The possible role of remnant-like particles as a risk factor for sudden cardiac death

Postmortem plasma lipid and lipoprotein levels were analyzed in two groups of Japanese subjects who died suddenly and unexpectedly due to cardiac (n = 93) or non-cardiac (n = 26) causes. No individuals in either group had a significant medical or cardiac history. In this study, we measured plasma total cholesterol, triglycerides, VLDL-cholesterol, LDL-cholesterol, HDL-cholesterol, and especially triglyceride-rich lipoprotein remnants. Triglyceride and apo E-rich remnant-like particles (RLP) were studied as a possible risk factor for sudden cardiac death in relation to the progression of coronary atherosclerosis. The receiver-operating characteristic curve (ROC) analysis showed that RLP-TG was the most significant risk factor for sudden cardiac death among the lipids and lipoproteins and RLP-C was the best predictor for coronary atherosclerosis. HDL-C and LDL-C levels were within normal limits in the majority of the cases and did not appear to relate to the sudden cardiac death. Apo E phenotyping was performed for the detection of the genetic background in the lipid metabolism. The frequency of the Apo E3/3 (wild type) phenotype, which closely relates with the remnant metabolism, was significantly reduced in the sudden cardiac death group. Our study on the postmortem plasma lipid analysis suggested that RLP-C and RLP-TG are the best risk predictor for coronary atherosclerosis and sudden cardiac death, respectively.

Studies on the N-[(trans-4-isopropylcyclohexyl)-carbonyl]-D-phenylalanin e (A-4166)receptor in HIT T-15 cells. Displacement of [3H]glibenclamide

A-4166 is a new type of oral hypoglycemic agent that does not contain a sulfonylurea moiety. To clarify the mechanism of insulin secretion by A-4166, a specific receptor for A-4166 was investigated in a hamster pancreatic beta cell line (HIT T-15), using [3H]A-4166 or [3H]glibenclamide as a ligand. The saturation binding of [3H]A-4166 to HIT cell membranes was not observed up to 10 microM. In the displacement study, unlabeled A-4166 inhibited [3H]A-4166 binding to HIT cell membranes, but glibenclamide did not. On the other hand, A-4166 inhibited [3H]glibenclamide binding to the sulfonylurea receptor (Ki = 248 nM). A-4166 inhibited 86Rb efflux from HIT cells (IC50 = 350 nM). The EC50 for insulin secretion by A-4166 was 20 microM in HIT cells when they were incubated for 30 min in Krebs-Ringer bicarbonate buffer containing 16 mM HEPES supplemented with 5 mg/mL BSA in the absence of glucose. These data demonstrate the possibility of the presence of two kinds of binding sites for A-4166: one of them is the sulfonylurea receptor, and the other might be a binding site specific for A-4166.

AVASCULAR NECROSIS AND THE PAVLIK HARNESS

We analysed the incidence of avascular necrosis in 101 hips of 90 infants with congenital dislocation treated with the Pavlik harness and followed up for more than one year. Using ultrasonography in the flexed-abducted position the hips were classified as type A when the femoral head was displaced posteriorly, but within the socket and making contact with the posterior inner wall of the acetabulum; type B when it was in contact with the posterior margin of the acetabulum, with its centre at this level or anterior to it; and type C when it was displaced out of the socket, with its centre posterior to the posterior rim of the acetabulum.

Eighty-seven hips were reduced by the harness (86%), and seven of these developed avascular necrosis (8%). All 69 hips with type-A dislocation were reduced, and only one (1.4%) showed slight avascular necrosis. Eighteen (78.3%) of 23 hips with type-B dislocation were reduced, and six developed avascular necrosis (33.3%). In one hip, the femoral head was severely damaged. None of the nine hips with type-C dislocation was reduced in the harness.

We conclude that the Pavlik harness is indicated for type-A, but not for type-B or type-C dislocations.

Avascular necrosis and the Pavlik harness. The incidence of avascular necrosis in three types of congenital dislocation of the hip as classified by ultrasound

We analysed the incidence of avascular necrosis in 101 hips of 90 infants with congenital dislocation treated with Pavlik harness and followed up for more than one year. Using ultrasonography in the flexed-abducted position the hips were classified as type A when the femora head was displaced posteriorly, but within the socket and making contact with the posterior inner wall of the acetabulum; type B when it was in contact with the posterior margin of the acetabulum, with its centre at this level or anterior to it; and type C when it was displaced out of the socket, with its centre posterior to the posterior rim of the acetabulum. Eighty-seven hips were reduced by the harness (86%), and seven of these developed avascular necrosis (8%). All 69 hips with type-A dislocation were reduced and only one (1.4%) showed slight avascular necrosis. Eighteen (78.3%) of 23 hips with type-B dislocation were reduced, and six developed avascular necrosis (33.3%). In one hip, the femoral head was severely damaged. None of the nine hips with type-C dislocation was reduced in the harness. We concluded that the Pavlik harness is indicated for type-A but not for type-B or type-C dislocations.

Treatment of multiple early gastric cancer

To investigate the treatment of multiple early gastric cancer, 82 cases were compared with 829 single early gastric cancers. Univariate analyses with respect to eight clinicopathological factors--age, sex, family history of gastric cancer, macroscopic appearance, histologic type, depth of tumor invasion, tumor location, and lymph node metastasis--were performed. Age, male sex, elevated and differentiated-type tumors, frequent occurrence in the lower third, and mucosal cancers were correlated significantly with multiple early gastric cancer. However, there was no significant difference in the frequency of node involvement. Multiple early gastric cancer, limited to the mucosal layer, was not associated with node involvement. Therefore, endoscopic mucosal resection may be feasible for the treatment of multiple early gastric cancer when there is no evidence of submucosal invasion in any of the lesions and none exceed 2.0 cm in diameter. Upon examination of the long-term results for patients with multiple early gastric cancer, two (3.0%, 2/66) had died of recurrence due to hematogenous spread, and one (1.9%, 1/52) had developed cancer of the remnant stomach. Other primary malignancies were observed in 12 patients (18.2%, 12/66). In particular, lung cancer was the major neoplasm occurring after gastrectomy. These results suggest the importance of systemic surveillance for the detection of other malignancies as well as cancer of the remnant stomach and recurrence after gastrectomy for multiple early gastric cancer.

Stability and spontaneous production of blood cyanide during heating

To investigate the effects of heat on blood cyanide concentrations, in vitro experiments were performed using a headspace gas chromatographic method. Cyanide concentrations were determined for solutions of human hemoglobin (Hb) at neutrality, and for blood which was sealed in a vial and incubated at 25, 50, 63, 75 and 90 degrees C for 1 h. Spontaneous cyanide production was also measured. Nearly all of the added cyanide was recovered in both the Hb and for blood samples which were heated below 63 degrees C. Cyanide recovery in Hb decreased in a temperature-dependent manner at temperatures above 75 degrees C, and more than half of the recovered cyanide was found to be in the free form. In contrast, cyanide in blood disappeared more rapidly, and a major portion of it existed in the bound form. Cyanide concentrations in Hb solutions which were heated at 90 degrees C dropped in the two phases; a rapid initial phase, followed by a slower process. Spontaneous cyanide production was observed at temperatures above 50 degrees C for Hb and above 63 degrees C for blood. Under optimal conditions (75 degrees C heating), about 0.2 mmol of cyanide was produced per mol heme of Hb.

Prediction of reduction in developmental dysplasia of the hip by magnetic resonance imaging

The acetabular rim of 33 hips in 29 patients with developmental dysplasia of the hip was evaluated using magnetic resonance imaging (MRI). The hips were classified into the following three groups according to the shape of the acetabular rim: 12 hips with sharp acetabular rim (group 1), 13 hips with dysplastic and round acetabular rim (group 2), and eight hips with inverted acetabular rim (group 3). The position of the femoral head with the hip flexed and abducted was also recorded, according to the criteria proposed by Suzuki. They were all treated initially with the Pavlik harness. All group 1 hips were successfully reduced with the Pavlik harness, whereas in group 2 hips, all but three hips were reduced. In all group 3 hips, reduction was not successful. MRI provided useful information regarding the probability of reduction with the Pavlik harness.

An autopsy case of traumatic sinus thrombosis

A 38-year-old male slipped accidentally and fell from a height of 4.6 m, and was admitted to a hospital. A radiograph indicated a linear fracture of the parietal bone across the sagittal sutura, and a computed tomography scan of the head showed severe subdural hematoma on both parietal sides, so an operation was performed to remove the hematoma. Five hours after the operation, brain death due to a cerebral herniation occurred, and he died six days later. Autopsy revealed a linear fracture of the parietal bones, which crossed obliquely the sagittal sutura. A slightly lacerated wound of the dura mater was seen on the sagittal sutura, from where the latter half of that point to the left and right transverse sinuses were occluded completely with thrombosis. The brain was markedly swollen. From these findings, the victim was considered to have died from acute cerebral swelling due to traumatic thrombosis of the superior sagittal sinus.

A 20-kDa protein in human seminal plasma that is identical to gross cystic disease fluid protein 15 and prolactin-inducible protein

A new method is described for isolating the 20-kDa protein, which used to be purified using an actin-immobilized column from human seminal plasma. This method employed ion-exchange column chromatography and isoelectric focusing separation. The level of seminal protein was determined by sandwich ELISA to be 1.06 +/- 0.27 mg/mL (mean +/- SD, n = 8). Its cDNA was cloned from a human salivary gland cDNA library by immunoscreening. The 553-nucleotide sequence included the 5' untranslated region and extended to the poly(A) tail. It encoded a protein of 118 amino acid residues in addition to a signal sequence of 28 residues. This sequence was identical to those of gross cystic disease fluid protein 15 and prolactin-inducible protein cDNAs. Northern blotting revealed the common expression in the submandibular gland and seminal vesicle. An immunohistochemical study in paraffin-embedded tissues from human male sex organs also indicated that the 20-kDa protein is mainly produced in the seminal vesicle.

Reverse transcription-polymerase chain reaction detection and sequence analysis of small round-structured viruses in Japan

Between 1985 and 1995, mass outbreaks of acute gastroenteritis caused by small round-structured virus (SRSV), occurred in eight prefectures in Japan. Fecal samples from 59 patients ill during these outbreaks were recently examined in our laboratory by electron microscopy (EM) and by reverse transcription-polymerase chain reaction (RT-PCR). For RT-PCR, we prepared two sets of primers, a set corresponding to the polymerase region of open reading frame 1 (ORF-1) and a set corresponding to the capsid region of ORF-2 of Norwalk virus (NV). The SRSV nucleic acid detection rate with these primers was more than double that achieved with EM. Most samples found by EM to contain virus particles were also positive by PCR. When the two sets of primers were used separately, the virus detection rate differed depending on the primer used, suggesting that the viral strains examined were not genetically not homogeneous. We then selected nine strains of the virus, cloned their PCR products and analyzed their base sequences. The base sequences of these strains were compared with those of reference strains including prototype NV and Snow Mountain agent (SMA). This comparison yielded the following findings: (1) SRSVs that cause mass outbreaks of gastroenteritis in Japan are genetically variable; (2) SRSV strains that are genetically similar to SMA and SRSV-OTH 25/89/J(OTH25) are dominant in Japan, but strains similar to NV are also present in this country; and (3) a strain (MI1/94) which is genetically identical to Southampton virus (SHV) was detected. Detection of SRSV using sensitive RT-PCR and analysis of the sequences of the amplification products seems to provide a useful means of studying the molecular epidemiology of SRSV.

Stimulating activity of A-4166 on insulin release in in situ hamster pancreatic perfusion

Using the in situ hamster pancreatic perfusion system, the stimulating action of A-4166 on insulin release was examined in comparison with that of glibenclamide. Both antidiabetic agents stimulated insulin release, but its onset by A-4166 was faster than that by glibenclamide. In the presence of a basal glucose concentration (3 mmol/l), insulin releases induced by A-4166 and glibenclamide were inhibited by preexisting diazoxide. At higher glucose concentrations (5-16.7 mmol/l), however, A-4166 was able to reverse the inhibitory effect of diazoxide on the first and second phases of insulin release, while glibenclamide did not reverse the first-phase release. On the other hand, in the presence of 16.7 mmol/l of glucose A-4166 completely reversed the inhibitory action of diazoxide added simultaneously, but glibenclamide reversed it only partially. In the presence of 8 mmol/l of glucose, the stimulating action of A-4166 and glibenclamide on insulin release was hardly affected by inhibitors of ATP production. These results indicate that the stimulating action of A-4166 on insulin release is different from glibenclamide in response to the inhibitory action of diazoxide. These results also suggest that A-4166 is an effective agent for release of insulin by acting on the KATP channel, especially under an impaired function of pancreatic B cells.

Oxidative conversion of thiocyanate to cyanide by oxyhemoglobin during acid denaturation

Human oxyhemoglobin (Hb-O2) converts thiocyanate to cyanide under acidic conditions, in a hemoglobin and thiocyanate concentration-dependent manner. Other naturally occurring hemoglobin derivatives and hematin did not result in cyanide-producing activity. Pre-denaturation completely destroyed cyanide production. In the presence of 10% phosphoric acid, 12 microM cyanide was produced by 1 mM Hb-O2 (per heme) and 1 mM thiocyanate. This conversion was observed over a wide range of acidic pH levels at 50 degrees C, with an optimal pH of 4. The production of cyanide under strong acidic conditions was completed within 1 s, while under weak acidic conditions (pH approximately 5) the production gradually increased for half an hour. Under both conditions, the time course for cyanide production coincided with the disappearance of this converting activity. Thiocyanate conversion by acidified Hb-O2 was completely suppressed by the addition of ascorbic acid, significantly suppressed by superoxide anion radical (O2-) scavengers or thiourea, but not effected by scavengers of hydroxyl radical, singlet oxygen, and protein radical. In addition to acidification, other processes for denaturation of Hb-O2 resulted in detectable production of cyanide, e.g., heating, extraction by organic solvents, and incubation with denaturating or oxidative reagents. These data suggest that O2- generated during Hb-O2 denaturation and also a hydroperoxyl radical converted under acidic conditions are the oxidizing species that convert thiocyanate to cyanide.

Characterization of a mutation responsible for an alkali-sensitive mutant, 18224, of alkaliphilic Bacillus sp. strain C-125

An alkali-sensitive mutant, 18224, of the alkaliphilic Bacillus sp. strain C-125 was characterized. The nucleotide sequence of the PvuI-NlaIV DNA fragment that recovers the alkaliphily of 18224 has been cloned from the mutant and sequenced. Comparison of the nucleotide sequences of the corresponding regions found a G to A substitution in the mutant. The mutation resulted in an amino acid substitution from 82Gly to Glu of the putative ORF3 product, which consisted a gene cluster of at least four tandemly located open reading frames. The ORF3 product was deduced to be an 112 amino acid polypeptide with hydrophobic properties, which was expressed using an in vitro translation system.

Characterization of insulin-dependent diabetes mellitus induced by a new variant (DK-27) of encephalomyocarditis virus in DBA/2 mice

A murine diabetes mellitus induced with a new diabetogenic variant (DK-27) which we isolated from the M variant of the encephalomyocarditis (EMC) virus was characterized. Male DBA/2 mice (9.5 weeks old) were infected with various infectious doses of DK-27 intraperitoneally. Blood glucose and insulin levels were examined in association with the viral replication. Pancreatic pathology and hormone contents and stable hemoglobin A1c (St-A1c) levels were also examined on the final day of observation (35 days of post-infection). In infected mice, blood glucose levels rapidly elevated at 72 hr, slightly decreased between 7 and 10 days and finally became sustained hyperglycemia. On the other hand, blood insulin levels elevated at 48 hr, promptly decreased, and subsequently became sustained hypoinsulinemia. Viral replication in pancreases reached the highest titers at 48 hr and rapidly disappeared with all infectious doses used. Pancreatic insulin contents in infected mice were not detectable, and glucagon contents were not affected. In pathological examination, atrophy of islets and marked diminution of B-cells were observed, and A-cells occupied the major part of an infected islet. St-A1c levels reflected lasting hyperglycemia. These findings show that DK-27 causes insulin-dependent diabetes mellitus by the specific and direct destruction of pancreatic B-cells in susceptible mice. Such a diabetic model mouse will be useful for therapeutic studies.

Radical cation intermediates in N-dealkylation reactions

1. A number of mechanistic possibilities exist for P450-catalysed N-dealkylation and have been considered over the years, including C- and N-hydroxylation and sequential electron transfer (SET). With peroxidases the evidence strongly favours SET and free radicals can be detected. Any mechanism must account for lack of incorporation of label from H218O into product by P450s and the high kinetic deuterium isotope effects that are seen in N-dealkylation reactions catalysed by peroxidases but not P450s. 2. Several lines of evidence support a role for SET in P450 amine oxidations, including Hammett analysis, products of dihydropyridine oxidations, and products of mechanism-based inhibition by strained cycloalkylamines. 3. The hypothesis was considered that the P450s act via base catalysis to deprotonate the aminium radical generated by SET, since the pKa has been estimated to be approximately 9. Dihydropyridine aminium radicals have low pKa (< 4) and are generally considered to have considerable kinetic acidity. None of the haemoproteins under consideration (including the peroxidases and haemoglobin) showed high kinetic hydrogen isotope effects for the oxidation of [4-2H]- or [4-3H]-labelled 1,4-dihydropyridines. These results are consonant with the view that P450s catalyse the deprotonation of N,N-dialkylaniline aminium radicals. 4. Since low isotope effects were seen with biomimetic metalloporphyrin models as well as P450s, the deprotonation is attributed to the (FeO)2+ entity, expected to be a strong base, and not the apoprotein. Thus, the FeO moiety of peroxidases is shielded, consistent with evidence by others that SET occurs through the porphyrin edge. Both P450s and peroxidases catalysed the oxidative N-demethylation of aminopyrine and N,N-dimethylaminothioanisole; however, only the peroxidases generated the stable coloured aminium radicals. 5. The rates of N-demethylation of variously para-substituted N,N-dimethylanilines can be used to undertake Hammett or Marcus analysis. The former yields rho = -0.6 and the latter an apparent E1/2 of approximately 1.8 for the formal (FeO)3+ entity of P4502B1. 6. Even in the oxidation of N,N-dialkylanilines, a finite rate of N-oxidation is seen (approximately 0.1% of N-dealkylation). The simplest paradigm has N-oxygenation and N-dealkylation both proceeding from a common aminium radical intermediate.

Molecular cloning of a 46-kilodalton surface antigen (P46) gene from Mycoplasma hyopneumoniae: direct evidence of CGG codon usage for arginine

The DNA sequence of the gene encoding the early and specific 46-kDa surface antigen (P46) of Mycoplasma hyopneumoniae has been determined. The P46 gene, encoding a putative lipoprotein, contained three TGA codons and a single CGG codon in a 1,257-bp open reading frame. Edman degradation of peptide fragments showed that at least one TGA codon encodes tryptophan and that the CGG codon, which has been reported to be nonsense or unassigned in other mycoplasmas, is used for arginine in M. hyopneumoniae.

The relationship of macroscopic shape of superficial esophageal carcinoma to depth of invasion and regional lymph node metastasis

BACKGROUND

There has been considerable controversy with regard to surgical strategies for the treatment of superficial esophageal carcinoma, which is characterized by tumor confined within the epithelium (EP), muscularis mucosae (MM), or submucosa (SM). The relationships among macroscopic shape, depth of invasion, and lymph node involvement in superficial tumors were investigated to devise therapeutic strategies for patients with such disease.

METHODS

Thirty-three patients with superficial primary esophageal cancer underwent esophagectomy with regional lymph node dissection (3 EP, 6 MM, and 24 SM). Tumors were divided into two types according to macroscopic characteristics: (1) tumors with elevated components and (2) flat or depressed tumors without an elevated component.

RESULTS

Tumors with an elevated component (n = 19) showed invasion of the deep layer, and a high incidence of lymph node metastasis. Conversely, tumors without an elevated component (n = 14) showed varied depths of invasion, and, with one exception, had no lymph node involvement.

CONCLUSIONS

The existence of an elevated component in superficial esophageal cancer is an important macroscopic feature suggesting submucosal invasion and a high probability of lymph node involvement. More intensive treatment should be adopted for such tumors, whereas localized resection may be feasible for tumors without an elevated component.

Effects of D-phenylalanine-derivative hypoglycemic agent A-4166 on pancreatic alpha- and beta-cells: comparative study with glibenclamide

We have reported that N-[(trans-4-isopropyl-cyclohexyl)-carbonyl]-D-phenylalanine (A-4166) stimulates insulin secretion in animal studies. To further elucidate the mechanisms underlying the actions of this agent, we investigated the effects of A-4166 on insulin and glucagon secretion with or without diazoxide, an ATP-sensitive potassium channel opener, using isolated perfused rat pancreas preparations, and compared the results with those of glibenclamide. Both 30 mumol/l A-4166 and 3 mumol/l glibenclamide significantly stimulated insulin secretion and reduced glucagon secretion to similar levels at a glucose concentration of 5.6 mmol/l (p < 0.01 for both vs. basal levels). After infusion of A-4166 was stopped, insulin levels promptly returned to the basal values, while insulin levels increased further even after discontinuation of glibenclamide. Furthermore, 100 mumol/l diazoxide significantly inhibited the insulin-stimulatory effects of both 30 mumol/l A-4166 and 3 mumol/l glibenclamide (p < 0.05 and p < 0.01, respectively). However, the effects of diazoxide on glucagon secretion differed between the two groups; 30 mumol/l A-4166 produced a transient increase in glucagon secretion (p < 0.05 vs. basal levels) but 3 mumol/l glibenclamide suppressed glucagon secretion further (p < 0.01 vs. without diazoxide) with concomitant administration of 100 mumol/l diazoxide. These findings suggest that A-4166 directly stimulates insulin secretion, at least in part, through mechanisms resembling those of sulfonylurea, but exerts different effect on glucagon secretion in isolated perfused rat pancreas.

Recombinant 46-kilodalton surface antigen (P46) of Mycoplasma hyopneumoniae expressed in Escherichia coli can be used for early specific diagnosis of mycoplasmal pneumonia of swine by enzyme-linked immunosorbent assay

The 46-kDa surface antigen (P46) is the early and species-specific immunogenic protein of Mycoplasma hyopneumoniae. Three TGA codons encoding tryptophan in the P46 gene were replaced with TGG by an in vitro mutagenesis technique. The mutated P46 gene was expressed in Escherichia coli by using the chelating peptide tag system. The purified recombinant P46 was successfully used in an enzyme-linked immunosorbent assay for detection of antibodies against M. hyopneumoniae in swine serum. It did not cross-react with sera from swine infected with Mycoplasma flocculate, Mycoplasma hyorhinis, or Mycoplasma hyosynoviae. With this method, mycoplasmal pneumonia of swine was detectable within 2 weeks after infection.

Arthroscopy in 19 children with Perthes' disease. Pathologic changes of the synovium and the joint surface

Arthroscopy of the hip joint was performed in 19 children with Legg-Calvé-Perthes' disease. Proliferation of the synovium was pronounced both in the acetabular fossa and over the inner wall of the capsule. Hypervascularity was seen on the acetabular labrum in every stage of the disease. Microscopically, hyperplasia of the synovial lining cells was observed, but inflammatory changes in the synovial tissue were inconspicuous in the early stage of the disease. Although hypertrophy of the endothelial cells of the vessels was seen in the late stage of the disease, it was not distinct in the initial or fragmentation stages. Joint pain improved after irrigation during arthroscopy.

Oligonucleotide probes for Bordetella bronchiseptica based on 16S ribosomal RNA sequences

Bordetella bronchiseptica 16S ribosomal RNA (rRNA) gene was cloned and identified. On the basis of information from computer-assisted sequence comparison of the B. bronchiseptica 16S RRNA sequences with that of other bacterial species, we constructed B. bronchiseptica-specific oligonucleotide probes complementary to variable regions in the 16S rRNA molecule. Specificity of these 32P-labeled oligo-nucleotide probes was tested in a RNA/DNA hybridization with B. bronchiseptica strains and other bacterial strains. Probe BB4 was more specific than three other oligonucleotide probes. This probe BB4 was sensitive enough to be able to detect 10(4) bacterial cells.

Characterization of a gene responsible for the Na+/H+ antiporter system of alkalophilic Bacillus species strain C-125

An alkali-sensitive mutant, 38154, of the alkalophilic Bacillus sp. strain C-125 could not grow at an alkaline pH. The nucleotide sequence of a 3.7 kb parental DNA fragment that recovers the growth of 38154 at alkaline pH has four open reading frames (ORF1-4). By subcloning the fragment, we demonstrated that a 0.25 kb DNA region is responsible for the recovery. Direct sequencing of the mutant's corresponding region revealed a G to A substitution. The mutation resulted in an amino acid substitution from Gly-393 to Arg of the putative ORF1 product, which was deduced to be an 804-amino-acid polypeptide with a molecular weight of 89,070. The N-terminal part of the putative ORF1 product showed amino acid similarity to those of the chain-5 products of eukaryotic NADH quinone oxidoreductases. Membrane vesicles prepared from 38154 did not show membrane potential (delta psi)-driven Na+/H+ antiporter activity. Antiporter activity was resumed by introducing a parental DNA fragment which recovered the mutant's alkalophily. These results indicate that the mutation in 38154 affects, either directly or indirectly, the electrogenic Na+/H+ antiporter activity. This is the first report which shows that a gene responsible for the Na+/H+ antiporter system is important in the alkalophily of alkalophilic microorganisms.

Sequence diversity of small, round-structured viruses in the Norwalk virus group

We have determined the nucleotide sequences of a highly conserved region of the RNA-dependent RNA polymerase of the prototype Snow Mountain agent (SMA) and of four other small, round-structured viruses (antigenically Norwalk virus [NV]-like or SMA-like) following reverse transcription-PCR amplification of viral RNA obtained from human stools. The stool samples were either from volunteers administered SMA or from sporadic cases and outbreaks of gastroenteritis that occurred in Japan and the United Kingdom between 1984 and 1992. The GLPSG and YGDD RNA polymerase motifs were in the proper locations in the sequences of the five SRSVs, but each sequence was distinct from the 8FIIa prototype NV sequence and from each other. Analysis of the sequences and reactivities in a new NV antigen enzyme-linked immunosorbent assay showed that the five viruses could be divided into two groups (serogroups) with NV and SMA, respectively, being the prototypes. The sequences of the capsid region and a nonstructural region (2C) were determined from one strain from each group. One virus (SRSV-KY-89/89/J), isolated in Japan and antigenically similar to the prototype NV (isolated 21 years earlier in Ohio), showed a remarkable level of sequence similarity to NV. KY-89 and the 8FIIa NV showed 87.2% nucleotide similarity over 2,516 continuous nucleotides amounting to 96 to 98.9% amino acid similarity in three distinct domains in two open reading frames. Between the prototype SMA and NV, the polymerase region showed 63% nucleotide and 59% amino acid similarity, respectively. Two other antigenically SMA-like isolates (SRSV-925/92/UK and SRSV-OTH-25/89/J), from the United Kingdom and Japan, showed 80% nucleotide and 88 to 92% amino acid similarity in the polymerase region to the prototype SMA isolated 16 and 13 years earlier in the United States. The capsid region of the antigenically SMA-like OTH-25 virus showed 53% nucleotide and 65% amino acid similarity to the prototype NV capsid region. Domains of sequence diversity and conversation were identified within the capsid protein of these two distinct prototype serotypes of virus. These results indicate that NV-like and SMA-like agents are still circulating, and sequence comparisons will be useful to identify and classify distinct viruses in the NV group.