P–459 Ex vivo perfusion of whole ewe ovaries with follicular maturation for up to seven days: towards the development of an alternative fertility preservation method

Study question

To develop an alternative fertility preservation method for young female cancer patients based on an ex vivo perfusion of whole ovaries serving as a platform for future ovarian stimulation studies.

Summary answer

It is possible to maintain viable follicles and to retrieve oocytes after ex vivo perfusion of ewe ovaries for up to 7 days.

What is known already

Some progress has been made in terms of follicular growth and the isolation of mature oocytes in vitro. However, full development, from early follicular stages to a viable offspring, has only been described in rodent models. The complex events controlling follicular expansion and the long time required for folliculogenesis and oocyte maturity in large mammalian species creating challenges and limitations for in vitro studies. Ex vivo perfusion of a whole ovary could potentially be a solution by exploiting the intact ovarian architecture to support folliculogenesis and oocyte maturation.

Study design, size, duration

Thirty-one ewe ovaries were divided into 4 groups and ex vivo perfused in a bioreactor. Group 1 (n = 14) perfusion for 48 hours with no hormone supplementation; Group 2 (n = 4) perfusion 96–101 hours with follicle stimulating hormone (FSH); Group 3 (n = 3) perfusion 120–168 hours with human menopausal gonadotropin (hMG); Group 4 (n = 10) perfusion 72–144 hours with hMG.

Participants/materials, setting, methods

Ewe ovaries from sexually mature ewes were ex vivo perfused in a bioreactor under normothermic conditions for up to 7 days (max total 168 hours). Histomorphological, immunohistochemical, hormonal and biochemical analyses were performed to assess ovarian structure and viability after cold ischemia and after perfusion which was subsequently compared to control ovaries.

Main results and the role of chance

The perfused ovaries in group 2 and 3 showed no significant differences in follicular density, viability and oocyte quality after ischemia and perfusion compared to control ovaries. Estradiol and progesterone levels did not increase during the perfusion. The perfused ovaries in group 1 and 4 showed a significant decrease in the ovarian reserve and oocyte quality. In total, 16 GV-MI oocytes were retrieved from groups 3 and 4.

Limitations, reasons for caution

1. Ovaries were retrieved from ewes of unknown cycle and reproductive history. 2. The perfusion medium was changed after 24 hours from perfusion start to remove detrimental metabolites and this could affect the measured concentrations of hormones and metabolites in the perfusion medium.

Wider implications of the findings: These results pave the way to propose ex vivo perfusion as a good platform for fertility preservation studies on whole mammalian and human ovaries to retrieve fully mature oocytes.

Trial registration number

Not applicable

A Novel Three-Dimensional-Printed Ultrasound-Guided Hip Arthrocentesis Model

When evaluating patients with hip pain, clinicians may be trained to both evaluate for a hip effusion and perform ultrasound-guided arthrocentesis to evaluate the etiology of the effusion. We present a novel 3-dimensional-printed hip arthrocentesis model, which can be used to train clinicians to perform both tasks under ultrasound guidance. Our model uses a combination of a 3-dimensional-printed hip joint, as well as readily available materials such as an infant Ambu (Ballerup, Denmark) bag, syringe, intravenous line kit, and silicone. We present our experience so that others may use and adapt our model for their training purposes.

Effect of multi-nutrient insufficiency on markers of one carbon metabolism in young women: response to a methionine load

BACKGROUND/OBJECTIVES

Multi-nutrient insufficiencies as a consequence of nutritional and economic factors are common in India and other developing countries. We have examined the impact of multi-nutrient insufficiency on markers of one carbon (1C) metabolism in the blood, and response to a methionine load in clinically healthy young women.

SUBJECTS/METHODS

Young women from Pune, India (n=10) and Cleveland, USA (n=13) were studied. Blood samples were obtained in the basal state and following an oral methionine load (50 mg/kg of body weight in orange juice). Plasma concentrations of vitamin B12, folate and B6 were measured in the basal state. The effect of methionine load on the levels of methionine, total homocysteine, cysteine, glutathione and amino acids was examined.

RESULTS

Indian women were significantly shorter and lighter compared with the American women and had lower plasma concentration of vitamins B12, folate and B6, essential amino acids and glutathione, but higher concentration of total homocysteine. The homocysteine response to methionine load was higher in Indian women. The plasma concentrations of glycine and serine increased in the Indian women after methionine (in juice) load. A significant negative correlation between plasma B6 and homocysteine (r= -0.70), and plasma folate and glycine and serine levels were observed in the Indian group (P<0.05) but not in the American group.

CONCLUSIONS

Multi-nutrient insufficiency in the Indian women caused unique changes in markers of whole body protein and 1C metabolism. These data would be useful in developing nutrient intervention strategies.

Mature neurons: equipped for survival

Neurons completely transform how they regulate cell death over the course of their lifetimes. Developing neurons freely activate cell death pathways to fine-tune the number of neurons that are needed during the precise formation of neural networks. However, the regulatory balance between life and death shifts as neurons mature beyond early development. Mature neurons promote survival at all costs by employing multiple, often redundant, strategies to prevent cell death by apoptosis. This dramatic shift from permitting cell death to ensuring cellular survival is critical, as these post-mitotic cells must provide neuronal circuitry for an organism's entire lifetime. Importantly, as many neurodegenerative diseases afflict adult neuronal populations, the survival mechanisms in mature neurons are likely to be either reversed or circumvented during neurodegeneration. Examining the adaptations for inhibiting apoptosis during neuronal maturation is key to comprehending not just how neurons survive long term, but may also provide insight for understanding how neuronal toxicity in various neurodegenerative diseases may ultimately lead to cell death.

Toxicodynamics of rigid polystyrene microparticles on pulmonary gas exchange in mice: implications for microemboli-based drug delivery systems

The toxicodynamic relationship between the number and size of pulmonary microemboli resulting from uniformly sized, rigid polystyrene microparticles (MPs) administered intravenously and their potential effects on pulmonary gas exchange were investigated. CD-1 male mice (6-8 weeks) were intravenously administered 10, 25 and 45 μm diameter MPs. Oxygen hemoglobin saturation in the blood (SpO(2)) was measured non-invasively using a pulse oximeter while varying inhaled oxygen concentration (F(I)O(2)). The resulting data were fit to a physiologically based non-linear mathematical model that estimates 2 parameters: ventilation-perfusion ratio (V(A)/Q) and shunt (percentage of deoxygenated blood returning to systemic circulation). The number of MPs administered prior to a statistically significant reduction in normalized V(A)/Q was dependent on particle size. MP doses that resulted in a significant reduction in normalized V(A)/Q one day post-treatment were 4000, 40,000 and 550,000 MPs/g for 45, 25 and 10 μm MPs, respectively. The model estimated V(A)/Q and shunt returned to baseline levels 7 days post-treatment. Measuring SpO(2) alone was not sufficient to observe changes in gas exchange; however, when combined with model-derived V(A)/Q and shunt early reversible toxicity from pulmonary microemboli was detected suggesting that the model and physical measurements are both required for assessing toxicity. Moreover, it appears that the MP load required to alter gas exchange in a mouse prior to lethality is significantly higher than the anticipated required MP dose for effective drug delivery. Overall, the current results indicate that the microemboli-based approach for targeted pulmonary drug delivery is potentially safe and should be further explored.

Can inhA mutation predict ethionamide resistance?

SETTING

A tertiary care centre in Mumbai, India.

OBJECTIVE

To estimate the extent of association between inhA mutant isoniazid (INH) resistant strains and ethionamide (ETH) resistance.

DESIGN

A total of 140 clinical isolates processed for INH and ETH phenotypic drug susceptibility testing, and molecularly processed with the line-probe assay (LPA) Genotype® MTBDRplus, were considered.

RESULTS

Among the 112 phenotypically determined INH-resistant strains, 69 (61.6%) strains were ETH-resistant. An inhA promoter mutation was identified in 24 (21.4%) INH-resistant isolates, 21 (87.5%) of which were ETH-resistant (P < 0.0001).

CONCLUSION

An inhA promoter mutation could be considered as a marker for the determination of ETH resistance in India, where the use of LPA is being expanded.

Immunophenotype of neoplastic plasma cells in AL amyloidosis

AIM

AL amyloidosis (ALA) is a form of plasma cell (PC) dyscrasia characterised by deposition of insoluble fibrillar deposits in various organs causing organ damage. This is believed to be the first study to evaluate the expression of CD79a, CD20, CD56, cyclin D1 and epithelial membrane antigen (EMA) in neoplastic PCs of ALA.

METHODS AND RESULTS

The study included 36 well-documented cases of ALA. In all cases presence of amyloid deposits had been documented by Congo Red stain in the bone marrow trephine biopsy (BMTB) and/or in other tissues. BMTBs showed varying degrees of PC infiltration (median 12%). In eight of the 36 cases with associated myeloma, the mean (2 x SE) percentage of PCs (PC%) was 34 (18)%, while in the remaining, PC% was 15 (4)%. Expression of CD20, CD79a, CD56, cyclin D1 and EMA was noted in 42%, 86%, 50%, 53% and 83% of cases, respectively. Aberrant antigen expression in the form of CD56 and/or cyclin D1 expression was seen in 79% of cases. Nine of 10 cases with small lymphoid-like PCs were positive for CD20 and all the 10 cases were positive for cyclin D1. On the other hand, among cases without small lymphoid-like morphology, CD20 and cyclin D1 expression was seen in only 6 of 26 and 8 of 26 cases respectively (p = 0.001 and 0.002 respectively). CD20 expression correlated with cyclin D1 expression (p = 0.045). Cytological atypia/pleomorphism was predictive of associated myeloma (p = <0.001).

CONCLUSION

Marrow involvement by neoplastic PCs in ALA can be identified by their aberrant antigen expression apart from light chain restriction, and rituximab as a possible treatment option may be explored in CD20-positive ALA.

MRI imaging of ulnar leprosy abscess

Leprosy is a chronic granulomatous infection, caused by mycobacterium leprae, primarily affecting the peripheral nerve trunks and cutaneous nerves. It classically presents with neural or dermal signs and symptoms. The indolent course of leprosy may manifest as erythema nodosum (appearance of tender inflamed subcutaneous nodule) and reversal reaction (inflammation in the previous skin lesion, appearance of new skin lesions, neuritis and abscess). Ulnar nerve is most commonly involved. This report illustrates the MR imaging appearance of ulnar nerve abscess.

Endoplasmic reticulum stress-induced apoptosis requires bax for commitment and Apaf-1 for execution in primary neurons

Apoptosis triggered by endoplasmic reticulum (ER) stress is associated with various pathophysiological conditions including neurodegenerative diseases and ischemia. However, the mechanism by which ER stress induces neuronal apoptosis remains controversial. Here we identify the pathway of apoptosis carried out in sympathetic neurons triggered to die by ER stress-inducing agent tunicamycin. We find that ER stress induces a neuronal apoptotic pathway which upregulates BH3-only genes DP5 and Puma. Importantly, we show that ER stress commits neurons to die before cytochrome c release and this commitment requires Bax activation and c-jun N-terminal kinase signaling. Furthermore, ER stress engages the mitochondrial pathway of death as neurons release cytochrome c and Apaf-1 deficiency is sufficient to block apoptosis. Our findings identify a critical function of Bax in committing neurons to ER stress-induced apoptosis and clarify the importance of the apoptosome as the non-redundant caspase activation pathway to execute neuronal apoptosis in response to ER stress.

Essential postmitochondrial function of p53 uncovered in DNA damage-induced apoptosis in neurons

In postmitotic sympathetic neurons, unlike most mitotic cells, death by apoptosis requires not only the release of cytochrome c from the mitochondria, but also an additional step to relieve X-linked inhibitor of apoptosis protein (XIAP)'s inhibition of caspases. Here, we examined the mechanism by which XIAP is inactivated following DNA damage and found that it is achieved by a mechanism completely different from that following apoptosis by nerve growth factor (NGF) deprivation. NGF deprivation relieves XIAP by selectively degrading it, whereas DNA damage overcomes XIAP via a p53-mediated induction of Apaf-1. Unlike wild-type neurons, p53-deficient neurons fail to overcome XIAP and remain resistant to cytochrome c after DNA damage. Restoring Apaf-1 induction in p53-deficient neurons is sufficient to overcome XIAP and sensitize cells to cytochrome c. Although a role for p53 in apoptosis upstream of cytochrome c release has been well established, this study uncovers an additional, essential role for p53 in regulating caspase activation downstream of mitochondria following DNA damage in neurons.

Apoptosome dependent caspase-3 activation pathway is non-redundant and necessary for apoptosis in sympathetic neurons

Although sympathetic neurons are a well-studied model for neuronal apoptosis, the role of the apoptosome in activating caspases in these neurons remains debated. We find that the ability of sympathetic neurons to undergo apoptosis in response to nerve growth factor (NGF) deprivation is completely dependent on having an intact apoptosome pathway. Genetic deletion of Apaf-1, caspase-9, or caspase-3 prevents apoptosis after NGF deprivation, and importantly, allows these neurons to recover and survive long-term following readdition of NGF. The inability of caspase-3 deficient sympathetic neurons to undergo apoptosis is particularly striking, as apoptosis in dermal fibroblasts and cortical neurons proceeds even in the absence of caspase-3. Our results show that in contrast to dermal fibroblasts and cortical neurons, sympathetic neurons express no detectable levels of caspase-7. The strict requirement for an intact apoptosome, coupled with a lack of effector caspase redundancy, provides sympathetic neurons with a markedly increased control over their apoptotic pathway.

Safety and Feasibility of Using a Central Venous Catheter for Rapid Contrast Injection Rates

OBJECTIVE

Our aim was to determine the safety and feasibility of using a central venous catheter for rapid contrast injections during CT.

MATERIALS AND METHODS

An in vitro experiment was performed using a 7-French Arrow-Howes multilumen central venous catheter. Each catheter port was tested by varying contrast agent flow rates delivered by a power injector. Contrast media specifications were kept similar to routine clinical practice. The in vivo experiment included 104 cases in which rapid contrast injections, 3.0-5.0 mL/sec, were delivered through a central venous catheter for dynamic CT examinations. Patient monitoring for early complications of contrast extravasation, cardiac arrhythmia, and allergic reactions was performed. Contrast injections were monitored for pressure limitation, automatic flow-rate adjustment, and catheter injury. Chart review was performed for delayed complications of mediastinal hematoma, infection, or catheter malfunction.

RESULTS

During the in vitro experiment, all desired flow rates, 3.0-9.9 mL/sec, could be delivered through the central venous catheter with no catheter injury. No immediate or early patient or catheter complications were observed during the in vivo experiment. Follow-up evaluation revealed that 18 blood cultures and one catheter culture were positive for bacterial growth. In a subgroup of 43 patients, five contrast injections were pressure-limited by the power injector, and only one had the flow rate automatically adjusted to 3.6 mL/sec from 4.0 mL/sec.

CONCLUSION

Rapid contrast injection rates, at 3.0-5.0 mL/sec, through the Arrow-Howes multilumen central venous catheter are feasible and safe in the clinical setting. However, a strict protocol should be followed to avoid possible serious complications.

Caspases in ischaemic brain injury and neurodegenerative disease

The importance of caspases in developmental neuronal death is well-established. Recent data provide compelling evidence of caspase activation after ischaemic brain injury. Caspase inhibitors reduce cell death in several models of ischaemic injury. This review summarizes our current understanding of caspase function in ischaemic brain injury and examines the accumulating evidence of caspase participation in several neurodegenerative diseases. The therapeutic consequences of caspase inhibitor treatment in reducing cell death after such injury are also discussed.

Mitochondrial involvement in the point of no return in neuronal apoptosis

Programmed cell death (PCD) contributes to development, maintenance, and pathology in various tissues, including the nervous system. Many molecular, biochemical, and genetic events occur within cells undergoing PCD. Some of these events are incompatible with long-term cell survival because they have irreversible, catastrophic consequences. The onset of such changes marks the point of no return, a decisive regulatory event termed 'the commitment-to-die.' In this review, we discuss events that underlie the commitment-to-die in nerve growth factor-deprivation-induced death of sympathetic neurons. Findings in this model system implicate the mitochondrion as an important site of regulation for the commitment-to-die in the presence or absence of caspase inhibition.

Burden of morbidities and the unmet need for health care in rural neonates--a prospective observational study in Gadchiroli, India

BACKGROUND

Majority of the neonates in developing countries are born and cared for in rural homes but the available information is mostly hospital based.

OBJECTIVES

To estimate: (i) the incidence of various neonatal morbidities and associated case fatality in home-cared rural neonates, (ii) proportion of neonates with indications for health care, and (iii) the proportion who actually receive it.

DESIGN

Prospective observational study.

SETTING

Rural homes.

METHODS

Neonates in 39 study villages in the Gadchiroli district (Maharashtra, India) were observed during one year (1995-96) by 39 trained female village health workers at birth and during neonatal period (0-28 days) by making eight home visits. A physician checked the data and the morbidities were diagnosed by a computer program. Vital statistics in these villages was independently collected.

RESULTS

Out of 1016 live births, 95% occurred at home and 763 (75&%) neonates were observed. The agreement between observations by health workers and physician was 92%. Total 48.2& neonates suffered high risk morbidities (associated case fatality >10%), 72.2% suffered low risk morbidities, and 17.9% gained inadequate weight (less than 300 g). Seventeen percent neonates developed clinical picture suggestive of sepsis. Though 54.4% neonates had indications for health care and 38 out of total 40 neonatal deaths occurred in these, only 2.6% received medical attention. The neonatal mortality rate was 52.4/1000 live births.

CONCLUSION

Nearly half of the neonates in rural homes developed high risk morbidities ten times the neonatal morbidity rate and needed health care but practically none received it. The magnitude of care gap suggests an urgent need for developing home-based neonatal care to reduce neonatal morbidities and mortality

Significance of HBV DNA by PCR over serological markers of HBV in acute and chronic patients

A study was undertaken to determine Hepatitis B virus DNA (HBV DNA) by PCR in acute and chronic hepatitis B infection and to correlate it with serological markers. Three hundred and forty-five serum samples of patients from all over India were categorized into different groups according to their serological profile. HBV DNA was detected upon amplification in 166/263 patients in group A, 3/14 patients in group B, and 2/32 patients in group C, and was not detected in groups D and E. The presence of HBV DNA in 49 patients with non-replicative HBV disease, as defined by the absence of HBeAg, suggests low levels of viremia which is also supported by the abnormal liver function tests (LFTs) in these patients. In addition, HBV DNA was detected in small proportion of individuals with past HBV infection. This data suggests that, detection of HBV DNA by amplification technique serves as an important supplementary tool besides serology in a number of clinical settings, especially in determining low levels of viremia in patients with non-replicative HBV disease and chronic hepatitis, and also in a few patients with past HBV infection and who could be asymptomatic carriers of HBV infection.

Staurosporine-induced neuronal death: multiple mechanisms and methodological implications

To examine whether multiple pathways of cell death exist in sympathetic neurons, we studied the cell death pathway induced by staurosporine (STS) in sympathetic neurons and compared it with the well-characterized NGF deprivation-induced death pathway. Increasing concentrations of STS were found to induce sympathetic neuronal death with different biochemical and morphological characteristics. One hundred nM STS induced metabolic changes, loss of cytochrome c, and caspase-dependent morphological degeneration which closely resembled the apoptotic death induced by NGF deprivation. In contrast, sympathetic neurons treated with 1 microM STS showed no loss of cytochrome c but exhibited extensive, caspase-independent, chromatin changes that were not TUNEL positive. One microM STS-treated sympathetic neurons had greatly reduced metabolic activities and became committed to die rapidly, yet maintained soma structure and appeared viable by other criteria even up to 48 h after STS treatment, illustrating the need to assess cell death by multiple criteria. Lastly, in contrast to the cell death-inducing activities of 100 nM STS or 1 microM STS, very low concentrations of STS (1 nM STS) inhibited sympathetic neuronal death by acting either at or prior to c-jun phosphorylation in the NGF deprivation-induced PCD pathway.

BDNF blocks caspase-3 activation in neonatal hypoxia-ischemia

Hypoxic-ischemic (H-I) injury to the brain in the perinatal period often leads to significant long-term neurological deficits. In a model of neonatal H-I injury in postnatal day 7 rats, our previous data have shown that cell death with features of apoptosis is prominent between 6 and 24 h after H-I and that neurotrophins, particularly BDNF, can markedly protect against tissue loss. During brain development, caspase-3 is required for normal levels of programmed cell death. Utilizing an antibody specific for the activated form of caspase-3, CM1, we now show that caspase-3 is specifically activated in neuronal cell bodies and their processes beginning at 6 h and peaking 24 h following unilateral carotid ligation and exposure to hypoxia in postnatal day 7 rats. Caspase-3 activation began to occur in cortex at 6 h and in striatum and hippocampus at 12-18 h. Caspase-3 activation was also observed in developing oligodendrocytes. Intracerebroventricular injection of BDNF prior to H-I injury almost completely abolished evidence of H-I-induced caspase-3 activation in vivo. Utilizing a specific molecular marker of an apoptotic pathway, these findings demonstrate that H-I injury to the developing brain is a strong apoptotic stimulus leading to caspase-3 activation, that BDNF can block this process in vivo, and that the ability of BDNF to inhibit caspase activation and subsequent apoptosis likely accounts in large part for its protection against neuronal injury in this model.

Novel Rhodobacter capsulatus genes required for the biogenesis of various c-type cytochromes

Following chemical mutagenesis and screening for the inability to grow by photosynthesis and the absence of cyt cbb3 oxidase activity, two c-type cytochrome (cyt)-deficient mutants, 771 and K2, of Rhodobacter capsulatus were isolated. Both mutants were completely deficient in all known c-type cyts, and could not be complemented by the previously known cyt c biogenesis genes of R. capsulatus. Complementation of 771 and K2 with a wild-type chromosomal library led to the identification of two novel genes, cycJ and ccdA respectively. The cycJ is highly homologous to ccmE/cycJ, encountered in various Gram-negative species. Unlike in other species, where cycJ is a part of an operon essential for cyt c biogenesis, in R. capsulatus, it is located immediately downstream from argC, involved in arginine biosynthesis. Mutation of its universally conserved histidine residue, which is critical for its proposed haem chaperoning role, to an alanine led to loss of its function. All R. capsulatus cycJ mutants studied so far excrete copious amounts of coproporphyrin and protoporphyrin when grown on enriched media, suggesting that its product is also a component of the haem delivery branch of cyt c biogenesis in this species. In contrast, the R. capsulatus ccdA was homologous to the cyt c biogenesis gene ccdA, found in the gram-positive bacterium Bacillus subtilis, and to the central region of dipZ, encoding a protein disulphide reductase required for cyt c biogenesis in Escherichia coli. Membrane topology of CcdA was established in R. capsulatus using ccdA:phoA and ccdA :lacZ gene fusions. The deduced topology revealed that the two conserved cysteine residues of CcdA are, as predicted, membrane embedded. Mutagenesis of these cysteines showed that both are required for the function of CcdA in cyt c biogenesis. This study demonstrated for the first time that CcdA homologues are also required for cyt c biogenesis in some gram-negative bacteria such as R. capsulatus.

Reversible physiological alterations in sympathetic neurons deprived of NGF but protected from apoptosis by caspase inhibition or Bax deletion

Cell death in nervous system development and in many neurodegenerative diseases appears to be apoptotic or programmed. Withdrawal of nerve growth factor (NGF) from cultures of superior cervical ganglia neurons (SCG) is an excellent model of programmed cell death (PCD), producing apoptosis within 24-48 h. This death can be prevented by treatment with caspase inhibitors or deletion of the proapoptotic Bax gene. Since inhibition of apoptosis is an attractive strategy for the therapy of many neurological diseases and little is known about the function of neurons when apoptosis has been aborted, we examined the electrophysiological properties of NGF-deprived SCG neurons from rats and mice, saved by the caspase inhibitor boc-aspartyl(OMe)fluoromethyl ketone (BAF) or by Bax deletion. Compared to NGF-maintained controls, the resting membrane potentials of BAF-saved neurons were depolarized by 9 mV and the action potentials were prolonged by over 50%. Nicotinic cholinergic current density was depressed by about 50%. Electrophysiological parameters returned to normal within 4 days after NGF restoration. Neurons from Bax-deficient mice were altered differently by NGF withdrawal. There were no detectable changes in resting or action potentials. However, nicotinic current density was reduced just as in BAF-saved rat neurons. There were no observable changes in the processes of individual neurons after 6 days of NGF deprivation in the presence of BAF. Our results indicate that neurons are physiologically altered during pharmacological inhibition of PCD, but fully recover after trophic support is returned.

BAX translocation is a critical event in neuronal apoptosis: regulation by neuroprotectants, BCL-2, and caspases

Members of the BCL-2 family of proteins either promote or repress programmed cell death. Here we report that neonatal sympathetic neurons undergoing apoptosis after nerve growth factor (NGF) deprivation exhibited a protein synthesis-dependent, caspase-independent subcellular redistribution of BAX from cytosol to mitochondria, followed by a loss of mitochondrial cytochrome c and cell death. Treatment with elevated concentrations of the neuroprotectants KCl or cAMP at the time of deprivation prevented BAX translocation and cytochrome c release. However, administration of KCl or cAMP 12 hr after NGF withdrawal acutely prevented loss of mitochondrial cytochrome c, but not redistribution of BAX; rescue with NGF acutely prevented both events. Overexpression of Bcl-2 neither altered the normal subcellular localization of BAX nor prevented its redistribution with deprivation but did inhibit the subsequent release of cytochrome c, caspase activation, and cell death. Bcl-2 overexpression did not prevent cell death induced by cytoplasmic microinjection of cytochrome c into NGF-deprived competent-to-die neurons. These observations suggest that the subcellular redistribution of BAX is a critical event in neuronal apoptosis induced by trophic factor deprivation. BCL-2 acts primarily, if not exclusively, at the level of mitochondria to prevent BAX-mediated cytochrome c release, whereas NGF, KCl, or cAMP may abort the apoptotic program at multiple checkpoints.

Evidence of a novel event during neuronal death: development of competence-to-die in response to cytoplasmic cytochrome c

Sympathetic neurons undergoing programmed cell death after nerve growth factor (NGF) deprivation are shown to exhibit a protein synthesis-dependent, BAX-dependent loss of cytochrome c from the mitochondria. However, cytoplasmic microinjection of cytochrome c was insufficient to induce cell death in NGF-maintained sympathetic neurons. In contrast, microinjection of cytochrome c rapidly induced a caspase-dependent death in NGF-deprived, Bax-deficient or NGF-deprived, cycloheximide-treated neurons. Cells needed to be deprived of NGF for 15-20 hr before they acquired competence to die with injection of cytochrome c. These data suggest that NGF deprivation induced the translocation of cytochrome c and another event, which we term as competence-to-die, that was independent of macromolecular synthesis and BAX function. Both these processes were required for neurons to undergo apoptosis.

Caspase inhibitor affords neuroprotection with delayed administration in a rat model of neonatal hypoxic-ischemic brain injury

Programmed cell death (apoptosis) is a normal process in the developing nervous system. Recent data suggest that certain features seen in the process of programmed cell death may be favored in the developing versus the adult brain in response to different brain injuries. In a well characterized model of neonatal hypoxia-ischemia, we demonstrate marked but delayed cell death in which there is prominent DNA laddering, TUNEL-labeling, and nuclei with condensed chromatin. Caspase activation, which is required in many cases of apoptotic cell death, also followed a delayed time course after hypoxia-ischemia. Administration of boc-aspartyl(OMe)-fluoromethylketone, a pan-caspase inhibitor, was significantly neuroprotective when given by intracerebroventricular injection 3 h after cerebral hypoxia-ischemia. In addition, systemic injections of boc-aspartyl(OMe)-fluoromethylketone also given in a delayed fashion, resulted in significant neuroprotection. These findings suggest that caspase inhibitors may be able to provide benefit over a prolonged therapeutic window after hypoxic-ischemic events in the developing brain, a major contributor to static encephalopathy and cerebral palsy.

Bax deletion further orders the cell death pathway in cerebellar granule cells and suggests a caspase-independent pathway to cell death

Dissociated cerebellar granule cells maintained in medium containing 25 mM potassium undergo an apoptotic death when switched to medium with 5 mM potassium. Granule cells from mice in which Bax, a proapoptotic Bcl-2 family member, had been deleted, did not undergo apoptosis in 5 mM potassium, yet did undergo an excitotoxic cell death in response to stimulation with 30 or 100 microM NMDA. Within 2 h after switching to 5 mM K+, both wild-type and Bax-deficient granule cells decreased glucose uptake to <20% of control. Protein synthesis also decreased rapidly in both wild-type and Bax-deficient granule cells to 50% of control within 12 h after switching to 5 mM potassium. Both wild-type and Bax -/- neurons increased mRNA levels of c-jun, and caspase 3 (CPP32) and increased phosphorylation of the transactivation domain of c-Jun after K+ deprivation. Wild-type granule cells in 5 mM K+ increased cleavage of DEVD-aminomethylcoumarin (DEVD-AMC), a fluorogenic substrate for caspases 2, 3, and 7; in contrast, Bax-deficient granule cells did not cleave DEVD-AMC. These results place BAX downstream of metabolic changes, changes in mRNA levels, and increased phosphorylation of c-Jun, yet upstream of the activation of caspases and indicate that BAX is required for apoptotic, but not excitotoxic, cell death. In wild-type cells, Boc-Asp-FMK and ZVAD-FMK, general inhibitors of caspases, blocked cleavage of DEVD-AMC and blocked the increase in TdT-mediated dUTP nick end labeling (TUNEL) positivity. However, these inhibitors had only a marginal effect on preventing cell death, suggesting a caspase-independent death pathway downstream of BAX in cerebellar granule cells.

Programmed cell death in neurons: focus on the pathway of nerve growth factor deprivation-induced death of sympathetic neurons

Extensive programmed cell death (PCD) occurs in the developing nervous system. Neuronal death occurs, at least in part, because neurons are produced in excess during development and compete with each other for the limited amounts of the survival-promoting trophic factors secreted by target tissues. Neuronal death is apoptotic and utilizes components that are conserved in other PCD pathways. In this review, we discuss the mechanism of trophic factor-dependent neuronal cell death by focusing on the pathway of nerve growth factor (NGF) deprivation-induced sympathetic neuronal death. We describe the biochemical and genetic events that occur in NGF-deprived sympathetic neurons undergoing PCD. Participation of the Bcl-2 family of proteins and the interleukin-1beta-converting enzyme family of proteases (caspases) in this and other models of neuronal death is also examined. The order and importance of these components during NGF deprivation-induced sympathetic neuronal death are discussed.

Genetic and metabolic status of NGF-deprived sympathetic neurons saved by an inhibitor of ICE family proteases

Sympathetic neurons undergo programmed cell death (PCD) when deprived of NGF. We used an inhibitor to examine the function of interleukin-1 beta-converting enzyme (ICE) family proteases during sympathetic neuronal death and to assess the metabolic and genetic status of neurons saved by such inhibition. Bocaspartyl(OMe)-fluoromethylketone (BAF), a cell-permeable inhibitor of the ICE family of cysteine proteases, inhibited ICE and CPP32 (IC50 approximately 4 microM) in vitro and blocked Fas-mediated apoptosis in thymocytes (EC50 approximately 10 microM). At similar concentrations, BAF also blocked the NGF deprivation-induced death of rat sympathetic neurons in culture. Compared to NGF-maintained neurons, BAF-saved neurons had markedly smaller somas and maintained only basal levels of protein synthesis; readdition of NGF restored growth and metabolism. Although BAF blocked apoptosis in sympathetic neurons, it did not prevent the fall in protein synthesis or the increase in the expression of c-jun, c-fos, and other mRNAs that occur during neuronal PCD, implying that the ICE-family proteases function downstream of these events during PCD.NGF and BAF rescued sympathetic neurons with an identical time course, suggesting that NGF, in addition to inhibiting metabolic and genetic events associated with neuronal PCD, can act posttranslationally to abort apoptosis at a time point indistinguishable from the activation of cysteine proteases. Both poly-(ADP ribose) polymerase and pro-ICE and Ced-3 homolog-1 (ICH-1) appear to be cleaved in a BAF-inhibitable manner, although the majority of pro-CPP32 appears unchanged, suggesting that ICH-1 is activated during neuronal PCD. Potential implications of these findings for anti-apoptotic therapies are discussed.

Neuronal death in developmental models: possible implications in neuropathology

Extensive neuronal death occurs in the developing nervous system. Death of neurons during this process is apoptotic and appears to utilize a pathway that is conserved in various mammalian cells and organisms. Recent evidence suggests that neuronal death during trauma, stroke, or neurodegenerative diseases may also occur by a similar mechanism. This review discusses the molecular mechanism of developmental neuronal death by examining the biochemical and molecular events associated with neuronal death after trophic factor withdrawal. The ability to inhibit neuronal death by manipulating the Bcl-2 or the ICE-family proteins demonstrates the importance of these proteins in the neuronal apoptotic pathway. The utility of inhibiting neuronal death by blocking the apoptotic pathway as therapy in neuropathological situations is discussed.

Involvement of lysine 270 and lysine 271 of yeast 5S rRNA binding protein in RNA binding and ribosome assembly

Contributions of the highly conserved K270 and its neighboring K271 in the C-terminal region of the yeast ribosomal protein L1 to 5S rRNA binding and ribosome assembly were examined by in vivo and in vitro studies on the consequences of 14 substitution mutations. All mutant proteins with a single amino-acid substitution at either position were able to bind 5S rRNA in vitro to an extent comparable to the wild-type. Yeast cells expressing these mutant proteins, except the K270G mutant, grew at nearly normal rates. Mutations of K270 appeared to produce more demonstrable effects than those of K271. The double mutant K270,271G bound RNA poorly and yeast cells expressing the mutant protein grew 30% slower. Double mutants K270,271E and K270,271R were lethal, although the mutant protein was assembled into the 60S ribosomal subunits. The resultant subunits were not stable leading eventually to cell death. The in vitro RNA binding ability of the respective protein was reduced by 60% and 20%. Taken together, the present data identified K270 and K271 as important amino-acid residues in the function of the yeast ribosomal protein L1.

Multiple regions of yeast ribosomal protein L1 are important for its interaction with 5 S rRNA and assembly into ribosomes

Yeast ribosomal protein L1 binds to 5 S rRNA and can be released from 60 S ribosomal subunits as an intact ribonucleoprotein particle. To identify residues important for binding of Saccharomyces cerevisiae rpL1 to 5 S rRNA and assembly into functional ribosomes, we have isolated mutant alleles of the yeast RPL1 gene by site-directed and random mutagenesis. The rpl1 mutants were assayed for association of rpL1 with 5 S rRNA in vivo and in vitro and assembly of rpL1 into functional 60 S ribosomal subunits. Consistent with previous data implicating the importance of the carboxyl-terminal 47 amino acids of rpL1 for binding to 5 S rRNA in vitro, we find that deletion of the carboxyl-terminal 8, 25, or 44 amino acids of rpL1 confers lethality in vivo. Missense mutations elsewhere in rpL1 also affect its function, indicating that multiple regions of rpL1 are important for its association with 5 S rRNA and assembly into ribosomes.

TIF4631 and TIF4632: two yeast genes encoding the high-molecular-weight subunits of the cap-binding protein complex (eukaryotic initiation factor 4F) contain an RNA recognition motif-like sequence and carry out an essential function

The 5' ends of eukaryotic mRNAs are blocked by a cap structure, m7GpppX (where X is any nucleotide). The interaction of the cap structure with a cap-binding protein complex is required for efficient ribosome binding to the mRNA. In Saccharomyces cerevisiae, the cap-binding protein complex is a heterodimer composed of two subunits with molecular masses of 24 (eIF-4E, CDC33) and 150 (p150) kDa. p150 is presumed to be the yeast homolog of the p220 component of mammalian eIF-4F. In this report, we describe the isolation of yeast gene TIF4631, which encodes p150, and a closely related gene, TIF4632. TIF4631 and TIF4632 are 53% identical overall and 80% identical over a 320-amino-acid stretch in their carboxy-terminal halves. Both proteins contain sequences resembling the RNA recognition motif and auxiliary domains that are characteristic of a large family of RNA-binding proteins. tif4631-disrupted strains exhibited a slow-growth, cold-sensitive phenotype, while disruption of TIF4632 failed to show any phenotype under the conditions assayed. Double gene disruption engendered lethality, suggesting that the two genes are functionally homologous and demonstrating that at least one of them is essential for viability. These data are consistent with a critical role for the high-molecular-weight subunit of putative yeast eIF-4F in translation. Sequence comparison of TIF4631, TIF4632, and the human eIF-4F p220 subunit revealed significant stretches of homology. We have thus cloned two yeast homologs of mammalian p220.

Yeast ribosomal protein L1 is required for the stability of newly synthesized 5S rRNA and the assembly of 60S ribosomal subunits

Ribosomal protein L1 from Saccharomyces cerevisiae binds 5S rRNA and can be released from intact 60S ribosomal subunits as an L1-5S ribonucleoprotein (RNP) particle. To understand the nature of the interaction between L1 and 5S rRNA and to assess the role of L1 in ribosome assembly and function, we cloned the RPL1 gene encoding L1. We have shown that RPL1 is an essential single-copy gene. A conditional null mutant in which the only copy of RPL1 is under control of the repressible GAL1 promoter was constructed. Depletion of L1 causes instability of newly synthesized 5S rRNA in vivo. Cells depleted of L1 no longer assemble 60S ribosomal subunits, indicating that L1 is required for assembly of stable 60S ribosomal subunits but not 40S ribosomal subunits. An L1-5S RNP particle not associated with ribosomal particles was detected by coimmunoprecipitation of L1 and 5S rRNA. This pool of L1-5S RNP remained stable even upon cessation of 60S ribosomal subunit assembly by depletion of another ribosomal protein, L16. Preliminary results suggest that transcription of RPL1 is not autogenously regulated by L1.