Distinct effects of recombinant tenascin-C domains on neuronal cell adhesion, growth cone guidance, and neuronal polarity

Using a set of recombinantly expressed proteins, distinct domains of the mouse extracellular matrix glycoprotein tenascin-C, hereafter called tenascin, have been identified to confer adhesion, anti-adhesion, and changes in morphology of neuronal cells. In short-term adhesion assays (1 hr), cerebellar and hippocampal neurons adhered to several domains, encompassing the fibronectin type III-like (FN III) repeats 1-2 and 6-8, as well as to the alternatively spliced FN III repeats and to tenascin itself. Although no short-term adhesion to the EGF repeats containing fragment could be detected under the conditions used, it was anti-adhesive for neuronal cell bodies and repellent for growth cone advance and neuritogenesis. FN III repeats 3-5 were repellent only for growth cones but not for neuronal cell bodies. Neurite outgrowth promoting activities at early stages and induction of a polarized neuronal morphology at later stages of differentiation were associated with the EGF repeats and the FN III repeats 6-8. These observations suggest differential effects of particular domains of the tenascin molecule on distinct cellular compartments, i.e., cell body, axon and dendrite, and existence of multiple neuronal receptors with distinct intracellular signaling features.

Constitutive NOS expression in cultured endothelial cells is elevated by fluid shear stress

The role of chronic fluid shear stress on endothelial constitutive nitric oxide synthase (cNOS) levels may have an important role in vessel diameter control. We subjected primary human umbilical vein endothelial cells (HUVEC) or bovine aortic endothelial cells (BAEC, passages 2-14) to steady laminar shear stress. In both cell types, the intracellular level of cNOS was elevated within 3 h of flow exposure at 25 dyn/cm2 and remained elevated at 6 and 12 h of flow exposure, compared with stationary controls, as indicated by digital immunofluorescence microscopy. Shear stress exposure for 6 h caused a 2.2 +/- 0.3- and 2.8 +/- 0.3-fold elevation of cNOS protein levels in BAEC (n = 3, P < 0.01) and HUVEC (n = 3, P < 0.01), respectively, in the presence or absence of 1 microM dexamethasone. Dexamethasone suppresses induction of the inducible NOS gene, indicating that cNOS was elevated by fluid shear stress. Flow exposure at 4 dyn/cm2 caused no enhancement of cNOS levels in either cell type. The flow induction of the cNOS protein levels was not blocked by preincubation of BAEC with 100-400 microM of NG-nitro-L-arginine methyl ester, indicating that flow-induced NO (or guanosine 3',5'-cyclic monophosphate) was not involved in the elevation of cNOS levels. Protein kinase C inhibitor H-7 (10 microM) had no effect on induction of NOS protein in BAEC exposed to 25 dyn/cm2. The cNOS mRNA levels were found to be elevated by two- to threefold in BAEC after 6 or 12 h of flow exposure at either 4 or 25 dyn/cm2, and this induction of NOS mRNA occurred in the presence of dexamethasone. The elevation of cNOS levels by chronic flow exposure may provide a mechanism for chronic regulation of vessel diameter by endothelial response to prevailing blood flow.

[Rearrangements and fusion gene of AML1 and MTG8 in acute myeloid leukemia M2b]

The t(8;21) reciprocal chromosomal translocation is frequently associated with M2b type of acute myeloid leukemia (AML). Recently, two genes, MTG8 on chromosome 8 and AML1 on chromosome 21, were found. The t(8;21) translocation resulted in rearrangements of the two genes and formation of AML1/MTG8 fusion gene. To clarify the molecular characteristics of AML-M2b, we studied 41 patients with AML-M2b. By Southern blot and hybridization, the rearrangements of AML1 and MTG8 genes were detected in 24 of 30 and 22 of 28 patients, respectively. By means of reverse transcription and polymerase chain reaction (RT-PCR), the AML1/MTG8 chimeric transcript was found in all 37 patients. In 4 patients with AML-M2b of normal karyotype, AML1/MTG8 fusion mRNA and/or rearrangements of AML1 and MTG8 genes were detected. However, among 31 patients with other types of AML, these abnormalities were found in only one patient with AML-M6. These results suggest that rearrangements of AML1, MTG8 genes and/or AML1/MTG8 fusion gene could be regarded as gene marker of AML-M2b that can be applied in the diagnosis and monitoring of therapy and minimal residual disease.

[Clinical value of renal radionuclide imaging for diagnosis of urinary tract tumor]

Combined use of 99mTc-diethylenetriaminepentaacetic acid (DTPA) radionuclide angiography, and 99mTc-gluconate renal venography plus single photo computed tomography (SPECT) were employed for clinical diagnosis of urinary tract tumor. This is what we call serial renal radionuclide imaging (SRI). From Aug, 1989 to May, 1993, 63 patients with urinary tract tumor accepted this examination, including 52 cases with renal space-occupying lesion, 5 cases with retroperitoneal mass outside of kidney, 4 cases with bladder cancer (all 61 cases were confirmed by surgery and pathology) and 2 cases suspected of anastomotic leakage after total cystectomy and Bricker's operation. The results show that 1. The renal space-occupying lesion could be accurately localized by SRI and benign lesions could be differentiated from malignancy. 2. SRI could asertain if a retroperitoneal mass was in or outside of the kidney. 3. Urinary fistula could be demonstrated by SRI, while IVU detection failed.

[Osteoarthritis: clinical and epidemiological investigation]

A population study of 1,722 adults in Chenghai city, Guangdong province showed that the prevalence of osteoarthritis (OA) was 8.3% and there was no significant difference between male and female. The prevalence of OA increased after the age of 40 and reached a peak at 50-55 years. The prevalence of osteoporosis (OP) in OA patients of this population survey and in patients in our clinic was around 30%. OA accompanying OP was more frequently seen in female than male, especially in postmenopausal women. The results of CT screen of lumbar spine in 66 OA patients showed: 89.4% (59 cases) was associated with the protrusion of intervertebrale disc, occurring frequently at L4 and L5. MR imaging of 20 knee joints in 10 cases of OA patients with knee involvement showed: all of the patients were associated with one or all of the following conditions: chondropathies, degeneration or injury of semilunar plate, bursitis and synovitis. It is suggested that OA is a heterogeneous disorder and must be treated with different ways.

A simplified in vivo dosimetry for total body irradiation prior to bone marrow transplantation

For TBI (total body irradiation) prior to BMT (bone marrow transplantation) and in order to guarantee exact treatment, it is necessary to perfect in vivo dosimetry to detect any deviation of the treatment and to verify the dose distribution. A simplified and convenient transmission type in vivo dosimetry and problems are introduced and discussed.

SCM2, a tryptophan permease in Saccharomyces cerevisiae, is important for cell growth

SCM2, a novel gene encoding a yeast tryptophan permease, was cloned as a high-copy-number suppressor of cse2-1. The cse2-1 mutation causes cold sensitivity, temperature sensitivity and chromosome missegregation. However, only the cold-sensitive phenotype of cse2-1 cells is suppressed by SCM2 at high copy. SCM2 is located on the left arm of yeast chromosome XV, adjacent to SUP3 and encodes a 65 kDa protein that is highly homologous to known amino acid permeases. Four out of five disrupted scm2 alleles (scm2 delta 1-delta 4) cause slow growth, whereas one disrupted allele (scm2 delta 5) is lethal. Cells with both the scm2 delta 1 and trp1-delta 101 mutations exhibit a synthetic cold-sensitive phenotype and grow much more slowly at the permissive temperature than cells with a single scm2 delta 1 or trp1-delta 101 mutation. A region of the predicted SCM2 protein is identical to the partial sequence recently reported for the yeast tryptophan permease TAP2, indicating that SCM2 and TAP2 probably encode the same protein.

Safety and immunogenicity of live attenuated hepatitis A virus vaccine (H2 strain) in humans

A study was made in Neijiang City, Sichuan Province to observe the safety and immunogenicity of a live attenuated hepatitis A virus (HAV) vaccine (H2 strain). 3,031 children, aged 6 to 9 years, were injected subcutaneously with 10(6.0) TCID50, 10(5.5) TCID50, and 10(5.0) TCID50 of HAV vaccine; the seroconversion rate and antibody GMT were 97.52%-90.68%, GMT = 1:5.19 +/- 1.90-1:3.36 +/- 1.94; 84.75%-76.27%, GMT = 1:4.29 +/- 1.96-1:2.0 +/- 2.67; 53.23%-51.61%, GMT = 1:2.57 +/- 1.89-1:1.68 +/- 1.41 respectively after 4 weeks to 12 months of inoculation. Forty-eight children in the control group were anti-HAV negative at 4, 8, and 12 weeks; 21 children in the oral group were not antibody positive 4 and 8 weeks after oral administration of the vaccine. The stool specimens of 3 of the 14 vaccinated children were HAA positive. The results suggest that the live attenuated HAV vaccine (H2 strain) is of good immunogenicity and safety.

CSE1 and CSE2, two new genes required for accurate mitotic chromosome segregation in Saccharomyces cerevisiae

By monitoring the mitotic transmission of a marked chromosome bearing a defective centromere, we have identified conditional alleles of two genes involved in chromosome segregation (cse). Mutations in CSE1 and CSE2 have a greater effect on the segregation of chromosomes carrying mutant centromeres than on the segregation of chromosomes with wild-type centromeres. In addition, the cse mutations cause predominantly nondisjunction rather than loss events but do not cause a detectable increase in mitotic recombination. At the restrictive temperature, cse1 and cse2 mutants accumulate large-budded cells, with a significant fraction exhibiting aberrant binucleate morphologies. We cloned the CSE1 and CSE2 genes by complementation of the cold-sensitive phenotypes. Physical and genetic mapping data indicate that CSE1 is linked to HAP2 on the left arm of chromosome VII and CSE2 is adjacent to PRP2 on chromosome XIV. CSE1 is essential and encodes a novel 109-kDa protein. CSE2 encodes a 17-kDa protein with a putative basic-region leucine zipper motif. Disruption of CSE2 causes chromosome missegregation, conditional lethality, and slow growth at the permissive temperature.

Serum lipids and their correlates in Chinese urban and rural populations of Beijing and Guangzhou. PRC-USA Cardiovascular and Cardiopulmonary Epidemiology Research Group

In 1983 and 1984, surveys were conducted in four Chinese population samples, urban and rural for both Beijing and Guangzhou, as part of PRC-USA collaborative research in cardiovascular and cardiopulmonary epidemiology. Serum total cholesterol (TC), HDL-cholesterol (HDL-C), and triglycerides (TG) were measured in 4280 men and 4695 women aged 35-54 years, in laboratories standardized by the US Centers for Disease Control. Age-adjusted mean serum TC was higher in urban than rural samples and generally higher in Beijing than Guangzhou, ranging from 155 mg/dL for Guangzhou rural women to 187 mg/dl for Guangzhou urban women. Group mean values of HDL-C varied from 48 to 59 mg/dl, higher in Beijing than Guangzhou, and higher in women than men. TC/HDL-C ratio ranged from 3.05 to 3.82. Serum TG values were higher for Beijing than Guangzhou; the lowest group mean values of 78 mg/dl and 75 mg/dl were in rural Guangzhou men and women. Mean body mass index (BMI) was uniformly low, ranging from 20 kg/m2 for rural Guangzhou to 24 kg/m2 for urban Beijing. Multiple regression analyses showed that BMI was positively and independently related to serum TC, LDL-C, TG, and TC/HDL-C, and inversely related to HDL-C. Smoking was positively related in both sexes to TG and TC/HDL-C, and inversely related to HDL-C. Smoking was also positively related to TC and LDL-C in men. In men, alcohol was positively related to TC and HDL-C, and was inversely related to TG and TC/HDL-C. Heavy manual work was inversely related to TC, LDL-C, and TC/HDL-C in men, but not related to lipids in women. Thus, for these Chinese population samples, despite their lower serum TC and BMI, the correlates of serum lipids are similar to those in western populations. These variables accounted for only part of the observed urban-rural and north-south differences in serum lipids among these Chinese population samples. The significance of the relatively low serum TC and TG and high HDL-C in relation to low cardiovascular disease in Chinese populations is the object of further investigation in follow-up studies.

[Preparation of antigen and antibody against aflatoxin B1]

Carboxymethyloxime of aflatoxin B1 (AFB1) was synthesized by refluxing AF B1 with carboxymethoxylamine hemihydrochloride for 4 hours in the presence of pyridine. AF B1-BSA (antigen) was made successfully by coupling AF B1-oxime with bovine serum albumin (BSA) in the presence of a water soluble carbodiimide. The rabbits were immunized with the artificial immunogen which had been purified by dialysis. The titers of antisera were determined by indirect enzyme-linked immunosorbent assay (ELISA) which was developed by ourselves. The highest titer was 1:100,000.

[Study on determination of ammonia-nitrogen in water by ammonia gas sensor electrode]

A method for the determination of NH3-N content in water by ammonia gas sensor electrode was studied systematically. Good results were obtained by adding acid to water samples until pH less than 2 for storage and adding EDTA to prevent metal ions from interference. Recoveries varied in the range of 90-104%, and the coefficients of variation less than or equal to 3.4%. The measurement range was 10(-1)-10(-4)micrograms/ml, and the detection limit 0.13 micrograms/ml. The reliability of the method was confirmed by comparison with Nesslerization (P greater than 0.5). This method is simple, rapid, accurate and can directly be applied to the determination of the content of ammonia-nitrogen in colored and turbid water samples.

[Studies of the determination of selenium by hydride generation atomic absorption spectrometry]

Potassium ferricyanide has a masking effect of Cu2+, Ni2+ and other interferential ions in the determination of selenium by hydride generation atomic absorption spectrometry. Interference was not observed in the determination of 5ng/ml of Se(IV) in the presence of 10micrograms/ml of Cu2+ under recommended conditions. The stability of analyte and potassium borohydride solutions in storage was also studied.