Ultra-high resolution SPECT system using four pinhole collimators for small animal studies

We describe a newly developed ultra-high resolution SPECT system using four pinhole collimators for small animal studies.

METHODS

The system utilizes a clinical four-head SPECT scanner with specially designed pinhole collimators. Four types of pinholes with different configurations were designed with different effective aperture sizes (1.0, 2.0 and 4.0 mm) and rotating radii (40 mm and 50 mm). The distance from the axis of rotation to the scintillator was fixed to 180 mm. A filtered backprojection algorithm was used to reconstruct SPECT images after fanbeam-to-parallel-beam data conversion.

RESULTS

The system provided a reconstructed spatial resolution of 1.65 mm (FWHM) and sensitivity of 4.3 kcps/microCi/ml with the best type of pinholes, respectively. The 99mTc-HMPAO SPECT image in rat studies clearly visualized small brain structures, and the left ventricular myocardium and cardiac cavity were clearly separated with 99mTc-MIBI. Dynamic SPECT imaging of rat brain with [123I]iomazenil was also feasible.

CONCLUSION

This ultra-high resolution SPECT system can be used to measure the regional distribution of radiolabeled tracers in small animals in vivo and may play a significant role in the development of new radiopharmaceuticals and in studies of various disease models using living animals.

Cyclic change in 3 alpha-hydroxysteroid dehydrogenase in rat ovary during the estrous cycle

3 alpha-Hydroxysteroid dehydrogenase (3 alpha-HSD) activity and content in the rat ovary were measured at various stages of the estrous cycle, and the enzyme protein in the ovary was localized by immunohistochemistry. The cyclic change of ovarian 3 alpha-HSD activity towards 5 alpha-dihydrotestosterone (5 alpha-DHT) as a substrate was characterized by two peaks. The first peak occurred at 0800 h on proestrus; then the reductase activity decreased and reached its minimum at 2000 h on proestrus. Thereafter, it gradually increased, reaching the second peak (170% of the value at 2000 h on proestrus) at noon of estrus. Quantitative analysis by immunoblotting revealed that the alteration in 3 alpha-HSD content in the rat ovary during the estrous cycle was essentially similar to that in 5 alpha-DHT reductase activity. Changes in the reductase activities towards 5 alpha-androstane-3,17-dione and 5 alpha-DHT and in the dehydrogenase activity towards androsterone in the ovary were entirely different from those in the 5 alpha-DHT reductase activity and 3 alpha-HSD content; on the other hand, the change in carbonyl reductase activity towards p-nitroacetophenone was similar to changes in 5 alpha-DHT reductase activity and 3 alpha-HSD content. Therefore, p-nitroacetophenone may be a useful substrate, instead of 5 alpha-DHT, for detection of 3 alpha-HSD activity at a high sensitivity, since the p-nitroacetophenone reductase activity was 10-fold higher than the 5 alpha-DHT reductase activity. The enzyme was primarily localized in the granulosa cells and CL cells. At 2000 h on proestrus, however, the overall intensity of immunostaining in the granulosa cells of the Graafian follicles was markedly diminished. In addition, immunoreactivity in the CL cells at 0800 h on estrus was observed only in the cells outlining the CL in some cases.

Increase in oxygen tension after intraperitoneal N-methyl-DL-aspartate in rat cerebral cortex

An oxygen electrode equipped with a thermocouple enabled us to determine the absolute oxygen tension (PO2) in brain regions by taking account of local changes in temperature. Under urethane anesthesia, the PO2 of rat cerebral cortex was significantly increased up to 90 min after N-methyl-DL-aspartate administration (200 mg/kg, i.p.). This suggests that stimulation of NMDA receptors enhances oxygen supply to the cerebrum in vivo.

Genomic imprinting of p57KIP2, a cyclin-dependent kinase inhibitor, in mouse

p57KIP2 is a potent tight-binding inhibitor of several G1 cyclin/Cdk complexes, and is a negative regulator of cell proliferation. The gene encoding human p57KIP is located on chromosome 11p15.5 (ref. 2), a region implicated in both sporadic cancers and Beckwith-Wiedemann syndrome, a familial cancer syndrome, marking it a tumour suppressor candidate. Several types of childhood tumours including Wilm's tumour, adrenocortical carcinoma and rhabdomyosarcoma display a specific loss of maternal 11p15 alleles, suggesting that genomic imprinting plays an important part. Genetic analysis of the Beckwith-Wiedemann syndrome has indicated maternal carriers as well as suggested a role in genomic imprinting. Here, as a first step towards elucidating the genesis of human cancers in this region, we showed that a mouse homologue of p57KIP2 is genomically imprinted. The paternally inherited allele is transcriptionally repressed and methylated. This murine gene maps to the distal region of chromosome 7, within a cluster of imprinted genes, including insulin-2, insulin-like growth factor-2, H19 and Mash2 (refs 14-18).

Copy-dependent and position-independent expression of rat aldolase A gene

In order to understand the molecular mechanisms of the temporal and spatial differences of gene expression in higher organisms, rat aldolase A gene carrying two distinct promoters was introduced into fertilized eggs and the resulting transgenic mice were analyzed. The transgene expression is tissue-specific and is developmentally regulated. In addition, the expression is regulated in a copy-dependent manner irrespective of where the transgene is integrated, suggesting that a mechanism excluding the effect of the integration site exists within the transgene itself. To explore the conformational change of this gene in the genome, the DNase I hypersensitive sites of the gene were examined. Three sites (DHS-1,2, and 3) were identified upstream and downstream of the gene and these sites were retained in the transgene as well as in the gene observed endogenously.

Unusual findings in a fatal case of poisoning with chromate compounds

An interesting case of acute poisoning by chromate compounds is reported. A 51-year-old man committed suicide by ingesting a fatal dose of sodium chromate solution. He unexpectedly lost consciousness 6 h after the ingestion and died approximately 20.5 h later. An examination of the blood showed noticeable hepatic damage and thrombocytopenia. The postmortem examination revealed extensive bleeding in the alimentary tract and a severe hepatic lesion due to hepatocellular necrosis. However, the renal disorder was unusually light in the microscopic and clinical findings. Moreover, the renal lesion was observed mainly in the distal tubules instead of the proximal tubules which is more typical in cases of acute poisonings by diverse heavy metals including chromium. The patient's death was assumed to have been caused by circulatory collapse due to internal bleeding and the direct toxicity of chromate compounds with hepatic malfunction and possibly disseminated intravascular coagulation (DIC).

The MEF2B homologue differentially expressed in mouse embryonal carcinoma cells

The MEF2 gene family encodes a MADS-box transcription factor which regulates expression of many muscle-specific genes. We examined the expression of the MEF2 genes in mouse embryonal carcinoma P19 cells before and after in vitro muscle differentiation induced by dimethyl sulfoxide (DMSO). At least three different MADS/MEF2 domains (MEF2A, 2B and 2D) were isolated from P19 cells with the MOPAC technique (mixed oligonucleotides primed amplification of cDNA). Although two of the MADS/MEF2 domain sequences were identical to those of human MEF2A and MEF2D, another domain sequence was similar but not identical to that of human MEF2B. While the transcription of MEF2A and MEF2D was up-regulated during differentiation of P19 cells, the MEF2B homologue was abundantly transcribed in undifferentiated P19, F9 and ES cells and down-regulated in adult heart, skeletal muscle or brain, suggesting that the murine MEF2B homologue might have a function distinct from other members of the MEF2 gene family in embryogenesis and development.

Effect of Helicobacter pylori eradication on the healing and recurrence of peptic ulcer: combination therapy with low-dose omeprazole and clarithromycin

AIM

To investigate the effect of eradication of Helicobacter pylori using combination therapy with low-dose omeprazole and clarithromycin on the healing and recurrence of peptide ulcers.

PATIENTS AND METHODS

We studied 60 patients with active duodenal ulcers and 60 with gastric ulcers who were H. pylori-positive by the rapid urease test and a histological examination of antral biopsy specimens. The eradication method used was a combination of omeprazole (20 mg a day) and clarithromycin (400 mg twice a day). The patients were followed up for 24 months after the end of the treatment. H. pylori infection and the ulcer stage were investigated by endoscopy every 6 months. We assessed the relationship between H. pylori infection, ulcer healing to a white scar and ulcer recurrence after combination therapy.

RESULTS

H. pylori was eradicated in 23 out of 120 patients (22%), with suppression in 101 out of 120 patients (84%). The rate of ulcer healing to a white scar 6 months after treatment was significantly higher and the ulcer recurrence rate within 2 years after treatment was significantly lower in patients with H. pylori suppression or eradication than in those continuously positive for the organism.

CONCLUSIONS

These results suggest that not only the eradication but also the suppression of H. pylori may improve ulcer healing and reduce the rate of relapse.

Simple quantification of benzodiazepine receptor binding and ligand transport using iodine-123-iomazenil and two SPECT scans

The feasibility of simplified procedures for the quantification of benzodiazepine receptor binding using [123I]iomazenil and SPECT was assessed.

METHODS

Six normal male volunteers were studied. Following intravenous injection of 111 MBq [123I]iomazenil, serial dynamic SPECT scanning was performed for 120 min and the concentration of lipophilic compounds in the arterial plasma was determined by chloroform extraction. Kinetic parameters were estimated by a curve-fitting procedure using the following four models: three-compartment, four-parameter (K1-k4) (3C4P), three-compartment, three-parameter (fixed K1/k2) (3C3P), three-compartment, two-parameter (fixed K1/k2 and k4) (3C2P) and two-compartment, two-parameter (K1 and k2) (2C2P). Kinetic parameters were also calculated by a table look-up procedure with 3C2P using only two SPECT data acquisitions. Parametric images were generated based on the same procedure.

RESULTS

In all models, the curve-fitting procedure gave similar outcomes for ligand transport (K1) and receptor density parameters (i.e., binding potential or distribution volume). The 3C4P parameters showed significant correlation between k2 and k3, while 3C3P did not show such a correlation, suggesting the stability of 3C3P. The 3C2P provided parameters essentially identical to those with the 3C3P, indicating the suitability of this model, while 2C2P gave similar distribution volume but obviously low K1.

CONCLUSION

Table look-up procedures based on the 3C2P model permit quantification of benzodiazepine receptor binding using [123I]iomazenil with two SPECT scans. This method may be of clinical value in the diagnosis of various diseases.

Radiolabeled metabolites of proteins play a critical role in radioactivity elimination from the liver

We have recently reported that the behavior of radiolabeled metabolites in the liver appears to be responsible for the hepatic radioactivity levels after administration of protein radiopharmaceuticals. To better understand the role played by radiolabeled metabolites in hepatic radioactivity levels, two benzyl-EDTA derivatives rendering different radiolabeled metabolites, 1-(4-isothiocyanatobenzyl)ethylenediaminetetraacetic acid (SCN-Bz-EDTA) and 1-[p-(5-maleimidopentyl)aminobenzyl]ethylenediaminetetraacetic acid (ECMS-Bz-EDTA), were selected as bifunctional chelating agents (BCAs), and 111In labeling of galactosyl-neoglycoalbumin (NGA) and mannosyl-neoglycoalbumin (NMA) was performed. Biodistribution of radioactivity in mice and subcellular distribution of radioactivity in hepatocytes were then compared. After accumulation in hepatic parenchymal cells, NGA-EMCS-Bz-EDTA-111In rendered a faster elimination rate of radioactivity from the liver than NGA-SCN-Bz-EDTA-111In. Although each 111In-NMA exhibited a delayed elimination rate of radioactivity from the liver compared to the 111In-NGA counterpart, NMA-EMCS-Bz-EDTA-111In showed faster elimination rate of radioactivity than NMA-SCN-Bz-EDTA-111In. Analyses of radioactivity excreted in feces and urine and remaining in the liver indicated that both BCAs rendered mono-amino acid adducts as the major radiolabeled metabolites (cysteine-EMCS-Bz-EDTA-111In and lysine-SCN-Bz-EDTA-111In), which were generated in both cell types of the liver within 1 h postinjection. Subcellular distribution of radioactivity indicated that the radioactivity was copurified with lysosomes. These results demonstrate that although in vivo stability of radiometal chelates is essential, the biological properties of the radiolabeled metabolites generated after lysosomal proteolysis in hepatocytes play a critical role in radioactivity elimination from the liver.

Identification of the major capsid protein gene of human herpesvirus 7

Two human herpesvirus 6 (HHV-6) open reading frames were identified with significant amino acid similarity to UL86 (major capsid protein, MCP) and UL85 of human cytomegalovirus (HCMV) in human herpesvirus 7 (HHV-7) genes. The predicted lengths of the complete HHV-7 MCP and the HCMV-UL85 open reading frames were 1344 and 293 amino acids with estimated molecular weights of approximately 153 and 33 kDa, respectively. Computer analysis showed that the amino acid of HHV-7 MCP was 61% identical to the MCP of HHV-6 variants A and B, 28% to HCMV. These results suggest that HHV-7 is more closely related to HHV-6 than to HCMV.

Follow-up observation of a patient with left ventricular thrombus by echocardiography

We report a case of left ventricular thrombus which caused systemic embolism during warfarin therapy. A 66-year-old man admitted to our hospital with intermittent loss of consciousness and incomplete palsy. The patient had a past history of cerebral infarction, hypertension and diabetes mellitus. Electrocardiography showed abnormal Q waves at II, III, and aVF. Echocardiography showed a mobile protruding thrombus at the left ventricular apex. Left ventricular cineangiography showed a filling defect at the left ventricle. Coronary angiography confirmed total occlusion of the right coronary artery and significant stenosis of the left coronary artery. After administration of warfarin, the patient suddenly fell down to the comatose state. His left arm became pale without pulsation. The thrombus in the left ventricle disappeared by echocardiography and systemic embolism was suspected. Thromboembolectomy from his left arm was performed. Two weeks after the day brain computed tomography showed low density area at the posterior lobe of the cerebrum. Although the eyesight of the patient was lost, he could stand and walk with some help two months later. This is a rare case of systemic embolism during warfarin therapy due to left ventricular thrombus whose process was constantly observed by echocardiography.

Cloning and mapping of the U2af1-rs2 gene with a high transmission distortion in interspecific backcross progeny

We have cloned and analyzed the mouse U2af1-rs2 gene based on its sequence similarity to the imprinted gene U2af1-rs1 (SP2). Sequence analysis of this U2af1-rs2 cDNA revealed that it contained an open reading frame encoding a protein of 462 amino acid residues. The predicted amino acid sequence showed 72.7 and 35.8% identity to the U2af1-rs1 and U2 small nuclear ribonucleoprotein auxiliary factor, respectively. Interspecific backcross analysis showed this gene to map to the distal region of the X chromosome and also indicated that there was significant distortion of transmission ratio of the U2af1-rs2 allele in the backcrossed progeny from (C57BL/6J x Mus spretus)F1 females mated to Mus spretus males.

Transfer of dietary sulphamonomethoxine and sulphadimethoxine into various tissues of laying hens

1. Sulphamonomethoxine (SMM) or sulphadimethoxine (SDM) were fed to laying hens at a dietary concentration of 400 mg/kg. Concentrations (mg/kg) of SMM and SDM in the blood, kidney, liver, ovary, muscle and adipose tissue, collected at 4, 8, 16 and 24 h after the start of feeding, were determined by HPLC. 2. The relationships between the sulphonamide concentrations (mg/kg) in the tissues and times (h) after the start of the feeding were analysed statistically. 3. Dietary SMM and SDM were transferred throughout the whole body, and concentrations in all tissues became constant 8 h after the start of feeding. 4. Among the 6 tissues examined the constant values (mg/kg) of both SMM and SDM were highest in the kidney and were lowest in adipose tissue. 5. With the exception of adipose tissue, the values of SDM in the tissues were statistically greater than those of SMM.

[Arterial oxygen saturation monitoring of sleeping infants by pulse-oximeter--effect of sleeping position on arterial oxygen saturation in infants]

Monitoring of the arterial oxygen saturation (SaO2) in two sleeping infants was reported. They were a couple of female twins and had grown up normally after admission to NICU (Neonatal Intensive Care Unit) for a month. We investigated their SaO2 with the puls-oximeter at the terms between the 2nd and the 10th month. There was no significant difference between SaO2 in prone positions (n = 29) and that in supine positions (n = 30). In the infant with the sniffing conditions, however, SaO2 in prone positions seemed to be slightly lower than that in the healthy conditions. The slightly low SaO2 would give no effects on the healthy infants, but it may cause ALTE (Apparent Life Threatening Event) or death from SIDS (Sudden Infant Death Syndrome) to some infants who are not in good health and/or who are prone to get into ALTEA or SIDS. Especially, in the sniffing condition with hyperthermia, as the oxygen dissociation curve sifts to right and SaO2 degradation appears easily, sudden infant death may be possible to happen in prone position.

Carcinosarcomas of the esophagus

Two cases of carcinosarcoma of the esophagus are reported. Both were polypoid tumors occurring in the middle of the intrathoracic esophagus. The tumors were predominantly composed of spindle-shaped sarcoma cells with some squamous cell carcinomas (SCC). One tumor showed many bizarre giant cells with filamentous materials in the cytoplasm. Microscopical examination of both tumors revealed transition from SCC to sarcoma cells. Immunohistochemically, the spindle-shaped sarcoma cells in both tumors displayed a strongly positive immunoreaction to alpha-smooth muscle actin, as did the bizarre giant cells of one tumor to sarcomeric actin. SCC and a few spindle-shaped sarcoma cells near the SCC showed a positive immunoreaction to cytokeratin. Electron microscopy revealed that the spindle-shaped cells had many myofilaments with dense bodies and that the bizarre giant cells had sarcomere structures with Z-bands in their cytoplasm. These findings indicate that both tumors were carcinosarcomas of SCC and myogenic sarcoma. We considered that sarcoma cells might originate in SCC, representing its metaplastic differentiation, or that both SCC and sarcoma might originate in a pluripotent stem cell.

High-power erbium-doped fiber laser mode locked by a semiconductor saturable absorber

Using an erbium-doped fiber laser (EDFL) passively mode locked by a semiconductor saturable absorber, we generate 5.5-ps pulses of a 2.3-nJ/pulse, which are more than three times higher in energy than for other reported EDFL's. We show that, by introduction of a linear loss element within the cavity, multiple pulsing behavior at high pump powers can be suppressed. We also determine the saturable-absorber characteristics-absorbance versus wavelength near band gap-that are necessary to produce short mode-locked pulses.

Parents' contributions to children's knowledge and attitudes regarding AIDS: another look

Attempted to determine, using a sample of students in Grades 3, 5, and 7, whether parent-child communication about AIDS and parent knowledge of AIDS predict children's knowledge, social attitudes, and worry regarding AIDS, partially replicating tests by Sigelman, Derenowski, Mullaney, and Siders (1993) of main effects, interaction, and potentiation models of parent-child socialization. Most parents had talked to their children about AIDS but many were susceptible to myths about HIV transmission. Child age was the strongest predictor of accurate knowledge and positive attitudes, but gender, ethnicity, and parent education also made modest contributions. Consistent with the potentiation model, parent knowledge of common transmission myths predicted child knowledge of those same myths (and willingness to interact with individuals who have AIDS as well) only when parent-child communication about AIDS was relatively extensively (and only when child rather than parent reported it). Findings suggest that both the quantity and quality of parental messages must be considered by socialization researchers but that parents may not be the primary socializers of knowledge and attitudes regarding AIDS and other health issues.

Allele-specific methylation and expression of an imprinted U2af1-rs1 (SP2) gene

The mouse U2af1-rs1(SP2) gene, which was cloned by a two-dimensional genome scanning method, is expressed exclusively from the paternally inherited chromosome. This gene has significant similarity to U2AF and located in chromosome 11, of which maternal duplication/paternal deficiency results in a small body. In this report, we cloned genomic U2af1-rs1(SP2) and found its promoter was methylated in a maternal-allele-specific manner. This allelic methylation was not established in parental gametes, but established between 1.5 d.p.c. and 12.5 d.p.c. on the contrary, the allele-specific expression occurred in the two-cell stage when transcription initiates. Absence of the methylation of the upstream region in this stage indicates that methylation is not necessary for inactivation of the expression.

On the evolution of dust in the solar vicinity

The analysis of interplanetary dust shows that the majority of particles in out-of-ecliptic regions comes from comets and also that near solar dust, in the ecliptic regions, results most probably largely from comets. The intense radiation flux in the solar vicinity is expected to cause strong modifications in the material composition and surface structure of interplanetary dust particles and hence the analysis of near solar dust provides interesting insights into the evolution of meteoritic, especially cometary materials. Because of the lack of in-situ measurements our present knowledge concerning these processes derives from remote sensing, i.e. observations of the solar F-corona. In particular these are observations of albedo, polarization and colour temperature given in terms of average particle properties. For example the analysis of near infra-red F-corona data points to the existence of a strong component of irregularly structured silicate particles, most probably of cometary origin. The data may indicate a subsequent sublimation of different particles or different constituents of the particles. Here we compare particle properties derived from F-corona observations with model calculations of single particle properties and discuss perspectives of future analysis of cometary dust in the interplanetary cloud.

Urinary bladder-selective action of the new antimuscarinic compound vamicamide

1. The inhibitory action of vamicamide (FK176, (+/-)-(2R*,4R*)-4-dimethylamino-2-phenyl-2-(2-pyridyl)valeramide, CAS 132373-81-0) on the responses of various tissues to the cholinergic agonists, carbachol and McN-A-343 (4-[m-chlorophenylcarbamoyloxy]-2-butynyl-trimethylammonium chloride, CAS 55-45-8), was investigated in isolated tissue preparations. Vamicamide showed competitive antagonistic actions against all the preparations tested and its pA2 value for the urinary bladder was 6.82, which was higher than that for the atria (5.94) and almost the same as that for the vas deferens (6.90) and for the stomach (6.81). The pA2 values of oxybutynin hydrochloride (oxybutynin) and atropine sulfate monohydrate (atropine) were nearly the same in all the tissues tested. 2. Oral administration of vamicamide 0.1-1.0 mg/kg inhibited dose-dependently spontaneous bladder contractions caused by raising the intravesical volume in conscious rats. Inhibitory actions were also obtained with 0.32-3.2 mg/kg of oxybutynin or 0.0032-0.032 mg/kg of atropine, but the duration of action of oxybutynin was shorter than that of vamicamide or atropine. Vamicamide further inhibited bladder contractions in rats following intravesical administration of 0.05-0.5 mg/ml solution. 3. Vamicamide had no effect or only slightly inhibited spontaneous motility of the stomach and distal colon in conscious rats, as well as heart rate and salivary secretion in conscious dogs, after oral dosing with 3.2 mg/kg of the compound. Similar results were obtained with oxybutynin, excepting the occurrence of tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dynamic cardiomyoplasty on phasic coronary arterial flow velocity in canine hearts

The usefulness of dynamic cardiomyoplasty has been demonstrated repeatedly, both experimentally and clinically. Although clinical applications of dynamic cardiomyoplasty to ischemic heart disease have been reported, its effect on the coronary blood flow has never been discussed. Therefore, we tested the hypothesis that dynamic cardiomyoplasty might adversely affect coronary arterial blood flow through compression of the coronary arteries during systolic skeletal muscular contraction and incomplete relaxation of the skeletal muscle flap during diastole. Dynamic cardiomyoplasty was performed in seven mongrel dogs with the use of a left latissimus dorsi-muscle flap, paced synchronously with the R wave of the electrocardiogram. A 3F Doppler catheter was placed in the left main trunk of the coronary artery to assess the instantaneous changes of coronary flow velocity by fast Fourier transformation analysis, We compared systolic and diastolic properties during assisted versus unassisted cardiac cycles by calculating the peak velocity and the time-velocity integral. During assisted cardiac cycles, a significant enhancement of coronary arterial blood flow velocity was demonstrated by significant increases in both systolic and diastolic peak velocity (26.9% +/- 6.5%, p < 0.005; 4.0% +/- 1.6%, p < 0.05, respectively) and time-velocity integral (20.9% +/- 4.8%, p < 0.05; 10.0% +/- 4.6%, p < 0.05, respectively). Enhancement of coronary arterial blood flow velocity was associated with an increase in mean aortic pressure (16.4% +/- 1.3%, p < 0.005) and descending aortic flow (67.5% +/- 5.3%, p < 0.005). Also, the improved systolic coronary arterial blood flow velocity was consistent with an increase in systolic aortic pressure (15.8% +/- 1.5%, p < 0.005), and enhancement of diastolic coronary arterial blood flow velocity was associated with an increase in diastolic aortic pressure (8.6% +/- 2.3%, p < 0.01). We concluded that coronary arterial blood flow velocity was increased by the enhancement of cardiac function as a result of dynamic cardiomyoplasty, leading to an increase of coronary perfusion pressure and cardiac output.