A further discussion on the peculiarity of maximum entropy image deconvolution in HREM

Some important features observed in the maximum entropy image deconvolution in HREM were studied and demonstrated as a supplement to previous publications in Ultramicroscopy 35 (1991) 339 and 62 (1996) 141. It has been shown that in the process of image deconvolution how the errors of assigned electron-optical parameters can be compensated and the effect of crystal thickness can be corrected. The 'negative-potential problem' has been solved more perfectly than before via the normalization of sum total entropy.

Risk factors of adverse drug reaction caused by nimesulide in Shanghai patients with osteoarthropathy

The aim of this study was to investigate the risk factors for adverse drug reactions (ADRs) to nimesulide in patients from Shanghai with osteoarthropathy. A retrospective epidemiological study was performed to obtain information (observational variables) on demographics, primary disease, family history of disease, quality of life, dietary habits, lifestyle, use of nonsteroidal anti-inflammatory drugs (NSAIDs) and ADR history of NSAIDs. Univariate and multivariate analyses were performed to establish the relationship between these observational variables and the occurrence of ADRs caused by nimesulide. Among the 726 variables, five risk factors for ADRs to nimesulide were identified. The study showed an increased risk for ADR occurrence with increased scoring of the following four factors: (i) "Concomitant drug therapy" (odds ratio [OR]: 4.66, 95% confidence intervals [CI]: 1.26-17.26, p < 0.05); (ii) "Compared with six months ago, how would you rate your health in general now?" (OR: 1.38, 95% CI: 1.03-1.84, p < 0.05); (iii) "General feeling of health status" (OR: 1.27, 95% CI: 1.03-1.56, p < 0.05) and (iv) "1 expect my health to get worse" (OR: 2.05, 95% CI: 1.22-3.44, p < 0.01). There was a decreased risk for ADR occurrence with increased scoring of the factor "Have you ever suffered from depression that impacted on your life?" (OR: 0.15, 95% CI: 0.03-0.66, p < 0.05). The predictive model for the overall incidence rate of ADRs caused by nimesulide was then established. In conclusion, the predictive model helps to indicate the risk of ADRs to nimesulide and provides clinicians with an alternative method for decision making when prescribing this drug.

[Pulse oximetry screening for sleep-disordered breathing in stroke]

BACKGROUND

The prevalence of sleep-disordered breathing, particularly obstructive sleep apnea, among stroke patients is high. Routine screening with the current diagnostic gold standard of polysomnography is not feasible. Pulse oximetry could be a simple screening test.

METHODS

The signal of pulse oximetry, recorded during full polysomnography in 184 stroke patients during neurological rehabilitation, was analyzed automatically by software for desaturations >/= 4 %. The polysomnographic apnoea-hypopnoea-index (AHI) was used as the diagnostic gold standard and compared with the oxygen desaturation index (ODI).

RESULTS

Correlation between AHI of PSG and ODI of oximetry was r = 0.84 (p < 0.001). Dependent on the definition of SDB (AHI 10, 15, 20 or 30/h) and the cut-off-point for the ODI (e. g. 15/h) sensitivity was 32 - 83 % and specificity 99 - 96 %. The diagnostic accuracy as determined by the area under the ROC-curve was 96 %.

CONCLUSION

Automated analysis of pulse oximetry gives reasonable results for screening for SDB in stroke patients and could be used in populations with high pre-test probability.

Regeneration of plants from callus tissues of hairy roots induced by Agrobacterium rhizogenes on Alhagi pseudoalhagi

The legume forage Alhagi pseudoalhagi was transformed by the Agrobacterium rhizogenes strain A4 using cotyledon and hypocotyl segments as infection materials. Regenerated plants were achieved from sterile calli derived from hairy roots, which occurred at or near the infection sites. The regenerated plants from hairy root were characterized by normal leaf morphology and stem growth but a shallow and more extensive root system than normal plants. Opine synthesis, PCR and Southern blot confirmed that T-DNA had been integrated into the A. pseudoalhagi genome. Acetosyringone (AS) was found to be vital for successful transformation of A. pseudoalhagi.

Role of reactive oxygen intermediates in Japanese encephalitis virus infection in murine neuroblastoma cells

Infection with Japanese encephalitis virus (JEV), a mosquito-borne, neurotropic flavivirus, may cause acute encephalitis in humans and induce severe cytopathic effects in various types of cultured cells. This study attempted to determine whether JEV infection induces free radical generation and whether oxidative stress contributes to virus-induced cell death in neuroblastoma cells. A rise in the intracellular level of free radicals indicated by the 2',7'-dichlorofluorescein fluorescence was observed in N18 cells following JEV infection. Cellular flavon-containing enzymes were involved in JEV-induced fluorescent change. Cells were moderately protected from JEV-induced death by diphenyleneiodonium, a flavon-containing enzyme inhibitor, whereas common antioxidants such as N-acetylcysteine, pyrrolidine dithiocarbamate, Tiron, and Trolox turned out to be ineffective. These results suggest that the direct antioxidant action is not helpful in prevention of JEV-induced neuronal cell death.

Stabilization of an elevated heavy metal contaminated site

Heavy metal contamination is a common problem that is encountered at many uncontrolled sites. Immobilization is seen as a promising technology for heavy metal remediation. Here, we report a remediation case study of an elevated and multi-metal contaminated site containing Cd, Cu, Ni, Pb, and Zn. In a laboratory test, when the soil was stabilized with reagent grade stabilizers (CaHPO(4) and CaCO(3)), the toxicity characteristic leaching procedure (TCLP) extractable concentrations of Cd, Cu, Pb, and Zn were reduced by more than 87%. The greatest reduction was shown with Pb (99.8%). In the field, Ca(H(2)PO(4))(2) due to lower cost and higher solubility replaced CaHPO(4). The TCLP results of the field treatment showed that the extractable concentrations of Cd, Cu, Pb, and Zn were significantly reduced after 30 days of stabilization. The reduction ratios were 98% (Cd), 97% (Cu), 99% (Pb), and 96% (Zn). Although, the reduction ratio of Ni was only 65%, the average extractable concentration was still less than 4.0mg/l. The percent reduction can, therefore, be considered reasonable. The significant reduction of extractable metal concentrations showed that the stabilizers, a combination of Ca(H(2)PO(4))(2) and CaCO(3), successfully immobilized heavy metals on the site.

Rapidly progressive interstitial renal fibrosis associated with Chinese herbal medications

BACKGROUND/AIM

Nephropathy after ingestion of Chinese herbs is known as a rapidly progressive form of interstitial renal fibrosis after a slimming regimen containing aristolochic acid that was identified first in Belgium. Intake of traditional Chinese herbal medicines is very popular in Taiwan. So we looked for similar cases in our hospital.

METHODS

From 1994 to 1998, we observed 20 Taiwanese patients who underwent renal biopsy for rapidly progressive renal failure of unknown origin. The medical history of these patients gave no clue to the origin of renal impairment, except for the administration of Chinese herbs before the development of renal failure in all cases.

RESULTS

Although these patients took herbal medications from various sources for different purposes, their renal biopsy specimens showed strikingly similar histological patterns: extensive paucicellular interstitial fibrosis and tubular atrophy, but the glomeruli were apparently intact. They also had similar clinical features, such as a nearly normal blood pressure, obvious anemia, insignificant edema, low-grade proteinuria, and glucosuria. The renal function declined rapidly in most cases; 15 patients underwent dialysis within 3 months of renal biopsy, and 7 patients received emergency dialysis when they first came to our hospital. On clinical and morphological grounds, the nephropathy in our patients appears similar to Chinese herb nephropathy.

CONCLUSIONS

Because of the diversity of the herbal regimens used, in addition to aristolochic acid, other unidentified phytotoxins may also play a role in this particular disease entity. There is a strong relation between rapidly progressive interstitial renal fibrosis and the consumption of Chinese herbs.

Purification, sequencing, and phylogenetic analyses of novel Lys-49 phospholipases A(2) from the venoms of rattlesnakes and other pit vipers

Basic phospholipase A(2) homologs with Lys49 substitution at the essential Ca(2+)-binding site are present in the venom of pit vipers under many genera. However, they have not been found in rattlesnake venoms before. We have now screened for this protein in the venom of rattlesnakes and other less studied pit vipers. By gel filtration chromatography and RP-HPLC, Lys49-phospholipase-like proteins were purified from the venoms of two rattlers, Crotalus atrox and Crotalus m. molossus, and five nonrattlers, Porthidium nummifer, Porthidium godmani, Bothriechis schlegelii, Trimeresurus puniceus, and Trimeresurus albolabris. Their N-terminal amino acid sequences were shown to be characteristic for this phospholipase subfamily. The purified basic proteins from rattlesnakes caused myonecrosis and edema in experimental animals. We have also cloned the cDNAs and solved the complete sequences of four novel Lys49-phospholipases from the venom glands of C. atrox, P. godmani, B. schlegelii, and Deinagkistrodon acutus (hundred-pace). Phylogenetic analyses based on the amino acid sequences of 28 Lys49-phospholipases separate the pitviper of the New World from those of the Old World, and the arboreal Asiatic species from the terrestrial Asiatic species. The implications of the phylogeny tree to the systematics of pit vipers, and structure-function relationship of the Lys49-phospholipases are discussed.

Signaling pathway mediated by kappa-opioid receptor is impaired in cardiac hypertrophy

AIM

The responses of the intracellular calcium ([Ca2+]i) and the intracellular pH (pHi) to kappa-opioid receptor stimulation were determined in the single right ventricular myocytes isolated from the hearts of chronically hypoxic rats which exhibited right ventricular hypertrophy (RVH).

METHODS

With the spectrofluorometric method, the electrically-induced [Ca2+]i transient and pHi were measured in myocytes loaded with fura-2 and BCECF [2',7'-bis-(2-carboxyethyl)-5-(and 6)-carboxyfluorscein], respectively.

RESULTS

U50,488H, a selective kappa-opioid agonist decreased the electrically-induced [Ca2+]i transient and increased the pHi. The effect of U50,488H was mediated by protein kinase C (PKC). In the RVH, the effect of U50,488H on the [Ca2+]i transient and the pHi were significantly attenuated. In parallel, 4-phorbol 12-myristate 13-acetate (PMA), an activator of PKC, also decreased the [Ca2+]i transient and increased the pHi. In the RVH, the effects of PMA were blunted. The recovery of pHi, which was blocked by ethylisopropyl-amiloride (EIPA), following an acid loading induced by washout of 10 mmol/L NH4)Cl exposing to the cells for 10 min was the same in the RVH and control myocytes.

CONCLUSION

kappa-Opioid receptor signaling was impaired in the cardiac hypertrophy due to a defect in the coupling of PKC signaling with its effector.

Treatment of obstructive sleep apnoea with nasal continuous positive airway pressure in stroke

The prevalence of obstructive sleep apnoea (OSA) following stroke is high and OSA is associated with increased morbidity, mortality and poor functional outcome. Nasal continuous positive airway pressure (nCPAP) is the treatment of choice for OSA, but its effects in stroke patients are unknown. The effectiveness and acceptance of treatment with nCPAP in 105 stroke patients with OSA, admitted to rehabilitation was prospectively investigated. Subjective wellbeing was measured with a visual analogue scale in 41 patients and 24-h blood pressure was determined in 16 patients before and after 10 days of treatment. Differences were compared between patients who did and did not accept treatment. There was an 80% reduction of respiratory events with concomitant increase in oxygen saturation and improvement in sleep architecture. No serious side-effects were noticed. Seventy-four patients (70.5%) continued treatment at home. Nonacceptance was associated with a lower functional status, as measured by the Barthel Index, and the presence of aphasia. Ten days after initiation of nCPAP, compliant users showed a clear improvement in wellbeing (differences in visual analogue scale (deltaVAS) mean+/-SD 26+/-26 mm) versus noncompliant patients (deltaVAS 2+/-25 mm, p=0.021). Only the compliant group had a reduction in mean nocturnal blood pressure (deltaBP; -8+/-7.3 mmHg versus 0.8+/-8.4 mmHg, p=0.037). Stroke patients with obstructive sleep apnoea can be treated effectively with nasal continuous positive airway pressure and show a similar improvement and primary acceptance to obstructive sleep apnoea patients without stroke. Continuous positive airway pressure acceptance is associated with improved wellbeing and decreased nocturnal blood pressure.

Isolation of a choline monooxygenase cDNA clone from Amaranthus tricolor and its expressions under stress conditions

Plants synthesize the osmoprotectant glycine betaine (GB) via choline-->betaine aldehyde-->glycine betaine[1]. Two enzymes are involved in the pathway, choline monooxygenase (CMO) and betaine aldehyde dehydrogenase (BADH). A full length CMO cDNA (1,643bp) was cloned from Amaranthus tricolor. The open reading frame encoded a 442-amino acid polypeptide, which showed 69% identity with CMOs in Spinacia oleracea L. and Beta vulgaris L. DNA gel blot analysis indicated the presence of one copy of CMO gene in the A. tricolor genome. The expressions of CMO and BADH proteins in A.tricolor leaves significantly increased under salinization, drought and heat stress (42 degrees C), as determined by immunoblot analysis, but did not respond to cold stress (4 degrees C), or exogenous ABA application. The increase of GB content in leaves was parallel to CMO and BADH contents.

Adaptive pressure support servo-ventilation: a novel treatment for Cheyne-Stokes respiration in heart failure

Adaptive servo-ventilation (ASV) is a novel method of ventilatory support designed for Cheyne-Stokes respiration (CSR) in heart failure. The aim of our study was to compare the effect of one night of ASV on sleep and breathing with the effect of other treatments. Fourteen subjects with stable cardiac failure and receiving optimal medical treatment were tested untreated and on four treatment nights in random order: nasal oxygen (2 L/min), continuous positive airway pressure (CPAP) (mean 9.25 cm H(2)O), bilevel (mean 13.5/5.2 cm H(2)O), or ASV largely at the default settings (mean pressure 7 to 9 cm H(2)O) during polysomnography. Thermistor apnea + hypopnea index (AHI) declined from 44.5 +/- 3.4/h (SEM) untreated to 28.2 +/- 3.4/h oxygen and 26.8 +/- 4.6/h CPAP (both p < 0.001 versus control), 14.8 +/- 2.3/h bilevel, and 6.3 +/- 0.9/h ASV (p < 0.001 versus bilevel). Effort band AHI behaved similarly. Arousal index decreased from 65.1 +/- 3.9/h untreated to 29.8 +/- 2.8/h oxygen and 29.9 +/- 3.2/h CPAP, to 16.0 +/- 1.3/h bilevel and 14.7 +/- 1.8/h ASV (p < 0.01 versus all except bilevel). There were large increases in slow-wave and rapid eye movement (REM) sleep with ASV but not with oxygen or CPAP. All subjects preferred ASV to CPAP. One night ASV suppresses central sleep apnea and/or CSR (CSA/CSR) in heart failure and improves sleep quality better than CPAP or 2 L/min oxygen.

Phase I and pharmacokinetic study of the novel MDR1 and MRP1 inhibitor biricodar administered alone and in combination with doxorubicin

PURPOSE

To evaluate the safety, tolerability, and pharmacokinetics of biricodar (VX-710), an inhibitor of P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP1), alone and with doxorubicin in patients with advanced malignancies. The effect of VX-710 on the tissue distribution of (99m)Tc-sestamibi, a P-gp and MRP1 substrate, was also evaluated.

PATIENTS AND METHODS

Patients with solid malignancies refractory to standard therapy first received a 96-hour infusion of VX-710 alone at 20 to 160 mg/m(2)/h. After a 3-day washout, a second infusion of VX-710 was begun, on the second day of which doxorubicin 45 mg/m(2) was administered. Cycles were repeated every 21 to 28 days. (99m)Tc-sestamibi scans were performed before and during administration of VX-710 alone.

RESULTS

Of the 28 patients who enrolled, 25 patients were eligible for analysis. No dose-limiting toxicity (DLT) was observed in the nine assessable patients who received 120 mg/m(2)/h or less. Among seven patients receiving VX-710 160 mg/m(2)/h, two DLTs were seen: reversible CNS toxicity and febrile neutropenia. All other adverse events were mild to moderate and reversible. Plasma concentrations of VX-710 in patients who received at 120 and 160 mg/m(2)/h were two- to fourfold higher than concentrations required to fully reverse drug resistance in vitro. VX-710 exhibited linear pharmacokinetics with a harmonic mean half-life of 1.1 hours. VX-710 enhanced hepatic uptake and retention of (99m)Tc-sestamibi in all patients.

CONCLUSION

A 96-hour infusion of VX-710 at 120 mg/m(2)/h plus doxorubicin 45 mg/m(2) has acceptable toxicity in patients with refractory malignancies. The safety and pharmacokinetics of VX-710 plus doxorubicin warrant efficacy trials in malignancies expressing P-gp and/or MRP1.

[Process analysis of cognitive-behavioral group psychotherapy for patients with panic disorder]

The study explores the verbal interaction relationship between therapists and members, and the interaction model of this group. Six subjects were chosen by convenience sampling from the psychiatric OPD of a medical center in the Taichung area. Subjects with informed consent participated in a 12-week course of closed group psychotherapy. All data was tape-recorded and the Hill Interaction Matrix (HIM) scale was applied for simultaneous triangulation, in order to analyze the group's dynamic development of cognitive-behavioral psychotherapy for patients with panic disorder. The results indicated that the interactive relationship between therapists and members fluctuated during the group process. Development of the group process can be subdivided into three stages: initial stage-adaptive and familiar, middle stage-explorative, and terminal stage-productive. The amount of verbal interaction was greatest in the third quadrant. In the group interaction model, the therapist tended to explore the members' problems most. Providing support was the second most frequent. Meanwhile, members also tended to discuss personal problems. It was revealed that the verbal interaction of the therapists and members were the same. The content style of this group session is member-centered, and work style is pre-worked. The results showed that the group sessions did have great therapeutic value for members.

[The vasodilation and its mechanism of C-type natriuretic peptide]

AIM AND METHODS

With routine blood vessel perfusion in vitro, the vasodilation and its mechanism of C-type natriuretic peptide, a new member of natriuretic peptide family were observed in rabbits.

RESULTS

CNP had the dose-dependent vasodilation effects on abdominal artery and celiac vein at the range of 10(-10)-10(-6) mol/L, its action on vein was just like nitroglycerin, its action on artery was weaker than that of ANP. Atropine (10(-7) mol/L), Regitine (20 microg), and indomethacin (20 microg) had nothing effect on the vasodilation of CNP on abdominal artery. But glibenclamide (10(-6) mol/L) and propranolol (10(-6) mol/L) could decrease the vasodilation of CNP obviously, in addition, CNP couldn't inhibit the vasoconstriction of NE.

CONCLUSION

(1) CNP might be kind of venous systemic vasodilator, and it was also a arterial selective peptide controlling the vessel tone. (2) CNP dilated the vessel at least through two ways: (a) ATP-sensitive K+ channel, (b) beta-receptor.

Recombinant adenovirus expressing adeno-associated virus cap and rep proteins supports production of high-titer recombinant adeno-associated virus

It has been difficult to produce a chimeric vector containing both Ad and AAV rep and cap, and to grow such chimeric vectors in 293 cells. By recombination in vitro in a bacterial host, we were able to produce recombinant plasmid AdAAV (pAdAAVrep-cap), which could be used to generate recombinant AdAAV (rAdAAVrep-cap) after transfection into 293 cells. A recombinant adenovirus, rAdAAVGFP, in which the green fluorescent protein (GFP) gene is flanked by the AAV terminal repeats cloned into the E1-deleted site of Ad was also generated. Co-infection of rAdAAVrep-cap together with rAdAAVGFP into 293 cells resulted in production of high titers of rAAV expressing GFP. It was noted that the titer of rAdAAVrep-cap was lower than the titer of control AdCMVLacZ. The lower titer of rAdAAvrep-cap was associated with expression of Rep protein. Non-homologous recombination occurs after high passage and results in deletions within the AAV rep genes. These results indicate that (1) rAdAAVrep-cap can be produced; (2) rAdAAVrep-cap + rAdAAVGFP is a convenient and efficient way to transfect 293 cells to grow high titer rAAV; and (3) frozen stock is required to avoid propagation of rep-deleted pAdAAVrep-cap.

New vortex-matter size effect observed in Bi(2)Sr(2)CaCu(2)O(8 + delta)

The vortex-matter 3D to 2D phase transition is studied in micron-sized Bi(2)Sr(2)CaCu(2)O(8 + delta) single crystals using local Hall magnetization measurements. At a given temperature, the second magnetization peak, the signature of a possible 3D--2D vortex phase transition, disappears for samples smaller than a critical length. We suggest that this critical length should be equated with the 2D vortex lattice ab-plane correlation length R(2D)(c). The magnitude and temperature dependence of R(2D)(c) agree well with Larkin-Ovchinnikov collective pinning theory.

Differential Expression and Geographic Variation of the Venom Phospholipases A2 of Calloselasma rhodostoma and Trimeresurus mucrosquamatus

To investigate the geographic variations in venoms of two medically important pitvipers, we have purified and characterized the phospholipases A2 (PLA2s) from the pooled venoms of Calloselasma rhodostoma from Malaysia, Thailand, Indonesia, and Vietnam, as well as the individual venom of Trimeresurus mucrosquamatus collected from both North and South Taiwan. Enzymatic and pharmacological activities of the purified PLA2s were also investigated. The complete amino acid sequences of the purified PLA2s were determined by sequencing the corresponding cDNAs from the venom gland and shown to be consistent with their molecular weight data and the N-terminal sequences. All the geographic venom samples of C. rhodostoma contain a major noncatalytic basic PLA2-homolog and two or three acidic PLA2s in different proportions. These acidic PLA2s contain Glu6-substitutions and show distinct inhibiting specificities toward the platelets from human and rabbit. We also found that the T. mucrosquamatus venoms from North Taiwan but not those from South Taiwan contain an Arg6-PLA2 designated as TmPL-III. Its amino acid sequence is reported for the first time. This enzyme is structurally almost identical to the low- or nonexpressed Arg6-PLA2 from C. rhodostoma venom gland, and thus appears to be a regressing venom component in both of the Asian pitvipers.

Actinopolymorpha singaporensis gen. nov., sp. nov., a novel actinomycete from the tropical rainforest of Singapore

A novel actinomycete was isolated from soil in the tropical rainforest of Singapore. The cells of this actinomycete are highly pleomorphic. In the early stages of growth, most cells are of irregular squarish shape and varied sizes. Cells remain attached after cell division, often forming chains or aggregates of a few cells. Cells at the end of a chain tend to elongate. With prolonged cultivation, cells show different degrees of elongation and enlargement, producing branched hyphae of uneven thickness. At the periphery of the colony, long hyphae form, which are divided into alternating segments of elongated cells and chains of squarish cells. This actinomycete is considerably salt-tolerant, able to grow in the presence of 15% NaCl. Chemotaxonomically, it contains LL-diaminopimelic acid (DAP) in the cell wall, type PI phospholipids and MK-9(H6) as the predominant menaquinone. 16S rDNA sequence analysis assigned this actinomycete to the family Nocardioidaceae, but its 16S rDNA shared no more than 91.2% sequence similarity with other members of the family. Based on phenotypic, chemotaxonomic and phylogenetic evidence, it is proposed that this actinomycete be classified as a new species in a new genus, Actinopolymorpha singaporensis gen. nov., sp. nov.

Serine protease isoforms of Deinagkistrodon acutus venom: cloning, sequencing and phylogenetic analysis

The major coagulating fibrinogenase of Deinagkistrdon acutus venom, designated acutobin, was purified by anion-exchange chromatography, gel filtration and reverse-phase HPLC. Approximately 80% of its protein sequence was determined by sequencing the various fragments derived from CNBr cleavage and digestion with endoprotease. Extensive screening of the venom gland cDNA species after amplification by PCR resulted in the isolation of four distinct cDNA clones encoding acutobin and three other serine proteases, designated Dav-PA, Dav-KN and Dav-X. The complete amino acid sequences of these enzymes were deduced from the cDNA sequences. The amino-acid sequence of acutobin contains a single chain of 236 residues including four potential N-glycosylation sites. The purified acutobin (40 kDa) contains approx. 30% carbohydrate by weight, which could be partly removed by N-glycanase. The phylogenetic tree of the complete amino acid sequences of 40 serine proteases from 18 species of Crotalinae shows functional clusters reflecting parallel evolution of the three major venom enzyme subtypes: coagulating enzymes, kininogenases and plasminogen activators. The possible structural elements responsible for the functional specificity of each subtype are discussed.

Dopamine transporter and vesicular monoamine transporter knockout mice : implications for Parkinson's disease

One of the most valuable methods for understanding the function of a particular protein is the generation of animals that have had the gene encoding for the protein of interest disrupted, commonly known as a "quo;knockout"quo; or null mutant. By incorporating a sequence of DNA (typically encoding antibiotic resistance to aid in the selection of the mutant gene) into embryonic stem cells by homologous recombination, the normal transcription of the gene is effectively blocked (Fig. 1). Since a particular protein is encoded by two copies of a gene, it is necessary to have the gene on both alleles "quo;knocked out."quo; This is performed by cross-breeding animals with one affected allele (heterozygote) to generate offspring that have inherited two mutant alleles (homozygote). This procedure has been used to generate animals lacking either the plasma membrane dopamine transporter (DAT; Fig. 2) or the vesicular monoamine transporter (VMAT2; Fig. 3). Both DAT and VMAT2 are essential for dopamine homeostasis and are thought to participate in the pathogenesis of Parkinson's disease (1-5). Fig. 1. Maps of the targeting vector and the mock construct. The mouse genomic fragment (clone 11) was isolated from a Stratagene 129 SvJ library by standard colony hybridization using a PCR probe from the 5' end of rat cDNA. The restriction site abbreviations are as follows: H, HindIII; N, NotI; Sc, SacI; Sn, SnaI; X, XbaI; and Xh, XhoI. The region between HindIII and SnaI on clone 11 containing the coding sequence from transmembrane domains 3 and 4 of VMAT2 was deleted and replaced with PGK-neo. The 3' fragment of clone 11 was reserved as an external probe for Southern analysis. To facilitate PCR screening of embryonic stem cell clones, a mock construct containing the SnaI/XbaI fragment and part of the Neo cassette was generated as a positive control. pPNT and pGEM4Z were used to construct knockout and mock vectors, respectively. (Reproduced with permission from ref. 1). Fig. 2. DAT and VMAT2 expression in wild-type and DAT knockout midbrain. DAT immunoreactivity in wild-type (A) and DAT knockout midbrain (B). VMAT2 immunoreactivity in wild-type (C) and DAT knockout midbrain (D). Robust immunoreactivity was observed in the ventral tegmental area and substantia nigra pars compacta and reticulata in the wild-type brain. Note absence of DAT immunoreactivity and modest reduction of VMAT2 immunoreactivity in the DAT knockout. Fig. 3. Characterization of VMAT2 gene disruption. (A) Southern blot analysis of mouse genomic DNA. The Southern blot was prepared with 15 μg of genomic DNA per lane and probed with a 1.4-kb 3' external genomic fragment. +/+, wild type littermates; +/-, heterozygote; -/-, homozygote. (B) RT-PCR analysis of mouse brain poly(A)+ RNA. For each reverse transcription assay, 0.5 μg of poly(A)+ RNA was used. Equal volumes of cDNA templates were used for each PCR assay. The PCR primers used flank the neomycin cassette for the purpose of detecting potential readthrough of the neomycin DNA. The heterozygote has a reduced amount of transcripts compared with the wild-type littermate; the homozygote is devoid of VMAT2 transcripts. G3PDH was used as internal control. (C) Western blot analysis of wholebrain synaptic vesicles. Samples (25 μg) of vesicles were solubilized and separated by SDS-PAGE, transferred to nitrocellulose, subjected to Western blot analysis with anti-VMAT2-Ct (top) or anti-a-tubulin (bottom) antibodies, and developed with chemiluminescence. Molecular mass markers (kDa) are shown to the left. To confirm equal loading and transfer of proteins, the blots were stripped and reprobed with an antibody to α-tubulin. (Reproduced with permission from ref. 1). The importance of DAT in neuronal function is highlighted in animals in which DAT has been genetically deleted (DAT KO) (3). In the homozygote DAT KO mice, released dopamine remains in the extracellular space up to 300 times longer than normal. As expected, these animals display behaviors consistent with persistent activation of dopamine receptors, such as hyperlocomotion. Genetic deletion of VMAT2 reveals the essential role of vesicular storage and release of monoamines. Homozygote VMAT2 knockout mice survive for only a few days, whereas heterozygotes appear normal. Studies performed in homozygote pups and heterozygote adults clearly show that the level of VMAT2 expression calibrates the level of vesicular filling (1,2,bi4). With only 50% of normal VMAT2, heterozygote animals have reduced vesicular filling and release. These alterations in presynaptic monoamine function in the heterozygotes are thought to be responsible for the observed sensitization to the psychostimulants cocaine and amphetamine and to ethanol (1). Knockout animals also appear to parallel the changes that occur in reserpinized animals, suggesting that the adverse actions of this drug are mediated by VMAT2.