Methylation of the hMLH1 promoter in familial gastric cancer with microsatellite instability

Microsatellite instability (MSI), which is recognized as an important mechanism in tumorigenesis, has been reported in familial gastric cancers (FGC). However, genetic defects responsible for this phenotype, that is, mutations in mismatch-repair genes such as hMLH1 and hMSH2, have not been detected in most FGC cases. Earlier studies have shown that the promoter region of the hMLH1 gene was methylated in some sporadic colorectal and endometrial cancers. To determine how FGC acquire MSI, we examined the MSI status, hMLH1-protein expression and methylation status of the hMLH1-promoter region in FGC cases. Out of 9 cancers, 6 from 8 FGC kindreds showed MSI at one or more loci; no germline mutations in the hMLH1 or hMSH2 genes were detected; 4 cancers exhibiting MSI displayed aberrant hMLH1 expression: complete loss in one, decreased level in another, and partially staining pattern in the remaining 2. Methylation in the hMLH1-promoter region was found in these 4 cases. In contrast, the cancers displaying hMLH1-protein expression were not methylated in the hMLH1-promoter region. Our data show a significant association between the absence of hMLH1 expression and methylation of its promoter in FGC cases with MSI. This suggests that the mechanism of inactivation of hMLH1 is epigenetic and that there are other genes responsible for FGC.

Methylation of the hMLH1 promoter in familial gastric cancer with microsatellite instability

Microsatellite instability (MSI), which is recognized as an important mechanism in tumorigenesis, has been reported in familial gastric cancers (FGC). However, genetic defects responsible for this phenotype, that is, mutations in mismatch-repair genes such as hMLH1 and hMSH2, have not been detected in most FGC cases. Earlier studies have shown that the promoter region of the hMLH1 gene was methylated in some sporadic colorectal and endometrial cancers. To determine how FGC acquire MSI, we examined the MSI status, hMLH1-protein expression and methylation status of the hMLH1-promoter region in FGC cases. Out of 9 cancers, 6 from 8 FGC kindreds showed MSI at one or more loci; no germline mutations in the hMLH1 or hMSH2 genes were detected; 4 cancers exhibiting MSI displayed aberrant hMLH1 expression: complete loss in one, decreased level in another, and partially staining pattern in the remaining 2. Methylation in the hMLH1-promoter region was found in these 4 cases. In contrast, the cancers displaying hMLH1-protein expression were not methylated in the hMLH1-promoter region. Our data show a significant association between the absence of hMLH1 expression and methylation of its promoter in FGC cases with MSI. This suggests that the mechanism of inactivation of hMLH1 is epigenetic and that there are other genes responsible for FGC.

A core promoter and a frequent single-nucleotide polymorphism of the mismatch repair gene hMLH1

The hMLH1 gene encodes a protein that is involved in the DNA mismatch repair system. The coding region of the hMLH1 gene has been known to be mutated in a subset of patients with hereditary nonpolyposis colorectal cancer (HNPCC). Our current research characterized the promoter region of the hMLH1 gene and searched for mutations correlating to HNPCC. Utilizing the oligo-capping method, major transcription start sites of the hMLH1 gene were mapped at two locations. The core promoter region of about 180 bp was determined by the luciferase assay of serial deletion mutants. Although we did not find any pathogenic mutation in the hMLH1 promoter region by PCR-SSCP, we found a single-nucleotide polymorphism at position -93 nt from the adenine residue of the start codon. By PCR-RFLP analysis with Pvu II for this polymorphism, we detected LOH in four tumors from three patients. An easy detection of this polymorphism with PCR-RFLP and high incidence ( approximately 50%) of informative cases make this polymorphism a suitable marker for the detection of hMLH1 allelic losses.

Two short sequences have positive effects on the human p27Kip1 gene transcription

The cyclin-dependent kinase (Cdk) inhibitor p27Kip1 plays an important role in the progression from G1 to S phase in the cell cycle. To study the activities of its promoter and other regulatory elements, we have cloned and characterized the 5'-flanking region of the human p27Kip1 gene. This region, about 3kb in length, is GC-rich and shares homology with that of the mouse p27Kip1 gene. Transcription start points (tsp) determined by the oligo-capping method are mapped in two regions, the cluster I (-479 to -403) and cluster II (-280 to -273). The cluster I was the primary functional site in transcription initiation. The luciferase activities of serial deletion mutants indicated that two short sequences (-581 to -557 and -556 to -526) had positive effects on transcription. The gel shift assay showed that factors in HeLa nuclear extract bound to these sequences. Sp1 was the major binding factor to the sequence of -556 to -526, wheres yet unidentified positive factors bound to the sequence of -581 to -557.

Determinants of nitrogen dioxide concentrations in indoor ice skating rinks

OBJECTIVES

The combination of poor ventilation and fuel-powered ice resurfacers has resulted in elevated nitrogen dioxide (NO2) concentrations in many indoor ice skating rinks. This study examined the factors influencing concentrations and the effects of various engineering controls in ice rinks with different resurfacer fuels.

METHODS

Indoor NO2 concentrations were measured in 19 enclosed ice skating rinks over 3 winters by means of passive samplers, with 1-week average measurements during the first winter pilot study and single-day working-hour measurements in the final 2 winters. Personal exposures to drivers also were assessed during the last winter.

RESULTS

Rinks in which propane-fueled resurfacers were used had a daily mean indoor NO2 concentration of 206 ppb, compared with 132 ppb for gasoline-fueled and 37 ppb for electric-powered resurfacers. Engineering controls, such as increased ventilation and resurfacer tuning, reduced NO2 concentrations by 65% on average, but outcomes varied widely, and concentrations increased in subsequent months.

CONCLUSIONS

Electric ice resurfacers, increased ventilation, or emission control systems are recommended to protect the health of workers and patrons, with surveillance programs proposed to track implementation and maintain an observer effect.

Human megasatellite DNA RS447: copy-number polymorphisms and interspecies conservation

We previously isolated a novel 4.7-kb RS447 sequence, which tandemly repeated approximately 50-70 copies and resided on human chromosome 4p15 (M. Kogi et al., 1997, Genomics 42: 278-283). Another tandem array (or arrays) of several RS447 copies was hereby identified on the distal part of chromosome 8p. To analyze copy-number polymorphisms of the RS447 repeats, genomic DNA samples of eight nonkindred Japanese were subjected to pulsed-field gel electrophoresis. The copy numbers of the RS447 tandem arrays on 4p15 varied drastically from allele to allele and ranged from approximately 34 to 94 copies. All eight Japanese subjects were apparently heterozygous for the RS447 copy number, and 12 copy-number-different alleles have been at least clearly distinguished. The RS447 tandem repeats were thus found to be hypervariable and highly polymorphic in a human population. The RS447 sequences, however, do not appear to be either "selfish" or "junk" DNA. The unit size and sequence of RS447 were found to be very similar between members in the human genome. The unit size of 4746 bp comprises a putative open reading frame of 1590 bp. The RS447 sequence was well conserved in all the tested mammalian species. The head-to-tail tandem repetitive structure in the RS447 homologs was also confirmed in those species. The RS447 sequence is, therefore, considered to consist of a new class of tandemly repeated satellite DNA elements in the mammalian genome, which may thus be called "megasatellite DNA."

The Boston residential nitrogen dioxide characterization study: classification and prediction of indoor NO2 exposure

Many epidemiological studies have used house characteristics associated with indoor sources as simplified proxies for personal nitrogen dioxide (NO2) exposure. Stove type and presence of a pilot light often been used as the two key characteristics, but significant overlaps have remained in the NO2 concentrations in the exposed and unexposed groups. This has contributed to inconsistencies in epidemiological findings, due to potential misclassification of exposure. In this study, other possible proxies were analyzed by cross-table analyses and were investigated in terms of improvements in both classification and predictive power. Adding building type to the above two proxies resulted in 0-5% of households with concentrations overlapping the observed range for the opposing stratum, compared with 22-42% for the two-proxy model. In spite of this performance, the predictive power of regression models for indoor NO2 was not improved by the addition of the third proxy, and the potential sample population was significantly limited. Using these analytical methods to choose descriptive proxies and evaluate the tradeoffs in their implementation can help epidemiological studies improve their designs and therefore optimize the robustness of their conclusions.

Promoter analysis of the human mismatch repair gene hMSH2

The human DNA mismatch repair gene homologue hMSH2 is involved in hereditary nonpolyposis colorectal cancer. We isolated and characterized the 5' upstream region, about 4.4kbp, of the hMSH2 gene. This region contains CpG islands and a number of elements involved in constitutive expression, but there is no TATA-box nearby the transcription start points. This is the typical structure for many promoters of housekeeping genes. Alu sequences and mononucleotide repeats are clustered in this region and there are two transcription start points. Deletion analysis revealed that less than 300bp was sufficient to initiate transcription. Although no mutation that influences promoter activity of this region was found, a polymorphism was detected by PCR-RFLP analysis. Because informative cases (C/T heterozygous) were relatively high ( approximately 30%), this polymorphism is suitable for a marker to examine allelic losses.

Impact of residential nitrogen dioxide exposure on personal exposure: an international study

Nitrogen dioxide (NO2) concentrations were measured during two-day winter periods in indoor and outdoor environments, and these concentrations were compared with simultaneously measured personal exposures in 18 cities in 15 countries around the world. Information was also gathered on activity patterns and household characteristics in order to determine the influences of these factors on personal exposures. All NO2 measurements were taken using passive filter badges. Personal exposures were found to vary greatly among the array of cities, with mean concentrations ranging between 11.0 ppb and 51.5 ppb. Personal NO2 exposures were more strongly correlated with indoor concentrations (r = 0.75) than with outdoor concentrations (r = 0.57) when all countries were considered simultaneously. Use of a gas stove in the home was the dominant activity influencing NO2 concentrations, with a 67% increase in mean personal NO2 exposure and an increase in indoor-outdoor ratios from 0.7 to 1.2 for participants using gas stoves, although preliminary evidence indicates the importance of combustion space heaters as well. These associations indicate the global nature of the correlation between personal NO2 exposures and indoor NO2 sources such as gas stoves or space heaters, demonstrating that this relationship is not dependent on country-specific parameters.

Isolation and characterization of the 5' region of the human mismatch repair gene hPMS1

The hPMS1 gene encodes a mutL homolog that is implicated in DNA mismatch repair and was found to be mutated in the germline of a patient with hereditary nonpolyposis colorectal cancer (HNPCC). To understand transcriptional regulation and to perform mutational analysis in the promoter region, we cloned and characterized the genomic sequence of the 5' region of the gene. hPMS1 has an intron upstream of the initiation codon. There were several transcripts with alternative splicing sites and multiple transcriptional start sites. The cloned 1.4-kbp fragment of the 5' region contains a CpG island but no TATA-boxes, typical for promoters of housekeeping genes. The promoter activity of the fragment was almost equal to that of the SV40 early promoter. Deletion analysis showed that about a 300-bp region was sufficient to initiate transcription. Although we searched for mutations in the hPMS1 promoter region in HNPCC kindreds, neither germline nor somatic mutations were detected. However, we found a highly informative polymorphism in the first exon that is useful for searching allelic losses because no polymorphic changes in hPMS1 have been reported previously.

Analysis of DNA from subjects found to be heterozygous for the haptoglobin-Johnson alpha gene

We found two rare Hp Johnson variant families (Hp2-Johnson type and Hp1-Johnson type) by PAGE. It was confirmed by SDS-PAGE that the haptoglobin molecules with the Hp Johnson variant consisted of alpha-2 or alpha-1 and alpha-3 subunits. Direct gene analysis of Hp Johnson heterozygous individuals using three endonucleases: EcoRI, HindIII and BamHI, showed a three-fold tandem repeat of the same 1.7-kb DNA fragment implicated in the Hp alpha-2 gene duplication, and this Hp-Johnson-specific extension was identified in two generations of the Hp2-Johnson and Hp1-Johnson families.

[Toxicity studies of landiolol hydrochloride (ONO-1101) (1). Single intravenous toxicity study in rats and dogs]

Single dose toxicity studies of landiolol hydrochloride (ONO-1101), a novel ultra short acting beta-blocker, were conducted in Sprague-Dawley (SD) rats and beagle dogs. ONO-1101 was administered intravenously at a dose level of 37.5, 75, 150 or 300 mg/kg to rats of both sexes and 25, 50 or 100 mg/kg to male dogs. In the rat study, 5/6 males in the 150 mg/kg group and all animals in the 300 mg/kg group died during or right after administration. Survivors in the 150 mg/kg group showed temporal hypoactivity, bradypnea, dyspnea, tremor, loss of righting reflex and reddish lacrimation up to 5 min after injection. One male in the 150 mg/kg group had a tendency of suppression on body weight gain. No effects on clinical signs and body weight gain were seen in the 75 mg/kg group or lower. Necropsy findings showed only red tear in the majority of the decedents. In the dog study, all animals died within 6 min after administration in the 100 mg/kg group, showed ataxic gait, rolling and tachypnea followed by bradypnea and gasping/apnea. Incontinence of urine, defecation and vocalization were also seen in each one of two animals before death. Temporal hypoactivity was seen 1 min after administration in the 50 mg/kg group. No clinical signs were seen in the 25 mg/kg group. ONO-1101 did not affect bodyweight or food consumption. Necropsy findings of the decedents showed no abnormalities. It is indicated that the minimum lethal doses are 150 mg/kg in rats and 100 mg/kg in dogs.

Association equilibrium of L-methamphetamine with serum albumin in various animal species

The association equilibrium of complex formation between serum albumin (bovine, rat, rabbit, guinea pig, horse, mouse and chicken) and L-methamphetamine (MAMP) was determined by the use of ultrafiltration to examine the effect of animal species on adsorption of L-MAMP to albmin. Serum albumin L-MAMP complexes had the same Scatchard plot patterns in all species tested. The binding parameters of each association equilibrium were estimated by Rosenthal's method. One kind of binding site and non-specific binding sites were distinguished in terms of the association equilibrium between each serum albumin and L-MAMP in all species tested.

Analysis of the affinity of each haptoglobin polymer for hemoglobin by two-dimensional affinity electrophoresis

Using polyacrylamide gel electrophoresis we have often encountered a decrease in the high molecular weight polymers of haptoglobin 2-1 in the serum of patients after transfusion and with hemolytic diseases. Using two-dimensional affinity electrophoresis we have attributed this phenomenon to the high affinity of high molecular weight polymers of the haptoglobin 2-1 for hemoglobin.

Binding of methamphetamine to serum albumin in various species in vitro

While drugs from experimental animals provide very important information, it is also true that data differ from species to species, and that data from experimental animals cannot be applied directly to humans. The binding parameters of serum albumin from various animal species and methamphetamine were investigated in vitro by the Scatchard method. The Scatchard plots for the binding of serum albumin and methamphetamine were classified into three patterns: straight lines for human and rat serum albumin; downwardly convex curves for bovine and rabbit serum albumin; and upwardly convex curves for horse, mouse and chicken serum albumin. Hill coefficients were calculated for binding in which the Scatchard plots were upwardly convex curves and for guinea pig serum albumin. The results suggested the existence of positive cooperativity between the methamphetamine binding sites on serum albumin from the horse, mouse, chicken and guinea pig. Furthermore, the process of methamphetamine binding to human serum albumin appears to differ from the process for all experimental animals except the rat, and there are also differences between the binding processes in the various experimental animals.

Comparison of two-photon excitation laser scanning microscopy with UV-confocal laser scanning microscopy in three-dimensional calcium imaging using the fluorescence indicator Indo-1

Two-photon excitation laser scanning fluorescence microscopy (2p-LSM) was compared with UV-excitation confocal laser scanning fluorescence microscopy (UV-CLSM) in terms of three-dimensional (3-D) calcium imaging of living cells in culture. Indo-1 was used as a calcium indicator. Since the excitation volume is more limited and excitation wavelengths are longer in 2p-LSM than in UV-CLSM, 2p-LSM exhibited several advantages over UV-CLSM: (1) a lower level of background signal by a factor of 6-17, which enhances the contrast by a factor of 6-21: (2) a lower rate of photobleaching by a factor of 2-4; (3) slightly lower phototoxicity. When 3-D images were repeatedly acquired, the calcium concentration determined by UV-CLSM depended strongly on the number of data acquisitions and the nuclear regions falsely exhibited low calcium concentrations. probably due to an interplay of different levels of photobleaching of Indo-1 and autofluorescence, while the calcium concentration evaluated by 2p-LSM was stable and homogeneous throughout the cytoplasm. The spatial resolution of 2p-LSM was worse by 10% in the focal plane and by 30% along the optical axis due to the longer excitation wavelength. This disadvantage can be overcome by the addition of a confocal pinhole (two-photon excitation confocal laser scanning fluorescence microscopy), which made the resolution similar to that in UV-CLSM. These results indicate that 2p-LSM is preferable for repeated 3-D reconstruction of calcium concentration in living cells. In UV-CLSM, 0.18-mW laser power with a 2.6-phi pinhole (in normalized optical coordinate) gives better signal-to-noise ratio, contrast and resolution than 0.09-mW laser power with a 4.9-phi pinhole. However, since the damage to cells and the rate of photobleaching is substantially greater under the former condition, it is not suitable for repeated acquisition of 3-D images.

Estimation of CO exposure of road construction workers in tunnel

Carbon monoxide (CO) level in three different tunnels in Boston area have been measured during rush hour periods, and expected CO exposure of construction workers who possibly work there was also estimated. CO levels in these tunnels have been measured at outside of a car running through the tunnels. The data collected in this study include vehicle speed, length of tunnels and traffic volume. In addition, structure of each tunnel was investigated. These data were used to estimate relationship between CO level and the distance of sampling points from entrance/exit of each tunnel. CO concentration in each tunnel was distributed in the range of 5 ppm-42 ppm, and linear relationship between CO concentration and distance from entrance/exit has been observed. This study had been held from April 1989 to May 1989 in Boston, MA, USA.

Determination of intermediates of hemoglobin-haptoglobin complex of haptoglobin polymers by "Crossed hemoglobin electrophoresis"

We designed a "crossed hemoglobin electrophoresis" to be able to detect the intermediates of a hemoglobin-haptoglobin complex without the need for the purification step of haptoglobin molecules. Native polyacrylamide gel electrophoresis was performed as the first dimensional electrophoresis followed by a cross to hemoglobin as the second dimensional electrophoresis. Using this method, we found that a number of intermediates of normal Hp 2-2, Hp 2-1 polymers, particularly those from the trimer to the pentamer, were detected on a polyacrylamide gel. Each of their polymers combined to the hexamer with at least an equimolar content of hemoglobin. In the process of detecting the haptoglobin serotype of more than 10,000 patients for the clinical utilization of quantitative analytical data, we observed two haptoglobin variants, the Hp Johnson and a haptoglobin serotype similar to the Carlberg type. Using our crossed hemoglobin electrophoresis, we also detected the capacity for combining with hemoglobin of each polymer of these variants.

Latent high jugular bulb: case report and significance of neck compression test

High jugular bulb is a vascular anomaly seen in the middle ear. In typical cases, the jugular bulb is easily observed through the tympanic membrane. We report here 3 patients with nontypical high jugular bulb. Their tympanic membranes were almost normal but protruded externally with pulsation when their necks were compressed. Computed tomography (CT) revealed jugular bulb protrusion into the tympanic cavities. We propose that this condition be named 'latent high jugular bulb'. Neck compression easily detects this condition and may also be useful in the detection of other disorders of the middle ear that are related to the venous system.

Determinations of personal carbon monoxide exposure and blood carboxyhemoglobin levels in Korea

Determinant factors for personal carbon monoxide (CO) exposures were sought in Korea, where CO poisoning has been a major public health problem due to coal briquette (Yeontan) combustion for space heating and cooking. Personal 24-hr CO exposures of 15 housewives were measured by CO passive samplers on 2 days of the week (Wednesday and Sunday). Blood samples were taken to measure carboxyhemoglobin (COHb) just after the exposure sampling. Average CO exposure and COHb level were 5.6 ppm and 2.4%, respectively. Personal CO exposures as well as COHb levels were significantly increased by the use of Yeontan, especially on a weekday. Carboxyhemoglobin levels were closely related to the time between blood collection and replacement of Yeontan: the closer the blood collection was to replace Yeontan, the higher the COHb levels were. Assuming a background COHb of 1.34%, COHb increased on average by 1.8% with a 24-hr personal CO exposure of 10 ppm. The relationship between CO exposure and COHb level was provided by simultaneous direct measurements in real environment, although a measurement of COHb at the end of exposure could not represent previous 24-hr exposure thoroughly.

[The effect of temocapril, an angiotensin-converting enzyme inhibitor with preferential biliary excretion, on experimental diabetic nephropathy]

Tempocapril is a novel angiotensin-converting enzyme (ACE) inhibitor which is preferentially eliminated via the biliary tract. To examine whether it has a protective effect in diabetic nephropathy like conventional ACE inhibitors which are eliminated via the kidney, a study was performed in streptozotocin-induced diabetic rats for 8 months. Male Wistar rats were divided into 4 groups (control rats, diabetic rats treated with temocapril at the doses of 5 mg/l or 15 mg/l of drinking water, and untreated diabetic rats). There was no significant difference in the blood glucose levels of the 3 diabetic groups. Administration of temocapril at both doses of 5 mg/l and 15 mg/l significantly reduced the blood pressure as well as the urinary excretion of albumin and N-acetyl-beta-D-glucosaminidase. However, significant suppression of glomerular basement membrane hypertrophy was only induced by treatment with temocapril at the dose of 15 mg/l. Elevated glomerular filtration rate and filtration fraction in diabetic rats were decreased by tempocapril at the dose of 15 mg/l, but not significantly. These results indicate that tempocapril has a protective effect on diabetic nephropathy like conventional ACE inhibitors.