PubMed Health⌕ Search

Biomedical subjects

K Kera

Publications and source records attributed to K Kera.

16 recordsLinked to original sources
PubMed1991

Neural rosette formation within in vitro spheroids of a clonal human teratocarcinoma cell line, PA-1/NR: role of extracellular matrix components in the morphogenesis.

From the human teratocarcinoma-derived cell line PA-1, we established a clonal line, PA-1/NR, that stably produced a distinct cellular arrangement of neural rosettes when cultured as in vitro multicellular spheroids for 3 weeks. On immunofluorescence staining and fluorescence-activated cell sorter analyses, PA-1/NR cells in monolayer expressed the neuroectoderm-associated antigens HNK-1, NC-1, and A2B5 and the neuroblastoma-associated antigens KP-NAC8 and KP-NAC10 but lacked human embryonal carcinoma antigens, SSEA-3 or K21 antigen. Here, we investigated the developmental process of rosette formation with respect to morphological features, distribution of mitotic cells, and expression of multiple lineage-related markers and extracellular matrix (ECM) components. Ultrastructural examination of these rosettes disclosed a well-defined cavity radially surrounded by wedge-shaped or pseudostratified cells, apical microvilli and junctional complexes, and basal laminae and collagen fibrils at their basal surface. In these rosettes, many proliferating cells were detected by the immunohistochemical staining of cells incorporating bromodeoxyuridine. PA-1/NR spheroids consistently displayed neuron-specific enolase, S-100 protein, and vimentin but not glial fibrillary acidic protein, neurofilament proteins, or myelin basic protein. The rosette formation accompanied a strikingly polarized and overlapped deposition of ECM components including tenascin-carrying HNK-1 epitopes, laminin, type IV collagen, heparan, and chondroitin sulfate proteoglycans. Immunoblotting analyses showed that laminin B1 and B2 chains were constitutively expressed, whereas a fully assembled form of laminin and type IV collagen appeared only after spheroid development, suggesting that these ECM components play a morphogenetically important role in rosette formation. Close similarities between these rosettes and the neural tube of humans and experimental animals in the morphogenetic process and ECM formation lead us to propose that the PA-1/NR spheroids provide an in vitro model for the study of the earliest stage of human neurogenesis.

Antibodies↗
PubMed1990

Induction of human embryonal carcinoma cell differentiation using N,N'-hexamethylene bisacetamide in vitro.

Morphological differentiation of a pluripotent cloned human embryonal carcinoma cell line, NEC 14, was induced with the addition of N,N'-hexamethylene bisacetamide (10(-2) M) for 3 days in vitro. Once differentiated, the NEC 14 cells temporarily lost both their proliferative capacity in vitro and their tumorigenic potential in the nude mouse. When culture was continued, the differentiated derivatives occasionally began to proliferate 4 weeks after the removal of the inducer, but the loss of tumorigenic potential was not recovered. Besides morphology and loss of proliferative and tumorigenic potential, the differentiated derivatives expressed both differentiation markers, HLA antigens, and intermediate filaments. This system is useful in the selection of differentiation modifiers in cancer therapy.

Acetamides↗
PubMed1982

Survival of and hepatoma development in patients with liver cirrhosis.

A follow-up study was made on 75 patients with liver cirrhosis. The patients were divided into 5 groups (discontinued alcoholic group, continued alcoholic group, hepatitis B group, male non-alcoholic non-hepatitis B group, and female non-alcoholic non-hepatitis B group). Hepatoma developed in 50% of the hepatitis B group, but in 1-9% of the other 4 groups. Abstinence did not accelerate the development of hepatoma. As for survival after onset of liver cirrhosis, the 1-4-year survival of the female non-alcoholic non-hepatitis B group and the final (8-year) survival of the hepatitis B group appeared to be lower than that of the other groups. Though the survival of the discontinued alcoholic group was seemingly higher that that of the continued alcoholic group, the difference was small and not significant.

Carcinoma, Hepatocellular↗
PubMed1979

Hepatitis B antigens and antibodies in asymptomatic carriers and in chronic liver diseases.

88% of asymptomatic hepatitis B surface antigen (HBsAg) carriers and 97% of HBsAg positive patients with chronic hepatitis or non-alcoholic liver cirrhosis showed high titers of antibody to hepatitis B core antigen (anti-HBc). A high titer of anti-HBc, thus suggested to be an indicator of persistent hepatitis B virus infection, was found rarely in seronegative patients with chronic hepatitis, non-alcoholic cirrhosis, or alcoholic liver diseases. It was not revealed in idiopathic portal hypertension or Budd-Chiari syndrome. In asymptomatic HBsAg carriers of 20--29 years of age, hepatitis B e-antigen (HBeAg) was significantly more frequently found in males than in females. There were differences in sex ratio, age, and history of blood transfusion between B type and non-B type of chronic hepatitis and non-alcoholic liver cirrhosis.

Adult↗
PubMed1979

Alcoholic liver disease in women.

In 1972-1977, 130 patients with alcoholic liver disease (123 men and 7 women) were admitted. A half of the women had occupations which are related with alcohol consumption and a half were housewives. Daily consumption of alcohol in the women was the same as in the men. Duration of excessive drinking was 11.4 years in the women and 17.1 years in the men, but the difference was not statistically significant. Though the difference of the incidence of alcoholic hepatitis in the women (57%) and in the men (27%) was not statistically significant, frequency of ascites was significantly higher in the women (43%) than in the men (7%). Women seem to be more susceptible to severe form of alcoholic liver damage.

Adult↗
PubMed1978

The effects of trichothecene toxins on the Bursa of Fabricius in day-old chicks.

The effects of T-2 toxin, Fusarenon X (FX), and Nivalenol (NV) on the bursa of Fabricius in the day-old chick were examined. After injections of 5 mg/kg of the mycotoxins into the residual yolk sac, cellular injury was limited at first to the smaller epithelial cells with coarse microvilli, which were located in the central portion of the follicle-associated epithelium. Subsequently necrosis spread out to the periphery. Degeneration and necrosis followed in the lymphoid cells in the lymphoid follicles. The other epithelial components in the follicle were relatively resistant to the mycotoxins. Both FX and NV were less potent than T-2 toxin, although the effects on the bursa of Fabricius were essentially the same. These findings suggest that the follicle-associated epithelium is clearly distinguished from other epithelial components in the bursa of Fabricius in day-old chicks.

Animals↗
PubMed1977

Difference of hepatic circulation between alcoholic and non-alcoholic hepatic cirrhosis.

Comparisons were made of hepatic circulation between alcoholic and non-alcoholic cirrhosis. The wedged hepatic venous pressure and per cent intrahepatic shunt measured by the method of continuous infusion of D-galactose-1-14C were similarly markedly increased. On the other hand, the wedged hepatic venography showed the main portal trunk and extrahepatic collaterals, namely, the tendency of reverse or stagnant portal flow, more frequently in alcoholic cirrhosis than in non-alcoholic cirrhosis. The nodules shown by slow low-pressure hepatic sinusoidography were larger in non-alcoholic cirrhosis than in alcoholic cirrhosis.

Blood Pressure↗
PubMed1977

Alcoholic hepatitis with and without alcoholic hyaline.

Sixteen cases of alcoholic hepatitis with alcoholic hyaline (Group I) and 13 cases without alcoholic hyaline (Group II) have been collected since 1970. These were most frequently found in the fifth decade in both groups. One female was found in Group I. Cases of about two-thirds of both groups were comsumers of 110 g or more of alcohol per day. No significant differences except fever and erythrocyte sedimentation rate were found in clinical and laboratory changes between both groups. Fatty change in liver biopsy specimens were more frequently seen in Group I than in Group II. The wedged hepatic venous pressure was markedly elevated in alcoholic hepatitis with cirrhosis and moderately elevated in alcoholic hepatitis without cirrhosis. Wedged hepatic venography showed the main portal trunk and extrahepatic collaterals, namely, reversal of the portal flow or such tendency in 2 out of 5 patients of Group I.

Adult↗
PubMedDate not supplied

Chlamydospore formation by Paracoccidioides brasiliensis mycelial form.

To investigate the role of some adverse environmental conditions in chlamydospore formation by the mycelial form of P. brasiliensis, we cultured four P. brasiliensis isolates (18, Bt4, 1183, Pb9) at 25 degrees C within solid agar medium either rich or poor in nutrients. Isolates 18 and 1183 were also cultured under anaerobiosis in a nitrogen atmosphere. Isolate 18 produced great number of terminal and intercalary chlamydospore after 7-10 days of culture in a medium poor in nutrients (2% agar with 0.1% dextrose and polypepton). The three other isolates also produced chlamydospores under the same conditions, but in lower numbers. Chlamydospore production by isolate 18 was abolished when the fungus was cultured in two agar media rich in nutrients (brain heart infusion and potato dextrose agar). Anaerobic incubation of isolate 18 under an atmosphere of N2 showed small mycelial outgrowth with numerous chlamydospores. At the electron microscopical level, the chlamydospores showed one or various nuclei and numerous mitochondria, indicating great potential for further development. Accordingly, chlamydospores produced multiple budding after only 24 h incubation at 35 degrees C. The results demonstrate that under adverse environmental conditions P. brasiliensis mycelial form produces chlamydospores within a short period of time.

Culture Media↗