paratuberculosis infections in dairy cattle

OBJECTIVE

To use an on-farm recording form to quantity the effect of specific management practices on apparent prevalence of Mycobacterium paratuberculosis in dairy cattle herds.

DESIGN

Epidemiologic survey.

ANIMALS

26 commercial Wisconsin dairy farms.

PROCEDURES

An instrument was developed on the basis of literature review and expert interviews to quantify on-farm management practices associated with increased apparent prevalence of M paratuberculosis. On-farm visits were conducted to assess how specific management practices were conducted. Apparent prevalence of M paratuberculosis infection was measured for all animals > 20 months old on all farms, using a commercial ELISA. Regression analysis was used to identify management variables that were significantly associated with apparent prevalence of M paratuberculosis.

RESULTS

Regression analysis (R2 = 0.90) identified that high scores for environmental conditions, newborn calf care, grower calf care, bred heifer care, and manure handling were significantly associated with M paratuberculosis apparent prevalence in Wisconsin dairy herds.

CLINICAL IMPLICATIONS

Environmental conditions, newborn calf care, grower calf management, bred heifer management, and manure handling factors may serve as a prioritized checklist for instructing owners and managers where to place emphasis in changing management practices to limit M paratuberculosis prevalence. Likewise, the factors identified as having low association with apparent prevalence may be de-emphasized in control programs, allowing dairy managers to focus time and finances on more effective components of an M paratuberculosis control program.

Associations between subclinical paratuberculosis and milk production, milk components, and somatic cell counts in dairy herds

OBJECTIVE

To determine associations between subclinical Mycobacterium paratuberculosis infection and milk production, milk components, and somatic cell counts of dairy cattle.

DESIGN

Cross-sectional epidemiologic survey.

ANIMALS

23 dairy herds in Wisconsin containing 1,653 adult cows were studied. The herds had above average milk production and a history of bovine paratuberculosis in the herd within the previous 12 months.

PROCEDURE

All adult cows in the herds were tested for paratuberculosis by use of an absorbed ELISA. Milk yield, fat, protein, and somatic cell count data were retrieved electronically from Dairy Herd Improvement Association records.

RESULTS

147 ELISA-positive and 1,506 ELISA-negative cows were identified. ELISA-positive cows had a mature-equivalent milk production of 376 kg (829 lb)/lactation less than that for ELISA-negative herdmates. Significant difference was not found in lactation average percent-ages of fat and protein, or somatic cell count linear score. When comparing ELISA-positive and -negative cow's current mature equivalent milk with all previous lactations, significant difference was found only from the immediate-preceding lactation. When this difference was examined by parity group, significant difference was confined to cows in the second lactation.

CLINICAL IMPLICATIONS

Subclinical paratuberculosis infections, as determined by ELISA, are associated with a 4% reduction in milk yield and add to the already substantial costs of clinical M paratuberculosis infection in the dairy industry.

A non-AUG translational initiation event generates novel WT1 isoforms

The Wilms' tumor (WT) suppressor gene, WT1, is mutated in a small set of WTs and is essential for proper development of the urogenital system. The gene has three sites of transcriptional initiation and produces mRNA transcripts containing 5'-untranslated regions of more than 350 nucleotides. The mRNA, through two alternative splicing events, is predicted to direct the synthesis of four protein isoforms with molecular masses of 47-49 kDa. In this report, we identify and characterize novel WT1 protein isoforms having predicted molecular masses of 54-56 kDa. Mutational analysis of the murine wt1 mRNA demonstrates that the novel isoforms are the result of translation initiation at a CUG codon 204 bases upstream of and in frame with the initiator AUG. We show that these isoforms are present in both normal murine tissue and in WTs. Like WT1, the larger isoforms localize to the cell nucleus and are capable of mediating transcriptional repression. Our results indicate that regulation of WT1 gene expression is more complex than previously suspected and have important implications for normal and abnormal urogenital system development.

Abnormal gonadal differentiation in two subjects with ambiguous genitalia, Mullerian structures, and normally developed testes: evidence for a defect in gonadal ridge development

Among a group of patients with abnormal sexual differentiation, we have identified two subjects who had a 46,XY karyotype, ambiguous genitalia, and well-developed Müllerian structures, but normal appearing testes. The presence of ambiguous genitalia and persistent Müllerian structures implied both Leydig cell and Sertoli cell dysfunction, hence, gonadal dysgenesis. However, the normal testicular histology suggested that the underlying abnormality was not a defect in testis determination itself but an abnormality in timing of gonadal ridge and testis development. In one of the two subjects genomic DNA was available. The sequence of the SRY gene was normal. Because rare patients with partial androgen insensitivity may have a similar phenotype, the AR gene was evaluated by denaturing gradient gel electrophoresis (DGGE) and was normal. Some subjects with mutation of the WT1 gene or with deletion of the distal short arm of chromosome 9 may have similar phenotypes. The WT1 gene was studied by single-strand conformation polymorphism (SSCP) analysis and was normal. In addition, there was no loss of heterozygosity of polymorphic markers in distal 9p. The gene for Müllerian inhibiting substance (MIS) was also studied by SSCP and was normal. Although the exact mechanism for the defect in the two subjects is unknown, it may be due to an abnormality in a gene or genes involved in the timing of gonadal ridge development.

Age-related changes in carboxyl methylation of proteins in the kidney

Age-related changes in the carboxyl methylation activities of L-isoaspartyl/D-aspartyl methyltransferase (PIMT) and C-terminal isoprenylcysteine methyltransferase (PPMT), as well as in the methylation levels of their major substrates, were studied in the soluble and brush border membrane (BBM) fractions of kidney cortex isolated from rats aged 3 weeks, and 2, 7 and 12 months. PIMT activity measured with ovalbumin, an exogenous substrate, decreased by 30% in the soluble fraction, while it increased by 37% in BBM of rats older than 2 months. In the soluble fraction, the affinity of PIMT for the universal methyl donor, S-adenosyl-L-methionine, was unaffected, while the apparent maximal velocity measured with ovalbumin was 30% lower in 7-month-old rats than in 3-week-old rats. However, the amount of PIMT measured by Western blotting with anti-PIMT antibodies in the soluble fraction was not affected by age. These results suggest that a reduction in the specific activity of PIMT in the soluble fraction occurs as a function of age. Stimulation of the methylation of total proteins by guanosine 5'-3-O-(thio) triphosphate (GTP gamma S) increased in the soluble fraction of rats older than 2 months, (30%) and decreased in BBM of rats older than 7 months (25%). The PIMT methylation of endogenous substrates of 48 and 61 kDa in the soluble fraction decreased by 40% in rats older than 2 months, but no significant difference was found for substrates in the BBM fraction as a function of age. On the other hand, the PPMT activity was stable from 3 weeks postnatal to adulthood. The C-terminal carboxyl methylation of the major PPMT substrates in BBM (22, 26, and 44 kDa) remained stable throughout development and in adults. The levels of carboxyl methylation of the 22 and 26 kDa substrates in BBM were GTP gamma S-dependent, but only the effect on the 22 kDa substrate was regulated by age. These data suggest that the activities of PIMT and PPMT are regulated differently during development and aging in the rat kidney cortex.

[Reflex epilepsy with seizures induced by mental calculation, playing chess and scrabble]

Reflex seizures induced by higher mental activity is rare. We report the case of a young man with myoclonic jerks and generalized tonico-clonic convulsion precipitated by calculation, playing chess and scrabble. Routine EEG, including hyperventilation and photic stimulation, showed no abnormality. Tests stimulation procedures, including spatial tasks, induced focal and generalized EEG spike-wave complex and myoclonic jerks. Valproate was effective in reducing epileptic seizures during a follow-up period of three years. Comparison of our case with previously reported reflex epilepsy with seizures induced by higher mental activity is discussed.

Antagonism of WT1 activity by protein self-association

Germline loss-of-function mutations at the Wilms tumor (WT) suppressor locus WT1 are associated with a predisposition to WTs and mild genital system anomalies. In contrast, germ-line missense mutations within the WT1 gene encoding the DNA-binding domain often yield a more severe phenotype consisting of WT, sexual ambiguity, and renal nephropathy. In this report, we demonstrate that the products of mutant alleles that impair DNA recognition can antagonize WT1-mediated transcriptional repression. We demonstrate that WT1 can self-associate in vitro and in vivo and that the responsible domain maps to the amino-terminal region of the protein. Oligomers of full-length protein form less efficiently or produce less stable complexes than oligomers between truncated polypeptides and full-length protein. Our data suggest a molecular mechanism to explain how WT1 mutations may act in deregulating cellular proliferation and differentiation.

The human steroidogenic acute regulatory (StAR) gene is expressed in the urogenital system and encodes a mitochondrial polypeptide

The first enzymatic step in the biosynthesis of steroid hormones occurs in the mitochondrial inner membrane and is dependent on the mobilization of cholesterol from cellular stores. We report on the isolation of a human cDNA which encodes a mitochondrial protein called steroidogenic acute regulatory (StAR) protein, implicated in transport of cholesterol into mitochondria. Nucleotide and predicted amino acid sequence analyses indicate that the human and murine polypeptides are highly conserved, sharing 87% identity with an overall homology of 92%. Analysis of the distribution of StAR mRNA transcripts in human tissues by Northern blotting reveals several mRNA species, the most abundant of which is a 1.8 kb mRNA transcript present in testes, ovaries and kidneys. Using in vitro translated protein, we demonstrate that the StAR gene product can be efficiently imported into exogenously added mitochondria.