Detection of Mycobacterium tuberculosis in clinical specimens by polymerase chain reaction and Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test

The polymerase chain reaction (PCR) using oligonucleotides based on the repetitive sequence (IS986) of Mycobacterium tuberculosis as a primer and the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test (MTD), which combines an M. tuberculosis rRNA amplification method with the hybridization protection assay format, were evaluated for detection of M. tuberculosis in clinical samples. The detection limits of these two assay systems based on nucleic acid amplification for cultured M. tuberculosis were less than 10 cells per reaction. A total of 135 sputum specimens were examined by the two assay systems. The PCR and the MTD systems for detection of M. tuberculosis gave overall positivity rates of 84.2% (32 of 38) and 91.9% (34 of 37), respectively, as compared with 71.9% (23 of 32) by smear and 96.9% (31 of 32) by culture in the liquid medium MB-Check. Procedures for sample preparation used in the two methods were different. Although the sensitivities of the PCR and MTD appeared to be similar to that of culture with the MB-Check system, the two methods based on nucleic acid amplification should be very useful for rapid detection of M. tuberculosis infections without the long time required for culture of M. tuberculosis.

Evaluation of enteric coated tablet sensitive to pancreatic lipase. II. In vivo evaluation

Plain tablets containing a model drug, sulfamethizole (SMZ), were coated with triolein (TO), trilaurin (TL) and ethylcellulose (EC). The biological behavior of the coated tablets (TOTL-Tab), which are pH independent and sensitive to pancreatic lipase, was investigated in humans. Results of the administration of the tablets with or without an antacid, under fasting and non-fasting conditions, and at 0.5 h before and 0.5 h after meals, were examined. A comparison of the in vivo behavior of SMZ after the administration of these tablets was done using the following data: the lag time of urinary excretion (Ulag), the total urinary recovery percentage (X infinity u), and the mean residence time after Ulag (MRTaf). A typical pH-sensitive tablet coated by cellulose acetate phthalate (CAP-Tab) was used as a reference. For the administration of a CAP-Tab alone, the Ulag obtained under both the non-fasting and fasting condition was longer than that of the plain tablet. However, Ulag after the administration of a CAP-Tab with an antacid became considerably shorter. This lag time was about the same as that obtained from the plain tablet, regardless of food ingestion. The obtained CAP-Tab MRTaf and X infinity u values were not significantly different in comparison to the plain tablets. Under the non-fasting condition, Ulag, MRTaf and X infinity u of TOTL-Tab were not affected by the co-administration of an antacid, and these values were virtually the same as those obtained from a CAP-Tab without an antacid. The urinary excretion data obtained after the administration of TOTL-Tab alone under fasting was analogues to the non-fasting case.(ABSTRACT TRUNCATED AT 250 WORDS)

Pregnancy after chemotherapy for trophoblastic diseases and psychosomatic development in the progeny

We treated 542 patients with trophoblastic diseases from 1965 through 1988, and succeeded in preserving fertility in 269 of them (240 cases of invasive mole and 29 cases of choriocarcinoma). Of the 269 patients, 198 (79.5%) conceived after completing treatment. A total of 396 pregnancies in these women resulted in 295 term live births (74.5%), 51 spontaneous abortions (12.9%), and 4 recurrences of moles (1.0%). Four cases (1.32%) of malformations were discovered. The growth conditions of 101 children born in 1976 or later were followed up until the age of 18 months. Their heights or weights did not differ significantly from those of children measured in national infantile-growth surveys. The psychoneurological development of 54 children up to the age of 7 years who were studied by using infantile mental-development questionnaires showed no marked mental retardation. Our results provide strong evidence of the safety of chemotherapy for the treatment of trophoblastic diseases.

Increase in the amount of elongation factor 2 in rat liver by peroxisome proliferators

The changes in protein phosphorylation during induction and deinduction of peroxisome proliferation in rat liver by three types of proliferators were studied by in vitro phosphorylation assay. Among the variously phosphorylated proteins, an increase during induction and a decrease during deinduction in phosphorylation of P100, a cytosolic protein having a molecular weight of 100 kDa, was most remarkable. The time course of enhancement of phosphorylation by the administration of the proliferators, however, was not parallel with proliferation of peroxisome but with increase in the liver DNA content. Amino acid sequencing of the protein indicated the identity of its N-terminal 17 amino acid residues with those of elongation factor 2 (EF2). Increase in the amount of EF2 by peroxisome proliferators was confirmed by immunoblotting and this was almost parallel with peroxisome proliferation, suggesting that both increase in the amount of EF2 and some changes in phosphorylation activities account for a large increase in in vitro phosphorylation of EF2 by the administration of peroxisome proliferators.

Effect of hydrophilic and lipophilic vehicles on skin permeation of tegafur, alclofenac and ibuprofen with or without permeation enhancers

The effects of an ethanol/panasate 800 (tricaprylin) (40/60) system as a lipophilic vehicle, and an ethanol/water (60/40) system as a hydrophilic vehicle, with or without permeation enhancers for in vitro skin permeation and in vivo skin absorption of tegafur, alclofenac and ibuprofen with different lipophilicity, were evaluated. The in vitro and in vivo skin permeability of tegafur, alclofenac and ibuprofen was enhanced by the use of ethanol/panasate 800 (40/60) or ethanol/water (60/40) binary vehicles as a donor composition. However, the two vehicles showed contrastive properties in relation to the extent of permeation enhancement of the three drugs: tegafur > alclofenac > ibuprofen for the ethanol/panasate 800 (40/60) system, and ibuprofen > or = alclofenac > tegafur for the ethanol/water (60/40) system. When lauric acid, as a permeation enhancer, was added to both of the binary vehicles, the in vitro and in vivo skin permeability of three drugs further increased, and the in vivo absorption rate of the drugs from the ethanol/water (60/40) system was larger than that from the ethanol/panasate 800 (40/60) system. In conclusion, it was suggested that the ethanol/panasate 800 (40/60) lipophilic binary vehicle is useful for hydrophilic drugs, and conversely, the skin absorption of lipophilic drugs can be improved by the use of the ethanol/water (60/40) hydrophilic binary vehicle with or without lauric acid as a permeation enhancer.

Evidence that both cyclosporin and azathioprine prevent warm ischemia reperfusion injury to the rat liver

The present work was undertaken to study whether the immunosuppressive agents cyclosporin (CyA) and azathioprine (AZA) ameliorate hepatic injury after warm ischemia. A temporary, normothermic liver ischemia was induced in female Sprague-Dawley rats. The rats were treated with CyA (10 mg/kg per day p.o.), AZA (8 mg/kg per day p.o.), or vehicles for 4 days before surgery. Seven-day survival rates after 60 min of ischemia improved significantly with CyA (76.2%, P < 0.005) and AZA (78.6%, P < 0.001) treatment, compared with 43.0% for the control group. The highest levels of serum aminotransferases in the treatment groups tended to be lower than those in the control group. The peak values for the percentage of liver necrosis, an indicator of the extent of hepatic necrosis, in the animals treated with CyA (26.1% +/- 7.2%, mean +/- SEM) and AZA (32.1% +/- 5.7%) were significantly lower than in the control group (47.4% +/- 3.7%). Lipid peroxidative damage after reperfusion, assessed as the hepatic malondialdehyde (MDA) concentration, was significantly suppressed by pretreatment with CyA and AZA. Histological findings coincided with other parameters. This study demonstrates that both AZA and CyA have beneficial effects on normothermic liver ischemia in rats. It is suggested that the diminished lipid peroxidative damage with these agents might be one of the mechanisms responsible for this.

Coinduction of two low-molecular-weight stress proteins, alpha B crystallin and HSP28, by heat or arsenite stress in human glioma cells

The responses of two low-molecular-weight stress proteins, alpha B crystallin and HSP28, to various types of stress were determined quantitatively by specific immunoassays in a human glioblastoma cell line (U118 MG). Levels of alpha B crystallin (2-4 ng/mg protein) and HSP28 (1-1.5 micrograms/mg protein) in the soluble fraction from cells that had been cultured at 37 degrees C increased about 100-fold and 3-fold, respectively, within 24 h after heat treatment for 15 min at 45 degrees C, with a temporary decrease, due to redistribution to the insoluble fraction, during the heat treatment. Exposure of cells to arsenite (NaAsO2, 100 microM for 1 h) also induced the two proteins with a time course similar to that observed after heat stress, but without a decrease during the stress period. L-Azetidine-2-carboxylate (5 mM for 5 h) was also effective in inducing the two proteins, but to a lesser extent. Other chemicals, including CdCl2, ZnCl2, AlCl3, ethanol, caffeine, nicotine, NaN3, dibutyryl 3',5'-cyclic AMP, forskolin, and a phorbol ester, did not induce the two proteins. Expression of alpha B crystallin and HSP28 mRNAs in cells was enhanced after heat stress and after exposure to arsenite. When cells were challenged with heat stress in the presence of arsenite, the effect on the induction of the two proteins was synergistic. Ethanol (1-2%) enhanced the responses to heat stress or arsenite stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological modulation of antigen-induced airway hyperresponsiveness by thromboxane A2 inhibitors in guinea pigs

The effects of OKY-046 (thromboxane A2 (TXA2) synthetase inhibitor) and ONO-3708 (TXA2 receptor antagonist) on antigen-induced airway hyperreactivity in guinea pigs were investigated. Ketotifen was used as a reference drug. Seven inhalations of an antigen into actively sensitized animals resulted in an increase in airway reactivity to acetylcholine. Twenty-four hours after the final inhalation, the number of leukocytes (macrophages, neutrophils, eosinophils and lymphocytes) and the quantity of mediators (thromboxane B2, leukotriene D4 and histamine) in bronchoalveolar lavage fluid increased. All examined drugs inhibited the antigen-induced airway hyperreactivity to acetylcholine. Whereas ketotifen inhibited an accumulation of inflammatory cells (eosinophils and neutrophils) in bronchoalveolar lavage fluid, OKY-046 and ONO-3708 had no effect on the accumulation of inflammatory cells. OKY-046, but not ketotifen and ONO-3708, inhibited an increase of thromboxane B2 in the bronchoalveolar lavage fluid after antigen provocation. These results suggest the participation of TXA2 in the onset of antigen-induced airway hyperresponsiveness in guinea pigs, and the efficacy of TXA2 inhibitors, without affecting the accumulation of inflammatory cells in bronchoalveolar lavage fluid.

Alpha B crystallin and HSP28 are enhanced in the cerebral cortex of patients with Alzheimer's disease

The localization of two small heat shock proteins, alpha B crystallin and 28-kDa heat shock protein (HSP28), was studied immunochemically and immunohistochemically in cerebral cortex of patients with Alzheimer's disease (AD) and control groups. By specific immunoassays for alpha B crystallin and HSP28, we found that the concentrations of alpha B crystallin are elevated in the temporal and frontal lobes, while those of HSP28 are elevated in the temporal, frontal, and parietal lobes in the AD brains. Immunohistochemically, alpha B crystallin was localized in astrocytes and oligodendrocytes, while HSP28 was present in degenerating neurons in the cerebral cortex of both AD and control brains. However, alpha B crystallin-immunoreactive astrocytes and HSP28-immunoreactive degenerating neurons were more frequently observed in AD brains. The immunoreactivity for HSP28 was also found in the senile plaques in the AD brains. These findings suggest that the increased accumulations of these small heat shock proteins appear to be part of reactive processes of glial cells and neurons under pathologic conditions.

Immunocytochemical localization of calcineurin in the adult and developing primary visual cortex of cats

An immunocytochemical method was used to localize calcineurin, a calcium-dependent calmodulin-stimulated protein phosphatase, in the primary visual cortex of developing and adult cats. In the adult calcineurin immunoreactivity exhibits a laminar distribution with dense labeling in the upper half of layers II/III and two lightly labeled bands in lower layer IV and in layer VI. Most of the immunoreactive neurons are pyramidal in shape and appear to form a subpopulation of cortical neurons, but non-pyramidal neurons were also labeled, especially during early stages of postnatal development. The distribution pattern of calcineurin immunoreactivity showed developmental changes until at least 3 months of age. The number of calcineurin-positive cells abruptly increased at 3 weeks, and heavily labeled neurons appeared in a well-delineated band in layer IV between 3 and 5 weeks of age. At 6 to 10 weeks, neurons in layers II/III also became strongly immunoreactive. At this developmental stage intensely stained cells were thus distributed throughout layers II to IV. Thereafter, there was a marked decrease in the number of immunoreactive cells in layer IV and beyond 12 weeks the distribution pattern of calcineurin immunoreactivity became similar to that of adult animals. These changes of calcineurin expression show some relation with the inside-out pattern of cortical maturation and with the time course and the laminar selectivity of use-dependent malleability. Therefore, we suggest that calcineurin may be involved in processes of neuronal differentiation and experience-dependent plasticity.

Skin permeation enhancement of tegafur by ethanol/panasate 800 or ethanol/water binary vehicle and combined effect of fatty acids and fatty alcohols

The effects of vehicle and enhancer on the skin permeation of tegafur across excised hairless mouse skin were investigated. Ethanol, water, panasate 800 (tricaprylin), and their mixtures were used as vehicles, and then a series of fatty acids or fatty alcohols was employed as representative enhancers. The skin permeability of tegafur was dramatically increased by the combination of ethanol and panasate 800, whereas the combination of ethanol and water resulted in only a little increase. The greatest permeation ratio (56.8% of dose at 12 h) was obtained with the ethanol/panasate 800 (40/60) binary vehicle. Furthermore, the skin permeability of tegafur could be enhanced by the addition of fatty acids or fatty alcohols to ethanol/panasate 800 (40/60) and ethanol/water (60/40) binary vehicles. The infinite dose studies suggested that panasate 800 decreased the lag time by increasing the diffusion of tegafur, and ethanol increased the permeation rate by increasing the partition of tegafur into skin. The effects of fatty acids or fatty alcohols added to ethanol as a single vehicle were dramatic, but did not appear in the case of panasate 800 as a single vehicle. In conclusion, panasate 800 was an excellent hydrophobic vehicle in that it minimized time lag and promoted tegafur permeability combined with ethanol. This improvement was further promoted when enhancers were added.

[Sinus thrombosis during CDDP and VP-16 (PE) therapy for suprasellar germ-cell tumor: case report]

A case of sinus thrombosis occurring during combination chemotherapy with CDDP and VP-16 (PE) for a suprasellar germ-cell tumor is presented. A 5-year-old girl developed polyuria, polydipsia and headache in April, 1991 and became unconscious on May 10, 1991, when MRI and CT demonstrated a suprasellar tumor and marked hydrocephalus. After a ventriculo-peritoneal shunt operation, radiotherapy and two courses of PE therapy were carried out. During the second course of PE therapy, diabetes insipidus became quite difficult to control and severe hypovolemic hypernatremia developed. While it was being treated, the patient developed a clonic convulsion of her left extremities and visual disturbance. CT scan demonstrated a right parietal hemorrhagic infarction and IV-DSA suggested thrombosis of the superior sagittal sinus. Laboratory data disclosed DIC. The main cause of sinus thrombosis in this patient was considered severe dehydration. It is also possible that cisplatin and steroid played a role. In addition to these, dysfunction of hypothalamus, which is one of the regulatory centers of the plasma concentration of factor VIII, may have contributed to the acceleration of blood coagulation. This case re-emphasized the importance of preventing dehydration and monitoring the blood coagulation fibrinolytic system during PE therapy in patients with a suprasellar germ-cell tumor accompanied with diabetes insipidus.

[Intraocular lens implantation in severely mentally and physically handicapped patients]

We implanted a posterior chamber intraocular lens (PC-IOL) in 30 eyes of 17 severely mentally and physically handicapped patients, i.e., 14 eyes of 9 severely mentally retarded patients, 14 eyes of 7 patients with Down's syndrome, and 2 eyes of a mitochondrial encephalomyopathy patient. All surgery was performed under general anesthesia and 3 to 10 post-operative days of hospital care were needed in an ophthalmic ward. A post-operative intensive care unit was not necessary. Severe post-operative complications occurred in 2 eyes of 2 cases. One case was complicated by an iris prolapse, and in another case traumatic wound rupture caused a prolapse of the IOL, vitreous, and retina. However, in both cases, the other eye, which also had a PC-IOL implantation, showed an uneventful post-operative course. Vision and quality of life in all patients seem to have improved. The present observations indicate that cataract surgery with PC-IOL for these patients should be positively considered in spite of difficulties in pre- and post-operative management, and when done, calibration of IOL power immediately before surgery under general anesthesia and small incision techniques are essential.

Neuronal induction of 72-kDa heat shock protein following methamphetamine-induced hyperthermia in the mouse hippocampus

By means of an immunohistochemical technique, we examined the neuronal induction of 72-kDa heat shock protein (HSP72) in response to methamphetamine-induced hyperthermia in the mouse hippocampus. Strong HSP72 immunoreactivity (ir) was found in the neurons of hippocampus proper, particularly in the CA1/2 and medical CA3 subfields, at 10 h after drug injection. By 18 h, those neurons still revealed HSP72-ir, while neurons of the dentate gyrus also appeared positive for HSP72. At this stage, intense HSP72-ir was first detected in non-neuronal cells, i.e. glial and vascular endothelial cells. At 24 h, no apparent HSP72-ir was found in the hippocampal neurons, while only non-neuronal cells still revealed immunoreactivity for HSP72. In addition, no morphological evidence of cell degeneration or loss was noted in the CA1 sector or other hippocampal regions at 5 days after hyperthermic insult. In conclusion, (1) methamphetamine-induced hyperthermia per se is a stressful stimulant causing neuronal induction of HSP72 in the hippocampus neurons, particularly of CA1/2 and medial CA3 sectors, but does not prove fatal to the cells; (2) there is a cell type-specific difference in response to hyperthermic insult by inducing HSP72 and the timing of the induction response in the hippocampal formation; and (3) the animals that underwent drug-induced hyperthermia may be useful as an experimental model for the study of the protective mechanism of heat shock proteins against subsequent harmful stimuli.

Anterior surgery in four consecutive technical phases for cervical spondylotic myelopathy

Between 1960 and 1990, 175 patients having anterior operations for cervical spondylotic myelopathy were evaluated during the course of four operative phases. Specific attention was paid to spine and spinal cord morphologic changes occurring in 52 patients, who were followed up for more than 12 years. Although overall outcomes were satisfactory, a disturbing incidence of neurologic deterioration caused by spondylolisthesis at levels adjacent to fused segments, kyphosis, and altered cord morphology was noted 10 years after surgery. These changes, observed in patients with multilevel pathology and a narrowed spinal canal, promoted the adoption of more stringent operative criteria, including ultrasonically confirmed 16-mm or greater anterior trough decompressions and the performance of long fusions with vascularized fibular struts.

Dissecting aneurysm of the posterior inferior cerebellar artery: case report

A patient with a dissecting aneurysm of a posterior inferior cerebellar artery who presented with Wallenberg's syndrome is reported. A 31-year-old man suddenly experienced an occipital headache, vertigo, and vomiting, followed by dysphagia. A neurological examination revealed partial Wallenberg's syndrome. Vertebral angiography revealed aneurysmal dilatation at the origin of the left posterior inferior cerebellar artery, with distal luminal narrowing. T1-weighted magnetic resonance imaging demonstrated an area of high-signal intensity, indicating an intramural hemorrhage in the arterial wall of the narrowed lumen. The dissecting aneurysm with a typical intramural hematoma of the posterior inferior cerebellar artery was entrapped with clips after an anastomosis of the left occipital artery to the distal posterior inferior cerebellar artery. The diagnosis and the treatment of dissecting aneurysms of the posterior inferior cerebellar artery are discussed.

[Post operative embolism and left atrial enlargement in the old-aged ASD (atrial septal defect) patients]

As the operation risk of ASD is little today, the unexpected postoperative complication such as embolism is a miserable concern. We experienced two cases of embolism, which were cerebral infarction, in old-aged patients after ASD correction. It has been reported that low cardiac function, atrial fibrillation and foreign body in the left atrium should be risk factors of the embolism after ASD correction. However, blood stasis in the left atrium due to its enlargement may be an essential risk factor of the embolism. Accordingly we evaluated the left atrial volume in 87 ASD patients without complicated cardiac disorder. There was a significant correlation between the age (X) and left atrial volume index (Y). (Y = 16.5 + 1.1X, r = 0.668, p < 0.001). Left atrial volume index in our two cases of cerebral infarction indicated 171.7, 190.8 ml/m2 respectively. The former case had sinus rhythm and its defect was directly closed, and the latter had atrial fibrillation and its defect was closed with teflon patch. In addition pulmonary artery pressure and cardiothoracic ratio correlated with left atrial volume index significantly. Although some investigators reported that pulmonary hypertension and cardiomegaly were the risk factors of embolism, the left atrial enlargement by aging was thought to be the main risk factor. Thus, we concluded that anticoagulant therapy was necessary for the ASD patients with marked left atrial enlargement.

Identification of the pregnancy responsible for gestational trophoblastic disease by DNA analysis

In three cases of choriocarcinoma, genetic loci including a variable number of tandem repeat regions were amplified by the polymerase chain reaction method on DNA from three established cell lines and from lymphocytes of patients and their husbands to identify the responsible pregnancy. Case 1, from whom NaUCC-3 was derived, had only one full-term fetal death. Case 2, from whom NaUCC-4 was derived, had one normal delivery followed by one complete molar delivery and one normal delivery. Case 3, from whom NaUCC-2 was derived, had one normal delivery followed by one complete molar delivery. In case 1, NaUCC-3 was found to be of parental origin and derived from the pregnancy with full-term fetal death. In cases 2 and 3, NaUCC-4 and NaUCC-2 were of probable androgenetic origin and were derived from the pregnancy with complete hydatidiform mole. We also conducted the restriction fragment length polymorphism method using case 1 samples, and it confirmed the results based on the polymerase chain reaction method product patterns. All nine cases of hydatidiform mole and three cases of invasive mole were of androgenetic origin. The polymerase chain reaction method thus makes it possible to identify easily the pregnancy responsible for choriocarcinoma using only a few specimens without isotopes.

Possible action of human placental aminopeptidase N in feto-placental unit

Aminopeptidase N purified from human placenta actively hydrolyzed various immunomodulating peptides from their N-terminus such as splenopentin, thymopentin, thymic humoral factor gamma 2, tuftsin and rigin in vitro. Aminopeptidase N also actively hydrolyzed neuropeptide hormones (met-enkephalin, somatostatin and neurokinin A) and vasoactive peptides (lysyl-bradykinin and angiotensin III) from their N-terminus. In addition, angiotensin II, secretin, thymopoietin II peptide fragment, motilin, endothelin-I and insulin were tested for hydrolysis by aminopeptidase N. Km and Vmax values for the N-terminal amino acid, Thr, a liberation from tuftsin were 267 microM and 8.33 mumol/min/mg protein, respectively. L-Leucyl-p-nitroanilidase activity in the human placental membrane fraction was almost completely neutralized by anti-aminopeptidase N antibody. Our present study suggests that possible roles for surface enzyme aminopeptidase N in the human placenta would be to down-regulate the action of immunomodulating peptides as well as vasoactive and neuropeptide hormones, and to control both immunology and endocrinology of pregnancy.

The effect of a prostaglandin I2 analogue (OP-41483) on energy metabolism in liver preservation and its relation to lipid peroxidative reperfusion injury in rats

The effect of the stable prostacyclin (PGI2) analogue OP-41483 (OP) on liver preservation was investigated in the rat liver transplant model. In a 1-week survival study, 33 orthotopic liver transplants were performed using Wistar rats. In group A, untreated livers were stored with modified UW (mUW) solution at 4 degrees C. In group B, livers from OP-pretreated donors (2 micrograms/kg, i.v.) were stored with mUW solution containing OP (1 microgram/ml) at 4 degrees C. After 24 h storage, the donor grafts in each group were transplanted to untreated recipients. OP treatment (group B) significantly improved 1-week survival (62.5%, 10/16, P < 0.01 versus group A; 11.8%, 2/17). For the measurement of adenine nucleotides and lipid peroxidation (malondialdehyde, MDA) in liver tissue before preservation, after preservation, and 3 h after transplantation, 20 rat livers in groups A and B were studied. In both groups, the levels of adenosine triphosphate (ATP) declined 6 h after cold preservation, but this degradation of ATP was significantly halted at the level of adenosine monophosphate (AMP) in the OP-treated livers after 24 h of storage. However, OP treatment showed no significant difference in the degree of ATP recovery after transplantation. On the other hand, OP treatment resulted in suppression of the increase in MDA levels and histological amelioration of microcirculatory disturbance 3 h after transplantation. Our data suggested that the combined use of the stable PGI2 analog (OP-41483) and UW solution is beneficial in liver preservation.(ABSTRACT TRUNCATED AT 250 WORDS)