Neurotoxicity induces cleavage of p35 to p25 by calpain

Cyclin-dependent kinase 5 (cdk5) and its neuron-specific activator p35 are required for neurite outgrowth and cortical lamination. Proteolytic cleavage of p35 produces p25, which accumulates in the brains of patients with Alzheimer's disease. Conversion of p35 to p25 causes prolonged activation and mislocalization of cdk5. Consequently, the p25/cdk5 kinase hyperphosphorylates tau, disrupts the cytoskeleton and promotes the death (apoptosis) of primary neurons. Here we describe the mechanism of conversion of p35 to p25. In cultured primary cortical neurons, excitotoxins, hypoxic stress and calcium influx induce the production of p25. In fresh brain lysates, addition of calcium can stimulate cleavage of p35 to p25. Specific inhibitors of calpain, a calcium-dependent cysteine protease, effectively inhibit the calcium-induced cleavage of p35. In vitro, calpain directly cleaves p35 to release a fragment with relative molecular mass 25,000. The sequence of the calpain cleavage product corresponds precisely to that of p25. Application of the amyloid beta-peptide A beta(1-42) induces the conversion of p35 to p25 in primary cortical neurons. Furthermore, inhibition of cdk5 or calpain activity reduces cell death in A beta-treated cortical neurons. These observations indicate that cleavage of p35 to p25 by calpain may be involved in the pathogenesis of Alzheimer's disease.

Interaction between protein tyrosine phosphatase and protein tyrosine kinase is involved in androgen-promoted growth of human prostate cancer cells

Steroid hormones play key roles in regulating cell proliferation and differentiation in targeting tissues. However, in advanced cancers, the steroid hormone regulation is frequently attenuated through a yet unknown mechanism even in the presence of functional steroid hormone receptors. We investigate the functional role of tyrosine phosphorylation signaling in the hormone-refractory growth of human prostate tumors. Initial studies demonstrate that the androgen-responsive phenotype of human prostate cancer cells associates with a low phosphotyrosine (p-Tyr) level of ErbB-2, which is regulated by cellular prostatic acid phosphatase (PAcP), a protein tyrosine phosphatase. In prostate cancer cells, the p-Tyr level, but not the protein level, of ErbB-2 inversely correlates with the androgen-responsiveness of cell proliferation. Androgen-stimulated cell growth concurs with a down-regulation of cellular PAcP, an elevated p-Tyr level of ErbB-2, and the activation of mitogen-activated protein kinases. Furthermore, only the ErbB-2 inhibitor AG 879, but not the EGFR inhibitor AG 1478, abolishes androgen-induced cell proliferation. Forced expression of ErbB-2 can also attenuate androgen promotion of cell growth. Data taken collectively conclude that in human prostate cancer cells, the tyrosine phosphorylation of ErbB-2 regulated by cellular PAcP plays a key role in regulating androgen-mediated proliferation signaling. Oncogene (2000).

Hyperosmotic pressure enhances immunoglobulin transcription rates and secretion rates of KR12H-2 transfectoma

When subjected to hyperosmotic pressure resulting from NaCl addition, KR12H-2 transfectoma, like most hybridomas, displayed a decrease in specific growth rate (mu) and an increase in specific antibody productivity (q(Ab)). Elevation of medium osmolality from 285 to 425 mOsm/kg decreased mu by 20%, while it increased q(Ab) by 376%. Although cell mass also increased at higher osmolality, it was not the main factor in increasing q(Ab). Hyperosmotic pressure was found to enhance transcription levels of immunoglobulin (Ig) mRNAs preferentially, compared with non-IgG mRNA. The transcription levels of both heavy chain (HC) and light chain (LC) mRNAs were enhanced as much as q(Ab). This result suggests that enhanced q(Ab) at higher osmolality was mainly due to enhanced transcription levels of Ig mRNA. However, these increased transcription levels of Ig mRNAs were not due to the enhanced stability of Ig mRNA. In fact, the stability of Ig mRNAs decreased at higher osmolality. Elevation of osmolality from 285 mOsm/kg to 425 mOsm/kg decreased the half-lives of HC and LC mRNAs by 37% and 36%, respectively. A simple mathematical model revealed that transcription rates of Ig mRNAs increased by more than 476% at 425 mOsm/kg. These elevated transcription levels could, in turn, increase the translation rates of Ig polypeptides. However, the translation rates of Ig polypeptides were not enhanced as much as the transcription levels of Ig mRNAs and q(Ab). The elevation of osmolality from 285 mOsm/kg to 425 mOsm/kg increased HC and LC mRNA specific translation rates by 172% and 240%, respectively. Taken together, the data suggest that (1) enhanced q(Ab) of KR12H-2 transfectoma at higher osmolality is due to elevated transcription rates of Ig mRNAs and expedited post-translational processing of Ig, and (2) antibody secretion by KR12H-2 transfectoma is most likely controlled at the level of Ig translation, particularly HC translation.

Effect of Qi-training on blood pressure, heart rate and respiration rate

To examine the physiological effects of Korean traditional Qi-training, we investigated the changes in blood pressure, heart and respiratory rates before, during and after ChunDoSunBup (CDSB) Qi-training. Twelve normal healthy CDSB Qi-trainees (19-37 years old; trained for 1.3 +/- 0.2 years; 9 men and 3 women) volunteered to participate in this study. Heart rate, respiratory rate, systolic blood pressure and rate-pressure product were significantly decreased during Qi-training. From these results, we suggest that CDSB Qi-training has physiological effects that indicate stabilization of cardiovascular system.

Significance of Pro12Ala mutation in peroxisome proliferator-activated receptor-gamma2 in Korean diabetic and obese subjects

Peroxisome proliferator-activated receptors (PPARs) are a nuclear hormone receptor superfamily of ligand-activated transcription factors, and the PPARgamma subtype regulates adipocyte differentiation, lipid metabolism, and insulin sensitivity. There have been several reports on the relationship between the PPARgamma2 Pro12Ala genotype and obesity or diabetes in Caucasians. The objective of this study was to examine the relationship between this mutation and obesity or diabetes in Korean subjects. Two hundred and twenty-nine Korean subjects, including 111 obese subjects (body mass index, >25 kg/m2) were included in this study. One hundred and eleven subjects had normal glucose tolerance, 60 had impaired glucose tolerance, and 58 had diabetes mellitus. We evaluated these subjects for the Pro12Ala mutation in the PPARgamma gene using PCR-restriction fragment length polymorphism. Allele frequencies of the Pro12Ala missense mutation of PPARgamma2 were not different among Korean subjects with normal glucose tolerance (qAla = 0.045), those with impaired glucose tolerance (qAla = 0.033), and those with diabetes mellitus (qAla = 0.043; P > 0.05). Allele frequencies of PPARgamma2 Ala in obese subjects (qAla = 0.036) were not significantly different from those in nonobese subjects (qAla = 0.047). These results suggest that the Pro12Ala mutation in PPARgamma is not associated with either diabetes or obesity and may not be an important determinant of obesity or diabetes in Korean subjects.

Absolute and relative energies from polarized atomic orbital self-consistent field calculations and a second order correction. Convergence with size and composition of the secondary basis

Polarized atomic orbitals (PAO's) are molecule-adapted minimal basis functions that are variationally obtained as an atom-blocked transformation from a conventional extended basis set, as a Hartree-Fock calculation is performed in the PAO basis. This approximation yields a higher energy than a HF calculation performed in the extended basis, although the two results converge to the same limit as the extended basis approaches completeness on each atom. To test the rate of convergence, PAO-HF calculations were performed using cc-pVXZ and aug-cc-pVXZ basis sets for the water monomer and dimer, and six substituted ethylenes. The results show that the quality of PAO calculations converges smoothly with X. The use of augmented functions is recommended. To correct a PAO-HF calculation for residual deficiencies, a noniterative second order correction is introduced. This correction corresponds to an energy-weighted steepest descent step, and substantially improves the quality of PAO energies.

Molecular response assessed by PCR is the most important factor predicting failure-free survival in indolent follicular lymphoma: update of the MDACC series

BACKGROUND

We have observed that molecular response, as defined by a PCR-negative status during the first year of therapy, along with beta 2-microglobulin (beta 2M), was the most important variable associated with failure-free survival (FFS) in follicular lymphoma (FL). Herein, we present an update of the previously published MDACC series.

PATIENTS AND METHODS

A total of 116 patients (male:female ratio 64:52; median age: 52 years) with indolent FL and BCL-2 rearrangement (at MBR or mcr breakpoints) assessable in peripheral blood (pb) by PCR prior to treatment, and with two or more PCR determinations during the first year, were selected for the present study.

RESULTS

Of the 116 patients, 4 who presented with progression and 1 who died of unrelated causes during the first year were excluded from the landmark analysis. One hundred patients (86%) achieved clinical CR and 80 (69%) achieved a negative PCR status within first year. Median FFS was 6.4 years. Five-year FFS was 73% and 28% for molecular responders and nonresponders, respectively (P = 0.001). In spite of this strikingly higher FFS favoring molecular responders, no clearcut plateau was evident in this group. Molecular response assessed in pb (P = 0.001) and serum beta 2M (P < 0.001) were the most important factors to predict FFS in the multivariate analysis. In the subset of patients with normal beta 2M and molecular CR, there was a trend for a plateau in the FFS curve. No significant difference between the groups has been observed so far in terms of survival.

CONCLUSIONS

Molecular response assessed in pb using a PCR technique is, along with beta 2M, the most important factor to predict FFS in FL.

Clinical implication of altered expression of Mad1 protein in human breast carcinoma

BACKGROUND

Mad1 protein is known to repress Myc target genes and antagonize Myc function. The authors undertook this study to investigate the clinical implication of Mad1 expression in human breast carcinoma.

METHODS

The authors performed immunohistochemical assays for Mad1 and Myc proteins in human breast carcinoma, along with tissues from normal breast and benign diseases. The data from protein assays were analyzed in terms of the clinical and biologic characteristics of the patients.

RESULTS

Of 66 patients with invasive ductal carcinoma, Mad1 expression was detected in 22 (33. 3%). Intensity and area of Mad1 expression significantly decreased in DCIS and invasive cancers, whereas high levels of Mad1 expression were persistent in benign breast lesions. Mad1 expression was significantly reduced in poorly differentiated tumors (P < 0.001). Expression of Mad1 was not associated with tumor size, lymph node status, or stage of disease. The authors did not observe any correlation between S-phase and expression status of Myc or Mad1. Mad1 expression was closely linked to differentiation of the cancer cells and inversely correlated with Myc expression (P = 0.042). In survival analysis, Mad1 was a significant factor in predicting recurrence of the disease, but not overall survival after CMF chemotherapy.

CONCLUSIONS

In human breast carcinoma cells, expression of Mad1 seems to be down-regulated, whereas expression of Myc is amplified. Altered expression of Mad1 may play a role in the malignant transformation of human mammary epithelial cells and represent an aggressive phenotype in human breast carcinoma.

The pedunculopontine nucleus: its role in the genesis of movement disorders

The pedunculopontine nucleus (PPN) is located in the dorso-lateral part of the ponto-mesencephalic tegmentum. The PPN is composed of two groups of neurons: one containing acetylcholine, and the other containing non-cholinergic neurotransmitters (GABA, glutamate). The PPN is connected reciprocally with the limbic system, the basal ganglia nuclei (globus pallidus, substantia nigra, subthalamic nucleus), and the brainstem reticular formation. The caudally directed corticolimbic-ventral striatal-ventral pallidal-PPN-pontomedullary reticular nuclei-spinal cord pathway seems to be involved in the initiation, acceleration, deceleration, and termination of locomotion. This pathway is under the control of the deep cerebellar and basal ganglia nuclei at the level of the PPN, particularly via potent inputs from the medial globus pallidus, substantia nigra pars reticulata and subthalamic nucleus. The PPN sends profuse ascending cholinergic efferent fibers to almost all the thalamic nuclei, to mediate phasic events in rapid-eye-movement sleep. Experimental evidence suggests that the PPN, along with other brain stem nuclei, is also involved in anti-nociception and startle reactions. In idiopathic Parkinson's disease (IPD) and parkinson plus syndrome, overactive pallidal and nigral inhibitory inputs to the PPN may cause sequential occurrences of PPN hypofunction, decreased excitatory PPN input to the substantia nigra, and aggravation of striatal dopamine deficiency. In addition, neuronal loss in the PPN itself may cause dopamine-resistant parkinsonian deficits, including gait disorders, postural instability and sleep disturbances. In patients with IPD, such deficits may improve after posteroventral pallidotomy, but not after thalamotomy. One of the possible explanations for such differences is that dopamine-resistant parkinsonian deficits are mediated to the PPN by the descending pallido-PPN inhibitory fibers, which leave the pallido-thalamic pathways before they reach the thalamic targets.

Comparison of single and multiple sessions of percutaneous sclerotherapy for simple renal cyst

OBJECTIVE

To compare the results of single and repeated percutaneous sclerotherapy in patients with simple renal cysts.

PATIENTS AND METHODS

Eighty-two patients with simple renal cysts underwent needle aspiration andsclerotherapy under ultrasonographic guidance. Forty-two patients (group 1) underwent one session of sclerotherapy with 99% ethanol immediately after aspiration and 40 patients (group 2) underwent sclerotherapy at least twice. The patients were followed up using ultrasonography at 3-month intervals. The complete disappearance or a reduction of more than half in the diameter of the renal cyst was considered a successful treatment.

RESULTS

The mean diameter of the renal cysts was not significantly different in group 1 (6.12 cm) and 2 (6.75 cm). There was complete or partial regression in eight (19%) and 16 (38%) in group 1, and in 29 (73%) and nine (23%) in group 2, respectively. The overall success rate was significantly better in group 2 (95%) than in group 1 (57%; P < 0.001).

CONCLUSIONS

These results suggest that multiple sclerotherapy is better than a single injection of sclerosant for reducing the recurrence of simple renal cysts.

Inhibition of autoimmune diabetes by Fas ligand: the paradox is solved

Previous reports that diabetogenic lymphocytes did not induce diabetes in nonobese diabetic (NOD)-lpr mice suggested the critical role of Fas-Fas ligand (FasL) interaction in pancreatic beta cell apoptosis. However, recent works demonstrated that FasL is not an effector molecule in islet beta cell death. We addressed why diabetes cannot be transferred to NOD-lpr mice despite the nonessential role of Fas in beta cell apoptosis. Lymphocytes from NOD-lpr mice were constitutively expressing FasL. A decrease in the number of FasL+ lymphocytes by neonatal thymectomy facilitated the development of insulitis. Cotransfer of FasL+ lymphocytes from NOD-lpr mice completely abrogated diabetes after adoptive transfer of lymphocytes from diabetic NOD mice. The inhibition of diabetes by cotransferred lymphocytes was reversed by anti-FasL Ab, indicating that FasL on abnormal lymphocytes from NOD-lpr mice was responsible for the inhibition of diabetes transfer. Pretreatment of lymphocytes with soluble FasL (sFasL) also inhibited diabetes transfer. sFasL treatment decreased the number of CD4+CD45RBlow cells and increased the number of propidium iodide-stained cells among CD4+CD45RBlow cells, suggesting that sFasL induces apoptosis on CD4+CD45RBlow "memory" cells. These results resolve the paradox between previous findings and suggest a new role for FasL in the treatment of autoimmune disorders. Our data also suggest that sFasL is involved in the deletion of potentially hazardous peripheral "memory" cells, contrary to previous reports that Fas on unmanipulated peripheral lymphocytes is nonfunctional.

Clinical results of Ahmed glaucoma valve implantation in refractory glaucoma with adjunctive mitomycin C

OBJECTIVE

To study the surgical outcome and complications of Ahmed glaucoma valve (AGV) implantation with mitomycin C (MMC) in refractory glaucoma.

PATIENTS AND METHODS

The authors retrospectively reviewed the records of 40 eyes in 37 consecutive patients who underwent combined AGV with MMC (0.4 mg/mL; 5 minutes). All patients had a minimum of 6 months of follow-up. Outcome measures were best corrected visual acuity, intraocular pressure (IOP), the number of medications, success rates, and the incidence of complications.

RESULTS

The Kaplan-Meier life table analysis revealed that the probabilities of surgical success based on our success criteria at 1 year and 2 years postoperatively were 80% and 77%, respectively. Postoperative IOP was significantly lower at all follow-up intervals. At the final visit fewer glaucoma medications were used (2.5 vs 0.7, preoperative vs postoperative). The most frequent complication was hypotony (17%).

CONCLUSION

In this retrospective case series with relatively short follow-ups, AGV implantation with mitomycin C in refractory glaucoma appears to be effective without increased complication rates.

Autosomal dominant growth hormone (GH) deficiency type II: the Del32-71-GH deletion mutant suppresses secretion of wild-type GH

Familial isolated GH deficiency type II is an autosomal dominant form of short stature, associated in some families with mutations that result in missplicing to produce del32-71-GH, a protein that cannot fold normally. The mechanism by which this mutant suppresses the secretion of wild-type GH encoded by the normal allele is not known. Coexpression of del32-71-GH with wild-type human GH in transient transfections of the neuroendocrine cell lines GH4C1 and AtT20 suppressed accumulation of wild-type GH. The suppression of wild-type GH accumulation by del32-71-GH was a posttranslational effect on wild-type GH caused by decreased stability, rather than decreased synthesis, of wild-type GH. Coexpression of del32-71-GH with human PRL did not suppress accumulation of PRL, indicating that there was not a general suppression of secretory pathway function. Accumulation of del32-71-GH protein was not necessary for the suppression of wild-type GH, because del32-71-GH did not accumulate in the neuroendocrine cell lines in which suppression of accumulation of wild-type GH was observed. Del32-71-GH did accumulate in transfected COS and CHO cells, but did not suppress the accumulation of wild-type GH in these cells. These studies suggest that del32-71-GH may cause GH deficiency in somatotropes of heterozygotes expressing both wild-type and del32-71-GH by decreasing the intracellular stability of wild-type GH.

Zinc as a paracrine effector in pancreatic islet cell death

Because of a huge amount of Zn2+ in secretory granules of pancreatic islet beta-cells, Zn2+ released in certain conditions might affect the function or survival of islet cells. We studied potential paracrine effects of endogenous Zn2+ on beta-cell death. Zn2+ induced insulinoma/islet cell death in a dose-dependent manner. Chelation of released endogenous Zn2+ by CaEDTA significantly decreased streptozotocin (STZ)-induced islet cell death in an in vitro culture system simulating in vivo circumstances but not in the conventional culture system. Zn2+ chelation in vivo by continuous CaEDTA infusion significantly decreased the incidence of diabetes after STZ administration. N-(6-methoxy-quinolyl)-para-toluene-sulfonamide staining revealed that Zn2+ was densely deposited in degenerating islet cells 24 h after STZ treatment, which was decreased by CaEDTA infusion. We show here that Zn2+ is not a passive element for insulin storage but an active participant in islet cell death in certain conditions, which in time might contribute to the development of diabetes in aged people.

Clustering of breast microcalcifications: revisited

AIM

To verify the diagnostic value of the traditional definition of 'clustering' of microcalcifications (more than five in the area of 1 cm(2)or 1 cm(3)) on mammography in the differential diagnosis of benign and malignant breast disease.

METHODS AND MATERIALS

Three radiologists without knowledge of the final pathology retrospectively counted the number of microcalcifications per 0.25 cm(2) (0.5 x 0.5 cm) unit area on mammography in 57 pathologically proven non-palpable lesions including 26 cancers and 31 benign diseases. Pleomorphism of the microcalcifications, associated architectural distortion or mass or increased density and distribution of microcalcifications were also evaluated.

RESULTS

The mean numbers of microcalcifications per 0.25 cm(2) were 16.4 in malignant and 16.7 in benign diseases (no statistically significant difference between the two groups). Pleomorphism of the microcalcifications, associated architectural distortion or mass or increased density were, however, important determining parameters. Clustering was more frequently observed in benign diseases.

CONCLUSION

In this study, the mean number of microcalcifications per unit area is much larger than the traditional definition of 'clustering' and clustering itself is not effective in the differential diagnosis of benign and malignant breast lesions. Imaging features other than numbers of calcification per unit area are more important in assessing the significance of mammographic clustered microcalcifications.

The Pleistocene serpent Wonambi and the early evolution of snakes

The Madtsoiidae were medium sized to gigantic snakes with a fossil record extending from the mid-Cretaceous to the Pleistocene, and spanning Europe, Africa, Madagascar, South America and Australia. This widely distributed group survived for about 90 million years (70% of known ophidian history), and potentially provides important insights into the origin and early evolution of snakes. However, madtsoiids are known mostly from their vertebrae, and their skull morphology and phylogenetic affinities have been enigmatic. Here we report new Australian material of Wonambi, one of the last-surviving madtsoiids, that allows the first detailed assessment of madtsoiid cranial anatomy and relationships. Despite its recent age, which could have overlapped with human history in Australia, Wonambi is one of the most primitive snakes known--as basal as the Cretaceous forms Pachyrhachis and Dinilysia. None of these three primitive snake lineages shows features associated with burrowing, nor do any of the nearest lizard relatives of snakes (varanoids). These phylogenetic conclusions contradict the widely held 'subterranean' theory of snake origins, and instead imply that burrowing snakes (scolecophidians and anilioids) acquired their fossorial adaptations after the evolution of the snake body form and jaw apparatus in a large aquatic or (surface-active) terrestrial ancestor.

Self-assembly of the infectious bursal disease virus capsid protein, rVP2, expressed in insect cells and purification of immunogenic chimeric rVP2H particles by immobilized metal-ion affinity chromatography

A gene encoding a structural protein (VP2) of a local strain (P3009) of infectious bursal disease virus (IBDV) was cloned and expressed using the baculovirus expression system to develop a subunit vaccine against IBDV infection in Taiwan. The expressed rVP2 proteins formed particles of approximately 20-30 nm in diameter. Those particles were partially purified employing sucrose density gradient ultracentrifugation, and the purified particles were recognized by a monoclonal antibody against the VP2 protein of IBDV P3009. To facilitate the purification of the particles, the VP2 protein was engineered to incorporate a metal ion binding site (His)(6 )at its C-terminus. The chimeric rVP2H proteins also formed particles, which could be affinity-purified in one step with immobilized metal ions (Ni(2+)). Particle formation was confirmed by direct observation under the electron microscope. The production level of rVP2H protein was determined to be 20 mg/L in a batch culture of Hi-5 cells by quantifying the concentration of the purified proteins. The chicken protection assay was performed to evaluate the immunogenicity of the rVP2H protein. When susceptible chickens were inoculated with the recombinant rVP2H proteins (40 microg/bird), virus-neutralizing antibodies were induced, thereby conferring a high level of protection against the challenge of a very virulent strain of IBDV. In conclusion, the most significant finding in this work is that both of the expressed rVP2 and rVP2H proteins can form a particulate structure capable of inducing a strong immunological response in a vaccinated chicken.

Role of hsfA gene on host-specificity by Bradyrhizobium japonicum in a broad range of tropical legumes

Bradyrhizobium japonicum mutant strain NAD163, containing a 30-kb deletion mutant encompassing the hsfA gene, was inoculated onto a broad range of legume species to test host-specificity. Most legume species formed ineffective nodules except Vigna angularis var. Chibopat and Glycine max var. Pureunkong. A hsfA insertion mutant, BjjC211, gave similar results to strain NAD163, implying that many legume species require HsfA for host-specific nitrogen fixation. To determine whether other genes in the deleted region of NAD163 are also necessary, the hsfA gene was conjugally transferred into the NAD163 mutant. The transconjugant formed effective nodules on the host legume plants, which earlier had formed ineffective nodules with mutant NAD163. Thus, we conclude that the hsfA gene in the 30-kb region is the only factor responsible for host-specific nitrogen fixation in legume plants.