daf-16: An HNF-3/forkhead family member that can function to double the life-span of Caenorhabditis elegans

The wild-type Caenorhabditis elegans nematode ages rapidly, undergoing development, senescence, and death in less than 3 weeks. In contrast, mutants with reduced activity of the gene daf-2, a homolog of the insulin and insulin-like growth factor receptors, age more slowly than normal and live more than twice as long. These mutants are active and fully fertile and have normal metabolic rates. The life-span extension caused by daf-2 mutations requires the activity of the gene daf-16. daf-16 appears to play a unique role in life-span regulation and encodes a member of the hepatocyte nuclear factor 3 (HNF-3)/forkhead family of transcriptional regulators. In humans, insulin down-regulates the expression of certain genes by antagonizing the activity of HNF-3, raising the possibility that aspects of this regulatory system have been conserved.

Regulation of the Caenorhabditis elegans longevity protein DAF-16 by insulin/IGF-1 and germline signaling

The lifespan of Caenorhabditis elegans is regulated by the insulin/insulin-like growth factor (IGF)-1 receptor homolog DAF-2, which signals through a conserved phosphatidylinositol 3-kinase (PI 3-kinase)/Akt pathway. Mutants in this pathway remain youthful and active much longer than normal animals and can live more than twice as long. This lifespan extension requires DAF-16, a forkhead/winged-helix transcription factor. DAF-16 is thought to be the main target of the DAF-2 pathway. Insulin/IGF-1 signaling is thought to lead to phosphorylation of DAF-16 by AKT activity, which in turn shortens lifespan. Here, we show that the DAF-2 pathway prevents DAF-16 accumulation in nuclei. Disrupting Akt-consensus phosphorylation sites in DAF-16 causes nuclear accumulation in wild-type animals, but, surprisingly, has little effect on lifespan. Thus the DAF-2 pathway must have additional outputs. Lifespan in C. elegans can be extended by perturbing sensory neurons or germ cells. In both cases, lifespan extension requires DAF-16. We find that both sensory neurons and germline activity regulate DAF-16 accumulation in nuclei, but the nuclear localization patterns are different. Together these findings reveal unexpected complexity in the DAF-16-dependent pathways that regulate aging.

Frzb, a secreted protein expressed in the Spemann organizer, binds and inhibits Wnt-8

We isolated a Xenopus homolog of Frzb, a newly described protein containing an amino-terminal Frizzled motif. It dorsalized Xenopus embryos and was expressed in the Spemann organizer during early gastrulation. Unlike Frizzled proteins, endogenous Frzb was soluble. Frzb was secretable and could act across cell boundaries. In several functional assays, Frzb antagonized Xwnt-8, a proposed ventralizing factor with an expression pattern complementary to that of Frzb. Furthermore, Frzb blocked induction of MyoD, an action reported recently for a dominant-negative Xwnt-8. Frzb coimmunoprecipitated with Wnt proteins, providing direct biochemical evidence for Frzb-Wnt interactions. These observations implicate Frzb in axial patterning and support the concept that Frzb binds and inactivates Xwnt-8 during gastrulation, preventing inappropriate ventral signaling in developing dorsal tissues.

Sulindac inhibits activation of the NF-kappaB pathway

Sulindac is a non-steroidal anti-inflammatory agent that is related both structurally and pharmacologically to indomethacin. In addition to its anti-inflammatory properties, sulindac has been demonstrated to have a role in the prevention of colon cancer. Both its growth inhibitory and anti-inflammatory properties are due at least in part to its ability to decrease prostaglandin synthesis by inhibiting the activity of cyclooxygenases. Recently, we demonstrated that both aspirin and sodium salicylate, but not indomethacin, inhibited the activity of an IkappaB kinase beta (IKKbeta) that is required to activate the nuclear factor-kappaB (NF-kappaB) pathway. In this study, we show that sulindac and its metabolites sulindac sulfide and sulindac sulfone can also inhibit the NF-kappaB pathway in both colon cancer and other cell lines. Similar to our previous results with aspirin, this inhibition is due to sulindac-mediated decreases in IKKbeta kinase activity. Concentrations of sulindac that inhibit IKKbeta activity also reduce the proliferation of colon cancer cells. These results suggest that the growth inhibitory and anti-inflammatory properties of sulindac may be regulated in part by inhibition of kinases that regulate the NF-kappaB pathway.

A human chondrodysplasia due to a mutation in a TGF-beta superfamily member

The TGF-beta superfamily comprises a number of functionally diverse growth factors/signalling molecules (1) which elicit their response upon binding to serine-threonine kinase receptors (2). We recently reported the isolation and characterization of two new members of the family, designated cartilage-derived morphogenetic protein (CDMP) 1 and 2 (ref. 3) which are closely related to the sub-family of bone morphogenetic proteins. CDMP-1 is predominantly expressed at sites of skeletal morphogenesis (3), and we now show that a mutation in hCDMP-1 is associated with a recessive human chondrodysplasia (acromesomelic chondrodysplasia, Hunter-Thompson type (4,5)). The disorder, characterized by skeletal abnormalities restricted to the limbs andlimb joints, is phenotypically similar to murine brachypodism (bp) which is due to mutations in growth/differentiation factor-5 (Gdf-5) (6), the mouse homologue of hCDMP-1. Affected individuals are homozygous for a 22-bp (tandem-duplication) frameshift mutation in the mature region of CDMP-1. The resulting phenotype provides direct evidence for the involvement of CDMP-1 in human skeletal development and represents the first human disorder attributable to a mutation in a TGF-beta superfamily member.

Randomised trial of Haemophilus influenzae type-b tetanus protein conjugate vaccine [corrected] for prevention of pneumonia and meningitis in Gambian infants

BACKGROUND

In developing countries, pneumonia and meningitis due to Haemophilus influenzae type b (Hib) are common in children under age 12 months and the mortality from meningitis is high. Protein-polysaccharide conjugate vaccines have brought Hib disease under control in industrialised countries. We did a double-blind randomised trial in The Gambia to assess the efficacy of a Hib conjugate vaccine for the prevention of meningitis, pneumonia, and other invasive diseases due to Hib.

METHODS

Between March, 1993, and October, 1995, 42,848 infants were randomly allocated the conjugate vaccine Hib polysaccharide tetanus protein (PRP-T) mixed with diphtheria-tetanus-pertussis vaccine (DTP), or DTP alone at age 2 months, 3 months, and 4 months. Children who presented with signs of invasive Hib were investigated by blood culture and, where appropriate, by lumbar puncture, chest radiograph, or percutaneous lung aspirate. Children were followed up for between 5 and 36 months.

FINDINGS

The median ages at which children received the study vaccine were 11 weeks, 18 weeks, and 24 weeks. 83% of children enrolled received all three doses of vaccine. 17 cases of culture-positive Hib pneumonia, 28 of Hib meningitis, and five of other forms of invasive Hib disease were detected amongst the study children. The efficacy of the vaccine for the prevention of all invasive disease after three doses was 95% (PRP-T vaccinees 1, controls 19 [95% CI 67-100]), for the prevention of Hib pneumonia after two or three doses, 100% (vaccinees 0, controls 10 [55-100]), and for the prevention of radiologically defined pneumonia at any time after enrollment, 21.1% (PRP-T vaccinees 198, controls 251 [4.6-34.9]).

INTERPRETATION

PRP-T conjugate Hib vaccine prevented most cases of meningitis and pneumonia due to Hib in Gambian infants. The reduction in the overall incidence of radiologically defined pneumonia in PRP-T vaccinees suggests that about 20% of episodes of pneumonia in young Gambian children are due to Hib. The introduction of Hib vaccines into developing countries should substantially reduce childhood mortality due to pneumonia and meningitis.

Metal on metal surface replacement of the hip. Experience of the McMinn prothesis

The historical failure of surface replacement has been due to the production of wear debris with subsequent bone resorption, loosening, and failure. To avoid these problems, a surface replacement using a metal on metal bearing allowing thin components and femoral design and instrumentation to avoid varus alignment has been designed. Two hundred thirty-five joints have been resurfaced with this prosthesis in almost 5 years. There have been no femoral neck fractures and no dislocations. There have been 4 designs differing in the method of fixation. In the press fit group, 6 of 70 hips had to be revised for aseptic loosening. In the cemented group, debonding of the cup occurred in 3 of 43 cases. Six patients had hydroxyapatite coated components and have had excellent clinical outcomes. The current design uses a peripherally expanded hydroxyapatite coated cup and a cemented metal head; 116 of this design have been implanted during a 19-month period with excellent outcome. Despite short followup the authors are hopeful that the combination of a polar metal on metal bearing with appropriate fixation will yield a method of preserving bone stock in the younger patient requiring arthroplasty.

Disruption of human limb morphogenesis by a dominant negative mutation in CDMP1

Chondrodysplasia Grebe type (CGT) is an autosomal recessive disorder characterized by severe limb shortening and dysmorphogenesis. We have identified a causative point mutation in the gene encoding the bone morphogenetic protein (BMP)-like molecule, cartilage-derived morphogenetic protein-1 (CDMP-1). The mutation substitutes a tyrosine for the first of seven highly conserved cysteine residues in the mature active domain of the protein. We demonstrate that the mutation results in a protein that is not secreted and is inactive in vitro. It produces a dominant negative effect by preventing the secretion of other, related BMP family members. We present evidence that this may occur through the formation of heterodimers. The mutation and its proposed mechanism of action provide the first human genetic indication that composite expression patterns of different BMPs dictate limb and digit morphogenesis.

CX3CR1+ interstitial dendritic cells form a contiguous network throughout the entire kidney

Dendritic cells (DCs) interface innate and adaptive immunity in nonlymphoid organs; however, the exact distribution and types of DC within the kidney are not known. We utilized CX3CR1GFP/+ mice to characterize the anatomy and phenotype of tissue-resident CX3CR1+ DCs within normal kidney. Laser-scanning confocal microscopy revealed an extensive, contiguous network of stellate-shaped CX3CR1+ DCs throughout the interstitial and mesangial spaces of the entire kidney. Intravital microscopy of the superficial cortex showed stationary interstitial CX3CR1+ DCs that continually probe the surrounding tissue environment through dendrite extensions. Flow cytometry of renal CX3CR1+ DCs showed significant coexpression of CD11c and F4/80, high major histocompatibility complex class II and FcR expression, and immature costimulatory but competent phagocytic ability indicative of tissue-resident, immature DCs ready to respond to environment cues. Thus, within the renal parenchyma, there exists little immunological privilege from the surveillance provided by renal CX3CR1+ DCs, a major constituent of the heterogeneous mononuclear phagocyte system populating normal kidney.

Mental health issues for Asian Americans

One of fastest-growing population groups in recent decades, Asian Americans represent a vastly diversified and rich mixture of cultures, languages, beliefs, and practices, many of which differ widely from those of European Americans. As immigrants, Asian Americans have experienced and continue to experience various emotional and behavioral problems. However, they tend to underuse existing services except those that are culturally appropriate and linguistically compatible. Misdiagnosis frequently occurs, and the existence of culture-bound syndromes points to a lack of precise correspondence between indigenous labels and established diagnostic categories. Due to Asian traditions of viewing the body and mind as unitary rather than dualistic, patients tend to focus more on physical discomforts than emotional symptoms, leading to an overrepresentation of somatic complaints. Traditional practices and healing methods are frequently used to alleviate distress both before and after patients and their family members approach the conventional mental health care system. Help seeking typically is a family venture. Asian patients respond well to highly structured therapeutic interventions such as those used in behavioral, cognitive, and interpersonal models. When applying pharmacotherapy, clinicians should pay attention to Asians' unique responses to psychotropics, especially in regard to dosage requirements and side effects. Research in this area as well as on other important issues is in the early stage of development.

Molecular mechanism of endothelial growth arrest by laminar shear stress

This study was designed to elucidate the mechanism underlying the inhibition of endothelial cell growth by laminar shear stress. Tumor suppressor gene p53 was increased in bovine aortic endothelial cells subjected to 24 h of laminar shear stress at 3 dynes (1 dyne = 10 microN)/cm(2) or higher, but not at 1.5 dynes/cm(2). One of the mechanisms of the shear-induced increase in p53 is its stabilization after phosphorylation by c-Jun N-terminal kinase. To investigate the consequence of the shear-induced p53 response, we found that prolonged laminar shear stress caused increases of the growth arrest proteins GADD45 (growth arrest and DNA damage inducible protein 45) and p21(cip1), as well as a decrease in phosphorylation of the retinoblastoma gene product. Our results suggest that prolonged laminar shear stress causes a sustained p53 activation, which induces the up-regulation of GADD45 and p21(cip1). The resulting inhibition of cyclin-dependent kinase and hypophosphorylation of retinoblastoma protein lead to endothelial cell cycle arrest. This inhibition of endothelial cell proliferation by laminar shear stress may serve an important homeostatic function by preventing atherogenesis in the straight part of the arterial tree that is constantly subjected to high levels of laminar shearing.

The cysteine-rich frizzled domain of Frzb-1 is required and sufficient for modulation of Wnt signaling

Convincing evidence has accumulated to identify the Frizzled proteins as receptors for the Wnt growth factors. In parallel, a number of secreted frizzled-like proteins with a conserved N-terminal frizzled motif have been identified. One of these proteins, Frzb-1, binds Wnt-1 and Xwnt-8 proteins and antagonizes Xwnt-8 signaling in Xenopus embryos. Here we report that Frzb-1 blocks Wnt-1 induced cytosolic accumulation of beta-catenin, a key component of the Wnt signaling pathway, in human embryonic kidney cells. Structure/function analysis reveals that complete removal of the frizzled domain of Frzb-1 abolishes the Wnt-1/Frzb-1 protein interaction and the inhibition of Wnt-1 mediated axis duplication in Xenopus embryos. In contrast, removal of the C-terminal portion of the molecule preserves both Frzb-Wnt binding and functional inhibition of Wnt signaling. Partial deletions of the Frzb-1 cysteine-rich domain maintain Wnt-1 interaction, but functional inhibition is lost. Taken together, these findings support the conclusion that the frizzled domain is necessary and sufficient for both activities. Interestingly, Frzb-1 does not block Wnt-5A signaling in a Xenopus functional assay, even though Wnt-5A coimmunoprecipitates with Frzb-1, suggesting that coimmunoprecipitation does not necessarily imply inhibition of Wnt function.

Combined and individual mitochondrial HSP60 and HSP10 expression in cardiac myocytes protects mitochondrial function and prevents apoptotic cell deaths induced by simulated ischemia-reoxygenation

BACKGROUND

The mitochondrial heat-shock proteins HSP60 and HSP10 form a mitochondrial chaperonin complex, and previous studies have shown that their increased expression exerts a protective effect against ischemic injury when cardiac myocytes are submitted to simulated ischemia. The more detailed mechanisms by which such a protective effect occurs are currently unclear. We wanted to determine whether HSP60 and HSP10 could exert a protection against simulated ischemia and reoxygenation (SI/RO)-induced apoptotic cell death and whether such protection results from decreased mitochondrial cytochrome c release and caspase-3 activation and from the preservation of ATP levels by preservation of the electron transport chain complexes. In addition, we explored whether increased expression of HSP60 or HSP10 by itself exerts a protective effect.

METHODS AND RESULTS

We overexpressed HSP60 and HSP10 together or separately in rat neonatal cardiac myocytes using an adenoviral vector and then subjected the myocytes to SI/RO. Cell death and apoptosis in myocytes were quantified by parameters such as enzyme release, DNA fragmentation, and caspase-3 activation. Overexpression of the combination of HSP60 and HSP10 and of HSP60 or HSP10 individually protected myocytes against apoptosis. This protection is accompanied by decreases in mitochondrial cytochrome c release and in caspase-3 activity and increases in ATP recovery and activities of complex III and IV in mitochondria after SI/RO.

CONCLUSIONS

These results suggest that mitochondrial chaperonins HSP60 and HSP10 in combination or individually play an important role in maintaining mitochondrial integrity and capacity for ATP generation, which are the crucial factors in determining survival of cardiac myocytes undergoing ischemia/reperfusion injury.

Lifetime and twelve-month prevalence rates of major depressive episodes and dysthymia among Chinese Americans in Los Angeles

OBJECTIVE

The authors' goal was to estimate the lifetime and 12-month rates of major depressive episodes and dysthymia for Chinese Americans who reside in Los Angeles. This effort, the Chinese American Psychiatric Epidemiological Study, is the first large-scale community psychiatric epidemiological study on an Asian American ethnic group that used DSM-III-R criteria for major depressive episodes and dysthymia.

METHOD

A multi-stage sampling design was used to select respondents for participation in the survey. The sample included 1,747 adults, 18-65 years of age, who resided in Los Angeles County and who spoke English, Mandarin, or Cantonese.

RESULTS

Approximately 6.9% of the respondents had experienced an episode of major depression and 5.2% had had dysthymia in their lifetime. The 12-month rates of depressive episode and dysthymia were 3.4% and 0.9%, respectively. The most consistent correlate of lifetime and 12-month depressive episode and dysthymia was social stress, measured by past traumatic events and recent negative life events.

CONCLUSIONS

The Chinese American Psychiatric Epidemiological Study provides a rare opportunity to investigate the heterogeneity within a single Asian American ethnic group, Chinese Americans, and to identify the subgroups among Chinese Americans who may be most at risk for mental health problems.

Clusterin regulates β-amyloid toxicity via Dickkopf-1-driven induction of the wnt-PCP-JNK pathway

Although the mechanism of Aβ action in the pathogenesis of Alzheimer's disease (AD) has remained elusive, it is known to increase the expression of the antagonist of canonical wnt signalling, Dickkopf-1 (Dkk1), whereas the silencing of Dkk1 blocks Aβ neurotoxicity. We asked if clusterin, known to be regulated by wnt, is part of an Aβ/Dkk1 neurotoxic pathway. Knockdown of clusterin in primary neurons reduced Aβ toxicity and DKK1 upregulation and, conversely, Aβ increased intracellular clusterin and decreased clusterin protein secretion, resulting in the p53-dependent induction of DKK1. To further elucidate how the clusterin-dependent induction of Dkk1 by Aβ mediates neurotoxicity, we measured the effects of Aβ and Dkk1 protein on whole-genome expression in primary neurons, finding a common pathway suggestive of activation of wnt-planar cell polarity (PCP)-c-Jun N-terminal kinase (JNK) signalling leading to the induction of genes including EGR1 (early growth response-1), NAB2 (Ngfi-A-binding protein-2) and KLF10 (Krüppel-like factor-10) that, when individually silenced, protected against Aβ neurotoxicity and/or tau phosphorylation. Neuronal overexpression of Dkk1 in transgenic mice mimicked this Aβ-induced pathway and resulted in age-dependent increases in tau phosphorylation in hippocampus and cognitive impairment. Furthermore, we show that this Dkk1/wnt-PCP-JNK pathway is active in an Aβ-based mouse model of AD and in AD brain, but not in a tau-based mouse model or in frontotemporal dementia brain. Thus, we have identified a pathway whereby Aβ induces a clusterin/p53/Dkk1/wnt-PCP-JNK pathway, which drives the upregulation of several genes that mediate the development of AD-like neuropathologies, thereby providing new mechanistic insights into the action of Aβ in neurodegenerative diseases.

The place of culture in DSM-IV

This paper critically reviews the process and outcome of an effort to enhance the cultural validity of DSM-IV and outlines recommendations to improve future diagnostic systems. An ordered presentation of the antecedents and the main phases of this developmental effort is followed by a content analysis of what was proposed and what was actually incorporated, and a conceptual analysis of underlying biases and their implications. The cultural effort for DSM-IV, spearheaded by a scholarly independent NIMH workgroup, resulted in significant innovations including an introductory cultural statement, cultural considerations for the use of diagnostic categories and criteria, a glossary of culture-bound syndromes and idioms of distress, and an outline for a cultural formulation. However, proposals that challenged universalistic nosological assumptions and argued for the contextualization of illness, diagnosis, and care were minimally incorporated and marginally placed. Although a step forward has been taken to introduce cultural elements in DSM-IV much remains to be done. Further culturally informed research is needed to ensure that future diagnostic systems incorporate a genuinely comprehensive framework, responsive to the complexity of health problems in increasingly multicultural societies.

Adaptational problems of Vietnamese refugees. I. Health and mental health status

The forced migratory influx of Vietnamese to the United States has raised questions regarding the resettlement process, the effect of culture shock, the refugees' coping behavior and adaptabilities, and their health and mental health status. We report the two-year results of ongoing research on the Vietnamese refugees based on the use of the Cornell Medical Index (CMI). The responses on the CMI on the first (1975) and second (1976) administrations indicate a high and continuing level of physical and mental dysfunction. The second administration also revealed significant shifts in dysfunctions as well as exposing factors that related to these dysfunctions, ie, age/sex interactions, marital status, family groupings, and public assistance. The follow-up CMI also showed an increase in anger and hostility with concomitant reductions in feelings of inadequacy.

A conformation-specific monoclonal antibody reacting with fusion-active gp41 from the human immunodeficiency virus type 1 envelope glycoprotein

The gp41 subunit of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein plays a major role in the membrane fusion step of viral infection. The ectodomain of gp41 contains a six-helix structural domain that likely represents the core of the fusion-active conformation of the molecule. A monoclonal antibody (MAb), designated NC-1, was generated and cloned from a mouse immunized with the model polypeptide N36(L6)C34, which folds into a stable six-helix bundle. NC-1 binds specifically to both the alpha-helical core domain and the oligomeric forms of gp41. This conformation-dependent reactivity is dramatically reduced by point mutations within the N-terminal coiled-coil region of gp41 which impede formation of the gp41 core. NC-1 binds to the surfaces of HIV-1-infected cells only in the presence of soluble CD4. These results indicate that NC-1 is capable of reacting with fusion-active gp41 in a conformation-specific manner and can be used as a valuable biological reagent for studying the receptor-induced conformational changes in gp41 required for membrane fusion and HIV-1 infection.

Characterization of adipose tissue-derived cells isolated with the Celution system

BACKGROUND

The therapeutic potential of using stem cells is tremendous. Mesenchymal stromal cells (MSC) have now been isolated in various tissues including bone marrow (BM), muscle, skin and adipose tissue. Among them, adipose tissue could be one of the most suitable cell sources for cell therapy, because of its easy accessibility, minimal morbidity and abundance of stem cells. The large numbers of stem cells in adipose tissue means that clinically relevant stem cell numbers could be extracted from the tissue, potentially eliminating the need for in vitro expansion. To utilize these characteristics of adipose tissue fully, Cytori Therapeutics Inc. has developed a closed system called Celution to isolate and concentrate stem cells and regenerative cells automatically from adipose tissue.

METHODS

Adipose tissue-derived cells were isolated using the Celution system. The output from the Celution was characterized using multicolor FACS analysis with CD31, CD34, CD45, CD90, CD105 and CD146. The multidifferentiation potential of the cells was analyzed using adipogenic and osteogenic media.

RESULTS

Our results showed that cells from the Celution are composed of heterogeneous cell populations including adipose-derived stem cells (ASC) (CD31- CD34+ CD45- CD90+ CD105- CD146-), endothelial (progenitor) cells (CD31+ CD34+ CD45- CD90+ CD105- CD146+) and vascular smooth muscle cells (CD31- CD34+ CD45- CD90+ CD105- CD146+). We also confirmed the output contains cells able to differentiate into adipogenic and osteogenic phenotypes. Our results show that cells isolated with the Celution and manually are equivalent.

DISCUSSION

Cells from adipose tissue can be processed by Celution within the time frame of a single surgical procedure. This system could provide a 'real-time' treatment setting that is cost-effective and safe.

An experimental protocol for fertility preservation in prepubertal boys recently diagnosed with cancer: a report of acceptability and safety

BACKGROUND

Gonadal damage is a consequence of therapy for pediatric malignancies. Prepubertal males have no semen or mature spermatozoa, posing a challenge for fertility preservation. Testicular tissue cryopreservation is a potential option but is still experimental. We report on a pilot protocol that offered testicular biopsy cryopreservation to families of prepubertal boys with newly diagnosed malignancy. The aims were to determine the acceptability and safety of this procedure.

METHODS

Parents of prepubertal boys with diagnoses at highest risk for treatment-related gonadal damage were offered the option of testicular cryopreservation. Half of the biopsy was frozen for the subject's potential future use and the remainder used for research. Data on negative intraoperative and/or 7 day post-operative sequelae of testicular biopsies were assessed. Two to four weeks later, parents were asked to complete a questionnaire on factors influencing their decision to have the biopsy or not.

RESULTS

Since January 2008, 24 boys have met the eligibility criteria but three required immediate treatment and were excluded. Sixteen of 21 families (76%) consented to testicular biopsy, indicating the prospective acceptability of this option to parents of boys aged 3 months to 14 years; 14 underwent the procedure without any negative intra- or post-operative sequelae. Although the time at diagnosis is stressful, families can give thoughtful consideration to this option. Factors such as religion, finance, ethics and the experimental nature of cryopreservation did not play a major role in decision-making.

CONCLUSIONS

Parents of prepubertal boys with cancer are willing to pursue testicular tissue cryopreservation at diagnosis, and testicular biopsy caused no acute adverse effects.

The gene encoding hydroxypyruvate reductase (GRHPR) is mutated in patients with primary hyperoxaluria type II

Primary hyperoxaluria type II (PH2) is a rare monogenic disorder that is characterized by a lack of the enzyme that catalyzes the reduction of hydroxypyruvate to D-glycerate, the reduction of glyoxylate to glycolate and the oxidation of D-glycerate to hydroxypyruvate. The disease is characterized by an elevated urinary excretion of oxalate and L-glycerate. The increased oxalate excretion can cause nephrolithiasis and nephrocalci-nosis and can, in some cases, result in renal failure and systemic oxalate deposition. We identified a glyoxylate reductase/hydroxypyruvate reductase (GRHPR) cDNA clone from a human liver expressed sequence tag (EST) library. Nucleotide sequence analysis identified a 1198 nucleotide clone that encoded a 984 nucleotide open reading frame. The open reading frame encodes a predicted 328 amino acid protein with a mass of 35 563 Da. Transient transfection of the cDNA clone into COS cells verified that it encoded an enzyme with hydroxy-pyruvate reductase, glyoxylate reductase and D-glycerate dehydrogenase enzymatic activities. Database analysis of human ESTs reveals widespread tissue expression, indicating that the enzyme may have a previously unrecognized role in metabolism. The genomic structure of the human GRHPR gene was determined and contains nine exons and eight introns and spans approximately 9 kb pericentromeric on chromosome 9. Four PH2 patients representing two pairs of siblings from two unrelated families were analyzed for mutations in GRHPR by single strand conformation polymorphism analysis. All four patients were homozygous for a single nucleotide deletion at codon 35 in exon 2, resulting in a premature stop codon at codon 45. The cDNA that we have identified represents the first characterization of an animal GRHPR sequence. The data we present will facilitate future genetic testing to confirm the clinical diagnosis of PH2. These data will also facilitate heterozygote testing and prenatal testing in families affected with PH2 to aid in genetic counseling.

Clathrin self-assembly is mediated by a tandemly repeated superhelix

Clathrin is a triskelion-shaped cytoplasmic protein that polymerizes into a polyhedral lattice on intracellular membranes to form protein-coated membrane vesicles. Lattice formation induces the sorting of membrane proteins during endocytosis and organelle biogenesis by interacting with membrane-associated adaptor molecules. The clathrin triskelion is a trimer of heavy-chain subunits (1,675 residues), each binding a single light-chain subunit, in the hub domain (residues 1,074-1,675). Light chains negatively modulate polymerization so that intracellular clathrin assembly is adaptor-dependent. Here we report the atomic structure, to 2.6 A resolution, of hub residues 1,210-1,516 involved in mediating spontaneous clathrin heavy-chain polymerization and light-chain association. The hub fragment folds into an elongated coil of alpha-helices, and alignment analyses reveal a 145-residue motif that is repeated seven times along the filamentous leg and appears in other proteins involved in vacuolar protein sorting. The resulting model provides a three-dimensional framework for understanding clathrin heavy-chain self-assembly, light-chain binding and trimerization.