The time at which ovarian failure (menopause) occurs in females is determined by the size of the oocyte reserve provided at birth, as well as by the rate at which this endowment is depleted throughout post-natal life. Here we show that disruption of the gene for acid sphingomyelinase in female mice suppressed the normal apoptotic deletion of fetal oocytes, leading to neonatal ovarian hyperplasia. Ex vivo, oocytes lacking the gene for acid sphingomyelinase or wild-type oocytes treated with sphingosine-1-phosphate resisted developmental apoptosis and apoptosis induced by anti-cancer therapy, confirming cell autonomy of the death defect. Moreover, radiation-induced oocyte loss in adult wild-type female mice, the event that drives premature ovarian failure and infertility in female cancer patients, was completely prevented by in vivo therapy with sphingosine-1-phosphate. Thus, the sphingomyelin pathway regulates developmental death of oocytes, and sphingosine-1-phosphate provides a new approach to preserve ovarian function in vivo.

No abstract

An inherited deficiency of acid sphingomyelinase (ASM) activity results in the Type A and B forms of Niemann-Pick disease (NPD). Using the ASM-deficient mouse model (ASMKO) of NPD, we evaluated the efficacy of enzyme replacement therapy (ERT) for the treatment of this disorder. Recombinant human ASM (rhASM) was purified from the media of overexpressing Chinese Hamster ovary cells and i.v. injected into 16 five-month-old ASMKO mice at doses of 0.3, 1, 3, or 10 mg/kg every other day for 14 days (7 injections). On day 16, the animals were killed and the tissues were analyzed for their sphingomyelin (SPM) content. Notably, the SPM levels were markedly reduced in the hearts, livers, and spleens of these animals, and to a lesser degree in the lungs. Little or no substrate depletion was found in the kidneys or brains. Based on these results, three additional 5-month-old ASMKO animals were injected every other day with 5 mg/kg for 8 days (4 injections) and killed on day 10 for histological analysis. Consistent with the biochemical results, marked histological improvements were observed in the livers, spleens, and lungs, indicating a reversal of the disease pathology. A group of 10 ASMKO mice were then i.v. injected once a week with 1 mg/kg rhASM for 15 wk, starting at 3 wk of age. Although anti-rhASM antibodies were produced in these mice, the antibodies were not neutralizing and no adverse effects were observed from this treatment. Weight gain and rota-rod performance were slightly improved in the treated animals as compared with ASMKO control animals, but significant neurological deficits were still observed and their life span was not extended by ERT. In contrast with these CNS results, striking histological and biochemical improvements were found in the reticuloendothelial system organs (livers, spleens, and lungs). These studies indicate that ERT should be an effective therapeutic approach for Type B NPD, but is unlikely to prevent the severe neurodegeneration associated with Type A NPD.

Niemann Pick disease is a family of autosomal recessive disorders characterized by cholesterol accumulation. The most common type is Niemann Pick type A/B (NPA/B), resulting from deficient acid sphingomyelinase activity, which leads to sphingomyelin and cholesterol accumulation. The neuropathology of NPA/B includes widespread neuronal degeneration. An acid sphingomyelinase knockout mouse model of NPA/B (ASMKO) has been developed by the targeted deletion of the acid sphingomyelinase gene. When cerebellar morphology was examined in the ASMKO mouse at postnatal day 60 (P60), a dramatic pattern of longitudinal stripes was revealed in which roughly half the Purkinje cells had died, leaving a highly stereotyped, bilaterally symmetrical array of stripes. Antizebrin II immunocytochemistry revealed that the absent Purkinje cells corresponded exactly to the zebrin II-negative subset, leaving the zebrin II-positive subset apparently intact. By P120, some of the zebrin II-positive Purkinje cells had also been eliminated from the posterior vermis and hemispheres. By P180, all Purkinje cells had been lost from the anterior lobe. Finally at P240, almost all Purkinje cells had disappeared to leave a stereotyped distribution in lobules VI, IX-X and the flocculus and paraflocculus. The temporal pattern of Purkinje cell death demonstrates differential susceptibility of morphologically identical cells that appear to be linked to their molecular phenotypes.

Niemann-Pick Disease (NPD) is an autosomal recessive lysosomal storage disorder caused by a deficiency of acid sphingomyelinase (ASM). NPD occurs in two forms, neuronopathic Type A and nonneuronopathic Type B. The incidence of Type A NPD is highest among Ashkenazi Jews. Type B NPD is more common in non-Jews but has been reported in Ashkenazi Jews. Different mutations in ASM are presumed to be responsible for the different NPD phenotypes. Three mutations are predicted to account for > 95% of all Type A NPD chromosomes among Ashkenazi Jews (L302P, R496L, fsP330). Based on limited screens for these mutations among Ashkenazi Jews, a carrier frequency for Type A NPD of 1:90 is reported for this population. Less is known about mutations responsible for Type B NPD, although one mutation (delta R608) has been identified in both Ashkenazi Jews and non-Jews. Screening of the Ashkenazi Jewish population to detect > 95% of NPD carriers can be accomplished with a four-mutation panel that includes L302P, R496L, fsP330, and delta R608, the three predominant Type A mutations and one recurrent Type B mutation.

Types A and B Niemann-Pick disease (NPD) result from the deficient activity of acid sphingomyelinase (ASM). Currently, no treatment is available for either form of NPD. Using the ASM knockout (ASMKO) mouse model, we evaluated the effects of ex vivo hematopoietic stem cell gene therapy on the NPD phenotype. Thirty-two newborn ASMKO mice were preconditioned with low dose radiation (200 cGy) and transplanted with ASMKO bone marrow cells which had been transduced with an ecotropic retroviral vector encoding human ASM. Engraftment of donor-derived cells ranged from 15 to 60% based on Y-chromosome in situ hybridization analysis of peripheral white blood cells, and was achieved in 92% of the transplanted animals. High levels of ASM activity (up to five-fold above normal) were found in the engrafted animals for up to 10 months after transplantation, and their life-span was extended from a mean of 5 to 9 months by the gene therapy procedure. Biochemical and histological analysis of tissues obtained 4-5 months after

These results demonstrated that BMT could alter the pathologic phenotype in ASMKO mice, but that this procedure alone was not sufficient to elicit a complete therapeutic effect.

Hb Köln was identified by DNA analysis in a Brazilian patient. A four-year old Brazilian female, with jaundice since birth, presented an abnormal band, between A2 and S, in hemoglobin electrophoresis on a cellulose acetate membrane, and a band with electrophoretic migration similar to Hb C on agar gel. Thermic instability and isopropanol precipitation tests were positive. Heinz bodies were observed in the patient’s peripheral blood. Sequencing of the three exons of the b globin gene detected a transition from G to A in the first position of codon 98. This alteration does not create or abolish any known restriction site. In this case, confirmation of the mutation was accomplished by allele-specific oligonucleotide hybridization, which is a simple and fast identification method when the clinical data and hematological and electrophoretic patterns are suggestive of Hb Köln.
Hb Köln resulta da substituição do aminoácido valina por metionina na posição 98 da cadeia da hemoglobina. Embora seja a mais freqüente das hemoglobinas instáveis, possui poucas características que permitem distinguíla sem a realização de análise estrutural da molécula. Com o objetivo de desenvolver um procedimento alternativo à análise protéica, este trabalho descreve a identificação da Hb Köln através de análise de DNA. Uma paciente branca, sexo feminino, 4 anos de idade, com icterícia desde o nascimento, foi analisada, apresentando uma banda anômala entre A2 e S em eletroforese em acetato de celulose, e migração eletroforética semelhante a Hb C em gel de agar. Os testes de instabilidade térmica e de precipitação pelo isopropanol foram positivos e foram observados corpúsculos de Heinz no sangue periférico. Os três exons do gene da globina foram seqüenciados e uma transição de G ® A foi identificada na primeira posição do codon 98. Essa alteração não cria ou abole nenhum sítio conhecido de enzima de restrição. Desta forma, a confirmação da mutação foi levada a efeito através de hibridização com oligonucleotídeos aleloespecíficos, o que permitiu o estabelecimento de um método simples e rápido de identificação de novos casos quando os dados clínicos e o padrão hematológico e eletroforético sugerem Hb Köln