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Biomedical subjects

M Imai

Publications and source records attributed to M Imai.

At least 613 records · Page 34Linked to original sources
PubMed1976

e antigen and anti-e in the serum of asymptomatic carrier mothers as indicators of positive and negative transmission of hepatitis B virus to their infants.

Testing of serum samples of 23 pregnant women who were asymptomatic carriers of hepatitis B surface antigen for e antigen and antibody to e with an immunodiffusion technic identified 10 mothers with e antigen and seven with e antibody. Their babies were tested for hepatitis B surface antigen in serum at intervals for more than 12 months. In all 10 babies born to e-antigen-positive mothers hepatitis B surface antigen developed and persisted through the observation period, and all 10 elder siblings of these newborn babies were found to be asymptomatic carriers. In remarkable contrast, all seven babies born to mothers positive for antibody to e escaped antigenemia, and none of their three elder siblings carried surface antigen. On the basis of these results, e antigen may be used as an indicator of transmission, and antibody to e as that of absence of transmission of hepatitis B virus from carrier mothers to children.

Carrier State↗
PubMed1976

Isolation and genetic characterization of the nitA mutants of Escherichia coli affecting the termination factor rho.

Taking advantage of the Spi (sensitivity to P2 interference) phenomenon, bacterial mutants seemingly resistant to phage lambdasusNnin5, but sensitive to phage lambdaspi, were isolated from a strain of E. coli K12 carrying no nonsense suppressor and lysogenic for P2. A class of these mutants, designated nitA (N-independent transcription), is described here. Upon infection of the nitA mutants with a trp transducing phage lambdasusN7N53ptrp46 which carries the E. coli trpE and D genes in the CIII-att region of the lambda genome, formation of anthranilate synthetase (ASase, a complex protein of trp E and D gene products) was clearly demonstrated. In contrast, no ASase formation was observed in the parent nitA+ strain under the same conditions. The synthesis is subject to "turn off" control, and is completely repressed by the CI repressor of phage lambda. The nitA cells lysogenic for lambdaCI857susN7N53 are killed by thermal induction much more efficiently than the parent cells lysogenic for the same phage. The nitA mutants support the growth of lambdasusN7N53byp much better than the parent. These results suggest that the nitA mutation permits the early leftward and rightward transcription of the lambda genome in the absence of the N gene product. On the E. coli genetic map, nitA is located between ilv and metE, nearer to ilv. The mutant allele is recessive to the wild-type allele. The present evidence, together with results of biochemical investigations to be reported, suggests that nitA is a gene specifying the transcription termination factor rho.

Chromosome Mapping↗
PubMed1976

Inhibition of intracellular multiplication of adenovirus by interaction between infected and uninfected cells.

The possibility that virus multiplication may be inhibited by interaction of infected cells with uninfected cells was tested by experiments, using human adenovirus type 12 (Ad12). Permissive human cells (human embryonic kidney-HEK,KB or HeLa) were infected and seeded on uninfected or infected "nonpermissive" cell (human embryonic lung=HEL) monolayers, and virus yields or proportions of viral antigen-synthesizing cells were compared with each other. Both the virus yields and the proportions of viral antigen-positive cells were not reduced significantly when seeded on infected HEL cells, while they seeded on uninfected HEL cells both of them were reduced remarkably, compared with the yield and the proportion of controls seeded on glass. Similar results were obtained regardless of the type of permissive cells, HEK, KB, or HeLa. Similar reduction of the yield was observed when seeded on HEL cells infected with Ad12 inactivated by heat or by antiserum, and partial reduction was observed when seeded on HEL cells infected with UV-inactivated Ad12, depending on the extent of UV dosis. These experiments showed that intracellular virus multiplication may be inhibited by interaction of infected cells with uninfected cells, and this may be due to the difference in the cell surface structure.

Adenoviruses, Human↗
PubMed1976

Hepatitis B antigen-associated deoxyribonucleic acid polymerase activity and e antigen/anti-e system.

Serum samples of 403 asymptomatic blood donors carrying hepatitis B surface antigen (HB5Ag) were concentrated threefold and tested for e antigen and antibody to e antigen (anti-e) by immunodiffusion. Hepatitis B antigen (HBAg)-associated deoxyribonucleic acid (DNA) polymerase activity was specifically determined by the difference in incorporation of [methyl-3H]thymidine 5' -triphosphate into DNA by an aliquot of centrifuged serum samples after it had been treated either with normal rabbit serum or with rabbit antibody to HBSAg. All of 58 serum samples containing e antigen revealed HBAg-associated DNA polymerase activity, whereas none of 96 samples containing anti-e did. In the remaining 249 samples in which neither e antigen nor anti-e was found, 62 showed specific DNA polymerase activity, although at lower levels than the samples containing e antigen.

Antibodies, Viral↗
PubMed1976

Mechanism of sodium and chloride transport in the thin ascending limb of Henle.

Our previous in vitro studies have disclosed that the thin ascending limb of Henle (tALH) possesses some unique membrane characteristics. In those studies we failed to demonstrated active transport of sodium chloride by the tALH, although it was shown that the isotopic permeability to sodium and chloride was unusually high. However, we did not examine the mechanisms by which the apparent high permeation of sodium chloride occurs. Thus the purpose of the present studies was to elucidate the mechanism of sodium chloride transport across the isolated tALH of the rabbit by conducting four different types of studies: (1) comparison of the observed chloride and sodium flux ratios to those predicted by Ussing's equation under imposed salt concentration gradients; (2) kinetic evaluation of chloride and sodium fluxes; (3) examination of the effect of bromide on the kinetics of chloride transport; and (4) experiments to test for the existence of exchange diffusion of chloride. In the first set of studies the predicted and the theoretical flux ratios of sodium were identical in those experiments in which sodium chloride was added either to the perfusate or to the bath. However, the observed chloride flux ratio, lumen-to-bath/bath-to-lumen, was significantly lower than that predicted from Ussing's equation when 100 mM sodium chloride was added to the bath. In the second set of experiments the apparent isotopic permeability for sodium and for chloride was measured under varying perfusate and bath NaCl concentrations. There was no statistical change in the apparent sodium permeability coefficient when the NaCl concentration was raised by varying increments from 85.5 to 309.5 mM. However, permeation of 36Cl decrease significantly with an increase in Cl from 73.6 to 598.6 mM. These events could be explained by a two component chloride transport process consisting of simple diffusion and a saturable facilitated diffusion process with a Vmax = 3.71 neq mm-1 min-1. In the third set of studies it was shown that bromide inhibits transport of chloride and that the magnitude of inhibition is dependent on chloride concentrations. The fourth set of studies ruled out the existence of exchange diffusion. In conclusion, these studies indicate that sodium transport across tALH is by simple passive diffusion, while chloride transport across tALH involves at least two mechanisms: (1) simple passive diffusion; and (2) a specific membrane interaction process (carrier-mediated) which is competitively inhibited by bromide.

Animals↗
PubMed1976

Methemoglobinemia induced by chlorphenamidine.

A 76-year old farmer ingested 100 g of chlorphenamidine (Galectron), a plant acaricle, for the purpose of suicide. Gastric lavage was performed and the patient survived. Methemoglobinemia was noted after emergency treatment and was still present at 20 hours after ingestion of the compound. The patient was lethargic for at least 50 hours. Moderate neutrophilic leukocytosis and kidney injury were observed.

Aged↗
PubMed1976

A case of alcaptonuria with fatal cardiovascular disturbance.

A case of alcaptonuria combined with aortic insufficiency was found in a 28-year-old male. The patient was palpitating at admission. The daily excretion of homogentisic acid was 2.0-6.0 g. Electrocardiography indicated atrial fibrillation and left ventricular hypertrophy with a ST-T change and right axis deviation. Cartilage tissues in the knee-joints showed no pigmentation. Vertebral X-ray revealed no calcification. The patient's history disclosed a family intermarriage in his grandparents. The patient's mother noticed the presence of black stains on diapers in his infancy and brown pigmentation on the skin and sclera in childhood. No kin had similar symptoms.

Adult↗
PubMed1976

Rapid determination of thyroxine binding proteins of human serum.

A simple method is described for determing thyroxine binding proteins in human serum by electrophoresis at pH 8.6, using cellulose acetate membrane as the supporting medium. The procedure had high reliability in sera of normal subjects, pregnant women and patients with decreased thyroxine binding capacity of thyroxine binding globulin.

Alpha-Globulins↗
PubMed1976

Association of dane particles with e antigen in the serum of asymptomatic carriers of hepatitis B surface antigen.

Asymptomatic carriers of hepatitis B surface antigen (HBsAg) were surveyed for serum e antigen (e Ag) and antibody to e (anti-e) by immunodiffusion. Seventeen serum samples containing e Ag and 17 containing anti-e, but with similar HBsAg titers, were tested for the presence of hepatitis B core antigen (HBcAg) by means of immune adherence hemagglutination method. HBcAg activity was detected in all of the samples containing e Ag, and the titer of HBcAg paralleled that of HBsAg in each serum. In remarkable contrast, no HBcAg activity was found in any of the serum samples containing anti-e. Dane particles were demonstrated in 14 of 17 serum samples with e Ag by electron microscopy, but in none of 17 with anti-e. Although both e Ag and HBcAg were closely associated with each other, the non-identity of e Ag and HBcAg was clearly demonstrated by a two-dimensional immunodiffusion test.

Antibodies, Viral↗
PubMed1976

Large-scale isolation of Dane particles from plasma containing hepatitis B antigen and deomnstration of circular double-stranded DNA molecule extruding directly from their cores.

A method was developed to isolate, on a large scale, Dane particles from five liters of pooled plasma of asymptomatic carriers of hepatitis B antigen. It involved three successive ultracentrifugation procedures; the final preparation was more than 98% pure in Dane particles. Purified Dane particles had the density of 1.23 to 1.24 g/cm3. The concentration of nucleic acids in the preparation containing purified Dane particles was too low to be detected either by chemical or by spectrophotometric method. However, a circular double-stranded DNA molecule extruding directly from the core of Dane particles was clearly demonstrated by elelctron microscopic observations. The cores of Dane particles (hepatitis B core antigen; HBCAg) were prepared by treating the Dane particle preparation with mercaptoethanol and Nonidet P-40. They were sufficient both in purity and amounts to allow the determination of antibody to HBCAg by an immune adherence hamagglutination method.

Animals↗
PubMed1975

Effect of polymyxin B on liposomal membranes derived from Escherichia coli lipids.

The specificity of the action of polymyxin B was studied using liposomes as a model membrane system. Liposomes prepared from total lipids of Gram-negative bacteria Escherichia coli, a mixture of purified E. coli phosphatidylethanolamine and cardiolipin and a mixture of phosphatidylethanolamine and phosphatidylglycerol, were extemely sensitive to polymyxin while those prepared from lipids of Gram-positive bacteria Streptococcus sanguis, lipids of sheep erythrocyte membranes, mixtures of egg lecithin and negatively charged amphiphatic molecules, were less sensitive to the action of the antibiotic. Cholesterol was shown to suppress the polymyxin-induced response in liposomes.

Cardiolipins↗
PubMed1975

Characteristics of salt and water transport in superficial and juxtamedullary straight segments of proximal tubules.

The purpose of the present studies was to characterize the nature of salt and water transport out of the superficial (SF) and juxtamedullary (JM) straight segments of rabbit proximal tubules as examined by in vitro microperfusion techniques. When the perfusate consisted of a solution simulating ultrafiltrate of plasma, there were no differences between SF and JM straight tubules in either net reabsorption of fluid (SF=0.47 nl/mm per min; JM=0.56 nl/mm per min) or in transtubular potential difference (PD) (SF=-2.1 mV; JM=-1.8 mV). Removal of glucose and alanine from the perfusate had no effect on the magnitude of the PD in either straight segment. Ouabain decreased both the net reabsorptive rates and the PD. Isosmolal replacement of NaCL by Na-cyclamate (a presumed impermeant anion) in the perfusate and the bath caused an increase in luminal negativity in both segments wheras similar substitution of NaCL by choline-CL (nontransported cation) changed the PD TO NEAR ZERO. These studies, therefore, suggest that sodium is transported out of the proximal straight tubules by an active noncoupled process that generates a PD (electrogenic process). When the perfusate consisted of a solution with a high chloride concentration (resulting from greater HCO3 than CI reabsorption in the proximal convoluted tubule), different PDs in SF and JM tubules were generated: SF=+1.6 plus or minus 0.2 mV; JM=-1.3 plus or minus 0.3 mV. This difference in PD was attributed to relative differences in Na and CI permeabilities in these two segments. Electrophysiological and isotopic estimates of the chloride to sodium permeability revealed that the SF tubule is about twice as permeant to chloride than to sodium whereas the JM tubules are approximately twice as permeant to sodium than to chloride. It is concluded that the mechanism of active sodium transport in the straight segment of proximal tubule differs from that of the convoluted segment and that both the SF and JM straight segments differ from each other with respect os sodium and chloride permeability.

Animals↗
PubMed1975

A functional comparison of the cortical collecting tubule and the distal convoluted tubule.

Electrical and permeability features of the distal convoluted tubule (DCT) and the cortical collecting tubule (CCT) were examined using the technique in which isolated segments of rabbit tubules were perfused in vitro. When rabbits were given a regular diet and tubules were perfused and bathed in artificial solutions simulating plasma ultrafiltrate, the potential difference (PD) was +3.7 plus or minus 1.9 mV in the CCT and -40.4 plus or minus 2.8 mV in the DCT. When rabbits were given a low sodium, high potassium diet plus i.m. deoxycorticosterone acetate (DOCA) (1 mg/kg per day), the PD in both the CCT (-30.8 plus or minus 3.9 mV) and the DCT (-33.8 plus or minus 5.5 mV) was negative. The PD in the CCT was quantitatively similar to that of diet plus DOCA when animals were given DOCA alone. The PD in both segments was inhibited by ouabain (10-minus 5 M) in the bath or by amiloride (10-minus 5 M) in the perfusate. Addition of vasopressin (200 muU/ml) to the bath caused a gradual decline of PD to zero in the CCT but failed to produce a potential response in the DCT. Osmotic water permeability was essentially zero in both segments in the absence of vasopressin. After addition of the vasopressin to the bath, osmotic water permeability in the DCT remained zero but increased to 71.9 plus or minus 25.5 X 10-minus 7 cm/s per atm in the CCT. We conclude that both segments are similar in that each possesses an electrogenic transport process but that these segments differ in that: (a) the CCT requires either exogenous or endogenous mineralocorticoid to maintain a maximal negative PD, whereas the PD in the DCT appears to be independent of mineralocorticoid effect; and (b) the CCT responds to vasopressin with a marked rise in water permeability, whereas the DCT is impermeable to water before and after addition of vasopressin.

Adrenal Cortex Hormones↗
PubMed1975

[Myocardial sarcoidosis--pathological studies on 7 autopsy cases with particular reference to histological variations].

The present report consists of seven autopsy cases of myocardial sarcoidosis terminating in death 1 month to 5 years after the onset of symptoms. Histologically, they were classified into the following 4 types: a) diffuse nonspecific granulation, b) specific granuloma with giant cells, c) diffuse fibrosis with giant cells, and d) nonspecific fibrosis. Types a) and b) demonstrate active changes, while c) and d) are sequelae of active inflammation. Morphological changes of sarcoidosis were found not only in myocardium but also in both pericardium and endocardium. Although no final conclusions could be obtained as to whether the giant cells appearing in myocardium were of mesenchymal or myogenic origin, the authors favor the latter concept. Changes compatible to sarcoidosis found in other organs in acute cases were scarce and old. On the contrary, more active and variable changes were encountered in protracted cases. The authors consider giant cell myocarditis to be one type of sarcoidosis occurring in the heart.

Adult↗